GCC(1) GNU GCC(1) NNAAMMEE gcc - GNU project C and C++ compiler SSYYNNOOPPSSIISS gcc [--cc|--SS|--EE] [--ssttdd==_s_t_a_n_d_a_r_d] [--gg] [--ppgg] [--OO_l_e_v_e_l] [--WW_w_a_r_n...] [--WWppeeddaannttiicc] [--II_d_i_r...] [--LL_d_i_r...] [--DD_m_a_c_r_o[=_d_e_f_n]...] [--UU_m_a_c_r_o] [--ff_o_p_t_i_o_n...] [--mm_m_a_c_h_i_n_e_-_o_p_t_i_o_n...] [--oo _o_u_t_f_i_l_e] [@_f_i_l_e] _i_n_f_i_l_e... Only the most useful options are listed here; see below for the remain- der. gg++++ accepts mostly the same options as ggcccc. DDEESSCCRRIIPPTTIIOONN When you invoke GCC, it normally does preprocessing, compilation, as- sembly and linking. The "overall options" allow you to stop this process at an intermediate stage. For example, the --cc option says not to run the linker. Then the output consists of object files output by the assembler. Other options are passed on to one or more stages of processing. Some options control the preprocessor and others the compiler itself. Yet other options control the assembler and linker; most of these are not documented here, since you rarely need to use any of them. Most of the command-line options that you can use with GCC are useful for C programs; when an option is only useful with another language (usually C++), the explanation says so explicitly. If the description for a particular option does not mention a source language, you can use that option with all supported languages. The usual way to run GCC is to run the executable called ggcccc, or _m_a_- _c_h_i_n_e--ggcccc when cross-compiling, or _m_a_c_h_i_n_e--ggcccc--_v_e_r_s_i_o_n to run a spe- cific version of GCC. When you compile C++ programs, you should invoke GCC as gg++++ instead. The ggcccc program accepts options and file names as operands. Many op- tions have multi-letter names; therefore multiple single-letter options may _n_o_t be grouped: --ddvv is very different from --dd --vv. You can mix options and other arguments. For the most part, the order you use doesn't matter. Order does matter when you use several options of the same kind; for example, if you specify --LL more than once, the directories are searched in the order specified. Also, the placement of the --ll option is significant. Many options have long names starting with --ff or with --WW---for example, --ffmmoovvee--lloooopp--iinnvvaarriiaannttss, --WWffoorrmmaatt and so on. Most of these have both positive and negative forms; the negative form of --ffffoooo is --ffnnoo--ffoooo. This manual documents only one of these two forms, whichever one is not the default. Some options take one or more arguments typically separated either by a space or by the equals sign (==) from the option name. Unless docu- mented otherwise, an argument can be either numeric or a string. Nu- meric arguments must typically be small unsigned decimal or hexadecimal integers. Hexadecimal arguments must begin with the 00xx prefix. Argu- ments to options that specify a size threshold of some sort may be ar- bitrarily large decimal or hexadecimal integers followed by a byte size suffix designating a multiple of bytes such as "kB" and "KiB" for kilo- byte and kibibyte, respectively, "MB" and "MiB" for megabyte and mebibyte, "GB" and "GiB" for gigabyte and gigibyte, and so on. Such arguments are designated by _b_y_t_e_-_s_i_z_e in the following text. Refer to the NIST, IEC, and other relevant national and international standards for the full listing and explanation of the binary and decimal byte size prefixes. OOPPTTIIOONNSS OOppttiioonn SSuummmmaarryy Here is a summary of all the options, grouped by type. Explanations are in the following sections. _O_v_e_r_a_l_l _O_p_t_i_o_n_s --cc --SS --EE --oo _f_i_l_e --dduummppbbaassee _d_u_m_p_b_a_s_e --dduummppbbaassee--eexxtt _a_u_x_d_r_o_p_s_u_f --dduummppddiirr _d_u_m_p_p_f_x --xx _l_a_n_g_u_a_g_e --vv --###### ----hheellpp[==_c_l_a_s_s[,,......]] ----ttaarrggeett--hheellpp ----vveerrssiioonn --ppaassss--eexxiitt--ccooddeess --ppiippee --ssppeeccss==_f_i_l_e --wwrraappppeerr @@_f_i_l_e --ffffiillee--pprreeffiixx--mmaapp==_o_l_d==_n_e_w --ffpplluuggiinn==_f_i_l_e --ffpplluu-- ggiinn--aarrgg--_n_a_m_e==_a_r_g --ffdduummpp--aaddaa--ssppeecc[--sslliimm] --ffaaddaa--ssppeecc--ppaarreenntt==_u_n_i_t --ffdduummpp--ggoo--ssppeecc==_f_i_l_e _C _L_a_n_g_u_a_g_e _O_p_t_i_o_n_s --aannssii --ssttdd==_s_t_a_n_d_a_r_d --aauuxx--iinnffoo _f_i_l_e_n_a_m_e --ffaallllooww--ppaarraammeetteerr-- lleessss--vvaarriiaaddiicc--ffuunnccttiioonnss --ffnnoo--aassmm --ffnnoo--bbuuiillttiinn --ffnnoo--bbuuiillttiinn--_f_u_n_c_- _t_i_o_n --ffccoonndd--mmiissmmaattcchh --ffffrreeeessttaannddiinngg --ffggiimmppllee --ffggnnuu--ttmm --ffggnnuu8899--iinnlliinnee --ffhhoosstteedd --ffllaaxx--vveeccttoorr--ccoonnvveerrssiioonnss --ffmmss--eexxtteennssiioonnss --ffooffffllooaadd==_a_r_g --ffooffffllooaadd--ooppttiioonnss==_a_r_g --ffooppeennaacccc --ffooppeennaacccc--ddiimm==_g_e_o_m --ffooppeennmmpp --ffooppeennmmpp--ssiimmdd --ffppeerrmmiitttteedd--fflltt--eevvaall--mmeetthhooddss==_s_t_a_n_d_a_r_d --ffppllaann99--eexxtteennssiioonnss --ffssiiggnneedd--bbiittffiieellddss --ffuunnssiiggnneedd--bbiittffiieellddss --ffssiiggnneedd--cchhaarr --ffuunnssiiggnneedd--cchhaarr --ffssssoo--ssttrruucctt==_e_n_d_i_a_n_n_e_s_s _C_+_+ _L_a_n_g_u_a_g_e _O_p_t_i_o_n_s --ffaabbii--vveerrssiioonn==_n --ffnnoo--aacccceessss--ccoonnttrrooll --ffaalliiggnneedd--nneeww==_n --ffaarrggss--iinn--oorr-- ddeerr==_n --ffcchhaarr88__tt --ffcchheecckk--nneeww --ffccoonnsstteexxpprr--ddeepptthh==_n --ffccoonnsstt-- eexxpprr--ccaacchhee--ddeepptthh==_n --ffccoonnsstteexxpprr--lloooopp--lliimmiitt==_n --ffccoonnsstt-- eexxpprr--ooppss--lliimmiitt==_n --ffnnoo--eelliiddee--ccoonnssttrruuccttoorrss --ffnnoo--eennffoorrccee--eehh--ssppeeccss --ffnnoo--ggnnuu--kkeeyywwoorrddss --ffnnoo--iimmpplliicciitt--tteemmppllaatteess --ffnnoo--iimmpplliicciitt--iinnlliinnee--tteemm-- ppllaatteess --ffnnoo--iimmpplleemmeenntt--iinnlliinneess --ffmmoodduullee--hheeaaddeerr[==_k_i_n_d] --ffmmoodduullee--oonnllyy --ffmmoodduulleess--ttss --ffmmoodduullee--iimmpplliicciitt--iinnlliinnee --ffnnoo--mmoodduullee--llaazzyy --ffmmoodd-- uullee--mmaappppeerr==_s_p_e_c_i_f_i_c_a_t_i_o_n --ffmmoodduullee--vveerrssiioonn--iiggnnoorree --ffmmss--eexxtteennssiioonnss --ffnneeww--iinnhheerriittiinngg--ccttoorrss --ffnneeww--ttttpp--mmaattcchhiinngg --ffnnoo--nnoonnaannssii--bbuuiillttiinnss --ffnnootthhrrooww--oopptt --ffnnoo--ooppeerraattoorr--nnaammeess --ffnnoo--ooppttiioonnaall--ddiiaaggss --ffppeerrmmiiss-- ssiivvee --ffnnoo--pprreettttyy--tteemmppllaatteess --ffnnoo--rrttttii --ffssiizzeedd--ddeeaallllooccaattiioonn --fftteemm-- ppllaattee--bbaacckkttrraaccee--lliimmiitt==_n --fftteemmppllaattee--ddeepptthh==_n --ffnnoo--tthhrreeaaddssaaffee--ssttaattiiccss --ffuussee--ccxxaa--aatteexxiitt --ffnnoo--wweeaakk --nnoossttddiinncc++++ --ffvviissiibbiilliittyy--iinnlliinneess--hhiiddddeenn --ffvviissiibbiilliittyy--mmss--ccoommppaatt --ffeexxtt--nnuummeerriicc--lliitteerraallss --ffllaanngg--iinnffoo--iinn-- cclluuddee--ttrraannssllaattee[==_h_e_a_d_e_r] --ffllaanngg--iinnffoo--iinncclluuddee--ttrraannssllaattee--nnoott --ffllaanngg--iinnffoo--mmoodduullee--ccmmii[==_m_o_d_u_l_e] --ssttddlliibb==_l_i_b_s_t_d_c_+_+_,_l_i_b_c_+_+ --WWaabbii--ttaagg --WWccaattcchh--vvaalluuee --WWccaattcchh--vvaalluuee==_n --WWnnoo--ccllaassss--ccoonnvveerrssiioonn --WWccllaassss--mmeemmaacccceessss --WWccoommmmaa--ssuubbssccrriipptt --WWccoonnddiittiioonnaallllyy--ssuuppppoorrtteedd --WWnnoo--ccoonnvveerrssiioonn--nnuullll --WWccttaadd--mmaayybbee--uunnssuuppppoorrtteedd --WWccttoorr--ddttoorr--pprriivvaaccyy --WWnnoo--ddeelleettee--iinnccoommpplleettee --WWddeelleettee--nnoonn--vviirrttuuaall--ddttoorr --WWnnoo--ddeepprree-- ccaatteedd--aarrrraayy--ccoommppaarree --WWddeepprreeccaatteedd--ccooppyy --WWddeepprreeccaatteedd--ccooppyy--ddttoorr --WWnnoo--ddeepprreeccaatteedd--eennuumm--eennuumm--ccoonnvveerrssiioonn --WWnnoo--ddeepprree-- ccaatteedd--eennuumm--ffllooaatt--ccoonnvveerrssiioonn --WWeeffffcc++++ --WWnnoo--eexxcceeppttiioonnss --WWeexxttrraa--sseemmii --WWnnoo--iinnaacccceessssiibbllee--bbaassee --WWnnoo--iinnhheerriitteedd--vvaarriiaaddiicc--ccttoorr --WWnnoo--iinniitt--lliisstt--lliiffeettiimmee --WWiinnvvaalliidd--iimmppoorrtteedd--mmaaccrrooss --WWnnoo--iinnvvaalliidd--ooffff-- sseettooff --WWnnoo--lliitteerraall--ssuuffffiixx --WWmmiissmmaattcchheedd--nneeww--ddeelleettee --WWmmiiss-- mmaattcchheedd--ttaaggss --WWmmuullttiippllee--iinnhheerriittaannccee --WWnnaammeessppaacceess --WWnnaarrrroowwiinngg --WWnnooeexxcceepptt --WWnnooeexxcceepptt--ttyyppee --WWnnoonn--vviirrttuuaall--ddttoorr --WWppeessssiimmiizziinngg--mmoovvee --WWnnoo--ppllaacceemmeenntt--nneeww --WWppllaacceemmeenntt--nneeww==_n --WWrraannggee--lloooopp--ccoonnssttrruucctt --WWrree-- dduunnddaanntt--mmoovvee --WWrreedduunnddaanntt--ttaaggss --WWrreeoorrddeerr --WWrreeggiisstteerr --WWssttrriicctt--nnuullll--sseennttiinneell --WWnnoo--ssuubboobbjjeecctt--lliinnkkaaggee --WWtteemmppllaatteess --WWnnoo--nnoonn--tteemmppllaattee--ffrriieenndd --WWoolldd--ssttyyllee--ccaasstt --WWoovveerrllooaaddeedd--vviirrttuuaall --WWnnoo--ppmmff--ccoonnvveerrssiioonnss --WWssiiggnn--pprroommoo --WWssiizzeedd--ddeeaallllooccaattiioonn --WWssuugg-- ggeesstt--ffiinnaall--mmeetthhooddss --WWssuuggggeesstt--ffiinnaall--ttyyppeess --WWssuuggggeesstt--oovveerrrriiddee --WWnnoo--tteerrmmiinnaattee --WWuusseelleessss--ccaasstt --WWnnoo--vveexxiinngg--ppaarrssee --WWvviirrttuuaall--iinnhheerrii-- ttaannccee --WWnnoo--vviirrttuuaall--mmoovvee--aassssiiggnn --WWvvoollaattiillee --WWzzeerroo--aass--nnuullll--ppooiinntteerr--ccoonnssttaanntt _O_b_j_e_c_t_i_v_e_-_C _a_n_d _O_b_j_e_c_t_i_v_e_-_C_+_+ _L_a_n_g_u_a_g_e _O_p_t_i_o_n_s --ffccoonnssttaanntt--ssttrriinngg--ccllaassss==_c_l_a_s_s_-_n_a_m_e --ffggnnuu--rruunnttiimmee --ffnneexxtt--rruunnttiimmee --ffnnoo--nniill--rreecceeiivveerrss --ffoobbjjcc--aabbii--vveerrssiioonn==_n --ffoobbjjcc--ccaallll--ccxxxx--ccddttoorrss --ffoobbjjcc--ddiirreecctt--ddiissppaattcchh --ffoobbjjcc--eexxcceeppttiioonnss --ffoobbjjcc--ggcc --ffoobbjjcc--nniillcchheecckk --ffoobbjjcc--ssttdd==oobbjjcc11 --ffnnoo--llooccaall--iivvaarrss --ffiivvaarr--vviissiibbiilliittyy==[ppuubblliicc|pprroo-- tteecctteedd|pprriivvaattee|ppaacckkaaggee] --ffrreeppllaaccee--oobbjjcc--ccllaasssseess --ffzzeerroo--lliinnkk --ggeenn--ddee-- ccllss --WWaassssiiggnn--iinntteerrcceepptt --WWnnoo--pprrooppeerrttyy--aassssiiggnn--ddeeffaauulltt --WWnnoo--pprroottooccooll --WWoobbjjcc--rroooott--ccllaassss --WWsseelleeccttoorr --WWssttrriicctt--sseelleeccttoorr--mmaattcchh --WWuunnddee-- ccllaarreedd--sseelleeccttoorr _D_i_a_g_n_o_s_t_i_c _M_e_s_s_a_g_e _F_o_r_m_a_t_t_i_n_g _O_p_t_i_o_n_s --ffmmeessssaaggee--lleennggtthh==_n --ffddiiaaggnnoossttiiccss--ppllaaiinn--oouuttppuutt --ffddiiaaggnnooss-- ttiiccss--sshhooww--llooccaattiioonn==[oonnccee|eevveerryy--lliinnee] --ffddiiaaggnnooss-- ttiiccss--ccoolloorr==[aauuttoo|nneevveerr|aallwwaayyss] --ffddiiaaggnnoossttiiccss--uurrllss==[aauuttoo|nneevveerr|aall-- wwaayyss] --ffddiiaaggnnoossttiiccss--ffoorrmmaatt==[tteexxtt|jjssoonn] --ffnnoo--ddiiaaggnnoossttiiccss--sshhooww--ooppttiioonn --ffnnoo--ddiiaaggnnoossttiiccss--sshhooww--ccaarreett --ffnnoo--ddiiaaggnnoossttiiccss--sshhooww--llaabbeellss --ffnnoo--ddii-- aaggnnoossttiiccss--sshhooww--lliinnee--nnuummbbeerrss --ffnnoo--ddiiaaggnnoossttiiccss--sshhooww--ccwwee --ffddiiaaggnnooss-- ttiiccss--mmiinniimmuumm--mmaarrggiinn--wwiiddtthh==_w_i_d_t_h --ffddiiaaggnnoossttiiccss--ppaarrsseeaabbllee--ffiixxiittss --ffddiiaaggnnoossttiiccss--ggeenneerraattee--ppaattcchh --ffddiiaaggnnoossttiiccss--sshhooww--tteemmppllaattee--ttrreeee --ffnnoo--eelliiddee--ttyyppee --ffddiiaaggnnoossttiiccss--ppaatthh--ffoorrmmaatt==[nnoonnee|sseeppaarraattee--eevveennttss|iinn-- lliinnee--eevveennttss] --ffddiiaaggnnoossttiiccss--sshhooww--ppaatthh--ddeepptthhss --ffnnoo--sshhooww--ccoolluummnn --ffddii-- aaggnnoossttiiccss--ccoolluummnn--uunniitt==[ddiissppllaayy|bbyyttee] --ffddiiaaggnnoossttiiccss--ccoolluummnn--oorrii-- ggiinn==_o_r_i_g_i_n --ffddiiaaggnnoossttiiccss--eessccaappee--ffoorrmmaatt==[uunniiccooddee|bbyytteess] _W_a_r_n_i_n_g _O_p_t_i_o_n_s --ffssyynnttaaxx--oonnllyy --ffmmaaxx--eerrrroorrss==_n --WWppeeddaannttiicc --ppeeddaannttiicc--eerrrroorrss --ww --WWeexxttrraa --WWaallll --WWaabbii==_n --WWaaddddrreessss --WWnnoo--aaddddrreessss--ooff--ppaacckkeedd--mmeemmbbeerr --WWaaggggrreeggaattee--rreettuurrnn --WWaalllloocc--ssiizzee--llaarrggeerr--tthhaann==_b_y_t_e_-_s_i_z_e --WWaalllloocc--zzeerroo --WWaallllooccaa --WWaallllooccaa--llaarrggeerr--tthhaann==_b_y_t_e_-_s_i_z_e --WWnnoo--aaggggrreessssiivvee--lloooopp--ooppttii-- mmiizzaattiioonnss --WWaarriitthh--ccoonnvveerrssiioonn --WWaarrrraayy--bboouunnddss --WWaarrrraayy--bboouunnddss==_n --WWaarrrraayy--ccoommppaarree --WWnnoo--aattttrriibbuutteess --WWaattttrriibbuuttee--aalliiaass==_n --WWnnoo--aattttrrii-- bbuuttee--aalliiaass --WWnnoo--aattttrriibbuuttee--wwaarrnniinngg --WWbbiiddii--cchhaarrss==[nnoonnee|uunn-- ppaaiirreedd|aannyy|uuccnn] --WWbbooooll--ccoommppaarree --WWbbooooll--ooppeerraattiioonn --WWnnoo--bbuuiillttiinn--ddeecc-- llaarraattiioonn--mmiissmmaattcchh --WWnnoo--bbuuiillttiinn--mmaaccrroo--rreeddeeffiinneedd --WWcc9900--cc9999--ccoommppaatt --WWcc9999--cc1111--ccoommppaatt --WWcc1111--cc22xx--ccoommppaatt --WWcc++++--ccoommppaatt --WWcc++++1111--ccoommppaatt --WWcc++++1144--ccoommppaatt --WWcc++++1177--ccoommppaatt --WWcc++++2200--ccoommppaatt --WWnnoo--cc++++1111--eexxtteennssiioonnss --WWnnoo--cc++++1144--eexxtteennssiioonnss --WWnnoo--cc++++1177--eexxtteennssiioonnss --WWnnoo--cc++++2200--eexxtteennssiioonnss --WWnnoo--cc++++2233--eexxtteennssiioonnss --WWccaasstt--aalliiggnn --WWccaasstt--aalliiggnn==ssttrriicctt --WWccaasstt--ffuunnccttiioonn--ttyyppee --WWccaasstt--qquuaall --WWcchhaarr--ssuubbssccrriippttss --WWcclloobbbbeerreedd --WWccoommmmeenntt --WWccoonnvveerrssiioonn --WWnnoo--ccoovveerraaggee--mmiissmmaattcchh --WWnnoo--ccpppp --WWddaann-- gglliinngg--eellssee --WWddaanngglliinngg--ppooiinntteerr --WWddaanngglliinngg--ppooiinntteerr==_n --WWddaattee--ttiimmee --WWnnoo--ddeepprreeccaatteedd --WWnnoo--ddeepprreeccaatteedd--ddeeccllaarraattiioonnss --WWnnoo--ddeessiiggnnaatteedd--iinniitt --WWddiissaabblleedd--ooppttiimmiizzaattiioonn --WWnnoo--ddiissccaarrddeedd--aarrrraayy--qquuaalliiffiieerrss --WWnnoo--ddiiss-- ccaarrddeedd--qquuaalliiffiieerrss --WWnnoo--ddiivv--bbyy--zzeerroo --WWddoouubbllee--pprroommoottiioonn --WWdduuppllii-- ccaatteedd--bbrraanncchheess --WWdduupplliiccaatteedd--ccoonndd --WWeemmppttyy--bbooddyy --WWnnoo--eennddiiff--llaabbeellss --WWeennuumm--ccoommppaarree --WWeennuumm--ccoonnvveerrssiioonn --WWeerrrroorr --WWeerrrroorr==** --WWeexxppaann-- ssiioonn--ttoo--ddeeffiinneedd --WWffaattaall--eerrrroorrss --WWffllooaatt--ccoonnvveerrssiioonn --WWffllooaatt--eeqquuaall --WWffoorrmmaatt --WWffoorrmmaatt==22 --WWnnoo--ffoorrmmaatt--ccoonnttaaiinnss--nnuull --WWnnoo--ffoorrmmaatt--eexx-- ttrraa--aarrggss --WWffoorrmmaatt--nnoonnlliitteerraall --WWffoorrmmaatt--oovveerrffllooww==_n --WWffoorrmmaatt--sseeccuurriittyy --WWffoorrmmaatt--ssiiggnneeddnneessss --WWffoorrmmaatt--ttrruunnccaattiioonn==_n --WWffoorrmmaatt--yy22kk --WWffrraammee--aaddddrreessss --WWffrraammee--llaarrggeerr--tthhaann==_b_y_t_e_-_s_i_z_e --WWnnoo--ffrreeee--nnoonn-- hheeaapp--oobbjjeecctt --WWnnoo--iiff--nnoott--aalliiggnneedd --WWnnoo--iiggnnoorreedd--aattttrriibbuutteess --WWiigg-- nnoorreedd--qquuaalliiffiieerrss --WWnnoo--iinnccoommppaattiibbllee--ppooiinntteerr--ttyyppeess --WWiimmpplliicciitt --WWiimm-- pplliicciitt--ffaalllltthhrroouugghh --WWiimmpplliicciitt--ffaalllltthhrroouugghh==_n --WWnnoo--iimmpplliicciitt--ffuunncc-- ttiioonn--ddeeccllaarraattiioonn --WWnnoo--iimmpplliicciitt--iinntt --WWiinnffiinniittee--rreeccuurrssiioonn --WWiinniitt--sseellff --WWiinnlliinnee --WWnnoo--iinntt--ccoonnvveerrssiioonn --WWiinntt--iinn--bbooooll--ccoonntteexxtt --WWnnoo--iinntt--ttoo--ppooiinntteerr--ccaasstt --WWnnoo--iinnvvaalliidd--mmeemmoorryy--mmooddeell --WWiinnvvaalliidd--ppcchh --WWjjuummpp--mmiisssseess--iinniitt --WWllaarrggeerr--tthhaann==_b_y_t_e_-_s_i_z_e --WWllooggiiccaall--nnoott--ppaarreenntthhee-- sseess --WWllooggiiccaall--oopp --WWlloonngg--lloonngg --WWnnoo--llttoo--ttyyppee--mmiissmmaattcchh --WWmmaaiinn --WWmmaayybbee--uunniinniittiiaalliizzeedd --WWmmeemmsseett--eelltt--ssiizzee --WWmmeemmsseett--ttrraannssppoosseedd--aarrggss --WWmmiisslleeaaddiinngg--iinnddeennttaattiioonn --WWmmiissssiinngg--aattttrriibbuutteess --WWmmiissssiinngg--bbrraacceess --WWmmiissssiinngg--ffiieelldd--iinniittiiaalliizzeerrss --WWmmiissssiinngg--ffoorrmmaatt--aattttrriibbuuttee --WWmmiissss-- iinngg--iinncclluuddee--ddiirrss --WWmmiissssiinngg--nnoorreettuurrnn --WWnnoo--mmiissssiinngg--pprrooffiillee --WWnnoo--mmuullttiicchhaarr --WWmmuullttiissttaatteemmeenntt--mmaaccrrooss --WWnnoonnnnuullll --WWnnoonnnnuullll--ccoomm-- ppaarree --WWnnoorrmmaalliizzeedd==[nnoonnee|iidd|nnffcc|nnffkkcc] --WWnnuullll--ddeerreeffeerreennccee --WWnnoo--ooddrr --WWooppeennaacccc--ppaarraalllleelliissmm --WWooppeennmmpp--ssiimmdd --WWnnoo--oovveerrffllooww --WWoovveerr-- lleennggtthh--ssttrriinnggss --WWnnoo--oovveerrrriiddee--iinniitt--ssiiddee--eeffffeeccttss --WWppaacckkeedd --WWnnoo--ppaacckkeedd--bbiittffiieelldd--ccoommppaatt --WWppaacckkeedd--nnoott--aalliiggnneedd --WWppaaddddeedd --WWppaarreenntthheesseess --WWnnoo--ppeeddaannttiicc--mmss--ffoorrmmaatt --WWppooiinntteerr--aarriitthh --WWnnoo--ppooiinntteerr--ccoommppaarree --WWnnoo--ppooiinntteerr--ttoo--iinntt--ccaasstt --WWnnoo--pprraaggmmaass --WWnnoo--pprriioo--ccttoorr--ddttoorr --WWrreedduunnddaanntt--ddeeccllss --WWrreessttrriicctt --WWnnoo--rreettuurrnn--lloo-- ccaall--aaddddrr --WWrreettuurrnn--ttyyppee --WWnnoo--ssccaallaarr--ssttoorraaggee--oorrddeerr --WWsseeqquueennccee--ppooiinntt --WWsshhaaddooww --WWsshhaaddooww==gglloobbaall --WWsshhaaddooww==llooccaall --WWsshhaaddooww==ccoommppaattiibbllee--lloo-- ccaall --WWnnoo--sshhaaddooww--iivvaarr --WWnnoo--sshhiifftt--ccoouunntt--nneeggaattiivvee --WWnnoo--sshhiifftt--ccoouunntt--oovveerrffllooww --WWsshhiifftt--nneeggaattiivvee--vvaalluuee --WWnnoo--sshhiifftt--oovveerr-- ffllooww --WWsshhiifftt--oovveerrffllooww==_n --WWssiiggnn--ccoommppaarree --WWssiiggnn--ccoonnvveerrssiioonn --WWnnoo--ssiizzeeooff--aarrrraayy--aarrgguummeenntt --WWssiizzeeooff--aarrrraayy--ddiivv --WWssiizzeeooff--ppooiinntteerr--ddiivv --WWssiizzeeooff--ppooiinntteerr--mmeemmaacccceessss --WWssttaacckk--pprrootteeccttoorr --WWssttaacckk--uussaaggee==_b_y_t_e_- _s_i_z_e --WWssttrriicctt--aalliiaassiinngg --WWssttrriicctt--aalliiaassiinngg==nn --WWssttrriicctt--oovveerrffllooww --WWssttrriicctt--oovveerrffllooww==_n --WWssttrriinngg--ccoommppaarree --WWnnoo--ssttrriinnggoopp--oovveerrffllooww --WWnnoo--ssttrriinnggoopp--oovveerrrreeaadd --WWnnoo--ssttrriinnggoopp--ttrruunnccaattiioonn --WWssuuggggeesstt--aattttrrii-- bbuuttee==[ppuurree|ccoonnsstt|nnoorreettuurrnn|ffoorrmmaatt|mmaalllloocc] --WWsswwiittcchh --WWnnoo--sswwiittcchh--bbooooll --WWsswwiittcchh--ddeeffaauulltt --WWsswwiittcchh--eennuumm --WWnnoo--sswwiittcchh--oouuttssiiddee--rraannggee --WWnnoo--sswwiittcchh--uunnrreeaacchhaabbllee --WWssyynncc--nnaanndd --WWssyysstteemm--hheeaaddeerrss --WWttaauuttoollooggii-- ccaall--ccoommppaarree --WWttrraammppoolliinneess --WWttrriiggrraapphhss --WWttrriivviiaall--aauuttoo--vvaarr--iinniitt --WWttssaann --WWttyyppee--lliimmiittss --WWuunnddeeff --WWuunniinniittiiaalliizzeedd --WWuunnkknnoowwnn--pprraaggmmaass --WWuunnssuuffffiixxeedd--ffllooaatt--ccoonnssttaannttss --WWuunnuusseedd --WWuunnuusseedd--bbuutt--sseett--ppaarraammeetteerr --WWuunnuusseedd--bbuutt--sseett--vvaarriiaabbllee --WWuunnuusseedd--ccoonnsstt--vvaarriiaabbllee --WWuunnuusseedd--ccoonnsstt--vvaarriiaabbllee==_n --WWuunnuusseedd--ffuunnccttiioonn --WWuunnuusseedd--llaabbeell --WWuunnuusseedd--llooccaall--ttyyppeeddeeffss --WWuunnuusseedd--mmaaccrrooss --WWuunnuusseedd--ppaarraammeetteerr --WWnnoo--uunnuusseedd--rreessuulltt --WWuunnuusseedd--vvaalluuee --WWuunnuusseedd--vvaarriiaabbllee --WWnnoo--vvaarraarrggss --WWvvaarriiaaddiicc--mmaaccrrooss --WWvveeccttoorr--ooppeerraattiioonn--ppeerrffoorrmmaannccee --WWvvllaa --WWvvllaa--llaarrggeerr--tthhaann==_b_y_t_e_-_s_i_z_e --WWnnoo--vvllaa--llaarrggeerr--tthhaann --WWvvoollaattiillee--rreeggiiss-- tteerr--vvaarr --WWwwrriittee--ssttrriinnggss --WWzzeerroo--lleennggtthh--bboouunnddss _S_t_a_t_i_c _A_n_a_l_y_z_e_r _O_p_t_i_o_n_s --ffaannaallyyzzeerr --ffaannaallyyzzeerr--ccaallll--ssuummmmaarriieess --ffaannaallyyzzeerr--cchheecckkeerr==_n_a_m_e --ffnnoo--aannaallyyzzeerr--ffeeaassiibbiilliittyy --ffaannaallyyzzeerr--ffiinnee--ggrraaiinneedd --ffnnoo--aannaa-- llyyzzeerr--ssttaattee--mmeerrggee --ffnnoo--aannaallyyzzeerr--ssttaattee--ppuurrggee --ffaannaallyyzzeerr--ttrraannssiittiivviittyy --ffaannaallyyzzeerr--vveerrbboossee--eeddggeess --ffaannaallyyzzeerr--vveerrbboossee--ssttaattee--cchhaannggeess --ffaannaa-- llyyzzeerr--vveerrbboossiittyy==_l_e_v_e_l --ffdduummpp--aannaallyyzzeerr --ffdduummpp--aannaallyyzzeerr--ccaallllggrraapphh --ffdduummpp--aannaallyyzzeerr--eexxppllooddeedd--ggrraapphh --ffdduummpp--aannaallyyzzeerr--eexxppllooddeedd--nnooddeess --ffdduummpp--aannaallyyzzeerr--eexxppllooddeedd--nnooddeess--22 --ffdduummpp--aannaallyyzzeerr--eexxppllooddeedd--nnooddeess--33 --ffdduummpp--aannaallyyzzeerr--eexxppllooddeedd--ppaatthhss --ffdduummpp--aannaallyyzzeerr--ffeeaassiibbiilliittyy --ffdduummpp--aannaallyyzzeerr--jjssoonn --ffdduummpp--aannaallyyzzeerr--ssttaattee--ppuurrggee --ffdduummpp--aannaa-- llyyzzeerr--ssttddeerrrr --ffdduummpp--aannaallyyzzeerr--ssuuppeerrggrraapphh --ffdduummpp--aannaallyyzzeerr--uunnttrraacckkeedd --WWnnoo--aannaallyyzzeerr--ddoouubbllee--ffcclloossee --WWnnoo--aannaallyyzzeerr--ddoouubbllee--ffrreeee --WWnnoo--aannaa-- llyyzzeerr--eexxppoossuurree--tthhrroouugghh--oouuttppuutt--ffiillee --WWnnoo--aannaallyyzzeerr--ffiillee--lleeaakk --WWnnoo--aann-- aallyyzzeerr--ffrreeee--ooff--nnoonn--hheeaapp --WWnnoo--aannaallyyzzeerr--mmaalllloocc--lleeaakk --WWnnoo--aannaa-- llyyzzeerr--mmiissmmaattcchhiinngg--ddeeaallllooccaattiioonn --WWnnoo--aannaallyyzzeerr--nnuullll--aarrgguummeenntt --WWnnoo--aann-- aallyyzzeerr--nnuullll--ddeerreeffeerreennccee --WWnnoo--aannaallyyzzeerr--ppoossssiibbllee--nnuullll--aarrgguummeenntt --WWnnoo--aannaallyyzzeerr--ppoossssiibbllee--nnuullll--ddeerreeffeerreennccee --WWnnoo--aannaa-- llyyzzeerr--sshhiifftt--ccoouunntt--nneeggaattiivvee --WWnnoo--aannaallyyzzeerr--sshhiifftt--ccoouunntt--oovveerrffllooww --WWnnoo--aannaallyyzzeerr--ssttaallee--sseettjjmmpp--bbuuffffeerr --WWnnoo--aannaallyyzzeerr--ttaaiinntteedd--aallllooccaa-- ttiioonn--ssiizzee --WWnnoo--aannaallyyzzeerr--ttaaiinntteedd--aarrrraayy--iinnddeexx --WWnnoo--aannaa-- llyyzzeerr--ttaaiinntteedd--ddiivviissoorr --WWnnoo--aannaallyyzzeerr--ttaaiinntteedd--ooffffsseett --WWnnoo--aannaa-- llyyzzeerr--ttaaiinntteedd--ssiizzee --WWaannaallyyzzeerr--ttoooo--ccoommpplleexx --WWnnoo--aannaallyyzzeerr--uunn-- ssaaffee--ccaallll--wwiitthhiinn--ssiiggnnaall--hhaannddlleerr --WWnnoo--aannaallyyzzeerr--uussee--aafftteerr--ffrreeee --WWnnoo--aannaallyyzzeerr--uussee--ooff--ppooiinntteerr--iinn--ssttaallee--ssttaacckk--ffrraammee --WWnnoo--aannaa-- llyyzzeerr--uussee--ooff--uunniinniittiiaalliizzeedd--vvaalluuee --WWnnoo--aannaallyyzzeerr--wwrriittee--ttoo--ccoonnsstt --WWnnoo--aannaallyyzzeerr--wwrriittee--ttoo--ssttrriinngg--lliitteerraall _C _a_n_d _O_b_j_e_c_t_i_v_e_-_C_-_o_n_l_y _W_a_r_n_i_n_g _O_p_t_i_o_n_s --WWbbaadd--ffuunnccttiioonn--ccaasstt --WWmmiissssiinngg--ddeeccllaarraattiioonnss --WWmmiissssiinngg--ppaarraammee-- tteerr--ttyyppee --WWmmiissssiinngg--pprroottoottyyppeess --WWnneesstteedd--eexxtteerrnnss --WWoolldd--ssttyyllee--ddeeccllaa-- rraattiioonn --WWoolldd--ssttyyllee--ddeeffiinniittiioonn --WWssttrriicctt--pprroottoottyyppeess --WWttrraaddiittiioonnaall --WWttrraaddiittiioonnaall--ccoonnvveerrssiioonn --WWddeeccllaarraattiioonn--aafftteerr--ssttaatteemmeenntt --WWppooiinntteerr--ssiiggnn _D_e_b_u_g_g_i_n_g _O_p_t_i_o_n_s --gg --gg_l_e_v_e_l --ggddwwaarrff --ggddwwaarrff--_v_e_r_s_i_o_n --ggbbttff --ggccttff --ggccttff_l_e_v_e_l --ggggddbb --ggrreeccoorrdd--ggcccc--sswwiittcchheess --ggnnoo--rreeccoorrdd--ggcccc--sswwiittcchheess --ggssttaabbss --ggssttaabbss++ --ggssttrriicctt--ddwwaarrff --ggnnoo--ssttrriicctt--ddwwaarrff --ggaass--lloocc--ssuuppppoorrtt --ggnnoo--aass--lloocc--ssuuppppoorrtt --ggaass--llooccvviieeww--ssuuppppoorrtt --ggnnoo--aass--llooccvviieeww--ssuuppppoorrtt --ggccoolluummnn--iinnffoo --ggnnoo--ccoolluummnn--iinnffoo --ggddwwaarrff3322 --ggddwwaarrff6644 --ggssttaattee-- mmeenntt--ffrroonnttiieerrss --ggnnoo--ssttaatteemmeenntt--ffrroonnttiieerrss --ggvvaarriiaabbllee--llooccaattiioonn--vviieewwss --ggnnoo--vvaarriiaabbllee--llooccaattiioonn--vviieewwss --ggiinntteerrnnaall--rreesseett--llooccaattiioonn--vviieewwss --ggnnoo--iinntteerrnnaall--rreesseett--llooccaattiioonn--vviieewwss --ggiinnlliinnee--ppooiinnttss --ggnnoo--iinn-- lliinnee--ppooiinnttss --ggvvmmss --ggxxccooffff --ggxxccooffff++ --ggzz[==_t_y_p_e] --ggsspplliitt--ddwwaarrff --ggddeessccrriibbee--ddiieess --ggnnoo--ddeessccrriibbee--ddiieess --ffddeebbuugg--pprreeffiixx--mmaapp==_o_l_d==_n_e_w --ffddeebbuugg--ttyyppeess--sseeccttiioonn --ffnnoo--eelliimmiinnaattee--uunnuusseedd--ddeebbuugg--ttyyppeess --ffeemmiitt--ssttrruucctt--ddeebbuugg--bbaasseeoonnllyy --ffeemmiitt--ssttrruucctt--ddeebbuugg--rreedduucceedd --ffeemmiitt--ssttrruucctt--ddeebbuugg--ddeettaaiilleedd[==_s_p_e_c_-_l_i_s_t] --ffnnoo--eelliimmiinnaattee--uunnuusseedd--ddee-- bbuugg--ssyymmbboollss --ffeemmiitt--ccllaassss--ddeebbuugg--aallwwaayyss --ffnnoo--mmeerrggee--ddeebbuugg--ssttrriinnggss --ffnnoo--ddwwaarrff22--ccffii--aassmm --ffvvaarr--ttrraacckkiinngg --ffvvaarr--ttrraacckkiinngg--aassssiiggnnmmeennttss _O_p_t_i_m_i_z_a_t_i_o_n _O_p_t_i_o_n_s --ffaaggggrreessssiivvee--lloooopp--ooppttiimmiizzaattiioonnss --ffaalliiggnn--ffuunnccttiioonnss[[==_n[[::_m::[[_n_2[[::_m_2]]]]]]]] --ffaalliiggnn--jjuummppss[[==_n[[::_m::[[_n_2[[::_m_2]]]]]]]] --ffaalliiggnn--llaabbeellss[[==_n[[::_m::[[_n_2[[::_m_2]]]]]]]] 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--ffiippaa--bbiitt--ccpp --ffiippaa--vvrrpp --ffiippaa--ppttaa --ffiippaa--pprrooffiillee --ffiippaa--ppuurree--ccoonnsstt --ffiippaa--rreeffeerreennccee --ffiippaa--rreeffeerreennccee--aaddddrreessssaabbllee --ffiippaa--ssttaacckk--aalliiggnnmmeenntt --ffiippaa--iiccff --ffiirraa--aallggoorriitthhmm==_a_l_g_o_r_i_t_h_m --fflliivvee--ppaattcchhiinngg==_l_e_v_e_l --ffiirraa--rreeggiioonn==_r_e_g_i_o_n --ffiirraa--hhooiisstt--pprreessssuurree --ffiirraa--lloooopp--pprreessssuurree --ffnnoo--iirraa--sshhaarree--ssaavvee--sslloottss --ffnnoo--iirraa--sshhaarree--ssppiillll--sslloottss --ffiissoollaattee--eerr-- rroonneeoouuss--ppaatthhss--ddeerreeffeerreennccee --ffiissoollaattee--eerrrroonneeoouuss--ppaatthhss--aattttrriibbuuttee --ffiivvooppttss --ffkkeeeepp--iinnlliinnee--ffuunnccttiioonnss --ffkkeeeepp--ssttaattiicc--ffuunnccttiioonnss --ffkkeeeepp--ssttaattiicc--ccoonnssttss --fflliimmiitt--ffuunnccttiioonn--aalliiggnnmmeenntt --fflliivvee--rraannggee--sshhrriinnkkaaggee 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--ffhhaarrddeenn--ccoonnddiittiioonnaall--bbrraanncchheess --ffssttaacckk--pprrootteeccttoorr --ffssttaacckk--pprrootteecc-- ttoorr--aallll --ffssttaacckk--pprrootteeccttoorr--ssttrroonngg --ffssttaacckk--pprrootteeccttoorr--eexxpplliicciitt --ffss-- ttaacckk--cchheecckk --ffssttaacckk--lliimmiitt--rreeggiisstteerr==_r_e_g --ffssttaacckk--lliimmiitt--ssyymmbbooll==_s_y_m --ffnnoo--ssttaacckk--lliimmiitt --ffsspplliitt--ssttaacckk --ffvvttaabbllee--vveerriiffyy==[ssttdd|pprreeiinniitt|nnoonnee] --ffvvttvv--ccoouunnttss --ffvvttvv--ddeebbuugg --ffiinnssttrruummeenntt--ffuunnccttiioonnss --ffiinnssttrruummeenntt--ffuunncc-- ttiioonnss--eexxcclluuddee--ffuunnccttiioonn--lliisstt==_s_y_m,,_s_y_m,,...... --ffiinnssttrruummeenntt--ffuunnccttiioonnss--eexx-- cclluuddee--ffiillee--lliisstt==_f_i_l_e,,_f_i_l_e,,...... -fprofile-prefix-map=_o_l_d=_n_e_w _P_r_e_p_r_o_c_e_s_s_o_r _O_p_t_i_o_n_s --AA_q_u_e_s_t_i_o_n==_a_n_s_w_e_r --AA--_q_u_e_s_t_i_o_n[==_a_n_s_w_e_r] --CC --CCCC --DD_m_a_c_r_o[==_d_e_f_n] --ddDD --ddII --ddMM --ddNN --ddUU --ffddeebbuugg--ccpppp --ffddiirreeccttiivveess--oonnllyy --ffddooll-- llaarrss--iinn--iiddeennttiiffiieerrss --ffeexxeecc--cchhaarrsseett==_c_h_a_r_s_e_t --ffeexxtteennddeedd--iiddeennttiiffiieerrss --ffiinnppuutt--cchhaarrsseett==_c_h_a_r_s_e_t --ffllaarrggee--ssoouurrccee--ffiilleess --ffmmaaccrroo--pprree-- ffiixx--mmaapp==_o_l_d==_n_e_w --ffmmaaxx--iinncclluuddee--ddeepptthh==_d_e_p_t_h --ffnnoo--ccaannoonniiccaall--ssyyss-- tteemm--hheeaaddeerrss --ffppcchh--ddeeppss --ffppcchh--pprreepprroocceessss --ffpprreepprroocceesssseedd --ffttaabb-- ssttoopp==_w_i_d_t_h --ffttrraacckk--mmaaccrroo--eexxppaannssiioonn --ffwwiiddee--eexxeecc--cchhaarrsseett==_c_h_a_r_s_e_t --ffwwoorrkkiinngg--ddiirreeccttoorryy --HH --iimmaaccrrooss _f_i_l_e --iinncclluuddee _f_i_l_e --MM --MMDD --MMFF --MMGG --MMMM --MMMMDD --MMPP --MMQQ --MMTT --MMnnoo--mmoodduulleess --nnoo--iinntteeggrraatteedd--ccpppp --PP --pptthhrreeaadd --rreemmaapp --ttrraaddiittiioonnaall --ttrraaddiittiioonnaall--ccpppp --ttrriiggrraapphhss --UU_m_a_c_r_o --uunnddeeff --WWpp,,_o_p_t_i_o_n --XXpprreepprroocceessssoorr _o_p_t_i_o_n _A_s_s_e_m_b_l_e_r _O_p_t_i_o_n_s --WWaa,,_o_p_t_i_o_n --XXaasssseemmbblleerr _o_p_t_i_o_n _L_i_n_k_e_r _O_p_t_i_o_n_s _o_b_j_e_c_t_-_f_i_l_e_-_n_a_m_e --ffuussee--lldd==_l_i_n_k_e_r --ll_l_i_b_r_a_r_y --nnoossttaarrttffiilleess --nnooddee-- ffaauullttlliibbss --nnoolliibbcc --nnoossttddlliibb --ee _e_n_t_r_y ----eennttrryy==_e_n_t_r_y --ppiiee --pptthhrreeaadd --rr --rrddyynnaammiicc --ss --ssttaattiicc --ssttaattiicc--ppiiee --ssttaattiicc--lliibbggcccc --ssttaattiicc--lliibbssttddcc++++ --ssttaattiicc--lliibbaassaann --ssttaattiicc--lliibbttssaann --ssttaattiicc--lliibbllssaann --ssttaattiicc--lliibbuubbssaann --sshhaarreedd --sshhaarreedd--lliibbggcccc --ssyymmbboolliicc --TT _s_c_r_i_p_t --WWll,,_o_p_t_i_o_n --XXlliinnkkeerr _o_p_t_i_o_n --uu _s_y_m_b_o_l --zz _k_e_y_w_o_r_d _D_i_r_e_c_t_o_r_y _O_p_t_i_o_n_s --BB_p_r_e_f_i_x --II_d_i_r --II-- --iiddiirraafftteerr _d_i_r --iimmaaccrrooss _f_i_l_e --iimmuullttiilliibb _d_i_r --iipplluuggiinnddiirr==_d_i_r --iipprreeffiixx _f_i_l_e --iiqquuoottee _d_i_r --iissyyssrroooott _d_i_r --iissyysstteemm _d_i_r --iiwwiitthhpprreeffiixx _d_i_r --iiwwiitthhpprreeffiixxbbeeffoorree _d_i_r --LL_d_i_r --nnoo--ccaannoonnii-- ccaall--pprreeffiixxeess ----nnoo--ssyyssrroooott--ssuuffffiixx --nnoossttddiinncc --nnoossttddiinncc++++ ----ssyyss-- rroooott==_d_i_r _C_o_d_e _G_e_n_e_r_a_t_i_o_n _O_p_t_i_o_n_s --ffccaallll--ssaavveedd--_r_e_g --ffccaallll--uusseedd--_r_e_g --ffffiixxeedd--_r_e_g --ffeexxcceeppttiioonnss --ffnnoonn--ccaallll--eexxcceeppttiioonnss --ffddeelleettee--ddeeaadd--eexxcceeppttiioonnss --ffuunnwwiinndd--ttaabblleess --ffaassyynncchhrroonnoouuss--uunnwwiinndd--ttaabblleess --ffnnoo--ggnnuu--uunniiqquuee --ffiinnhhiibbiitt--ssiizzee--ddiirreecc-- ttiivvee --ffccoommmmoonn --ffnnoo--iiddeenntt --ffppcccc--ssttrruucctt--rreettuurrnn --ffppiicc --ffPPIICC --ffppiiee --ffPPIIEE --ffnnoo--pplltt --ffnnoo--jjuummpp--ttaabblleess --ffnnoo--bbiitt--tteessttss --ffrreeccoorrdd--ggcccc--sswwiittcchheess --ffrreegg--ssttrruucctt--rreettuurrnn --ffsshhoorrtt--eennuummss --ffsshhoorrtt--wwcchhaarr --ffvveerrbboossee--aassmm --ffppaacckk--ssttrruucctt[[==_n]] --fflleeaaddiinngg--uunnddeerrssccoorree --ffttllss--mmooddeell==_m_o_d_e_l --ffssttaacckk--rreeuussee==_r_e_u_s_e___l_e_v_e_l --ffttrraammppoolliinneess --ffttrraappvv --ffwwrraappvv --ffvviissiibbiilliittyy==[ddeeffaauulltt|iinntteerrnnaall|hhiiddddeenn|pprrootteecctteedd] --ffssttrriicctt--vvoollaattiillee--bbiittffiieellddss --ffssyynncc--lliibbccaallllss _D_e_v_e_l_o_p_e_r _O_p_t_i_o_n_s --dd_l_e_t_t_e_r_s --dduummppssppeeccss --dduummppmmaacchhiinnee --dduummppvveerrssiioonn --dduummppffuullllvveerrssiioonn --ffccaallllggrraapphh--iinnffoo[==ssuu,,ddaa] --ffcchheecckkiinngg --ffcchheecckkiinngg==_n --ffddbbgg--ccnntt--lliisstt --ffddbbgg--ccnntt==_c_o_u_n_t_e_r_-_v_a_l_u_e_-_l_i_s_t --ffddiissaabbllee--iippaa--_p_a_s_s___n_a_m_e --ffddiiss-- aabbllee--rrttll--_p_a_s_s___n_a_m_e --ffddiissaabbllee--rrttll--_p_a_s_s_-_n_a_m_e==_r_a_n_g_e_-_l_i_s_t --ffddiiss-- aabbllee--ttrreeee--_p_a_s_s___n_a_m_e --ffddiissaabbllee--ttrreeee--_p_a_s_s_-_n_a_m_e==_r_a_n_g_e_-_l_i_s_t --ffdduummpp--ddee-- bbuugg --ffdduummpp--eeaarrllyyddeebbuugg --ffdduummpp--nnooaaddddrr --ffdduummpp--uunnnnuummbbeerreedd --ffdduummpp--uunn-- nnuummbbeerreedd--lliinnkkss --ffdduummpp--ffiinnaall--iinnssnnss[==_f_i_l_e] --ffdduummpp--iippaa--aallll --ffdduummpp--iippaa--ccggrraapphh --ffdduummpp--iippaa--iinnlliinnee --ffdduummpp--llaanngg--aallll --ffdduummpp--llaanngg--_s_w_i_t_c_h --ffdduummpp--llaanngg--_s_w_i_t_c_h--_o_p_t_i_o_n_s --ffdduummpp--llaanngg--_s_w_i_t_c_h--_o_p_t_i_o_n_s==_f_i_l_e_n_a_m_e --ffdduummpp--ppaasssseess --ffdduummpp--rrttll--_p_a_s_s --ffdduummpp--rrttll--_p_a_s_s==_f_i_l_e_n_a_m_e --ffdduummpp--ssttaattiissttiiccss --ffdduummpp--ttrreeee--aallll --ffdduummpp--ttrreeee--_s_w_i_t_c_h --ffdduummpp--ttrreeee--_s_w_i_t_c_h--_o_p_t_i_o_n_s --ffdduummpp--ttrreeee--_s_w_i_t_c_h--_o_p_t_i_o_n_s==_f_i_l_e_n_a_m_e --ffccoommppaarree--ddeebbuugg[==_o_p_t_s] --ffccoomm-- ppaarree--ddeebbuugg--sseeccoonndd --ffeennaabbllee--_k_i_n_d--_p_a_s_s --ffeennaabbllee--_k_i_n_d--_p_a_s_s==_r_a_n_g_e_-_l_i_s_t --ffiirraa--vveerrbboossee==_n --ffllttoo--rreeppoorrtt --ffllttoo--rreeppoorrtt--wwppaa --ffmmeemm--rreeppoorrtt--wwppaa --ffmmeemm--rreeppoorrtt --ffpprree--iippaa--mmeemm--rreeppoorrtt --ffppoosstt--iippaa--mmeemm--rreeppoorrtt --ffoopptt--iinnffoo --ffoopptt--iinnffoo--_o_p_t_i_o_n_s[==_f_i_l_e] --ffpprrooffiillee--rreeppoorrtt --ffrraann-- ddoomm--sseeeedd==_s_t_r_i_n_g --ffsscchheedd--vveerrbboossee==_n --ffsseell--sscchheedd--vveerrbboossee --ffsseell--sscchheedd--dduummpp--ccffgg --ffsseell--sscchheedd--ppiippeelliinniinngg--vveerrbboossee --ffssttaattss --ffss-- ttaacckk--uussaaggee --ffttiimmee--rreeppoorrtt --ffttiimmee--rreeppoorrtt--ddeettaaiillss --ffvvaarr--ttrraacckkiinngg--aass-- ssiiggnnmmeennttss--ttooggggllee --ggttooggggllee --pprriinntt--ffiillee--nnaammee==_l_i_b_r_a_r_y --pprriinntt--lliibbggcccc--ffiillee--nnaammee --pprriinntt--mmuullttii--ddiirreeccttoorryy --pprriinntt--mmuullttii--lliibb --pprriinntt--mmuullttii--ooss--ddiirreeccttoorryy --pprriinntt--pprroogg--nnaammee==_p_r_o_g_r_a_m --pprriinntt--sseeaarrcchh--ddiirrss --QQ --pprriinntt--ssyyssrroooott --pprriinntt--ssyyssrroooott--hheeaaddeerrss--ssuuff-- ffiixx --ssaavvee--tteemmppss --ssaavvee--tteemmppss==ccwwdd --ssaavvee--tteemmppss==oobbjj --ttiimmee[==_f_i_l_e] _M_a_c_h_i_n_e_-_D_e_p_e_n_d_e_n_t _O_p_t_i_o_n_s _A_A_r_c_h_6_4 _O_p_t_i_o_n_s --mmaabbii==_n_a_m_e --mmbbiigg--eennddiiaann --mmlliittttllee--eennddiiaann --mmggeenn-- eerraall--rreeggss--oonnllyy --mmccmmooddeell==ttiinnyy --mmccmmooddeell==ssmmaallll --mmccmmooddeell==llaarrggee --mmssttrriicctt--aalliiggnn --mmnnoo--ssttrriicctt--aalliiggnn --mmoommiitt--lleeaaff--ffrraammee--ppooiinntteerr --mmttllss--ddiiaalleecctt==ddeesscc --mmttllss--ddiiaalleecctt==ttrraaddiittiioonnaall --mmttllss--ssiizzee==_s_i_z_e --mmffiixx--ccoorrtteexx--aa5533--883355776699 --mmffiixx--ccoorrtteexx--aa5533--884433441199 --mmllooww--pprreeccii-- ssiioonn--rreecciipp--ssqqrrtt --mmllooww--pprreecciissiioonn--ssqqrrtt --mmllooww--pprreecciissiioonn--ddiivv --mmppcc--rreellaattiivvee--lliitteerraall--llooaaddss --mmssiiggnn--rreettuurrnn--aaddddrreessss==_s_c_o_p_e --mmbbrraanncchh--pprrootteeccttiioonn==_n_o_n_e||_s_t_a_n_d_a_r_d||_p_a_c_-_r_e_t[[++_l_e_a_f ++_b_-_k_e_y]]||_b_t_i --mmhhaarrddeenn--ssllss==_o_p_t_s --mmaarrcchh==_n_a_m_e --mmccppuu==_n_a_m_e --mmttuunnee==_n_a_m_e --mmoovveerr-- rriiddee==_s_t_r_i_n_g --mmvveerrbboossee--ccoosstt--dduummpp --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd==_g_u_a_r_d --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--rreegg==_s_y_s_r_e_g --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ooffff-- sseett==_o_f_f_s_e_t --mmttrraacckk--ssppeeccuullaattiioonn --mmoouuttlliinnee--aattoommiiccss _A_d_a_p_t_e_v_a _E_p_i_p_h_a_n_y _O_p_t_i_o_n_s --mmhhaallff--rreegg--ffiillee --mmpprreeffeerr--sshhoorrtt--iinnssnn--rreeggss --mmbbrraanncchh--ccoosstt==_n_u_m --mmccmmoovvee --mmnnooppss==_n_u_m --mmssoofftt--ccmmppssff --mmsspplliitt--lloohhii --mmppoosstt--iinncc --mmppoosstt--mmooddiiffyy --mmssttaacckk--ooffffsseett==_n_u_m --mmrroouunndd--nneeaarreesstt --mmlloonngg--ccaallllss --mmsshhoorrtt--ccaallllss --mmssmmaallll1166 --mmffpp--mmooddee==_m_o_d_e --mmvveecctt--ddoouu-- bbllee --mmaaxx--vveecctt--aalliiggnn==_n_u_m --mmsspplliitt--vveeccmmoovvee--eeaarrllyy --mm11rreegg--_r_e_g _A_M_D _G_C_N _O_p_t_i_o_n_s --mmaarrcchh==_g_p_u --mmttuunnee==_g_p_u --mmssttaacckk--ssiizzee==_b_y_t_e_s _A_R_C _O_p_t_i_o_n_s --mmbbaarrrreell--sshhiifftteerr --mmjjllii--aallwwaayyss --mmccppuu==_c_p_u --mmAA66 --mmAARRCC660000 --mmAA77 --mmAARRCC770000 --mmddppffpp --mmddppffpp--ccoommppaacctt --mmddppffpp--ffaasstt --mmnnoo--ddppffpp--llrrssrr --mmeeaa --mmnnoo--mmppyy --mmmmuull3322xx1166 --mmmmuull6644 --mmaattoommiicc --mmnnoorrmm --mmssppffpp --mmssppffpp--ccoommppaacctt --mmssppffpp--ffaasstt --mmssiimmdd --mmssoofftt--ffllooaatt --mmsswwaapp --mmccrrcc --mmddsspp--ppaacckkaa --mmddvvbbff --mmlloocckk --mmmmaacc--dd1166 --mmmmaacc--2244 --mmrrttsscc --mmsswwaappee --mmtteelleepphhoonnyy --mmxxyy --mmiissiizzee --mmaannnnoottaattee--aalliiggnn --mmaarrcclliinnuuxx --mmaarrcclliinnuuxx__pprrooff --mmlloonngg--ccaallllss --mmmmeeddiiuumm--ccaallllss --mmssddaattaa --mmiirrqq--ccttrrll--ssaavveedd --mmrrggff--bbaannkkeedd--rreeggss --mmllppcc--wwiiddtthh==_w_i_d_t_h --GG _n_u_m --mmvvoollaattiillee--ccaacchhee --mmttpp--rreeggnnoo==_r_e_g_n_o --mmaalliiggnn--ccaallll --mmaauuttoo--mmooddiiffyy--rreegg --mmbbbbiitt--ppeeeepphhoollee --mmnnoo--bbrrcccc --mmccaassee--vveeccttoorr--ppccrreell --mmccoommppaacctt--ccaasseessii --mmnnoo--ccoonndd--eexxeecc --mmeeaarrllyy--ccbbrraanncchhssii --mmeexxppaanndd--aaddddddii --mmiinnddeexxeedd--llooaaddss --mmllrraa --mmllrraa--pprriioorriittyy--nnoonnee --mmllrraa--pprriioorriittyy--ccoommppaacctt --mmllrraa--pprriioorr-- iittyy--nnoonnccoommppaacctt --mmmmiilllliiccooddee --mmmmiixxeedd--ccooddee --mmqq--ccllaassss --mmRRccqq --mmRRccww --mmssiizzee--lleevveell==_l_e_v_e_l --mmttuunnee==_c_p_u --mmmmuullttccoosstt==_n_u_m --mmccooddee--ddeennssiittyy--ffrraammee --mmuunnaalliiggnn--pprroobb--tthhrreesshhoolldd==_p_r_o_b_a_b_i_l_i_t_y --mmmmppyy--ooppttiioonn==_m_u_l_t_o --mmddiivv--rreemm --mmccooddee--ddeennssiittyy --mmllll6644 --mmffppuu==_f_p_u --mmrrff1166 --mmbbrraanncchh--iinnddeexx _A_R_M _O_p_t_i_o_n_s --mmaappccss--ffrraammee --mmnnoo--aappccss--ffrraammee --mmaabbii==_n_a_m_e --mmaappccss--ssttaacckk--cchheecckk --mmnnoo--aappccss--ssttaacckk--cchheecckk --mmaappccss--rreeeennttrraanntt --mmnnoo--aappccss--rreeeennttrraanntt --mmggeenneerraall--rreeggss--oonnllyy --mmsscchheedd--pprroolloogg --mmnnoo--sscchheedd--pprroolloogg --mmlliittttllee--eennddiiaann --mmbbiigg--eennddiiaann --mmbbee88 --mmbbee3322 --mmffllooaatt--aabbii==_n_a_m_e --mmffpp1166--ffoorrmmaatt==_n_a_m_e --mmtthhuummbb--iinntteerrwwoorrkk --mmnnoo--tthhuummbb--iinntteerrwwoorrkk --mmccppuu==_n_a_m_e --mmaarrcchh==_n_a_m_e --mmffppuu==_n_a_m_e --mmttuunnee==_n_a_m_e --mmpprriinntt--ttuunnee--iinnffoo --mmssttrruuccttuurree--ssiizzee--bboouunnddaarryy==_n --mmaabboorrtt--oonn--nnoorreettuurrnn --mmlloonngg--ccaallllss --mmnnoo--lloonngg--ccaallllss --mmssiinnggllee--ppiicc--bbaassee --mmnnoo--ssiinnggllee--ppiicc--bbaassee --mmppiicc--rreeggiisstteerr==_r_e_g --mmnnoopp--ffuunn--ddlllliimmppoorrtt --mmppookkee--ffuunnccttiioonn--nnaammee --mmtthhuummbb --mmaarrmm --mmfflliipp--tthhuummbb --mmttppccss--ffrraammee --mmttppccss--lleeaaff--ffrraammee --mmccaalllleerr--ssuuppeerr--iinntteerrwwoorrkkiinngg --mmccaalllleeee--ssuuppeerr--iinn-- tteerrwwoorrkkiinngg --mmttpp==_n_a_m_e --mmttllss--ddiiaalleecctt==_d_i_a_l_e_c_t --mmwwoorrdd--rreellooccaattiioonnss --mmffiixx--ccoorrtteexx--mm33--llddrrdd --mmffiixx--ccoorrtteexx--aa5577--aaeess--11774422009988 --mmffiixx--ccoorr-- tteexx--aa7722--aaeess--11665555443311 --mmuunnaalliiggnneedd--aacccceessss --mmnneeoonn--ffoorr--6644bbiittss --mmssllooww--ffllaasshh--ddaattaa --mmaassmm--ssyynnttaaxx--uunniiffiieedd --mmrreessttrriicctt--iitt --mmvveerr-- bboossee--ccoosstt--dduummpp --mmppuurree--ccooddee --mmccmmssee --mmffiixx--ccmmssee--ccvvee--22002211--3355446655 --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd==_g_u_a_r_d --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ooffffsseett==_o_f_f_s_e_t --mmffddppiicc _A_V_R _O_p_t_i_o_n_s --mmmmccuu==_m_c_u --mmaabbssddaattaa --mmaaccccuummuullaattee--aarrggss --mmbbrraanncchh--ccoosstt==_c_o_s_t --mmccaallll--pprroolloogguueess --mmggaass--iissrr--pprroolloogguueess --mmiinntt88 --mmddoouubbllee==_b_i_t_s --mmlloonngg--ddoouubbllee==_b_i_t_s --mmnn__ffllaasshh==_s_i_z_e --mmnnoo--iinntteerrrruuppttss --mmmmaaiinn--iiss--OOSS__ttaasskk --mmrreellaaxx --mmrrmmww --mmssttrriicctt--XX --mmttiinnyy--ssttaacckk --mmffrraacctt--ccoonnvveerrtt--ttrruunnccaattee --mmsshhoorrtt--ccaallllss --nnooddeevviicceelliibb --nnooddeevviiccee-- ssppeeccss --WWaaddddrr--ssppaaccee--ccoonnvveerrtt --WWmmiissssppeelllleedd--iissrr _B_l_a_c_k_f_i_n _O_p_t_i_o_n_s --mmccppuu==_c_p_u[--_s_i_r_e_v_i_s_i_o_n] --mmssiimm --mmoommiitt--lleeaaff--ffrraammee--ppooiinntteerr --mmnnoo--oommiitt--lleeaaff--ffrraammee--ppooiinntteerr --mmssppeecclldd--aannoommaallyy --mmnnoo--ssppeecclldd--aannoommaallyy --mmccssyynncc--aannoommaallyy --mmnnoo--ccssyynncc--aannoommaallyy --mmllooww--6644kk --mmnnoo--llooww6644kk --mmssttaacckk--cchheecckk--ll11 --mmiidd--sshhaarreedd--lliibbrraarryy --mmnnoo--iidd--sshhaarreedd--lliibbrraarryy --mmsshhaarreedd--lliibbrraarryy--iidd==_n --mmlleeaaff--iidd--sshhaarreedd--lliibbrraarryy --mmnnoo--lleeaaff--iidd--sshhaarreedd--lliibbrraarryy --mmsseepp--ddaattaa --mmnnoo--sseepp--ddaattaa --mmlloonngg--ccaallllss --mmnnoo--lloonngg--ccaallllss --mmffaasstt--ffpp --mmiinn-- lliinnee--pplltt --mmmmuullttiiccoorree --mmccoorreeaa --mmccoorreebb --mmssddrraamm --mmiiccppllbb _C_6_X _O_p_t_i_o_n_s --mmbbiigg--eennddiiaann --mmlliittttllee--eennddiiaann --mmaarrcchh==_c_p_u --mmssiimm --mmss-- ddaattaa==_s_d_a_t_a_-_t_y_p_e _C_R_I_S _O_p_t_i_o_n_s --mmccppuu==_c_p_u --mmaarrcchh==_c_p_u --mmttuunnee==_c_p_u --mmmmaaxx--ssttaacckk--ffrraammee==_n --mmeettrraaxx44 --mmeettrraaxx110000 --mmppddeebbuugg --mmcccc--iinniitt --mmnnoo--ssiiddee--eeffffeeccttss --mmssttaacckk--aalliiggnn --mmddaattaa--aalliiggnn --mmccoonnsstt--aalliiggnn --mm3322--bbiitt --mm1166--bbiitt --mm88--bbiitt --mmnnoo--pprroolloogguuee--eeppiilloogguuee --mmeellff --mmaaoouutt --ssiimm --ssiimm22 --mmmmuull--bbuugg--wwoorrkkaarroouunndd --mmnnoo--mmuull--bbuugg--wwoorrkkaarroouunndd _C_R_1_6 _O_p_t_i_o_n_s --mmmmaacc --mmccrr1166ccpplluuss --mmccrr1166cc --mmssiimm --mmiinntt3322 --mmbbiitt--ooppss --mmddaattaa--mmooddeell==_m_o_d_e_l _C_-_S_K_Y _O_p_t_i_o_n_s --mmaarrcchh==_a_r_c_h --mmccppuu==_c_p_u --mmbbiigg--eennddiiaann --EEBB --mmlliitt-- ttllee--eennddiiaann --EELL --mmhhaarrdd--ffllooaatt --mmssoofftt--ffllooaatt --mmffppuu==_f_p_u --mmddoouu-- bbllee--ffllooaatt --mmffddiivvdduu --mmffllooaatt--aabbii==_n_a_m_e --mmeellrrww --mmiissttaacckk --mmmmpp --mmccpp --mmccaacchhee --mmsseeccuurriittyy --mmttrruusstt --mmddsspp --mmeeddsspp --mmvvddsspp --mmddiivv --mmssmmaarrtt --mmhhiigghh--rreeggiisstteerrss --mmaanncchhoorr --mmppuusshhppoopp --mmmmuullttiippllee--ssttlldd --mmccoonnssttppooooll --mmssttaacckk--ssiizzee --mmccccrrtt --mmbbrraanncchh--ccoosstt==_n --mmccssee--cccc --mmsscchheedd--pprroolloogg --mmssiimm _D_a_r_w_i_n _O_p_t_i_o_n_s --aallll__llooaadd --aalllloowwaabbllee__cclliieenntt --aarrcchh --aarrcchh__eerr-- rroorrss__ffaattaall --aarrcchh__oonnllyy --bbiinndd__aatt__llooaadd --bbuunnddllee --bbuunnddllee__llooaaddeerr --cclliieenntt__nnaammee --ccoommppaattiibbiilliittyy__vveerrssiioonn --ccuurrrreenntt__vveerrssiioonn --ddeeaadd__ssttrriipp --ddeeppeennddeennccyy--ffiillee --ddyylliibb__ffiillee --ddyylliinnkkeerr__iinnssttaallll__nnaammee --ddyynnaammiicc --ddyynnaammiicclliibb --eexxppoorrtteedd__ssyymmbboollss__lliisstt --ffiilleelliisstt --ffllaatt__nnaammeessppaaccee --ffoorrccee__ccppuussuubbttyyppee__AALLLL --ffoorrccee__ffllaatt__nnaammeessppaaccee --hheeaaddeerrppaadd__mmaaxx__iinn-- ssttaallll__nnaammeess --iiffrraammeewwoorrkk --iimmaaggee__bbaassee --iinniitt --iinnssttaallll__nnaammee --kkeeeepp__pprriivvaattee__eexxtteerrnnss --mmuullttii__mmoodduullee --mmuullttiippllyy__ddeeffiinneedd --mmuullttii-- ppllyy__ddeeffiinneedd__uunnuusseedd --nnooaallll__llooaadd --nnoo__ddeeaadd__ssttrriipp__iinniittss__aanndd__tteerrmmss --nnooffiixxpprreebbiinnddiinngg --nnoommuullttiiddeeffss --nnoopprreebbiinndd --nnoosseegglliinnkkeeddiitt --ppaaggeezzeerroo__ssiizzee --pprreebbiinndd --pprreebbiinndd__aallll__ttwwoolleevveell__mmoodduulleess --pprrii-- vvaattee__bbuunnddllee --rreeaadd__oonnllyy__rreellooccss --sseeccttaalliiggnn --sseeccttoobbjjeeccttssyymmbboollss --wwhhyyllooaadd --sseegg11aaddddrr --sseeccttccrreeaattee --sseeccttoobbjjeeccttssyymmbboollss --sseeccttoorrddeerr --sseeggaaddddrr --sseeggss__rreeaadd__oonnllyy__aaddddrr --sseeggss__rreeaadd__wwrriittee__aaddddrr --sseegg__aaddddrr__ttaa-- bbllee --sseegg__aaddddrr__ttaabbllee__ffiilleennaammee --sseegglliinnkkeeddiitt --sseeggpprroott --sseeggss__rreeaadd__oonnllyy__aaddddrr --sseeggss__rreeaadd__wwrriittee__aaddddrr --ssiinnggllee__mmoodduullee --ssttaattiicc --ssuubb__lliibbrraarryy --ssuubb__uummbbrreellllaa --ttwwoolleevveell__nnaammeessppaaccee --uummbbrreellllaa --uunnddee-- ffiinneedd --uunneexxppoorrtteedd__ssyymmbboollss__lliisstt 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--mmffrraammee--lliimmiitt==_b_y_t_e_s --mmxxbbppff --mmccoo--rree --mmnnoo--ccoo--rree --mmjjmmppeexxtt --mmjjmmpp3322 --mmaalluu3322 --mmccppuu==_v_e_r_s_i_o_n _F_R_3_0 _O_p_t_i_o_n_s --mmssmmaallll--mmooddeell --mmnnoo--llssiimm _F_T_3_2 _O_p_t_i_o_n_s --mmssiimm --mmllrraa --mmnnooddiivv --mmfftt3322bb --mmccoommpprreessss --mmnnooppmm _F_R_V _O_p_t_i_o_n_s --mmggpprr--3322 --mmggpprr--6644 --mmffpprr--3322 --mmffpprr--6644 --mmhhaarrdd--ffllooaatt --mmssoofftt--ffllooaatt --mmaalllloocc--cccc --mmffiixxeedd--cccc --mmddwwoorrdd --mmnnoo--ddwwoorrdd --mmddoouubbllee --mmnnoo--ddoouubbllee --mmmmeeddiiaa --mmnnoo--mmeeddiiaa --mmmmuullaadddd --mmnnoo--mmuullaadddd --mmffddppiicc --mmiinnlliinnee--pplltt --mmggpprreell--rroo --mmuullttiilliibb--lliibbrraarryy--ppiicc --mmlliinnkkeedd--ffpp --mmlloonngg--ccaallllss --mmaalliiggnn--llaabbeellss --mmlliibbrraarryy--ppiicc --mmaacccc--44 --mmaacccc--88 --mmppaacckk --mmnnoo--ppaacckk --mmnnoo--eeffllaaggss --mmccoonndd--mmoovvee 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--mmffiixx--rr44000000 --mmnnoo--ffiixx--rr44000000 --mmffiixx--rr44440000 --mmnnoo--ffiixx--rr44440000 --mmffiixx--rr55990000 --mmnnoo--ffiixx--rr55990000 --mmffiixx--rr1100000000 --mmnnoo--ffiixx--rr1100000000 --mmffiixx--rrmm77000000 --mmnnoo--ffiixx--rrmm77000000 --mmffiixx--vvrr44112200 --mmnnoo--ffiixx--vvrr44112200 --mmffiixx--vvrr44113300 --mmnnoo--ffiixx--vvrr44113300 --mmffiixx--ssbb11 --mmnnoo--ffiixx--ssbb11 --mmfflluusshh--ffuunncc==_f_u_n_c --mmnnoo--fflluusshh--ffuunncc --mmbbrraanncchh--ccoosstt==_n_u_m --mmbbrraanncchh--lliikkeellyy --mmnnoo--bbrraanncchh--lliikkeellyy --mmccoomm-- ppaacctt--bbrraanncchheess==_p_o_l_i_c_y --mmffpp--eexxcceeppttiioonnss --mmnnoo--ffpp--eexxcceeppttiioonnss --mmvvrr44113300--aalliiggnn --mmnnoo--vvrr44113300--aalliiggnn --mmssyynnccii --mmnnoo--ssyynnccii --mmllxxcc11--ssxxcc11 --mmnnoo--llxxcc11--ssxxcc11 --mmmmaadddd44 --mmnnoo--mmaadddd44 --mmrreellaaxx--ppiicc--ccaallllss --mmnnoo--rree-- llaaxx--ppiicc--ccaallllss --mmmmccoouunntt--rraa--aaddddrreessss --mmffrraammee--hheeaaddeerr--oopptt --mmnnoo--ffrraammee--hheeaaddeerr--oopptt _M_M_I_X _O_p_t_i_o_n_s --mmlliibbffuunnccss --mmnnoo--lliibbffuunnccss --mmeeppssiilloonn --mmnnoo--eeppssiilloonn --mmaabbii==ggnnuu --mmaabbii==mmmmiixxwwaarree --mmzzeerroo--eexxtteenndd --mmkknnuutthhddiivv --mmttoo-- pplleevveell--ssyymmbboollss --mmeellff --mmbbrraanncchh--pprreeddiicctt --mmnnoo--bbrraanncchh--pprreeddiicctt --mmbbaassee--aaddddrreesssseess --mmnnoo--bbaassee--aaddddrreesssseess --mmssiinnggllee--eexxiitt --mmnnoo--ssiinn-- ggllee--eexxiitt _M_N_1_0_3_0_0 _O_p_t_i_o_n_s --mmmmuulltt--bbuugg --mmnnoo--mmuulltt--bbuugg --mmnnoo--aamm3333 --mmaamm3333 --mmaamm3333--22 --mmaamm3344 --mmttuunnee==_c_p_u_-_t_y_p_e --mmrreettuurrnn--ppooiinntteerr--oonn--dd00 --mmnnoo--ccrrtt00 --mmrreellaaxx --mmlliiww --mmsseettllbb _M_o_x_i_e _O_p_t_i_o_n_s --mmeebb --mmeell --mmmmuull..xx --mmnnoo--ccrrtt00 _M_S_P_4_3_0 _O_p_t_i_o_n_s --mmssiimm --mmaassmm--hheexx --mmmmccuu== --mmccppuu== --mmllaarrggee --mmssmmaallll --mmrreellaaxx --mmwwaarrnn--mmccuu --mmccooddee--rreeggiioonn== --mmddaattaa--rreeggiioonn== --mmssiilliiccoonn--eerrrraattaa== --mmssiilliiccoonn--eerrrraattaa--wwaarrnn== --mmhhwwmmuulltt== --mmiinnrrtt --mmttiinnyy--pprriinnttff --mmmmaaxx--iinn-- lliinnee--sshhiifftt== _N_D_S_3_2 _O_p_t_i_o_n_s --mmbbiigg--eennddiiaann --mmlliittttllee--eennddiiaann --mmrreedduucceedd--rreeggss --mmffuullll--rreeggss --mmccmmoovv --mmnnoo--ccmmoovv --mmeexxtt--ppeerrff --mmnnoo--eexxtt--ppeerrff --mmeexxtt--ppeerrff22 --mmnnoo--eexxtt--ppeerrff22 --mmeexxtt--ssttrriinngg --mmnnoo--eexxtt--ssttrriinngg --mmvv33ppuusshh --mmnnoo--vv33ppuusshh --mm1166bbiitt --mmnnoo--1166bbiitt --mmiissrr--vveeccttoorr--ssiizzee==_n_u_m --mmccaacchhee--bblloocckk--ssiizzee==_n_u_m --mmaarrcchh==_a_r_c_h --mmccmmooddeell==_c_o_d_e_-_m_o_d_e_l --mmccttoorr--ddttoorr --mmrreellaaxx _N_i_o_s _I_I _O_p_t_i_o_n_s --GG _n_u_m --mmggppoopptt==_o_p_t_i_o_n --mmggppoopptt --mmnnoo--ggppoopptt --mmgg-- pprreell--sseecc==_r_e_g_e_x_p --mmrr00rreell--sseecc==_r_e_g_e_x_p --mmeell --mmeebb --mmnnoo--bbyyppaassss--ccaacchhee --mmbbyyppaassss--ccaacchhee --mmnnoo--ccaacchhee--vvoollaattiillee --mmccaacchhee--vvoollaattiillee --mmnnoo--ffaasstt--ssww--ddiivv --mmffaasstt--ssww--ddiivv --mmhhww--mmuull --mmnnoo--hhww--mmuull --mmhhww--mmuullxx --mmnnoo--hhww--mmuullxx --mmnnoo--hhww--ddiivv --mmhhww--ddiivv --mmccuussttoomm--_i_n_s_n==_N --mmnnoo--ccuuss-- ttoomm--_i_n_s_n --mmccuussttoomm--ffppuu--ccffgg==_n_a_m_e --mmhhaall --mmssmmaallllcc --mmssyyss--ccrrtt00==_n_a_m_e --mmssyyss--lliibb==_n_a_m_e --mmaarrcchh==_a_r_c_h --mmbbmmxx --mmnnoo--bbmmxx --mmccddxx --mmnnoo--ccddxx _N_v_i_d_i_a _P_T_X _O_p_t_i_o_n_s --mm6644 --mmmmaaiinnkkeerrnneell --mmooppttiimmiizzee _O_p_e_n_R_I_S_C _O_p_t_i_o_n_s --mmbbooaarrdd==_n_a_m_e --mmnneewwlliibb --mmhhaarrdd--mmuull --mmhhaarrdd--ddiivv --mmssoofftt--mmuull --mmssoofftt--ddiivv --mmssoofftt--ffllooaatt --mmhhaarrdd--ffllooaatt --mmddoouubbllee--ffllooaatt --mmuunnoorrddeerreedd--ffllooaatt --mmccmmoovv --mmrroorr --mmrroorrii --mmsseexxtt --mmssffiimmmm --mmsshhffttiimmmm --mmccmmooddeell==_c_o_d_e_-_m_o_d_e_l _P_D_P_-_1_1 _O_p_t_i_o_n_s --mmffppuu --mmssoofftt--ffllooaatt --mmaacc00 --mmnnoo--aacc00 --mm4400 --mm4455 --mm1100 --mmiinntt3322 --mmnnoo--iinntt1166 --mmiinntt1166 --mmnnoo--iinntt3322 --mmsspplliitt --mmuunniixx--aassmm --mmddeecc--aassmm --mmggnnuu--aassmm --mmllrraa _p_i_c_o_C_h_i_p _O_p_t_i_o_n_s --mmaaee==_a_e___t_y_p_e --mmvvlliiww--llooookkaahheeaadd==_N --mmssyymmbbooll--aass--aadd-- ddrreessss --mmnnoo--iinneeffffiicciieenntt--wwaarrnniinnggss _P_o_w_e_r_P_C _O_p_t_i_o_n_s See RS/6000 and PowerPC Options. _P_R_U _O_p_t_i_o_n_s --mmmmccuu==_m_c_u --mmiinnrrtt --mmnnoo--rreellaaxx --mmlloooopp --mmaabbii==_v_a_r_i_a_n_t _R_I_S_C_-_V _O_p_t_i_o_n_s --mmbbrraanncchh--ccoosstt==_N_-_i_n_s_t_r_u_c_t_i_o_n --mmpplltt --mmnnoo--pplltt --mmaabbii==_A_B_I_-_s_t_r_i_n_g --mmffddiivv --mmnnoo--ffddiivv --mmddiivv --mmnnoo--ddiivv --mmiissaa--ssppeecc==_I_S_A_- _s_p_e_c_-_s_t_r_i_n_g --mmaarrcchh==_I_S_A_-_s_t_r_i_n_g --mmttuunnee==_p_r_o_c_e_s_s_o_r_-_s_t_r_i_n_g --mmpprree-- ffeerrrreedd--ssttaacckk--bboouunnddaarryy==_n_u_m --mmssmmaallll--ddaattaa--lliimmiitt==_N_-_b_y_t_e_s --mmssaavvee--rreessttoorree --mmnnoo--ssaavvee--rreessttoorree --mmsshhoorrtteenn--mmeemmrreeffss --mmnnoo--sshhoorrtteenn--mmeemmrreeffss --mmssttrriicctt--aalliiggnn --mmnnoo--ssttrriicctt--aalliiggnn --mmccmmooddeell==mmeeddllooww --mmccmmooddeell==mmeeddaannyy --mmeexxpplliicciitt--rreellooccss --mmnnoo--eexxpplliicciitt--rreellooccss --mmrreellaaxx --mmnnoo--rreellaaxx --mmrriissccvv--aattttrriibbuuttee --mmmmoo--rriissccvv--aattttrriibbuuttee --mmaalliiggnn--ddaattaa==_t_y_p_e --mmbbiigg--eenn-- ddiiaann --mmlliittttllee--eennddiiaann --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd==_g_u_a_r_d --mmssttaacckk--pprrootteecc-- ttoorr--gguuaarrdd--rreegg==_r_e_g --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ooffffsseett==_o_f_f_s_e_t _R_L_7_8 _O_p_t_i_o_n_s --mmssiimm --mmmmuull==nnoonnee --mmmmuull==gg1133 --mmmmuull==gg1144 --mmaallllrreeggss --mmccppuu==gg1100 --mmccppuu==gg1133 --mmccppuu==gg1144 --mmgg1100 --mmgg1133 --mmgg1144 --mm6644bbiitt--ddoouu-- bblleess --mm3322bbiitt--ddoouubblleess --mmssaavvee--mmdduucc--iinn--iinntteerrrruuppttss _R_S_/_6_0_0_0 _a_n_d _P_o_w_e_r_P_C _O_p_t_i_o_n_s --mmccppuu==_c_p_u_-_t_y_p_e --mmttuunnee==_c_p_u_-_t_y_p_e --mmcc-- mmooddeell==_c_o_d_e_-_m_o_d_e_l --mmppoowweerrppcc6644 --mmaallttiivveecc --mmnnoo--aallttiivveecc --mmppooww-- eerrppcc--ggppoopptt --mmnnoo--ppoowweerrppcc--ggppoopptt --mmppoowweerrppcc--ggffxxoopptt --mmnnoo--ppoowweerrppcc--ggffxx-- oopptt --mmmmffccrrff --mmnnoo--mmffccrrff --mmppooppccnnttbb --mmnnoo--ppooppccnnttbb --mmppooppccnnttdd --mmnnoo--ppooppccnnttdd --mmffpprrnndd --mmnnoo--ffpprrnndd --mmccmmppbb --mmnnoo--ccmmppbb --mmhhaarrdd--ddffpp --mmnnoo--hhaarrdd--ddffpp --mmffuullll--ttoocc --mmmmiinniimmaall--ttoocc --mmnnoo--ffpp--iinn--ttoocc --mmnnoo--ssuumm--iinn--ttoocc --mm6644 --mm3322 --mmxxll--ccoommppaatt --mmnnoo--xxll--ccoommppaatt --mmppee --mmaa-- lliiggnn--ppoowweerr --mmaalliiggnn--nnaattuurraall --mmssoofftt--ffllooaatt --mmhhaarrdd--ffllooaatt --mmmmuullttiippllee --mmnnoo--mmuullttiippllee --mmuuppddaattee --mmnnoo--uuppddaattee --mmaavvooiidd--iinnddeexxeedd--aaddddrreesssseess --mmnnoo--aavvooiidd--iinnddeexxeedd--aaddddrreesssseess --mmffuusseedd--mmaadddd --mmnnoo--ffuusseedd--mmaadddd --mmbbiitt--aalliiggnn --mmnnoo--bbiitt--aalliiggnn --mmssttrriicctt--aalliiggnn --mmnnoo--ssttrriicctt--aalliiggnn --mmrreellooccaattaabbllee --mmnnoo--rreellooccaattaabbllee --mmrreellooccaattaabbllee--lliibb --mmnnoo--rreellooccaatt-- aabbllee--lliibb --mmttoocc --mmnnoo--ttoocc --mmlliittttllee --mmlliittttllee--eennddiiaann --mmbbiigg --mmbbiigg--eennddiiaann --mmddyynnaammiicc--nnoo--ppiicc --mmsswwddiivv --mmssiinnggllee--ppiicc--bbaassee --mmpprriioorrii-- ttiizzee--rreessttrriicctteedd--iinnssnnss==_p_r_i_o_r_i_t_y --mmsscchheedd--ccoossttllyy--ddeepp==_d_e_p_e_n_d_e_n_c_e___t_y_p_e --mmiinnsseerrtt--sscchheedd--nnooppss==_s_c_h_e_m_e --mmccaallll--aaiixxddeesscc --mmccaallll--eeaabbii --mmccaallll--ffrreeeebbssdd --mmccaallll--lliinnuuxx --mmccaallll--nneettbbssdd --mmccaallll--ooppeennbbssdd --mmccaallll--ssyyssvv --mmccaallll--ssyyssvv--eeaabbii --mmccaallll--ssyyssvv--nnooeeaabbii --mmttrraaccee-- bbaacckk==_t_r_a_c_e_b_a_c_k___t_y_p_e --mmaaiixx--ssttrruucctt--rreettuurrnn --mmssvvrr44--ssttrruucctt--rreettuurrnn --mmaabbii==_a_b_i_-_t_y_p_e --mmsseeccuurree--pplltt --mmbbssss--pplltt --mmlloonnggccaallll --mmnnoo--lloonnggccaallll --mmppllttsseeqq --mmnnoo--ppllttsseeqq --mmbblloocckk--mmoovvee--iinnlliinnee--lliimmiitt==_n_u_m --mmbblloocckk--ccoomm-- ppaarree--iinnlliinnee--lliimmiitt==_n_u_m --mmbblloocckk--ccoommppaarree--iinnlliinnee--lloooopp--lliimmiitt==_n_u_m --mmnnoo--bblloocckk--ooppss--uunnaalliiggnneedd--vvssxx --mmssttrriinngg--ccoommppaarree--iinnlliinnee--lliimmiitt==_n_u_m --mmiisseell --mmnnoo--iisseell --mmvvrrssaavvee --mmnnoo--vvrrssaavvee --mmmmuullhhww --mmnnoo--mmuullhhww --mmddllmmzzbb --mmnnoo--ddllmmzzbb --mmpprroottoottyyppee --mmnnoo--pprroottoottyyppee --mmssiimm --mmmmvvmmee --mmaaddss --mmyyeell-- lloowwkknniiffee --mmeemmbb --mmssddaattaa --mmssddaattaa==_o_p_t --mmrreeaaddoonnllyy--iinn--ssddaattaa --mmvvxx-- wwoorrkkss --GG _n_u_m --mmrreecciipp --mmrreecciipp==_o_p_t --mmnnoo--rreecciipp --mmrreecciipp--pprreecciissiioonn --mmnnoo--rreecciipp--pprreecciissiioonn --mmvveecclliibbaabbii==_t_y_p_e --mmffrriizz --mmnnoo--ffrriizz --mmppooiinntt-- eerrss--ttoo--nneesstteedd--ffuunnccttiioonnss --mmnnoo--ppooiinntteerrss--ttoo--nneesstteedd--ffuunnccttiioonnss --mmssaavvee--ttoocc--iinnddiirreecctt --mmnnoo--ssaavvee--ttoocc--iinnddiirreecctt --mmppoowweerr88--ffuussiioonn --mmnnoo--mmppoowweerr88--ffuussiioonn --mmppoowweerr88--vveeccttoorr --mmnnoo--ppoowweerr88--vveeccttoorr --mmccrryyppttoo --mmnnoo--ccrryyppttoo --mmhhttmm --mmnnoo--hhttmm --mmqquuaadd--mmeemmoorryy --mmnnoo--qquuaadd--mmeemmoorryy --mmqquuaadd--mmeemmoorryy--aattoommiicc --mmnnoo--qquuaadd--mmeemmoorryy--aattoommiicc --mmccoommppaatt--aalliiggnn--ppaarrmm --mmnnoo--ccoommppaatt--aalliiggnn--ppaarrmm --mmffllooaatt112288 --mmnnoo--ffllooaatt112288 --mmffllooaatt112288--hhaarrdd-- wwaarree --mmnnoo--ffllooaatt112288--hhaarrddwwaarree --mmggnnuu--aattttrriibbuuttee --mmnnoo--ggnnuu--aattttrriibbuuttee --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd==_g_u_a_r_d --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--rreegg==_r_e_g --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ooffffsseett==_o_f_f_s_e_t --mmpprreeffiixxeedd --mmnnoo--pprreeffiixxeedd --mmppccrreell --mmnnoo--ppccrreell --mmmmmmaa --mmnnoo--mmmmmmaa --mmrroopp--pprrootteecctt --mmnnoo--rroopp--pprrootteecctt --mmpprriivviilleeggeedd --mmnnoo--pprriivviilleeggeedd _R_X _O_p_t_i_o_n_s --mm6644bbiitt--ddoouubblleess --mm3322bbiitt--ddoouubblleess --ffppuu --nnooffppuu --mmccppuu== --mmbbiigg--eennddiiaann--ddaattaa --mmlliittttllee--eennddiiaann--ddaattaa --mmssmmaallll--ddaattaa --mmssiimm --mmnnoo--ssiimm --mmaass110000--ssyynnttaaxx --mmnnoo--aass110000--ssyynnttaaxx --mmrreellaaxx --mmmmaaxx--ccoonn-- ssttaanntt--ssiizzee== --mmiinntt--rreeggiisstteerr== --mmppiidd --mmaallllooww--ssttrriinngg--iinnssnnss --mmnnoo--aall-- llooww--ssttrriinngg--iinnssnnss --mmjjssrr --mmnnoo--wwaarrnn--mmuullttiippllee--ffaasstt--iinntteerrrruuppttss --mmssaavvee--aacccc--iinn--iinntteerrrruuppttss _S_/_3_9_0 _a_n_d _z_S_e_r_i_e_s _O_p_t_i_o_n_s --mmttuunnee==_c_p_u_-_t_y_p_e --mmaarrcchh==_c_p_u_-_t_y_p_e --mmhhaarrdd--ffllooaatt --mmssoofftt--ffllooaatt --mmhhaarrdd--ddffpp --mmnnoo--hhaarrdd--ddffpp --mmlloonngg--ddoouu-- bbllee--6644 --mmlloonngg--ddoouubbllee--112288 --mmbbaacckkcchhaaiinn --mmnnoo--bbaacckkcchhaaiinn --mmppaacckkeedd--ssttaacckk --mmnnoo--ppaacckkeedd--ssttaacckk --mmssmmaallll--eexxeecc --mmnnoo--ssmmaallll--eexxeecc --mmmmvvccllee --mmnnoo--mmvvccllee --mm6644 --mm3311 --mmddeebbuugg --mmnnoo--ddeebbuugg --mmeessaa --mmzzaarrcchh --mmhhttmm --mmvvxx --mmzzvveeccttoorr --mmttppff--ttrraaccee --mmnnoo--ttppff--ttrraaccee --mmttppff--ttrraaccee--sskkiipp --mmnnoo--ttppff--ttrraaccee--sskkiipp --mmffuusseedd--mmaadddd --mmnnoo--ffuusseedd--mmaadddd --mmwwaarrnn--ffrraammeessiizzee --mmwwaarrnn--ddyynnaammiiccssttaacckk --mmssttaacckk--ssiizzee --mmssttaacckk--gguuaarrdd --mmhhoottppaattcchh==_h_a_l_f_w_o_r_d_s,,_h_a_l_f_w_o_r_d_s _S_c_o_r_e _O_p_t_i_o_n_s --mmeebb --mmeell --mmnnhhwwlloooopp --mmuullss --mmmmaacc --mmssccoorree55 --mmssccoorree55uu --mmssccoorree77 --mmssccoorree77dd _S_H _O_p_t_i_o_n_s --mm11 --mm22 --mm22ee --mm22aa--nnooffppuu --mm22aa--ssiinnggllee--oonnllyy --mm22aa--ssiinnggllee --mm22aa --mm33 --mm33ee --mm44--nnooffppuu --mm44--ssiinnggllee--oonnllyy --mm44--ssiinnggllee --mm44 --mm44aa--nnooffppuu --mm44aa--ssiinnggllee--oonnllyy --mm44aa--ssiinnggllee --mm44aa --mm44aall --mmbb --mmll --mmddaalliiggnn --mmrreellaaxx --mmbbiiggttaabbllee --mmffmmoovvdd --mmrreenneessaass --mmnnoo--rreenneessaass --mmnnoommaaccssaavvee --mmiieeeeee --mmnnoo--iieeeeee --mmbbiittooppss --mmiissiizzee --mmiinnlliinnee--iicc__iinn-- vvaalliiddaattee --mmppaaddssttrruucctt --mmpprreeffeerrggoott --mmuusseerrmmooddee --mmuullttccoosstt==_n_u_m_b_e_r --mmddiivv==_s_t_r_a_t_e_g_y --mmddiivvssii33__lliibbffuunncc==_n_a_m_e --mmffiixxeedd--rraannggee==_r_e_g_i_s_t_e_r_-_r_a_n_g_e --mmaaccccuummuullaattee--oouuttggooiinngg--aarrggss --mmaattoommiicc--mmooddeell==_a_t_o_m_i_c_-_m_o_d_e_l --mmbbrraanncchh--ccoosstt==_n_u_m --mmzzddccbbrraanncchh --mmnnoo--zzddccbbrraanncchh --mmccbbrraanncchh--ffoorrccee--ddee-- llaayy--sslloott --mmffuusseedd--mmaadddd --mmnnoo--ffuusseedd--mmaadddd --mmffssccaa --mmnnoo--ffssccaa --mmffssrrrraa --mmnnoo--ffssrrrraa --mmpprreetteenndd--ccmmoovvee --mmttaass _S_o_l_a_r_i_s _2 _O_p_t_i_o_n_s --mmcclleeaarr--hhwwccaapp --mmnnoo--cclleeaarr--hhwwccaapp --mmiimmppuurree--tteexxtt --mmnnoo--iimmppuurree--tteexxtt --pptthhrreeaaddss _S_P_A_R_C _O_p_t_i_o_n_s --mmccppuu==_c_p_u_-_t_y_p_e --mmttuunnee==_c_p_u_-_t_y_p_e --mmccmmooddeell==_c_o_d_e_-_m_o_d_e_l --mmmmeemmoorryy--mmooddeell==_m_e_m_-_m_o_d_e_l --mm3322 --mm6644 --mmaapppp--rreeggss --mmnnoo--aapppp--rreeggss --mmffaasstteerr--ssttrruuccttss --mmnnoo--ffaasstteerr--ssttrruuccttss --mmffllaatt --mmnnoo--ffllaatt --mmffppuu --mmnnoo--ffppuu --mmhhaarrdd--ffllooaatt --mmssoofftt--ffllooaatt --mmhhaarrdd--qquuaadd--ffllooaatt --mmssoofftt--qquuaadd--ffllooaatt --mmssttaacckk--bbiiaass --mmnnoo--ssttaacckk--bbiiaass --mmssttdd--ssttrruucctt--rreettuurrnn --mmnnoo--ssttdd--ssttrruucctt--rreettuurrnn --mmuunnaalliiggnneedd--ddoouubblleess --mmnnoo--uunnaalliiggnneedd--ddoouubblleess --mmuusseerr--mmooddee --mmnnoo--uusseerr--mmooddee --mmvv88pplluuss --mmnnoo--vv88pplluuss --mmvviiss --mmnnoo--vviiss --mmvviiss22 --mmnnoo--vviiss22 --mmvviiss33 --mmnnoo--vviiss33 --mmvviiss44 --mmnnoo--vviiss44 --mmvviiss44bb --mmnnoo--vviiss44bb --mmccbbccoonndd --mmnnoo--ccbbccoonndd --mmffmmaaff --mmnnoo--ffmmaaff --mmffssmmuulldd --mmnnoo--ffssmmuulldd --mmppooppcc --mmnnoo--ppooppcc --mmssuubbxxcc --mmnnoo--ssuubbxxcc --mmffiixx--aatt669977ff --mmffiixx--uutt669999 --mmffiixx--uutt770000 --mmffiixx--ggrr771122rrcc --mmllrraa --mmnnoo--llrraa _S_y_s_t_e_m _V _O_p_t_i_o_n_s --QQyy --QQnn --YYPP,,_p_a_t_h_s --YYmm,,_d_i_r _T_I_L_E_-_G_x _O_p_t_i_o_n_s --mmccppuu==CCPPUU --mm3322 --mm6644 --mmbbiigg--eennddiiaann --mmlliittttllee--eenn-- ddiiaann --mmccmmooddeell==_c_o_d_e_-_m_o_d_e_l _T_I_L_E_P_r_o _O_p_t_i_o_n_s --mmccppuu==_c_p_u --mm3322 _V_8_5_0 _O_p_t_i_o_n_s --mmlloonngg--ccaallllss --mmnnoo--lloonngg--ccaallllss --mmeepp --mmnnoo--eepp --mmpprroo-- lloogg--ffuunnccttiioonn --mmnnoo--pprroolloogg--ffuunnccttiioonn --mmssppaaccee --mmttddaa==_n --mmssddaa==_n --mmzzddaa==_n --mmaapppp--rreeggss --mmnnoo--aapppp--rreeggss --mmddiissaabbllee--ccaalllltt --mmnnoo--ddiiss-- aabbllee--ccaalllltt --mmvv885500ee22vv33 --mmvv885500ee22 --mmvv885500ee11 --mmvv885500eess --mmvv885500ee --mmvv885500 --mmvv885500ee33vv55 --mmlloooopp --mmrreellaaxx --mmlloonngg--jjuummppss --mmssoofftt--ffllooaatt --mmhhaarrdd--ffllooaatt --mmggcccc--aabbii --mmrrhh885500--aabbii --mmbbiigg--sswwiittcchh _V_A_X _O_p_t_i_o_n_s --mmgg --mmggnnuu --mmuunniixx --mmllrraa _V_i_s_i_u_m _O_p_t_i_o_n_s --mmddeebbuugg --mmssiimm --mmffppuu --mmnnoo--ffppuu --mmhhaarrdd--ffllooaatt --mmssoofftt--ffllooaatt --mmccppuu==_c_p_u_-_t_y_p_e --mmttuunnee==_c_p_u_-_t_y_p_e --mmssvv--mmooddee --mmuusseerr--mmooddee _V_M_S _O_p_t_i_o_n_s --mmvvmmss--rreettuurrnn--ccooddeess --mmddeebbuugg--mmaaiinn==_p_r_e_f_i_x --mmmmaalllloocc6644 --mmppooiinntteerr--ssiizzee==_s_i_z_e _V_x_W_o_r_k_s _O_p_t_i_o_n_s --mmrrttpp --nnoonn--ssttaattiicc --BBssttaattiicc --BBddyynnaammiicc --XXbbiinndd--llaazzyy --XXbbiinndd--nnooww _x_8_6 _O_p_t_i_o_n_s --mmttuunnee==_c_p_u_-_t_y_p_e --mmaarrcchh==_c_p_u_-_t_y_p_e --mmttuunnee--ccttrrll==_f_e_a_t_u_r_e_- _l_i_s_t --mmdduummpp--ttuunnee--ffeeaattuurreess --mmnnoo--ddeeffaauulltt --mmffppmmaatthh==_u_n_i_t --mmaassmm==_d_i_- _a_l_e_c_t --mmnnoo--ffaannccyy--mmaatthh--338877 --mmnnoo--ffpp--rreett--iinn--338877 --mm8800338877 --mmhhaarrdd--ffllooaatt --mmssoofftt--ffllooaatt --mmnnoo--wwiiddee--mmuullttiippllyy --mmrrttdd --mmaalliiggnn--ddoouu-- bbllee --mmpprreeffeerrrreedd--ssttaacckk--bboouunnddaarryy==_n_u_m --mmiinnccoommiinngg--ssttaacckk--bboouunnddaarryy==_n_u_m --mmcclldd --mmccxx1166 --mmssaahhff --mmmmoovvbbee --mmccrrcc3322 --mmmmwwaaiitt --mmrreecciipp --mmrree-- cciipp==_o_p_t --mmvvzzeerroouuppppeerr --mmpprreeffeerr--aavvxx112288 --mmpprreeffeerr--vveeccttoorr--wwiiddtthh==_o_p_t --mmmmoovvee--mmaaxx==_b_i_t_s --mmssttoorree--mmaaxx==_b_i_t_s --mmmmmmxx --mmssssee --mmssssee22 --mmssssee33 --mmssssssee33 --mmssssee44..11 --mmssssee44..22 --mmssssee44 --mmaavvxx --mmaavvxx22 --mmaavvxx551122ff --mmaavvxx551122ppff --mmaavvxx551122eerr --mmaavvxx551122ccdd --mmaavvxx551122vvll --mmaavvxx551122bbww --mmaavvxx551122ddqq --mmaavvxx551122iiffmmaa --mmaavvxx551122vvbbmmii --mmsshhaa --mmaaeess --mmppccllmmuull --mmff-- ssggssbbaassee --mmrrddrrnndd --mmff1166cc --mmffmmaa --mmppccoonnffiigg --mmwwbbnnooiinnvvdd --mmppttwwrriittee --mmpprreeffeettcchhwwtt11 --mmccllfflluusshhoopptt --mmccllwwbb --mmxxssaavveecc --mmxxssaavveess --mmssssee44aa --mm33ddnnooww --mm33ddnnoowwaa --mmppooppccnntt --mmaabbmm --mmbbmmii --mmttbbmm --mmffmmaa44 --mmxxoopp --mmaaddxx --mmllzzccnntt --mmbbmmii22 --mmffxxssrr --mmxxssaavvee --mmxxssaavveeoopptt --mmrrttmm --mmhhllee --mmllwwpp --mmmmwwaaiittxx --mmccllzzeerroo --mmppkkuu --mmtthhrreeaaddss --mmggffnnii --mmvvaaeess --mmwwaaiitt-- ppkkgg --mmsshhssttkk --mmmmaannuuaall--eennddbbrr --mmffoorrccee--iinnddiirreecctt--ccaallll --mmaavvxx551122vvbbmmii22 --mmaavvxx551122bbff1166 --mmeennqqccmmdd --mmvvppccllmmuullqqddqq --mmaavvxx551122bbiittaallgg --mmmmoovvddiirrii --mmmmoovvddiirr6644bb --mmaavvxx551122vvppooppccnnttddqq --mmaavvxx55112244ffmmaappss --mmaavvxx551122vvnnnnii --mmaavvxx55112244vvnnnniiww --mmpprrffcchhww --mmrrddppiidd --mmrrddsseeeedd --mmssggxx --mmaavvxx551122vvpp22iinntteerr-- sseecctt --mmsseerriiaalliizzee --mmttssxxllddttrrkk --mmaammxx--ttiillee --mmaammxx--iinntt88 --mmaammxx--bbff1166 --mmuuiinnttrr --mmhhrreesseett --mmaavvxxvvnnnnii --mmaavvxx551122ffpp1166 --mmccllddeemmoottee --mmmmss--bbiittffiieellddss --mmnnoo--aalliiggnn--ssttrriinnggooppss --mmiinnlliinnee--aallll--ssttrriinnggooppss --mmiinnlliinnee--ssttrriinnggooppss--ddyy-- nnaammiiccaallllyy --mmssttrriinnggoopp--ssttrraatteeggyy==_a_l_g --mmkkll --mmwwiiddeekkll --mmmmeemmccppyy--ssttrraatt-- eeggyy==_s_t_r_a_t_e_g_y --mmmmeemmsseett--ssttrraatteeggyy==_s_t_r_a_t_e_g_y --mmppuusshh--aarrggss --mmaaccccuummuu-- llaattee--oouuttggooiinngg--aarrggss --mm112288bbiitt--lloonngg--ddoouubbllee --mm9966bbiitt--lloonngg--ddoouubbllee --mmlloonngg--ddoouubbllee--6644 --mmlloonngg--ddoouubbllee--8800 --mmlloonngg--ddoouubbllee--112288 --mmrreeggppaarrmm==_n_u_m --mmsssseerreeggppaarrmm --mmvveecclliibbaabbii==_t_y_p_e --mmvveecctt88--rreett--iinn--mmeemm --mmppcc3322 --mmppcc6644 --mmppcc8800 --mmssttaacckkrreeaalliiggnn --mmoommiitt--lleeaaff--ffrraammee--ppooiinntteerr --mmnnoo--rreedd--zzoonnee --mmnnoo--ttllss--ddiirreecctt--sseegg--rreeffss --mmccmmooddeell==_c_o_d_e_-_m_o_d_e_l --mmaabbii==_n_a_m_e --mmaadd-- ddrreessss--mmooddee==_m_o_d_e --mm3322 --mm6644 --mmxx3322 --mm1166 --mmiiaammccuu --mmllaarrggee--ddaattaa--tthhrreesshhoolldd==_n_u_m --mmssssee22aavvxx --mmffeennttrryy --mmrreeccoorrdd--mmccoouunntt --mmnnoopp--mmccoouunntt --mm88bbiitt--iiddiivv --mmiinnssttrruummeenntt--rreettuurrnn==_t_y_p_e --mmffeenn-- ttrryy--nnaammee==_n_a_m_e --mmffeennttrryy--sseeccttiioonn==_n_a_m_e --mmaavvxx225566--sspplliitt--uunnaalliiggnneedd--llooaadd --mmaavvxx225566--sspplliitt--uunnaalliiggnneedd--ssttoorree --mmaalliiggnn--ddaattaa==_t_y_p_e --mmssttaacckk--pprrootteecc-- ttoorr--gguuaarrdd==_g_u_a_r_d --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--rreegg==_r_e_g --mmssttaacckk--pprrootteecc-- ttoorr--gguuaarrdd--ooffffsseett==_o_f_f_s_e_t --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ssyymmbbooll==_s_y_m_b_o_l --mmggeenneerraall--rreeggss--oonnllyy --mmccaallll--mmss22ssyyssvv--xxlloogguueess --mmrreellaaxx--ccmmppxxcchhgg--lloooopp --mmiinnddiirreecctt--bbrraanncchh==_c_h_o_i_c_e --mmffuunnccttiioonn--rreettuurrnn==_c_h_o_i_c_e --mmiinnddii-- rreecctt--bbrraanncchh--rreeggiisstteerr --mmhhaarrddeenn--ssllss==_c_h_o_i_c_e --mmiinnddiirreecctt--bbrraanncchh--ccss--pprree-- ffiixx --mmnneeeeddeedd --mmnnoo--ddiirreecctt--eexxtteerrnn--aacccceessss _x_8_6 _W_i_n_d_o_w_s _O_p_t_i_o_n_s --mmccoonnssoollee --mmccyyggwwiinn --mmnnoo--ccyyggwwiinn --mmddllll --mmnnoopp--ffuunn--ddlllliimmppoorrtt --mmtthhrreeaadd --mmuunniiccooddee --mmwwiinn3322 --mmwwiinnddoowwss --ffnnoo--sseett--ssttaacckk--eexxeeccuuttaabbllee _X_s_t_o_r_m_y_1_6 _O_p_t_i_o_n_s --mmssiimm _X_t_e_n_s_a _O_p_t_i_o_n_s --mmccoonnsstt1166 --mmnnoo--ccoonnsstt1166 --mmffuusseedd--mmaadddd --mmnnoo--ffuusseedd--mmaadddd --mmffoorrccee--nnoo--ppiicc --mmsseerriiaalliizzee--vvoollaattiillee --mmnnoo--sseerriiaall-- iizzee--vvoollaattiillee --mmtteexxtt--sseeccttiioonn--lliitteerraallss --mmnnoo--tteexxtt--sseeccttiioonn--lliitteerraallss --mmaauuttoo--lliittppoooollss --mmnnoo--aauuttoo--lliittppoooollss --mmttaarrggeett--aalliiggnn --mmnnoo--ttaarr-- ggeett--aalliiggnn --mmlloonnggccaallllss --mmnnoo--lloonnggccaallllss --mmaabbii==_a_b_i_-_t_y_p_e _z_S_e_r_i_e_s _O_p_t_i_o_n_s See S/390 and zSeries Options. OOppttiioonnss CCoonnttrroolllliinngg tthhee KKiinndd ooff OOuuttppuutt Compilation can involve up to four stages: preprocessing, compilation proper, assembly and linking, always in that order. GCC is capable of preprocessing and compiling several files either into several assembler input files, or into one assembler input file; then each assembler in- put file produces an object file, and linking combines all the object files (those newly compiled, and those specified as input) into an exe- cutable file. For any given input file, the file name suffix determines what kind of compilation is done: _f_i_l_e..cc C source code that must be preprocessed. _f_i_l_e..ii C source code that should not be preprocessed. _f_i_l_e..iiii C++ source code that should not be preprocessed. _f_i_l_e..mm Objective-C source code. Note that you must link with the _l_i_b_o_b_j_c library to make an Objective-C program work. _f_i_l_e..mmii Objective-C source code that should not be preprocessed. _f_i_l_e..mmmm _f_i_l_e..MM Objective-C++ source code. Note that you must link with the _l_i_- _b_o_b_j_c library to make an Objective-C++ program work. Note that ..MM refers to a literal capital M. _f_i_l_e..mmiiii Objective-C++ source code that should not be preprocessed. _f_i_l_e..hh C, C++, Objective-C or Objective-C++ header file to be turned into a precompiled header (default), or C, C++ header file to be turned into an Ada spec (via the --ffdduummpp--aaddaa--ssppeecc switch). _f_i_l_e..cccc _f_i_l_e..ccpp _f_i_l_e..ccxxxx _f_i_l_e..ccpppp _f_i_l_e..CCPPPP _f_i_l_e..cc++++ _f_i_l_e..CC C++ source code that must be preprocessed. Note that in ..ccxxxx, the last two letters must both be literally xx. Likewise, ..CC refers to a literal capital C. _f_i_l_e..mmmm _f_i_l_e..MM Objective-C++ source code that must be preprocessed. _f_i_l_e..mmiiii Objective-C++ source code that should not be preprocessed. _f_i_l_e..hhhh _f_i_l_e..HH _f_i_l_e..hhpp _f_i_l_e..hhxxxx _f_i_l_e..hhpppp _f_i_l_e..HHPPPP _f_i_l_e..hh++++ _f_i_l_e..ttcccc C++ header file to be turned into a precompiled header or Ada spec. _f_i_l_e..ff _f_i_l_e..ffoorr _f_i_l_e..ffttnn Fixed form Fortran source code that should not be preprocessed. _f_i_l_e..FF _f_i_l_e..FFOORR _f_i_l_e..ffpppp _f_i_l_e..FFPPPP _f_i_l_e..FFTTNN Fixed form Fortran source code that must be preprocessed (with the traditional preprocessor). _f_i_l_e..ff9900 _f_i_l_e..ff9955 _f_i_l_e..ff0033 _f_i_l_e..ff0088 Free form Fortran source code that should not be preprocessed. _f_i_l_e..FF9900 _f_i_l_e..FF9955 _f_i_l_e..FF0033 _f_i_l_e..FF0088 Free form Fortran source code that must be preprocessed (with the traditional preprocessor). _f_i_l_e..ggoo Go source code. _f_i_l_e..dd D source code. _f_i_l_e..ddii D interface file. _f_i_l_e..dddd D documentation code (Ddoc). _f_i_l_e..aaddss Ada source code file that contains a library unit declaration (a declaration of a package, subprogram, or generic, or a generic in- stantiation), or a library unit renaming declaration (a package, generic, or subprogram renaming declaration). Such files are also called _s_p_e_c_s. _f_i_l_e..aaddbb Ada source code file containing a library unit body (a subprogram or package body). Such files are also called _b_o_d_i_e_s. _f_i_l_e..ss Assembler code. _f_i_l_e..SS _f_i_l_e..ssxx Assembler code that must be preprocessed. _o_t_h_e_r An object file to be fed straight into linking. Any file name with no recognized suffix is treated this way. You can specify the input language explicitly with the --xx option: --xx _l_a_n_g_u_a_g_e Specify explicitly the _l_a_n_g_u_a_g_e for the following input files (rather than letting the compiler choose a default based on the file name suffix). This option applies to all following input files until the next --xx option. Possible values for _l_a_n_g_u_a_g_e are: c c-header cpp-output c++ c++-header c++-system-header c++-user-header c++-cpp-output objective-c objective-c-header objective-c-cpp-output objective-c++ objective-c++-header objective-c++-cpp-output assembler assembler-with-cpp ada d f77 f77-cpp-input f95 f95-cpp-input go --xx nnoonnee Turn off any specification of a language, so that subsequent files are handled according to their file name suffixes (as they are if --xx has not been used at all). If you only want some of the stages of compilation, you can use --xx (or filename suffixes) to tell ggcccc where to start, and one of the options --cc, --SS, or --EE to say where ggcccc is to stop. Note that some combinations (for example, --xx ccpppp--oouuttppuutt --EE) instruct ggcccc to do nothing at all. --cc Compile or assemble the source files, but do not link. The linking stage simply is not done. The ultimate output is in the form of an object file for each source file. By default, the object file name for a source file is made by re- placing the suffix ..cc, ..ii, ..ss, etc., with ..oo. Unrecognized input files, not requiring compilation or assembly, are ignored. --SS Stop after the stage of compilation proper; do not assemble. The output is in the form of an assembler code file for each non-assem- bler input file specified. By default, the assembler file name for a source file is made by replacing the suffix ..cc, ..ii, etc., with ..ss. Input files that don't require compilation are ignored. --EE Stop after the preprocessing stage; do not run the compiler proper. The output is in the form of preprocessed source code, which is sent to the standard output. Input files that don't require preprocessing are ignored. --oo _f_i_l_e Place the primary output in file _f_i_l_e. This applies to whatever sort of output is being produced, whether it be an executable file, an object file, an assembler file or preprocessed C code. If --oo is not specified, the default is to put an executable file in _a_._o_u_t, the object file for _s_o_u_r_c_e_._s_u_f_f_i_x in _s_o_u_r_c_e_._o, its assembler file in _s_o_u_r_c_e_._s, a precompiled header file in _s_o_u_r_c_e_._s_u_f_f_i_x_._g_c_h, and all preprocessed C source on standard output. Though --oo names only the primary output, it also affects the naming of auxiliary and dump outputs. See the examples below. Unless overridden, both auxiliary outputs and dump outputs are placed in the same directory as the primary output. In auxiliary outputs, the suffix of the input file is replaced with that of the auxiliary output file type; in dump outputs, the suffix of the dump file is appended to the input file suffix. In compilation commands, the base name of both auxiliary and dump outputs is that of the primary output; in compile and link commands, the primary output name, mi- nus the executable suffix, is combined with the input file name. If both share the same base name, disregarding the suffix, the re- sult of the combination is that base name, otherwise, they are con- catenated, separated by a dash. gcc -c foo.c ... will use _f_o_o_._o as the primary output, and place aux outputs and dumps next to it, e.g., aux file _f_o_o_._d_w_o for --ggsspplliitt--ddwwaarrff, and dump file _f_o_o_._c_._?_?_?_r_._f_i_n_a_l for --ffdduummpp--rrttll--ffiinnaall. If a non-linker output file is explicitly specified, aux and dump files by default take the same base name: gcc -c foo.c -o dir/foobar.o ... will name aux outputs _d_i_r_/_f_o_o_b_a_r_._* and dump outputs _d_i_r_/_f_o_o_b_a_r_._c_._*. A linker output will instead prefix aux and dump outputs: gcc foo.c bar.c -o dir/foobar ... will generally name aux outputs _d_i_r_/_f_o_o_b_a_r_-_f_o_o_._* and _d_i_r_/_f_o_o_- _b_a_r_-_b_a_r_._*, and dump outputs _d_i_r_/_f_o_o_b_a_r_-_f_o_o_._c_._* and _d_i_r_/_f_o_o_- _b_a_r_-_b_a_r_._c_._*. The one exception to the above is when the executable shares the base name with the single input: gcc foo.c -o dir/foo ... in which case aux outputs are named _d_i_r_/_f_o_o_._* and dump outputs named _d_i_r_/_f_o_o_._c_._*. The location and the names of auxiliary and dump outputs can be ad- justed by the options --dduummppbbaassee, --dduummppbbaassee--eexxtt, --dduummppddiirr, --ssaavvee--tteemmppss==ccwwdd, and --ssaavvee--tteemmppss==oobbjj. --dduummppbbaassee _d_u_m_p_b_a_s_e This option sets the base name for auxiliary and dump output files. It does not affect the name of the primary output file. Intermedi- ate outputs, when preserved, are not regarded as primary outputs, but as auxiliary outputs: gcc -save-temps -S foo.c saves the (no longer) temporary preprocessed file in _f_o_o_._i, and then compiles to the (implied) output file _f_o_o_._s, whereas: gcc -save-temps -dumpbase save-foo -c foo.c preprocesses to in _s_a_v_e_-_f_o_o_._i, compiles to _s_a_v_e_-_f_o_o_._s (now an in- termediate, thus auxiliary output), and then assembles to the (im- plied) output file _f_o_o_._o. Absent this option, dump and aux files take their names from the input file, or from the (non-linker) output file, if one is explic- itly specified: dump output files (e.g. those requested by --ffdduummpp--** options) with the input name suffix, and aux output files (those requested by other non-dump options, e.g. "-save-temps", "-gsplit-dwarf", "-fcallgraph-info") without it. Similar suffix differentiation of dump and aux outputs can be at- tained for explicitly-given --dduummppbbaassee bbaasseennaammee..ssuuff by also specify- ing --dduummppbbaassee--eexxtt ..ssuuff. If _d_u_m_p_b_a_s_e is explicitly specified with any directory component, any _d_u_m_p_p_f_x specification (e.g. --dduummppddiirr or --ssaavvee--tteemmppss==**) is ig- nored, and instead of appending to it, _d_u_m_p_b_a_s_e fully overrides it: gcc foo.c -c -o dir/foo.o -dumpbase alt/foo \ -dumpdir pfx- -save-temps=cwd ... creates auxiliary and dump outputs named _a_l_t_/_f_o_o_._*, disregarding _d_i_r_/ in --oo, the _._/ prefix implied by --ssaavvee--tteemmppss==ccwwdd, and _p_f_x_- in --dduummppddiirr. When --dduummppbbaassee is specified in a command that compiles multiple in- puts, or that compiles and then links, it may be combined with _d_u_m_p_p_f_x, as specified under --dduummppddiirr. Then, each input file is compiled using the combined _d_u_m_p_p_f_x, and default values for _d_u_m_p_- _b_a_s_e and _a_u_x_d_r_o_p_s_u_f are computed for each input file: gcc foo.c bar.c -c -dumpbase main ... creates _f_o_o_._o and _b_a_r_._o as primary outputs, and avoids overwriting the auxiliary and dump outputs by using the _d_u_m_p_b_a_s_e as a prefix, creating auxiliary and dump outputs named _m_a_i_n_-_f_o_o_._* and _m_a_i_n_-_b_a_r_._*. An empty string specified as _d_u_m_p_b_a_s_e avoids the influence of the output basename in the naming of auxiliary and dump outputs during compilation, computing default values : gcc -c foo.c -o dir/foobar.o -dumpbase " ... will name aux outputs _d_i_r_/_f_o_o_._* and dump outputs _d_i_r_/_f_o_o_._c_._*. Note how their basenames are taken from the input name, but the direc- tory still defaults to that of the output. The empty-string dumpbase does not prevent the use of the output basename for outputs during linking: gcc foo.c bar.c -o dir/foobar -dumpbase " -flto ... The compilation of the source files will name auxiliary outputs _d_i_r_/_f_o_o_._* and _d_i_r_/_b_a_r_._*, and dump outputs _d_i_r_/_f_o_o_._c_._* and _d_i_r_/_b_a_r_._c_._*. LTO recompilation during linking will use _d_i_r_/_f_o_o_b_a_r_. as the prefix for dumps and auxiliary files. --dduummppbbaassee--eexxtt _a_u_x_d_r_o_p_s_u_f When forming the name of an auxiliary (but not a dump) output file, drop trailing _a_u_x_d_r_o_p_s_u_f from _d_u_m_p_b_a_s_e before appending any suf- fixes. If not specified, this option defaults to the suffix of a default _d_u_m_p_b_a_s_e, i.e., the suffix of the input file when --dduummppbbaassee is not present in the command line, or _d_u_m_p_b_a_s_e is combined with _d_u_m_p_p_f_x. gcc foo.c -c -o dir/foo.o -dumpbase x-foo.c -dumpbase-ext .c ... creates _d_i_r_/_f_o_o_._o as the main output, and generates auxiliary out- puts in _d_i_r_/_x_-_f_o_o_._*, taking the location of the primary output, and dropping the _._c suffix from the _d_u_m_p_b_a_s_e. Dump outputs retain the suffix: _d_i_r_/_x_-_f_o_o_._c_._*. This option is disregarded if it does not match the suffix of a specified _d_u_m_p_b_a_s_e, except as an alternative to the executable suf- fix when appending the linker output base name to _d_u_m_p_p_f_x, as spec- ified below: gcc foo.c bar.c -o main.out -dumpbase-ext .out ... creates _m_a_i_n_._o_u_t as the primary output, and avoids overwriting the auxiliary and dump outputs by using the executable name minus _a_u_x_- _d_r_o_p_s_u_f as a prefix, creating auxiliary outputs named _m_a_i_n_-_f_o_o_._* and _m_a_i_n_-_b_a_r_._* and dump outputs named _m_a_i_n_-_f_o_o_._c_._* and _m_a_i_n_-_b_a_r_._c_._*. --dduummppddiirr _d_u_m_p_p_f_x When forming the name of an auxiliary or dump output file, use _d_u_m_p_p_f_x as a prefix: gcc -dumpdir pfx- -c foo.c ... creates _f_o_o_._o as the primary output, and auxiliary outputs named _p_f_x_-_f_o_o_._*, combining the given _d_u_m_p_p_f_x with the default _d_u_m_p_b_a_s_e derived from the default primary output, derived in turn from the input name. Dump outputs also take the input name suffix: _p_f_x_-_f_o_o_._c_._*. If _d_u_m_p_p_f_x is to be used as a directory name, it must end with a directory separator: gcc -dumpdir dir/ -c foo.c -o obj/bar.o ... creates _o_b_j_/_b_a_r_._o as the primary output, and auxiliary outputs named _d_i_r_/_b_a_r_._*, combining the given _d_u_m_p_p_f_x with the default _d_u_m_p_- _b_a_s_e derived from the primary output name. Dump outputs also take the input name suffix: _d_i_r_/_b_a_r_._c_._*. It defaults to the location of the output file, unless the output file is a special file like "/dev/null". Options --ssaavvee--tteemmppss==ccwwdd and --ssaavvee--tteemmppss==oobbjj override this default, just like an explicit --dduummppddiirr option. In case multiple such options are given, the last one prevails: gcc -dumpdir pfx- -c foo.c -save-temps=obj ... outputs _f_o_o_._o, with auxiliary outputs named _f_o_o_._* because --ssaavvee--tteemmppss==** overrides the _d_u_m_p_p_f_x given by the earlier --dduummppddiirr option. It does not matter that ==oobbjj is the default for --ssaavvee--tteemmppss, nor that the output directory is implicitly the cur- rent directory. Dump outputs are named _f_o_o_._c_._*. When compiling from multiple input files, if --dduummppbbaassee is speci- fied, _d_u_m_p_b_a_s_e, minus a _a_u_x_d_r_o_p_s_u_f suffix, and a dash are appended to (or override, if containing any directory components) an ex- plicit or defaulted _d_u_m_p_p_f_x, so that each of the multiple compila- tions gets differently-named aux and dump outputs. gcc foo.c bar.c -c -dumpdir dir/pfx- -dumpbase main ... outputs auxiliary dumps to _d_i_r_/_p_f_x_-_m_a_i_n_-_f_o_o_._* and _d_i_r_/_p_f_x_-_m_a_i_n_-_b_a_r_._*, appending _d_u_m_p_b_a_s_e- to _d_u_m_p_p_f_x. Dump outputs retain the input file suffix: _d_i_r_/_p_f_x_-_m_a_i_n_-_f_o_o_._c_._* and _d_i_r_/_p_f_x_-_m_a_i_n_-_b_a_r_._c_._*, respectively. Contrast with the single-input compilation: gcc foo.c -c -dumpdir dir/pfx- -dumpbase main ... that, applying --dduummppbbaassee to a single source, does not compute and append a separate _d_u_m_p_b_a_s_e per input file. Its auxiliary and dump outputs go in _d_i_r_/_p_f_x_-_m_a_i_n_._*. When compiling and then linking from multiple input files, a de- faulted or explicitly specified _d_u_m_p_p_f_x also undergoes the _d_u_m_p_- _b_a_s_e- transformation above (e.g. the compilation of _f_o_o_._c and _b_a_r_._c above, but without --cc). If neither --dduummppddiirr nor --dduummppbbaassee are given, the linker output base name, minus _a_u_x_d_r_o_p_s_u_f, if specified, or the executable suffix otherwise, plus a dash is appended to the default _d_u_m_p_p_f_x instead. Note, however, that unlike earlier cases of linking: gcc foo.c bar.c -dumpdir dir/pfx- -o main ... does not append the output name _m_a_i_n to _d_u_m_p_p_f_x, because --dduummppddiirr is explicitly specified. The goal is that the explicitly-specified _d_u_m_p_p_f_x may contain the specified output name as part of the pre- fix, if desired; only an explicitly-specified --dduummppbbaassee would be combined with it, in order to avoid simply discarding a meaningful option. When compiling and then linking from a single input file, the linker output base name will only be appended to the default _d_u_m_p_p_f_x as above if it does not share the base name with the single input file name. This has been covered in single-input linking cases above, but not with an explicit --dduummppddiirr that inhibits the combination, even if overridden by --ssaavvee--tteemmppss==**: gcc foo.c -dumpdir alt/pfx- -o dir/main.exe -save-temps=cwd ... Auxiliary outputs are named _f_o_o_._*, and dump outputs _f_o_o_._c_._*, in the current working directory as ultimately requested by --ssaavvee--tteemmppss==ccwwdd. Summing it all up for an intuitive though slightly imprecise data flow: the primary output name is broken into a directory part and a basename part; _d_u_m_p_p_f_x is set to the former, unless overridden by --dduummppddiirr or --ssaavvee--tteemmppss==**, and _d_u_m_p_b_a_s_e is set to the latter, un- less overriden by --dduummppbbaassee. If there are multiple inputs or link- ing, this _d_u_m_p_b_a_s_e may be combined with _d_u_m_p_p_f_x and taken from each input file. Auxiliary output names for each input are formed by combining _d_u_m_p_p_f_x, _d_u_m_p_b_a_s_e minus suffix, and the auxiliary output suffix; dump output names are only different in that the suffix from _d_u_m_p_b_a_s_e is retained. When it comes to auxiliary and dump outputs created during LTO re- compilation, a combination of _d_u_m_p_p_f_x and _d_u_m_p_b_a_s_e, as given or as derived from the linker output name but not from inputs, even in cases in which this combination would not otherwise be used as such, is passed down with a trailing period replacing the compiler- added dash, if any, as a --dduummppddiirr option to llttoo--wwrraappppeerr; being in- volved in linking, this program does not normally get any --dduummppbbaassee and --dduummppbbaassee--eexxtt, and it ignores them. When running sub-compilers, llttoo--wwrraappppeerr appends LTO stage names to the received _d_u_m_p_p_f_x, ensures it contains a directory component so that it overrides any --dduummppddiirr, and passes that as --dduummppbbaassee to sub-compilers. --vv Print (on standard error output) the commands executed to run the stages of compilation. Also print the version number of the com- piler driver program and of the preprocessor and the compiler proper. --###### Like --vv except the commands are not executed and arguments are quoted unless they contain only alphanumeric characters or "./-_". This is useful for shell scripts to capture the driver-generated command lines. ----hheellpp Print (on the standard output) a description of the command-line options understood by ggcccc. If the --vv option is also specified then ----hheellpp is also passed on to the various processes invoked by ggcccc, so that they can display the command-line options they accept. If the --WWeexxttrraa option has also been specified (prior to the ----hheellpp op- tion), then command-line options that have no documentation associ- ated with them are also displayed. ----ttaarrggeett--hheellpp Print (on the standard output) a description of target-specific command-line options for each tool. For some targets extra target- specific information may also be printed. ----hheellpp=={{_c_l_a_s_s|[^^]_q_u_a_l_i_f_i_e_r}}[,,......] Print (on the standard output) a description of the command-line options understood by the compiler that fit into all specified classes and qualifiers. These are the supported classes: ooppttiimmiizzeerrss Display all of the optimization options supported by the com- piler. wwaarrnniinnggss Display all of the options controlling warning messages pro- duced by the compiler. ttaarrggeett Display target-specific options. Unlike the ----ttaarrggeett--hheellpp op- tion however, target-specific options of the linker and assem- bler are not displayed. This is because those tools do not currently support the extended ----hheellpp== syntax. ppaarraammss Display the values recognized by the ----ppaarraamm option. _l_a_n_g_u_a_g_e Display the options supported for _l_a_n_g_u_a_g_e, where _l_a_n_g_u_a_g_e is the name of one of the languages supported in this version of GCC. If an option is supported by all languages, one needs to select ccoommmmoonn class. ccoommmmoonn Display the options that are common to all languages. These are the supported qualifiers: uunnddooccuummeenntteedd Display only those options that are undocumented. jjooiinneedd Display options taking an argument that appears after an equal sign in the same continuous piece of text, such as: ----hheellpp==ttaarr-- ggeett. sseeppaarraattee Display options taking an argument that appears as a separate word following the original option, such as: --oo oouuttppuutt--ffiillee. Thus for example to display all the undocumented target-specific switches supported by the compiler, use: --help=target,undocumented The sense of a qualifier can be inverted by prefixing it with the ^^ character, so for example to display all binary warning options (i.e., ones that are either on or off and that do not take an argu- ment) that have a description, use: --help=warnings,^joined,^undocumented The argument to ----hheellpp== should not consist solely of inverted qual- ifiers. Combining several classes is possible, although this usually re- stricts the output so much that there is nothing to display. One case where it does work, however, is when one of the classes is _t_a_r_g_e_t. For example, to display all the target-specific optimiza- tion options, use: --help=target,optimizers The ----hheellpp== option can be repeated on the command line. Each suc- cessive use displays its requested class of options, skipping those that have already been displayed. If ----hheellpp is also specified any- where on the command line then this takes precedence over any ----hheellpp== option. If the --QQ option appears on the command line before the ----hheellpp== op- tion, then the descriptive text displayed by ----hheellpp== is changed. Instead of describing the displayed options, an indication is given as to whether the option is enabled, disabled or set to a specific value (assuming that the compiler knows this at the point where the ----hheellpp== option is used). Here is a truncated example from the ARM port of ggcccc: % gcc -Q -mabi=2 --help=target -c The following options are target specific: -mabi= 2 -mabort-on-noreturn [disabled] -mapcs [disabled] The output is sensitive to the effects of previous command-line op- tions, so for example it is possible to find out which optimiza- tions are enabled at --OO22 by using: -Q -O2 --help=optimizers Alternatively you can discover which binary optimizations are en- abled by --OO33 by using: gcc -c -Q -O3 --help=optimizers > /tmp/O3-opts gcc -c -Q -O2 --help=optimizers > /tmp/O2-opts diff /tmp/O2-opts /tmp/O3-opts | grep enabled ----vveerrssiioonn Display the version number and copyrights of the invoked GCC. --ppaassss--eexxiitt--ccooddeess Normally the ggcccc program exits with the code of 1 if any phase of the compiler returns a non-success return code. If you specify --ppaassss--eexxiitt--ccooddeess, the ggcccc program instead returns with the numeri- cally highest error produced by any phase returning an error indi- cation. The C, C++, and Fortran front ends return 4 if an internal compiler error is encountered. --ppiippee Use pipes rather than temporary files for communication between the various stages of compilation. This fails to work on some systems where the assembler is unable to read from a pipe; but the GNU as- sembler has no trouble. --ssppeeccss==_f_i_l_e Process _f_i_l_e after the compiler reads in the standard _s_p_e_c_s file, in order to override the defaults which the ggcccc driver program uses when determining what switches to pass to cccc11, cccc11pplluuss, aass, lldd, etc. More than one --ssppeeccss==_f_i_l_e can be specified on the command line, and they are processed in order, from left to right. --wwrraappppeerr Invoke all subcommands under a wrapper program. The name of the wrapper program and its parameters are passed as a comma separated list. gcc -c t.c -wrapper gdb,--args This invokes all subprograms of ggcccc under ggddbb ----aarrggss, thus the in- vocation of cccc11 is ggddbb ----aarrggss cccc11 ....... --ffffiillee--pprreeffiixx--mmaapp==_o_l_d==_n_e_w When compiling files residing in directory _o_l_d, record any refer- ences to them in the result of the compilation as if the files resided in directory _n_e_w instead. Specifying this option is equiv- alent to specifying all the individual --ff**--pprreeffiixx--mmaapp options. This can be used to make reproducible builds that are location in- dependent. See also --ffmmaaccrroo--pprreeffiixx--mmaapp, --ffddeebbuugg--pprreeffiixx--mmaapp and --ffpprrooffiillee--pprreeffiixx--mmaapp. --ffpplluuggiinn==_n_a_m_e..ssoo Load the plugin code in file _n_a_m_e.so, assumed to be a shared object to be dlopen'd by the compiler. The base name of the shared object file is used to identify the plugin for the purposes of argument parsing (See --ffpplluuggiinn--aarrgg--_n_a_m_e--_k_e_y==_v_a_l_u_e below). Each plugin should define the callback functions specified in the Plugins API. --ffpplluuggiinn--aarrgg--_n_a_m_e--_k_e_y==_v_a_l_u_e Define an argument called _k_e_y with a value of _v_a_l_u_e for the plugin called _n_a_m_e. --ffdduummpp--aaddaa--ssppeecc[--sslliimm] For C and C++ source and include files, generate corresponding Ada specs. --ffaaddaa--ssppeecc--ppaarreenntt==_u_n_i_t In conjunction with --ffdduummpp--aaddaa--ssppeecc[--sslliimm] above, generate Ada specs as child units of parent _u_n_i_t. --ffdduummpp--ggoo--ssppeecc==_f_i_l_e For input files in any language, generate corresponding Go declara- tions in _f_i_l_e. This generates Go "const", "type", "var", and "func" declarations which may be a useful way to start writing a Go interface to code written in some other language. @@_f_i_l_e Read command-line options from _f_i_l_e. The options read are inserted in place of the original @_f_i_l_e option. If _f_i_l_e does not exist, or cannot be read, then the option will be treated literally, and not removed. Options in _f_i_l_e are separated by whitespace. A whitespace charac- ter may be included in an option by surrounding the entire option in either single or double quotes. Any character (including a backslash) may be included by prefixing the character to be in- cluded with a backslash. The _f_i_l_e may itself contain additional @_f_i_l_e options; any such options will be processed recursively. CCoommppiilliinngg CC++++ PPrrooggrraammss C++ source files conventionally use one of the suffixes ..CC, ..cccc, ..ccpppp, ..CCPPPP, ..cc++++, ..ccpp, or ..ccxxxx; C++ header files often use ..hhhh, ..hhpppp, ..HH, or (for shared template code) ..ttcccc; and preprocessed C++ files use the suffix ..iiii. GCC recognizes files with these names and compiles them as C++ programs even if you call the compiler the same way as for compil- ing C programs (usually with the name ggcccc). However, the use of ggcccc does not add the C++ library. gg++++ is a program that calls GCC and automatically specifies linking against the C++ li- brary. It treats ..cc, ..hh and ..ii files as C++ source files instead of C source files unless --xx is used. This program is also useful when pre- compiling a C header file with a ..hh extension for use in C++ compila- tions. On many systems, gg++++ is also installed with the name cc++++. When you compile C++ programs, you may specify many of the same com- mand-line options that you use for compiling programs in any language; or command-line options meaningful for C and related languages; or op- tions that are meaningful only for C++ programs. OOppttiioonnss CCoonnttrroolllliinngg CC DDiiaalleecctt The following options control the dialect of C (or languages derived from C, such as C++, Objective-C and Objective-C++) that the compiler accepts: --aannssii In C mode, this is equivalent to --ssttdd==cc9900. In C++ mode, it is equivalent to --ssttdd==cc++++9988. This turns off certain features of GCC that are incompatible with ISO C90 (when compiling C code), or of standard C++ (when compiling C++ code), such as the "asm" and "typeof" keywords, and predefined macros such as "unix" and "vax" that identify the type of system you are using. It also enables the undesirable and rarely used ISO trigraph feature. For the C compiler, it disables recognition of C++ style //// comments as well as the "inline" keyword. The alternate keywords "__asm__", "__extension__", "__inline__" and "__typeof__" continue to work despite --aannssii. You would not want to use them in an ISO C program, of course, but it is useful to put them in header files that might be included in compilations done with --aannssii. Alternate predefined macros such as "__unix__" and "__vax__" are also available, with or without --aannssii. The --aannssii option does not cause non-ISO programs to be rejected gratuitously. For that, --WWppeeddaannttiicc is required in addition to --aannssii. The macro "__STRICT_ANSI__" is predefined when the --aannssii option is used. Some header files may notice this macro and refrain from declaring certain functions or defining certain macros that the ISO standard doesn't call for; this is to avoid interfering with any programs that might use these names for other things. Functions that are normally built in but do not have semantics de- fined by ISO C (such as "alloca" and "ffs") are not built-in func- tions when --aannssii is used. --ssttdd== Determine the language standard. This option is currently only supported when compiling C or C++. The compiler can accept several base standards, such as cc9900 or cc++++9988, and GNU dialects of those standards, such as ggnnuu9900 or ggnnuu++++9988. When a base standard is specified, the compiler accepts all programs following that standard plus those using GNU exten- sions that do not contradict it. For example, --ssttdd==cc9900 turns off certain features of GCC that are incompatible with ISO C90, such as the "asm" and "typeof" keywords, but not other GNU extensions that do not have a meaning in ISO C90, such as omitting the middle term of a "?:" expression. On the other hand, when a GNU dialect of a standard is specified, all features supported by the compiler are enabled, even when those features change the meaning of the base standard. As a result, some strict-conforming programs may be re- jected. The particular standard is used by --WWppeeddaannttiicc to identify which features are GNU extensions given that version of the stan- dard. For example --ssttdd==ggnnuu9900 --WWppeeddaannttiicc warns about C++ style //// comments, while --ssttdd==ggnnuu9999 --WWppeeddaannttiicc does not. A value for this option must be provided; possible values are cc9900 cc8899 iissoo99889999::11999900 Support all ISO C90 programs (certain GNU extensions that con- flict with ISO C90 are disabled). Same as --aannssii for C code. iissoo99889999::119999440099 ISO C90 as modified in amendment 1. cc9999 cc99xx iissoo99889999::11999999 iissoo99889999::119999xx ISO C99. This standard is substantially completely supported, modulo bugs and floating-point issues (mainly but not entirely relating to optional C99 features from Annexes F and G). See for more information. The names cc99xx and iissoo99889999::119999xx are deprecated. cc1111 cc11xx iissoo99889999::22001111 ISO C11, the 2011 revision of the ISO C standard. This stan- dard is substantially completely supported, modulo bugs, float- ing-point issues (mainly but not entirely relating to optional C11 features from Annexes F and G) and the optional Annexes K (Bounds-checking interfaces) and L (Analyzability). The name cc11xx is deprecated. cc1177 cc1188 iissoo99889999::22001177 iissoo99889999::22001188 ISO C17, the 2017 revision of the ISO C standard (published in 2018). This standard is same as C11 except for corrections of defects (all of which are also applied with --ssttdd==cc1111) and a new value of "__STDC_VERSION__", and so is supported to the same extent as C11. cc22xx The next version of the ISO C standard, still under develop- ment. The support for this version is experimental and incom- plete. ggnnuu9900 ggnnuu8899 GNU dialect of ISO C90 (including some C99 features). ggnnuu9999 ggnnuu99xx GNU dialect of ISO C99. The name ggnnuu99xx is deprecated. ggnnuu1111 ggnnuu11xx GNU dialect of ISO C11. The name ggnnuu11xx is deprecated. ggnnuu1177 ggnnuu1188 GNU dialect of ISO C17. This is the default for C code. ggnnuu22xx The next version of the ISO C standard, still under develop- ment, plus GNU extensions. The support for this version is ex- perimental and incomplete. cc++++9988 cc++++0033 The 1998 ISO C++ standard plus the 2003 technical corrigendum and some additional defect reports. Same as --aannssii for C++ code. ggnnuu++++9988 ggnnuu++++0033 GNU dialect of --ssttdd==cc++++9988. cc++++1111 cc++++00xx The 2011 ISO C++ standard plus amendments. The name cc++++00xx is deprecated. ggnnuu++++1111 ggnnuu++++00xx GNU dialect of --ssttdd==cc++++1111. The name ggnnuu++++00xx is deprecated. cc++++1144 cc++++11yy The 2014 ISO C++ standard plus amendments. The name cc++++11yy is deprecated. ggnnuu++++1144 ggnnuu++++11yy GNU dialect of --ssttdd==cc++++1144. The name ggnnuu++++11yy is deprecated. cc++++1177 cc++++11zz The 2017 ISO C++ standard plus amendments. The name cc++++11zz is deprecated. ggnnuu++++1177 ggnnuu++++11zz GNU dialect of --ssttdd==cc++++1177. This is the default for C++ code. The name ggnnuu++++11zz is deprecated. cc++++2200 cc++++22aa The 2020 ISO C++ standard plus amendments. Support is experi- mental, and could change in incompatible ways in future re- leases. The name cc++++22aa is deprecated. ggnnuu++++2200 ggnnuu++++22aa GNU dialect of --ssttdd==cc++++2200. Support is experimental, and could change in incompatible ways in future releases. The name ggnnuu++++22aa is deprecated. cc++++22bb cc++++2233 The next revision of the ISO C++ standard, planned for 2023. Support is highly experimental, and will almost certainly change in incompatible ways in future releases. ggnnuu++++22bb ggnnuu++++2233 GNU dialect of --ssttdd==cc++++22bb. Support is highly experimental, and will almost certainly change in incompatible ways in future re- leases. --aauuxx--iinnffoo _f_i_l_e_n_a_m_e Output to the given filename prototyped declarations for all func- tions declared and/or defined in a translation unit, including those in header files. This option is silently ignored in any lan- guage other than C. Besides declarations, the file indicates, in comments, the origin of each declaration (source file and line), whether the declaration was implicit, prototyped or unprototyped (II, NN for new or OO for old, respectively, in the first character after the line number and the colon), and whether it came from a declaration or a definition (CC or FF, respectively, in the following character). In the case of function definitions, a K&R-style list of arguments followed by their declarations is also provided, inside comments, after the declaration. --ffaallllooww--ppaarraammeetteerrlleessss--vvaarriiaaddiicc--ffuunnccttiioonnss Accept variadic functions without named parameters. Although it is possible to define such a function, this is not very useful as it is not possible to read the arguments. This is only supported for C as this construct is allowed by C++. --ffnnoo--aassmm Do not recognize "asm", "inline" or "typeof" as a keyword, so that code can use these words as identifiers. You can use the keywords "__asm__", "__inline__" and "__typeof__" instead. In C, --aannssii im- plies --ffnnoo--aassmm. In C++, "inline" is a standard keyword and is not affected by this switch. You may want to use the --ffnnoo--ggnnuu--kkeeyywwoorrddss flag instead, which disables "typeof" but not "asm" and "inline". In C99 mode (--ssttdd==cc9999 or --ssttdd==ggnnuu9999), this switch only affects the "asm" and "typeof" keywords, since "inline" is a standard keyword in ISO C99. --ffnnoo--bbuuiillttiinn --ffnnoo--bbuuiillttiinn--_f_u_n_c_t_i_o_n Don't recognize built-in functions that do not begin with ____bbuuiillttiinn__ as prefix. GCC normally generates special code to handle certain built-in functions more efficiently; for instance, calls to "alloca" may be- come single instructions which adjust the stack directly, and calls to "memcpy" may become inline copy loops. The resulting code is often both smaller and faster, but since the function calls no longer appear as such, you cannot set a breakpoint on those calls, nor can you change the behavior of the functions by linking with a different library. In addition, when a function is recognized as a built-in function, GCC may use information about that function to warn about problems with calls to that function, or to generate more efficient code, even if the resulting code still contains calls to that function. For example, warnings are given with --WWffoorrmmaatt for bad calls to "printf" when "printf" is built in and "strlen" is known not to modify global memory. With the --ffnnoo--bbuuiillttiinn--_f_u_n_c_t_i_o_n option only the built-in function _f_u_n_c_t_i_o_n is disabled. _f_u_n_c_t_i_o_n must not begin with ____bbuuiillttiinn__. If a function is named that is not built-in in this version of GCC, this option is ignored. There is no corresponding --ffbbuuiillttiinn--_f_u_n_c_- _t_i_o_n option; if you wish to enable built-in functions selectively when using --ffnnoo--bbuuiillttiinn or --ffffrreeeessttaannddiinngg, you may define macros such as: #define abs(n) __builtin_abs ((n)) #define strcpy(d, s) __builtin_strcpy ((d), (s)) --ffccoonndd--mmiissmmaattcchh Allow conditional expressions with mismatched types in the second and third arguments. The value of such an expression is void. This option is not supported for C++. --ffffrreeeessttaannddiinngg Assert that compilation targets a freestanding environment. This implies --ffnnoo--bbuuiillttiinn. A freestanding environment is one in which the standard library may not exist, and program startup may not necessarily be at "main". The most obvious example is an OS ker- nel. This is equivalent to --ffnnoo--hhoosstteedd. --ffggiimmppllee Enable parsing of function definitions marked with "__GIMPLE". This is an experimental feature that allows unit testing of GIMPLE passes. --ffggnnuu--ttmm When the option --ffggnnuu--ttmm is specified, the compiler generates code for the Linux variant of Intel's current Transactional Memory ABI specification document (Revision 1.1, May 6 2009). This is an ex- perimental feature whose interface may change in future versions of GCC, as the official specification changes. Please note that not all architectures are supported for this feature. For more information on GCC's support for transactional memory, Note that the transactional memory feature is not supported with non-call exceptions (--ffnnoonn--ccaallll--eexxcceeppttiioonnss). --ffggnnuu8899--iinnlliinnee The option --ffggnnuu8899--iinnlliinnee tells GCC to use the traditional GNU se- mantics for "inline" functions when in C99 mode. Using this option is roughly equivalent to adding the "gnu_inline" function attribute to all inline functions. The option --ffnnoo--ggnnuu8899--iinnlliinnee explicitly tells GCC to use the C99 semantics for "inline" when in C99 or gnu99 mode (i.e., it speci- fies the default behavior). This option is not supported in --ssttdd==cc9900 or --ssttdd==ggnnuu9900 mode. The preprocessor macros "__GNUC_GNU_INLINE__" and "__GNUC_STDC_IN- LINE__" may be used to check which semantics are in effect for "in- line" functions. --ffhhoosstteedd Assert that compilation targets a hosted environment. This implies --ffbbuuiillttiinn. A hosted environment is one in which the entire stan- dard library is available, and in which "main" has a return type of "int". Examples are nearly everything except a kernel. This is equivalent to --ffnnoo--ffrreeeessttaannddiinngg. --ffllaaxx--vveeccttoorr--ccoonnvveerrssiioonnss Allow implicit conversions between vectors with differing numbers of elements and/or incompatible element types. This option should not be used for new code. --ffmmss--eexxtteennssiioonnss Accept some non-standard constructs used in Microsoft header files. In C++ code, this allows member names in structures to be similar to previous types declarations. typedef int UOW; struct ABC { UOW UOW; }; Some cases of unnamed fields in structures and unions are only ac- cepted with this option. Note that this option is off for all targets except for x86 targets using ms-abi. --ffooffffllooaadd==ddiissaabbllee --ffooffffllooaadd==ddeeffaauulltt --ffooffffllooaadd==_t_a_r_g_e_t_-_l_i_s_t Specify for which OpenMP and OpenACC offload targets code should be generated. The default behavior, equivalent to --ffooffffllooaadd==ddeeffaauulltt, is to generate code for all supported offload targets. The --ffooff-- ffllooaadd==ddiissaabbllee form generates code only for the host fallback, while --ffooffffllooaadd==_t_a_r_g_e_t_-_l_i_s_t generates code only for the specified comma- separated list of offload targets. Offload targets are specified in GCC's internal target-triplet for- mat. You can run the compiler with --vv to show the list of config- ured offload targets under "OFFLOAD_TARGET_NAMES". --ffooffffllooaadd--ooppttiioonnss==_o_p_t_i_o_n_s --ffooffffllooaadd--ooppttiioonnss==_t_a_r_g_e_t_-_t_r_i_p_l_e_t_-_l_i_s_t==_o_p_t_i_o_n_s With --ffooffffllooaadd--ooppttiioonnss==_o_p_t_i_o_n_s, GCC passes the specified _o_p_t_i_o_n_s to the compilers for all enabled offloading targets. You can specify options that apply only to a specific target or targets by using the --ffooffffllooaadd--ooppttiioonnss==_t_a_r_g_e_t_-_l_i_s_t==_o_p_t_i_o_n_s form. The _t_a_r_g_e_t_-_l_i_s_t is a comma-separated list in the same format as for the --ffooffffllooaadd== op- tion. Typical command lines are -foffload-options=-lgfortran -foffload-options=-lm -foffload-options="-lgfortran -lm" -foffload-options=nvptx-none=-latomic -foffload-options=amdgcn-amdhsa=-march=gfx906 -foffload-options=-lm --ffooppeennaacccc Enable handling of OpenACC directives "#pragma acc" in C/C++ and "!$acc" in Fortran. When --ffooppeennaacccc is specified, the compiler gen- erates accelerated code according to the OpenACC Application Pro- gramming Interface v2.6 . This option im- plies --pptthhrreeaadd, and thus is only supported on targets that have support for --pptthhrreeaadd. --ffooppeennaacccc--ddiimm==_g_e_o_m Specify default compute dimensions for parallel offload regions that do not explicitly specify. The _g_e_o_m value is a triple of ':'-separated sizes, in order 'gang', 'worker' and, 'vector'. A size can be omitted, to use a target-specific default value. --ffooppeennmmpp Enable handling of OpenMP directives "#pragma omp" in C/C++ and "!$omp" in Fortran. When --ffooppeennmmpp is specified, the compiler gen- erates parallel code according to the OpenMP Application Program Interface v4.5 . This option implies --pptthhrreeaadd, and thus is only supported on targets that have support for --pptthhrreeaadd. --ffooppeennmmpp implies --ffooppeennmmpp--ssiimmdd. --ffooppeennmmpp--ssiimmdd Enable handling of OpenMP's SIMD directives with "#pragma omp" in C/C++ and "!$omp" in Fortran. Other OpenMP directives are ignored. --ffppeerrmmiitttteedd--fflltt--eevvaall--mmeetthhooddss==_s_t_y_l_e ISO/IEC TS 18661-3 defines new permissible values for "FLT_EVAL_METHOD" that indicate that operations and constants with a semantic type that is an interchange or extended format should be evaluated to the precision and range of that type. These new val- ues are a superset of those permitted under C99/C11, which does not specify the meaning of other positive values of "FLT_EVAL_METHOD". As such, code conforming to C11 may not have been written expecting the possibility of the new values. --ffppeerrmmiitttteedd--fflltt--eevvaall--mmeetthhooddss specifies whether the compiler should allow only the values of "FLT_EVAL_METHOD" specified in C99/C11, or the extended set of values specified in ISO/IEC TS 18661-3. _s_t_y_l_e is either "c11" or "ts-18661-3" as appropriate. The default when in a standards compliant mode (--ssttdd==cc1111 or simi- lar) is --ffppeerrmmiitttteedd--fflltt--eevvaall--mmeetthhooddss==cc1111. The default when in a GNU dialect (--ssttdd==ggnnuu1111 or similar) is --ffppeerrmmiitttteedd--fflltt--eevvaall--mmeetthh-- ooddss==ttss--1188666611--33. --ffppllaann99--eexxtteennssiioonnss Accept some non-standard constructs used in Plan 9 code. This enables --ffmmss--eexxtteennssiioonnss, permits passing pointers to struc- tures with anonymous fields to functions that expect pointers to elements of the type of the field, and permits referring to anony- mous fields declared using a typedef. This is only supported for C, not C++. --ffssiiggnneedd--bbiittffiieellddss --ffuunnssiiggnneedd--bbiittffiieellddss --ffnnoo--ssiiggnneedd--bbiittffiieellddss --ffnnoo--uunnssiiggnneedd--bbiittffiieellddss These options control whether a bit-field is signed or unsigned, when the declaration does not use either "signed" or "unsigned". By default, such a bit-field is signed, because this is consistent: the basic integer types such as "int" are signed types. --ffssiiggnneedd--cchhaarr Let the type "char" be signed, like "signed char". Note that this is equivalent to --ffnnoo--uunnssiiggnneedd--cchhaarr, which is the negative form of --ffuunnssiiggnneedd--cchhaarr. Likewise, the option --ffnnoo--ssiiggnneedd--cchhaarr is equivalent to --ffuunnssiiggnneedd--cchhaarr. --ffuunnssiiggnneedd--cchhaarr Let the type "char" be unsigned, like "unsigned char". Each kind of machine has a default for what "char" should be. It is either like "unsigned char" by default or like "signed char" by default. Ideally, a portable program should always use "signed char" or "un- signed char" when it depends on the signedness of an object. But many programs have been written to use plain "char" and expect it to be signed, or expect it to be unsigned, depending on the ma- chines they were written for. This option, and its inverse, let you make such a program work with the opposite default. The type "char" is always a distinct type from each of "signed char" or "unsigned char", even though its behavior is always just like one of those two. --ffssssoo--ssttrruucctt==_e_n_d_i_a_n_n_e_s_s Set the default scalar storage order of structures and unions to the specified endianness. The accepted values are bbiigg--eennddiiaann, lliitt-- ttllee--eennddiiaann and nnaattiivvee for the native endianness of the target (the default). This option is not supported for C++. WWaarrnniinngg:: the --ffssssoo--ssttrruucctt switch causes GCC to generate code that is not binary compatible with code generated without it if the specified endianness is not the native endianness of the target. OOppttiioonnss CCoonnttrroolllliinngg CC++++ DDiiaalleecctt This section describes the command-line options that are only meaning- ful for C++ programs. You can also use most of the GNU compiler op- tions regardless of what language your program is in. For example, you might compile a file _f_i_r_s_t_C_l_a_s_s_._C like this: g++ -g -fstrict-enums -O -c firstClass.C In this example, only --ffssttrriicctt--eennuummss is an option meant only for C++ programs; you can use the other options with any language supported by GCC. Some options for compiling C programs, such as --ssttdd, are also relevant for C++ programs. Here is a list of options that are _o_n_l_y for compiling C++ programs: --ffaabbii--vveerrssiioonn==_n Use version _n of the C++ ABI. The default is version 0. Version 0 refers to the version conforming most closely to the C++ ABI specification. Therefore, the ABI obtained using version 0 will change in different versions of G++ as ABI bugs are fixed. Version 1 is the version of the C++ ABI that first appeared in G++ 3.2. Version 2 is the version of the C++ ABI that first appeared in G++ 3.4, and was the default through G++ 4.9. Version 3 corrects an error in mangling a constant address as a template argument. Version 4, which first appeared in G++ 4.5, implements a standard mangling for vector types. Version 5, which first appeared in G++ 4.6, corrects the mangling of attribute const/volatile on function pointer types, decltype of a plain decl, and use of a function parameter in the declaration of another parameter. Version 6, which first appeared in G++ 4.7, corrects the promotion behavior of C++11 scoped enums and the mangling of template argu- ment packs, const/static_cast, prefix ++ and --, and a class scope function used as a template argument. Version 7, which first appeared in G++ 4.8, that treats nullptr_t as a builtin type and corrects the mangling of lambdas in default argument scope. Version 8, which first appeared in G++ 4.9, corrects the substitu- tion behavior of function types with function-cv-qualifiers. Version 9, which first appeared in G++ 5.2, corrects the alignment of "nullptr_t". Version 10, which first appeared in G++ 6.1, adds mangling of at- tributes that affect type identity, such as ia32 calling convention attributes (e.g. ssttddccaallll). Version 11, which first appeared in G++ 7, corrects the mangling of sizeof... expressions and operator names. For multiple entities with the same name within a function, that are declared in differ- ent scopes, the mangling now changes starting with the twelfth oc- currence. It also implies --ffnneeww--iinnhheerriittiinngg--ccttoorrss. Version 12, which first appeared in G++ 8, corrects the calling conventions for empty classes on the x86_64 target and for classes with only deleted copy/move constructors. It accidentally changes the calling convention for classes with a deleted copy constructor and a trivial move constructor. Version 13, which first appeared in G++ 8.2, fixes the accidental change in version 12. Version 14, which first appeared in G++ 10, corrects the mangling of the nullptr expression. Version 15, which first appeared in G++ 11, changes the mangling of "__alignof__" to be distinct from that of "alignof", and dependent operator names. See also --WWaabbii. --ffaabbii--ccoommppaatt--vveerrssiioonn==_n On targets that support strong aliases, G++ works around mangling changes by creating an alias with the correct mangled name when defining a symbol with an incorrect mangled name. This switch specifies which ABI version to use for the alias. With --ffaabbii--vveerrssiioonn==00 (the default), this defaults to 11 (GCC 7 com- patibility). If another ABI version is explicitly selected, this defaults to 0. For compatibility with GCC versions 3.2 through 4.9, use --ffaabbii--ccoommppaatt--vveerrssiioonn==22. If this option is not provided but --WWaabbii==_n is, that version is used for compatibility aliases. If this option is provided along with --WWaabbii (without the version), the version from this option is used for the warning. --ffnnoo--aacccceessss--ccoonnttrrooll Turn off all access checking. This switch is mainly useful for working around bugs in the access control code. --ffaalliiggnneedd--nneeww Enable support for C++17 "new" of types that require more alignment than "void* ::operator new(std::size_t)" provides. A numeric argu- ment such as "-faligned-new=32" can be used to specify how much alignment (in bytes) is provided by that function, but few users will need to override the default of "alignof(std::max_align_t)". This flag is enabled by default for --ssttdd==cc++++1177. --ffcchhaarr88__tt --ffnnoo--cchhaarr88__tt Enable support for "char8_t" as adopted for C++20. This includes the addition of a new "char8_t" fundamental type, changes to the types of UTF-8 string and character literals, new signatures for user-defined literals, associated standard library updates, and new "__cpp_char8_t" and "__cpp_lib_char8_t" feature test macros. This option enables functions to be overloaded for ordinary and UTF-8 strings: int f(const char *); // #1 int f(const char8_t *); // #2 int v1 = f("text"); // Calls #1 int v2 = f(u8"text"); // Calls #2 and introduces new signatures for user-defined literals: int operator""_udl1(char8_t); int v3 = u8'x'_udl1; int operator""_udl2(const char8_t*, std::size_t); int v4 = u8"text"_udl2; template int operator""_udl3(); int v5 = u8"text"_udl3; The change to the types of UTF-8 string and character literals in- troduces incompatibilities with ISO C++11 and later standards. For example, the following code is well-formed under ISO C++11, but is ill-formed when --ffcchhaarr88__tt is specified. char ca[] = u8"xx"; // error: char-array initialized from wide // string const char *cp = u8"xx";// error: invalid conversion from // `const char8_t*' to `const char*' int f(const char*); auto v = f(u8"xx"); // error: invalid conversion from // `const char8_t*' to `const char*' std::string s{u8"xx"}; // error: no matching function for call to // `std::basic_string::basic_string()' using namespace std::literals; s = u8"xx"s; // error: conversion from // `basic_string' to non-scalar // type `basic_string' requested --ffcchheecckk--nneeww Check that the pointer returned by "operator new" is non-null be- fore attempting to modify the storage allocated. This check is normally unnecessary because the C++ standard specifies that "oper- ator new" only returns 0 if it is declared "throw()", in which case the compiler always checks the return value even without this op- tion. In all other cases, when "operator new" has a non-empty ex- ception specification, memory exhaustion is signalled by throwing "std::bad_alloc". See also nneeww ((nnootthhrrooww)). --ffccoonncceeppttss --ffccoonncceeppttss--ttss Below --ssttdd==cc++++2200, --ffccoonncceeppttss enables support for the C++ Extensions for Concepts Technical Specification, ISO 19217 (2015). With --ssttdd==cc++++2200 and above, Concepts are part of the language stan- dard, so --ffccoonncceeppttss defaults to on. But the standard specification of Concepts differs significantly from the TS, so some constructs that were allowed in the TS but didn't make it into the standard can still be enabled by --ffccoonncceeppttss--ttss. --ffccoonnsstteexxpprr--ddeepptthh==_n Set the maximum nested evaluation depth for C++11 constexpr func- tions to _n. A limit is needed to detect endless recursion during constant expression evaluation. The minimum specified by the stan- dard is 512. --ffccoonnsstteexxpprr--ccaacchhee--ddeepptthh==_n Set the maximum level of nested evaluation depth for C++11 const- expr functions that will be cached to _n. This is a heuristic that trades off compilation speed (when the cache avoids repeated calcu- lations) against memory consumption (when the cache grows very large from highly recursive evaluations). The default is 8. Very few users are likely to want to adjust it, but if your code does heavy constexpr calculations you might want to experiment to find which value works best for you. --ffccoonnsstteexxpprr--ffpp--eexxcceepptt Annex F of the C standard specifies that IEC559 floating point ex- ceptions encountered at compile time should not stop compilation. C++ compilers have historically not followed this guidance, instead treating floating point division by zero as non-constant even though it has a well defined value. This flag tells the compiler to give Annex F priority over other rules saying that a particular operation is undefined. constexpr float inf = 1./0.; // OK with -fconstexpr-fp-except --ffccoonnsstteexxpprr--lloooopp--lliimmiitt==_n Set the maximum number of iterations for a loop in C++14 constexpr functions to _n. A limit is needed to detect infinite loops during constant expression evaluation. The default is 262144 (1<<18). --ffccoonnsstteexxpprr--ooppss--lliimmiitt==_n Set the maximum number of operations during a single constexpr evaluation. Even when number of iterations of a single loop is limited with the above limit, if there are several nested loops and each of them has many iterations but still smaller than the above limit, or if in a body of some loop or even outside of a loop too many expressions need to be evaluated, the resulting constexpr evaluation might take too long. The default is 33554432 (1<<25). --ffccoorroouuttiinneess Enable support for the C++ coroutines extension (experimental). --ffnnoo--eelliiddee--ccoonnssttrruuccttoorrss The C++ standard allows an implementation to omit creating a tempo- rary that is only used to initialize another object of the same type. Specifying this option disables that optimization, and forces G++ to call the copy constructor in all cases. This option also causes G++ to call trivial member functions which otherwise would be expanded inline. In C++17, the compiler is required to omit these temporaries, but this option still affects trivial member functions. --ffnnoo--eennffoorrccee--eehh--ssppeeccss Don't generate code to check for violation of exception specifica- tions at run time. This option violates the C++ standard, but may be useful for reducing code size in production builds, much like defining "NDEBUG". This does not give user code permission to throw exceptions in violation of the exception specifications; the compiler still optimizes based on the specifications, so throwing an unexpected exception results in undefined behavior at run time. --ffeexxtteerrnn--ttllss--iinniitt --ffnnoo--eexxtteerrnn--ttllss--iinniitt The C++11 and OpenMP standards allow "thread_local" and "threadpri- vate" variables to have dynamic (runtime) initialization. To sup- port this, any use of such a variable goes through a wrapper func- tion that performs any necessary initialization. When the use and definition of the variable are in the same translation unit, this overhead can be optimized away, but when the use is in a different translation unit there is significant overhead even if the variable doesn't actually need dynamic initialization. If the programmer can be sure that no use of the variable in a non-defining TU needs to trigger dynamic initialization (either because the variable is statically initialized, or a use of the variable in the defining TU will be executed before any uses in another TU), they can avoid this overhead with the --ffnnoo--eexxtteerrnn--ttllss--iinniitt option. On targets that support symbol aliases, the default is --ffeexx-- tteerrnn--ttllss--iinniitt. On targets that do not support symbol aliases, the default is --ffnnoo--eexxtteerrnn--ttllss--iinniitt. --ffffoolldd--ssiimmppllee--iinnlliinneess --ffnnoo--ffoolldd--ssiimmppllee--iinnlliinneess Permit the C++ frontend to fold calls to "std::move", "std::for- ward", "std::addressof" and "std::as_const". In contrast to inlin- ing, this means no debug information will be generated for such calls. Since these functions are rarely interesting to debug, this flag is enabled by default unless --ffnnoo--iinnlliinnee is active. --ffnnoo--ggnnuu--kkeeyywwoorrddss Do not recognize "typeof" as a keyword, so that code can use this word as an identifier. You can use the keyword "__typeof__" in- stead. This option is implied by the strict ISO C++ dialects: --aannssii, --ssttdd==cc++++9988, --ssttdd==cc++++1111, etc. --ffiimmpplliicciitt--ccoonnsstteexxpprr Make inline functions implicitly constexpr, if they satisfy the re- quirements for a constexpr function. This option can be used in C++14 mode or later. This can result in initialization changing from dynamic to static and other optimizations. --ffnnoo--iimmpplliicciitt--tteemmppllaatteess Never emit code for non-inline templates that are instantiated im- plicitly (i.e. by use); only emit code for explicit instantiations. If you use this option, you must take care to structure your code to include all the necessary explicit instantiations to avoid get- ting undefined symbols at link time. --ffnnoo--iimmpplliicciitt--iinnlliinnee--tteemmppllaatteess Don't emit code for implicit instantiations of inline templates, either. The default is to handle inlines differently so that com- piles with and without optimization need the same set of explicit instantiations. --ffnnoo--iimmpplleemmeenntt--iinnlliinneess To save space, do not emit out-of-line copies of inline functions controlled by "#pragma implementation". This causes linker errors if these functions are not inlined everywhere they are called. --ffmmoodduulleess--ttss --ffnnoo--mmoodduulleess--ttss Enable support for C++20 modules. The --ffnnoo--mmoodduulleess--ttss is usually not needed, as that is the default. Even though this is a C++20 feature, it is not currently implicitly enabled by selecting that standard version. --ffmmoodduullee--hheeaaddeerr --ffmmoodduullee--hheeaaddeerr==uusseerr --ffmmoodduullee--hheeaaddeerr==ssyysstteemm Compile a header file to create an importable header unit. --ffmmoodduullee--iimmpplliicciitt--iinnlliinnee Member functions defined in their class definitions are not implic- itly inline for modular code. This is different to traditional C++ behavior, for good reasons. However, it may result in a difficulty during code porting. This option makes such function definitions implicitly inline. It does however generate an ABI incompatibil- ity, so you must use it everywhere or nowhere. (Such definitions outside of a named module remain implicitly inline, regardless.) --ffnnoo--mmoodduullee--llaazzyy Disable lazy module importing and module mapper creation. --ffmmoodduullee--mmaappppeerr==[_h_o_s_t_n_a_m_e]::_p_o_r_t[??_i_d_e_n_t] --ffmmoodduullee--mmaappppeerr==||_p_r_o_g_r_a_m[??_i_d_e_n_t] _a_r_g_s_._._. --ffmmoodduullee--mmaappppeerr====_s_o_c_k_e_t[??_i_d_e_n_t] --ffmmoodduullee--mmaappppeerr==<<>>[_i_n_o_u_t][??_i_d_e_n_t] --ffmmoodduullee--mmaappppeerr==<<_i_n>>_o_u_t[??_i_d_e_n_t] --ffmmoodduullee--mmaappppeerr==_f_i_l_e[??_i_d_e_n_t] An oracle to query for module name to filename mappings. If un- specified the CCXXXX__MMOODDUULLEE__MMAAPPPPEERR environment variable is used, and if that is unset, an in-process default is provided. --ffmmoodduullee--oonnllyy Only emit the Compiled Module Interface, inhibiting any object file. --ffmmss--eexxtteennssiioonnss Disable Wpedantic warnings about constructs used in MFC, such as implicit int and getting a pointer to member function via non-stan- dard syntax. --ffnneeww--iinnhheerriittiinngg--ccttoorrss Enable the P0136 adjustment to the semantics of C++11 constructor inheritance. This is part of C++17 but also considered to be a De- fect Report against C++11 and C++14. This flag is enabled by de- fault unless --ffaabbii--vveerrssiioonn==1100 or lower is specified. --ffnneeww--ttttpp--mmaattcchhiinngg Enable the P0522 resolution to Core issue 150, template template parameters and default arguments: this allows a template with de- fault template arguments as an argument for a template template pa- rameter with fewer template parameters. This flag is enabled by default for --ssttdd==cc++++1177. --ffnnoo--nnoonnaannssii--bbuuiillttiinnss Disable built-in declarations of functions that are not mandated by ANSI/ISO C. These include "ffs", "alloca", "_exit", "index", "bzero", "conjf", and other related functions. --ffnnootthhrrooww--oopptt Treat a "throw()" exception specification as if it were a "noex- cept" specification to reduce or eliminate the text size overhead relative to a function with no exception specification. If the function has local variables of types with non-trivial destructors, the exception specification actually makes the function smaller be- cause the EH cleanups for those variables can be optimized away. The semantic effect is that an exception thrown out of a function with such an exception specification results in a call to "termi- nate" rather than "unexpected". --ffnnoo--ooppeerraattoorr--nnaammeess Do not treat the operator name keywords "and", "bitand", "bitor", "compl", "not", "or" and "xor" as synonyms as keywords. --ffnnoo--ooppttiioonnaall--ddiiaaggss Disable diagnostics that the standard says a compiler does not need to issue. Currently, the only such diagnostic issued by G++ is the one for a name having multiple meanings within a class. --ffppeerrmmiissssiivvee Downgrade some diagnostics about nonconformant code from errors to warnings. Thus, using --ffppeerrmmiissssiivvee allows some nonconforming code to compile. --ffnnoo--pprreettttyy--tteemmppllaatteess When an error message refers to a specialization of a function tem- plate, the compiler normally prints the signature of the template followed by the template arguments and any typedefs or typenames in the signature (e.g. "void f(T) [with T = int]" rather than "void f(int)") so that it's clear which template is involved. When an error message refers to a specialization of a class template, the compiler omits any template arguments that match the default tem- plate arguments for that template. If either of these behaviors make it harder to understand the error message rather than easier, you can use --ffnnoo--pprreettttyy--tteemmppllaatteess to disable them. --ffnnoo--rrttttii Disable generation of information about every class with virtual functions for use by the C++ run-time type identification features ("dynamic_cast" and "typeid"). If you don't use those parts of the language, you can save some space by using this flag. Note that exception handling uses the same information, but G++ generates it as needed. The "dynamic_cast" operator can still be used for casts that do not require run-time type information, i.e. casts to "void *" or to unambiguous base classes. Mixing code compiled with --ffrrttttii with that compiled with --ffnnoo--rrttttii may not work. For example, programs may fail to link if a class compiled with --ffnnoo--rrttttii is used as a base for a class compiled with --ffrrttttii. --ffssiizzeedd--ddeeaallllooccaattiioonn Enable the built-in global declarations void operator delete (void *, std::size_t) noexcept; void operator delete[] (void *, std::size_t) noexcept; as introduced in C++14. This is useful for user-defined replace- ment deallocation functions that, for example, use the size of the object to make deallocation faster. Enabled by default under --ssttdd==cc++++1144 and above. The flag --WWssiizzeedd--ddeeaallllooccaattiioonn warns about places that might want to add a definition. --ffssttrriicctt--eennuummss Allow the compiler to optimize using the assumption that a value of enumerated type can only be one of the values of the enumeration (as defined in the C++ standard; basically, a value that can be represented in the minimum number of bits needed to represent all the enumerators). This assumption may not be valid if the program uses a cast to convert an arbitrary integer value to the enumerated type. --ffssttrroonngg--eevvaall--oorrddeerr Evaluate member access, array subscripting, and shift expressions in left-to-right order, and evaluate assignment in right-to-left order, as adopted for C++17. Enabled by default with --ssttdd==cc++++1177. --ffssttrroonngg--eevvaall--oorrddeerr==ssoommee enables just the ordering of member access and shift expressions, and is the default without --ssttdd==cc++++1177. --fftteemmppllaattee--bbaacckkttrraaccee--lliimmiitt==_n Set the maximum number of template instantiation notes for a single warning or error to _n. The default value is 10. --fftteemmppllaattee--ddeepptthh==_n Set the maximum instantiation depth for template classes to _n. A limit on the template instantiation depth is needed to detect end- less recursions during template class instantiation. ANSI/ISO C++ conforming programs must not rely on a maximum depth greater than 17 (changed to 1024 in C++11). The default value is 900, as the compiler can run out of stack space before hitting 1024 in some situations. --ffnnoo--tthhrreeaaddssaaffee--ssttaattiiccss Do not emit the extra code to use the routines specified in the C++ ABI for thread-safe initialization of local statics. You can use this option to reduce code size slightly in code that doesn't need to be thread-safe. --ffuussee--ccxxaa--aatteexxiitt Register destructors for objects with static storage duration with the "__cxa_atexit" function rather than the "atexit" function. This option is required for fully standards-compliant handling of static destructors, but only works if your C library supports "__cxa_atexit". --ffnnoo--uussee--ccxxaa--ggeett--eexxcceeppttiioonn--ppttrr Don't use the "__cxa_get_exception_ptr" runtime routine. This causes "std::uncaught_exception" to be incorrect, but is necessary if the runtime routine is not available. --ffvviissiibbiilliittyy--iinnlliinneess--hhiiddddeenn This switch declares that the user does not attempt to compare pointers to inline functions or methods where the addresses of the two functions are taken in different shared objects. The effect of this is that GCC may, effectively, mark inline meth- ods with "__attribute__ ((visibility ("hidden")))" so that they do not appear in the export table of a DSO and do not require a PLT indirection when used within the DSO. Enabling this option can have a dramatic effect on load and link times of a DSO as it mas- sively reduces the size of the dynamic export table when the li- brary makes heavy use of templates. The behavior of this switch is not quite the same as marking the methods as hidden directly, because it does not affect static vari- ables local to the function or cause the compiler to deduce that the function is defined in only one shared object. You may mark a method as having a visibility explicitly to negate the effect of the switch for that method. For example, if you do want to compare pointers to a particular inline method, you might mark it as having default visibility. Marking the enclosing class with explicit visibility has no effect. Explicitly instantiated inline methods are unaffected by this op- tion as their linkage might otherwise cross a shared library bound- ary. --ffvviissiibbiilliittyy--mmss--ccoommppaatt This flag attempts to use visibility settings to make GCC's C++ linkage model compatible with that of Microsoft Visual Studio. The flag makes these changes to GCC's linkage model: 1. It sets the default visibility to "hidden", like --ffvviissiibbiill-- iittyy==hhiiddddeenn. 2. Types, but not their members, are not hidden by default. 3. The One Definition Rule is relaxed for types without explicit visibility specifications that are defined in more than one shared object: those declarations are permitted if they are permitted when this option is not used. In new code it is better to use --ffvviissiibbiilliittyy==hhiiddddeenn and export those classes that are intended to be externally visible. Unfortu- nately it is possible for code to rely, perhaps accidentally, on the Visual Studio behavior. Among the consequences of these changes are that static data mem- bers of the same type with the same name but defined in different shared objects are different, so changing one does not change the other; and that pointers to function members defined in different shared objects may not compare equal. When this flag is given, it is a violation of the ODR to define types with the same name dif- ferently. --ffnnoo--wweeaakk Do not use weak symbol support, even if it is provided by the linker. By default, G++ uses weak symbols if they are available. This option exists only for testing, and should not be used by end-users; it results in inferior code and has no benefits. This option may be removed in a future release of G++. --ffeexxtt--nnuummeerriicc--lliitteerraallss (C++ and Objective-C++ only) Accept imaginary, fixed-point, or machine-defined literal number suffixes as GNU extensions. When this option is turned off these suffixes are treated as C++11 user-defined literal numeric suf- fixes. This is on by default for all pre-C++11 dialects and all GNU dialects: --ssttdd==cc++++9988, --ssttdd==ggnnuu++++9988, --ssttdd==ggnnuu++++1111, --ssttdd==ggnnuu++++1144. This option is off by default for ISO C++11 onwards (--ssttdd==cc++++1111, ...). --nnoossttddiinncc++++ Do not search for header files in the standard directories specific to C++, but do still search the other standard directories. (This option is used when building the C++ library.) --ffllaanngg--iinnffoo--iinncclluuddee--ttrraannssllaattee --ffllaanngg--iinnffoo--iinncclluuddee--ttrraannssllaattee--nnoott --ffllaanngg--iinnffoo--iinncclluuddee--ttrraannssllaattee==_h_e_a_d_e_r Inform of include translation events. The first will note accepted include translations, the second will note declined include trans- lations. The _h_e_a_d_e_r form will inform of include translations re- lating to that specific header. If _h_e_a_d_e_r is of the form "user" or "" it will be resolved to a specific user or system header using the include path. --ffllaanngg--iinnffoo--mmoodduullee--ccmmii --ffllaanngg--iinnffoo--mmoodduullee--ccmmii==_m_o_d_u_l_e Inform of Compiled Module Interface pathnames. The first will note all read CMI pathnames. The _m_o_d_u_l_e form will not reading a spe- cific module's CMI. _m_o_d_u_l_e may be a named module or a header-unit (the latter indicated by either being a pathname containing direc- tory separators or enclosed in "<>" or ""). --ssttddlliibb==_l_i_b_s_t_d_c_+_+_,_l_i_b_c_+_+ When G++ is configured to support this option, it allows specifica- tion of alternate C++ runtime libraries. Two options are avail- able: _l_i_b_s_t_d_c_+_+ (the default, native C++ runtime for G++) and _l_i_b_c_+_+ which is the C++ runtime installed on some operating systems (e.g. Darwin versions from Darwin11 onwards). The option switches G++ to use the headers from the specified library and to emit "-lstdc++" or "-lc++" respectively, when a C++ runtime is required for linking. In addition, these warning options have meanings only for C++ programs: --WWaabbii--ttaagg (C++ and Objective-C++ only) Warn when a type with an ABI tag is used in a context that does not have that ABI tag. See CC++++ AAttttrriibbuutteess for more information about ABI tags. --WWccoommmmaa--ssuubbssccrriipptt (C++ and Objective-C++ only) Warn about uses of a comma expression within a subscripting expres- sion. This usage was deprecated in C++20 and is going to be re- moved in C++23. However, a comma expression wrapped in "( )" is not deprecated. Example: void f(int *a, int b, int c) { a[b,c]; // deprecated in C++20, invalid in C++23 a[(b,c)]; // OK } In C++23 it is valid to have comma separated expressions in a sub- script when an overloaded subscript operator is found and supports the right number and types of arguments. G++ will accept the for- merly valid syntax for code that is not valid in C++23 but used to be valid but deprecated in C++20 with a pedantic warning that can be disabled with --WWnnoo--ccoommmmaa--ssuubbssccrriipptt. Enabled by default with --ssttdd==cc++++2200 unless --WWnnoo--ddeepprreeccaatteedd, and with --ssttdd==cc++++2233 regardless of --WWnnoo--ddeepprreeccaatteedd. --WWccttaadd--mmaayybbee--uunnssuuppppoorrtteedd (C++ and Objective-C++ only) Warn when performing class template argument deduction (CTAD) on a type with no explicitly written deduction guides. This warning will point out cases where CTAD succeeded only because the compiler synthesized the implicit deduction guides, which might not be what the programmer intended. Certain style guides allow CTAD only on types that specifically "opt-in"; i.e., on types that are designed to support CTAD. This warning can be suppressed with the following pattern: struct allow_ctad_t; // any name works template struct S { S(T) { } }; S(allow_ctad_t) -> S; // guide with incomplete parameter type will never be considered --WWccttoorr--ddttoorr--pprriivvaaccyy (C++ and Objective-C++ only) Warn when a class seems unusable because all the constructors or destructors in that class are private, and it has neither friends nor public static member functions. Also warn if there are no non- private methods, and there's at least one private member function that isn't a constructor or destructor. --WWddeelleettee--nnoonn--vviirrttuuaall--ddttoorr (C++ and Objective-C++ only) Warn when "delete" is used to destroy an instance of a class that has virtual functions and non-virtual destructor. It is unsafe to delete an instance of a derived class through a pointer to a base class if the base class does not have a virtual destructor. This warning is enabled by --WWaallll. --WWddeepprreeccaatteedd--ccooppyy (C++ and Objective-C++ only) Warn that the implicit declaration of a copy constructor or copy assignment operator is deprecated if the class has a user-provided copy constructor or copy assignment operator, in C++11 and up. This warning is enabled by --WWeexxttrraa. With --WWddeepprreeccaatteedd--ccooppyy--ddttoorr, also deprecate if the class has a user-provided destructor. --WWnnoo--ddeepprreeccaatteedd--eennuumm--eennuumm--ccoonnvveerrssiioonn (C++ and Objective-C++ only) Disable the warning about the case when the usual arithmetic con- versions are applied on operands where one is of enumeration type and the other is of a different enumeration type. This conversion was deprecated in C++20. For example: enum E1 { e }; enum E2 { f }; int k = f - e; --WWddeepprreeccaatteedd--eennuumm--eennuumm--ccoonnvveerrssiioonn is enabled by default with --ssttdd==cc++++2200. In pre-C++20 dialects, this warning can be enabled by --WWeennuumm--ccoonnvveerrssiioonn. --WWnnoo--ddeepprreeccaatteedd--eennuumm--ffllooaatt--ccoonnvveerrssiioonn (C++ and Objective-C++ only) Disable the warning about the case when the usual arithmetic con- versions are applied on operands where one is of enumeration type and the other is of a floating-point type. This conversion was deprecated in C++20. For example: enum E1 { e }; enum E2 { f }; bool b = e <= 3.7; --WWddeepprreeccaatteedd--eennuumm--ffllooaatt--ccoonnvveerrssiioonn is enabled by default with --ssttdd==cc++++2200. In pre-C++20 dialects, this warning can be enabled by --WWeennuumm--ccoonnvveerrssiioonn. --WWnnoo--iinniitt--lliisstt--lliiffeettiimmee (C++ and Objective-C++ only) Do not warn about uses of "std::initializer_list" that are likely to result in dangling pointers. Since the underlying array for an "initializer_list" is handled like a normal C++ temporary object, it is easy to inadvertently keep a pointer to the array past the end of the array's lifetime. For example: * If a function returns a temporary "initializer_list", or a lo- cal "initializer_list" variable, the array's lifetime ends at the end of the return statement, so the value returned has a dangling pointer. * If a new-expression creates an "initializer_list", the array only lives until the end of the enclosing full-expression, so the "initializer_list" in the heap has a dangling pointer. * When an "initializer_list" variable is assigned from a brace- enclosed initializer list, the temporary array created for the right side of the assignment only lives until the end of the full-expression, so at the next statement the "initial- izer_list" variable has a dangling pointer. // li's initial underlying array lives as long as li std::initializer_list li = { 1,2,3 }; // assignment changes li to point to a temporary array li = { 4, 5 }; // now the temporary is gone and li has a dangling pointer int i = li.begin()[0] // undefined behavior * When a list constructor stores the "begin" pointer from the "initializer_list" argument, this doesn't extend the lifetime of the array, so if a class variable is constructed from a tem- porary "initializer_list", the pointer is left dangling by the end of the variable declaration statement. --WWiinnvvaalliidd--iimmppoorrtteedd--mmaaccrrooss Verify all imported macro definitions are valid at the end of com- pilation. This is not enabled by default, as it requires addi- tional processing to determine. It may be useful when preparing sets of header-units to ensure consistent macros. --WWnnoo--lliitteerraall--ssuuffffiixx (C++ and Objective-C++ only) Do not warn when a string or character literal is followed by a ud- suffix which does not begin with an underscore. As a conforming extension, GCC treats such suffixes as separate preprocessing to- kens in order to maintain backwards compatibility with code that uses formatting macros from "". For example: #define __STDC_FORMAT_MACROS #include #include int main() { int64_t i64 = 123; printf("My int64: %" PRId64"\n", i64); } In this case, "PRId64" is treated as a separate preprocessing to- ken. This option also controls warnings when a user-defined literal op- erator is declared with a literal suffix identifier that doesn't begin with an underscore. Literal suffix identifiers that don't be- gin with an underscore are reserved for future standardization. These warnings are enabled by default. --WWnnoo--nnaarrrroowwiinngg (C++ and Objective-C++ only) For C++11 and later standards, narrowing conversions are diagnosed by default, as required by the standard. A narrowing conversion from a constant produces an error, and a narrowing conversion from a non-constant produces a warning, but --WWnnoo--nnaarrrroowwiinngg suppresses the diagnostic. Note that this does not affect the meaning of well-formed code; narrowing conversions are still considered ill- formed in SFINAE contexts. With --WWnnaarrrroowwiinngg in C++98, warn when a narrowing conversion prohib- ited by C++11 occurs within {{ }}, e.g. int i = { 2.2 }; // error: narrowing from double to int This flag is included in --WWaallll and --WWcc++++1111--ccoommppaatt. --WWnnooeexxcceepptt (C++ and Objective-C++ only) Warn when a noexcept-expression evaluates to false because of a call to a function that does not have a non-throwing exception specification (i.e. "throw()" or "noexcept") but is known by the compiler to never throw an exception. --WWnnooeexxcceepptt--ttyyppee (C++ and Objective-C++ only) Warn if the C++17 feature making "noexcept" part of a function type changes the mangled name of a symbol relative to C++14. Enabled by --WWaabbii and --WWcc++++1177--ccoommppaatt. As an example: template void f(T t) { t(); }; void g() noexcept; void h() { f(g); } In C++14, "f" calls "f", but in C++17 it calls "f". --WWccllaassss--mmeemmaacccceessss (C++ and Objective-C++ only) Warn when the destination of a call to a raw memory function such as "memset" or "memcpy" is an object of class type, and when writ- ing into such an object might bypass the class non-trivial or deleted constructor or copy assignment, violate const-correctness or encapsulation, or corrupt virtual table pointers. Modifying the representation of such objects may violate invariants maintained by member functions of the class. For example, the call to "memset" below is undefined because it modifies a non-trivial class object and is, therefore, diagnosed. The safe way to either initialize or clear the storage of objects of such types is by using the appro- priate constructor or assignment operator, if one is available. std::string str = "abc"; memset (&str, 0, sizeof str); The --WWccllaassss--mmeemmaacccceessss option is enabled by --WWaallll. Explicitly cast- ing the pointer to the class object to "void *" or to a type that can be safely accessed by the raw memory function suppresses the warning. --WWnnoonn--vviirrttuuaall--ddttoorr (C++ and Objective-C++ only) Warn when a class has virtual functions and an accessible non-vir- tual destructor itself or in an accessible polymorphic base class, in which case it is possible but unsafe to delete an instance of a derived class through a pointer to the class itself or base class. This warning is automatically enabled if --WWeeffffcc++++ is specified. --WWrreeggiisstteerr (C++ and Objective-C++ only) Warn on uses of the "register" storage class specifier, except when it is part of the GNU EExxpplliicciitt RReeggiisstteerr VVaarriiaabblleess extension. The use of the "register" keyword as storage class specifier has been deprecated in C++11 and removed in C++17. Enabled by default with --ssttdd==cc++++1177. --WWrreeoorrddeerr (C++ and Objective-C++ only) Warn when the order of member initializers given in the code does not match the order in which they must be executed. For instance: struct A { int i; int j; A(): j (0), i (1) { } }; The compiler rearranges the member initializers for "i" and "j" to match the declaration order of the members, emitting a warning to that effect. This warning is enabled by --WWaallll. --WWnnoo--ppeessssiimmiizziinngg--mmoovvee (C++ and Objective-C++ only) This warning warns when a call to "std::move" prevents copy eli- sion. A typical scenario when copy elision can occur is when re- turning in a function with a class return type, when the expression being returned is the name of a non-volatile automatic object, and is not a function parameter, and has the same type as the function return type. struct T { ... }; T fn() { T t; ... return std::move (t); } But in this example, the "std::move" call prevents copy elision. This warning is enabled by --WWaallll. --WWnnoo--rreedduunnddaanntt--mmoovvee (C++ and Objective-C++ only) This warning warns about redundant calls to "std::move"; that is, when a move operation would have been performed even without the "std::move" call. This happens because the compiler is forced to treat the object as if it were an rvalue in certain situations such as returning a local variable, where copy elision isn't applicable. Consider: struct T { ... }; T fn(T t) { ... return std::move (t); } Here, the "std::move" call is redundant. Because G++ implements Core Issue 1579, another example is: struct T { // convertible to U ... }; struct U { ... }; U fn() { T t; ... return std::move (t); } In this example, copy elision isn't applicable because the type of the expression being returned and the function return type differ, yet G++ treats the return value as if it were designated by an rvalue. This warning is enabled by --WWeexxttrraa. --WWrraannggee--lloooopp--ccoonnssttrruucctt (C++ and Objective-C++ only) This warning warns when a C++ range-based for-loop is creating an unnecessary copy. This can happen when the range declaration is not a reference, but probably should be. For example: struct S { char arr[128]; }; void fn () { S arr[5]; for (const auto x : arr) { ... } } It does not warn when the type being copied is a trivially-copyable type whose size is less than 64 bytes. This warning also warns when a loop variable in a range-based for- loop is initialized with a value of a different type resulting in a copy. For example: void fn() { int arr[10]; for (const double &x : arr) { ... } } In the example above, in every iteration of the loop a temporary value of type "double" is created and destroyed, to which the ref- erence "const double &" is bound. This warning is enabled by --WWaallll. --WWrreedduunnddaanntt--ttaaggss (C++ and Objective-C++ only) Warn about redundant class-key and enum-key in references to class types and enumerated types in contexts where the key can be elimi- nated without causing an ambiguity. For example: struct foo; struct foo *p; // warn that keyword struct can be eliminated On the other hand, in this example there is no warning: struct foo; void foo (); // "hides" struct foo void bar (struct foo&); // no warning, keyword struct is necessary --WWnnoo--ssuubboobbjjeecctt--lliinnkkaaggee (C++ and Objective-C++ only) Do not warn if a class type has a base or a field whose type uses the anonymous namespace or depends on a type with no linkage. If a type A depends on a type B with no or internal linkage, defining it in multiple translation units would be an ODR violation because the meaning of B is different in each translation unit. If A only ap- pears in a single translation unit, the best way to silence the warning is to give it internal linkage by putting it in an anony- mous namespace as well. The compiler doesn't give this warning for types defined in the main .C file, as those are unlikely to have multiple definitions. --WWssuubboobbjjeecctt--lliinnkkaaggee is enabled by default. --WWeeffffcc++++ (C++ and Objective-C++ only) Warn about violations of the following style guidelines from Scott Meyers' _E_f_f_e_c_t_i_v_e _C_+_+ series of books: * Define a copy constructor and an assignment operator for classes with dynamically-allocated memory. * Prefer initialization to assignment in constructors. * Have "operator=" return a reference to *this. * Don't try to return a reference when you must return an object. * Distinguish between prefix and postfix forms of increment and decrement operators. * Never overload "&&", "||", or ",". This option also enables --WWnnoonn--vviirrttuuaall--ddttoorr, which is also one of the effective C++ recommendations. However, the check is extended to warn about the lack of virtual destructor in accessible non- polymorphic bases classes too. When selecting this option, be aware that the standard library headers do not obey all of these guidelines; use ggrreepp --vv to filter out those warnings. --WWnnoo--eexxcceeppttiioonnss (C++ and Objective-C++ only) Disable the warning about the case when an exception handler is shadowed by another handler, which can point out a wrong ordering of exception handlers. --WWssttrriicctt--nnuullll--sseennttiinneell (C++ and Objective-C++ only) Warn about the use of an uncasted "NULL" as sentinel. When compil- ing only with GCC this is a valid sentinel, as "NULL" is defined to "__null". Although it is a null pointer constant rather than a null pointer, it is guaranteed to be of the same size as a pointer. But this use is not portable across different compilers. --WWnnoo--nnoonn--tteemmppllaattee--ffrriieenndd (C++ and Objective-C++ only) Disable warnings when non-template friend functions are declared within a template. In very old versions of GCC that predate imple- mentation of the ISO standard, declarations such as ffrriieenndd iinntt ffoooo((iinntt)), where the name of the friend is an unqualified-id, could be interpreted as a particular specialization of a template func- tion; the warning exists to diagnose compatibility problems, and is enabled by default. --WWoolldd--ssttyyllee--ccaasstt (C++ and Objective-C++ only) Warn if an old-style (C-style) cast to a non-void type is used within a C++ program. The new-style casts ("dynamic_cast", "static_cast", "reinterpret_cast", and "const_cast") are less vul- nerable to unintended effects and much easier to search for. --WWoovveerrllooaaddeedd--vviirrttuuaall (C++ and Objective-C++ only) Warn when a function declaration hides virtual functions from a base class. For example, in: struct A { virtual void f(); }; struct B: public A { void f(int); }; the "A" class version of "f" is hidden in "B", and code like: B* b; b->f(); fails to compile. --WWnnoo--ppmmff--ccoonnvveerrssiioonnss (C++ and Objective-C++ only) Disable the diagnostic for converting a bound pointer to member function to a plain pointer. --WWssiiggnn--pprroommoo (C++ and Objective-C++ only) Warn when overload resolution chooses a promotion from unsigned or enumerated type to a signed type, over a conversion to an unsigned type of the same size. Previous versions of G++ tried to preserve unsignedness, but the standard mandates the current behavior. --WWtteemmppllaatteess (C++ and Objective-C++ only) Warn when a primary template declaration is encountered. Some cod- ing rules disallow templates, and this may be used to enforce that rule. The warning is inactive inside a system header file, such as the STL, so one can still use the STL. One may also instantiate or specialize templates. --WWmmiissmmaattcchheedd--nneeww--ddeelleettee (C++ and Objective-C++ only) Warn for mismatches between calls to "operator new" or "operator delete" and the corresponding call to the allocation or dealloca- tion function. This includes invocations of C++ "operator delete" with pointers returned from either mismatched forms of "operator new", or from other functions that allocate objects for which the "operator delete" isn't a suitable deallocator, as well as calls to other deallocation functions with pointers returned from "operator new" for which the deallocation function isn't suitable. For example, the "delete" expression in the function below is diag- nosed because it doesn't match the array form of the "new" expres- sion the pointer argument was returned from. Similarly, the call to "free" is also diagnosed. void f () { int *a = new int[n]; delete a; // warning: mismatch in array forms of expressions char *p = new char[n]; free (p); // warning: mismatch between new and free } The related option --WWmmiissmmaattcchheedd--ddeeaalllloocc diagnoses mismatches in- volving allocation and deallocation functions other than "operator new" and "operator delete". --WWmmiissmmaattcchheedd--nneeww--ddeelleettee is included in --WWaallll. --WWmmiissmmaattcchheedd--ttaaggss (C++ and Objective-C++ only) Warn for declarations of structs, classes, and class templates and their specializations with a class-key that does not match either the definition or the first declaration if no definition is pro- vided. For example, the declaration of "struct Object" in the argument list of "draw" triggers the warning. To avoid it, either remove the redundant class-key "struct" or replace it with "class" to match its definition. class Object { public: virtual ~Object () = 0; }; void draw (struct Object*); It is not wrong to declare a class with the class-key "struct" as the example above shows. The --WWmmiissmmaattcchheedd--ttaaggss option is intended to help achieve a consistent style of class declarations. In code that is intended to be portable to Windows-based compilers the warning helps prevent unresolved references due to the difference in the mangling of symbols declared with different class-keys. The option can be used either on its own or in conjunction with --WWrree-- dduunnddaanntt--ttaaggss. --WWmmuullttiippllee--iinnhheerriittaannccee (C++ and Objective-C++ only) Warn when a class is defined with multiple direct base classes. Some coding rules disallow multiple inheritance, and this may be used to enforce that rule. The warning is inactive inside a system header file, such as the STL, so one can still use the STL. One may also define classes that indirectly use multiple inheritance. --WWvviirrttuuaall--iinnhheerriittaannccee Warn when a class is defined with a virtual direct base class. Some coding rules disallow multiple inheritance, and this may be used to enforce that rule. The warning is inactive inside a system header file, such as the STL, so one can still use the STL. One may also define classes that indirectly use virtual inheritance. --WWnnoo--vviirrttuuaall--mmoovvee--aassssiiggnn Suppress warnings about inheriting from a virtual base with a non- trivial C++11 move assignment operator. This is dangerous because if the virtual base is reachable along more than one path, it is moved multiple times, which can mean both objects end up in the moved-from state. If the move assignment operator is written to avoid moving from a moved-from object, this warning can be dis- abled. --WWnnaammeessppaacceess Warn when a namespace definition is opened. Some coding rules dis- allow namespaces, and this may be used to enforce that rule. The warning is inactive inside a system header file, such as the STL, so one can still use the STL. One may also use using directives and qualified names. --WWnnoo--tteerrmmiinnaattee (C++ and Objective-C++ only) Disable the warning about a throw-expression that will immediately result in a call to "terminate". --WWnnoo--vveexxiinngg--ppaarrssee (C++ and Objective-C++ only) Warn about the most vexing parse syntactic ambiguity. This warns about the cases when a declaration looks like a variable defini- tion, but the C++ language requires it to be interpreted as a func- tion declaration. For instance: void f(double a) { int i(); // extern int i (void); int n(int(a)); // extern int n (int); } Another example: struct S { S(int); }; void f(double a) { S x(int(a)); // extern struct S x (int); S y(int()); // extern struct S y (int (*) (void)); S z(); // extern struct S z (void); } The warning will suggest options how to deal with such an ambigu- ity; e.g., it can suggest removing the parentheses or using braces instead. This warning is enabled by default. --WWnnoo--ccllaassss--ccoonnvveerrssiioonn (C++ and Objective-C++ only) Do not warn when a conversion function converts an object to the same type, to a base class of that type, or to void; such a conver- sion function will never be called. --WWvvoollaattiillee (C++ and Objective-C++ only) Warn about deprecated uses of the "volatile" qualifier. This in- cludes postfix and prefix "++" and "--" expressions of "volatile"-qualified types, using simple assignments where the left operand is a "volatile"-qualified non-class type for their value, compound assignments where the left operand is a "volatile"-quali- fied non-class type, "volatile"-qualified function return type, "volatile"-qualified parameter type, and structured bindings of a "volatile"-qualified type. This usage was deprecated in C++20. Enabled by default with --ssttdd==cc++++2200. --WWzzeerroo--aass--nnuullll--ppooiinntteerr--ccoonnssttaanntt (C++ and Objective-C++ only) Warn when a literal 00 is used as null pointer constant. This can be useful to facilitate the conversion to "nullptr" in C++11. --WWaalliiggnneedd--nneeww Warn about a new-expression of a type that requires greater align- ment than the "alignof(std::max_align_t)" but uses an allocation function without an explicit alignment parameter. This option is enabled by --WWaallll. Normally this only warns about global allocation functions, but --WWaalliiggnneedd--nneeww==aallll also warns about class member allocation func- tions. --WWnnoo--ppllaacceemmeenntt--nneeww --WWppllaacceemmeenntt--nneeww==_n Warn about placement new expressions with undefined behavior, such as constructing an object in a buffer that is smaller than the type of the object. For example, the placement new expression below is diagnosed because it attempts to construct an array of 64 integers in a buffer only 64 bytes large. char buf [64]; new (buf) int[64]; This warning is enabled by default. --WWppllaacceemmeenntt--nneeww==11 This is the default warning level of --WWppllaacceemmeenntt--nneeww. At this level the warning is not issued for some strictly undefined constructs that GCC allows as extensions for compatibility with legacy code. For example, the following "new" expression is not diagnosed at this level even though it has undefined behav- ior according to the C++ standard because it writes past the end of the one-element array. struct S { int n, a[1]; }; S *s = (S *)malloc (sizeof *s + 31 * sizeof s->a[0]); new (s->a)int [32](); --WWppllaacceemmeenntt--nneeww==22 At this level, in addition to diagnosing all the same con- structs as at level 1, a diagnostic is also issued for place- ment new expressions that construct an object in the last mem- ber of structure whose type is an array of a single element and whose size is less than the size of the object being construc- ted. While the previous example would be diagnosed, the fol- lowing construct makes use of the flexible member array exten- sion to avoid the warning at level 2. struct S { int n, a[]; }; S *s = (S *)malloc (sizeof *s + 32 * sizeof s->a[0]); new (s->a)int [32](); --WWccaattcchh--vvaalluuee --WWccaattcchh--vvaalluuee==_n (C++ and Objective-C++ only) Warn about catch handlers that do not catch via reference. With --WWccaattcchh--vvaalluuee==11 (or --WWccaattcchh--vvaalluuee for short) warn about polymorphic class types that are caught by value. With --WWccaattcchh--vvaalluuee==22 warn about all class types that are caught by value. With --WWccaattcchh--vvaalluuee==33 warn about all types that are not caught by refer- ence. --WWccaattcchh--vvaalluuee is enabled by --WWaallll. --WWccoonnddiittiioonnaallllyy--ssuuppppoorrtteedd (C++ and Objective-C++ only) Warn for conditionally-supported (C++11 [intro.defs]) constructs. --WWnnoo--ddeelleettee--iinnccoommpplleettee (C++ and Objective-C++ only) Do not warn when deleting a pointer to incomplete type, which may cause undefined behavior at runtime. This warning is enabled by default. --WWeexxttrraa--sseemmii (C++, Objective-C++ only) Warn about redundant semicolons after in-class function defini- tions. --WWnnoo--iinnaacccceessssiibbllee--bbaassee (C++, Objective-C++ only) This option controls warnings when a base class is inaccessible in a class derived from it due to ambiguity. The warning is enabled by default. Note that the warning for ambiguous virtual bases is enabled by the --WWeexxttrraa option. struct A { int a; }; struct B : A { }; struct C : B, A { }; --WWnnoo--iinnhheerriitteedd--vvaarriiaaddiicc--ccttoorr Suppress warnings about use of C++11 inheriting constructors when the base class inherited from has a C variadic constructor; the warning is on by default because the ellipsis is not inherited. --WWnnoo--iinnvvaalliidd--ooffffsseettooff (C++ and Objective-C++ only) Suppress warnings from applying the "offsetof" macro to a non-POD type. According to the 2014 ISO C++ standard, applying "offsetof" to a non-standard-layout type is undefined. In existing C++ imple- mentations, however, "offsetof" typically gives meaningful results. This flag is for users who are aware that they are writing non- portable code and who have deliberately chosen to ignore the warn- ing about it. The restrictions on "offsetof" may be relaxed in a future version of the C++ standard. --WWssiizzeedd--ddeeaallllooccaattiioonn (C++ and Objective-C++ only) Warn about a definition of an unsized deallocation function void operator delete (void *) noexcept; void operator delete[] (void *) noexcept; without a definition of the corresponding sized deallocation func- tion void operator delete (void *, std::size_t) noexcept; void operator delete[] (void *, std::size_t) noexcept; or vice versa. Enabled by --WWeexxttrraa along with --ffssiizzeedd--ddeeaallllooccaattiioonn. --WWssuuggggeesstt--ffiinnaall--ttyyppeess Warn about types with virtual methods where code quality would be improved if the type were declared with the C++11 "final" speci- fier, or, if possible, declared in an anonymous namespace. This al- lows GCC to more aggressively devirtualize the polymorphic calls. This warning is more effective with link-time optimization, where the information about the class hierarchy graph is more complete. --WWssuuggggeesstt--ffiinnaall--mmeetthhooddss Warn about virtual methods where code quality would be improved if the method were declared with the C++11 "final" specifier, or, if possible, its type were declared in an anonymous namespace or with the "final" specifier. This warning is more effective with link- time optimization, where the information about the class hierarchy graph is more complete. It is recommended to first consider sugges- tions of --WWssuuggggeesstt--ffiinnaall--ttyyppeess and then rebuild with new annota- tions. --WWssuuggggeesstt--oovveerrrriiddee Warn about overriding virtual functions that are not marked with the "override" keyword. --WWuussee--aafftteerr--ffrreeee --WWuussee--aafftteerr--ffrreeee==_n Warn about uses of pointers to dynamically allocated objects that have been rendered indeterminate by a call to a deallocation func- tion. The warning is enabled at all optimization levels but may yield different results with optimization than without. --WWuussee--aafftteerr--ffrreeee==11 At level 1 the warning attempts to diagnose only unconditional uses of pointers made indeterminate by a deallocation call or a successful call to "realloc", regardless of whether or not the call resulted in an actual reallocatio of memory. This in- cludes double-"free" calls as well as uses in arithmetic and relational expressions. Although undefined, uses of indetermi- nate pointers in equality (or inequality) expressions are not diagnosed at this level. --WWuussee--aafftteerr--ffrreeee==22 At level 2, in addition to unconditional uses, the warning also diagnoses conditional uses of pointers made indeterminate by a deallocation call. As at level 2, uses in equality (or in- equality) expressions are not diagnosed. For example, the sec- ond call to "free" in the following function is diagnosed at this level: struct A { int refcount; void *data; }; void release (struct A *p) { int refcount = --p->refcount; free (p); if (refcount == 0) free (p->data); // warning: p may be used after free } --WWuussee--aafftteerr--ffrreeee==33 At level 3, the warning also diagnoses uses of indeterminate pointers in equality expressions. All uses of indeterminate pointers are undefined but equality tests sometimes appear af- ter calls to "realloc" as an attempt to determine whether the call resulted in relocating the object to a different address. They are diagnosed at a separate level to aid legacy code grad- ually transition to safe alternatives. For example, the equal- ity test in the function below is diagnosed at this level: void adjust_pointers (int**, int); void grow (int **p, int n) { int **q = (int**)realloc (p, n *= 2); if (q == p) return; adjust_pointers ((int**)q, n); } To avoid the warning at this level, store offsets into allo- cated memory instead of pointers. This approach obviates need- ing to adjust the stored pointers after reallocation. --WWuussee--aafftteerr--ffrreeee==22 is included in --WWaallll. --WWuusseelleessss--ccaasstt (C++ and Objective-C++ only) Warn when an expression is casted to its own type. --WWnnoo--ccoonnvveerrssiioonn--nnuullll (C++ and Objective-C++ only) Do not warn for conversions between "NULL" and non-pointer types. --WWccoonnvveerrssiioonn--nnuullll is enabled by default. OOppttiioonnss CCoonnttrroolllliinngg OObbjjeeccttiivvee--CC aanndd OObbjjeeccttiivvee--CC++++ DDiiaalleeccttss (NOTE: This manual does not describe the Objective-C and Objective-C++ languages themselves. This section describes the command-line options that are only meaning- ful for Objective-C and Objective-C++ programs. You can also use most of the language-independent GNU compiler options. For example, you might compile a file _s_o_m_e___c_l_a_s_s_._m like this: gcc -g -fgnu-runtime -O -c some_class.m In this example, --ffggnnuu--rruunnttiimmee is an option meant only for Objective-C and Objective-C++ programs; you can use the other options with any lan- guage supported by GCC. Note that since Objective-C is an extension of the C language, Objec- tive-C compilations may also use options specific to the C front-end (e.g., --WWttrraaddiittiioonnaall). Similarly, Objective-C++ compilations may use C++-specific options (e.g., --WWaabbii). Here is a list of options that are _o_n_l_y for compiling Objective-C and Objective-C++ programs: --ffccoonnssttaanntt--ssttrriinngg--ccllaassss==_c_l_a_s_s_-_n_a_m_e Use _c_l_a_s_s_-_n_a_m_e as the name of the class to instantiate for each literal string specified with the syntax "@"..."". The default class name is "NXConstantString" if the GNU runtime is being used, and "NSConstantString" if the NeXT runtime is being used (see be- low). The --ffccoonnssttaanntt--ccffssttrriinnggss option, if also present, overrides the --ffccoonnssttaanntt--ssttrriinngg--ccllaassss setting and cause "@"..."" literals to be laid out as constant CoreFoundation strings. --ffggnnuu--rruunnttiimmee Generate object code compatible with the standard GNU Objective-C runtime. This is the default for most types of systems. --ffnneexxtt--rruunnttiimmee Generate output compatible with the NeXT runtime. This is the de- fault for NeXT-based systems, including Darwin and Mac OS X. The macro "__NEXT_RUNTIME__" is predefined if (and only if) this option is used. --ffnnoo--nniill--rreecceeiivveerrss Assume that all Objective-C message dispatches ("[receiver mes- sage:arg]") in this translation unit ensure that the receiver is not "nil". This allows for more efficient entry points in the run- time to be used. This option is only available in conjunction with the NeXT runtime and ABI version 0 or 1. --ffoobbjjcc--aabbii--vveerrssiioonn==_n Use version _n of the Objective-C ABI for the selected runtime. This option is currently supported only for the NeXT runtime. In that case, Version 0 is the traditional (32-bit) ABI without sup- port for properties and other Objective-C 2.0 additions. Version 1 is the traditional (32-bit) ABI with support for properties and other Objective-C 2.0 additions. Version 2 is the modern (64-bit) ABI. If nothing is specified, the default is Version 0 on 32-bit target machines, and Version 2 on 64-bit target machines. --ffoobbjjcc--ccaallll--ccxxxx--ccddttoorrss For each Objective-C class, check if any of its instance variables is a C++ object with a non-trivial default constructor. If so, synthesize a special "- (id) .cxx_construct" instance method which runs non-trivial default constructors on any such instance vari- ables, in order, and then return "self". Similarly, check if any instance variable is a C++ object with a non-trivial destructor, and if so, synthesize a special "- (void) .cxx_destruct" method which runs all such default destructors, in reverse order. The "- (id) .cxx_construct" and "- (void) .cxx_destruct" methods thusly generated only operate on instance variables declared in the current Objective-C class, and not those inherited from super- classes. It is the responsibility of the Objective-C runtime to invoke all such methods in an object's inheritance hierarchy. The "- (id) .cxx_construct" methods are invoked by the runtime immedi- ately after a new object instance is allocated; the "- (void) .cxx_destruct" methods are invoked immediately before the runtime deallocates an object instance. As of this writing, only the NeXT runtime on Mac OS X 10.4 and later has support for invoking the "- (id) .cxx_construct" and "- (void) .cxx_destruct" methods. --ffoobbjjcc--ddiirreecctt--ddiissppaattcchh Allow fast jumps to the message dispatcher. On Darwin this is ac- complished via the comm page. --ffoobbjjcc--eexxcceeppttiioonnss Enable syntactic support for structured exception handling in Ob- jective-C, similar to what is offered by C++. This option is re- quired to use the Objective-C keywords @try, @throw, @catch, @fi- nally and @synchronized. This option is available with both the GNU runtime and the NeXT runtime (but not available in conjunction with the NeXT runtime on Mac OS X 10.2 and earlier). --ffoobbjjcc--ggcc Enable garbage collection (GC) in Objective-C and Objective-C++ programs. This option is only available with the NeXT runtime; the GNU runtime has a different garbage collection implementation that does not require special compiler flags. --ffoobbjjcc--nniillcchheecckk For the NeXT runtime with version 2 of the ABI, check for a nil re- ceiver in method invocations before doing the actual method call. This is the default and can be disabled using --ffnnoo--oobbjjcc--nniillcchheecckk. Class methods and super calls are never checked for nil in this way no matter what this flag is set to. Currently this flag does noth- ing when the GNU runtime, or an older version of the NeXT runtime ABI, is used. --ffoobbjjcc--ssttdd==oobbjjcc11 Conform to the language syntax of Objective-C 1.0, the language recognized by GCC 4.0. This only affects the Objective-C additions to the C/C++ language; it does not affect conformance to C/C++ standards, which is controlled by the separate C/C++ dialect option flags. When this option is used with the Objective-C or Objec- tive-C++ compiler, any Objective-C syntax that is not recognized by GCC 4.0 is rejected. This is useful if you need to make sure that your Objective-C code can be compiled with older versions of GCC. --ffrreeppllaaccee--oobbjjcc--ccllaasssseess Emit a special marker instructing _ll_dd((11)) not to statically link in the resulting object file, and allow _dd_yy_ll_dd((11)) to load it in at run time instead. This is used in conjunction with the Fix-and-Con- tinue debugging mode, where the object file in question may be re- compiled and dynamically reloaded in the course of program execu- tion, without the need to restart the program itself. Currently, Fix-and-Continue functionality is only available in conjunction with the NeXT runtime on Mac OS X 10.3 and later. --ffzzeerroo--lliinnkk When compiling for the NeXT runtime, the compiler ordinarily re- places calls to "objc_getClass("...")" (when the name of the class is known at compile time) with static class references that get initialized at load time, which improves run-time performance. Specifying the --ffzzeerroo--lliinnkk flag suppresses this behavior and causes calls to "objc_getClass("...")" to be retained. This is useful in Zero-Link debugging mode, since it allows for individual class im- plementations to be modified during program execution. The GNU runtime currently always retains calls to "objc_get_class("...")" regardless of command-line options. --ffnnoo--llooccaall--iivvaarrss By default instance variables in Objective-C can be accessed as if they were local variables from within the methods of the class they're declared in. This can lead to shadowing between instance variables and other variables declared either locally inside a class method or globally with the same name. Specifying the --ffnnoo--llooccaall--iivvaarrss flag disables this behavior thus avoiding variable shadowing issues. --ffiivvaarr--vviissiibbiilliittyy==[ppuubblliicc|pprrootteecctteedd|pprriivvaattee|ppaacckkaaggee] Set the default instance variable visibility to the specified op- tion so that instance variables declared outside the scope of any access modifier directives default to the specified visibility. --ggeenn--ddeeccllss Dump interface declarations for all classes seen in the source file to a file named _s_o_u_r_c_e_n_a_m_e_._d_e_c_l. --WWaassssiiggnn--iinntteerrcceepptt (Objective-C and Objective-C++ only) Warn whenever an Objective-C assignment is being intercepted by the garbage collector. --WWnnoo--pprrooppeerrttyy--aassssiiggnn--ddeeffaauulltt (Objective-C and Objective-C++ only) Do not warn if a property for an Objective-C object has no assign semantics specified. --WWnnoo--pprroottooccooll (Objective-C and Objective-C++ only) If a class is declared to implement a protocol, a warning is issued for every method in the protocol that is not implemented by the class. The default behavior is to issue a warning for every method not explicitly implemented in the class, even if a method implemen- tation is inherited from the superclass. If you use the --WWnnoo--pprroo-- ttooccooll option, then methods inherited from the superclass are con- sidered to be implemented, and no warning is issued for them. --WWoobbjjcc--rroooott--ccllaassss (Objective-C and Objective-C++ only) Warn if a class interface lacks a superclass. Most classes will in- herit from "NSObject" (or "Object") for example. When declaring classes intended to be root classes, the warning can be suppressed by marking their interfaces with "__attri- bute__((objc_root_class))". --WWsseelleeccttoorr (Objective-C and Objective-C++ only) Warn if multiple methods of different types for the same selector are found during compilation. The check is performed on the list of methods in the final stage of compilation. Additionally, a check is performed for each selector appearing in a "@selec- tor(...)" expression, and a corresponding method for that selector has been found during compilation. Because these checks scan the method table only at the end of compilation, these warnings are not produced if the final stage of compilation is not reached, for ex- ample because an error is found during compilation, or because the --ffssyynnttaaxx--oonnllyy option is being used. --WWssttrriicctt--sseelleeccttoorr--mmaattcchh (Objective-C and Objective-C++ only) Warn if multiple methods with differing argument and/or return types are found for a given selector when attempting to send a mes- sage using this selector to a receiver of type "id" or "Class". When this flag is off (which is the default behavior), the compiler omits such warnings if any differences found are confined to types that share the same size and alignment. --WWuunnddeeccllaarreedd--sseelleeccttoorr (Objective-C and Objective-C++ only) Warn if a "@selector(...)" expression referring to an undeclared selector is found. A selector is considered undeclared if no method with that name has been declared before the "@selector(...)" expression, either explicitly in an @interface or @protocol decla- ration, or implicitly in an @implementation section. This option always performs its checks as soon as a "@selector(...)" expression is found, while --WWsseelleeccttoorr only performs its checks in the final stage of compilation. This also enforces the coding style conven- tion that methods and selectors must be declared before being used. --pprriinntt--oobbjjcc--rruunnttiimmee--iinnffoo Generate C header describing the largest structure that is passed by value, if any. OOppttiioonnss ttoo CCoonnttrrooll DDiiaaggnnoossttiicc MMeessssaaggeess FFoorrmmaattttiinngg Traditionally, diagnostic messages have been formatted irrespective of the output device's aspect (e.g. its width, ...). You can use the op- tions described below to control the formatting algorithm for diagnos- tic messages, e.g. how many characters per line, how often source loca- tion information should be reported. Note that some language front ends may not honor these options. --ffmmeessssaaggee--lleennggtthh==_n Try to format error messages so that they fit on lines of about _n characters. If _n is zero, then no line-wrapping is done; each er- ror message appears on a single line. This is the default for all front ends. Note - this option also affects the display of the ##eerrrroorr and ##wwaarrnniinngg pre-processor directives, and the ddeepprreeccaatteedd func- tion/type/variable attribute. It does not however affect the pprraaggmmaa GGCCCC wwaarrnniinngg and pprraaggmmaa GGCCCC eerrrroorr pragmas. --ffddiiaaggnnoossttiiccss--ppllaaiinn--oouuttppuutt This option requests that diagnostic output look as plain as possi- ble, which may be useful when running ddeejjaaggnnuu or other utilities that need to parse diagnostics output and prefer that it remain more stable over time. --ffddiiaaggnnoossttiiccss--ppllaaiinn--oouuttppuutt is currently equivalent to the following options: --ffnnoo--ddiiaaggnnoossttiiccss--sshhooww--ccaarreett --ffnnoo--ddiiaaggnnoossttiiccss--sshhooww--lliinnee--nnuummbbeerrss --ffddiiaaggnnoossttiiccss--ccoolloorr==nneevveerr --ffddii-- aaggnnoossttiiccss--uurrllss==nneevveerr --ffddiiaaggnnoossttiiccss--ppaatthh--ffoorrmmaatt==sseeppaarraattee--eevveennttss In the future, if GCC changes the default appearance of its diagnos- tics, the corresponding option to disable the new behavior will be added to this list. --ffddiiaaggnnoossttiiccss--sshhooww--llooccaattiioonn==oonnccee Only meaningful in line-wrapping mode. Instructs the diagnostic messages reporter to emit source location information _o_n_c_e; that is, in case the message is too long to fit on a single physical line and has to be wrapped, the source location won't be emitted (as prefix) again, over and over, in subsequent continuation lines. This is the default behavior. --ffddiiaaggnnoossttiiccss--sshhooww--llooccaattiioonn==eevveerryy--lliinnee Only meaningful in line-wrapping mode. Instructs the diagnostic messages reporter to emit the same source location information (as prefix) for physical lines that result from the process of breaking a message which is too long to fit on a single line. --ffddiiaaggnnoossttiiccss--ccoolloorr[[==_W_H_E_N]] --ffnnoo--ddiiaaggnnoossttiiccss--ccoolloorr Use color in diagnostics. _W_H_E_N is nneevveerr, aallwwaayyss, or aauuttoo. The de- fault depends on how the compiler has been configured, it can be any of the above _W_H_E_N options or also nneevveerr if GGCCCC__CCOOLLOORRSS environ- ment variable isn't present in the environment, and aauuttoo otherwise. aauuttoo makes GCC use color only when the standard error is a termi- nal, and when not executing in an emacs shell. The forms --ffddiiaagg-- nnoossttiiccss--ccoolloorr and --ffnnoo--ddiiaaggnnoossttiiccss--ccoolloorr are aliases for --ffddiiaaggnnooss-- ttiiccss--ccoolloorr==aallwwaayyss and --ffddiiaaggnnoossttiiccss--ccoolloorr==nneevveerr, respectively. The colors are defined by the environment variable GGCCCC__CCOOLLOORRSS. Its value is a colon-separated list of capabilities and Select Graphic Rendition (SGR) substrings. SGR commands are interpreted by the terminal or terminal emulator. (See the section in the documenta- tion of your text terminal for permitted values and their meanings as character attributes.) These substring values are integers in decimal representation and can be concatenated with semicolons. Common values to concatenate include 11 for bold, 44 for underline, 55 for blink, 77 for inverse, 3399 for default foreground color, 3300 to 3377 for foreground colors, 9900 to 9977 for 16-color mode foreground col- ors, 3388;;55;;00 to 3388;;55;;225555 for 88-color and 256-color modes foreground colors, 4499 for default background color, 4400 to 4477 for background colors, 110000 to 110077 for 16-color mode background colors, and 4488;;55;;00 to 4488;;55;;225555 for 88-color and 256-color modes background colors. The default GGCCCC__CCOOLLOORRSS is error=01;31:warning=01;35:note=01;36:range1=32:range2=34:locus=01:\ quote=01:path=01;36:fixit-insert=32:fixit-delete=31:\ diff-filename=01:diff-hunk=32:diff-delete=31:diff-insert=32:\ type-diff=01;32 where 0011;;3311 is bold red, 0011;;3355 is bold magenta, 0011;;3366 is bold cyan, 3322 is green, 3344 is blue, 0011 is bold, and 3311 is red. Setting GGCCCC__CCOOLLOORRSS to the empty string disables colors. Supported capabil- ities are as follows. "error=" SGR substring for error: markers. "warning=" SGR substring for warning: markers. "note=" SGR substring for note: markers. "path=" SGR substring for colorizing paths of control-flow events as printed via --ffddiiaaggnnoossttiiccss--ppaatthh--ffoorrmmaatt==, such as the identifiers of individual events and lines indicating interprocedural calls and returns. "range1=" SGR substring for first additional range. "range2=" SGR substring for second additional range. "locus=" SGR substring for location information, ffiillee::lliinnee or ffiillee::lliinnee::ccoolluummnn etc. "quote=" SGR substring for information printed within quotes. "fixit-insert=" SGR substring for fix-it hints suggesting text to be inserted or replaced. "fixit-delete=" SGR substring for fix-it hints suggesting text to be deleted. "diff-filename=" SGR substring for filename headers within generated patches. "diff-hunk=" SGR substring for the starts of hunks within generated patches. "diff-delete=" SGR substring for deleted lines within generated patches. "diff-insert=" SGR substring for inserted lines within generated patches. "type-diff=" SGR substring for highlighting mismatching types within tem- plate arguments in the C++ frontend. --ffddiiaaggnnoossttiiccss--uurrllss[[==_W_H_E_N]] Use escape sequences to embed URLs in diagnostics. For example, when --ffddiiaaggnnoossttiiccss--sshhooww--ooppttiioonn emits text showing the command-line option controlling a diagnostic, embed a URL for documentation of that option. _W_H_E_N is nneevveerr, aallwwaayyss, or aauuttoo. aauuttoo makes GCC use URL escape se- quences only when the standard error is a terminal, and when not executing in an emacs shell or any graphical terminal which is known to be incompatible with this feature, see below. The default depends on how the compiler has been configured. It can be any of the above _W_H_E_N options. GCC can also be configured (via the ----wwiitthh--ddiiaaggnnooss-- ttiiccss--uurrllss==aauuttoo--iiff--eennvv configure-time option) so that the default is affected by environment variables. Under such a configuration, GCC defaults to using aauuttoo if either GGCCCC__UURRLLSS or TTEERRMM__UURRLLSS environment variables are present and non-empty in the environment of the com- piler, or nneevveerr if neither are. However, even with --ffddiiaaggnnoossttiiccss--uurrllss==aallwwaayyss the behavior is depen- dent on those environment variables: If GGCCCC__UURRLLSS is set to empty or nnoo, do not embed URLs in diagnostics. If set to sstt, URLs use ST escape sequences. If set to bbeell, the default, URLs use BEL escape sequences. Any other non-empty value enables the feature. If GGCCCC__UURRLLSS is not set, use TTEERRMM__UURRLLSS as a fallback. Note: ST is an ANSI escape sequence, string terminator EESSCC \\, BEL is an ASCII character, CTRL-G that usually sounds like a beep. At this time GCC tries to detect also a few terminals that are known to not implement the URL feature, and have bugs or at least had bugs in some versions that are still in use, where the URL es- capes are likely to misbehave, i.e. print garbage on the screen. That list is currently xfce4-terminal, certain known to be buggy gnome-terminal versions, the linux console, and mingw. This check can be skipped with the --ffddiiaaggnnoossttiiccss--uurrllss==aallwwaayyss. --ffnnoo--ddiiaaggnnoossttiiccss--sshhooww--ooppttiioonn By default, each diagnostic emitted includes text indicating the command-line option that directly controls the diagnostic (if such an option is known to the diagnostic machinery). Specifying the --ffnnoo--ddiiaaggnnoossttiiccss--sshhooww--ooppttiioonn flag suppresses that behavior. --ffnnoo--ddiiaaggnnoossttiiccss--sshhooww--ccaarreett By default, each diagnostic emitted includes the original source line and a caret ^^ indicating the column. This option suppresses this information. The source line is truncated to _n characters, if the --ffmmeessssaaggee--lleennggtthh==nn option is given. When the output is done to the terminal, the width is limited to the width given by the CCOOLL-- UUMMNNSS environment variable or, if not set, to the terminal width. --ffnnoo--ddiiaaggnnoossttiiccss--sshhooww--llaabbeellss By default, when printing source code (via --ffddiiaaggnnooss-- ttiiccss--sshhooww--ccaarreett), diagnostics can label ranges of source code with pertinent information, such as the types of expressions: printf ("foo %s bar", long_i + long_j); ~^ ~~~~~~~~~~~~~~~ | | char * long int This option suppresses the printing of these labels (in the example above, the vertical bars and the "char *" and "long int" text). --ffnnoo--ddiiaaggnnoossttiiccss--sshhooww--ccwwee Diagnostic messages can optionally have an associated @url{https://cwe.mitre.org/index.html, CWE} identifier. GCC itself only provides such metadata for some of the --ffaannaallyyzzeerr diagnostics. GCC plugins may also provide diagnostics with such metadata. By default, if this information is present, it will be printed with the diagnostic. This option suppresses the printing of this meta- data. --ffnnoo--ddiiaaggnnoossttiiccss--sshhooww--lliinnee--nnuummbbeerrss By default, when printing source code (via --ffddiiaaggnnooss-- ttiiccss--sshhooww--ccaarreett), a left margin is printed, showing line numbers. This option suppresses this left margin. --ffddiiaaggnnoossttiiccss--mmiinniimmuumm--mmaarrggiinn--wwiiddtthh==_w_i_d_t_h This option controls the minimum width of the left margin printed by --ffddiiaaggnnoossttiiccss--sshhooww--lliinnee--nnuummbbeerrss. It defaults to 6. --ffddiiaaggnnoossttiiccss--ppaarrsseeaabbllee--ffiixxiittss Emit fix-it hints in a machine-parseable format, suitable for con- sumption by IDEs. For each fix-it, a line will be printed after the relevant diagnostic, starting with the string "fix-it:". For example: fix-it:"test.c":{45:3-45:21}:"gtk_widget_show_all" The location is expressed as a half-open range, expressed as a count of bytes, starting at byte 1 for the initial column. In the above example, bytes 3 through 20 of line 45 of "test.c" are to be replaced with the given string: 00000000011111111112222222222 12345678901234567890123456789 gtk_widget_showall (dlg); ^^^^^^^^^^^^^^^^^^ gtk_widget_show_all The filename and replacement string escape backslash as "\\", tab as "\t", newline as "\n", double quotes as "\"", non-printable characters as octal (e.g. vertical tab as "\013"). An empty replacement string indicates that the given range is to be removed. An empty range (e.g. "45:3-45:3") indicates that the string is to be inserted at the given position. --ffddiiaaggnnoossttiiccss--ggeenneerraattee--ppaattcchh Print fix-it hints to stderr in unified diff format, after any di- agnostics are printed. For example: --- test.c +++ test.c @ -42,5 +42,5 @ void show_cb(GtkDialog *dlg) { - gtk_widget_showall(dlg); + gtk_widget_show_all(dlg); } The diff may or may not be colorized, following the same rules as for diagnostics (see --ffddiiaaggnnoossttiiccss--ccoolloorr). --ffddiiaaggnnoossttiiccss--sshhooww--tteemmppllaattee--ttrreeee In the C++ frontend, when printing diagnostics showing mismatching template types, such as: could not convert 'std::map >()' from 'map<[...],vector>' to 'map<[...],vector> the --ffddiiaaggnnoossttiiccss--sshhooww--tteemmppllaattee--ttrreeee flag enables printing a tree- like structure showing the common and differing parts of the types, such as: map< [...], vector< [double != float]>> The parts that differ are highlighted with color ("double" and "float" in this case). --ffnnoo--eelliiddee--ttyyppee By default when the C++ frontend prints diagnostics showing mis- matching template types, common parts of the types are printed as "[...]" to simplify the error message. For example: could not convert 'std::map >()' from 'map<[...],vector>' to 'map<[...],vector> Specifying the --ffnnoo--eelliiddee--ttyyppee flag suppresses that behavior. This flag also affects the output of the --ffddiiaaggnnoossttiiccss--sshhooww--tteemm-- ppllaattee--ttrreeee flag. --ffddiiaaggnnoossttiiccss--ppaatthh--ffoorrmmaatt==_K_I_N_D Specify how to print paths of control-flow events for diagnostics that have such a path associated with them. _K_I_N_D is nnoonnee, sseeppaarraattee--eevveennttss, or iinnlliinnee--eevveennttss, the default. nnoonnee means to not print diagnostic paths. sseeppaarraattee--eevveennttss means to print a separate "note" diagnostic for each event within the diagnostic. For example: test.c:29:5: error: passing NULL as argument 1 to 'PyList_Append' which requires a non-NULL parameter test.c:25:10: note: (1) when 'PyList_New' fails, returning NULL test.c:27:3: note: (2) when 'i < count' test.c:29:5: note: (3) when calling 'PyList_Append', passing NULL from (1) as argument 1 iinnlliinnee--eevveennttss means to print the events "inline" within the source code. This view attempts to consolidate the events into runs of sufficiently-close events, printing them as labelled ranges within the source. For example, the same events as above might be printed as: 'test': events 1-3 | | 25 | list = PyList_New(0); | | ^~~~~~~~~~~~~ | | | | | (1) when 'PyList_New' fails, returning NULL | 26 | | 27 | for (i = 0; i < count; i++) { | | ~~~ | | | | | (2) when 'i < count' | 28 | item = PyLong_FromLong(random()); | 29 | PyList_Append(list, item); | | ~~~~~~~~~~~~~~~~~~~~~~~~~ | | | | | (3) when calling 'PyList_Append', passing NULL from (1) as argument 1 | Interprocedural control flow is shown by grouping the events by stack frame, and using indentation to show how stack frames are nested, pushed, and popped. For example: 'test': events 1-2 | | 133 | { | | ^ | | | | | (1) entering 'test' | 134 | boxed_int *obj = make_boxed_int (i); | | ~~~~~~~~~~~~~~~~~~ | | | | | (2) calling 'make_boxed_int' | +--> 'make_boxed_int': events 3-4 | | 120 | { | | ^ | | | | | (3) entering 'make_boxed_int' | 121 | boxed_int *result = (boxed_int *)wrapped_malloc (sizeof (boxed_int)); | | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | | | | | (4) calling 'wrapped_malloc' | +--> 'wrapped_malloc': events 5-6 | | 7 | { | | ^ | | | | | (5) entering 'wrapped_malloc' | 8 | return malloc (size); | | ~~~~~~~~~~~~~ | | | | | (6) calling 'malloc' | <-------------+ | 'test': event 7 | | 138 | free_boxed_int (obj); | | ^~~~~~~~~~~~~~~~~~~~ | | | | | (7) calling 'free_boxed_int' | (etc) --ffddiiaaggnnoossttiiccss--sshhooww--ppaatthh--ddeepptthhss This option provides additional information when printing control- flow paths associated with a diagnostic. If this is option is provided then the stack depth will be printed for each run of events within --ffddiiaaggnnoossttiiccss--ppaatthh--ffoorrmmaatt==sseeppaa-- rraattee--eevveennttss. This is intended for use by GCC developers and plugin developers when debugging diagnostics that report interprocedural control flow. --ffnnoo--sshhooww--ccoolluummnn Do not print column numbers in diagnostics. This may be necessary if diagnostics are being scanned by a program that does not under- stand the column numbers, such as ddeejjaaggnnuu. --ffddiiaaggnnoossttiiccss--ccoolluummnn--uunniitt==_U_N_I_T Select the units for the column number. This affects traditional diagnostics (in the absence of --ffnnoo--sshhooww--ccoolluummnn), as well as JSON format diagnostics if requested. The default _U_N_I_T, ddiissppllaayy, considers the number of display columns occupied by each character. This may be larger than the number of bytes required to encode the character, in the case of tab charac- ters, or it may be smaller, in the case of multibyte characters. For example, the character "GREEK SMALL LETTER PI (U+03C0)" occu- pies one display column, and its UTF-8 encoding requires two bytes; the character "SLIGHTLY SMILING FACE (U+1F642)" occupies two dis- play columns, and its UTF-8 encoding requires four bytes. Setting _U_N_I_T to bbyyttee changes the column number to the raw byte count in all cases, as was traditionally output by GCC prior to version 11.1.0. --ffddiiaaggnnoossttiiccss--ccoolluummnn--oorriiggiinn==_O_R_I_G_I_N Select the origin for column numbers, i.e. the column number as- signed to the first column. The default value of 1 corresponds to traditional GCC behavior and to the GNU style guide. Some utili- ties may perform better with an origin of 0; any non-negative value may be specified. --ffddiiaaggnnoossttiiccss--eessccaappee--ffoorrmmaatt==_F_O_R_M_A_T When GCC prints pertinent source lines for a diagnostic it normally attempts to print the source bytes directly. However, some diag- nostics relate to encoding issues in the source file, such as mal- formed UTF-8, or issues with Unicode normalization. These diagnos- tics are flagged so that GCC will escape bytes that are not print- able ASCII when printing their pertinent source lines. This option controls how such bytes should be escaped. The default _F_O_R_M_A_T, uunniiccooddee displays Unicode characters that are not printable ASCII in the form <>, and bytes that do not correspond to a Unicode character validly-encoded in UTF-8-encoded will be displayed as hexadecimal in the form <>. For example, a source line containing the string bbeeffoorree followed by the Unicode character U+03C0 ("GREEK SMALL LETTER PI", with UTF-8 encoding 0xCF 0x80) followed by the byte 0xBF (a stray UTF-8 trail- ing byte), followed by the string aafftteerr will be printed for such a diagnostic as: beforeafter Setting _F_O_R_M_A_T to bbyytteess will display all non-printable-ASCII bytes in the form <>, thus showing the underlying encoding of non-ASCII Unicode characters. For the example above, the following will be printed: before<80>after --ffddiiaaggnnoossttiiccss--ffoorrmmaatt==_F_O_R_M_A_T Select a different format for printing diagnostics. _F_O_R_M_A_T is tteexxtt or jjssoonn. The default is tteexxtt. The jjssoonn format consists of a top-level JSON array containing JSON objects representing the diagnostics. The JSON is emitted as one line, without formatting; the examples below have been formatted for clarity. Diagnostics can have child diagnostics. For example, this error and note: misleading-indentation.c:15:3: warning: this 'if' clause does not guard... [-Wmisleading-indentation] 15 | if (flag) | ^~ misleading-indentation.c:17:5: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if' 17 | y = 2; | ^ might be printed in JSON form (after formatting) like this: [ { "kind": "warning", "locations": [ { "caret": { "display-column": 3, "byte-column": 3, "column": 3, "file": "misleading-indentation.c", "line": 15 }, "finish": { "display-column": 4, "byte-column": 4, "column": 4, "file": "misleading-indentation.c", "line": 15 } } ], "message": "this \u2018if\u2019 clause does not guard...", "option": "-Wmisleading-indentation", "option_url": "https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wmisleading-indentation", "children": [ { "kind": "note", "locations": [ { "caret": { "display-column": 5, "byte-column": 5, "column": 5, "file": "misleading-indentation.c", "line": 17 } } ], "escape-source": false, "message": "...this statement, but the latter is ..." } ] "escape-source": false, "column-origin": 1, } ] where the "note" is a child of the "warning". A diagnostic has a "kind". If this is "warning", then there is an "option" key describing the command-line option controlling the warning. A diagnostic can contain zero or more locations. Each location has an optional "label" string and up to three positions within it: a "caret" position and optional "start" and "finish" positions. A position is described by a "file" name, a "line" number, and three numbers indicating a column position: * "display-column" counts display columns, accounting for tabs and multibyte characters. * "byte-column" counts raw bytes. * "column" is equal to one of the previous two, as dictated by the --ffddiiaaggnnoossttiiccss--ccoolluummnn--uunniitt option. All three columns are relative to the origin specified by --ffddiiaagg-- nnoossttiiccss--ccoolluummnn--oorriiggiinn, which is typically equal to 1 but may be set, for instance, to 0 for compatibility with other utilities that number columns from 0. The column origin is recorded in the JSON output in the "column-origin" tag. In the remaining examples be- low, the extra column number outputs have been omitted for brevity. For example, this error: bad-binary-ops.c:64:23: error: invalid operands to binary + (have 'S' {aka 'struct s'} and 'T' {aka 'struct t'}) 64 | return callee_4a () + callee_4b (); | ~~~~~~~~~~~~ ^ ~~~~~~~~~~~~ | | | | | T {aka struct t} | S {aka struct s} has three locations. Its primary location is at the "+" token at column 23. It has two secondary locations, describing the left and right-hand sides of the expression, which have labels. It might be printed in JSON form as: { "children": [], "kind": "error", "locations": [ { "caret": { "column": 23, "file": "bad-binary-ops.c", "line": 64 } }, { "caret": { "column": 10, "file": "bad-binary-ops.c", "line": 64 }, "finish": { "column": 21, "file": "bad-binary-ops.c", "line": 64 }, "label": "S {aka struct s}" }, { "caret": { "column": 25, "file": "bad-binary-ops.c", "line": 64 }, "finish": { "column": 36, "file": "bad-binary-ops.c", "line": 64 }, "label": "T {aka struct t}" } ], "escape-source": false, "message": "invalid operands to binary + ..." } If a diagnostic contains fix-it hints, it has a "fixits" array, consisting of half-open intervals, similar to the output of --ffddiiaagg-- nnoossttiiccss--ppaarrsseeaabbllee--ffiixxiittss. For example, this diagnostic with a re- placement fix-it hint: demo.c:8:15: error: 'struct s' has no member named 'colour'; did you mean 'color'? 8 | return ptr->colour; | ^~~~~~ | color might be printed in JSON form as: { "children": [], "fixits": [ { "next": { "column": 21, "file": "demo.c", "line": 8 }, "start": { "column": 15, "file": "demo.c", "line": 8 }, "string": "color" } ], "kind": "error", "locations": [ { "caret": { "column": 15, "file": "demo.c", "line": 8 }, "finish": { "column": 20, "file": "demo.c", "line": 8 } } ], "escape-source": false, "message": "\u2018struct s\u2019 has no member named ..." } where the fix-it hint suggests replacing the text from "start" up to but not including "next" with "string"'s value. Deletions are expressed via an empty value for "string", insertions by having "start" equal "next". If the diagnostic has a path of control-flow events associated with it, it has a "path" array of objects representing the events. Each event object has a "description" string, a "location" object, along with a "function" string and a "depth" number for representing in- terprocedural paths. The "function" represents the current func- tion at that event, and the "depth" represents the stack depth rel- ative to some baseline: the higher, the more frames are within the stack. For example, the intraprocedural example shown for --ffddiiaaggnnooss-- ttiiccss--ppaatthh--ffoorrmmaatt== might have this JSON for its path: "path": [ { "depth": 0, "description": "when 'PyList_New' fails, returning NULL", "function": "test", "location": { "column": 10, "file": "test.c", "line": 25 } }, { "depth": 0, "description": "when 'i < count'", "function": "test", "location": { "column": 3, "file": "test.c", "line": 27 } }, { "depth": 0, "description": "when calling 'PyList_Append', passing NULL from (1) as argument 1", "function": "test", "location": { "column": 5, "file": "test.c", "line": 29 } } ] Diagnostics have a boolean attribute "escape-source", hinting whether non-ASCII bytes should be escaped when printing the perti- nent lines of source code ("true" for diagnostics involving source encoding issues). OOppttiioonnss ttoo RReeqquueesstt oorr SSuupppprreessss WWaarrnniinnggss Warnings are diagnostic messages that report constructions that are not inherently erroneous but that are risky or suggest there may have been an error. The following language-independent options do not enable specific warn- ings but control the kinds of diagnostics produced by GCC. --ffssyynnttaaxx--oonnllyy Check the code for syntax errors, but don't do anything beyond that. --ffmmaaxx--eerrrroorrss==_n Limits the maximum number of error messages to _n, at which point GCC bails out rather than attempting to continue processing the source code. If _n is 0 (the default), there is no limit on the number of error messages produced. If --WWffaattaall--eerrrroorrss is also spec- ified, then --WWffaattaall--eerrrroorrss takes precedence over this option. --ww Inhibit all warning messages. --WWeerrrroorr Make all warnings into errors. --WWeerrrroorr== Make the specified warning into an error. The specifier for a warning is appended; for example --WWeerrrroorr==sswwiittcchh turns the warnings controlled by --WWsswwiittcchh into errors. This switch takes a negative form, to be used to negate --WWeerrrroorr for specific warnings; for exam- ple --WWnnoo--eerrrroorr==sswwiittcchh makes --WWsswwiittcchh warnings not be errors, even when --WWeerrrroorr is in effect. The warning message for each controllable warning includes the op- tion that controls the warning. That option can then be used with --WWeerrrroorr== and --WWnnoo--eerrrroorr== as described above. (Printing of the op- tion in the warning message can be disabled using the --ffnnoo--ddiiaaggnnooss-- ttiiccss--sshhooww--ooppttiioonn flag.) Note that specifying --WWeerrrroorr==_f_o_o automatically implies --WW_f_o_o. How- ever, --WWnnoo--eerrrroorr==_f_o_o does not imply anything. --WWffaattaall--eerrrroorrss This option causes the compiler to abort compilation on the first error occurred rather than trying to keep going and printing fur- ther error messages. You can request many specific warnings with options beginning with --WW, for example --WWiimmpplliicciitt to request warnings on implicit declarations. Each of these specific warning options also has a negative form begin- ning --WWnnoo-- to turn off warnings; for example, --WWnnoo--iimmpplliicciitt. This man- ual lists only one of the two forms, whichever is not the default. For further language-specific options also refer to CC++++ DDiiaalleecctt OOppttiioonnss and OObbjjeeccttiivvee--CC aanndd OObbjjeeccttiivvee--CC++++ DDiiaalleecctt OOppttiioonnss. Additional warnings can be produced by enabling the static analyzer; Some options, such as --WWaallll and --WWeexxttrraa, turn on other options, such as --WWuunnuusseedd, which may turn on further options, such as --WWuunnuusseedd--vvaalluuee. The combined effect of positive and negative forms is that more spe- cific options have priority over less specific ones, independently of their position in the command-line. For options of the same speci- ficity, the last one takes effect. Options enabled or disabled via pragmas take effect as if they appeared at the end of the command-line. When an unrecognized warning option is requested (e.g., --WWuunnkknnoowwnn--wwaarrnn-- iinngg), GCC emits a diagnostic stating that the option is not recognized. However, if the --WWnnoo-- form is used, the behavior is slightly different: no diagnostic is produced for --WWnnoo--uunnkknnoowwnn--wwaarrnniinngg unless other diag- nostics are being produced. This allows the use of new --WWnnoo-- options with old compilers, but if something goes wrong, the compiler warns that an unrecognized option is present. The effectiveness of some warnings depends on optimizations also being enabled. For example --WWssuuggggeesstt--ffiinnaall--ttyyppeess is more effective with link- time optimization and some instances of other warnings may not be is- sued at all unless optimization is enabled. While optimization in gen- eral improves the efficacy of control and data flow sensitive warnings, in some cases it may also cause false positives. --WWppeeddaannttiicc --ppeeddaannttiicc Issue all the warnings demanded by strict ISO C and ISO C++; reject all programs that use forbidden extensions, and some other programs that do not follow ISO C and ISO C++. For ISO C, follows the ver- sion of the ISO C standard specified by any --ssttdd option used. Valid ISO C and ISO C++ programs should compile properly with or without this option (though a rare few require --aannssii or a --ssttdd op- tion specifying the required version of ISO C). However, without this option, certain GNU extensions and traditional C and C++ fea- tures are supported as well. With this option, they are rejected. --WWppeeddaannttiicc does not cause warning messages for use of the alternate keywords whose names begin and end with ____. This alternate format can also be used to disable warnings for non-ISO ____iinnttNN types, i.e. ____iinnttNN____. Pedantic warnings are also disabled in the expression that follows "__extension__". However, only system header files should use these escape routes; application programs should avoid them. Some users try to use --WWppeeddaannttiicc to check programs for strict ISO C conformance. They soon find that it does not do quite what they want: it finds some non-ISO practices, but not all---only those for which ISO C _r_e_q_u_i_r_e_s a diagnostic, and some others for which diag- nostics have been added. A feature to report any failure to conform to ISO C might be useful in some instances, but would require considerable additional work and would be quite different from --WWppeeddaannttiicc. We don't have plans to support such a feature in the near future. Where the standard specified with --ssttdd represents a GNU extended dialect of C, such as ggnnuu9900 or ggnnuu9999, there is a corresponding _b_a_s_e _s_t_a_n_d_a_r_d, the version of ISO C on which the GNU extended dialect is based. Warnings from --WWppeeddaannttiicc are given where they are required by the base standard. (It does not make sense for such warnings to be given only for features not in the specified GNU C dialect, since by definition the GNU dialects of C include all features the compiler supports with the given option, and there would be nothing to warn about.) --ppeeddaannttiicc--eerrrroorrss Give an error whenever the _b_a_s_e _s_t_a_n_d_a_r_d (see --WWppeeddaannttiicc) requires a diagnostic, in some cases where there is undefined behavior at compile-time and in some other cases that do not prevent compila- tion of programs that are valid according to the standard. This is not equivalent to --WWeerrrroorr==ppeeddaannttiicc, since there are errors enabled by this option and not enabled by the latter and vice versa. --WWaallll This enables all the warnings about constructions that some users consider questionable, and that are easy to avoid (or modify to prevent the warning), even in conjunction with macros. This also enables some language-specific warnings described in CC++++ DDiiaalleecctt OOppttiioonnss and OObbjjeeccttiivvee--CC aanndd OObbjjeeccttiivvee--CC++++ DDiiaalleecctt OOppttiioonnss. --WWaallll turns on the following warning flags: --WWaaddddrreessss --WWaarrrraayy--bboouunnddss==11 (only with --OO22) --WWaarrrraayy--ccoommppaarree --WWaarr-- rraayy--ppaarraammeetteerr==22 (C and Objective-C only) --WWbbooooll--ccoommppaarree --WWbbooooll--oopp-- eerraattiioonn --WWcc++++1111--ccoommppaatt --WWcc++++1144--ccoommppaatt --WWccaattcchh--vvaalluuee (C++ and Ob- jective-C++ only) --WWcchhaarr--ssuubbssccrriippttss --WWccoommmmeenntt --WWddaanngglliinngg--ppooiinntteerr==22 --WWdduupplliiccaattee--ddeeccll--ssppeecciiffiieerr (C and Objective-C only) --WWeennuumm--ccoommppaarree (in C/ObjC; this is on by default in C++) --WWffoorrmmaatt --WWffoorrmmaatt--oovveerr-- ffllooww --WWffoorrmmaatt--ttrruunnccaattiioonn --WWiinntt--iinn--bbooooll--ccoonntteexxtt --WWiimmpplliicciitt (C and Objective-C only) --WWiimmpplliicciitt--iinntt (C and Objective-C only) --WWiimm-- pplliicciitt--ffuunnccttiioonn--ddeeccllaarraattiioonn (C and Objective-C only) --WWiinniitt--sseellff (only for C++) --WWllooggiiccaall--nnoott--ppaarreenntthheesseess --WWmmaaiinn (only for C/ObjC and unless --ffffrreeeessttaannddiinngg) --WWmmaayybbee--uunniinniittiiaalliizzeedd --WWmmeemmsseett--eelltt--ssiizzee --WWmmeemmsseett--ttrraannssppoosseedd--aarrggss --WWmmiisslleeaaddiinngg--iinnddeennttaattiioonn (only for C/C++) --WWmmiissmmaattcchheedd--ddeeaalllloocc --WWmmiissmmaattcchheedd--nneeww--ddeelleettee (only for C/C++) --WWmmiissssiinngg--aattttrriibbuutteess --WWmmiissssiinngg--bbrraacceess (only for C/ObjC) --WWmmuullttii-- ssttaatteemmeenntt--mmaaccrrooss --WWnnaarrrroowwiinngg (only for C++) --WWnnoonnnnuullll --WWnnoonn-- nnuullll--ccoommppaarree --WWooppeennmmpp--ssiimmdd --WWppaarreenntthheesseess --WWppeessssiimmiizziinngg--mmoovvee (only for C++) --WWppooiinntteerr--ssiiggnn --WWrraannggee--lloooopp--ccoonnssttrruucctt (only for C++) --WWrree-- oorrddeerr --WWrreessttrriicctt --WWrreettuurrnn--ttyyppee --WWsseeqquueennccee--ppooiinntt --WWssiiggnn--ccoommppaarree (only in C++) --WWssiizzeeooff--aarrrraayy--ddiivv --WWssiizzeeooff--ppooiinntteerr--ddiivv --WWssiizzeeooff--ppooiinntteerr--mmeemmaacccceessss --WWssttrriicctt--aalliiaassiinngg --WWssttrriicctt--oovveerrffllooww==11 --WWsswwiittcchh --WWttaauuttoollooggiiccaall--ccoommppaarree --WWttrriiggrraapphhss --WWuunniinniittiiaalliizzeedd --WWuunn-- kknnoowwnn--pprraaggmmaass --WWuunnuusseedd--ffuunnccttiioonn --WWuunnuusseedd--llaabbeell --WWuunnuusseedd--vvaalluuee --WWuunnuusseedd--vvaarriiaabbllee --WWuussee--aafftteerr--ffrreeee==33 --WWvvllaa--ppaarraammeetteerr (C and Objec- tive-C only) --WWvvoollaattiillee--rreeggiisstteerr--vvaarr --WWzzeerroo--lleennggtthh--bboouunnddss Note that some warning flags are not implied by --WWaallll. Some of them warn about constructions that users generally do not consider questionable, but which occasionally you might wish to check for; others warn about constructions that are necessary or hard to avoid in some cases, and there is no simple way to modify the code to suppress the warning. Some of them are enabled by --WWeexxttrraa but many of them must be enabled individually. --WWeexxttrraa This enables some extra warning flags that are not enabled by --WWaallll. (This option used to be called --WW. The older name is still supported, but the newer name is more descriptive.) --WWcclloobbbbeerreedd --WWccaasstt--ffuunnccttiioonn--ttyyppee --WWddeepprreeccaatteedd--ccooppyy (C++ only) --WWeemmppttyy--bbooddyy --WWeennuumm--ccoonnvveerrssiioonn (C only) --WWiiggnnoorreedd--qquuaalliiffiieerrss --WWiimm-- pplliicciitt--ffaalllltthhrroouugghh==33 --WWmmiissssiinngg--ffiieelldd--iinniittiiaalliizzeerrss --WWmmiissssiinngg--ppaarraammee-- tteerr--ttyyppee (C only) --WWoolldd--ssttyyllee--ddeeccllaarraattiioonn (C only) --WWoovveerrrriiddee--iinniitt --WWssiiggnn--ccoommppaarree (C only) --WWssttrriinngg--ccoommppaarree --WWrreedduunnddaanntt--mmoovvee (only for C++) --WWttyyppee--lliimmiittss --WWuunniinniittiiaalliizzeedd --WWsshhiifftt--nneeggaattiivvee--vvaalluuee (in C++11 to C++17 and in C99 and newer) --WWuunnuusseedd--ppaarraammeetteerr (only with --WWuunnuusseedd or --WWaallll) --WWuunnuusseedd--bbuutt--sseett--ppaarraammeetteerr (only with --WWuunnuusseedd or --WWaallll) The option --WWeexxttrraa also prints warning messages for the following cases: * A pointer is compared against integer zero with "<", "<=", ">", or ">=". * (C++ only) An enumerator and a non-enumerator both appear in a conditional expression. * (C++ only) Ambiguous virtual bases. * (C++ only) Subscripting an array that has been declared "regis- ter". * (C++ only) Taking the address of a variable that has been de- clared "register". * (C++ only) A base class is not initialized in the copy con- structor of a derived class. --WWaabbii (C, Objective-C, C++ and Objective-C++ only) Warn about code affected by ABI changes. This includes code that may not be compatible with the vendor-neutral C++ ABI as well as the psABI for the particular target. Since G++ now defaults to updating the ABI with each major release, normally --WWaabbii warns only about C++ ABI compatibility problems if there is a check added later in a release series for an ABI issue discovered since the initial release. --WWaabbii warns about more things if an older ABI version is selected (with --ffaabbii--vveerrssiioonn==_n). --WWaabbii can also be used with an explicit version number to warn about C++ ABI compatibility with a particular --ffaabbii--vveerrssiioonn level, e.g. --WWaabbii==22 to warn about changes relative to --ffaabbii--vveerrssiioonn==22. If an explicit version number is provided and --ffaabbii--ccoommppaatt--vveerrssiioonn is not specified, the version number from this option is used for compatibility aliases. If no explicit version number is provided with this option, but --ffaabbii--ccoommppaatt--vveerrssiioonn is specified, that ver- sion number is used for C++ ABI warnings. Although an effort has been made to warn about all such cases, there are probably some cases that are not warned about, even though G++ is generating incompatible code. There may also be cases where warnings are emitted even though the code that is gen- erated is compatible. You should rewrite your code to avoid these warnings if you are concerned about the fact that code generated by G++ may not be bi- nary compatible with code generated by other compilers. Known incompatibilities in --ffaabbii--vveerrssiioonn==22 (which was the default from GCC 3.4 to 4.9) include: * A template with a non-type template parameter of reference type was mangled incorrectly: extern int N; template struct S {}; void n (S) {2} This was fixed in --ffaabbii--vveerrssiioonn==33. * SIMD vector types declared using "__attribute ((vector_size))" were mangled in a non-standard way that does not allow for overloading of functions taking vectors of different sizes. The mangling was changed in --ffaabbii--vveerrssiioonn==44. * "__attribute ((const))" and "noreturn" were mangled as type qualifiers, and "decltype" of a plain declaration was folded away. These mangling issues were fixed in --ffaabbii--vveerrssiioonn==55. * Scoped enumerators passed as arguments to a variadic function are promoted like unscoped enumerators, causing "va_arg" to complain. On most targets this does not actually affect the parameter passing ABI, as there is no way to pass an argument smaller than "int". Also, the ABI changed the mangling of template argument packs, "const_cast", "static_cast", prefix increment/decrement, and a class scope function used as a template argument. These issues were corrected in --ffaabbii--vveerrssiioonn==66. * Lambdas in default argument scope were mangled incorrectly, and the ABI changed the mangling of "nullptr_t". These issues were corrected in --ffaabbii--vveerrssiioonn==77. * When mangling a function type with function-cv-qualifiers, the un-qualified function type was incorrectly treated as a substi- tution candidate. This was fixed in --ffaabbii--vveerrssiioonn==88, the default for GCC 5.1. * "decltype(nullptr)" incorrectly had an alignment of 1, leading to unaligned accesses. Note that this did not affect the ABI of a function with a "nullptr_t" parameter, as parameters have a minimum alignment. This was fixed in --ffaabbii--vveerrssiioonn==99, the default for GCC 5.2. * Target-specific attributes that affect the identity of a type, such as ia32 calling conventions on a function type (stdcall, regparm, etc.), did not affect the mangled name, leading to name collisions when function pointers were used as template arguments. This was fixed in --ffaabbii--vveerrssiioonn==1100, the default for GCC 6.1. This option also enables warnings about psABI-related changes. The known psABI changes at this point include: * For SysV/x86-64, unions with "long double" members are passed in memory as specified in psABI. Prior to GCC 4.4, this was not the case. For example: union U { long double ld; int i; }; "union U" is now always passed in memory. --WWcchhaarr--ssuubbssccrriippttss Warn if an array subscript has type "char". This is a common cause of error, as programmers often forget that this type is signed on some machines. This warning is enabled by --WWaallll. --WWnnoo--ccoovveerraaggee--mmiissmmaattcchh Warn if feedback profiles do not match when using the --ffpprrooffiillee--uussee option. If a source file is changed between compiling with --ffpprroo-- ffiillee--ggeenneerraattee and with --ffpprrooffiillee--uussee, the files with the profile feedback can fail to match the source file and GCC cannot use the profile feedback information. By default, this warning is enabled and is treated as an error. --WWnnoo--ccoovveerraaggee--mmiissmmaattcchh can be used to disable the warning or --WWnnoo--eerrrroorr==ccoovveerraaggee--mmiissmmaattcchh can be used to disable the error. Disabling the error for this warning can result in poorly optimized code and is useful only in the case of very mi- nor changes such as bug fixes to an existing code-base. Completely disabling the warning is not recommended. --WWnnoo--ccoovveerraaggee--iinnvvaalliidd--lliinnee--nnuummbbeerr Warn in case a function ends earlier than it begins due to an in- valid linenum macros. The warning is emitted only with ----ccoovveerraaggee enabled. By default, this warning is enabled and is treated as an error. --WWnnoo--ccoovveerraaggee--iinnvvaalliidd--lliinnee--nnuummbbeerr can be used to disable the warn- ing or --WWnnoo--eerrrroorr==ccoovveerraaggee--iinnvvaalliidd--lliinnee--nnuummbbeerr can be used to dis- able the error. --WWnnoo--ccpppp (C, Objective-C, C++, Objective-C++ and Fortran only) Suppress warning messages emitted by "#warning" directives. --WWddoouubbllee--pprroommoottiioonn (C, C++, Objective-C and Objective-C++ only) Give a warning when a value of type "float" is implicitly promoted to "double". CPUs with a 32-bit "single-precision" floating-point unit implement "float" in hardware, but emulate "double" in soft- ware. On such a machine, doing computations using "double" values is much more expensive because of the overhead required for soft- ware emulation. It is easy to accidentally do computations with "double" because floating-point literals are implicitly of type "double". For exam- ple, in: float area(float radius) { return 3.14159 * radius * radius; } the compiler performs the entire computation with "double" because the floating-point literal is a "double". --WWdduupplliiccaattee--ddeeccll--ssppeecciiffiieerr (C and Objective-C only) Warn if a declaration has duplicate "const", "volatile", "restrict" or "_Atomic" specifier. This warning is enabled by --WWaallll. --WWffoorrmmaatt --WWffoorrmmaatt==_n Check calls to "printf" and "scanf", etc., to make sure that the arguments supplied have types appropriate to the format string specified, and that the conversions specified in the format string make sense. This includes standard functions, and others specified by format attributes, in the "printf", "scanf", "strftime" and "strfmon" (an X/Open extension, not in the C standard) families (or other target-specific families). Which functions are checked with- out format attributes having been specified depends on the standard version selected, and such checks of functions without the attri- bute specified are disabled by --ffffrreeeessttaannddiinngg or --ffnnoo--bbuuiillttiinn. The formats are checked against the format features supported by GNU libc version 2.2. These include all ISO C90 and C99 features, as well as features from the Single Unix Specification and some BSD and GNU extensions. Other library implementations may not support all these features; GCC does not support warning about features that go beyond a particular library's limitations. However, if --WWppeeddaannttiicc is used with --WWffoorrmmaatt, warnings are given about format features not in the selected standard version (but not for "strf- mon" formats, since those are not in any version of the C stan- dard). --WWffoorrmmaatt==11 --WWffoorrmmaatt Option --WWffoorrmmaatt is equivalent to --WWffoorrmmaatt==11, and --WWnnoo--ffoorrmmaatt is equivalent to --WWffoorrmmaatt==00. Since --WWffoorrmmaatt also checks for null format arguments for several functions, --WWffoorrmmaatt also implies --WWnnoonnnnuullll. Some aspects of this level of format checking can be disabled by the options: --WWnnoo--ffoorrmmaatt--ccoonnttaaiinnss--nnuull, --WWnnoo--ffoorr-- mmaatt--eexxttrraa--aarrggss, and --WWnnoo--ffoorrmmaatt--zzeerroo--lleennggtthh. --WWffoorrmmaatt is en- abled by --WWaallll. --WWffoorrmmaatt==22 Enable --WWffoorrmmaatt plus additional format checks. Currently equivalent to --WWffoorrmmaatt --WWffoorrmmaatt--nnoonnlliitteerraall --WWffoorrmmaatt--sseeccuurriittyy --WWffoorrmmaatt--yy22kk. --WWnnoo--ffoorrmmaatt--ccoonnttaaiinnss--nnuull If --WWffoorrmmaatt is specified, do not warn about format strings that contain NUL bytes. --WWnnoo--ffoorrmmaatt--eexxttrraa--aarrggss If --WWffoorrmmaatt is specified, do not warn about excess arguments to a "printf" or "scanf" format function. The C standard specifies that such arguments are ignored. Where the unused arguments lie between used arguments that are specified with $$ operand number specifications, normally warnings are still given, since the implementation could not know what type to pass to "va_arg" to skip the unused arguments. However, in the case of "scanf" formats, this option suppresses the warning if the unused arguments are all pointers, since the Single Unix Specifica- tion says that such unused arguments are allowed. --WWffoorrmmaatt--oovveerrffllooww --WWffoorrmmaatt--oovveerrffllooww==_l_e_v_e_l Warn about calls to formatted input/output functions such as "sprintf" and "vsprintf" that might overflow the destination buf- fer. When the exact number of bytes written by a format directive cannot be determined at compile-time it is estimated based on heuristics that depend on the _l_e_v_e_l argument and on optimization. While enabling optimization will in most cases improve the accuracy of the warning, it may also result in false positives. --WWffoorrmmaatt--oovveerrffllooww --WWffoorrmmaatt--oovveerrffllooww==11 Level _1 of --WWffoorrmmaatt--oovveerrffllooww enabled by --WWffoorrmmaatt employs a con- servative approach that warns only about calls that most likely overflow the buffer. At this level, numeric arguments to for- mat directives with unknown values are assumed to have the value of one, and strings of unknown length to be empty. Nu- meric arguments that are known to be bounded to a subrange of their type, or string arguments whose output is bounded either by their directive's precision or by a finite set of string literals, are assumed to take on the value within the range that results in the most bytes on output. For example, the call to "sprintf" below is diagnosed because even with both _a and _b equal to zero, the terminating NUL character ('\0') ap- pended by the function to the destination buffer will be writ- ten past its end. Increasing the size of the buffer by a sin- gle byte is sufficient to avoid the warning, though it may not be sufficient to avoid the overflow. void f (int a, int b) { char buf [13]; sprintf (buf, "a = %i, b = %i\n", a, b); } --WWffoorrmmaatt--oovveerrffllooww==22 Level _2 warns also about calls that might overflow the destina- tion buffer given an argument of sufficient length or magni- tude. At level _2, unknown numeric arguments are assumed to have the minimum representable value for signed types with a precision greater than 1, and the maximum representable value otherwise. Unknown string arguments whose length cannot be as- sumed to be bounded either by the directive's precision, or by a finite set of string literals they may evaluate to, or the character array they may point to, are assumed to be 1 charac- ter long. At level _2, the call in the example above is again diagnosed, but this time because with _a equal to a 32-bit "INT_MIN" the first %i directive will write some of its digits beyond the end of the destination buffer. To make the call safe regardless of the values of the two variables, the size of the destination buffer must be increased to at least 34 bytes. GCC includes the minimum size of the buffer in an informational note follow- ing the warning. An alternative to increasing the size of the destination buffer is to constrain the range of formatted values. The maximum length of string arguments can be bounded by specifying the precision in the format directive. When numeric arguments of format directives can be assumed to be bounded by less than the precision of their type, choosing an appropriate length modi- fier to the format specifier will reduce the required buffer size. For example, if _a and _b in the example above can be as- sumed to be within the precision of the "short int" type then using either the %hi format directive or casting the argument to "short" reduces the maximum required size of the buffer to 24 bytes. void f (int a, int b) { char buf [23]; sprintf (buf, "a = %hi, b = %i\n", a, (short)b); } --WWnnoo--ffoorrmmaatt--zzeerroo--lleennggtthh If --WWffoorrmmaatt is specified, do not warn about zero-length formats. The C standard specifies that zero-length formats are allowed. --WWffoorrmmaatt--nnoonnlliitteerraall If --WWffoorrmmaatt is specified, also warn if the format string is not a string literal and so cannot be checked, unless the format function takes its format arguments as a "va_list". --WWffoorrmmaatt--sseeccuurriittyy If --WWffoorrmmaatt is specified, also warn about uses of format functions that represent possible security problems. At present, this warns about calls to "printf" and "scanf" functions where the format string is not a string literal and there are no format arguments, as in "printf (foo);". This may be a security hole if the format string came from untrusted input and contains %%nn. (This is cur- rently a subset of what --WWffoorrmmaatt--nnoonnlliitteerraall warns about, but in fu- ture warnings may be added to --WWffoorrmmaatt--sseeccuurriittyy that are not in- cluded in --WWffoorrmmaatt--nnoonnlliitteerraall.) --WWffoorrmmaatt--ssiiggnneeddnneessss If --WWffoorrmmaatt is specified, also warn if the format string requires an unsigned argument and the argument is signed and vice versa. --WWffoorrmmaatt--ttrruunnccaattiioonn --WWffoorrmmaatt--ttrruunnccaattiioonn==_l_e_v_e_l Warn about calls to formatted input/output functions such as "snprintf" and "vsnprintf" that might result in output truncation. When the exact number of bytes written by a format directive cannot be determined at compile-time it is estimated based on heuristics that depend on the _l_e_v_e_l argument and on optimization. While en- abling optimization will in most cases improve the accuracy of the warning, it may also result in false positives. Except as noted otherwise, the option uses the same logic --WWffoorrmmaatt--oovveerrffllooww. --WWffoorrmmaatt--ttrruunnccaattiioonn --WWffoorrmmaatt--ttrruunnccaattiioonn==11 Level _1 of --WWffoorrmmaatt--ttrruunnccaattiioonn enabled by --WWffoorrmmaatt employs a conservative approach that warns only about calls to bounded functions whose return value is unused and that will most likely result in output truncation. --WWffoorrmmaatt--ttrruunnccaattiioonn==22 Level _2 warns also about calls to bounded functions whose re- turn value is used and that might result in truncation given an argument of sufficient length or magnitude. --WWffoorrmmaatt--yy22kk If --WWffoorrmmaatt is specified, also warn about "strftime" formats that may yield only a two-digit year. --WWnnoonnnnuullll Warn about passing a null pointer for arguments marked as requiring a non-null value by the "nonnull" function attribute. --WWnnoonnnnuullll is included in --WWaallll and --WWffoorrmmaatt. It can be disabled with the --WWnnoo--nnoonnnnuullll option. --WWnnoonnnnuullll--ccoommppaarree Warn when comparing an argument marked with the "nonnull" function attribute against null inside the function. --WWnnoonnnnuullll--ccoommppaarree is included in --WWaallll. It can be disabled with the --WWnnoo--nnoonnnnuullll--ccoommppaarree option. --WWnnuullll--ddeerreeffeerreennccee Warn if the compiler detects paths that trigger erroneous or unde- fined behavior due to dereferencing a null pointer. This option is only active when --ffddeelleettee--nnuullll--ppooiinntteerr--cchheecckkss is active, which is enabled by optimizations in most targets. The precision of the warnings depends on the optimization options used. --WWiinnffiinniittee--rreeccuurrssiioonn Warn about infinitely recursive calls. The warning is effective at all optimization levels but requires optimization in order to de- tect infinite recursion in calls between two or more functions. --WWiinnffiinniittee--rreeccuurrssiioonn is included in --WWaallll. --WWiinniitt--sseellff (C, C++, Objective-C and Objective-C++ only) Warn about uninitialized variables that are initialized with them- selves. Note this option can only be used with the --WWuunniinniittiiaalliizzeedd option. For example, GCC warns about "i" being uninitialized in the follow- ing snippet only when --WWiinniitt--sseellff has been specified: int f() { int i = i; return i; } This warning is enabled by --WWaallll in C++. --WWnnoo--iimmpplliicciitt--iinntt (C and Objective-C only) This option controls warnings when a declaration does not specify a type. This warning is enabled by default in C99 and later dialects of C, and also by --WWaallll. --WWnnoo--iimmpplliicciitt--ffuunnccttiioonn--ddeeccllaarraattiioonn (C and Objective-C only) This option controls warnings when a function is used before being declared. This warning is enabled by default in C99 and later di- alects of C, and also by --WWaallll. The warning is made into an error by --ppeeddaannttiicc--eerrrroorrss. --WWiimmpplliicciitt (C and Objective-C only) Same as --WWiimmpplliicciitt--iinntt and --WWiimmpplliicciitt--ffuunnccttiioonn--ddeeccllaarraattiioonn. This warning is enabled by --WWaallll. --WWiimmpplliicciitt--ffaalllltthhrroouugghh --WWiimmpplliicciitt--ffaalllltthhrroouugghh is the same as --WWiimmpplliicciitt--ffaalllltthhrroouugghh==33 and --WWnnoo--iimmpplliicciitt--ffaalllltthhrroouugghh is the same as --WWiimmpplliicciitt--ffaalllltthhrroouugghh==00. --WWiimmpplliicciitt--ffaalllltthhrroouugghh==_n Warn when a switch case falls through. For example: switch (cond) { case 1: a = 1; break; case 2: a = 2; case 3: a = 3; break; } This warning does not warn when the last statement of a case cannot fall through, e.g. when there is a return statement or a call to function declared with the noreturn attribute. --WWiimm-- pplliicciitt--ffaalllltthhrroouugghh== also takes into account control flow state- ments, such as ifs, and only warns when appropriate. E.g. switch (cond) { case 1: if (i > 3) { bar (5); break; } else if (i < 1) { bar (0); } else return; default: ... } Since there are occasions where a switch case fall through is de- sirable, GCC provides an attribute, "__attribute__ ((fallthrough))", that is to be used along with a null statement to suppress this warning that would normally occur: switch (cond) { case 1: bar (0); __attribute__ ((fallthrough)); default: ... } C++17 provides a standard way to suppress the --WWiimm-- pplliicciitt--ffaalllltthhrroouugghh warning using "[[fallthrough]];" instead of the GNU attribute. In C++11 or C++14 users can use "[[gnu::fallthrough]];", which is a GNU extension. Instead of these attributes, it is also possible to add a fallthrough comment to silence the warning. The whole body of the C or C++ style com- ment should match the given regular expressions listed below. The option argument _n specifies what kind of comments are accepted: *<--WWiimmpplliicciitt--ffaalllltthhrroouugghh==00 disables the warning altogether.> *<--WWiimmpplliicciitt--ffaalllltthhrroouugghh==11 matches ".*" regular> expression, any comment is used as fallthrough comment. *<--WWiimmpplliicciitt--ffaalllltthhrroouugghh==22 case insensitively matches> ".*falls?[ \t-]*thr(ough|u).*" regular expression. *<--WWiimmpplliicciitt--ffaalllltthhrroouugghh==33 case sensitively matches one of the> following regular expressions: *<"-fallthrough"> *<"@fallthrough@"> *<"lint -fallthrough[ \t]*"> *<"[ \t.!]*(ELSE,? |INTENTIONAL(LY)? )?FALL(S | |-)?THR(OUGH|U)[ \t.!]*(-[^\n\r]*)?"> *<"[ \t.!]*(Else,? |Intentional(ly)? )?Fall((s | |-)[Tt]|t)hr(ough|u)[ \t.!]*(-[^\n\r]*)?"> *<"[ \t.!]*([Ee]lse,? |[Ii]ntentional(ly)? )?fall(s | |-)?thr(ough|u)[ \t.!]*(-[^\n\r]*)?"> *<--WWiimmpplliicciitt--ffaalllltthhrroouugghh==44 case sensitively matches one of the> following regular expressions: *<"-fallthrough"> *<"@fallthrough@"> *<"lint -fallthrough[ \t]*"> *<"[ \t]*FALLTHR(OUGH|U)[ \t]*"> *<--WWiimmpplliicciitt--ffaalllltthhrroouugghh==55 doesn't recognize any comments as> fallthrough comments, only attributes disable the warning. The comment needs to be followed after optional whitespace and other comments by "case" or "default" keywords or by a user label that precedes some "case" or "default" label. switch (cond) { case 1: bar (0); /* FALLTHRU */ default: ... } The --WWiimmpplliicciitt--ffaalllltthhrroouugghh==33 warning is enabled by --WWeexxttrraa. --WWnnoo--iiff--nnoott--aalliiggnneedd (C, C++, Objective-C and Objective-C++ only) Control if warnings triggered by the "warn_if_not_aligned" attri- bute should be issued. These warnings are enabled by default. --WWiiggnnoorreedd--qquuaalliiffiieerrss (C and C++ only) Warn if the return type of a function has a type qualifier such as "const". For ISO C such a type qualifier has no effect, since the value returned by a function is not an lvalue. For C++, the warn- ing is only emitted for scalar types or "void". ISO C prohibits qualified "void" return types on function definitions, so such re- turn types always receive a warning even without this option. This warning is also enabled by --WWeexxttrraa. --WWnnoo--iiggnnoorreedd--aattttrriibbuutteess (C and C++ only) This option controls warnings when an attribute is ignored. This is different from the --WWaattttrriibbuutteess option in that it warns whenever the compiler decides to drop an attribute, not that the attribute is either unknown, used in a wrong place, etc. This warning is en- abled by default. --WWmmaaiinn Warn if the type of "main" is suspicious. "main" should be a func- tion with external linkage, returning int, taking either zero argu- ments, two, or three arguments of appropriate types. This warning is enabled by default in C++ and is enabled by either --WWaallll or --WWppeeddaannttiicc. --WWmmiisslleeaaddiinngg--iinnddeennttaattiioonn (C and C++ only) Warn when the indentation of the code does not reflect the block structure. Specifically, a warning is issued for "if", "else", "while", and "for" clauses with a guarded statement that does not use braces, followed by an unguarded statement with the same inden- tation. In the following example, the call to "bar" is misleadingly in- dented as if it were guarded by the "if" conditional. if (some_condition ()) foo (); bar (); /* Gotcha: this is not guarded by the "if". */ In the case of mixed tabs and spaces, the warning uses the --ffttaabb-- ssttoopp== option to determine if the statements line up (defaulting to 8). The warning is not issued for code involving multiline preprocessor logic such as the following example. if (flagA) foo (0); #if SOME_CONDITION_THAT_DOES_NOT_HOLD if (flagB) #endif foo (1); The warning is not issued after a "#line" directive, since this typically indicates autogenerated code, and no assumptions can be made about the layout of the file that the directive references. This warning is enabled by --WWaallll in C and C++. --WWmmiissssiinngg--aattttrriibbuutteess Warn when a declaration of a function is missing one or more at- tributes that a related function is declared with and whose absence may adversely affect the correctness or efficiency of generated code. For example, the warning is issued for declarations of aliases that use attributes to specify less restrictive require- ments than those of their targets. This typically represents a po- tential optimization opportunity. By contrast, the --WWaatt-- ttrriibbuuttee--aalliiaass==22 option controls warnings issued when the alias is more restrictive than the target, which could lead to incorrect code generation. Attributes considered include "alloc_align", "al- loc_size", "cold", "const", "hot", "leaf", "malloc", "nonnull", "noreturn", "nothrow", "pure", "returns_nonnull", and "re- turns_twice". In C++, the warning is issued when an explicit specialization of a primary template declared with attribute "alloc_align", "al- loc_size", "assume_aligned", "format", "format_arg", "malloc", or "nonnull" is declared without it. Attributes "deprecated", "er- ror", and "warning" suppress the warning.. You can use the "copy" attribute to apply the same set of at- tributes to a declaration as that on another declaration without explicitly enumerating the attributes. This attribute can be ap- plied to declarations of functions, variables, or types. --WWmmiissssiinngg--aattttrriibbuutteess is enabled by --WWaallll. For example, since the declaration of the primary function template below makes use of both attribute "malloc" and "alloc_size" the declaration of the explicit specialization of the template is diag- nosed because it is missing one of the attributes. template T* __attribute__ ((malloc, alloc_size (1))) allocate (size_t); template <> void* __attribute__ ((malloc)) // missing alloc_size allocate (size_t); --WWmmiissssiinngg--bbrraacceess Warn if an aggregate or union initializer is not fully bracketed. In the following example, the initializer for "a" is not fully bracketed, but that for "b" is fully bracketed. int a[2][2] = { 0, 1, 2, 3 }; int b[2][2] = { { 0, 1 }, { 2, 3 } }; This warning is enabled by --WWaallll. --WWmmiissssiinngg--iinncclluuddee--ddiirrss (C, C++, Objective-C, Objective-C++ and Fortran only) Warn if a user-supplied include directory does not exist. This opi- ons is disabled by default for C, C++, Objective-C and Objective-C++. For Fortran, it is partially enabled by default by warning for -I and -J, only. --WWnnoo--mmiissssiinngg--pprrooffiillee This option controls warnings if feedback profiles are missing when using the --ffpprrooffiillee--uussee option. This option diagnoses those cases where a new function or a new file is added between compiling with --ffpprrooffiillee--ggeenneerraattee and with --ffpprrooffiillee--uussee, without regenerating the profiles. In these cases, the profile feedback data files do not contain any profile feedback information for the newly added func- tion or file respectively. Also, in the case when profile count data (.gcda) files are removed, GCC cannot use any profile feedback information. In all these cases, warnings are issued to inform you that a profile generation step is due. Ignoring the warning can result in poorly optimized code. --WWnnoo--mmiissssiinngg--pprrooffiillee can be used to disable the warning, but this is not recommended and should be done only when non-existent profile data is justified. --WWmmiissmmaattcchheedd--ddeeaalllloocc Warn for calls to deallocation functions with pointer arguments re- turned from from allocations functions for which the former isn't a suitable deallocator. A pair of functions can be associated as matching allocators and deallocators by use of attribute "malloc". Unless disabled by the --ffnnoo--bbuuiillttiinn option the standard functions "calloc", "malloc", "realloc", and "free", as well as the corre- sponding forms of C++ "operator new" and "operator delete" are im- plicitly associated as matching allocators and deallocators. In the following example "mydealloc" is the deallocator for pointers returned from "myalloc". void mydealloc (void*); __attribute__ ((malloc (mydealloc, 1))) void* myalloc (size_t); void f (void) { void *p = myalloc (32); // ...use p... free (p); // warning: not a matching deallocator for myalloc mydealloc (p); // ok } In C++, the related option --WWmmiissmmaattcchheedd--nneeww--ddeelleettee diagnoses mis- matches involving either "operator new" or "operator delete". Option --WWmmiissmmaattcchheedd--ddeeaalllloocc is included in --WWaallll. --WWmmuullttiissttaatteemmeenntt--mmaaccrrooss Warn about unsafe multiple statement macros that appear to be guarded by a clause such as "if", "else", "for", "switch", or "while", in which only the first statement is actually guarded af- ter the macro is expanded. For example: #define DOIT x++; y++ if (c) DOIT; will increment "y" unconditionally, not just when "c" holds. The can usually be fixed by wrapping the macro in a do-while loop: #define DOIT do { x++; y++; } while (0) if (c) DOIT; This warning is enabled by --WWaallll in C and C++. --WWppaarreenntthheesseess Warn if parentheses are omitted in certain contexts, such as when there is an assignment in a context where a truth value is ex- pected, or when operators are nested whose precedence people often get confused about. Also warn if a comparison like "x<=y<=z" appears; this is equiva- lent to "(x<=y ? 1 : 0) <= z", which is a different interpretation from that of ordinary mathematical notation. Also warn for dangerous uses of the GNU extension to "?:" with omitted middle operand. When the condition in the "?": operator is a boolean expression, the omitted value is always 1. Often pro- grammers expect it to be a value computed inside the conditional expression instead. For C++ this also warns for some cases of unnecessary parentheses in declarations, which can indicate an attempt at a function call instead of a declaration: { // Declares a local variable called mymutex. std::unique_lock (mymutex); // User meant std::unique_lock lock (mymutex); } This warning is enabled by --WWaallll. --WWsseeqquueennccee--ppooiinntt Warn about code that may have undefined semantics because of viola- tions of sequence point rules in the C and C++ standards. The C and C++ standards define the order in which expressions in a C/C++ program are evaluated in terms of _s_e_q_u_e_n_c_e _p_o_i_n_t_s, which rep- resent a partial ordering between the execution of parts of the program: those executed before the sequence point, and those exe- cuted after it. These occur after the evaluation of a full expres- sion (one which is not part of a larger expression), after the evaluation of the first operand of a "&&", "||", "? :" or "," (comma) operator, before a function is called (but after the evalu- ation of its arguments and the expression denoting the called func- tion), and in certain other places. Other than as expressed by the sequence point rules, the order of evaluation of subexpressions of an expression is not specified. All these rules describe only a partial order rather than a total order, since, for example, if two functions are called within one expression with no sequence point between them, the order in which the functions are called is not specified. However, the standards committee have ruled that func- tion calls do not overlap. It is not specified when between sequence points modifications to the values of objects take effect. Programs whose behavior depends on this have undefined behavior; the C and C++ standards specify that "Between the previous and next sequence point an object shall have its stored value modified at most once by the evaluation of an expression. Furthermore, the prior value shall be read only to de- termine the value to be stored.". If a program breaks these rules, the results on any particular implementation are entirely unpre- dictable. Examples of code with undefined behavior are "a = a++;", "a[n] = b[n++]" and "a[i++] = i;". Some more complicated cases are not di- agnosed by this option, and it may give an occasional false posi- tive result, but in general it has been found fairly effective at detecting this sort of problem in programs. The C++17 standard will define the order of evaluation of operands in more cases: in particular it requires that the right-hand side of an assignment be evaluated before the left-hand side, so the above examples are no longer undefined. But this option will still warn about them, to help people avoid writing code that is unde- fined in C and earlier revisions of C++. The standard is worded confusingly, therefore there is some debate over the precise meaning of the sequence point rules in subtle cases. Links to discussions of the problem, including proposed formal definitions, may be found on the GCC readings page, at . This warning is enabled by --WWaallll for C and C++. --WWnnoo--rreettuurrnn--llooccaall--aaddddrr Do not warn about returning a pointer (or in C++, a reference) to a variable that goes out of scope after the function returns. --WWrreettuurrnn--ttyyppee Warn whenever a function is defined with a return type that de- faults to "int". Also warn about any "return" statement with no return value in a function whose return type is not "void" (falling off the end of the function body is considered returning without a value). For C only, warn about a "return" statement with an expression in a function whose return type is "void", unless the expression type is also "void". As a GNU extension, the latter case is accepted with- out a warning unless --WWppeeddaannttiicc is used. Attempting to use the re- turn value of a non-"void" function other than "main" that flows off the end by reaching the closing curly brace that terminates the function is undefined. Unlike in C, in C++, flowing off the end of a non-"void" function other than "main" results in undefined behavior even when the value of the function is not used. This warning is enabled by default in C++ and by --WWaallll otherwise. --WWnnoo--sshhiifftt--ccoouunntt--nneeggaattiivvee Controls warnings if a shift count is negative. This warning is enabled by default. --WWnnoo--sshhiifftt--ccoouunntt--oovveerrffllooww Controls warnings if a shift count is greater than or equal to the bit width of the type. This warning is enabled by default. --WWsshhiifftt--nneeggaattiivvee--vvaalluuee Warn if left shifting a negative value. This warning is enabled by --WWeexxttrraa in C99 (and newer) and C++11 to C++17 modes. --WWnnoo--sshhiifftt--oovveerrffllooww --WWsshhiifftt--oovveerrffllooww==_n These options control warnings about left shift overflows. --WWsshhiifftt--oovveerrffllooww==11 This is the warning level of --WWsshhiifftt--oovveerrffllooww and is enabled by default in C99 and C++11 modes (and newer). This warning level does not warn about left-shifting 1 into the sign bit. (How- ever, in C, such an overflow is still rejected in contexts where an integer constant expression is required.) No warning is emitted in C++20 mode (and newer), as signed left shifts al- ways wrap. --WWsshhiifftt--oovveerrffllooww==22 This warning level also warns about left-shifting 1 into the sign bit, unless C++14 mode (or newer) is active. --WWsswwiittcchh Warn whenever a "switch" statement has an index of enumerated type and lacks a "case" for one or more of the named codes of that enu- meration. (The presence of a "default" label prevents this warn- ing.) "case" labels outside the enumeration range also provoke warnings when this option is used (even if there is a "default" la- bel). This warning is enabled by --WWaallll. --WWsswwiittcchh--ddeeffaauulltt Warn whenever a "switch" statement does not have a "default" case. --WWsswwiittcchh--eennuumm Warn whenever a "switch" statement has an index of enumerated type and lacks a "case" for one or more of the named codes of that enu- meration. "case" labels outside the enumeration range also provoke warnings when this option is used. The only difference between --WWsswwiittcchh and this option is that this option gives a warning about an omitted enumeration code even if there is a "default" label. --WWnnoo--sswwiittcchh--bbooooll Do not warn when a "switch" statement has an index of boolean type and the case values are outside the range of a boolean type. It is possible to suppress this warning by casting the controlling ex- pression to a type other than "bool". For example: switch ((int) (a == 4)) { ... } This warning is enabled by default for C and C++ programs. --WWnnoo--sswwiittcchh--oouuttssiiddee--rraannggee This option controls warnings when a "switch" case has a value that is outside of its respective type range. This warning is enabled by default for C and C++ programs. --WWnnoo--sswwiittcchh--uunnrreeaacchhaabbllee Do not warn when a "switch" statement contains statements between the controlling expression and the first case label, which will never be executed. For example: switch (cond) { i = 15; ... case 5: ... } --WWsswwiittcchh--uunnrreeaacchhaabbllee does not warn if the statement between the controlling expression and the first case label is just a declara- tion: switch (cond) { int i; ... case 5: i = 5; ... } This warning is enabled by default for C and C++ programs. --WWssyynncc--nnaanndd (C and C++ only) Warn when "__sync_fetch_and_nand" and "__sync_nand_and_fetch" built-in functions are used. These functions changed semantics in GCC 4.4. --WWttrriivviiaall--aauuttoo--vvaarr--iinniitt Warn when "-ftrivial-auto-var-init" cannot initialize the automatic variable. A common situation is an automatic variable that is de- clared between the controlling expression and the first case label of a "switch" statement. --WWuunnuusseedd--bbuutt--sseett--ppaarraammeetteerr Warn whenever a function parameter is assigned to, but otherwise unused (aside from its declaration). To suppress this warning use the "unused" attribute. This warning is also enabled by --WWuunnuusseedd together with --WWeexxttrraa. --WWuunnuusseedd--bbuutt--sseett--vvaarriiaabbllee Warn whenever a local variable is assigned to, but otherwise unused (aside from its declaration). This warning is enabled by --WWaallll. To suppress this warning use the "unused" attribute. This warning is also enabled by --WWuunnuusseedd, which is enabled by --WWaallll. --WWuunnuusseedd--ffuunnccttiioonn Warn whenever a static function is declared but not defined or a non-inline static function is unused. This warning is enabled by --WWaallll. --WWuunnuusseedd--llaabbeell Warn whenever a label is declared but not used. This warning is enabled by --WWaallll. To suppress this warning use the "unused" attribute. --WWuunnuusseedd--llooccaall--ttyyppeeddeeffss (C, Objective-C, C++ and Objective-C++ only) Warn when a typedef locally defined in a function is not used. This warning is enabled by --WWaallll. --WWuunnuusseedd--ppaarraammeetteerr Warn whenever a function parameter is unused aside from its decla- ration. To suppress this warning use the "unused" attribute. --WWnnoo--uunnuusseedd--rreessuulltt Do not warn if a caller of a function marked with attribute "warn_unused_result" does not use its return value. The default is --WWuunnuusseedd--rreessuulltt. --WWuunnuusseedd--vvaarriiaabbllee Warn whenever a local or static variable is unused aside from its declaration. This option implies --WWuunnuusseedd--ccoonnsstt--vvaarriiaabbllee==11 for C, but not for C++. This warning is enabled by --WWaallll. To suppress this warning use the "unused" attribute. --WWuunnuusseedd--ccoonnsstt--vvaarriiaabbllee --WWuunnuusseedd--ccoonnsstt--vvaarriiaabbllee==_n Warn whenever a constant static variable is unused aside from its declaration. --WWuunnuusseedd--ccoonnsstt--vvaarriiaabbllee==11 is enabled by --WWuunnuusseedd--vvaarriiaabbllee for C, but not for C++. In C this declares vari- able storage, but in C++ this is not an error since const variables take the place of "#define"s. To suppress this warning use the "unused" attribute. --WWuunnuusseedd--ccoonnsstt--vvaarriiaabbllee==11 This is the warning level that is enabled by --WWuunnuusseedd--vvaarriiaabbllee for C. It warns only about unused static const variables de- fined in the main compilation unit, but not about static const variables declared in any header included. --WWuunnuusseedd--ccoonnsstt--vvaarriiaabbllee==22 This warning level also warns for unused constant static vari- ables in headers (excluding system headers). This is the warn- ing level of --WWuunnuusseedd--ccoonnsstt--vvaarriiaabbllee and must be explicitly re- quested since in C++ this isn't an error and in C it might be harder to clean up all headers included. --WWuunnuusseedd--vvaalluuee Warn whenever a statement computes a result that is explicitly not used. To suppress this warning cast the unused expression to "void". This includes an expression-statement or the left-hand side of a comma expression that contains no side effects. For example, an expression such as "x[i,j]" causes a warning, while "x[(void)i,j]" does not. This warning is enabled by --WWaallll. --WWuunnuusseedd All the above --WWuunnuusseedd options combined. In order to get a warning about an unused function parameter, you must either specify --WWeexxttrraa --WWuunnuusseedd (note that --WWaallll implies --WWuunnuusseedd), or separately specify --WWuunnuusseedd--ppaarraammeetteerr. --WWuunniinniittiiaalliizzeedd Warn if an object with automatic or allocated storage duration is used without having been initialized. In C++, also warn if a non- static reference or non-static "const" member appears in a class without constructors. In addition, passing a pointer (or in C++, a reference) to an uninitialized object to a "const"-qualified argument of a built-in function known to read the object is also diagnosed by this warn- ing. (--WWmmaayybbee--uunniinniittiiaalliizzeedd is issued for ordinary functions.) If you want to warn about code that uses the uninitialized value of the variable in its own initializer, use the --WWiinniitt--sseellff option. These warnings occur for individual uninitialized elements of structure, union or array variables as well as for variables that are uninitialized as a whole. They do not occur for variables or elements declared "volatile". Because these warnings depend on op- timization, the exact variables or elements for which there are warnings depend on the precise optimization options and version of GCC used. Note that there may be no warning about a variable that is used only to compute a value that itself is never used, because such computations may be deleted by data flow analysis before the warn- ings are printed. In C++, this warning also warns about using uninitialized objects in member-initializer-lists. For example, GCC warns about "b" be- ing uninitialized in the following snippet: struct A { int a; int b; A() : a(b) { } }; --WWnnoo--iinnvvaalliidd--mmeemmoorryy--mmooddeell This option controls warnings for invocations of ____aattoommiicc BBuuiillttiinnss, ____ssyynncc BBuuiillttiinnss, and the C11 atomic generic functions with a memory consistency argument that is either invalid for the operation or outside the range of values of the "memory_order" enumeration. For example, since the "__atomic_store" and "__atomic_store_n" built- ins are only defined for the relaxed, release, and sequentially consistent memory orders the following code is diagnosed: void store (int *i) { __atomic_store_n (i, 0, memory_order_consume); } --WWiinnvvaalliidd--mmeemmoorryy--mmooddeell is enabled by default. --WWmmaayybbee--uunniinniittiiaalliizzeedd For an object with automatic or allocated storage duration, if there exists a path from the function entry to a use of the object that is initialized, but there exist some other paths for which the object is not initialized, the compiler emits a warning if it can- not prove the uninitialized paths are not executed at run time. In addition, passing a pointer (or in C++, a reference) to an uninitialized object to a "const"-qualified function argument is also diagnosed by this warning. (--WWuunniinniittiiaalliizzeedd is issued for built-in functions known to read the object.) Annotating the func- tion with attribute "access (none)" indicates that the argument isn't used to access the object and avoids the warning. These warnings are only possible in optimizing compilation, because otherwise GCC does not keep track of the state of variables. These warnings are made optional because GCC may not be able to de- termine when the code is correct in spite of appearing to have an error. Here is one example of how this can happen: { int x; switch (y) { case 1: x = 1; break; case 2: x = 4; break; case 3: x = 5; } foo (x); } If the value of "y" is always 1, 2 or 3, then "x" is always ini- tialized, but GCC doesn't know this. To suppress the warning, you need to provide a default case with _a_s_s_e_r_t(0) or similar code. This option also warns when a non-volatile automatic variable might be changed by a call to "longjmp". The compiler sees only the calls to "setjmp". It cannot know where "longjmp" will be called; in fact, a signal handler could call it at any point in the code. As a result, you may get a warning even when there is in fact no problem because "longjmp" cannot in fact be called at the place that would cause a problem. Some spurious warnings can be avoided if you declare all the func- tions you use that never return as "noreturn". This warning is enabled by --WWaallll or --WWeexxttrraa. --WWuunnkknnoowwnn--pprraaggmmaass Warn when a "#pragma" directive is encountered that is not under- stood by GCC. If this command-line option is used, warnings are even issued for unknown pragmas in system header files. This is not the case if the warnings are only enabled by the --WWaallll command- line option. --WWnnoo--pprraaggmmaass Do not warn about misuses of pragmas, such as incorrect parameters, invalid syntax, or conflicts between pragmas. See also --WWuunn-- kknnoowwnn--pprraaggmmaass. --WWnnoo--pprriioo--ccttoorr--ddttoorr Do not warn if a priority from 0 to 100 is used for constructor or destructor. The use of constructor and destructor attributes allow you to assign a priority to the constructor/destructor to control its order of execution before "main" is called or after it returns. The priority values must be greater than 100 as the compiler re- serves priority values between 0--100 for the implementation. --WWssttrriicctt--aalliiaassiinngg This option is only active when --ffssttrriicctt--aalliiaassiinngg is active. It warns about code that might break the strict aliasing rules that the compiler is using for optimization. The warning does not catch all cases, but does attempt to catch the more common pitfalls. It is included in --WWaallll. It is equivalent to --WWssttrriicctt--aalliiaassiinngg==33 --WWssttrriicctt--aalliiaassiinngg==nn This option is only active when --ffssttrriicctt--aalliiaassiinngg is active. It warns about code that might break the strict aliasing rules that the compiler is using for optimization. Higher levels correspond to higher accuracy (fewer false positives). Higher levels also correspond to more effort, similar to the way --OO works. --WWssttrriicctt--aalliiaassiinngg is equivalent to --WWssttrriicctt--aalliiaassiinngg==33. Level 1: Most aggressive, quick, least accurate. Possibly useful when higher levels do not warn but --ffssttrriicctt--aalliiaassiinngg still breaks the code, as it has very few false negatives. However, it has many false positives. Warns for all pointer conversions between possi- bly incompatible types, even if never dereferenced. Runs in the front end only. Level 2: Aggressive, quick, not too precise. May still have many false positives (not as many as level 1 though), and few false neg- atives (but possibly more than level 1). Unlike level 1, it only warns when an address is taken. Warns about incomplete types. Runs in the front end only. Level 3 (default for --WWssttrriicctt--aalliiaassiinngg): Should have very few false positives and few false negatives. Slightly slower than levels 1 or 2 when optimization is enabled. Takes care of the common pun+dereference pattern in the front end: "*(int*)&some_float". If optimization is enabled, it also runs in the back end, where it deals with multiple statement cases using flow-sensitive points-to information. Only warns when the converted pointer is derefer- enced. Does not warn about incomplete types. --WWssttrriicctt--oovveerrffllooww --WWssttrriicctt--oovveerrffllooww==_n This option is only active when signed overflow is undefined. It warns about cases where the compiler optimizes based on the assump- tion that signed overflow does not occur. Note that it does not warn about all cases where the code might overflow: it only warns about cases where the compiler implements some optimization. Thus this warning depends on the optimization level. An optimization that assumes that signed overflow does not occur is perfectly safe if the values of the variables involved are such that overflow never does, in fact, occur. Therefore this warning can easily give a false positive: a warning about code that is not actually a problem. To help focus on important issues, several warning levels are defined. No warnings are issued for the use of undefined signed overflow when estimating how many iterations a loop requires, in particular when determining whether a loop will be executed at all. --WWssttrriicctt--oovveerrffllooww==11 Warn about cases that are both questionable and easy to avoid. For example the compiler simplifies "x + 1 > x" to 1. This level of --WWssttrriicctt--oovveerrffllooww is enabled by --WWaallll; higher levels are not, and must be explicitly requested. --WWssttrriicctt--oovveerrffllooww==22 Also warn about other cases where a comparison is simplified to a constant. For example: "abs (x) >= 0". This can only be simplified when signed integer overflow is undefined, because "abs (INT_MIN)" overflows to "INT_MIN", which is less than zero. --WWssttrriicctt--oovveerrffllooww (with no level) is the same as --WWssttrriicctt--oovveerrffllooww==22. --WWssttrriicctt--oovveerrffllooww==33 Also warn about other cases where a comparison is simplified. For example: "x + 1 > 1" is simplified to "x > 0". --WWssttrriicctt--oovveerrffllooww==44 Also warn about other simplifications not covered by the above cases. For example: "(x * 10) / 5" is simplified to "x * 2". --WWssttrriicctt--oovveerrffllooww==55 Also warn about cases where the compiler reduces the magnitude of a constant involved in a comparison. For example: "x + 2 > y" is simplified to "x + 1 >= y". This is reported only at the highest warning level because this simplification applies to many comparisons, so this warning level gives a very large num- ber of false positives. --WWssttrriinngg--ccoommppaarree Warn for calls to "strcmp" and "strncmp" whose result is determined to be either zero or non-zero in tests for such equality owing to the length of one argument being greater than the size of the array the other argument is stored in (or the bound in the case of "strncmp"). Such calls could be mistakes. For example, the call to "strcmp" below is diagnosed because its result is necessarily non-zero irrespective of the contents of the array "a". extern char a[4]; void f (char *d) { strcpy (d, "string"); ... if (0 == strcmp (a, d)) // cannot be true puts ("a and d are the same"); } --WWssttrriinngg--ccoommppaarree is enabled by --WWeexxttrraa. --WWnnoo--ssttrriinnggoopp--oovveerrffllooww --WWssttrriinnggoopp--oovveerrffllooww --WWssttrriinnggoopp--oovveerrffllooww==_t_y_p_e Warn for calls to string manipulation functions such as "memcpy" and "strcpy" that are determined to overflow the destination buf- fer. The optional argument is one greater than the type of Object Size Checking to perform to determine the size of the destination. The argument is meaningful only for functions that operate on char- acter arrays but not for raw memory functions like "memcpy" which always make use of Object Size type-0. The option also warns for calls that specify a size in excess of the largest possible object or at most "SIZE_MAX / 2" bytes. The option produces the best re- sults with optimization enabled but can detect a small subset of simple buffer overflows even without optimization in calls to the GCC built-in functions like "__builtin_memcpy" that correspond to the standard functions. In any case, the option warns about just a subset of buffer overflows detected by the corresponding overflow checking built-ins. For example, the option issues a warning for the "strcpy" call below because it copies at least 5 characters (the string "blue" including the terminating NUL) into the buffer of size 4. enum Color { blue, purple, yellow }; const char* f (enum Color clr) { static char buf [4]; const char *str; switch (clr) { case blue: str = "blue"; break; case purple: str = "purple"; break; case yellow: str = "yellow"; break; } return strcpy (buf, str); // warning here } Option --WWssttrriinnggoopp--oovveerrffllooww==22 is enabled by default. --WWssttrriinnggoopp--oovveerrffllooww --WWssttrriinnggoopp--oovveerrffllooww==11 The --WWssttrriinnggoopp--oovveerrffllooww==11 option uses type-zero Object Size Checking to determine the sizes of destination objects. At this setting the option does not warn for writes past the end of subobjects of larger objects accessed by pointers unless the size of the largest surrounding object is known. When the des- tination may be one of several objects it is assumed to be the largest one of them. On Linux systems, when optimization is enabled at this setting the option warns for the same code as when the "_FORTIFY_SOURCE" macro is defined to a non-zero value. --WWssttrriinnggoopp--oovveerrffllooww==22 The --WWssttrriinnggoopp--oovveerrffllooww==22 option uses type-one Object Size Checking to determine the sizes of destination objects. At this setting the option warns about overflows when writing to members of the largest complete objects whose exact size is known. However, it does not warn for excessive writes to the same members of unknown objects referenced by pointers since they may point to arrays containing unknown numbers of ele- ments. This is the default setting of the option. --WWssttrriinnggoopp--oovveerrffllooww==33 The --WWssttrriinnggoopp--oovveerrffllooww==33 option uses type-two Object Size Checking to determine the sizes of destination objects. At this setting the option warns about overflowing the smallest object or data member. This is the most restrictive setting of the option that may result in warnings for safe code. --WWssttrriinnggoopp--oovveerrffllooww==44 The --WWssttrriinnggoopp--oovveerrffllooww==44 option uses type-three Object Size Checking to determine the sizes of destination objects. At this setting the option warns about overflowing any data mem- bers, and when the destination is one of several objects it uses the size of the largest of them to decide whether to issue a warning. Similarly to --WWssttrriinnggoopp--oovveerrffllooww==33 this setting of the option may result in warnings for benign code. --WWnnoo--ssttrriinnggoopp--oovveerrrreeaadd Warn for calls to string manipulation functions such as "memchr", or "strcpy" that are determined to read past the end of the source sequence. Option --WWssttrriinnggoopp--oovveerrrreeaadd is enabled by default. --WWnnoo--ssttrriinnggoopp--ttrruunnccaattiioonn Do not warn for calls to bounded string manipulation functions such as "strncat", "strncpy", and "stpncpy" that may either truncate the copied string or leave the destination unchanged. In the following example, the call to "strncat" specifies a bound that is less than the length of the source string. As a result, the copy of the source will be truncated and so the call is diag- nosed. To avoid the warning use "bufsize - strlen (buf) - 1)" as the bound. void append (char *buf, size_t bufsize) { strncat (buf, ".txt", 3); } As another example, the following call to "strncpy" results in copying to "d" just the characters preceding the terminating NUL, without appending the NUL to the end. Assuming the result of "strncpy" is necessarily a NUL-terminated string is a common mis- take, and so the call is diagnosed. To avoid the warning when the result is not expected to be NUL-terminated, call "memcpy" instead. void copy (char *d, const char *s) { strncpy (d, s, strlen (s)); } In the following example, the call to "strncpy" specifies the size of the destination buffer as the bound. If the length of the source string is equal to or greater than this size the result of the copy will not be NUL-terminated. Therefore, the call is also diagnosed. To avoid the warning, specify "sizeof buf - 1" as the bound and set the last element of the buffer to "NUL". void copy (const char *s) { char buf[80]; strncpy (buf, s, sizeof buf); ... } In situations where a character array is intended to store a se- quence of bytes with no terminating "NUL" such an array may be an- notated with attribute "nonstring" to avoid this warning. Such ar- rays, however, are not suitable arguments to functions that expect "NUL"-terminated strings. To help detect accidental misuses of such arrays GCC issues warnings unless it can prove that the use is safe. --WWssuuggggeesstt--aattttrriibbuuttee==[ppuurree|ccoonnsstt|nnoorreettuurrnn|ffoorrmmaatt|ccoolldd|mmaalllloocc] Warn for cases where adding an attribute may be beneficial. The at- tributes currently supported are listed below. --WWssuuggggeesstt--aattttrriibbuuttee==ppuurree --WWssuuggggeesstt--aattttrriibbuuttee==ccoonnsstt --WWssuuggggeesstt--aattttrriibbuuttee==nnoorreettuurrnn --WWmmiissssiinngg--nnoorreettuurrnn --WWssuuggggeesstt--aattttrriibbuuttee==mmaalllloocc Warn about functions that might be candidates for attributes "pure", "const" or "noreturn" or "malloc". The compiler only warns for functions visible in other compilation units or (in the case of "pure" and "const") if it cannot prove that the function returns normally. A function returns normally if it doesn't contain an infinite loop or return abnormally by throw- ing, calling "abort" or trapping. This analysis requires op- tion --ffiippaa--ppuurree--ccoonnsstt, which is enabled by default at --OO and higher. Higher optimization levels improve the accuracy of the analysis. --WWssuuggggeesstt--aattttrriibbuuttee==ffoorrmmaatt --WWmmiissssiinngg--ffoorrmmaatt--aattttrriibbuuttee Warn about function pointers that might be candidates for "for- mat" attributes. Note these are only possible candidates, not absolute ones. GCC guesses that function pointers with "for- mat" attributes that are used in assignment, initialization, parameter passing or return statements should have a corre- sponding "format" attribute in the resulting type. I.e. the left-hand side of the assignment or initialization, the type of the parameter variable, or the return type of the containing function respectively should also have a "format" attribute to avoid the warning. GCC also warns about function definitions that might be candi- dates for "format" attributes. Again, these are only possible candidates. GCC guesses that "format" attributes might be ap- propriate for any function that calls a function like "vprintf" or "vscanf", but this might not always be the case, and some functions for which "format" attributes are appropriate may not be detected. --WWssuuggggeesstt--aattttrriibbuuttee==ccoolldd Warn about functions that might be candidates for "cold" attri- bute. This is based on static detection and generally only warns about functions which always leads to a call to another "cold" function such as wrappers of C++ "throw" or fatal error reporting functions leading to "abort". --WWaalllloocc--zzeerroo Warn about calls to allocation functions decorated with attribute "alloc_size" that specify zero bytes, including those to the built- in forms of the functions "aligned_alloc", "alloca", "calloc", "malloc", and "realloc". Because the behavior of these functions when called with a zero size differs among implementations (and in the case of "realloc" has been deprecated) relying on it may result in subtle portability bugs and should be avoided. --WWaalllloocc--ssiizzee--llaarrggeerr--tthhaann==_b_y_t_e_-_s_i_z_e Warn about calls to functions decorated with attribute "alloc_size" that attempt to allocate objects larger than the specified number of bytes, or where the result of the size computation in an integer type with infinite precision would exceed the value of PPTTRRDDIIFFFF__MMAAXX on the target. --WWaalllloocc--ssiizzee--llaarrggeerr--tthhaann==PPTTRRDDIIFFFF__MMAAXX is enabled by default. Warnings controlled by the option can be disabled either by specifying _b_y_t_e_-_s_i_z_e of SSIIZZEE__MMAAXX or more or by --WWnnoo--aall-- lloocc--ssiizzee--llaarrggeerr--tthhaann. --WWnnoo--aalllloocc--ssiizzee--llaarrggeerr--tthhaann Disable --WWaalllloocc--ssiizzee--llaarrggeerr--tthhaann== warnings. The option is equiva- lent to --WWaalllloocc--ssiizzee--llaarrggeerr--tthhaann==SSIIZZEE__MMAAXX or larger. --WWaallllooccaa This option warns on all uses of "alloca" in the source. --WWaallllooccaa--llaarrggeerr--tthhaann==_b_y_t_e_-_s_i_z_e This option warns on calls to "alloca" with an integer argument whose value is either zero, or that is not bounded by a controlling predicate that limits its value to at most _b_y_t_e_-_s_i_z_e. It also warns for calls to "alloca" where the bound value is unknown. Ar- guments of non-integer types are considered unbounded even if they appear to be constrained to the expected range. For example, a bounded case of "alloca" could be: void func (size_t n) { void *p; if (n <= 1000) p = alloca (n); else p = malloc (n); f (p); } In the above example, passing "-Walloca-larger-than=1000" would not issue a warning because the call to "alloca" is known to be at most 1000 bytes. However, if "-Walloca-larger-than=500" were passed, the compiler would emit a warning. Unbounded uses, on the other hand, are uses of "alloca" with no controlling predicate constraining its integer argument. For exam- ple: void func () { void *p = alloca (n); f (p); } If "-Walloca-larger-than=500" were passed, the above would trigger a warning, but this time because of the lack of bounds checking. Note, that even seemingly correct code involving signed integers could cause a warning: void func (signed int n) { if (n < 500) { p = alloca (n); f (p); } } In the above example, _n could be negative, causing a larger than expected argument to be implicitly cast into the "alloca" call. This option also warns when "alloca" is used in a loop. --WWaallllooccaa--llaarrggeerr--tthhaann==PPTTRRDDIIFFFF__MMAAXX is enabled by default but is usu- ally only effective when --ffttrreeee--vvrrpp is active (default for --OO22 and above). See also --WWvvllaa--llaarrggeerr--tthhaann==bbyyttee--ssiizzee. --WWnnoo--aallllooccaa--llaarrggeerr--tthhaann Disable --WWaallllooccaa--llaarrggeerr--tthhaann== warnings. The option is equivalent to --WWaallllooccaa--llaarrggeerr--tthhaann==SSIIZZEE__MMAAXX or larger. --WWaarriitthh--ccoonnvveerrssiioonn Do warn about implicit conversions from arithmetic operations even when conversion of the operands to the same type cannot change their values. This affects warnings from --WWccoonnvveerrssiioonn, --WWffllooaatt--ccoonnvveerrssiioonn, and --WWssiiggnn--ccoonnvveerrssiioonn. void f (char c, int i) { c = c + i; // warns with B<-Wconversion> c = c + 1; // only warns with B<-Warith-conversion> } --WWaarrrraayy--bboouunnddss --WWaarrrraayy--bboouunnddss==_n Warn about out of bounds subscripts or offsets into arrays. This warning is enabled by --WWaallll. It is more effective when --ffttrreeee--vvrrpp is active (the default for --OO22 and above) but a subset of instances are issued even without optimization. --WWaarrrraayy--bboouunnddss==11 This is the default warning level of --WWaarrrraayy--bboouunnddss and is en- abled by --WWaallll; higher levels are not, and must be explicitly requested. --WWaarrrraayy--bboouunnddss==22 This warning level also warns about out of bounds accesses to trailing struct members of one-element array types and about the intermediate results of pointer arithmetic that may yield out of bounds values. This warning level may give a larger number of false positives and is deactivated by default. --WWaarrrraayy--ccoommppaarree Warn about equality and relational comparisons between two operands of array type. This comparison was deprecated in C++20. For exam- ple: int arr1[5]; int arr2[5]; bool same = arr1 == arr2; --WWaarrrraayy--ccoommppaarree is enabled by --WWaallll. --WWaarrrraayy--ppaarraammeetteerr --WWaarrrraayy--ppaarraammeetteerr==_n Warn about redeclarations of functions involving arguments of array or pointer types of inconsistent kinds or forms, and enable the de- tection of out-of-bounds accesses to such parameters by warnings such as --WWaarrrraayy--bboouunnddss. If the first function declaration uses the array form the bound specified in the array is assumed to be the minimum number of ele- ments expected to be provided in calls to the function and the max- imum number of elements accessed by it. Failing to provide argu- ments of sufficient size or accessing more than the maximum number of elements may be diagnosed by warnings such as --WWaarrrraayy--bboouunnddss. At level 1 the warning diagnoses inconsistencies involving array parameters declared using the "T[static N]" form. For example, the warning triggers for the following redeclarations because the first one allows an array of any size to be passed to "f" while the second one with the keyword "static" specifies that the array argument must have at least four elements. void f (int[static 4]); void f (int[]); // warning (inconsistent array form) void g (void) { int *p = (int *)malloc (4); f (p); // warning (array too small) ... } At level 2 the warning also triggers for redeclarations involving any other inconsistency in array or pointer argument forms denoting array sizes. Pointers and arrays of unspecified bound are consid- ered equivalent and do not trigger a warning. void g (int*); void g (int[]); // no warning void g (int[8]); // warning (inconsistent array bound) --WWaarrrraayy--ppaarraammeetteerr==22 is included in --WWaallll. The --WWvvllaa--ppaarraammeetteerr op- tion triggers warnings for similar inconsistencies involving Vari- able Length Array arguments. --WWaattttrriibbuuttee--aalliiaass==_n --WWnnoo--aattttrriibbuuttee--aalliiaass Warn about declarations using the "alias" and similar attributes whose target is incompatible with the type of the alias. --WWaattttrriibbuuttee--aalliiaass==11 The default warning level of the --WWaattttrriibbuuttee--aalliiaass option diag- noses incompatibilities between the type of the alias declara- tion and that of its target. Such incompatibilities are typi- cally indicative of bugs. --WWaattttrriibbuuttee--aalliiaass==22 At this level --WWaattttrriibbuuttee--aalliiaass also diagnoses cases where the attributes of the alias declaration are more restrictive than the attributes applied to its target. These mismatches can po- tentially result in incorrect code generation. In other cases they may be benign and could be resolved simply by adding the missing attribute to the target. For comparison, see the --WWmmiissssiinngg--aattttrriibbuutteess option, which controls diagnostics when the alias declaration is less restrictive than the target, rather than more restrictive. Attributes considered include "alloc_align", "alloc_size", "cold", "const", "hot", "leaf", "malloc", "nonnull", "nore- turn", "nothrow", "pure", "returns_nonnull", and "re- turns_twice". --WWaattttrriibbuuttee--aalliiaass is equivalent to --WWaattttrriibbuuttee--aalliiaass==11. This is the default. You can disable these warnings with either --WWnnoo--aatt-- ttrriibbuuttee--aalliiaass or --WWaattttrriibbuuttee--aalliiaass==00. --WWbbiiddii--cchhaarrss==[nnoonnee|uunnppaaiirreedd|aannyy|uuccnn] Warn about possibly misleading UTF-8 bidirectional control charac- ters in comments, string literals, character constants, and identi- fiers. Such characters can change left-to-right writing direction into right-to-left (and vice versa), which can cause confusion be- tween the logical order and visual order. This may be dangerous; for instance, it may seem that a piece of code is not commented out, whereas it in fact is. There are three levels of warning supported by GCC. The default is --WWbbiiddii--cchhaarrss==uunnppaaiirreedd, which warns about improperly terminated bidi contexts. --WWbbiiddii--cchhaarrss==nnoonnee turns the warning off. --WWbbiiddii--cchhaarrss==aannyy warns about any use of bidirectional control char- acters. By default, this warning does not warn about UCNs. It is, however, possible to turn on such checking by using --WWbbiiddii--cchhaarrss==uunn-- ppaaiirreedd,,uuccnn or --WWbbiiddii--cchhaarrss==aannyy,,uuccnn. Using --WWbbiiddii--cchhaarrss==uuccnn is valid, and is equivalent to --WWbbiiddii--cchhaarrss==uunnppaaiirreedd,,uuccnn, if no previ- ous --WWbbiiddii--cchhaarrss==aannyy was specified. --WWbbooooll--ccoommppaarree Warn about boolean expression compared with an integer value dif- ferent from "true"/"false". For instance, the following comparison is always false: int n = 5; ... if ((n > 1) == 2) { ... } This warning is enabled by --WWaallll. --WWbbooooll--ooppeerraattiioonn Warn about suspicious operations on expressions of a boolean type. For instance, bitwise negation of a boolean is very likely a bug in the program. For C, this warning also warns about incrementing or decrementing a boolean, which rarely makes sense. (In C++, decre- menting a boolean is always invalid. Incrementing a boolean is in- valid in C++17, and deprecated otherwise.) This warning is enabled by --WWaallll. --WWdduupplliiccaatteedd--bbrraanncchheess Warn when an if-else has identical branches. This warning detects cases like if (p != NULL) return 0; else return 0; It doesn't warn when both branches contain just a null statement. This warning also warn for conditional operators: int i = x ? *p : *p; --WWdduupplliiccaatteedd--ccoonndd Warn about duplicated conditions in an if-else-if chain. For in- stance, warn for the following code: if (p->q != NULL) { ... } else if (p->q != NULL) { ... } --WWffrraammee--aaddddrreessss Warn when the ____bbuuiillttiinn__ffrraammee__aaddddrreessss or ____bbuuiillttiinn__rreettuurrnn__aaddddrreessss is called with an argument greater than 0. Such calls may return indeterminate values or crash the program. The warning is included in --WWaallll. --WWnnoo--ddiissccaarrddeedd--qquuaalliiffiieerrss (C and Objective-C only) Do not warn if type qualifiers on pointers are being discarded. Typically, the compiler warns if a "const char *" variable is passed to a function that takes a "char *" parameter. This option can be used to suppress such a warning. --WWnnoo--ddiissccaarrddeedd--aarrrraayy--qquuaalliiffiieerrss (C and Objective-C only) Do not warn if type qualifiers on arrays which are pointer targets are being discarded. Typically, the compiler warns if a "const int (*)[]" variable is passed to a function that takes a "int (*)[]" parameter. This option can be used to suppress such a warning. --WWnnoo--iinnccoommppaattiibbllee--ppooiinntteerr--ttyyppeess (C and Objective-C only) Do not warn when there is a conversion between pointers that have incompatible types. This warning is for cases not covered by --WWnnoo--ppooiinntteerr--ssiiggnn, which warns for pointer argument passing or as- signment with different signedness. --WWnnoo--iinntt--ccoonnvveerrssiioonn (C and Objective-C only) Do not warn about incompatible integer to pointer and pointer to integer conversions. This warning is about implicit conversions; for explicit conversions the warnings --WWnnoo--iinntt--ttoo--ppooiinntteerr--ccaasstt and --WWnnoo--ppooiinntteerr--ttoo--iinntt--ccaasstt may be used. --WWzzeerroo--lleennggtthh--bboouunnddss Warn about accesses to elements of zero-length array members that might overlap other members of the same object. Declaring interior zero-length arrays is discouraged because accesses to them are un- defined. See For example, the first two stores in function "bad" are diagnosed because the array elements overlap the subsequent members "b" and "c". The third store is diagnosed by --WWaarrrraayy--bboouunnddss because it is beyond the bounds of the enclosing object. struct X { int a[0]; int b, c; }; struct X x; void bad (void) { x.a[0] = 0; // -Wzero-length-bounds x.a[1] = 1; // -Wzero-length-bounds x.a[2] = 2; // -Warray-bounds } Option --WWzzeerroo--lleennggtthh--bboouunnddss is enabled by --WWaarrrraayy--bboouunnddss. --WWnnoo--ddiivv--bbyy--zzeerroo Do not warn about compile-time integer division by zero. Floating- point division by zero is not warned about, as it can be a legiti- mate way of obtaining infinities and NaNs. --WWssyysstteemm--hheeaaddeerrss Print warning messages for constructs found in system header files. Warnings from system headers are normally suppressed, on the as- sumption that they usually do not indicate real problems and would only make the compiler output harder to read. Using this command- line option tells GCC to emit warnings from system headers as if they occurred in user code. However, note that using --WWaallll in con- junction with this option does _n_o_t warn about unknown pragmas in system headers---for that, --WWuunnkknnoowwnn--pprraaggmmaass must also be used. --WWttaauuttoollooggiiccaall--ccoommppaarree Warn if a self-comparison always evaluates to true or false. This warning detects various mistakes such as: int i = 1; ... if (i > i) { ... } This warning also warns about bitwise comparisons that always eval- uate to true or false, for instance: if ((a & 16) == 10) { ... } will always be false. This warning is enabled by --WWaallll. --WWttrraammppoolliinneess Warn about trampolines generated for pointers to nested functions. A trampoline is a small piece of data or code that is created at run time on the stack when the address of a nested function is taken, and is used to call the nested function indirectly. For some targets, it is made up of data only and thus requires no spe- cial treatment. But, for most targets, it is made up of code and thus requires the stack to be made executable in order for the pro- gram to work properly. --WWffllooaatt--eeqquuaall Warn if floating-point values are used in equality comparisons. The idea behind this is that sometimes it is convenient (for the programmer) to consider floating-point values as approximations to infinitely precise real numbers. If you are doing this, then you need to compute (by analyzing the code, or in some other way) the maximum or likely maximum error that the computation introduces, and allow for it when performing comparisons (and when producing output, but that's a different problem). In particular, instead of testing for equality, you should check to see whether the two val- ues have ranges that overlap; and this is done with the relational operators, so equality comparisons are probably mistaken. --WWttrraaddiittiioonnaall (C and Objective-C only) Warn about certain constructs that behave differently in tradi- tional and ISO C. Also warn about ISO C constructs that have no traditional C equivalent, and/or problematic constructs that should be avoided. * Macro parameters that appear within string literals in the macro body. In traditional C macro replacement takes place within string literals, but in ISO C it does not. * In traditional C, some preprocessor directives did not exist. Traditional preprocessors only considered a line to be a direc- tive if the ## appeared in column 1 on the line. Therefore --WWttrraaddiittiioonnaall warns about directives that traditional C under- stands but ignores because the ## does not appear as the first character on the line. It also suggests you hide directives like "#pragma" not understood by traditional C by indenting them. Some traditional implementations do not recognize "#elif", so this option suggests avoiding it altogether. * A function-like macro that appears without arguments. * The unary plus operator. * The UU integer constant suffix, or the FF or LL floating-point constant suffixes. (Traditional C does support the LL suffix on integer constants.) Note, these suffixes appear in macros de- fined in the system headers of most modern systems, e.g. the __MMIINN/__MMAAXX macros in "". Use of these macros in user code might normally lead to spurious warnings, however GCC's integrated preprocessor has enough context to avoid warning in these cases. * A function declared external in one block and then used after the end of the block. * A "switch" statement has an operand of type "long". * A non-"static" function declaration follows a "static" one. This construct is not accepted by some traditional C compilers. * The ISO type of an integer constant has a different width or signedness from its traditional type. This warning is only is- sued if the base of the constant is ten. I.e. hexadecimal or octal values, which typically represent bit patterns, are not warned about. * Usage of ISO string concatenation is detected. * Initialization of automatic aggregates. * Identifier conflicts with labels. Traditional C lacks a sepa- rate namespace for labels. * Initialization of unions. If the initializer is zero, the warning is omitted. This is done under the assumption that the zero initializer in user code appears conditioned on e.g. "__STDC__" to avoid missing initializer warnings and relies on default initialization to zero in the traditional C case. * Conversions by prototypes between fixed/floating-point values and vice versa. The absence of these prototypes when compiling with traditional C causes serious problems. This is a subset of the possible conversion warnings; for the full set use --WWttrraaddiittiioonnaall--ccoonnvveerrssiioonn. * Use of ISO C style function definitions. This warning inten- tionally is _n_o_t issued for prototype declarations or variadic functions because these ISO C features appear in your code when using libiberty's traditional C compatibility macros, "PARAMS" and "VPARAMS". This warning is also bypassed for nested func- tions because that feature is already a GCC extension and thus not relevant to traditional C compatibility. --WWttrraaddiittiioonnaall--ccoonnvveerrssiioonn (C and Objective-C only) Warn if a prototype causes a type conversion that is different from what would happen to the same argument in the absence of a proto- type. This includes conversions of fixed point to floating and vice versa, and conversions changing the width or signedness of a fixed-point argument except when the same as the default promotion. --WWddeeccllaarraattiioonn--aafftteerr--ssttaatteemmeenntt (C and Objective-C only) Warn when a declaration is found after a statement in a block. This construct, known from C++, was introduced with ISO C99 and is by default allowed in GCC. It is not supported by ISO C90. --WWsshhaaddooww Warn whenever a local variable or type declaration shadows another variable, parameter, type, class member (in C++), or instance vari- able (in Objective-C) or whenever a built-in function is shadowed. Note that in C++, the compiler warns if a local variable shadows an explicit typedef, but not if it shadows a struct/class/enum. If this warning is enabled, it includes also all instances of local shadowing. This means that --WWnnoo--sshhaaddooww==llooccaall and --WWnnoo--sshhaaddooww==ccoomm-- ppaattiibbllee--llooccaall are ignored when --WWsshhaaddooww is used. Same as --WWsshhaaddooww==gglloobbaall. --WWnnoo--sshhaaddooww--iivvaarr (Objective-C only) Do not warn whenever a local variable shadows an instance variable in an Objective-C method. --WWsshhaaddooww==gglloobbaall Warn for any shadowing. Same as --WWsshhaaddooww. --WWsshhaaddooww==llooccaall Warn when a local variable shadows another local variable or param- eter. --WWsshhaaddooww==ccoommppaattiibbllee--llooccaall Warn when a local variable shadows another local variable or param- eter whose type is compatible with that of the shadowing variable. In C++, type compatibility here means the type of the shadowing variable can be converted to that of the shadowed variable. The creation of this flag (in addition to --WWsshhaaddooww==llooccaall) is based on the idea that when a local variable shadows another one of incom- patible type, it is most likely intentional, not a bug or typo, as shown in the following example: for (SomeIterator i = SomeObj.begin(); i != SomeObj.end(); ++i) { for (int i = 0; i < N; ++i) { ... } ... } Since the two variable "i" in the example above have incompatible types, enabling only --WWsshhaaddooww==ccoommppaattiibbllee--llooccaall does not emit a warning. Because their types are incompatible, if a programmer ac- cidentally uses one in place of the other, type checking is ex- pected to catch that and emit an error or warning. Use of this flag instead of --WWsshhaaddooww==llooccaall can possibly reduce the number of warnings triggered by intentional shadowing. Note that this also means that shadowing "const char *i" by "char *i" does not emit a warning. This warning is also enabled by --WWsshhaaddooww==llooccaall. --WWllaarrggeerr--tthhaann==_b_y_t_e_-_s_i_z_e Warn whenever an object is defined whose size exceeds _b_y_t_e_-_s_i_z_e. --WWllaarrggeerr--tthhaann==PPTTRRDDIIFFFF__MMAAXX is enabled by default. Warnings con- trolled by the option can be disabled either by specifying _b_y_t_e_- _s_i_z_e of SSIIZZEE__MMAAXX or more or by --WWnnoo--llaarrggeerr--tthhaann. Also warn for calls to bounded functions such as "memchr" or "strnlen" that specify a bound greater than the largest possible object, which is PPTTRRDDIIFFFF__MMAAXX bytes by default. These warnings can only be disabled by --WWnnoo--llaarrggeerr--tthhaann. --WWnnoo--llaarrggeerr--tthhaann Disable --WWllaarrggeerr--tthhaann== warnings. The option is equivalent to --WWllaarrggeerr--tthhaann==SSIIZZEE__MMAAXX or larger. --WWffrraammee--llaarrggeerr--tthhaann==_b_y_t_e_-_s_i_z_e Warn if the size of a function frame exceeds _b_y_t_e_-_s_i_z_e. The compu- tation done to determine the stack frame size is approximate and not conservative. The actual requirements may be somewhat greater than _b_y_t_e_-_s_i_z_e even if you do not get a warning. In addition, any space allocated via "alloca", variable-length arrays, or related constructs is not included by the compiler when determining whether or not to issue a warning. --WWffrraammee--llaarrggeerr--tthhaann==PPTTRRDDIIFFFF__MMAAXX is en- abled by default. Warnings controlled by the option can be dis- abled either by specifying _b_y_t_e_-_s_i_z_e of SSIIZZEE__MMAAXX or more or by --WWnnoo--ffrraammee--llaarrggeerr--tthhaann. --WWnnoo--ffrraammee--llaarrggeerr--tthhaann Disable --WWffrraammee--llaarrggeerr--tthhaann== warnings. The option is equivalent to --WWffrraammee--llaarrggeerr--tthhaann==SSIIZZEE__MMAAXX or larger. --WWffrreeee--nnoonnhheeaapp--oobbjjeecctt Warn when attempting to deallocate an object that was either not allocated on the heap, or by using a pointer that was not returned from a prior call to the corresponding allocation function. For example, because the call to "stpcpy" returns a pointer to the ter- minating nul character and not to the beginning of the object, the call to "free" below is diagnosed. void f (char *p) { p = stpcpy (p, "abc"); // ... free (p); // warning } --WWffrreeee--nnoonnhheeaapp--oobbjjeecctt is included in --WWaallll. --WWssttaacckk--uussaaggee==_b_y_t_e_-_s_i_z_e Warn if the stack usage of a function might exceed _b_y_t_e_-_s_i_z_e. The computation done to determine the stack usage is conservative. Any space allocated via "alloca", variable-length arrays, or related constructs is included by the compiler when determining whether or not to issue a warning. The message is in keeping with the output of --ffssttaacckk--uussaaggee. * If the stack usage is fully static but exceeds the specified amount, it's: warning: stack usage is 1120 bytes * If the stack usage is (partly) dynamic but bounded, it's: warning: stack usage might be 1648 bytes * If the stack usage is (partly) dynamic and not bounded, it's: warning: stack usage might be unbounded --WWssttaacckk--uussaaggee==PPTTRRDDIIFFFF__MMAAXX is enabled by default. Warnings con- trolled by the option can be disabled either by specifying _b_y_t_e_- _s_i_z_e of SSIIZZEE__MMAAXX or more or by --WWnnoo--ssttaacckk--uussaaggee. --WWnnoo--ssttaacckk--uussaaggee Disable --WWssttaacckk--uussaaggee== warnings. The option is equivalent to --WWssttaacckk--uussaaggee==SSIIZZEE__MMAAXX or larger. --WWuunnssaaffee--lloooopp--ooppttiimmiizzaattiioonnss Warn if the loop cannot be optimized because the compiler cannot assume anything on the bounds of the loop indices. With --ffuunn-- ssaaffee--lloooopp--ooppttiimmiizzaattiioonnss warn if the compiler makes such assump- tions. --WWnnoo--ppeeddaannttiicc--mmss--ffoorrmmaatt (MinGW targets only) When used in combination with --WWffoorrmmaatt and --ppeeddaannttiicc without GNU extensions, this option disables the warnings about non-ISO "printf" / "scanf" format width specifiers "I32", "I64", and "I" used on Windows targets, which depend on the MS runtime. --WWppooiinntteerr--aarriitthh Warn about anything that depends on the "size of" a function type or of "void". GNU C assigns these types a size of 1, for conve- nience in calculations with "void *" pointers and pointers to func- tions. In C++, warn also when an arithmetic operation involves "NULL". This warning is also enabled by --WWppeeddaannttiicc. --WWnnoo--ppooiinntteerr--ccoommppaarree Do not warn if a pointer is compared with a zero character con- stant. This usually means that the pointer was meant to be deref- erenced. For example: const char *p = foo (); if (p == '\0') return 42; Note that the code above is invalid in C++11. This warning is enabled by default. --WWttssaann Warn about unsupported features in ThreadSanitizer. ThreadSanitizer does not support "std::atomic_thread_fence" and can report false positives. This warning is enabled by default. --WWttyyppee--lliimmiittss Warn if a comparison is always true or always false due to the lim- ited range of the data type, but do not warn for constant expres- sions. For example, warn if an unsigned variable is compared against zero with "<" or ">=". This warning is also enabled by --WWeexxttrraa. --WWaabbssoolluuttee--vvaalluuee (C and Objective-C only) Warn for calls to standard functions that compute the absolute value of an argument when a more appropriate standard function is available. For example, calling "abs(3.14)" triggers the warning because the appropriate function to call to compute the absolute value of a double argument is "fabs". The option also triggers warnings when the argument in a call to such a function has an un- signed type. This warning can be suppressed with an explicit type cast and it is also enabled by --WWeexxttrraa. --WWccoommmmeenntt --WWccoommmmeennttss Warn whenever a comment-start sequence //** appears in a //** comment, or whenever a backslash-newline appears in a //// comment. This warning is enabled by --WWaallll. --WWttrriiggrraapphhss Warn if any trigraphs are encountered that might change the meaning of the program. Trigraphs within comments are not warned about, except those that would form escaped newlines. This option is implied by --WWaallll. If --WWaallll is not given, this op- tion is still enabled unless trigraphs are enabled. To get tri- graph conversion without warnings, but get the other --WWaallll warn- ings, use --ttrriiggrraapphhss --WWaallll --WWnnoo--ttrriiggrraapphhss. --WWuunnddeeff Warn if an undefined identifier is evaluated in an "#if" directive. Such identifiers are replaced with zero. --WWeexxppaannssiioonn--ttoo--ddeeffiinneedd Warn whenever ddeeffiinneedd is encountered in the expansion of a macro (including the case where the macro is expanded by an ##iiff direc- tive). Such usage is not portable. This warning is also enabled by --WWppeeddaannttiicc and --WWeexxttrraa. --WWuunnuusseedd--mmaaccrrooss Warn about macros defined in the main file that are unused. A macro is _u_s_e_d if it is expanded or tested for existence at least once. The preprocessor also warns if the macro has not been used at the time it is redefined or undefined. Built-in macros, macros defined on the command line, and macros de- fined in include files are not warned about. _N_o_t_e_: If a macro is actually used, but only used in skipped condi- tional blocks, then the preprocessor reports it as unused. To avoid the warning in such a case, you might improve the scope of the macro's definition by, for example, moving it into the first skipped block. Alternatively, you could provide a dummy use with something like: #if defined the_macro_causing_the_warning #endif --WWnnoo--eennddiiff--llaabbeellss Do not warn whenever an "#else" or an "#endif" are followed by text. This sometimes happens in older programs with code of the form #if FOO ... #else FOO ... #endif FOO The second and third "FOO" should be in comments. This warning is on by default. --WWbbaadd--ffuunnccttiioonn--ccaasstt (C and Objective-C only) Warn when a function call is cast to a non-matching type. For ex- ample, warn if a call to a function returning an integer type is cast to a pointer type. --WWcc9900--cc9999--ccoommppaatt (C and Objective-C only) Warn about features not present in ISO C90, but present in ISO C99. For instance, warn about use of variable length arrays, "long long" type, "bool" type, compound literals, designated initializers, and so on. This option is independent of the standards mode. Warnings are disabled in the expression that follows "__extension__". --WWcc9999--cc1111--ccoommppaatt (C and Objective-C only) Warn about features not present in ISO C99, but present in ISO C11. For instance, warn about use of anonymous structures and unions, "_Atomic" type qualifier, "_Thread_local" storage-class specifier, "_Alignas" specifier, "Alignof" operator, "_Generic" keyword, and so on. This option is independent of the standards mode. Warnings are disabled in the expression that follows "__extension__". --WWcc1111--cc22xx--ccoommppaatt (C and Objective-C only) Warn about features not present in ISO C11, but present in ISO C2X. For instance, warn about omitting the string in "_Static_assert", use of [[[[]]]] syntax for attributes, use of decimal floating-point types, and so on. This option is independent of the standards mode. Warnings are disabled in the expression that follows "__ex- tension__". --WWcc++++--ccoommppaatt (C and Objective-C only) Warn about ISO C constructs that are outside of the common subset of ISO C and ISO C++, e.g. request for implicit conversion from "void *" to a pointer to non-"void" type. --WWcc++++1111--ccoommppaatt (C++ and Objective-C++ only) Warn about C++ constructs whose meaning differs between ISO C++ 1998 and ISO C++ 2011, e.g., identifiers in ISO C++ 1998 that are keywords in ISO C++ 2011. This warning turns on --WWnnaarrrroowwiinngg and is enabled by --WWaallll. --WWcc++++1144--ccoommppaatt (C++ and Objective-C++ only) Warn about C++ constructs whose meaning differs between ISO C++ 2011 and ISO C++ 2014. This warning is enabled by --WWaallll. --WWcc++++1177--ccoommppaatt (C++ and Objective-C++ only) Warn about C++ constructs whose meaning differs between ISO C++ 2014 and ISO C++ 2017. This warning is enabled by --WWaallll. --WWcc++++2200--ccoommppaatt (C++ and Objective-C++ only) Warn about C++ constructs whose meaning differs between ISO C++ 2017 and ISO C++ 2020. This warning is enabled by --WWaallll. --WWnnoo--cc++++1111--eexxtteennssiioonnss (C++ and Objective-C++ only) Do not warn about C++11 constructs in code being compiled using an older C++ standard. Even without this option, some C++11 con- structs will only be diagnosed if --WWppeeddaannttiicc is used. --WWnnoo--cc++++1144--eexxtteennssiioonnss (C++ and Objective-C++ only) Do not warn about C++14 constructs in code being compiled using an older C++ standard. Even without this option, some C++14 con- structs will only be diagnosed if --WWppeeddaannttiicc is used. --WWnnoo--cc++++1177--eexxtteennssiioonnss (C++ and Objective-C++ only) Do not warn about C++17 constructs in code being compiled using an older C++ standard. Even without this option, some C++17 con- structs will only be diagnosed if --WWppeeddaannttiicc is used. --WWnnoo--cc++++2200--eexxtteennssiioonnss (C++ and Objective-C++ only) Do not warn about C++20 constructs in code being compiled using an older C++ standard. Even without this option, some C++20 con- structs will only be diagnosed if --WWppeeddaannttiicc is used. --WWnnoo--cc++++2233--eexxtteennssiioonnss (C++ and Objective-C++ only) Do not warn about C++23 constructs in code being compiled using an older C++ standard. Even without this option, some C++23 con- structs will only be diagnosed if --WWppeeddaannttiicc is used. --WWccaasstt--qquuaall Warn whenever a pointer is cast so as to remove a type qualifier from the target type. For example, warn if a "const char *" is cast to an ordinary "char *". Also warn when making a cast that introduces a type qualifier in an unsafe way. For example, casting "char **" to "const char **" is unsafe, as in this example: /* p is char ** value. */ const char **q = (const char **) p; /* Assignment of readonly string to const char * is OK. */ *q = "string"; /* Now char** pointer points to read-only memory. */ **p = 'b'; --WWccaasstt--aalliiggnn Warn whenever a pointer is cast such that the required alignment of the target is increased. For example, warn if a "char *" is cast to an "int *" on machines where integers can only be accessed at two- or four-byte boundaries. --WWccaasstt--aalliiggnn==ssttrriicctt Warn whenever a pointer is cast such that the required alignment of the target is increased. For example, warn if a "char *" is cast to an "int *" regardless of the target machine. --WWccaasstt--ffuunnccttiioonn--ttyyppee Warn when a function pointer is cast to an incompatible function pointer. In a cast involving function types with a variable argu- ment list only the types of initial arguments that are provided are considered. Any parameter of pointer-type matches any other pointer-type. Any benign differences in integral types are ig- nored, like "int" vs. "long" on ILP32 targets. Likewise type qual- ifiers are ignored. The function type "void (*) (void)" is special and matches everything, which can be used to suppress this warning. In a cast involving pointer to member types this warning warns whenever the type cast is changing the pointer to member type. This warning is enabled by --WWeexxttrraa. --WWwwrriittee--ssttrriinnggss When compiling C, give string constants the type "const char[_l_e_n_g_t_h_]_" so that copying the address of one into a non-"const" "char *" pointer produces a warning. These warnings help you find at compile time code that can try to write into a string constant, but only if you have been very careful about using "const" in dec- larations and prototypes. Otherwise, it is just a nuisance. This is why we did not make --WWaallll request these warnings. When compiling C++, warn about the deprecated conversion from string literals to "char *". This warning is enabled by default for C++ programs. --WWcclloobbbbeerreedd Warn for variables that might be changed by "longjmp" or "vfork". This warning is also enabled by --WWeexxttrraa. --WWccoonnvveerrssiioonn Warn for implicit conversions that may alter a value. This includes conversions between real and integer, like "abs (x)" when "x" is "double"; conversions between signed and unsigned, like "unsigned ui = -1"; and conversions to smaller types, like "sqrtf (M_PI)". Do not warn for explicit casts like "abs ((int) x)" and "ui = (un- signed) -1", or if the value is not changed by the conversion like in "abs (2.0)". Warnings about conversions between signed and un- signed integers can be disabled by using --WWnnoo--ssiiggnn--ccoonnvveerrssiioonn. For C++, also warn for confusing overload resolution for user-de- fined conversions; and conversions that never use a type conversion operator: conversions to "void", the same type, a base class or a reference to them. Warnings about conversions between signed and unsigned integers are disabled by default in C++ unless --WWssiiggnn--ccoonn-- vveerrssiioonn is explicitly enabled. Warnings about conversion from arithmetic on a small type back to that type are only given with --WWaarriitthh--ccoonnvveerrssiioonn. --WWddaanngglliinngg--eellssee Warn about constructions where there may be confusion to which "if" statement an "else" branch belongs. Here is an example of such a case: { if (a) if (b) foo (); else bar (); } In C/C++, every "else" branch belongs to the innermost possible "if" statement, which in this example is "if (b)". This is often not what the programmer expected, as illustrated in the above exam- ple by indentation the programmer chose. When there is the poten- tial for this confusion, GCC issues a warning when this flag is specified. To eliminate the warning, add explicit braces around the innermost "if" statement so there is no way the "else" can be- long to the enclosing "if". The resulting code looks like this: { if (a) { if (b) foo (); else bar (); } } This warning is enabled by --WWppaarreenntthheesseess. --WWddaanngglliinngg--ppooiinntteerr --WWddaanngglliinngg--ppooiinntteerr==_n Warn about uses of pointers (or C++ references) to objects with au- tomatic storage duration after their lifetime has ended. This in- cludes local variables declared in nested blocks, compound literals and other unnamed temporary objects. In addition, warn about stor- ing the address of such objects in escaped pointers. The warning is enabled at all optimization levels but may yield different re- sults with optimization than without. --WWddaanngglliinngg--ppooiinntteerr==11 At level 1 the warning diagnoses only unconditional uses of dangling pointers. For example int f (int c1, int c2, x) { char *p = strchr ((char[]){ c1, c2 }, c3); return p ? *p : 'x'; // warning: dangling pointer to a compound literal } In the following function the store of the address of the local variable "x" in the escaped pointer *p also triggers the warn- ing. void g (int **p) { int x = 7; *p = &x; // warning: storing the address of a local variable in *p } --WWddaanngglliinngg--ppooiinntteerr==22 At level 2, in addition to unconditional uses the warning also diagnoses conditional uses of dangling pointers. For example, because the array _a in the following function is out of scope when the pointer _s that was set to point is used, the warning triggers at this level. void f (char *s) { if (!s) { char a[12] = "tmpname"; s = a; } strcat (s, ".tmp"); // warning: dangling pointer to a may be used ... } --WWddaanngglliinngg--ppooiinntteerr==22 is included in --WWaallll. --WWddaattee--ttiimmee Warn when macros "__TIME__", "__DATE__" or "__TIMESTAMP__" are en- countered as they might prevent bit-wise-identical reproducible compilations. --WWeemmppttyy--bbooddyy Warn if an empty body occurs in an "if", "else" or "do while" statement. This warning is also enabled by --WWeexxttrraa. --WWnnoo--eennddiiff--llaabbeellss Do not warn about stray tokens after "#else" and "#endif". --WWeennuumm--ccoommppaarree Warn about a comparison between values of different enumerated types. In C++ enumerated type mismatches in conditional expres- sions are also diagnosed and the warning is enabled by default. In C this warning is enabled by --WWaallll. --WWeennuumm--ccoonnvveerrssiioonn Warn when a value of enumerated type is implicitly converted to a different enumerated type. This warning is enabled by --WWeexxttrraa in C. --WWjjuummpp--mmiisssseess--iinniitt (C, Objective-C only) Warn if a "goto" statement or a "switch" statement jumps forward across the initialization of a variable, or jumps backward to a la- bel after the variable has been initialized. This only warns about variables that are initialized when they are declared. This warn- ing is only supported for C and Objective-C; in C++ this sort of branch is an error in any case. --WWjjuummpp--mmiisssseess--iinniitt is included in --WWcc++++--ccoommppaatt. It can be disabled with the --WWnnoo--jjuummpp--mmiisssseess--iinniitt option. --WWssiiggnn--ccoommppaarree Warn when a comparison between signed and unsigned values could produce an incorrect result when the signed value is converted to unsigned. In C++, this warning is also enabled by --WWaallll. In C, it is also enabled by --WWeexxttrraa. --WWssiiggnn--ccoonnvveerrssiioonn Warn for implicit conversions that may change the sign of an inte- ger value, like assigning a signed integer expression to an un- signed integer variable. An explicit cast silences the warning. In C, this option is enabled also by --WWccoonnvveerrssiioonn. --WWffllooaatt--ccoonnvveerrssiioonn Warn for implicit conversions that reduce the precision of a real value. This includes conversions from real to integer, and from higher precision real to lower precision real values. This option is also enabled by --WWccoonnvveerrssiioonn. --WWnnoo--ssccaallaarr--ssttoorraaggee--oorrddeerr Do not warn on suspicious constructs involving reverse scalar stor- age order. --WWssiizzeeooff--aarrrraayy--ddiivv Warn about divisions of two sizeof operators when the first one is applied to an array and the divisor does not equal the size of the array element. In such a case, the computation will not yield the number of elements in the array, which is likely what the user in- tended. This warning warns e.g. about int fn () { int arr[10]; return sizeof (arr) / sizeof (short); } This warning is enabled by --WWaallll. --WWssiizzeeooff--ppooiinntteerr--ddiivv Warn for suspicious divisions of two sizeof expressions that divide the pointer size by the element size, which is the usual way to compute the array size but won't work out correctly with pointers. This warning warns e.g. about "sizeof (ptr) / sizeof (ptr[0])" if "ptr" is not an array, but a pointer. This warning is enabled by --WWaallll. --WWssiizzeeooff--ppooiinntteerr--mmeemmaacccceessss Warn for suspicious length parameters to certain string and memory built-in functions if the argument uses "sizeof". This warning triggers for example for "memset (ptr, 0, sizeof (ptr));" if "ptr" is not an array, but a pointer, and suggests a possible fix, or about "memcpy (&foo, ptr, sizeof (&foo));". --WWssiizzeeooff--ppooiinntteerr--mmeemmaacccceessss also warns about calls to bounded string copy functions like "strncat" or "strncpy" that specify as the bound a "sizeof" expression of the source array. For example, in the following function the call to "strncat" specifies the size of the source string as the bound. That is almost certainly a mistake and so the call is diagnosed. void make_file (const char *name) { char path[PATH_MAX]; strncpy (path, name, sizeof path - 1); strncat (path, ".text", sizeof ".text"); ... } The --WWssiizzeeooff--ppooiinntteerr--mmeemmaacccceessss option is enabled by --WWaallll. --WWnnoo--ssiizzeeooff--aarrrraayy--aarrgguummeenntt Do not warn when the "sizeof" operator is applied to a parameter that is declared as an array in a function definition. This warn- ing is enabled by default for C and C++ programs. --WWmmeemmsseett--eelltt--ssiizzee Warn for suspicious calls to the "memset" built-in function, if the first argument references an array, and the third argument is a number equal to the number of elements, but not equal to the size of the array in memory. This indicates that the user has omitted a multiplication by the element size. This warning is enabled by --WWaallll. --WWmmeemmsseett--ttrraannssppoosseedd--aarrggss Warn for suspicious calls to the "memset" built-in function where the second argument is not zero and the third argument is zero. For example, the call "memset (buf, sizeof buf, 0)" is diagnosed because "memset (buf, 0, sizeof buf)" was meant instead. The diag- nostic is only emitted if the third argument is a literal zero. Otherwise, if it is an expression that is folded to zero, or a cast of zero to some type, it is far less likely that the arguments have been mistakenly transposed and no warning is emitted. This warning is enabled by --WWaallll. --WWaaddddrreessss Warn about suspicious uses of address expressions. These include comparing the address of a function or a declared object to the null pointer constant such as in void f (void); void g (void) { if (!func) // warning: expression evaluates to false abort (); } comparisons of a pointer to a string literal, such as in void f (const char *x) { if (x == "abc") // warning: expression evaluates to false puts ("equal"); } and tests of the results of pointer addition or subtraction for equality to null, such as in void f (const int *p, int i) { return p + i == NULL; } Such uses typically indicate a programmer error: the address of most functions and objects necessarily evaluates to true (the ex- ception are weak symbols), so their use in a conditional might in- dicate missing parentheses in a function call or a missing derefer- ence in an array expression. The subset of the warning for object pointers can be suppressed by casting the pointer operand to an in- teger type such as "inptr_t" or "uinptr_t". Comparisons against string literals result in unspecified behavior and are not porta- ble, and suggest the intent was to call "strcmp". The warning is suppressed if the suspicious expression is the result of macro ex- pansion. --WWaaddddrreessss warning is enabled by --WWaallll. --WWnnoo--aaddddrreessss--ooff--ppaacckkeedd--mmeemmbbeerr Do not warn when the address of packed member of struct or union is taken, which usually results in an unaligned pointer value. This is enabled by default. --WWllooggiiccaall--oopp Warn about suspicious uses of logical operators in expressions. This includes using logical operators in contexts where a bit-wise operator is likely to be expected. Also warns when the operands of a logical operator are the same: extern int a; if (a < 0 && a < 0) { ... } --WWllooggiiccaall--nnoott--ppaarreenntthheesseess Warn about logical not used on the left hand side operand of a com- parison. This option does not warn if the right operand is consid- ered to be a boolean expression. Its purpose is to detect suspi- cious code like the following: int a; ... if (!a > 1) { ... } It is possible to suppress the warning by wrapping the LHS into parentheses: if ((!a) > 1) { ... } This warning is enabled by --WWaallll. --WWaaggggrreeggaattee--rreettuurrnn Warn if any functions that return structures or unions are defined or called. (In languages where you can return an array, this also elicits a warning.) --WWnnoo--aaggggrreessssiivvee--lloooopp--ooppttiimmiizzaattiioonnss Warn if in a loop with constant number of iterations the compiler detects undefined behavior in some statement during one or more of the iterations. --WWnnoo--aattttrriibbuutteess Do not warn if an unexpected "__attribute__" is used, such as un- recognized attributes, function attributes applied to variables, etc. This does not stop errors for incorrect use of supported at- tributes. Additionally, using --WWnnoo--aattttrriibbuutteess==, it is possible to suppress warnings about unknown scoped attributes (in C++11 and C2X). For example, --WWnnoo--aattttrriibbuutteess==vveennddoorr::::aattttrr disables warning about the following declaration: [[vendor::attr]] void f(); It is also possible to disable warning about all attributes in a namespace using --WWnnoo--aattttrriibbuutteess==vveennddoorr:::: which prevents warning about both of these declarations: [[vendor::safe]] void f(); [[vendor::unsafe]] void f2(); Note that --WWnnoo--aattttrriibbuutteess== does not imply --WWnnoo--aattttrriibbuutteess. --WWnnoo--bbuuiillttiinn--ddeeccllaarraattiioonn--mmiissmmaattcchh Warn if a built-in function is declared with an incompatible signa- ture or as a non-function, or when a built-in function declared with a type that does not include a prototype is called with argu- ments whose promoted types do not match those expected by the func- tion. When --WWeexxttrraa is specified, also warn when a built-in func- tion that takes arguments is declared without a prototype. The --WWbbuuiillttiinn--ddeeccllaarraattiioonn--mmiissmmaattcchh warning is enabled by default. To avoid the warning include the appropriate header to bring the pro- totypes of built-in functions into scope. For example, the call to "memset" below is diagnosed by the warning because the function expects a value of type "size_t" as its argu- ment but the type of 32 is "int". With --WWeexxttrraa, the declaration of the function is diagnosed as well. extern void* memset (); void f (void *d) { memset (d, '\0', 32); } --WWnnoo--bbuuiillttiinn--mmaaccrroo--rreeddeeffiinneedd Do not warn if certain built-in macros are redefined. This sup- presses warnings for redefinition of "__TIMESTAMP__", "__TIME__", "__DATE__", "__FILE__", and "__BASE_FILE__". --WWssttrriicctt--pprroottoottyyppeess (C and Objective-C only) Warn if a function is declared or defined without specifying the argument types. (An old-style function definition is permitted without a warning if preceded by a declaration that specifies the argument types.) --WWoolldd--ssttyyllee--ddeeccllaarraattiioonn (C and Objective-C only) Warn for obsolescent usages, according to the C Standard, in a dec- laration. For example, warn if storage-class specifiers like "static" are not the first things in a declaration. This warning is also enabled by --WWeexxttrraa. --WWoolldd--ssttyyllee--ddeeffiinniittiioonn (C and Objective-C only) Warn if an old-style function definition is used. A warning is given even if there is a previous prototype. A definition using (()) is not considered an old-style definition in C2X mode, because it is equivalent to ((vvooiidd)) in that case, but is considered an old- style definition for older standards. --WWmmiissssiinngg--ppaarraammeetteerr--ttyyppee (C and Objective-C only) A function parameter is declared without a type specifier in K&R-style functions: void foo(bar) { } This warning is also enabled by --WWeexxttrraa. --WWmmiissssiinngg--pprroottoottyyppeess (C and Objective-C only) Warn if a global function is defined without a previous prototype declaration. This warning is issued even if the definition itself provides a prototype. Use this option to detect global functions that do not have a matching prototype declaration in a header file. This option is not valid for C++ because all function declarations provide prototypes and a non-matching declaration declares an over- load rather than conflict with an earlier declaration. Use --WWmmiissss-- iinngg--ddeeccllaarraattiioonnss to detect missing declarations in C++. --WWmmiissssiinngg--ddeeccllaarraattiioonnss Warn if a global function is defined without a previous declara- tion. Do so even if the definition itself provides a prototype. Use this option to detect global functions that are not declared in header files. In C, no warnings are issued for functions with pre- vious non-prototype declarations; use --WWmmiissssiinngg--pprroottoottyyppeess to de- tect missing prototypes. In C++, no warnings are issued for func- tion templates, or for inline functions, or for functions in anony- mous namespaces. --WWmmiissssiinngg--ffiieelldd--iinniittiiaalliizzeerrss Warn if a structure's initializer has some fields missing. For ex- ample, the following code causes such a warning, because "x.h" is implicitly zero: struct s { int f, g, h; }; struct s x = { 3, 4 }; This option does not warn about designated initializers, so the following modification does not trigger a warning: struct s { int f, g, h; }; struct s x = { .f = 3, .g = 4 }; In C this option does not warn about the universal zero initializer {{ 00 }}: struct s { int f, g, h; }; struct s x = { 0 }; Likewise, in C++ this option does not warn about the empty { } ini- tializer, for example: struct s { int f, g, h; }; s x = { }; This warning is included in --WWeexxttrraa. To get other --WWeexxttrraa warnings without this one, use --WWeexxttrraa --WWnnoo--mmiissssiinngg--ffiieelldd--iinniittiiaalliizzeerrss. --WWnnoo--mmiissssiinngg--rreeqquuiirreess By default, the compiler warns about a concept-id appearing as a C++20 simple-requirement: bool satisfied = requires { C }; Here ssaattiissffiieedd will be true if CC<> is a valid expression, which it is for all T. Presumably the user meant to write bool satisfied = requires { requires C }; so ssaattiissffiieedd is only true if concept CC is satisfied for type TT. This warning can be disabled with --WWnnoo--mmiissssiinngg--rreeqquuiirreess. --WWnnoo--mmiissssiinngg--tteemmppllaattee--kkeeyywwoorrdd The member access tokens ., -> and :: must be followed by the "tem- plate" keyword if the parent object is dependent and the member be- ing named is a template. template void DoStuff (X x) { x.template DoSomeOtherStuff(); // Good. x.DoMoreStuff(); // Warning, x is dependent. } In rare cases it is possible to get false positives. To silence this, wrap the expression in parentheses. For example, the follow- ing is treated as a template, even where m and N are integers: void NotATemplate (my_class t) { int N = 5; bool test = t.m < N > (0); // Treated as a template. test = (t.m < N) > (0); // Same meaning, but not treated as a template. } This warning can be disabled with --WWnnoo--mmiissssiinngg--tteemmppllaattee--kkeeyywwoorrdd. --WWnnoo--mmuullttiicchhaarr Do not warn if a multicharacter constant (''FFOOOOFF'') is used. Usually they indicate a typo in the user's code, as they have implementa- tion-defined values, and should not be used in portable code. --WWnnoorrmmaalliizzeedd==[nnoonnee|iidd|nnffcc|nnffkkcc] In ISO C and ISO C++, two identifiers are different if they are different sequences of characters. However, sometimes when charac- ters outside the basic ASCII character set are used, you can have two different character sequences that look the same. To avoid confusion, the ISO 10646 standard sets out some _n_o_r_m_a_l_i_z_a_t_i_o_n _r_u_l_e_s which when applied ensure that two sequences that look the same are turned into the same sequence. GCC can warn you if you are using identifiers that have not been normalized; this option controls that warning. There are four levels of warning supported by GCC. The default is --WWnnoorrmmaalliizzeedd==nnffcc, which warns about any identifier that is not in the ISO 10646 "C" normalized form, _N_F_C. NFC is the recommended form for most uses. It is equivalent to --WWnnoorrmmaalliizzeedd. Unfortunately, there are some characters allowed in identifiers by ISO C and ISO C++ that, when turned into NFC, are not allowed in identifiers. That is, there's no way to use these symbols in por- table ISO C or C++ and have all your identifiers in NFC. --WWnnoorrmmaall-- iizzeedd==iidd suppresses the warning for these characters. It is hoped that future versions of the standards involved will correct this, which is why this option is not the default. You can switch the warning off for all characters by writing --WWnnoorr-- mmaalliizzeedd==nnoonnee or --WWnnoo--nnoorrmmaalliizzeedd. You should only do this if you are using some other normalization scheme (like "D"), because oth- erwise you can easily create bugs that are literally impossible to see. Some characters in ISO 10646 have distinct meanings but look iden- tical in some fonts or display methodologies, especially once for- matting has been applied. For instance "\u207F", "SUPERSCRIPT LATIN SMALL LETTER N", displays just like a regular "n" that has been placed in a superscript. ISO 10646 defines the _N_F_K_C normal- ization scheme to convert all these into a standard form as well, and GCC warns if your code is not in NFKC if you use --WWnnoorrmmaall-- iizzeedd==nnffkkcc. This warning is comparable to warning about every iden- tifier that contains the letter O because it might be confused with the digit 0, and so is not the default, but may be useful as a lo- cal coding convention if the programming environment cannot be fixed to display these characters distinctly. --WWnnoo--aattttrriibbuuttee--wwaarrnniinngg Do not warn about usage of functions declared with "warning" attri- bute. By default, this warning is enabled. --WWnnoo--aattttrriibbuuttee--wwaarrnniinngg can be used to disable the warning or --WWnnoo--eerrrroorr==aattttrriibbuuttee--wwaarrnniinngg can be used to disable the error when compiled with --WWeerrrroorr flag. --WWnnoo--ddeepprreeccaatteedd Do not warn about usage of deprecated features. --WWnnoo--ddeepprreeccaatteedd--ddeeccllaarraattiioonnss Do not warn about uses of functions, variables, and types marked as deprecated by using the "deprecated" attribute. --WWnnoo--oovveerrffllooww Do not warn about compile-time overflow in constant expressions. --WWnnoo--ooddrr Warn about One Definition Rule violations during link-time opti- mization. Enabled by default. --WWooppeennaacccc--ppaarraalllleelliissmm Warn about potentially suboptimal choices related to OpenACC paral- lelism. --WWooppeennmmpp--ssiimmdd Warn if the vectorizer cost model overrides the OpenMP simd direc- tive set by user. The --ffssiimmdd--ccoosstt--mmooddeell==uunnlliimmiitteedd option can be used to relax the cost model. --WWoovveerrrriiddee--iinniitt (C and Objective-C only) Warn if an initialized field without side effects is overridden when using designated initializers. This warning is included in --WWeexxttrraa. To get other --WWeexxttrraa warnings without this one, use --WWeexxttrraa --WWnnoo--oovveerrrriiddee--iinniitt. --WWnnoo--oovveerrrriiddee--iinniitt--ssiiddee--eeffffeeccttss (C and Objective-C only) Do not warn if an initialized field with side effects is overridden when using designated initializers. This warning is enabled by de- fault. --WWppaacckkeedd Warn if a structure is given the packed attribute, but the packed attribute has no effect on the layout or size of the structure. Such structures may be mis-aligned for little benefit. For in- stance, in this code, the variable "f.x" in "struct bar" is mis- aligned even though "struct bar" does not itself have the packed attribute: struct foo { int x; char a, b, c, d; } __attribute__((packed)); struct bar { char z; struct foo f; }; --WWnnooppaacckkeedd--bbiittffiieelldd--ccoommppaatt The 4.1, 4.2 and 4.3 series of GCC ignore the "packed" attribute on bit-fields of type "char". This was fixed in GCC 4.4 but the change can lead to differences in the structure layout. GCC in- forms you when the offset of such a field has changed in GCC 4.4. For example there is no longer a 4-bit padding between field "a" and "b" in this structure: struct foo { char a:4; char b:8; } __attribute__ ((packed)); This warning is enabled by default. Use --WWnnoo--ppaacckkeedd--bbiittffiieelldd--ccoomm-- ppaatt to disable this warning. --WWppaacckkeedd--nnoott--aalliiggnneedd (C, C++, Objective-C and Objective-C++ only) Warn if a structure field with explicitly specified alignment in a packed struct or union is misaligned. For example, a warning will be issued on "struct S", like, "warning: alignment 1 of 'struct S' is less than 8", in this code: struct __attribute__ ((aligned (8))) S8 { char a[8]; }; struct __attribute__ ((packed)) S { struct S8 s8; }; This warning is enabled by --WWaallll. --WWppaaddddeedd Warn if padding is included in a structure, either to align an ele- ment of the structure or to align the whole structure. Sometimes when this happens it is possible to rearrange the fields of the structure to reduce the padding and so make the structure smaller. --WWrreedduunnddaanntt--ddeeccllss Warn if anything is declared more than once in the same scope, even in cases where multiple declaration is valid and changes nothing. --WWrreessttrriicctt Warn when an object referenced by a "restrict"-qualified parameter (or, in C++, a "__restrict"-qualified parameter) is aliased by an- other argument, or when copies between such objects overlap. For example, the call to the "strcpy" function below attempts to trun- cate the string by replacing its initial characters with the last four. However, because the call writes the terminating NUL into "a[4]", the copies overlap and the call is diagnosed. void foo (void) { char a[] = "abcd1234"; strcpy (a, a + 4); ... } The --WWrreessttrriicctt option detects some instances of simple overlap even without optimization but works best at --OO22 and above. It is in- cluded in --WWaallll. --WWnneesstteedd--eexxtteerrnnss (C and Objective-C only) Warn if an "extern" declaration is encountered within a function. --WWiinnlliinnee Warn if a function that is declared as inline cannot be inlined. Even with this option, the compiler does not warn about failures to inline functions declared in system headers. The compiler uses a variety of heuristics to determine whether or not to inline a function. For example, the compiler takes into ac- count the size of the function being inlined and the amount of in- lining that has already been done in the current function. There- fore, seemingly insignificant changes in the source program can cause the warnings produced by --WWiinnlliinnee to appear or disappear. --WWiinntteerrffeerreennccee--ssiizzee Warn about use of C++17 "std::hardware_destructive_interfer- ence_size" without specifying its value with ----ppaarraamm ddeessttrruuccttiivvee-- iinntteerrffeerreennccee--ssiizzee. Also warn about questionable values for that option. This variable is intended to be used for controlling class layout, to avoid false sharing in concurrent code: struct independent_fields { alignas(std::hardware_destructive_interference_size) std::atomic one; alignas(std::hardware_destructive_interference_size) std::atomic two; }; Here oonnee and ttwwoo are intended to be far enough apart that stores to one won't require accesses to the other to reload the cache line. By default, ----ppaarraamm ddeessttrruuccttiivvee--iinntteerrffeerreennccee--ssiizzee and ----ppaarraamm ccoonn-- ssttrruuccttiivvee--iinntteerrffeerreennccee--ssiizzee are set based on the current --mmttuunnee op- tion, typically to the L1 cache line size for the particular target CPU, sometimes to a range if tuning for a generic target. So all translation units that depend on ABI compatibility for the use of these variables must be compiled with the same --mmttuunnee (or --mmccppuu). If ABI stability is important, such as if the use is in a header for a library, you should probably not use the hardware interfer- ence size variables at all. Alternatively, you can force a partic- ular value with ----ppaarraamm. If you are confident that your use of the variable does not affect ABI outside a single build of your project, you can turn off the warning with --WWnnoo--iinntteerrffeerreennccee--ssiizzee. --WWiinntt--iinn--bbooooll--ccoonntteexxtt Warn for suspicious use of integer values where boolean values are expected, such as conditional expressions (?:) using non-boolean integer constants in boolean context, like "if (a <= b ? 2 : 3)". Or left shifting of signed integers in boolean context, like "for (a = 0; 1 << a; a++);". Likewise for all kinds of multiplications regardless of the data type. This warning is enabled by --WWaallll. --WWnnoo--iinntt--ttoo--ppooiinntteerr--ccaasstt Suppress warnings from casts to pointer type of an integer of a different size. In C++, casting to a pointer type of smaller size is an error. WWiinntt--ttoo--ppooiinntteerr--ccaasstt is enabled by default. --WWnnoo--ppooiinntteerr--ttoo--iinntt--ccaasstt (C and Objective-C only) Suppress warnings from casts from a pointer to an integer type of a different size. --WWiinnvvaalliidd--ppcchh Warn if a precompiled header is found in the search path but cannot be used. --WWlloonngg--lloonngg Warn if "long long" type is used. This is enabled by either --WWppeeddaannttiicc or --WWttrraaddiittiioonnaall in ISO C90 and C++98 modes. To inhibit the warning messages, use --WWnnoo--lloonngg--lloonngg. --WWvvaarriiaaddiicc--mmaaccrrooss Warn if variadic macros are used in ISO C90 mode, or if the GNU al- ternate syntax is used in ISO C99 mode. This is enabled by either --WWppeeddaannttiicc or --WWttrraaddiittiioonnaall. To inhibit the warning messages, use --WWnnoo--vvaarriiaaddiicc--mmaaccrrooss. --WWnnoo--vvaarraarrggss Do not warn upon questionable usage of the macros used to handle variable arguments like "va_start". These warnings are enabled by default. --WWvveeccttoorr--ooppeerraattiioonn--ppeerrffoorrmmaannccee Warn if vector operation is not implemented via SIMD capabilities of the architecture. Mainly useful for the performance tuning. Vector operation can be implemented "piecewise", which means that the scalar operation is performed on every vector element; "in par- allel", which means that the vector operation is implemented using scalars of wider type, which normally is more performance effi- cient; and "as a single scalar", which means that vector fits into a scalar type. --WWvvllaa Warn if a variable-length array is used in the code. --WWnnoo--vvllaa pre- vents the --WWppeeddaannttiicc warning of the variable-length array. --WWvvllaa--llaarrggeerr--tthhaann==_b_y_t_e_-_s_i_z_e If this option is used, the compiler warns for declarations of variable-length arrays whose size is either unbounded, or bounded by an argument that allows the array size to exceed _b_y_t_e_-_s_i_z_e bytes. This is similar to how --WWaallllooccaa--llaarrggeerr--tthhaann==_b_y_t_e_-_s_i_z_e works, but with variable-length arrays. Note that GCC may optimize small variable-length arrays of a known value into plain arrays, so this warning may not get triggered for such arrays. --WWvvllaa--llaarrggeerr--tthhaann==PPTTRRDDIIFFFF__MMAAXX is enabled by default but is typi- cally only effective when --ffttrreeee--vvrrpp is active (default for --OO22 and above). See also --WWaallllooccaa--llaarrggeerr--tthhaann==_b_y_t_e_-_s_i_z_e. --WWnnoo--vvllaa--llaarrggeerr--tthhaann Disable --WWvvllaa--llaarrggeerr--tthhaann== warnings. The option is equivalent to --WWvvllaa--llaarrggeerr--tthhaann==SSIIZZEE__MMAAXX or larger. --WWvvllaa--ppaarraammeetteerr Warn about redeclarations of functions involving arguments of Vari- able Length Array types of inconsistent kinds or forms, and enable the detection of out-of-bounds accesses to such parameters by warn- ings such as --WWaarrrraayy--bboouunnddss. If the first function declaration uses the VLA form the bound spec- ified in the array is assumed to be the minimum number of elements expected to be provided in calls to the function and the maximum number of elements accessed by it. Failing to provide arguments of sufficient size or accessing more than the maximum number of ele- ments may be diagnosed. For example, the warning triggers for the following redeclarations because the first one allows an array of any size to be passed to "f" while the second one specifies that the array argument must have at least "n" elements. In addition, calling "f" with the as- sociated VLA bound parameter in excess of the actual VLA bound triggers a warning as well. void f (int n, int[n]); void f (int, int[]); // warning: argument 2 previously declared as a VLA void g (int n) { if (n > 4) return; int a[n]; f (sizeof a, a); // warning: access to a by f may be out of bounds ... } --WWvvllaa--ppaarraammeetteerr is included in --WWaallll. The --WWaarrrraayy--ppaarraammeetteerr option triggers warnings for similar problems involving ordinary array ar- guments. --WWvvoollaattiillee--rreeggiisstteerr--vvaarr Warn if a register variable is declared volatile. The volatile modifier does not inhibit all optimizations that may eliminate reads and/or writes to register variables. This warning is enabled by --WWaallll. --WWddiissaabblleedd--ooppttiimmiizzaattiioonn Warn if a requested optimization pass is disabled. This warning does not generally indicate that there is anything wrong with your code; it merely indicates that GCC's optimizers are unable to han- dle the code effectively. Often, the problem is that your code is too big or too complex; GCC refuses to optimize programs when the optimization itself is likely to take inordinate amounts of time. --WWppooiinntteerr--ssiiggnn (C and Objective-C only) Warn for pointer argument passing or assignment with different signedness. This option is only supported for C and Objective-C. It is implied by --WWaallll and by --WWppeeddaannttiicc, which can be disabled with --WWnnoo--ppooiinntteerr--ssiiggnn. --WWssttaacckk--pprrootteeccttoorr This option is only active when --ffssttaacckk--pprrootteeccttoorr is active. It warns about functions that are not protected against stack smash- ing. --WWoovveerrlleennggtthh--ssttrriinnggss Warn about string constants that are longer than the "minimum maxi- mum" length specified in the C standard. Modern compilers gener- ally allow string constants that are much longer than the stan- dard's minimum limit, but very portable programs should avoid using longer strings. The limit applies _a_f_t_e_r string constant concatenation, and does not count the trailing NUL. In C90, the limit was 509 characters; in C99, it was raised to 4095. C++98 does not specify a normative minimum maximum, so we do not diagnose overlength strings in C++. This option is implied by --WWppeeddaannttiicc, and can be disabled with --WWnnoo--oovveerrlleennggtthh--ssttrriinnggss. --WWuunnssuuffffiixxeedd--ffllooaatt--ccoonnssttaannttss (C and Objective-C only) Issue a warning for any floating constant that does not have a suf- fix. When used together with --WWssyysstteemm--hheeaaddeerrss it warns about such constants in system header files. This can be useful when prepar- ing code to use with the "FLOAT_CONST_DECIMAL64" pragma from the decimal floating-point extension to C99. --WWnnoo--llttoo--ttyyppee--mmiissmmaattcchh During the link-time optimization, do not warn about type mis- matches in global declarations from different compilation units. Requires --ffllttoo to be enabled. Enabled by default. --WWnnoo--ddeessiiggnnaatteedd--iinniitt (C and Objective-C only) Suppress warnings when a positional initializer is used to initial- ize a structure that has been marked with the "designated_init" at- tribute. OOppttiioonnss TThhaatt CCoonnttrrooll SSttaattiicc AAnnaallyyssiiss --ffaannaallyyzzeerr This option enables an static analysis of program flow which looks for "interesting" interprocedural paths through the code, and is- sues warnings for problems found on them. This analysis is much more expensive than other GCC warnings. Enabling this option effectively enables the following warnings: --WWaannaallyyzzeerr--ddoouubbllee--ffcclloossee --WWaannaallyyzzeerr--ddoouubbllee--ffrreeee --WWaannaallyyzzeerr--eexxppoo-- ssuurree--tthhrroouugghh--oouuttppuutt--ffiillee --WWaannaallyyzzeerr--ffiillee--lleeaakk --WWaannaa-- llyyzzeerr--ffrreeee--ooff--nnoonn--hheeaapp --WWaannaallyyzzeerr--mmaalllloocc--lleeaakk --WWaannaallyyzzeerr--mmiissmmaattcchh-- iinngg--ddeeaallllooccaattiioonn --WWaannaallyyzzeerr--nnuullll--aarrgguummeenntt --WWaannaallyyzzeerr--nnuullll--ddeerreeffeerr-- eennccee --WWaannaallyyzzeerr--ppoossssiibbllee--nnuullll--aarrgguummeenntt --WWaannaallyyzzeerr--ppoossssii-- bbllee--nnuullll--ddeerreeffeerreennccee --WWaannaallyyzzeerr--sshhiifftt--ccoouunntt--nneeggaattiivvee --WWaannaa-- llyyzzeerr--sshhiifftt--ccoouunntt--oovveerrffllooww --WWaannaallyyzzeerr--ssttaallee--sseettjjmmpp--bbuuffffeerr --WWaannaa-- llyyzzeerr--uunnssaaffee--ccaallll--wwiitthhiinn--ssiiggnnaall--hhaannddlleerr --WWaannaallyyzzeerr--uussee--aafftteerr--ffrreeee --WWaannaallyyzzeerr--uussee--ooff--ppooiinntteerr--iinn--ssttaallee--ssttaacckk--ffrraammee --WWaannaa-- llyyzzeerr--uussee--ooff--uunniinniittiiaalliizzeedd--vvaalluuee --WWaannaallyyzzeerr--wwrriittee--ttoo--ccoonnsstt --WWaannaa-- llyyzzeerr--wwrriittee--ttoo--ssttrriinngg--lliitteerraall This option is only available if GCC was configured with analyzer support enabled. --WWaannaallyyzzeerr--ttoooo--ccoommpplleexx If --ffaannaallyyzzeerr is enabled, the analyzer uses various heuristics to attempt to explore the control flow and data flow in the program, but these can be defeated by sufficiently complicated code. By default, the analysis silently stops if the code is too compli- cated for the analyzer to fully explore and it reaches an internal limit. The --WWaannaallyyzzeerr--ttoooo--ccoommpplleexx option warns if this occurs. --WWnnoo--aannaallyyzzeerr--ddoouubbllee--ffcclloossee This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--ddoouubbllee--ffcclloossee to disable it. This diagnostic warns for paths through the code in which a "FILE *" can have "fclose" called on it more than once. --WWnnoo--aannaallyyzzeerr--ddoouubbllee--ffrreeee This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--ddoouubbllee--ffrreeee to disable it. This diagnostic warns for paths through the code in which a pointer can have a deallocator called on it more than once, either "free", or a deallocator referenced by attribute "malloc". --WWnnoo--aannaallyyzzeerr--eexxppoossuurree--tthhrroouugghh--oouuttppuutt--ffiillee This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--eexxppoossuurree--tthhrroouugghh--oouuttppuutt--ffiillee to disable it. This diagnostic warns for paths through the code in which a secu- rity-sensitive value is written to an output file (such as writing a password to a log file). --WWnnoo--aannaallyyzzeerr--ffiillee--lleeaakk This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--ffiillee--lleeaakk to disable it. This diagnostic warns for paths through the code in which a "" "FILE *" stream object is leaked. --WWnnoo--aannaallyyzzeerr--ffrreeee--ooff--nnoonn--hheeaapp This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--ffrreeee--ooff--nnoonn--hheeaapp to disable it. This diagnostic warns for paths through the code in which "free" is called on a non-heap pointer (e.g. an on-stack buffer, or a global). --WWnnoo--aannaallyyzzeerr--mmaalllloocc--lleeaakk This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--mmaalllloocc--lleeaakk to disable it. This diagnostic warns for paths through the code in which a pointer allocated via an allocator is leaked: either "malloc", or a func- tion marked with attribute "malloc". --WWnnoo--aannaallyyzzeerr--mmiissmmaattcchhiinngg--ddeeaallllooccaattiioonn This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--mmiissmmaattcchhiinngg--ddeeaallllooccaattiioonn to disable it. This diagnostic warns for paths through the code in which the wrong deallocation function is called on a pointer value, based on which function was used to allocate the pointer value. The diagnostic will warn about mismatches between "free", scalar "delete" and vec- tor "delete[]", and those marked as allocator/deallocator pairs us- ing attribute "malloc". --WWnnoo--aannaallyyzzeerr--ppoossssiibbllee--nnuullll--aarrgguummeenntt This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--ppoossssiibbllee--nnuullll--aarrgguummeenntt to disable it. This diagnostic warns for paths through the code in which a possi- bly-NULL value is passed to a function argument marked with "__at- tribute__((nonnull))" as requiring a non-NULL value. --WWnnoo--aannaallyyzzeerr--ppoossssiibbllee--nnuullll--ddeerreeffeerreennccee This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--ppoossssiibbllee--nnuullll--ddeerreeffeerreennccee to disable it. This diagnostic warns for paths through the code in which a possi- bly-NULL value is dereferenced. --WWnnoo--aannaallyyzzeerr--nnuullll--aarrgguummeenntt This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--nnuullll--aarrgguummeenntt to disable it. This diagnostic warns for paths through the code in which a value known to be NULL is passed to a function argument marked with "__attribute__((nonnull))" as requiring a non-NULL value. --WWnnoo--aannaallyyzzeerr--nnuullll--ddeerreeffeerreennccee This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--nnuullll--ddeerreeffeerreennccee to disable it. This diagnostic warns for paths through the code in which a value known to be NULL is dereferenced. --WWnnoo--aannaallyyzzeerr--sshhiifftt--ccoouunntt--nneeggaattiivvee This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--sshhiifftt--ccoouunntt--nneeggaattiivvee to disable it. This diagnostic warns for paths through the code in which a shift is attempted with a negative count. It is analogous to the --WWsshhiifftt--ccoouunntt--nneeggaattiivvee diagnostic implemented in the C/C++ front ends, but is implemented based on analyzing interprocedural paths, rather than merely parsing the syntax tree. However, the analyzer does not prioritize detection of such paths, so false negatives are more likely relative to other warnings. --WWnnoo--aannaallyyzzeerr--sshhiifftt--ccoouunntt--oovveerrffllooww This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--sshhiifftt--ccoouunntt--oovveerrffllooww to disable it. This diagnostic warns for paths through the code in which a shift is attempted with a count greater than or equal to the precision of the operand's type. It is analogous to the --WWsshhiifftt--ccoouunntt--oovveerrffllooww diagnostic implemented in the C/C++ front ends, but is implemented based on analyzing interprocedural paths, rather than merely pars- ing the syntax tree. However, the analyzer does not prioritize de- tection of such paths, so false negatives are more likely relative to other warnings. --WWnnoo--aannaallyyzzeerr--ssttaallee--sseettjjmmpp--bbuuffffeerr This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--ssttaallee--sseettjjmmpp--bbuuffffeerr to disable it. This diagnostic warns for paths through the code in which "longjmp" is called to rewind to a "jmp_buf" relating to a "setjmp" call in a function that has returned. When "setjmp" is called on a "jmp_buf" to record a rewind location, it records the stack frame. The stack frame becomes invalid when the function containing the "setjmp" call returns. Attempting to rewind to it via "longjmp" would reference a stack frame that no longer exists, and likely lead to a crash (or worse). --WWnnoo--aannaallyyzzeerr--ttaaiinntteedd--aallllooccaattiioonn--ssiizzee This warning requires both --ffaannaallyyzzeerr and --ffaannaallyyzzeerr--cchheecckkeerr==ttaaiinntt to enable it; use --WWnnoo--aannaallyyzzeerr--ttaaiinntteedd--aallllooccaattiioonn--ssiizzee to disable it. This diagnostic warns for paths through the code in which a value that could be under an attacker's control is used as the size of an allocation without being sanitized, so that an attacker could in- ject an excessively large allocation and potentially cause a denial of service attack. See @url{https://cwe.mitre.org/data/definitions/789.html, CWE-789: Memory Allocation with Excessive Size Value}. --WWnnoo--aannaallyyzzeerr--ttaaiinntteedd--aarrrraayy--iinnddeexx This warning requires both --ffaannaallyyzzeerr and --ffaannaallyyzzeerr--cchheecckkeerr==ttaaiinntt to enable it; use --WWnnoo--aannaallyyzzeerr--ttaaiinntteedd--aarrrraayy--iinnddeexx to disable it. This diagnostic warns for paths through the code in which a value that could be under an attacker's control is used as the index of an array access without being sanitized, so that an attacker could inject an out-of-bounds access. See @url{https://cwe.mitre.org/data/definitions/129.html, CWE-129: Improper Validation of Array Index}. --WWnnoo--aannaallyyzzeerr--ttaaiinntteedd--ddiivviissoorr This warning requires both --ffaannaallyyzzeerr and --ffaannaallyyzzeerr--cchheecckkeerr==ttaaiinntt to enable it; use --WWnnoo--aannaallyyzzeerr--ttaaiinntteedd--ddiivviissoorr to disable it. This diagnostic warns for paths through the code in which a value that could be under an attacker's control is used as the divisor in a division or modulus operation without being sanitized, so that an attacker could inject a division-by-zero. --WWnnoo--aannaallyyzzeerr--ttaaiinntteedd--ooffffsseett This warning requires both --ffaannaallyyzzeerr and --ffaannaallyyzzeerr--cchheecckkeerr==ttaaiinntt to enable it; use --WWnnoo--aannaallyyzzeerr--ttaaiinntteedd--ooffffsseett to disable it. This diagnostic warns for paths through the code in which a value that could be under an attacker's control is used as a pointer off- set without being sanitized, so that an attacker could inject an out-of-bounds access. See @url{https://cwe.mitre.org/data/definitions/823.html, CWE-823: Use of Out-of-range Pointer Offset}. --WWnnoo--aannaallyyzzeerr--ttaaiinntteedd--ssiizzee This warning requires both --ffaannaallyyzzeerr and --ffaannaallyyzzeerr--cchheecckkeerr==ttaaiinntt to enable it; use --WWnnoo--aannaallyyzzeerr--ttaaiinntteedd--ssiizzee to disable it. This diagnostic warns for paths through the code in which a value that could be under an attacker's control is used as the size of an operation such as "memset" without being sanitized, so that an at- tacker could inject an out-of-bounds access. --WWnnoo--aannaallyyzzeerr--uunnssaaffee--ccaallll--wwiitthhiinn--ssiiggnnaall--hhaannddlleerr This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--uunnssaaffee--ccaallll--wwiitthhiinn--ssiiggnnaall--hhaannddlleerr to disable it. This diagnostic warns for paths through the code in which a func- tion known to be async-signal-unsafe (such as "fprintf") is called from a signal handler. --WWnnoo--aannaallyyzzeerr--uussee--aafftteerr--ffrreeee This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--uussee--aafftteerr--ffrreeee to disable it. This diagnostic warns for paths through the code in which a pointer is used after a deallocator is called on it: either "free", or a deallocator referenced by attribute "malloc". --WWnnoo--aannaallyyzzeerr--uussee--ooff--ppooiinntteerr--iinn--ssttaallee--ssttaacckk--ffrraammee This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--uussee--ooff--ppooiinntteerr--iinn--ssttaallee--ssttaacckk--ffrraammee to disable it. This diagnostic warns for paths through the code in which a pointer is dereferenced that points to a variable in a stale stack frame. --WWnnoo--aannaallyyzzeerr--wwrriittee--ttoo--ccoonnsstt This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--wwrriittee--ttoo--ccoonnsstt to disable it. This diagnostic warns for paths through the code in which the ana- lyzer detects an attempt to write through a pointer to a "const" object. However, the analyzer does not prioritize detection of such paths, so false negatives are more likely relative to other warnings. --WWnnoo--aannaallyyzzeerr--wwrriittee--ttoo--ssttrriinngg--lliitteerraall This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--wwrriittee--ttoo--ssttrriinngg--lliitteerraall to disable it. This diagnostic warns for paths through the code in which the ana- lyzer detects an attempt to write through a pointer to a string literal. However, the analyzer does not prioritize detection of such paths, so false negatives are more likely relative to other warnings. --WWnnoo--aannaallyyzzeerr--uussee--ooff--uunniinniittiiaalliizzeedd--vvaalluuee This warning requires --ffaannaallyyzzeerr, which enables it; use --WWnnoo--aannaa-- llyyzzeerr--uussee--ooff--uunniinniittiiaalliizzeedd--vvaalluuee to disable it. This diagnostic warns for paths through the code in which an unini- tialized value is used. Pertinent parameters for controlling the exploration are: ----ppaarraamm aannaa-- llyyzzeerr--bbbb--eexxpplloossiioonn--ffaaccttoorr==_v_a_l_u_e, ----ppaarraamm aannaallyyzzeerr--mmaaxx--eennooddeess--ppeerr--pprroo-- ggrraamm--ppooiinntt==_v_a_l_u_e, ----ppaarraamm aannaallyyzzeerr--mmaaxx--rreeccuurrssiioonn--ddeepptthh==_v_a_l_u_e, and ----ppaarraamm aannaallyyzzeerr--mmiinn--ssnnooddeess--ffoorr--ccaallll--ssuummmmaarryy==_v_a_l_u_e. The following options control the analyzer. --ffaannaallyyzzeerr--ccaallll--ssuummmmaarriieess Simplify interprocedural analysis by computing the effect of cer- tain calls, rather than exploring all paths through the function from callsite to each possible return. If enabled, call summaries are only used for functions with more than one call site, and that are sufficiently complicated (as per ----ppaarraamm aannaallyyzzeerr--mmiinn--ssnnooddeess--ffoorr--ccaallll--ssuummmmaarryy==_v_a_l_u_e). --ffaannaallyyzzeerr--cchheecckkeerr==_n_a_m_e Restrict the analyzer to run just the named checker, and enable it. Some checkers are disabled by default (even with --ffaannaallyyzzeerr), such as the "taint" checker that implements --WWaannaallyyzzeerr--ttaaiinntteedd--aarrrraayy--iinn-- ddeexx, and this option is required to enable them. _N_o_t_e_: currently, --ffaannaallyyzzeerr--cchheecckkeerr==ttaaiinntt disables the following warnings from --ffaannaallyyzzeerr: --WWaannaallyyzzeerr--ddoouubbllee--ffcclloossee --WWaannaallyyzzeerr--ddoouubbllee--ffrreeee --WWaannaallyyzzeerr--eexxppoo-- ssuurree--tthhrroouugghh--oouuttppuutt--ffiillee --WWaannaallyyzzeerr--ffiillee--lleeaakk --WWaannaa-- llyyzzeerr--ffrreeee--ooff--nnoonn--hheeaapp --WWaannaallyyzzeerr--mmaalllloocc--lleeaakk --WWaannaallyyzzeerr--mmiissmmaattcchh-- iinngg--ddeeaallllooccaattiioonn --WWaannaallyyzzeerr--nnuullll--aarrgguummeenntt --WWaannaallyyzzeerr--nnuullll--ddeerreeffeerr-- eennccee --WWaannaallyyzzeerr--ppoossssiibbllee--nnuullll--aarrgguummeenntt --WWaannaallyyzzeerr--ppoossssii-- bbllee--nnuullll--ddeerreeffeerreennccee --WWaannaallyyzzeerr--uunnssaaffee--ccaallll--wwiitthhiinn--ssiiggnnaall--hhaannddlleerr --WWaannaallyyzzeerr--uussee--aafftteerr--ffrreeee --ffnnoo--aannaallyyzzeerr--ffeeaassiibbiilliittyy This option is intended for analyzer developers. By default the analyzer verifies that there is a feasible control flow path for each diagnostic it emits: that the conditions that hold are not mutually exclusive. Diagnostics for which no feasible path can be found are rejected. This filtering can be suppressed with --ffnnoo--aannaallyyzzeerr--ffeeaassiibbiilliittyy, for debugging issues in this code. --ffaannaallyyzzeerr--ffiinnee--ggrraaiinneedd This option is intended for analyzer developers. Internally the analyzer builds an "exploded graph" that combines control flow graphs with data flow information. By default, an edge in this graph can contain the effects of a run of multiple statements within a basic block. With --ffaannaa-- llyyzzeerr--ffiinnee--ggrraaiinneedd, each statement gets its own edge. --ffaannaallyyzzeerr--sshhooww--dduupplliiccaattee--ccoouunntt This option is intended for analyzer developers: if multiple diag- nostics have been detected as being duplicates of each other, it emits a note when reporting the best diagnostic, giving the number of additional diagnostics that were suppressed by the deduplication logic. --ffnnoo--aannaallyyzzeerr--ssttaattee--mmeerrggee This option is intended for analyzer developers. By default the analyzer attempts to simplify analysis by merging sufficiently similar states at each program point as it builds its "exploded graph". With --ffnnoo--aannaallyyzzeerr--ssttaattee--mmeerrggee this merging can be suppressed, for debugging state-handling issues. --ffnnoo--aannaallyyzzeerr--ssttaattee--ppuurrggee This option is intended for analyzer developers. By default the analyzer attempts to simplify analysis by purging aspects of state at a program point that appear to no longer be relevant e.g. the values of locals that aren't accessed later in the function and which aren't relevant to leak analysis. With --ffnnoo--aannaallyyzzeerr--ssttaattee--ppuurrggee this purging of state can be sup- pressed, for debugging state-handling issues. --ffaannaallyyzzeerr--ttrraannssiittiivviittyy This option enables transitivity of constraints within the ana- lyzer. --ffaannaallyyzzeerr--vveerrbboossee--eeddggeess This option is intended for analyzer developers. It enables more verbose, lower-level detail in the descriptions of control flow within diagnostic paths. --ffaannaallyyzzeerr--vveerrbboossee--ssttaattee--cchhaannggeess This option is intended for analyzer developers. It enables more verbose, lower-level detail in the descriptions of events relating to state machines within diagnostic paths. --ffaannaallyyzzeerr--vveerrbboossiittyy==_l_e_v_e_l This option controls the complexity of the control flow paths that are emitted for analyzer diagnostics. The _l_e_v_e_l can be one of: 00 At this level, interprocedural call and return events are dis- played, along with the most pertinent state-change events re- lating to a diagnostic. For example, for a double-"free" diag- nostic, both calls to "free" will be shown. 11 As per the previous level, but also show events for the entry to each function. 22 As per the previous level, but also show events relating to control flow that are significant to triggering the issue (e.g. "true path taken" at a conditional). This level is the default. 33 As per the previous level, but show all control flow events, not just significant ones. 44 This level is intended for analyzer developers; it adds various other events intended for debugging the analyzer. --ffdduummpp--aannaallyyzzeerr Dump internal details about what the analyzer is doing to _f_i_l_e_._a_n_a_- _l_y_z_e_r_._t_x_t. This option is overridden by --ffdduummpp--aannaallyyzzeerr--ssttddeerrrr. --ffdduummpp--aannaallyyzzeerr--ssttddeerrrr Dump internal details about what the analyzer is doing to stderr. This option overrides --ffdduummpp--aannaallyyzzeerr. --ffdduummpp--aannaallyyzzeerr--ccaallllggrraapphh Dump a representation of the call graph suitable for viewing with GraphViz to _f_i_l_e_._c_a_l_l_g_r_a_p_h_._d_o_t. --ffdduummpp--aannaallyyzzeerr--eexxppllooddeedd--ggrraapphh Dump a representation of the "exploded graph" suitable for viewing with GraphViz to _f_i_l_e_._e_g_._d_o_t. Nodes are color-coded based on state-machine states to emphasize state changes. --ffdduummpp--aannaallyyzzeerr--eexxppllooddeedd--nnooddeess Emit diagnostics showing where nodes in the "exploded graph" are in relation to the program source. --ffdduummpp--aannaallyyzzeerr--eexxppllooddeedd--nnooddeess--22 Dump a textual representation of the "exploded graph" to _f_i_l_e_._e_g_._t_x_t. --ffdduummpp--aannaallyyzzeerr--eexxppllooddeedd--nnooddeess--33 Dump a textual representation of the "exploded graph" to one dump file per node, to _f_i_l_e_._e_g_-_i_d_._t_x_t. This is typically a large number of dump files. --ffdduummpp--aannaallyyzzeerr--eexxppllooddeedd--ppaatthhss Dump a textual representation of the "exploded path" for each diag- nostic to _f_i_l_e_._i_d_x_._k_i_n_d_._e_p_a_t_h_._t_x_t. --ffdduummpp--aannaallyyzzeerr--ffeeaassiibbiilliittyy Dump internal details about the analyzer's search for feasible paths. The details are written in a form suitable for viewing with GraphViz to filenames of the form _f_i_l_e_._*_._f_g_._d_o_t, _f_i_l_e_._*_._t_g_._d_o_t, and _f_i_l_e_._*_._f_p_a_t_h_._t_x_t. --ffdduummpp--aannaallyyzzeerr--jjssoonn Dump a compressed JSON representation of analyzer internals to _f_i_l_e_._a_n_a_l_y_z_e_r_._j_s_o_n_._g_z. The precise format is subject to change. --ffdduummpp--aannaallyyzzeerr--ssttaattee--ppuurrggee As per --ffdduummpp--aannaallyyzzeerr--ssuuppeerrggrraapphh, dump a representation of the "supergraph" suitable for viewing with GraphViz, but annotate the graph with information on what state will be purged at each node. The graph is written to _f_i_l_e_._s_t_a_t_e_-_p_u_r_g_e_._d_o_t. --ffdduummpp--aannaallyyzzeerr--ssuuppeerrggrraapphh Dump representations of the "supergraph" suitable for viewing with GraphViz to _f_i_l_e_._s_u_p_e_r_g_r_a_p_h_._d_o_t and to _f_i_l_e_._s_u_p_e_r_g_r_a_p_h_-_e_g_._d_o_t. These show all of the control flow graphs in the program, with in- terprocedural edges for calls and returns. The second dump con- tains annotations showing nodes in the "exploded graph" and diag- nostics associated with them. --ffdduummpp--aannaallyyzzeerr--uunnttrraacckkeedd Emit custom warnings with internal details intended for analyzer developers. OOppttiioonnss ffoorr DDeebbuuggggiinngg YYoouurr PPrrooggrraamm To tell GCC to emit extra information for use by a debugger, in almost all cases you need only to add --gg to your other options. Some debug formats can co-exist (like DWARF with CTF) when each of them is enabled explicitly by adding the respective command line option to your other options. GCC allows you to use --gg with --OO. The shortcuts taken by optimized code may occasionally be surprising: some variables you declared may not exist at all; flow of control may briefly move where you did not expect it; some statements may not be executed because they compute constant results or their values are already at hand; some statements may execute in different places because they have been moved out of loops. Nevertheless it is possible to debug optimized output. This makes it reasonable to use the optimizer for programs that might have bugs. If you are not using some other optimization option, consider using --OOgg with --gg. With no --OO option at all, some compiler passes that collect information useful for debugging do not run at all, so that --OOgg may re- sult in a better debugging experience. --gg Produce debugging information in the operating system's native for- mat (stabs, COFF, XCOFF, or DWARF). GDB can work with this debug- ging information. On most systems that use stabs format, --gg enables use of extra de- bugging information that only GDB can use; this extra information makes debugging work better in GDB but probably makes other debug- gers crash or refuse to read the program. If you want to control for certain whether to generate the extra information, use --ggssttaabbss++, --ggssttaabbss, --ggxxccooffff++, --ggxxccooffff, or --ggvvmmss (see below). --ggggddbb Produce debugging information for use by GDB. This means to use the most expressive format available (DWARF, stabs, or the native format if neither of those are supported), including GDB extensions if at all possible. --ggddwwaarrff --ggddwwaarrff--_v_e_r_s_i_o_n Produce debugging information in DWARF format (if that is sup- ported). The value of _v_e_r_s_i_o_n may be either 2, 3, 4 or 5; the de- fault version for most targets is 5 (with the exception of VxWorks, TPF and Darwin/Mac OS X, which default to version 2, and AIX, which defaults to version 4). Note that with DWARF Version 2, some ports require and always use some non-conflicting DWARF 3 extensions in the unwind tables. Version 4 may require GDB 7.0 and --ffvvaarr--ttrraacckkiinngg--aassssiiggnnmmeennttss for maximum benefit. Version 5 requires GDB 8.0 or higher. GCC no longer supports DWARF Version 1, which is substantially dif- ferent than Version 2 and later. For historical reasons, some other DWARF-related options such as --ffnnoo--ddwwaarrff22--ccffii--aassmm) retain a reference to DWARF Version 2 in their names, but apply to all cur- rently-supported versions of DWARF. --ggbbttff Request BTF debug information. BTF is the default debugging format for the eBPF target. On other targets, like x86, BTF debug infor- mation can be generated along with DWARF debug information when both of the debug formats are enabled explicitly via their respec- tive command line options. --ggccttff --ggccttff_l_e_v_e_l Request CTF debug information and use level to specify how much CTF debug information should be produced. If --ggccttff is specified with- out a value for level, the default level of CTF debug information is 2. CTF debug information can be generated along with DWARF debug in- formation when both of the debug formats are enabled explicitly via their respective command line options. Level 0 produces no CTF debug information at all. Thus, --ggccttff00 negates --ggccttff. Level 1 produces CTF information for tracebacks only. This in- cludes callsite information, but does not include type information. Level 2 produces type information for entities (functions, data ob- jects etc.) at file-scope or global-scope only. --ggssttaabbss Produce debugging information in stabs format (if that is sup- ported), without GDB extensions. This is the format used by DBX on most BSD systems. On MIPS, Alpha and System V Release 4 systems this option produces stabs debugging output that is not understood by DBX. On System V Release 4 systems this option requires the GNU assembler. --ggssttaabbss++ Produce debugging information in stabs format (if that is sup- ported), using GNU extensions understood only by the GNU debugger (GDB). The use of these extensions is likely to make other debug- gers crash or refuse to read the program. --ggxxccooffff Produce debugging information in XCOFF format (if that is sup- ported). This is the format used by the DBX debugger on IBM RS/6000 systems. --ggxxccooffff++ Produce debugging information in XCOFF format (if that is sup- ported), using GNU extensions understood only by the GNU debugger (GDB). The use of these extensions is likely to make other debug- gers crash or refuse to read the program, and may cause assemblers other than the GNU assembler (GAS) to fail with an error. --ggvvmmss Produce debugging information in Alpha/VMS debug format (if that is supported). This is the format used by DEBUG on Alpha/VMS systems. --gg_l_e_v_e_l --ggggddbb_l_e_v_e_l --ggssttaabbss_l_e_v_e_l --ggxxccooffff_l_e_v_e_l --ggvvmmss_l_e_v_e_l Request debugging information and also use _l_e_v_e_l to specify how much information. The default level is 2. Level 0 produces no debug information at all. Thus, --gg00 negates --gg. Level 1 produces minimal information, enough for making backtraces in parts of the program that you don't plan to debug. This in- cludes descriptions of functions and external variables, and line number tables, but no information about local variables. Level 3 includes extra information, such as all the macro defini- tions present in the program. Some debuggers support macro expan- sion when you use --gg33. If you use multiple --gg options, with or without level numbers, the last such option is the one that is effective. --ggddwwaarrff does not accept a concatenated debug level, to avoid confu- sion with --ggddwwaarrff--_l_e_v_e_l. Instead use an additional --gg_l_e_v_e_l option to change the debug level for DWARF. --ffnnoo--eelliimmiinnaattee--uunnuusseedd--ddeebbuugg--ssyymmbboollss By default, no debug information is produced for symbols that are not actually used. Use this option if you want debug information for all symbols. --ffeemmiitt--ccllaassss--ddeebbuugg--aallwwaayyss Instead of emitting debugging information for a C++ class in only one object file, emit it in all object files using the class. This option should be used only with debuggers that are unable to handle the way GCC normally emits debugging information for classes be- cause using this option increases the size of debugging information by as much as a factor of two. --ffnnoo--mmeerrggee--ddeebbuugg--ssttrriinnggss Direct the linker to not merge together strings in the debugging information that are identical in different object files. Merging is not supported by all assemblers or linkers. Merging decreases the size of the debug information in the output file at the cost of increasing link processing time. Merging is enabled by default. --ffddeebbuugg--pprreeffiixx--mmaapp==_o_l_d==_n_e_w When compiling files residing in directory _o_l_d, record debugging information describing them as if the files resided in directory _n_e_w instead. This can be used to replace a build-time path with an install-time path in the debug info. It can also be used to change an absolute path to a relative path by using _. for _n_e_w. This can give more reproducible builds, which are location independent, but may require an extra command to tell GDB where to find the source files. See also --ffffiillee--pprreeffiixx--mmaapp. --ffvvaarr--ttrraacckkiinngg Run variable tracking pass. It computes where variables are stored at each position in code. Better debugging information is then generated (if the debugging information format supports this infor- mation). It is enabled by default when compiling with optimization (--OOss, --OO, --OO22, ...), debugging information (--gg) and the debug info format supports it. --ffvvaarr--ttrraacckkiinngg--aassssiiggnnmmeennttss Annotate assignments to user variables early in the compilation and attempt to carry the annotations over throughout the compilation all the way to the end, in an attempt to improve debug information while optimizing. Use of --ggddwwaarrff--44 is recommended along with it. It can be enabled even if var-tracking is disabled, in which case annotations are created and maintained, but discarded at the end. By default, this flag is enabled together with --ffvvaarr--ttrraacckkiinngg, ex- cept when selective scheduling is enabled. --ggsspplliitt--ddwwaarrff If DWARF debugging information is enabled, separate as much debug- ging information as possible into a separate output file with the extension _._d_w_o. This option allows the build system to avoid link- ing files with debug information. To be useful, this option re- quires a debugger capable of reading _._d_w_o files. --ggddwwaarrff3322 --ggddwwaarrff6644 If DWARF debugging information is enabled, the --ggddwwaarrff3322 selects the 32-bit DWARF format and the --ggddwwaarrff6644 selects the 64-bit DWARF format. The default is target specific, on most targets it is --ggddwwaarrff3322 though. The 32-bit DWARF format is smaller, but can't support more than 2GiB of debug information in any of the DWARF de- bug information sections. The 64-bit DWARF format allows larger debug information and might not be well supported by all consumers yet. --ggddeessccrriibbee--ddiieess Add description attributes to some DWARF DIEs that have no name at- tribute, such as artificial variables, external references and call site parameter DIEs. --ggppuubbnnaammeess Generate DWARF ".debug_pubnames" and ".debug_pubtypes" sections. --ggggnnuu--ppuubbnnaammeess Generate ".debug_pubnames" and ".debug_pubtypes" sections in a for- mat suitable for conversion into a GDB index. This option is only useful with a linker that can produce GDB index version 7. --ffddeebbuugg--ttyyppeess--sseeccttiioonn When using DWARF Version 4 or higher, type DIEs can be put into their own ".debug_types" section instead of making them part of the ".debug_info" section. It is more efficient to put them in a sepa- rate comdat section since the linker can then remove duplicates. But not all DWARF consumers support ".debug_types" sections yet and on some objects ".debug_types" produces larger instead of smaller debugging information. --ggrreeccoorrdd--ggcccc--sswwiittcchheess --ggnnoo--rreeccoorrdd--ggcccc--sswwiittcchheess This switch causes the command-line options used to invoke the com- piler that may affect code generation to be appended to the DW_AT_producer attribute in DWARF debugging information. The op- tions are concatenated with spaces separating them from each other and from the compiler version. It is enabled by default. See also --ffrreeccoorrdd--ggcccc--sswwiittcchheess for another way of storing compiler options into the object file. --ggssttrriicctt--ddwwaarrff Disallow using extensions of later DWARF standard version than se- lected with --ggddwwaarrff--_v_e_r_s_i_o_n. On most targets using non-conflicting DWARF extensions from later standard versions is allowed. --ggnnoo--ssttrriicctt--ddwwaarrff Allow using extensions of later DWARF standard version than se- lected with --ggddwwaarrff--_v_e_r_s_i_o_n. --ggaass--lloocc--ssuuppppoorrtt Inform the compiler that the assembler supports ".loc" directives. It may then use them for the assembler to generate DWARF2+ line number tables. This is generally desirable, because assembler-generated line-num- ber tables are a lot more compact than those the compiler can gen- erate itself. This option will be enabled by default if, at GCC configure time, the assembler was found to support such directives. --ggnnoo--aass--lloocc--ssuuppppoorrtt Force GCC to generate DWARF2+ line number tables internally, if DWARF2+ line number tables are to be generated. --ggaass--llooccvviieeww--ssuuppppoorrtt Inform the compiler that the assembler supports "view" assignment and reset assertion checking in ".loc" directives. This option will be enabled by default if, at GCC configure time, the assembler was found to support them. --ggnnoo--aass--llooccvviieeww--ssuuppppoorrtt Force GCC to assign view numbers internally, if --ggvvaarriiaabbllee--llooccaa-- ttiioonn--vviieewwss are explicitly requested. --ggccoolluummnn--iinnffoo --ggnnoo--ccoolluummnn--iinnffoo Emit location column information into DWARF debugging information, rather than just file and line. This option is enabled by default. --ggssttaatteemmeenntt--ffrroonnttiieerrss --ggnnoo--ssttaatteemmeenntt--ffrroonnttiieerrss This option causes GCC to create markers in the internal represen- tation at the beginning of statements, and to keep them roughly in place throughout compilation, using them to guide the output of "is_stmt" markers in the line number table. This is enabled by de- fault when compiling with optimization (--OOss, --OO11, --OO22, ...), and outputting DWARF 2 debug information at the normal level. --ggvvaarriiaabbllee--llooccaattiioonn--vviieewwss --ggvvaarriiaabbllee--llooccaattiioonn--vviieewwss==iinnccoommppaatt55 --ggnnoo--vvaarriiaabbllee--llooccaattiioonn--vviieewwss Augment variable location lists with progressive view numbers im- plied from the line number table. This enables debug information consumers to inspect state at certain points of the program, even if no instructions associated with the corresponding source loca- tions are present at that point. If the assembler lacks support for view numbers in line number tables, this will cause the com- piler to emit the line number table, which generally makes them somewhat less compact. The augmented line number tables and loca- tion lists are fully backward-compatible, so they can be consumed by debug information consumers that are not aware of these augmen- tations, but they won't derive any benefit from them either. This is enabled by default when outputting DWARF 2 debug informa- tion at the normal level, as long as there is assembler support, --ffvvaarr--ttrraacckkiinngg--aassssiiggnnmmeennttss is enabled and --ggssttrriicctt--ddwwaarrff is not. When assembler support is not available, this may still be enabled, but it will force GCC to output internal line number tables, and if --ggiinntteerrnnaall--rreesseett--llooccaattiioonn--vviieewwss is not enabled, that will most cer- tainly lead to silently mismatching location views. There is a proposed representation for view numbers that is not backward compatible with the location list format introduced in DWARF 5, that can be enabled with --ggvvaarriiaabbllee--llooccaattiioonn--vviieewwss==iinnccoomm-- ppaatt55. This option may be removed in the future, is only provided as a reference implementation of the proposed representation. De- bug information consumers are not expected to support this extended format, and they would be rendered unable to decode location lists using it. --ggiinntteerrnnaall--rreesseett--llooccaattiioonn--vviieewwss --ggnnoo--iinntteerrnnaall--rreesseett--llooccaattiioonn--vviieewwss Attempt to determine location views that can be omitted from loca- tion view lists. This requires the compiler to have very accurate insn length estimates, which isn't always the case, and it may cause incorrect view lists to be generated silently when using an assembler that does not support location view lists. The GNU as- sembler will flag any such error as a "view number mismatch". This is only enabled on ports that define a reliable estimation func- tion. --ggiinnlliinnee--ppooiinnttss --ggnnoo--iinnlliinnee--ppooiinnttss Generate extended debug information for inlined functions. Loca- tion view tracking markers are inserted at inlined entry points, so that address and view numbers can be computed and output in debug information. This can be enabled independently of location views, in which case the view numbers won't be output, but it can only be enabled along with statement frontiers, and it is only enabled by default if location views are enabled. --ggzz[==_t_y_p_e] Produce compressed debug sections in DWARF format, if that is sup- ported. If _t_y_p_e is not given, the default type depends on the ca- pabilities of the assembler and linker used. _t_y_p_e may be one of nnoonnee (don't compress debug sections), zzlliibb (use zlib compression in ELF gABI format), or zzlliibb--ggnnuu (use zlib compression in traditional GNU format). If the linker doesn't support writing compressed de- bug sections, the option is rejected. Otherwise, if the assembler does not support them, --ggzz is silently ignored when producing ob- ject files. --ffeemmiitt--ssttrruucctt--ddeebbuugg--bbaasseeoonnllyy Emit debug information for struct-like types only when the base name of the compilation source file matches the base name of file in which the struct is defined. This option substantially reduces the size of debugging informa- tion, but at significant potential loss in type information to the debugger. See --ffeemmiitt--ssttrruucctt--ddeebbuugg--rreedduucceedd for a less aggressive option. See --ffeemmiitt--ssttrruucctt--ddeebbuugg--ddeettaaiilleedd for more detailed con- trol. This option works only with DWARF debug output. --ffeemmiitt--ssttrruucctt--ddeebbuugg--rreedduucceedd Emit debug information for struct-like types only when the base name of the compilation source file matches the base name of file in which the type is defined, unless the struct is a template or defined in a system header. This option significantly reduces the size of debugging informa- tion, with some potential loss in type information to the debugger. See --ffeemmiitt--ssttrruucctt--ddeebbuugg--bbaasseeoonnllyy for a more aggressive option. See --ffeemmiitt--ssttrruucctt--ddeebbuugg--ddeettaaiilleedd for more detailed control. This option works only with DWARF debug output. --ffeemmiitt--ssttrruucctt--ddeebbuugg--ddeettaaiilleedd[==_s_p_e_c_-_l_i_s_t] Specify the struct-like types for which the compiler generates de- bug information. The intent is to reduce duplicate struct debug information between different object files within the same program. This option is a detailed version of --ffeemmiitt--ssttrruucctt--ddeebbuugg--rreedduucceedd and --ffeemmiitt--ssttrruucctt--ddeebbuugg--bbaasseeoonnllyy, which serves for most needs. A specification has the syn- tax[ddiirr::|iinndd::][oorrdd::|ggeenn::](aannyy|ssyyss|bbaassee|nnoonnee) The optional first word limits the specification to structs that are used directly (ddiirr::) or used indirectly (iinndd::). A struct type is used directly when it is the type of a variable, member. Indi- rect uses arise through pointers to structs. That is, when use of an incomplete struct is valid, the use is indirect. An example is ssttrruucctt oonnee ddiirreecctt;; ssttrruucctt ttwwoo ** iinnddiirreecctt;;. The optional second word limits the specification to ordinary structs (oorrdd::) or generic structs (ggeenn::). Generic structs are a bit complicated to explain. For C++, these are non-explicit spe- cializations of template classes, or non-template classes within the above. Other programming languages have generics, but --ffeemmiitt--ssttrruucctt--ddeebbuugg--ddeettaaiilleedd does not yet implement them. The third word specifies the source files for those structs for which the compiler should emit debug information. The values nnoonnee and aannyy have the normal meaning. The value bbaassee means that the base of name of the file in which the type declaration appears must match the base of the name of the main compilation file. In prac- tice, this means that when compiling _f_o_o_._c, debug information is generated for types declared in that file and _f_o_o_._h, but not other header files. The value ssyyss means those types satisfying bbaassee or declared in system or compiler headers. You may need to experiment to determine the best settings for your application. The default is --ffeemmiitt--ssttrruucctt--ddeebbuugg--ddeettaaiilleedd==aallll. This option works only with DWARF debug output. --ffnnoo--ddwwaarrff22--ccffii--aassmm Emit DWARF unwind info as compiler generated ".eh_frame" section instead of using GAS ".cfi_*" directives. --ffnnoo--eelliimmiinnaattee--uunnuusseedd--ddeebbuugg--ttyyppeess Normally, when producing DWARF output, GCC avoids producing debug symbol output for types that are nowhere used in the source file being compiled. Sometimes it is useful to have GCC emit debugging information for all types declared in a compilation unit, regard- less of whether or not they are actually used in that compilation unit, for example if, in the debugger, you want to cast a value to a type that is not actually used in your program (but is declared). More often, however, this results in a significant amount of wasted space. OOppttiioonnss TThhaatt CCoonnttrrooll OOppttiimmiizzaattiioonn These options control various sorts of optimizations. Without any optimization option, the compiler's goal is to reduce the cost of compilation and to make debugging produce the expected results. Statements are independent: if you stop the program with a breakpoint between statements, you can then assign a new value to any variable or change the program counter to any other statement in the function and get exactly the results you expect from the source code. Turning on optimization flags makes the compiler attempt to improve the performance and/or code size at the expense of compilation time and possibly the ability to debug the program. The compiler performs optimization based on the knowledge it has of the program. Compiling multiple files at once to a single output file mode allows the compiler to use information gained from all of the files when compiling each of them. Not all optimizations are controlled directly by a flag. Only opti- mizations that have a flag are listed in this section. Most optimizations are completely disabled at --OO00 or if an --OO level is not set on the command line, even if individual optimization flags are specified. Similarly, --OOgg suppresses many optimization passes. Depending on the target and how GCC was configured, a slightly differ- ent set of optimizations may be enabled at each --OO level than those listed here. You can invoke GCC with --QQ ----hheellpp==ooppttiimmiizzeerrss to find out the exact set of optimizations that are enabled at each level. --OO --OO11 Optimize. Optimizing compilation takes somewhat more time, and a lot more memory for a large function. With --OO, the compiler tries to reduce code size and execution time, without performing any optimizations that take a great deal of com- pilation time. --OO turns on the following optimization flags: --ffaauuttoo--iinncc--ddeecc --ffbbrraanncchh--ccoouunntt--rreegg --ffccoommbbiinnee--ssttaacckk--aaddjjuussttmmeennttss --ffccoommppaarree--eelliimm --ffccpprroopp--rreeggiisstteerrss --ffddccee --ffddeeffeerr--ppoopp --ffddeellaayyeedd--bbrraanncchh --ffddssee --ffffoorrwwaarrdd--pprrooppaaggaattee --ffgguueessss--bbrraanncchh--pprroobbaabbiilliittyy --ffiiff--ccoonnvveerr-- ssiioonn --ffiiff--ccoonnvveerrssiioonn22 --ffiinnlliinnee--ffuunnccttiioonnss--ccaalllleedd--oonnccee --ffiippaa--mmooddrreeff --ffiippaa--pprrooffiillee --ffiippaa--ppuurree--ccoonnsstt --ffiippaa--rreeffeerreennccee --ffiippaa--rreeffeerreennccee--aadd-- ddrreessssaabbllee --ffmmeerrggee--ccoonnssttaannttss --ffmmoovvee--lloooopp--iinnvvaarriiaannttss --ffmmoovvee--lloooopp--ssttoorreess --ffoommiitt--ffrraammee--ppooiinntteerr --ffrreeoorrddeerr--bblloocckkss --ffsshhrriinnkk--wwrraapp --ffsshhrriinnkk--wwrraapp--sseeppaarraattee --ffsspplliitt--wwiiddee--ttyyppeess --ffssssaa--bbaacckk-- pprroopp --ffssssaa--pphhiioopptt --ffttrreeee--bbiitt--ccccpp --ffttrreeee--ccccpp --ffttrreeee--cchh --ffttrreeee--ccooaa-- lleessccee--vvaarrss --ffttrreeee--ccooppyy--pprroopp --ffttrreeee--ddccee --ffttrreeee--ddoommiinnaattoorr--ooppttss --ffttrreeee--ddssee --ffttrreeee--ffoorrwwpprroopp --ffttrreeee--ffrree --ffttrreeee--pphhiipprroopp --ffttrreeee--ppttaa --ffttrreeee--sscceevv--ccpprroopp --ffttrreeee--ssiinnkk --ffttrreeee--ssllssrr --ffttrreeee--ssrraa --ffttrreeee--tteerr --ffuunniitt--aatt--aa--ttiimmee --OO22 Optimize even more. GCC performs nearly all supported optimiza- tions that do not involve a space-speed tradeoff. As compared to --OO, this option increases both compilation time and the performance of the generated code. --OO22 turns on all optimization flags specified by --OO11. It also turns on the following optimization flags: --ffaalliiggnn--ffuunnccttiioonnss --ffaalliiggnn--jjuummppss --ffaalliiggnn--llaabbeellss --ffaalliiggnn--llooooppss --ffccaalllleerr--ssaavveess --ffccooddee--hhooiissttiinngg --ffccrroossssjjuummppiinngg --ffccssee--ffoollllooww--jjuummppss --ffccssee--sskkiipp--bblloocckkss --ffddeelleettee--nnuullll--ppooiinntteerr--cchheecckkss --ffddeevviirrttuuaalliizzee --ffddeevviirrttuuaalliizzee--ssppeeccuullaattiivveellyy --ffeexxppeennssiivvee--ooppttiimmiizzaattiioonnss --ffffii-- nniittee--llooooppss --ffggccssee --ffggccssee--llmm --ffhhooiisstt--aaddjjaacceenntt--llooaaddss --ffiinnlliinnee--ffuunncc-- ttiioonnss --ffiinnlliinnee--ssmmaallll--ffuunnccttiioonnss --ffiinnddiirreecctt--iinnlliinniinngg --ffiippaa--bbiitt--ccpp --ffiippaa--ccpp --ffiippaa--iiccff --ffiippaa--rraa --ffiippaa--ssrraa --ffiippaa--vvrrpp --ffiissoollaattee--eerrrroo-- nneeoouuss--ppaatthhss--ddeerreeffeerreennccee --ffllrraa--rreemmaatt --ffooppttiimmiizzee--ssiibblliinngg--ccaallllss --ffoopp-- ttiimmiizzee--ssttrrlleenn --ffppaarrttiiaall--iinnlliinniinngg --ffppeeeepphhoollee22 --ffrreeoorrddeerr--bblloocckkss--aallggoo-- rriitthhmm==ssttcc --ffrreeoorrddeerr--bblloocckkss--aanndd--ppaarrttiittiioonn --ffrreeoorrddeerr--ffuunnccttiioonnss --ffrree-- rruunn--ccssee--aafftteerr--lloooopp --ffsscchheedduullee--iinnssnnss --ffsscchheedduullee--iinnssnnss22 --ffsscchheedd--iinn-- tteerrbblloocckk --ffsscchheedd--ssppeecc --ffssttoorree--mmeerrggiinngg --ffssttrriicctt--aalliiaassiinngg --fftthhrreeaadd--jjuummppss --ffttrreeee--bbuuiillttiinn--ccaallll--ddccee --ffttrreeee--lloooopp--vveeccttoorriizzee --ffttrreeee--pprree --ffttrreeee--ssllpp--vveeccttoorriizzee --ffttrreeee--sswwiittcchh--ccoonnvveerrssiioonn --ffttrreeee--ttaaiill--mmeerrggee --ffttrreeee--vvrrpp --ffvveecctt--ccoosstt--mmooddeell==vveerryy--cchheeaapp Please note the warning under --ffggccssee about invoking --OO22 on programs that use computed gotos. --OO33 Optimize yet more. --OO33 turns on all optimizations specified by --OO22 and also turns on the following optimization flags: --ffggccssee--aafftteerr--rreellooaadd --ffiippaa--ccpp--cclloonnee --fflloooopp--iinntteerrcchhaannggee --fflloooopp--uunn-- rroollll--aanndd--jjaamm --ffppeeeell--llooooppss --ffpprreeddiiccttiivvee--ccoommmmoonniinngg --ffsspplliitt--llooooppss --ffss-- pplliitt--ppaatthhss --ffttrreeee--lloooopp--ddiissttrriibbuuttiioonn --ffttrreeee--ppaarrttiiaall--pprree --ffuunnsswwiittcchh--llooooppss --ffvveecctt--ccoosstt--mmooddeell==ddyynnaammiicc --ffvveerr-- ssiioonn--llooooppss--ffoorr--ssttrriiddeess --OO00 Reduce compilation time and make debugging produce the expected re- sults. This is the default. --OOss Optimize for size. --OOss enables all --OO22 optimizations except those that often increase code size: --ffaalliiggnn--ffuunnccttiioonnss --ffaalliiggnn--jjuummppss --ffaalliiggnn--llaabbeellss --ffaalliiggnn--llooooppss --ffpprreeffeettcchh--lloooopp--aarrrraayyss --ffrreeoorrddeerr--bblloocckkss--aallggoorriitthhmm==ssttcc It also enables --ffiinnlliinnee--ffuunnccttiioonnss, causes the compiler to tune for code size rather than execution speed, and performs further opti- mizations designed to reduce code size. --OOffaasstt Disregard strict standards compliance. --OOffaasstt enables all --OO33 op- timizations. It also enables optimizations that are not valid for all standard-compliant programs. It turns on --ffffaasstt--mmaatthh, --ffaall-- llooww--ssttoorree--ddaattaa--rraacceess and the Fortran-specific --ffssttaacckk--aarrrraayyss, un- less --ffmmaaxx--ssttaacckk--vvaarr--ssiizzee is specified, and --ffnnoo--pprrootteecctt--ppaarreennss. It turns off --ffsseemmaannttiicc--iinntteerrppoossiittiioonn. --OOgg Optimize debugging experience. --OOgg should be the optimization level of choice for the standard edit-compile-debug cycle, offering a reasonable level of optimization while maintaining fast compila- tion and a good debugging experience. It is a better choice than --OO00 for producing debuggable code because some compiler passes that collect debug information are disabled at --OO00. Like --OO00, --OOgg completely disables a number of optimization passes so that individual options controlling them have no effect. Other- wise --OOgg enables all --OO11 optimization flags except for those that may interfere with debugging: --ffbbrraanncchh--ccoouunntt--rreegg --ffddeellaayyeedd--bbrraanncchh --ffddssee --ffiiff--ccoonnvveerrssiioonn --ffiiff--ccoonnvveerrssiioonn22 --ffiinnlliinnee--ffuunnccttiioonnss--ccaalllleedd--oonnccee --ffmmoovvee--lloooopp--iinnvvaarrii-- aannttss --ffmmoovvee--lloooopp--ssttoorreess --ffssssaa--pphhiioopptt --ffttrreeee--bbiitt--ccccpp --ffttrreeee--ddssee --ffttrreeee--ppttaa --ffttrreeee--ssrraa --OOzz Optimize aggressively for size rather than speed. This may in- crease the number of instructions executed if those instructions require fewer bytes to encode. --OOzz behaves similarly to --OOss in- cluding enabling most --OO22 optimizations. If you use multiple --OO options, with or without level numbers, the last such option is the one that is effective. Options of the form --ff_f_l_a_g specify machine-independent flags. Most flags have both positive and negative forms; the negative form of --ffffoooo is --ffnnoo--ffoooo. In the table below, only one of the forms is listed---the one you typically use. You can figure out the other form by either re- moving nnoo-- or adding it. The following options control specific optimizations. They are either activated by --OO options or are related to ones that are. You can use the following flags in the rare cases when "fine-tuning" of optimiza- tions to be performed is desired. --ffnnoo--ddeeffeerr--ppoopp For machines that must pop arguments after a function call, always pop the arguments as soon as each function returns. At levels --OO11 and higher, --ffddeeffeerr--ppoopp is the default; this allows the compiler to let arguments accumulate on the stack for several function calls and pop them all at once. --ffffoorrwwaarrdd--pprrooppaaggaattee Perform a forward propagation pass on RTL. The pass tries to com- bine two instructions and checks if the result can be simplified. If loop unrolling is active, two passes are performed and the sec- ond is scheduled after loop unrolling. This option is enabled by default at optimization levels --OO11, --OO22, --OO33, --OOss. --ffffpp--ccoonnttrraacctt==_s_t_y_l_e --ffffpp--ccoonnttrraacctt==ooffff disables floating-point expression contraction. --ffffpp--ccoonnttrraacctt==ffaasstt enables floating-point expression contraction such as forming of fused multiply-add operations if the target has native support for them. --ffffpp--ccoonnttrraacctt==oonn enables floating-point expression contraction if allowed by the language standard. This is currently not implemented and treated equal to --ffffpp--ccoonn-- ttrraacctt==ooffff. The default is --ffffpp--ccoonnttrraacctt==ffaasstt. --ffoommiitt--ffrraammee--ppooiinntteerr Omit the frame pointer in functions that don't need one. This avoids the instructions to save, set up and restore the frame pointer; on many targets it also makes an extra register available. On some targets this flag has no effect because the standard call- ing sequence always uses a frame pointer, so it cannot be omitted. Note that --ffnnoo--oommiitt--ffrraammee--ppooiinntteerr doesn't guarantee the frame pointer is used in all functions. Several targets always omit the frame pointer in leaf functions. Enabled by default at --OO11 and higher. --ffooppttiimmiizzee--ssiibblliinngg--ccaallllss Optimize sibling and tail recursive calls. Enabled at levels --OO22, --OO33, --OOss. --ffooppttiimmiizzee--ssttrrlleenn Optimize various standard C string functions (e.g. "strlen", "strchr" or "strcpy") and their "_FORTIFY_SOURCE" counterparts into faster alternatives. Enabled at levels --OO22, --OO33. --ffnnoo--iinnlliinnee Do not expand any functions inline apart from those marked with the "always_inline" attribute. This is the default when not optimiz- ing. Single functions can be exempted from inlining by marking them with the "noinline" attribute. --ffiinnlliinnee--ssmmaallll--ffuunnccttiioonnss Integrate functions into their callers when their body is smaller than expected function call code (so overall size of program gets smaller). The compiler heuristically decides which functions are simple enough to be worth integrating in this way. This inlining applies to all functions, even those not declared inline. Enabled at levels --OO22, --OO33, --OOss. --ffiinnddiirreecctt--iinnlliinniinngg Inline also indirect calls that are discovered to be known at com- pile time thanks to previous inlining. This option has any effect only when inlining itself is turned on by the --ffiinnlliinnee--ffuunnccttiioonnss or --ffiinnlliinnee--ssmmaallll--ffuunnccttiioonnss options. Enabled at levels --OO22, --OO33, --OOss. --ffiinnlliinnee--ffuunnccttiioonnss Consider all functions for inlining, even if they are not declared inline. The compiler heuristically decides which functions are worth integrating in this way. If all calls to a given function are integrated, and the function is declared "static", then the function is normally not output as assembler code in its own right. Enabled at levels --OO22, --OO33, --OOss. Also enabled by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --ffiinnlliinnee--ffuunnccttiioonnss--ccaalllleedd--oonnccee Consider all "static" functions called once for inlining into their caller even if they are not marked "inline". If a call to a given function is integrated, then the function is not output as assem- bler code in its own right. Enabled at levels --OO11, --OO22, --OO33 and --OOss, but not --OOgg. --ffeeaarrllyy--iinnlliinniinngg Inline functions marked by "always_inline" and functions whose body seems smaller than the function call overhead early before doing --ffpprrooffiillee--ggeenneerraattee instrumentation and real inlining pass. Doing so makes profiling significantly cheaper and usually inlining faster on programs having large chains of nested wrapper functions. Enabled by default. --ffiippaa--ssrraa Perform interprocedural scalar replacement of aggregates, removal of unused parameters and replacement of parameters passed by refer- ence by parameters passed by value. Enabled at levels --OO22, --OO33 and --OOss. --ffiinnlliinnee--lliimmiitt==_n By default, GCC limits the size of functions that can be inlined. This flag allows coarse control of this limit. _n is the size of functions that can be inlined in number of pseudo instructions. Inlining is actually controlled by a number of parameters, which may be specified individually by using ----ppaarraamm _n_a_m_e==_v_a_l_u_e. The --ffiinnlliinnee--lliimmiitt==_n option sets some of these parameters as follows: mmaaxx--iinnlliinnee--iinnssnnss--ssiinnggllee is set to _n/2. mmaaxx--iinnlliinnee--iinnssnnss--aauuttoo is set to _n/2. See below for a documentation of the individual parameters control- ling inlining and for the defaults of these parameters. _N_o_t_e_: there may be no value to --ffiinnlliinnee--lliimmiitt that results in de- fault behavior. _N_o_t_e_: pseudo instruction represents, in this particular context, an abstract measurement of function's size. In no way does it repre- sent a count of assembly instructions and as such its exact meaning might change from one release to an another. --ffnnoo--kkeeeepp--iinnlliinnee--ddlllleexxppoorrtt This is a more fine-grained version of --ffkkeeeepp--iinnlliinnee--ffuunnccttiioonnss, which applies only to functions that are declared using the "dllex- port" attribute or declspec. --ffkkeeeepp--iinnlliinnee--ffuunnccttiioonnss In C, emit "static" functions that are declared "inline" into the object file, even if the function has been inlined into all of its callers. This switch does not affect functions using the "extern inline" extension in GNU C90. In C++, emit any and all inline functions into the object file. --ffkkeeeepp--ssttaattiicc--ffuunnccttiioonnss Emit "static" functions into the object file, even if the function is never used. --ffkkeeeepp--ssttaattiicc--ccoonnssttss Emit variables declared "static const" when optimization isn't turned on, even if the variables aren't referenced. GCC enables this option by default. If you want to force the com- piler to check if a variable is referenced, regardless of whether or not optimization is turned on, use the --ffnnoo--kkeeeepp--ssttaattiicc--ccoonnssttss option. --ffmmeerrggee--ccoonnssttaannttss Attempt to merge identical constants (string constants and float- ing-point constants) across compilation units. This option is the default for optimized compilation if the assem- bler and linker support it. Use --ffnnoo--mmeerrggee--ccoonnssttaannttss to inhibit this behavior. Enabled at levels --OO11, --OO22, --OO33, --OOss. --ffmmeerrggee--aallll--ccoonnssttaannttss Attempt to merge identical constants and identical variables. This option implies --ffmmeerrggee--ccoonnssttaannttss. In addition to --ffmmeerrggee--ccoonn-- ssttaannttss this considers e.g. even constant initialized arrays or ini- tialized constant variables with integral or floating-point types. Languages like C or C++ require each variable, including multiple instances of the same variable in recursive calls, to have distinct locations, so using this option results in non-conforming behavior. --ffmmoodduulloo--sscchheedd Perform swing modulo scheduling immediately before the first sched- uling pass. This pass looks at innermost loops and reorders their instructions by overlapping different iterations. --ffmmoodduulloo--sscchheedd--aallllooww--rreeggmmoovveess Perform more aggressive SMS-based modulo scheduling with register moves allowed. By setting this flag certain anti-dependences edges are deleted, which triggers the generation of reg-moves based on the life-range analysis. This option is effective only with --ffmmoodd-- uulloo--sscchheedd enabled. --ffnnoo--bbrraanncchh--ccoouunntt--rreegg Disable the optimization pass that scans for opportunities to use "decrement and branch" instructions on a count register instead of instruction sequences that decrement a register, compare it against zero, and then branch based upon the result. This option is only meaningful on architectures that support such instructions, which include x86, PowerPC, IA-64 and S/390. Note that the --ffnnoo--bbrraanncchh--ccoouunntt--rreegg option doesn't remove the decrement and branch instructions from the generated instruction stream intro- duced by other optimization passes. The default is --ffbbrraanncchh--ccoouunntt--rreegg at --OO11 and higher, except for --OOgg. --ffnnoo--ffuunnccttiioonn--ccssee Do not put function addresses in registers; make each instruction that calls a constant function contain the function's address ex- plicitly. This option results in less efficient code, but some strange hacks that alter the assembler output may be confused by the optimiza- tions performed when this option is not used. The default is --ffffuunnccttiioonn--ccssee --ffnnoo--zzeerroo--iinniittiiaalliizzeedd--iinn--bbssss If the target supports a BSS section, GCC by default puts variables that are initialized to zero into BSS. This can save space in the resulting code. This option turns off this behavior because some programs explic- itly rely on variables going to the data section---e.g., so that the resulting executable can find the beginning of that section and/or make assumptions based on that. The default is --ffzzeerroo--iinniittiiaalliizzeedd--iinn--bbssss. --fftthhrreeaadd--jjuummppss Perform optimizations that check to see if a jump branches to a lo- cation where another comparison subsumed by the first is found. If so, the first branch is redirected to either the destination of the second branch or a point immediately following it, depending on whether the condition is known to be true or false. Enabled at levels --OO11, --OO22, --OO33, --OOss. --ffsspplliitt--wwiiddee--ttyyppeess When using a type that occupies multiple registers, such as "long long" on a 32-bit system, split the registers apart and allocate them independently. This normally generates better code for those types, but may make debugging more difficult. Enabled at levels --OO11, --OO22, --OO33, --OOss. --ffsspplliitt--wwiiddee--ttyyppeess--eeaarrllyy Fully split wide types early, instead of very late. This option has no effect unless --ffsspplliitt--wwiiddee--ttyyppeess is turned on. This is the default on some targets. --ffccssee--ffoollllooww--jjuummppss In common subexpression elimination (CSE), scan through jump in- structions when the target of the jump is not reached by any other path. For example, when CSE encounters an "if" statement with an "else" clause, CSE follows the jump when the condition tested is false. Enabled at levels --OO22, --OO33, --OOss. --ffccssee--sskkiipp--bblloocckkss This is similar to --ffccssee--ffoollllooww--jjuummppss, but causes CSE to follow jumps that conditionally skip over blocks. When CSE encounters a simple "if" statement with no else clause, --ffccssee--sskkiipp--bblloocckkss causes CSE to follow the jump around the body of the "if". Enabled at levels --OO22, --OO33, --OOss. --ffrreerruunn--ccssee--aafftteerr--lloooopp Re-run common subexpression elimination after loop optimizations are performed. Enabled at levels --OO22, --OO33, --OOss. --ffggccssee Perform a global common subexpression elimination pass. This pass also performs global constant and copy propagation. _N_o_t_e_: When compiling a program using computed gotos, a GCC exten- sion, you may get better run-time performance if you disable the global common subexpression elimination pass by adding --ffnnoo--ggccssee to the command line. Enabled at levels --OO22, --OO33, --OOss. --ffggccssee--llmm When --ffggccssee--llmm is enabled, global common subexpression elimination attempts to move loads that are only killed by stores into them- selves. This allows a loop containing a load/store sequence to be changed to a load outside the loop, and a copy/store within the loop. Enabled by default when --ffggccssee is enabled. --ffggccssee--ssmm When --ffggccssee--ssmm is enabled, a store motion pass is run after global common subexpression elimination. This pass attempts to move stores out of loops. When used in conjunction with --ffggccssee--llmm, loops containing a load/store sequence can be changed to a load be- fore the loop and a store after the loop. Not enabled at any optimization level. --ffggccssee--llaass When --ffggccssee--llaass is enabled, the global common subexpression elimi- nation pass eliminates redundant loads that come after stores to the same memory location (both partial and full redundancies). Not enabled at any optimization level. --ffggccssee--aafftteerr--rreellooaadd When --ffggccssee--aafftteerr--rreellooaadd is enabled, a redundant load elimination pass is performed after reload. The purpose of this pass is to clean up redundant spilling. Enabled by --OO33, --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --ffaaggggrreessssiivvee--lloooopp--ooppttiimmiizzaattiioonnss This option tells the loop optimizer to use language constraints to derive bounds for the number of iterations of a loop. This assumes that loop code does not invoke undefined behavior by for example causing signed integer overflows or out-of-bound array accesses. The bounds for the number of iterations of a loop are used to guide loop unrolling and peeling and loop exit test optimizations. This option is enabled by default. --ffuunnccoonnssttrraaiinneedd--ccoommmmoonnss This option tells the compiler that variables declared in common blocks (e.g. Fortran) may later be overridden with longer trailing arrays. This prevents certain optimizations that depend on knowing the array bounds. --ffccrroossssjjuummppiinngg Perform cross-jumping transformation. This transformation unifies equivalent code and saves code size. The resulting code may or may not perform better than without cross-jumping. Enabled at levels --OO22, --OO33, --OOss. --ffaauuttoo--iinncc--ddeecc Combine increments or decrements of addresses with memory accesses. This pass is always skipped on architectures that do not have in- structions to support this. Enabled by default at --OO11 and higher on architectures that support this. --ffddccee Perform dead code elimination (DCE) on RTL. Enabled by default at --OO11 and higher. --ffddssee Perform dead store elimination (DSE) on RTL. Enabled by default at --OO11 and higher. --ffiiff--ccoonnvveerrssiioonn Attempt to transform conditional jumps into branch-less equiva- lents. This includes use of conditional moves, min, max, set flags and abs instructions, and some tricks doable by standard arith- metics. The use of conditional execution on chips where it is available is controlled by --ffiiff--ccoonnvveerrssiioonn22. Enabled at levels --OO11, --OO22, --OO33, --OOss, but not with --OOgg. --ffiiff--ccoonnvveerrssiioonn22 Use conditional execution (where available) to transform condi- tional jumps into branch-less equivalents. Enabled at levels --OO11, --OO22, --OO33, --OOss, but not with --OOgg. --ffddeecclloonnee--ccttoorr--ddttoorr The C++ ABI requires multiple entry points for constructors and de- structors: one for a base subobject, one for a complete object, and one for a virtual destructor that calls operator delete afterwards. For a hierarchy with virtual bases, the base and complete variants are clones, which means two copies of the function. With this op- tion, the base and complete variants are changed to be thunks that call a common implementation. Enabled by --OOss. --ffddeelleettee--nnuullll--ppooiinntteerr--cchheecckkss Assume that programs cannot safely dereference null pointers, and that no code or data element resides at address zero. This option enables simple constant folding optimizations at all optimization levels. In addition, other optimization passes in GCC use this flag to control global dataflow analyses that eliminate useless checks for null pointers; these assume that a memory access to ad- dress zero always results in a trap, so that if a pointer is checked after it has already been dereferenced, it cannot be null. Note however that in some environments this assumption is not true. Use --ffnnoo--ddeelleettee--nnuullll--ppooiinntteerr--cchheecckkss to disable this optimization for programs that depend on that behavior. This option is enabled by default on most targets. On Nios II ELF, it defaults to off. On AVR, CR16, and MSP430, this option is com- pletely disabled. Passes that use the dataflow information are enabled independently at different optimization levels. --ffddeevviirrttuuaalliizzee Attempt to convert calls to virtual functions to direct calls. This is done both within a procedure and interprocedurally as part of indirect inlining (--ffiinnddiirreecctt--iinnlliinniinngg) and interprocedural con- stant propagation (--ffiippaa--ccpp). Enabled at levels --OO22, --OO33, --OOss. --ffddeevviirrttuuaalliizzee--ssppeeccuullaattiivveellyy Attempt to convert calls to virtual functions to speculative direct calls. Based on the analysis of the type inheritance graph, deter- mine for a given call the set of likely targets. If the set is small, preferably of size 1, change the call into a conditional de- ciding between direct and indirect calls. The speculative calls enable more optimizations, such as inlining. When they seem use- less after further optimization, they are converted back into orig- inal form. --ffddeevviirrttuuaalliizzee--aatt--llttrraannss Stream extra information needed for aggressive devirtualization when running the link-time optimizer in local transformation mode. This option enables more devirtualization but significantly in- creases the size of streamed data. For this reason it is disabled by default. --ffeexxppeennssiivvee--ooppttiimmiizzaattiioonnss Perform a number of minor optimizations that are relatively expen- sive. Enabled at levels --OO22, --OO33, --OOss. --ffrreeee Attempt to remove redundant extension instructions. This is espe- cially helpful for the x86-64 architecture, which implicitly zero- extends in 64-bit registers after writing to their lower 32-bit half. Enabled for Alpha, AArch64 and x86 at levels --OO22, --OO33, --OOss. --ffnnoo--lliiffeettiimmee--ddssee In C++ the value of an object is only affected by changes within its lifetime: when the constructor begins, the object has an inde- terminate value, and any changes during the lifetime of the object are dead when the object is destroyed. Normally dead store elimi- nation will take advantage of this; if your code relies on the value of the object storage persisting beyond the lifetime of the object, you can use this flag to disable this optimization. To preserve stores before the constructor starts (e.g. because your operator new clears the object storage) but still treat the object as dead after the destructor, you can use --fflliiffeettiimmee--ddssee==11. The default behavior can be explicitly selected with --fflliiffeettiimmee--ddssee==22. --fflliiffeettiimmee--ddssee==00 is equivalent to --ffnnoo--lliiffeettiimmee--ddssee. --fflliivvee--rraannggee--sshhrriinnkkaaggee Attempt to decrease register pressure through register live range shrinkage. This is helpful for fast processors with small or mod- erate size register sets. --ffiirraa--aallggoorriitthhmm==_a_l_g_o_r_i_t_h_m Use the specified coloring algorithm for the integrated register allocator. The _a_l_g_o_r_i_t_h_m argument can be pprriioorriittyy, which specifies Chow's priority coloring, or CCBB, which specifies Chaitin-Briggs coloring. Chaitin-Briggs coloring is not implemented for all ar- chitectures, but for those targets that do support it, it is the default because it generates better code. --ffiirraa--rreeggiioonn==_r_e_g_i_o_n Use specified regions for the integrated register allocator. The _r_e_g_i_o_n argument should be one of the following: aallll Use all loops as register allocation regions. This can give the best results for machines with a small and/or irregular register set. mmiixxeedd Use all loops except for loops with small register pressure as the regions. This value usually gives the best results in most cases and for most architectures, and is enabled by default when compiling with optimization for speed (--OO, --OO22, ...). oonnee Use all functions as a single region. This typically results in the smallest code size, and is enabled by default for --OOss or --OO00. --ffiirraa--hhooiisstt--pprreessssuurree Use IRA to evaluate register pressure in the code hoisting pass for decisions to hoist expressions. This option usually results in smaller code, but it can slow the compiler down. This option is enabled at level --OOss for all targets. --ffiirraa--lloooopp--pprreessssuurree Use IRA to evaluate register pressure in loops for decisions to move loop invariants. This option usually results in generation of faster and smaller code on machines with large register files (>= 32 registers), but it can slow the compiler down. This option is enabled at level --OO33 for some targets. --ffnnoo--iirraa--sshhaarree--ssaavvee--sslloottss Disable sharing of stack slots used for saving call-used hard reg- isters living through a call. Each hard register gets a separate stack slot, and as a result function stack frames are larger. --ffnnoo--iirraa--sshhaarree--ssppiillll--sslloottss Disable sharing of stack slots allocated for pseudo-registers. Each pseudo-register that does not get a hard register gets a sepa- rate stack slot, and as a result function stack frames are larger. --ffllrraa--rreemmaatt Enable CFG-sensitive rematerialization in LRA. Instead of loading values of spilled pseudos, LRA tries to rematerialize (recalculate) values if it is profitable. Enabled at levels --OO22, --OO33, --OOss. --ffddeellaayyeedd--bbrraanncchh If supported for the target machine, attempt to reorder instruc- tions to exploit instruction slots available after delayed branch instructions. Enabled at levels --OO11, --OO22, --OO33, --OOss, but not at --OOgg. --ffsscchheedduullee--iinnssnnss If supported for the target machine, attempt to reorder instruc- tions to eliminate execution stalls due to required data being un- available. This helps machines that have slow floating point or memory load instructions by allowing other instructions to be is- sued until the result of the load or floating-point instruction is required. Enabled at levels --OO22, --OO33. --ffsscchheedduullee--iinnssnnss22 Similar to --ffsscchheedduullee--iinnssnnss, but requests an additional pass of in- struction scheduling after register allocation has been done. This is especially useful on machines with a relatively small number of registers and where memory load instructions take more than one cy- cle. Enabled at levels --OO22, --OO33, --OOss. --ffnnoo--sscchheedd--iinntteerrbblloocckk Disable instruction scheduling across basic blocks, which is nor- mally enabled when scheduling before register allocation, i.e. with --ffsscchheedduullee--iinnssnnss or at --OO22 or higher. --ffnnoo--sscchheedd--ssppeecc Disable speculative motion of non-load instructions, which is nor- mally enabled when scheduling before register allocation, i.e. with --ffsscchheedduullee--iinnssnnss or at --OO22 or higher. --ffsscchheedd--pprreessssuurree Enable register pressure sensitive insn scheduling before register allocation. This only makes sense when scheduling before register allocation is enabled, i.e. with --ffsscchheedduullee--iinnssnnss or at --OO22 or higher. Usage of this option can improve the generated code and decrease its size by preventing register pressure increase above the number of available hard registers and subsequent spills in register allocation. --ffsscchheedd--ssppeecc--llooaadd Allow speculative motion of some load instructions. This only makes sense when scheduling before register allocation, i.e. with --ffsscchheedduullee--iinnssnnss or at --OO22 or higher. --ffsscchheedd--ssppeecc--llooaadd--ddaannggeerroouuss Allow speculative motion of more load instructions. This only makes sense when scheduling before register allocation, i.e. with --ffsscchheedduullee--iinnssnnss or at --OO22 or higher. --ffsscchheedd--ssttaalllleedd--iinnssnnss --ffsscchheedd--ssttaalllleedd--iinnssnnss==_n Define how many insns (if any) can be moved prematurely from the queue of stalled insns into the ready list during the second sched- uling pass. --ffnnoo--sscchheedd--ssttaalllleedd--iinnssnnss means that no insns are moved prematurely, --ffsscchheedd--ssttaalllleedd--iinnssnnss==00 means there is no limit on how many queued insns can be moved prematurely. --ffsscchheedd--ssttaalllleedd--iinnssnnss without a value is equivalent to --ffsscchheedd--ssttaalllleedd--iinnssnnss==11. --ffsscchheedd--ssttaalllleedd--iinnssnnss--ddeepp --ffsscchheedd--ssttaalllleedd--iinnssnnss--ddeepp==_n Define how many insn groups (cycles) are examined for a dependency on a stalled insn that is a candidate for premature removal from the queue of stalled insns. This has an effect only during the second scheduling pass, and only if --ffsscchheedd--ssttaalllleedd--iinnssnnss is used. --ffnnoo--sscchheedd--ssttaalllleedd--iinnssnnss--ddeepp is equivalent to --ffsscchheedd--ssttaalllleedd--iinn-- ssnnss--ddeepp==00. --ffsscchheedd--ssttaalllleedd--iinnssnnss--ddeepp without a value is equivalent to --ffsscchheedd--ssttaalllleedd--iinnssnnss--ddeepp==11. --ffsscchheedd22--uussee--ssuuppeerrbblloocckkss When scheduling after register allocation, use superblock schedul- ing. This allows motion across basic block boundaries, resulting in faster schedules. This option is experimental, as not all ma- chine descriptions used by GCC model the CPU closely enough to avoid unreliable results from the algorithm. This only makes sense when scheduling after register allocation, i.e. with --ffsscchheedduullee--iinnssnnss22 or at --OO22 or higher. --ffsscchheedd--ggrroouupp--hheeuurriissttiicc Enable the group heuristic in the scheduler. This heuristic favors the instruction that belongs to a schedule group. This is enabled by default when scheduling is enabled, i.e. with --ffsscchheedduullee--iinnssnnss or --ffsscchheedduullee--iinnssnnss22 or at --OO22 or higher. --ffsscchheedd--ccrriittiiccaall--ppaatthh--hheeuurriissttiicc Enable the critical-path heuristic in the scheduler. This heuris- tic favors instructions on the critical path. This is enabled by default when scheduling is enabled, i.e. with --ffsscchheedduullee--iinnssnnss or --ffsscchheedduullee--iinnssnnss22 or at --OO22 or higher. --ffsscchheedd--ssppeecc--iinnssnn--hheeuurriissttiicc Enable the speculative instruction heuristic in the scheduler. This heuristic favors speculative instructions with greater depen- dency weakness. This is enabled by default when scheduling is en- abled, i.e. with --ffsscchheedduullee--iinnssnnss or --ffsscchheedduullee--iinnssnnss22 or at --OO22 or higher. --ffsscchheedd--rraannkk--hheeuurriissttiicc Enable the rank heuristic in the scheduler. This heuristic favors the instruction belonging to a basic block with greater size or frequency. This is enabled by default when scheduling is enabled, i.e. with --ffsscchheedduullee--iinnssnnss or --ffsscchheedduullee--iinnssnnss22 or at --OO22 or higher. --ffsscchheedd--llaasstt--iinnssnn--hheeuurriissttiicc Enable the last-instruction heuristic in the scheduler. This heuristic favors the instruction that is less dependent on the last instruction scheduled. This is enabled by default when scheduling is enabled, i.e. with --ffsscchheedduullee--iinnssnnss or --ffsscchheedduullee--iinnssnnss22 or at --OO22 or higher. --ffsscchheedd--ddeepp--ccoouunntt--hheeuurriissttiicc Enable the dependent-count heuristic in the scheduler. This heuristic favors the instruction that has more instructions depend- ing on it. This is enabled by default when scheduling is enabled, i.e. with --ffsscchheedduullee--iinnssnnss or --ffsscchheedduullee--iinnssnnss22 or at --OO22 or higher. --ffrreesscchheedduullee--mmoodduulloo--sscchheedduulleedd--llooooppss Modulo scheduling is performed before traditional scheduling. If a loop is modulo scheduled, later scheduling passes may change its schedule. Use this option to control that behavior. --ffsseelleeccttiivvee--sscchheedduulliinngg Schedule instructions using selective scheduling algorithm. Selec- tive scheduling runs instead of the first scheduler pass. --ffsseelleeccttiivvee--sscchheedduulliinngg22 Schedule instructions using selective scheduling algorithm. Selec- tive scheduling runs instead of the second scheduler pass. --ffsseell--sscchheedd--ppiippeelliinniinngg Enable software pipelining of innermost loops during selective scheduling. This option has no effect unless one of --ffsseelleecc-- ttiivvee--sscchheedduulliinngg or --ffsseelleeccttiivvee--sscchheedduulliinngg22 is turned on. --ffsseell--sscchheedd--ppiippeelliinniinngg--oouutteerr--llooooppss When pipelining loops during selective scheduling, also pipeline outer loops. This option has no effect unless --ffsseell--sscchheedd--ppiippeelliinn-- iinngg is turned on. --ffsseemmaannttiicc--iinntteerrppoossiittiioonn Some object formats, like ELF, allow interposing of symbols by the dynamic linker. This means that for symbols exported from the DSO, the compiler cannot perform interprocedural propagation, inlining and other optimizations in anticipation that the function or vari- able in question may change. While this feature is useful, for ex- ample, to rewrite memory allocation functions by a debugging imple- mentation, it is expensive in the terms of code quality. With --ffnnoo--sseemmaannttiicc--iinntteerrppoossiittiioonn the compiler assumes that if interposi- tion happens for functions the overwriting function will have pre- cisely the same semantics (and side effects). Similarly if inter- position happens for variables, the constructor of the variable will be the same. The flag has no effect for functions explicitly declared inline (where it is never allowed for interposition to change semantics) and for symbols explicitly declared weak. --ffsshhrriinnkk--wwrraapp Emit function prologues only before parts of the function that need it, rather than at the top of the function. This flag is enabled by default at --OO and higher. --ffsshhrriinnkk--wwrraapp--sseeppaarraattee Shrink-wrap separate parts of the prologue and epilogue separately, so that those parts are only executed when needed. This option is on by default, but has no effect unless --ffsshhrriinnkk--wwrraapp is also turned on and the target supports this. --ffccaalllleerr--ssaavveess Enable allocation of values to registers that are clobbered by function calls, by emitting extra instructions to save and restore the registers around such calls. Such allocation is done only when it seems to result in better code. This option is always enabled by default on certain machines, usu- ally those which have no call-preserved registers to use instead. Enabled at levels --OO22, --OO33, --OOss. --ffccoommbbiinnee--ssttaacckk--aaddjjuussttmmeennttss Tracks stack adjustments (pushes and pops) and stack memory refer- ences and then tries to find ways to combine them. Enabled by default at --OO11 and higher. --ffiippaa--rraa Use caller save registers for allocation if those registers are not used by any called function. In that case it is not necessary to save and restore them around calls. This is only possible if called functions are part of same compilation unit as current func- tion and they are compiled before it. Enabled at levels --OO22, --OO33, --OOss, however the option is disabled if generated code will be instrumented for profiling (--pp, or --ppgg) or if callee's register usage cannot be known exactly (this happens on targets that do not expose prologues and epilogues in RTL). --ffccoonnsseerrvvee--ssttaacckk Attempt to minimize stack usage. The compiler attempts to use less stack space, even if that makes the program slower. This option implies setting the llaarrggee--ssttaacckk--ffrraammee parameter to 100 and the llaarrggee--ssttaacckk--ffrraammee--ggrroowwtthh parameter to 400. --ffttrreeee--rreeaassssoocc Perform reassociation on trees. This flag is enabled by default at --OO11 and higher. --ffccooddee--hhooiissttiinngg Perform code hoisting. Code hoisting tries to move the evaluation of expressions executed on all paths to the function exit as early as possible. This is especially useful as a code size optimiza- tion, but it often helps for code speed as well. This flag is en- abled by default at --OO22 and higher. --ffttrreeee--pprree Perform partial redundancy elimination (PRE) on trees. This flag is enabled by default at --OO22 and --OO33. --ffttrreeee--ppaarrttiiaall--pprree Make partial redundancy elimination (PRE) more aggressive. This flag is enabled by default at --OO33. --ffttrreeee--ffoorrwwpprroopp Perform forward propagation on trees. This flag is enabled by de- fault at --OO11 and higher. --ffttrreeee--ffrree Perform full redundancy elimination (FRE) on trees. The difference between FRE and PRE is that FRE only considers expressions that are computed on all paths leading to the redundant computation. This analysis is faster than PRE, though it exposes fewer redundancies. This flag is enabled by default at --OO11 and higher. --ffttrreeee--pphhiipprroopp Perform hoisting of loads from conditional pointers on trees. This pass is enabled by default at --OO11 and higher. --ffhhooiisstt--aaddjjaacceenntt--llooaaddss Speculatively hoist loads from both branches of an if-then-else if the loads are from adjacent locations in the same structure and the target architecture has a conditional move instruction. This flag is enabled by default at --OO22 and higher. --ffttrreeee--ccooppyy--pprroopp Perform copy propagation on trees. This pass eliminates unneces- sary copy operations. This flag is enabled by default at --OO11 and higher. --ffiippaa--ppuurree--ccoonnsstt Discover which functions are pure or constant. Enabled by default at --OO11 and higher. --ffiippaa--rreeffeerreennccee Discover which static variables do not escape the compilation unit. Enabled by default at --OO11 and higher. --ffiippaa--rreeffeerreennccee--aaddddrreessssaabbllee Discover read-only, write-only and non-addressable static vari- ables. Enabled by default at --OO11 and higher. --ffiippaa--ssttaacckk--aalliiggnnmmeenntt Reduce stack alignment on call sites if possible. Enabled by de- fault. --ffiippaa--ppttaa Perform interprocedural pointer analysis and interprocedural modi- fication and reference analysis. This option can cause excessive memory and compile-time usage on large compilation units. It is not enabled by default at any optimization level. --ffiippaa--pprrooffiillee Perform interprocedural profile propagation. The functions called only from cold functions are marked as cold. Also functions exe- cuted once (such as "cold", "noreturn", static constructors or de- structors) are identified. Cold functions and loop less parts of functions executed once are then optimized for size. Enabled by default at --OO11 and higher. --ffiippaa--mmooddrreeff Perform interprocedural mod/ref analysis. This optimization ana- lyzes the side effects of functions (memory locations that are mod- ified or referenced) and enables better optimization across the function call boundary. This flag is enabled by default at --OO11 and higher. --ffiippaa--ccpp Perform interprocedural constant propagation. This optimization analyzes the program to determine when values passed to functions are constants and then optimizes accordingly. This optimization can substantially increase performance if the application has con- stants passed to functions. This flag is enabled by default at --OO22, --OOss and --OO33. It is also enabled by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --ffiippaa--ccpp--cclloonnee Perform function cloning to make interprocedural constant propaga- tion stronger. When enabled, interprocedural constant propagation performs function cloning when externally visible function can be called with constant arguments. Because this optimization can cre- ate multiple copies of functions, it may significantly increase code size (see ----ppaarraamm iippaa--ccpp--uunniitt--ggrroowwtthh==_v_a_l_u_e). This flag is en- abled by default at --OO33. It is also enabled by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --ffiippaa--bbiitt--ccpp When enabled, perform interprocedural bitwise constant propagation. This flag is enabled by default at --OO22 and by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. It requires that --ffiippaa--ccpp is enabled. --ffiippaa--vvrrpp When enabled, perform interprocedural propagation of value ranges. This flag is enabled by default at --OO22. It requires that --ffiippaa--ccpp is enabled. --ffiippaa--iiccff Perform Identical Code Folding for functions and read-only vari- ables. The optimization reduces code size and may disturb unwind stacks by replacing a function by equivalent one with a different name. The optimization works more effectively with link-time opti- mization enabled. Although the behavior is similar to the Gold Linker's ICF optimiza- tion, GCC ICF works on different levels and thus the optimizations are not same - there are equivalences that are found only by GCC and equivalences found only by Gold. This flag is enabled by default at --OO22 and --OOss. --fflliivvee--ppaattcchhiinngg==_l_e_v_e_l Control GCC's optimizations to produce output suitable for live-patching. If the compiler's optimization uses a function's body or informa- tion extracted from its body to optimize/change another function, the latter is called an impacted function of the former. If a function is patched, its impacted functions should be patched too. The impacted functions are determined by the compiler's interproce- dural optimizations. For example, a caller is impacted when inlin- ing a function into its caller, cloning a function and changing its caller to call this new clone, or extracting a function's pure- ness/constness information to optimize its direct or indirect call- ers, etc. Usually, the more IPA optimizations enabled, the larger the number of impacted functions for each function. In order to control the number of impacted functions and more easily compute the list of impacted function, IPA optimizations can be partially enabled at two different levels. The _l_e_v_e_l argument should be one of the following: iinnlliinnee--cclloonnee Only enable inlining and cloning optimizations, which includes inlining, cloning, interprocedural scalar replacement of aggre- gates and partial inlining. As a result, when patching a func- tion, all its callers and its clones' callers are impacted, therefore need to be patched as well. --fflliivvee--ppaattcchhiinngg==iinnlliinnee--cclloonnee disables the following optimiza- tion flags: --ffwwhhoollee--pprrooggrraamm --ffiippaa--ppttaa --ffiippaa--rreeffeerreennccee --ffiippaa--rraa --ffiippaa--iiccff --ffiippaa--iiccff--ffuunnccttiioonnss --ffiippaa--iiccff--vvaarriiaabblleess --ffiippaa--bbiitt--ccpp --ffiippaa--vvrrpp --ffiippaa--ppuurree--ccoonnsstt --ffiippaa--rreeffeerreennccee--aadd-- ddrreessssaabbllee --ffiippaa--ssttaacckk--aalliiggnnmmeenntt --ffiippaa--mmooddrreeff iinnlliinnee--oonnllyy--ssttaattiicc Only enable inlining of static functions. As a result, when patching a static function, all its callers are impacted and so need to be patched as well. In addition to all the flags that --fflliivvee--ppaattcchhiinngg==iinnlliinnee--cclloonnee disables, --fflliivvee--ppaattcchhiinngg==iinnlliinnee--oonnllyy--ssttaattiicc disables the fol- lowing additional optimization flags: --ffiippaa--ccpp--cclloonnee --ffiippaa--ssrraa --ffppaarrttiiaall--iinnlliinniinngg --ffiippaa--ccpp When --fflliivvee--ppaattcchhiinngg is specified without any value, the default value is _i_n_l_i_n_e_-_c_l_o_n_e. This flag is disabled by default. Note that --fflliivvee--ppaattcchhiinngg is not supported with link-time optimiza- tion (--ffllttoo). --ffiissoollaattee--eerrrroonneeoouuss--ppaatthhss--ddeerreeffeerreennccee Detect paths that trigger erroneous or undefined behavior due to dereferencing a null pointer. Isolate those paths from the main control flow and turn the statement with erroneous or undefined be- havior into a trap. This flag is enabled by default at --OO22 and higher and depends on --ffddeelleettee--nnuullll--ppooiinntteerr--cchheecckkss also being en- abled. --ffiissoollaattee--eerrrroonneeoouuss--ppaatthhss--aattttrriibbuuttee Detect paths that trigger erroneous or undefined behavior due to a null value being used in a way forbidden by a "returns_nonnull" or "nonnull" attribute. Isolate those paths from the main control flow and turn the statement with erroneous or undefined behavior into a trap. This is not currently enabled, but may be enabled by --OO22 in the future. --ffttrreeee--ssiinnkk Perform forward store motion on trees. This flag is enabled by de- fault at --OO11 and higher. --ffttrreeee--bbiitt--ccccpp Perform sparse conditional bit constant propagation on trees and propagate pointer alignment information. This pass only operates on local scalar variables and is enabled by default at --OO11 and higher, except for --OOgg. It requires that --ffttrreeee--ccccpp is enabled. --ffttrreeee--ccccpp Perform sparse conditional constant propagation (CCP) on trees. This pass only operates on local scalar variables and is enabled by default at --OO11 and higher. --ffssssaa--bbaacckkpprroopp Propagate information about uses of a value up the definition chain in order to simplify the definitions. For example, this pass strips sign operations if the sign of a value never matters. The flag is enabled by default at --OO11 and higher. --ffssssaa--pphhiioopptt Perform pattern matching on SSA PHI nodes to optimize conditional code. This pass is enabled by default at --OO11 and higher, except for --OOgg. --ffttrreeee--sswwiittcchh--ccoonnvveerrssiioonn Perform conversion of simple initializations in a switch to ini- tializations from a scalar array. This flag is enabled by default at --OO22 and higher. --ffttrreeee--ttaaiill--mmeerrggee Look for identical code sequences. When found, replace one with a jump to the other. This optimization is known as tail merging or cross jumping. This flag is enabled by default at --OO22 and higher. The compilation time in this pass can be limited using mmaaxx--ttaaiill-- mmeerrggee--ccoommppaarriissoonnss parameter and mmaaxx--ttaaiill--mmeerrggee--iitteerraattiioonnss parame- ter. --ffttrreeee--ddccee Perform dead code elimination (DCE) on trees. This flag is enabled by default at --OO11 and higher. --ffttrreeee--bbuuiillttiinn--ccaallll--ddccee Perform conditional dead code elimination (DCE) for calls to built- in functions that may set "errno" but are otherwise free of side effects. This flag is enabled by default at --OO22 and higher if --OOss is not also specified. --ffffiinniittee--llooooppss Assume that a loop with an exit will eventually take the exit and not loop indefinitely. This allows the compiler to remove loops that otherwise have no side-effects, not considering eventual end- less looping as such. This option is enabled by default at --OO22 for C++ with -std=c++11 or higher. --ffttrreeee--ddoommiinnaattoorr--ooppttss Perform a variety of simple scalar cleanups (constant/copy propaga- tion, redundancy elimination, range propagation and expression sim- plification) based on a dominator tree traversal. This also per- forms jump threading (to reduce jumps to jumps). This flag is en- abled by default at --OO11 and higher. --ffttrreeee--ddssee Perform dead store elimination (DSE) on trees. A dead store is a store into a memory location that is later overwritten by another store without any intervening loads. In this case the earlier store can be deleted. This flag is enabled by default at --OO11 and higher. --ffttrreeee--cchh Perform loop header copying on trees. This is beneficial since it increases effectiveness of code motion optimizations. It also saves one jump. This flag is enabled by default at --OO11 and higher. It is not enabled for --OOss, since it usually increases code size. --ffttrreeee--lloooopp--ooppttiimmiizzee Perform loop optimizations on trees. This flag is enabled by de- fault at --OO11 and higher. --ffttrreeee--lloooopp--lliinneeaarr --fflloooopp--ssttrriipp--mmiinnee --fflloooopp--bblloocckk Perform loop nest optimizations. Same as --fflloooopp--nneesstt--ooppttiimmiizzee. To use this code transformation, GCC has to be configured with ----wwiitthh--iissll to enable the Graphite loop transformation infrastruc- ture. --ffggrraapphhiittee--iiddeennttiittyy Enable the identity transformation for graphite. For every SCoP we generate the polyhedral representation and transform it back to gimple. Using --ffggrraapphhiittee--iiddeennttiittyy we can check the costs or bene- fits of the GIMPLE -> GRAPHITE -> GIMPLE transformation. Some min- imal optimizations are also performed by the code generator isl, like index splitting and dead code elimination in loops. --fflloooopp--nneesstt--ooppttiimmiizzee Enable the isl based loop nest optimizer. This is a generic loop nest optimizer based on the Pluto optimization algorithms. It cal- culates a loop structure optimized for data-locality and parallel- ism. This option is experimental. --fflloooopp--ppaarraalllleelliizzee--aallll Use the Graphite data dependence analysis to identify loops that can be parallelized. Parallelize all the loops that can be ana- lyzed to not contain loop carried dependences without checking that it is profitable to parallelize the loops. --ffttrreeee--ccooaalleessccee--vvaarrss While transforming the program out of the SSA representation, at- tempt to reduce copying by coalescing versions of different user- defined variables, instead of just compiler temporaries. This may severely limit the ability to debug an optimized program compiled with --ffnnoo--vvaarr--ttrraacckkiinngg--aassssiiggnnmmeennttss. In the negated form, this flag prevents SSA coalescing of user variables. This option is enabled by default if optimization is enabled, and it does very little oth- erwise. --ffttrreeee--lloooopp--iiff--ccoonnvveerrtt Attempt to transform conditional jumps in the innermost loops to branch-less equivalents. The intent is to remove control-flow from the innermost loops in order to improve the ability of the vector- ization pass to handle these loops. This is enabled by default if vectorization is enabled. --ffttrreeee--lloooopp--ddiissttrriibbuuttiioonn Perform loop distribution. This flag can improve cache performance on big loop bodies and allow further loop optimizations, like par- allelization or vectorization, to take place. For example, the loop DO I = 1, N A(I) = B(I) + C D(I) = E(I) * F ENDDO is transformed to DO I = 1, N A(I) = B(I) + C ENDDO DO I = 1, N D(I) = E(I) * F ENDDO This flag is enabled by default at --OO33. It is also enabled by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --ffttrreeee--lloooopp--ddiissttrriibbuuttee--ppaatttteerrnnss Perform loop distribution of patterns that can be code generated with calls to a library. This flag is enabled by default at --OO22 and higher, and by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. This pass distributes the initialization loops and generates a call to memset zero. For example, the loop DO I = 1, N A(I) = 0 B(I) = A(I) + I ENDDO is transformed to DO I = 1, N A(I) = 0 ENDDO DO I = 1, N B(I) = A(I) + I ENDDO and the initialization loop is transformed into a call to memset zero. This flag is enabled by default at --OO33. It is also enabled by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --fflloooopp--iinntteerrcchhaannggee Perform loop interchange outside of graphite. This flag can im- prove cache performance on loop nest and allow further loop opti- mizations, like vectorization, to take place. For example, the loop for (int i = 0; i < N; i++) for (int j = 0; j < N; j++) for (int k = 0; k < N; k++) c[i][j] = c[i][j] + a[i][k]*b[k][j]; is transformed to for (int i = 0; i < N; i++) for (int k = 0; k < N; k++) for (int j = 0; j < N; j++) c[i][j] = c[i][j] + a[i][k]*b[k][j]; This flag is enabled by default at --OO33. It is also enabled by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --fflloooopp--uunnrroollll--aanndd--jjaamm Apply unroll and jam transformations on feasible loops. In a loop nest this unrolls the outer loop by some factor and fuses the re- sulting multiple inner loops. This flag is enabled by default at --OO33. It is also enabled by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --ffttrreeee--lloooopp--iimm Perform loop invariant motion on trees. This pass moves only in- variants that are hard to handle at RTL level (function calls, op- erations that expand to nontrivial sequences of insns). With --ffuunnsswwiittcchh--llooooppss it also moves operands of conditions that are in- variant out of the loop, so that we can use just trivial invariant- ness analysis in loop unswitching. The pass also includes store motion. --ffttrreeee--lloooopp--iivvccaannoonn Create a canonical counter for number of iterations in loops for which determining number of iterations requires complicated analy- sis. Later optimizations then may determine the number easily. Useful especially in connection with unrolling. --ffttrreeee--sscceevv--ccpprroopp Perform final value replacement. If a variable is modified in a loop in such a way that its value when exiting the loop can be de- termined using only its initial value and the number of loop itera- tions, replace uses of the final value by such a computation, pro- vided it is sufficiently cheap. This reduces data dependencies and may allow further simplifications. Enabled by default at --OO11 and higher. --ffiivvooppttss Perform induction variable optimizations (strength reduction, in- duction variable merging and induction variable elimination) on trees. --ffttrreeee--ppaarraalllleelliizzee--llooooppss==nn Parallelize loops, i.e., split their iteration space to run in n threads. This is only possible for loops whose iterations are in- dependent and can be arbitrarily reordered. The optimization is only profitable on multiprocessor machines, for loops that are CPU-intensive, rather than constrained e.g. by memory bandwidth. This option implies --pptthhrreeaadd, and thus is only supported on targets that have support for --pptthhrreeaadd. --ffttrreeee--ppttaa Perform function-local points-to analysis on trees. This flag is enabled by default at --OO11 and higher, except for --OOgg. --ffttrreeee--ssrraa Perform scalar replacement of aggregates. This pass replaces structure references with scalars to prevent committing structures to memory too early. This flag is enabled by default at --OO11 and higher, except for --OOgg. --ffssttoorree--mmeerrggiinngg Perform merging of narrow stores to consecutive memory addresses. This pass merges contiguous stores of immediate values narrower than a word into fewer wider stores to reduce the number of in- structions. This is enabled by default at --OO22 and higher as well as --OOss. --ffttrreeee--tteerr Perform temporary expression replacement during the SSA->normal phase. Single use/single def temporaries are replaced at their use location with their defining expression. This results in non-GIM- PLE code, but gives the expanders much more complex trees to work on resulting in better RTL generation. This is enabled by default at --OO11 and higher. --ffttrreeee--ssllssrr Perform straight-line strength reduction on trees. This recognizes related expressions involving multiplications and replaces them by less expensive calculations when possible. This is enabled by de- fault at --OO11 and higher. --ffttrreeee--vveeccttoorriizzee Perform vectorization on trees. This flag enables --ffttrreeee--lloooopp--vveecc-- ttoorriizzee and --ffttrreeee--ssllpp--vveeccttoorriizzee if not explicitly specified. --ffttrreeee--lloooopp--vveeccttoorriizzee Perform loop vectorization on trees. This flag is enabled by de- fault at --OO22 and by --ffttrreeee--vveeccttoorriizzee, --ffpprrooffiillee--uussee, and --ffaauuttoo--pprrooffiillee. --ffttrreeee--ssllpp--vveeccttoorriizzee Perform basic block vectorization on trees. This flag is enabled by default at --OO22 and by --ffttrreeee--vveeccttoorriizzee, --ffpprrooffiillee--uussee, and --ffaauuttoo--pprrooffiillee. --ffttrriivviiaall--aauuttoo--vvaarr--iinniitt==_c_h_o_i_c_e Initialize automatic variables with either a pattern or with zeroes to increase the security and predictability of a program by pre- venting uninitialized memory disclosure and use. GCC still consid- ers an automatic variable that doesn't have an explicit initializer as uninitialized, --WWuunniinniittiiaalliizzeedd and --WWaannaallyyzzeerr--uussee--ooff--uunniinniittiiaall-- iizzeedd--vvaalluuee will still report warning messages on such automatic variables. With this option, GCC will also initialize any padding of automatic variables that have structure or union types to ze- roes. However, the current implementation cannot initialize auto- matic variables that are declared between the controlling expres- sion and the first case of a "switch" statement. Using --WWttrriivv-- iiaall--aauuttoo--vvaarr--iinniitt to report all such cases. The three values of _c_h_o_i_c_e are: * uunniinniittiiaalliizzeedd doesn't initialize any automatic variables. This is C and C++'s default. * ppaatttteerrnn Initialize automatic variables with values which will likely transform logic bugs into crashes down the line, are easily recognized in a crash dump and without being values that programmers can rely on for useful program semantics. The cur- rent value is byte-repeatable pattern with byte "0xFE". The values used for pattern initialization might be changed in the future. * zzeerroo Initialize automatic variables with zeroes. The default is uunniinniittiiaalliizzeedd. You can control this behavior for a specific variable by using the variable attribute "uninitialized". --ffvveecctt--ccoosstt--mmooddeell==_m_o_d_e_l Alter the cost model used for vectorization. The _m_o_d_e_l argument should be one of uunnlliimmiitteedd, ddyynnaammiicc, cchheeaapp or vveerryy--cchheeaapp. With the uunnlliimmiitteedd model the vectorized code-path is assumed to be prof- itable while with the ddyynnaammiicc model a runtime check guards the vec- torized code-path to enable it only for iteration counts that will likely execute faster than when executing the original scalar loop. The cchheeaapp model disables vectorization of loops where doing so would be cost prohibitive for example due to required runtime checks for data dependence or alignment but otherwise is equal to the ddyynnaammiicc model. The vveerryy--cchheeaapp model only allows vectorization if the vector code would entirely replace the scalar code that is being vectorized. For example, if each iteration of a vectorized loop would only be able to handle exactly four iterations of the scalar loop, the vveerryy--cchheeaapp model would only allow vectorization if the scalar iteration count is known to be a multiple of four. The default cost model depends on other optimization flags and is either ddyynnaammiicc or cchheeaapp. --ffssiimmdd--ccoosstt--mmooddeell==_m_o_d_e_l Alter the cost model used for vectorization of loops marked with the OpenMP simd directive. The _m_o_d_e_l argument should be one of uunn-- lliimmiitteedd, ddyynnaammiicc, cchheeaapp. All values of _m_o_d_e_l have the same meaning as described in --ffvveecctt--ccoosstt--mmooddeell and by default a cost model de- fined with --ffvveecctt--ccoosstt--mmooddeell is used. --ffttrreeee--vvrrpp Perform Value Range Propagation on trees. This is similar to the constant propagation pass, but instead of values, ranges of values are propagated. This allows the optimizers to remove unnecessary range checks like array bound checks and null pointer checks. This is enabled by default at --OO22 and higher. Null pointer check elimi- nation is only done if --ffddeelleettee--nnuullll--ppooiinntteerr--cchheecckkss is enabled. --ffsspplliitt--ppaatthhss Split paths leading to loop backedges. This can improve dead code elimination and common subexpression elimination. This is enabled by default at --OO33 and above. --ffsspplliitt--iivvss--iinn--uunnrroolllleerr Enables expression of values of induction variables in later itera- tions of the unrolled loop using the value in the first iteration. This breaks long dependency chains, thus improving efficiency of the scheduling passes. A combination of --ffwweebb and CSE is often sufficient to obtain the same effect. However, that is not reliable in cases where the loop body is more complicated than a single basic block. It also does not work at all on some architectures due to restrictions in the CSE pass. This optimization is enabled by default. --ffvvaarriiaabbllee--eexxppaannssiioonn--iinn--uunnrroolllleerr With this option, the compiler creates multiple copies of some lo- cal variables when unrolling a loop, which can result in superior code. This optimization is enabled by default for PowerPC targets, but disabled by default otherwise. --ffppaarrttiiaall--iinnlliinniinngg Inline parts of functions. This option has any effect only when inlining itself is turned on by the --ffiinnlliinnee--ffuunnccttiioonnss or --ffiinn-- lliinnee--ssmmaallll--ffuunnccttiioonnss options. Enabled at levels --OO22, --OO33, --OOss. --ffpprreeddiiccttiivvee--ccoommmmoonniinngg Perform predictive commoning optimization, i.e., reusing computa- tions (especially memory loads and stores) performed in previous iterations of loops. This option is enabled at level --OO33. It is also enabled by --ffpprroo-- ffiillee--uussee and --ffaauuttoo--pprrooffiillee. --ffpprreeffeettcchh--lloooopp--aarrrraayyss If supported by the target machine, generate instructions to prefetch memory to improve the performance of loops that access large arrays. This option may generate better or worse code; results are highly dependent on the structure of loops within the source code. Disabled at level --OOss. --ffnnoo--pprriinnttff--rreettuurrnn--vvaalluuee Do not substitute constants for known return value of formatted output functions such as "sprintf", "snprintf", "vsprintf", and "vsnprintf" (but not "printf" of "fprintf"). This transformation allows GCC to optimize or even eliminate branches based on the known return value of these functions called with arguments that are either constant, or whose values are known to be in a range that makes determining the exact return value possible. For exam- ple, when --ffpprriinnttff--rreettuurrnn--vvaalluuee is in effect, both the branch and the body of the "if" statement (but not the call to "snprint") can be optimized away when "i" is a 32-bit or smaller integer because the return value is guaranteed to be at most 8. char buf[9]; if (snprintf (buf, "%08x", i) >= sizeof buf) ... The --ffpprriinnttff--rreettuurrnn--vvaalluuee option relies on other optimizations and yields best results with --OO22 and above. It works in tandem with the --WWffoorrmmaatt--oovveerrffllooww and --WWffoorrmmaatt--ttrruunnccaattiioonn options. The --ffpprriinnttff--rreettuurrnn--vvaalluuee option is enabled by default. --ffnnoo--ppeeeepphhoollee --ffnnoo--ppeeeepphhoollee22 Disable any machine-specific peephole optimizations. The differ- ence between --ffnnoo--ppeeeepphhoollee and --ffnnoo--ppeeeepphhoollee22 is in how they are implemented in the compiler; some targets use one, some use the other, a few use both. --ffppeeeepphhoollee is enabled by default. --ffppeeeepphhoollee22 enabled at levels --OO22, --OO33, --OOss. --ffnnoo--gguueessss--bbrraanncchh--pprroobbaabbiilliittyy Do not guess branch probabilities using heuristics. GCC uses heuristics to guess branch probabilities if they are not provided by profiling feedback (--ffpprrooffiillee--aarrccss). These heuristics are based on the control flow graph. If some branch probabilities are specified by "__builtin_expect", then the heuristics are used to guess branch probabilities for the rest of the control flow graph, taking the "__builtin_expect" info into account. The inter- actions between the heuristics and "__builtin_expect" can be com- plex, and in some cases, it may be useful to disable the heuristics so that the effects of "__builtin_expect" are easier to understand. It is also possible to specify expected probability of the expres- sion with "__builtin_expect_with_probability" built-in function. The default is --ffgguueessss--bbrraanncchh--pprroobbaabbiilliittyy at levels --OO, --OO22, --OO33, --OOss. --ffrreeoorrddeerr--bblloocckkss Reorder basic blocks in the compiled function in order to reduce number of taken branches and improve code locality. Enabled at levels --OO11, --OO22, --OO33, --OOss. --ffrreeoorrddeerr--bblloocckkss--aallggoorriitthhmm==_a_l_g_o_r_i_t_h_m Use the specified algorithm for basic block reordering. The _a_l_g_o_- _r_i_t_h_m argument can be ssiimmppllee, which does not increase code size (except sometimes due to secondary effects like alignment), or ssttcc, the "software trace cache" algorithm, which tries to put all often executed code together, minimizing the number of branches executed by making extra copies of code. The default is ssiimmppllee at levels --OO11, --OOss, and ssttcc at levels --OO22, --OO33. --ffrreeoorrddeerr--bblloocckkss--aanndd--ppaarrttiittiioonn In addition to reordering basic blocks in the compiled function, in order to reduce number of taken branches, partitions hot and cold basic blocks into separate sections of the assembly and _._o files, to improve paging and cache locality performance. This optimization is automatically turned off in the presence of exception handling or unwind tables (on targets using setjump/longjump or target specific scheme), for linkonce sections, for functions with a user-defined section attribute and on any ar- chitecture that does not support named sections. When --ffss-- pplliitt--ssttaacckk is used this option is not enabled by default (to avoid linker errors), but may be enabled explicitly (if using a working linker). Enabled for x86 at levels --OO22, --OO33, --OOss. --ffrreeoorrddeerr--ffuunnccttiioonnss Reorder functions in the object file in order to improve code lo- cality. This is implemented by using special subsections ".text.hot" for most frequently executed functions and ".text.un- likely" for unlikely executed functions. Reordering is done by the linker so object file format must support named sections and linker must place them in a reasonable way. This option isn't effective unless you either provide profile feed- back (see --ffpprrooffiillee--aarrccss for details) or manually annotate func- tions with "hot" or "cold" attributes. Enabled at levels --OO22, --OO33, --OOss. --ffssttrriicctt--aalliiaassiinngg Allow the compiler to assume the strictest aliasing rules applica- ble to the language being compiled. For C (and C++), this acti- vates optimizations based on the type of expressions. In particu- lar, an object of one type is assumed never to reside at the same address as an object of a different type, unless the types are al- most the same. For example, an "unsigned int" can alias an "int", but not a "void*" or a "double". A character type may alias any other type. Pay special attention to code like this: union a_union { int i; double d; }; int f() { union a_union t; t.d = 3.0; return t.i; } The practice of reading from a different union member than the one most recently written to (called "type-punning") is common. Even with --ffssttrriicctt--aalliiaassiinngg, type-punning is allowed, provided the mem- ory is accessed through the union type. So, the code above works as expected. However, this code might not: int f() { union a_union t; int* ip; t.d = 3.0; ip = &t.i; return *ip; } Similarly, access by taking the address, casting the resulting pointer and dereferencing the result has undefined behavior, even if the cast uses a union type, e.g.: int f() { double d = 3.0; return ((union a_union *) &d)->i; } The --ffssttrriicctt--aalliiaassiinngg option is enabled at levels --OO22, --OO33, --OOss. --ffiippaa--ssttrriicctt--aalliiaassiinngg Controls whether rules of --ffssttrriicctt--aalliiaassiinngg are applied across function boundaries. Note that if multiple functions gets inlined into a single function the memory accesses are no longer considered to be crossing a function boundary. The --ffiippaa--ssttrriicctt--aalliiaassiinngg option is enabled by default and is ef- fective only in combination with --ffssttrriicctt--aalliiaassiinngg. --ffaalliiggnn--ffuunnccttiioonnss --ffaalliiggnn--ffuunnccttiioonnss==_n --ffaalliiggnn--ffuunnccttiioonnss==_n::_m --ffaalliiggnn--ffuunnccttiioonnss==_n::_m::_n_2 --ffaalliiggnn--ffuunnccttiioonnss==_n::_m::_n_2::_m_2 Align the start of functions to the next power-of-two greater than or equal to _n, skipping up to _m-1 bytes. This ensures that at least the first _m bytes of the function can be fetched by the CPU without crossing an _n-byte alignment boundary. If _m is not specified, it defaults to _n. Examples: --ffaalliiggnn--ffuunnccttiioonnss==3322 aligns functions to the next 32-byte boundary, --ffaalliiggnn--ffuunnccttiioonnss==2244 aligns to the next 32-byte boundary only if this can be done by skipping 23 bytes or less, --ffaalliiggnn--ffuunnccttiioonnss==3322::77 aligns to the next 32-byte boundary only if this can be done by skipping 6 bytes or less. The second pair of _n_2:_m_2 values allows you to specify a secondary alignment: --ffaalliiggnn--ffuunnccttiioonnss==6644::77::3322::33 aligns to the next 64-byte boundary if this can be done by skipping 6 bytes or less, otherwise aligns to the next 32-byte boundary if this can be done by skipping 2 bytes or less. If _m_2 is not specified, it defaults to _n_2. Some assemblers only support this flag when _n is a power of two; in that case, it is rounded up. --ffnnoo--aalliiggnn--ffuunnccttiioonnss and --ffaalliiggnn--ffuunnccttiioonnss==11 are equivalent and mean that functions are not aligned. If _n is not specified or is zero, use a machine-dependent default. The maximum allowed _n option value is 65536. Enabled at levels --OO22, --OO33. --fflliimmiitt--ffuunnccttiioonn--aalliiggnnmmeenntt If this option is enabled, the compiler tries to avoid unnecessar- ily overaligning functions. It attempts to instruct the assembler to align by the amount specified by --ffaalliiggnn--ffuunnccttiioonnss, but not to skip more bytes than the size of the function. --ffaalliiggnn--llaabbeellss --ffaalliiggnn--llaabbeellss==_n --ffaalliiggnn--llaabbeellss==_n::_m --ffaalliiggnn--llaabbeellss==_n::_m::_n_2 --ffaalliiggnn--llaabbeellss==_n::_m::_n_2::_m_2 Align all branch targets to a power-of-two boundary. Parameters of this option are analogous to the --ffaalliiggnn--ffuunnccttiioonnss option. --ffnnoo--aalliiggnn--llaabbeellss and --ffaalliiggnn--llaabbeellss==11 are equivalent and mean that labels are not aligned. If --ffaalliiggnn--llooooppss or --ffaalliiggnn--jjuummppss are applicable and are greater than this value, then their values are used instead. If _n is not specified or is zero, use a machine-dependent default which is very likely to be 11, meaning no alignment. The maximum allowed _n option value is 65536. Enabled at levels --OO22, --OO33. --ffaalliiggnn--llooooppss --ffaalliiggnn--llooooppss==_n --ffaalliiggnn--llooooppss==_n::_m --ffaalliiggnn--llooooppss==_n::_m::_n_2 --ffaalliiggnn--llooooppss==_n::_m::_n_2::_m_2 Align loops to a power-of-two boundary. If the loops are executed many times, this makes up for any execution of the dummy padding instructions. If --ffaalliiggnn--llaabbeellss is greater than this value, then its value is used instead. Parameters of this option are analogous to the --ffaalliiggnn--ffuunnccttiioonnss option. --ffnnoo--aalliiggnn--llooooppss and --ffaalliiggnn--llooooppss==11 are equivalent and mean that loops are not aligned. The maximum allowed _n option value is 65536. If _n is not specified or is zero, use a machine-dependent default. Enabled at levels --OO22, --OO33. --ffaalliiggnn--jjuummppss --ffaalliiggnn--jjuummppss==_n --ffaalliiggnn--jjuummppss==_n::_m --ffaalliiggnn--jjuummppss==_n::_m::_n_2 --ffaalliiggnn--jjuummppss==_n::_m::_n_2::_m_2 Align branch targets to a power-of-two boundary, for branch targets where the targets can only be reached by jumping. In this case, no dummy operations need be executed. If --ffaalliiggnn--llaabbeellss is greater than this value, then its value is used instead. Parameters of this option are analogous to the --ffaalliiggnn--ffuunnccttiioonnss option. --ffnnoo--aalliiggnn--jjuummppss and --ffaalliiggnn--jjuummppss==11 are equivalent and mean that loops are not aligned. If _n is not specified or is zero, use a machine-dependent default. The maximum allowed _n option value is 65536. Enabled at levels --OO22, --OO33. --ffnnoo--aallllooccaattiioonn--ddccee Do not remove unused C++ allocations in dead code elimination. --ffaallllooww--ssttoorree--ddaattaa--rraacceess Allow the compiler to perform optimizations that may introduce new data races on stores, without proving that the variable cannot be concurrently accessed by other threads. Does not affect optimiza- tion of local data. It is safe to use this option if it is known that global data will not be accessed by multiple threads. Examples of optimizations enabled by --ffaallllooww--ssttoorree--ddaattaa--rraacceess in- clude hoisting or if-conversions that may cause a value that was already in memory to be re-written with that same value. Such re- writing is safe in a single threaded context but may be unsafe in a multi-threaded context. Note that on some processors, if-conver- sions may be required in order to enable vectorization. Enabled at level --OOffaasstt. --ffuunniitt--aatt--aa--ttiimmee This option is left for compatibility reasons. --ffuunniitt--aatt--aa--ttiimmee has no effect, while --ffnnoo--uunniitt--aatt--aa--ttiimmee implies --ffnnoo--ttoopplleevveell--rreeoorrddeerr and --ffnnoo--sseeccttiioonn--aanncchhoorrss. Enabled by default. --ffnnoo--ttoopplleevveell--rreeoorrddeerr Do not reorder top-level functions, variables, and "asm" state- ments. Output them in the same order that they appear in the input file. When this option is used, unreferenced static variables are not removed. This option is intended to support existing code that relies on a particular ordering. For new code, it is better to use attributes when possible. --ffttoopplleevveell--rreeoorrddeerr is the default at --OO11 and higher, and also at --OO00 if --ffsseeccttiioonn--aanncchhoorrss is explicitly requested. Additionally --ffnnoo--ttoopplleevveell--rreeoorrddeerr implies --ffnnoo--sseeccttiioonn--aanncchhoorrss. --ffwweebb Constructs webs as commonly used for register allocation purposes and assign each web individual pseudo register. This allows the register allocation pass to operate on pseudos directly, but also strengthens several other optimization passes, such as CSE, loop optimizer and trivial dead code remover. It can, however, make de- bugging impossible, since variables no longer stay in a "home reg- ister". Enabled by default with --ffuunnrroollll--llooooppss. --ffwwhhoollee--pprrooggrraamm Assume that the current compilation unit represents the whole pro- gram being compiled. All public functions and variables with the exception of "main" and those merged by attribute "externally_visi- ble" become static functions and in effect are optimized more ag- gressively by interprocedural optimizers. This option should not be used in combination with --ffllttoo. Instead relying on a linker plugin should provide safer and more precise information. --ffllttoo[[==_n]] This option runs the standard link-time optimizer. When invoked with source code, it generates GIMPLE (one of GCC's internal repre- sentations) and writes it to special ELF sections in the object file. When the object files are linked together, all the function bodies are read from these ELF sections and instantiated as if they had been part of the same translation unit. To use the link-time optimizer, --ffllttoo and optimization options should be specified at compile time and during the final link. It is recommended that you compile all the files participating in the same link with the same options and also specify those options at link time. For example: gcc -c -O2 -flto foo.c gcc -c -O2 -flto bar.c gcc -o myprog -flto -O2 foo.o bar.o The first two invocations to GCC save a bytecode representation of GIMPLE into special ELF sections inside _f_o_o_._o and _b_a_r_._o. The final invocation reads the GIMPLE bytecode from _f_o_o_._o and _b_a_r_._o, merges the two files into a single internal image, and compiles the result as usual. Since both _f_o_o_._o and _b_a_r_._o are merged into a single im- age, this causes all the interprocedural analyses and optimizations in GCC to work across the two files as if they were a single one. This means, for example, that the inliner is able to inline func- tions in _b_a_r_._o into functions in _f_o_o_._o and vice-versa. Another (simpler) way to enable link-time optimization is: gcc -o myprog -flto -O2 foo.c bar.c The above generates bytecode for _f_o_o_._c and _b_a_r_._c, merges them to- gether into a single GIMPLE representation and optimizes them as usual to produce _m_y_p_r_o_g. The important thing to keep in mind is that to enable link-time op- timizations you need to use the GCC driver to perform the link step. GCC automatically performs link-time optimization if any of the objects involved were compiled with the --ffllttoo command-line op- tion. You can always override the automatic decision to do link- time optimization by passing --ffnnoo--llttoo to the link command. To make whole program optimization effective, it is necessary to make certain whole program assumptions. The compiler needs to know what functions and variables can be accessed by libraries and run- time outside of the link-time optimized unit. When supported by the linker, the linker plugin (see --ffuussee--lliinnkkeerr--pplluuggiinn) passes in- formation to the compiler about used and externally visible sym- bols. When the linker plugin is not available, --ffwwhhoollee--pprrooggrraamm should be used to allow the compiler to make these assumptions, which leads to more aggressive optimization decisions. When a file is compiled with --ffllttoo without --ffuussee--lliinnkkeerr--pplluuggiinn, the generated object file is larger than a regular object file because it contains GIMPLE bytecodes and the usual final code (see --ffffaatt--llttoo--oobbjjeeccttss). This means that object files with LTO informa- tion can be linked as normal object files; if --ffnnoo--llttoo is passed to the linker, no interprocedural optimizations are applied. Note that when --ffnnoo--ffaatt--llttoo--oobbjjeeccttss is enabled the compile stage is faster but you cannot perform a regular, non-LTO link on them. When producing the final binary, GCC only applies link-time opti- mizations to those files that contain bytecode. Therefore, you can mix and match object files and libraries with GIMPLE bytecodes and final object code. GCC automatically selects which files to opti- mize in LTO mode and which files to link without further process- ing. Generally, options specified at link time override those specified at compile time, although in some cases GCC attempts to infer link- time options from the settings used to compile the input files. If you do not specify an optimization level option --OO at link time, then GCC uses the highest optimization level used when compiling the object files. Note that it is generally ineffective to specify an optimization level option only at link time and not at compile time, for two reasons. First, compiling without optimization sup- presses compiler passes that gather information needed for effec- tive optimization at link time. Second, some early optimization passes can be performed only at compile time and not at link time. There are some code generation flags preserved by GCC when generat- ing bytecodes, as they need to be used during the final link. Cur- rently, the following options and their settings are taken from the first object file that explicitly specifies them: --ffccoommmmoonn, --ffeexx-- cceeppttiioonnss, --ffnnoonn--ccaallll--eexxcceeppttiioonnss, --ffggnnuu--ttmm and all the --mm target flags. The following options --ffPPIICC, --ffppiicc, --ffppiiee and --ffPPIIEE are combined based on the following scheme: B<-fPIC> + B<-fpic> = B<-fpic> B<-fPIC> + B<-fno-pic> = B<-fno-pic> B<-fpic/-fPIC> + (no option) = (no option) B<-fPIC> + B<-fPIE> = B<-fPIE> B<-fpic> + B<-fPIE> = B<-fpie> B<-fPIC/-fpic> + B<-fpie> = B<-fpie> Certain ABI-changing flags are required to match in all compilation units, and trying to override this at link time with a conflicting value is ignored. This includes options such as --ffrreegg--ssttrruucctt--rree-- ttuurrnn and --ffppcccc--ssttrruucctt--rreettuurrnn. Other options such as --ffffpp--ccoonnttrraacctt, --ffnnoo--ssttrriicctt--oovveerrffllooww, --ffwwrraappvv, --ffnnoo--ttrraappvv or --ffnnoo--ssttrriicctt--aalliiaassiinngg are passed through to the link stage and merged conservatively for conflicting translation units. Specifically --ffnnoo--ssttrriicctt--oovveerrffllooww, --ffwwrraappvv and --ffnnoo--ttrraappvv take precedence; and for example --ffffpp--ccoonnttrraacctt==ooffff takes precedence over --ffffpp--ccoonnttrraacctt==ffaasstt. You can override them at link time. Diagnostic options such as --WWssttrriinnggoopp--oovveerrffllooww are passed through to the link stage and their setting matches that of the compile- step at function granularity. Note that this matters only for di- agnostics emitted during optimization. Note that code transforms such as inlining can lead to warnings being enabled or disabled for regions if code not consistent with the setting at compile time. When you need to pass options to the assembler via --WWaa or --XXaasssseemm-- bblleerr make sure to either compile such translation units with --ffnnoo--llttoo or consistently use the same assembler options on all translation units. You can alternatively also specify assembler options at LTO link time. To enable debug info generation you need to supply --gg at compile time. If any of the input files at link time were built with debug info generation enabled the link will enable debug info generation as well. Any elaborate debug info settings like the dwarf level --ggddwwaarrff--55 need to be explicitly repeated at the linker command line and mixing different settings in different translation units is discouraged. If LTO encounters objects with C linkage declared with incompatible types in separate translation units to be linked together (unde- fined behavior according to ISO C99 6.2.7), a non-fatal diagnostic may be issued. The behavior is still undefined at run time. Simi- lar diagnostics may be raised for other languages. Another feature of LTO is that it is possible to apply interproce- dural optimizations on files written in different languages: gcc -c -flto foo.c g++ -c -flto bar.cc gfortran -c -flto baz.f90 g++ -o myprog -flto -O3 foo.o bar.o baz.o -lgfortran Notice that the final link is done with gg++++ to get the C++ runtime libraries and --llggffoorrttrraann is added to get the Fortran runtime li- braries. In general, when mixing languages in LTO mode, you should use the same link command options as when mixing languages in a regular (non-LTO) compilation. If object files containing GIMPLE bytecode are stored in a library archive, say _l_i_b_f_o_o_._a, it is possible to extract and use them in an LTO link if you are using a linker with plugin support. To create static libraries suitable for LTO, use ggcccc--aarr and ggcccc--rraannlliibb in- stead of aarr and rraannlliibb; to show the symbols of object files with GIMPLE bytecode, use ggcccc--nnmm. Those commands require that aarr, rraann-- lliibb and nnmm have been compiled with plugin support. At link time, use the flag --ffuussee--lliinnkkeerr--pplluuggiinn to ensure that the library partic- ipates in the LTO optimization process: gcc -o myprog -O2 -flto -fuse-linker-plugin a.o b.o -lfoo With the linker plugin enabled, the linker extracts the needed GIM- PLE files from _l_i_b_f_o_o_._a and passes them on to the running GCC to make them part of the aggregated GIMPLE image to be optimized. If you are not using a linker with plugin support and/or do not en- able the linker plugin, then the objects inside _l_i_b_f_o_o_._a are ex- tracted and linked as usual, but they do not participate in the LTO optimization process. In order to make a static library suitable for both LTO optimization and usual linkage, compile its object files with --ffllttoo --ffffaatt--llttoo--oobbjjeeccttss. Link-time optimizations do not require the presence of the whole program to operate. If the program does not require any symbols to be exported, it is possible to combine --ffllttoo and --ffwwhhoollee--pprrooggrraamm to allow the interprocedural optimizers to use more aggressive assump- tions which may lead to improved optimization opportunities. Use of --ffwwhhoollee--pprrooggrraamm is not needed when linker plugin is active (see --ffuussee--lliinnkkeerr--pplluuggiinn). The current implementation of LTO makes no attempt to generate bytecode that is portable between different types of hosts. The bytecode files are versioned and there is a strict version check, so bytecode files generated in one version of GCC do not work with an older or newer version of GCC. Link-time optimization does not work well with generation of debug- ging information on systems other than those using a combination of ELF and DWARF. If you specify the optional _n, the optimization and code generation done at link time is executed in parallel using _n parallel jobs by utilizing an installed mmaakkee program. The environment variable MMAAKKEE may be used to override the program used. You can also specify --ffllttoo==jjoobbsseerrvveerr to use GNU make's job server mode to determine the number of parallel jobs. This is useful when the Makefile calling GCC is already executing in parallel. You must prepend a ++ to the command recipe in the parent Makefile for this to work. This option likely only works if MMAAKKEE is GNU make. Even without the option value, GCC tries to automatically detect a running GNU make's job server. Use --ffllttoo==aauuttoo to use GNU make's job server, if available, or oth- erwise fall back to autodetection of the number of CPU threads present in your system. --ffllttoo--ppaarrttiittiioonn==_a_l_g Specify the partitioning algorithm used by the link-time optimizer. The value is either 11ttoo11 to specify a partitioning mirroring the original source files or bbaallaanncceedd to specify partitioning into equally sized chunks (whenever possible) or mmaaxx to create new par- tition for every symbol where possible. Specifying nnoonnee as an al- gorithm disables partitioning and streaming completely. The de- fault value is bbaallaanncceedd. While 11ttoo11 can be used as an workaround for various code ordering issues, the mmaaxx partitioning is intended for internal testing only. The value oonnee specifies that exactly one partition should be used while the value nnoonnee bypasses parti- tioning and executes the link-time optimization step directly from the WPA phase. --ffllttoo--ccoommpprreessssiioonn--lleevveell==_n This option specifies the level of compression used for intermedi- ate language written to LTO object files, and is only meaningful in conjunction with LTO mode (--ffllttoo). GCC currently supports two LTO compression algorithms. For zstd, valid values are 0 (no compres- sion) to 19 (maximum compression), while zlib supports values from 0 to 9. Values outside this range are clamped to either minimum or maximum of the supported values. If the option is not given, a de- fault balanced compression setting is used. --ffuussee--lliinnkkeerr--pplluuggiinn Enables the use of a linker plugin during link-time optimization. This option relies on plugin support in the linker, which is avail- able in gold or in GNU ld 2.21 or newer. This option enables the extraction of object files with GIMPLE bytecode out of library archives. This improves the quality of op- timization by exposing more code to the link-time optimizer. This information specifies what symbols can be accessed externally (by non-LTO object or during dynamic linking). Resulting code quality improvements on binaries (and shared libraries that use hidden vis- ibility) are similar to --ffwwhhoollee--pprrooggrraamm. See --ffllttoo for a descrip- tion of the effect of this flag and how to use it. This option is enabled by default when LTO support in GCC is en- abled and GCC was configured for use with a linker supporting plug- ins (GNU ld 2.21 or newer or gold). --ffffaatt--llttoo--oobbjjeeccttss Fat LTO objects are object files that contain both the intermediate language and the object code. This makes them usable for both LTO linking and normal linking. This option is effective only when com- piling with --ffllttoo and is ignored at link time. --ffnnoo--ffaatt--llttoo--oobbjjeeccttss improves compilation time over plain LTO, but requires the complete toolchain to be aware of LTO. It requires a linker with linker plugin support for basic functionality. Addi- tionally, nnmm, aarr and rraannlliibb need to support linker plugins to allow a full-featured build environment (capable of building static li- braries etc). GCC provides the ggcccc--aarr, ggcccc--nnmm, ggcccc--rraannlliibb wrappers to pass the right options to these tools. With non fat LTO make- files need to be modified to use them. Note that modern binutils provide plugin auto-load mechanism. In- stalling the linker plugin into _$_l_i_b_d_i_r_/_b_f_d_-_p_l_u_g_i_n_s has the same effect as usage of the command wrappers (ggcccc--aarr, ggcccc--nnmm and ggcccc-- rraannlliibb). The default is --ffnnoo--ffaatt--llttoo--oobbjjeeccttss on targets with linker plugin support. --ffccoommppaarree--eelliimm After register allocation and post-register allocation instruction splitting, identify arithmetic instructions that compute processor flags similar to a comparison operation based on that arithmetic. If possible, eliminate the explicit comparison operation. This pass only applies to certain targets that cannot explicitly represent the comparison operation before register allocation is complete. Enabled at levels --OO11, --OO22, --OO33, --OOss. --ffccpprroopp--rreeggiisstteerrss After register allocation and post-register allocation instruction splitting, perform a copy-propagation pass to try to reduce sched- uling dependencies and occasionally eliminate the copy. Enabled at levels --OO11, --OO22, --OO33, --OOss. --ffpprrooffiillee--ccoorrrreeccttiioonn Profiles collected using an instrumented binary for multi-threaded programs may be inconsistent due to missed counter updates. When this option is specified, GCC uses heuristics to correct or smooth out such inconsistencies. By default, GCC emits an error message when an inconsistent profile is detected. This option is enabled by --ffaauuttoo--pprrooffiillee. --ffpprrooffiillee--ppaarrttiiaall--ttrraaiinniinngg With "-fprofile-use" all portions of programs not executed during train run are optimized agressively for size rather than speed. In some cases it is not practical to train all possible hot paths in the program. (For example, program may contain functions specific for a given hardware and trianing may not cover all hardware con- figurations program is run on.) With "-fprofile-partial-training" profile feedback will be ignored for all functions not executed during the train run leading them to be optimized as if they were compiled without profile feedback. This leads to better performance when train run is not representative but also leads to signifi- cantly bigger code. --ffpprrooffiillee--uussee --ffpprrooffiillee--uussee==_p_a_t_h Enable profile feedback-directed optimizations, and the following optimizations, many of which are generally profitable only with profile feedback available: --ffbbrraanncchh--pprroobbaabbiilliittiieess --ffpprrooffiillee--vvaalluueess --ffuunnrroollll--llooooppss --ffppeeeell--llooooppss --ffttrraacceerr --ffvvpptt --ffiinnlliinnee--ffuunnccttiioonnss --ffiippaa--ccpp --ffiippaa--ccpp--cclloonnee --ffiippaa--bbiitt--ccpp --ffpprreeddiiccttiivvee--ccoommmmoonniinngg --ffsspplliitt--llooooppss --ffuunnsswwiittcchh--llooooppss --ffggccssee--aafftteerr--rreellooaadd --ffttrreeee--lloooopp--vveeccttoorriizzee --ffttrreeee--ssllpp--vveeccttoorriizzee --ffvveecctt--ccoosstt--mmooddeell==ddyynnaammiicc --ffttrreeee--lloooopp--ddiiss-- ttrriibbuuttee--ppaatttteerrnnss --ffpprrooffiillee--rreeoorrddeerr--ffuunnccttiioonnss Before you can use this option, you must first generate profiling information. By default, GCC emits an error message if the feedback profiles do not match the source code. This error can be turned into a warning by using --WWnnoo--eerrrroorr==ccoovveerraaggee--mmiissmmaattcchh. Note this may result in poorly optimized code. Additionally, by default, GCC also emits a warning message if the feedback profiles do not exist (see --WWmmiissss-- iinngg--pprrooffiillee). If _p_a_t_h is specified, GCC looks at the _p_a_t_h to find the profile feedback data files. See --ffpprrooffiillee--ddiirr. --ffaauuttoo--pprrooffiillee --ffaauuttoo--pprrooffiillee==_p_a_t_h Enable sampling-based feedback-directed optimizations, and the fol- lowing optimizations, many of which are generally profitable only with profile feedback available: --ffbbrraanncchh--pprroobbaabbiilliittiieess --ffpprrooffiillee--vvaalluueess --ffuunnrroollll--llooooppss --ffppeeeell--llooooppss --ffttrraacceerr --ffvvpptt --ffiinnlliinnee--ffuunnccttiioonnss --ffiippaa--ccpp --ffiippaa--ccpp--cclloonnee --ffiippaa--bbiitt--ccpp --ffpprreeddiiccttiivvee--ccoommmmoonniinngg --ffsspplliitt--llooooppss --ffuunnsswwiittcchh--llooooppss --ffggccssee--aafftteerr--rreellooaadd --ffttrreeee--lloooopp--vveeccttoorriizzee --ffttrreeee--ssllpp--vveeccttoorriizzee --ffvveecctt--ccoosstt--mmooddeell==ddyynnaammiicc --ffttrreeee--lloooopp--ddiiss-- ttrriibbuuttee--ppaatttteerrnnss --ffpprrooffiillee--ccoorrrreeccttiioonn _p_a_t_h is the name of a file containing AutoFDO profile information. If omitted, it defaults to _f_b_d_a_t_a_._a_f_d_o in the current directory. Producing an AutoFDO profile data file requires running your pro- gram with the ppeerrff utility on a supported GNU/Linux target system. For more information, see . E.g. perf record -e br_inst_retired:near_taken -b -o perf.data \ -- your_program Then use the ccrreeaattee__ggccoovv tool to convert the raw profile data to a format that can be used by GCC. You must also supply the un- stripped binary for your program to this tool. See . E.g. create_gcov --binary=your_program.unstripped --profile=perf.data \ --gcov=profile.afdo The following options control compiler behavior regarding floating- point arithmetic. These options trade off between speed and correct- ness. All must be specifically enabled. --ffffllooaatt--ssttoorree Do not store floating-point variables in registers, and inhibit other options that might change whether a floating-point value is taken from a register or memory. This option prevents undesirable excess precision on machines such as the 68000 where the floating registers (of the 68881) keep more precision than a "double" is supposed to have. Similarly for the x86 architecture. For most programs, the excess precision does only good, but a few programs rely on the precise definition of IEEE floating point. Use --ffffllooaatt--ssttoorree for such programs, after modifying them to store all pertinent intermediate computations into variables. --ffeexxcceessss--pprreecciissiioonn==_s_t_y_l_e This option allows further control over excess precision on ma- chines where floating-point operations occur in a format with more precision or range than the IEEE standard and interchange floating- point types. By default, --ffeexxcceessss--pprreecciissiioonn==ffaasstt is in effect; this means that operations may be carried out in a wider precision than the types specified in the source if that would result in faster code, and it is unpredictable when rounding to the types specified in the source code takes place. When compiling C, if --ffeexxcceessss--pprreecciissiioonn==ssttaannddaarrdd is specified then excess precision fol- lows the rules specified in ISO C99; in particular, both casts and assignments cause values to be rounded to their semantic types (whereas --ffffllooaatt--ssttoorree only affects assignments). This option is enabled by default for C if a strict conformance option such as --ssttdd==cc9999 is used. --ffffaasstt--mmaatthh enables --ffeexxcceessss--pprreecciissiioonn==ffaasstt by default regardless of whether a strict conformance option is used. --ffeexxcceessss--pprreecciissiioonn==ssttaannddaarrdd is not implemented for languages other than C. On the x86, it has no effect if --mmffppmmaatthh==ssssee or --mmffpp-- mmaatthh==ssssee++338877 is specified; in the former case, IEEE semantics apply without excess precision, and in the latter, rounding is unpre- dictable. --ffffaasstt--mmaatthh Sets the options --ffnnoo--mmaatthh--eerrrrnnoo, --ffuunnssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss, --ffffiinniittee--mmaatthh--oonnllyy, --ffnnoo--rroouunnddiinngg--mmaatthh, --ffnnoo--ssiiggnnaalliinngg--nnaannss, --ffccxx--lliimmiitteedd--rraannggee and --ffeexxcceessss--pprreecciissiioonn==ffaasstt. This option causes the preprocessor macro "__FAST_MATH__" to be de- fined. This option is not turned on by any --OO option besides --OOffaasstt since it can result in incorrect output for programs that depend on an exact implementation of IEEE or ISO rules/specifications for math functions. It may, however, yield faster code for programs that do not require the guarantees of these specifications. --ffnnoo--mmaatthh--eerrrrnnoo Do not set "errno" after calling math functions that are executed with a single instruction, e.g., "sqrt". A program that relies on IEEE exceptions for math error handling may want to use this flag for speed while maintaining IEEE arithmetic compatibility. This option is not turned on by any --OO option since it can result in incorrect output for programs that depend on an exact implemen- tation of IEEE or ISO rules/specifications for math functions. It may, however, yield faster code for programs that do not require the guarantees of these specifications. The default is --ffmmaatthh--eerrrrnnoo. On Darwin systems, the math library never sets "errno". There is therefore no reason for the compiler to consider the possibility that it might, and --ffnnoo--mmaatthh--eerrrrnnoo is the default. --ffuunnssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss Allow optimizations for floating-point arithmetic that (a) assume that arguments and results are valid and (b) may violate IEEE or ANSI standards. When used at link time, it may include libraries or startup files that change the default FPU control word or other similar optimizations. This option is not turned on by any --OO option since it can result in incorrect output for programs that depend on an exact implemen- tation of IEEE or ISO rules/specifications for math functions. It may, however, yield faster code for programs that do not require the guarantees of these specifications. Enables --ffnnoo--ssiiggnneedd--zzeerrooss, --ffnnoo--ttrraappppiinngg--mmaatthh, --ffaassssoocciiaattiivvee--mmaatthh and --ffrreecciipprrooccaall--mmaatthh. The default is --ffnnoo--uunnssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss. --ffaassssoocciiaattiivvee--mmaatthh Allow re-association of operands in series of floating-point opera- tions. This violates the ISO C and C++ language standard by possi- bly changing computation result. NOTE: re-ordering may change the sign of zero as well as ignore NaNs and inhibit or create underflow or overflow (and thus cannot be used on code that relies on round- ing behavior like "(x + 2**52) - 2**52". May also reorder float- ing-point comparisons and thus may not be used when ordered compar- isons are required. This option requires that both --ffnnoo--ssiiggnneedd--zzee-- rrooss and --ffnnoo--ttrraappppiinngg--mmaatthh be in effect. Moreover, it doesn't make much sense with --ffrroouunnddiinngg--mmaatthh. For Fortran the option is automat- ically enabled when both --ffnnoo--ssiiggnneedd--zzeerrooss and --ffnnoo--ttrraappppiinngg--mmaatthh are in effect. The default is --ffnnoo--aassssoocciiaattiivvee--mmaatthh. --ffrreecciipprrooccaall--mmaatthh Allow the reciprocal of a value to be used instead of dividing by the value if this enables optimizations. For example "x / y" can be replaced with "x * (1/y)", which is useful if "(1/y)" is subject to common subexpression elimination. Note that this loses preci- sion and increases the number of flops operating on the value. The default is --ffnnoo--rreecciipprrooccaall--mmaatthh. --ffffiinniittee--mmaatthh--oonnllyy Allow optimizations for floating-point arithmetic that assume that arguments and results are not NaNs or +-Infs. This option is not turned on by any --OO option since it can result in incorrect output for programs that depend on an exact implemen- tation of IEEE or ISO rules/specifications for math functions. It may, however, yield faster code for programs that do not require the guarantees of these specifications. The default is --ffnnoo--ffiinniittee--mmaatthh--oonnllyy. --ffnnoo--ssiiggnneedd--zzeerrooss Allow optimizations for floating-point arithmetic that ignore the signedness of zero. IEEE arithmetic specifies the behavior of dis- tinct +0.0 and -0.0 values, which then prohibits simplification of expressions such as x+0.0 or 0.0*x (even with --ffffiinniittee--mmaatthh--oonnllyy). This option implies that the sign of a zero result isn't signifi- cant. The default is --ffssiiggnneedd--zzeerrooss. --ffnnoo--ttrraappppiinngg--mmaatthh Compile code assuming that floating-point operations cannot gener- ate user-visible traps. These traps include division by zero, overflow, underflow, inexact result and invalid operation. This option requires that --ffnnoo--ssiiggnnaalliinngg--nnaannss be in effect. Setting this option may allow faster code if one relies on "non-stop" IEEE arithmetic, for example. This option should never be turned on by any --OO option since it can result in incorrect output for programs that depend on an exact im- plementation of IEEE or ISO rules/specifications for math func- tions. The default is --ffttrraappppiinngg--mmaatthh. --ffrroouunnddiinngg--mmaatthh Disable transformations and optimizations that assume default floating-point rounding behavior. This is round-to-zero for all floating point to integer conversions, and round-to-nearest for all other arithmetic truncations. This option should be specified for programs that change the FP rounding mode dynamically, or that may be executed with a non-default rounding mode. This option disables constant folding of floating-point expressions at compile time (which may be affected by rounding mode) and arithmetic transforma- tions that are unsafe in the presence of sign-dependent rounding modes. The default is --ffnnoo--rroouunnddiinngg--mmaatthh. This option is experimental and does not currently guarantee to disable all GCC optimizations that are affected by rounding mode. Future versions of GCC may provide finer control of this setting using C99's "FENV_ACCESS" pragma. This command-line option will be used to specify the default state for "FENV_ACCESS". --ffssiiggnnaalliinngg--nnaannss Compile code assuming that IEEE signaling NaNs may generate user- visible traps during floating-point operations. Setting this op- tion disables optimizations that may change the number of excep- tions visible with signaling NaNs. This option implies --ffttrraapp-- ppiinngg--mmaatthh. This option causes the preprocessor macro "__SUPPORT_SNAN__" to be defined. The default is --ffnnoo--ssiiggnnaalliinngg--nnaannss. This option is experimental and does not currently guarantee to disable all GCC optimizations that affect signaling NaN behavior. --ffnnoo--ffpp--iinntt--bbuuiillttiinn--iinneexxaacctt Do not allow the built-in functions "ceil", "floor", "round" and "trunc", and their "float" and "long double" variants, to generate code that raises the "inexact" floating-point exception for nonin- teger arguments. ISO C99 and C11 allow these functions to raise the "inexact" exception, but ISO/IEC TS 18661-1:2014, the C bind- ings to IEEE 754-2008, as integrated into ISO C2X, does not allow these functions to do so. The default is --ffffpp--iinntt--bbuuiillttiinn--iinneexxaacctt, allowing the exception to be raised, unless C2X or a later C standard is selected. This op- tion does nothing unless --ffttrraappppiinngg--mmaatthh is in effect. Even if --ffnnoo--ffpp--iinntt--bbuuiillttiinn--iinneexxaacctt is used, if the functions gen- erate a call to a library function then the "inexact" exception may be raised if the library implementation does not follow TS 18661. --ffssiinnggllee--pprreecciissiioonn--ccoonnssttaanntt Treat floating-point constants as single precision instead of im- plicitly converting them to double-precision constants. --ffccxx--lliimmiitteedd--rraannggee When enabled, this option states that a range reduction step is not needed when performing complex division. Also, there is no check- ing whether the result of a complex multiplication or division is "NaN + I*NaN", with an attempt to rescue the situation in that case. The default is --ffnnoo--ccxx--lliimmiitteedd--rraannggee, but is enabled by --ffffaasstt--mmaatthh. This option controls the default setting of the ISO C99 "CX_LIM- ITED_RANGE" pragma. Nevertheless, the option applies to all lan- guages. --ffccxx--ffoorrttrraann--rruulleess Complex multiplication and division follow Fortran rules. Range reduction is done as part of complex division, but there is no checking whether the result of a complex multiplication or division is "NaN + I*NaN", with an attempt to rescue the situation in that case. The default is --ffnnoo--ccxx--ffoorrttrraann--rruulleess. The following options control optimizations that may improve perfor- mance, but are not enabled by any --OO options. This section includes experimental options that may produce broken code. --ffbbrraanncchh--pprroobbaabbiilliittiieess After running a program compiled with --ffpprrooffiillee--aarrccss, you can com- pile it a second time using --ffbbrraanncchh--pprroobbaabbiilliittiieess, to improve op- timizations based on the number of times each branch was taken. When a program compiled with --ffpprrooffiillee--aarrccss exits, it saves arc ex- ecution counts to a file called _s_o_u_r_c_e_n_a_m_e_._g_c_d_a for each source file. The information in this data file is very dependent on the structure of the generated code, so you must use the same source code and the same optimization options for both compilations. See details about the file naming in --ffpprrooffiillee--aarrccss. With --ffbbrraanncchh--pprroobbaabbiilliittiieess, GCC puts a RREEGG__BBRR__PPRROOBB note on each JJUUMMPP__IINNSSNN and CCAALLLL__IINNSSNN. These can be used to improve optimiza- tion. Currently, they are only used in one place: in _r_e_o_r_g_._c_c, in- stead of guessing which path a branch is most likely to take, the RREEGG__BBRR__PPRROOBB values are used to exactly determine which path is taken more often. Enabled by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --ffpprrooffiillee--vvaalluueess If combined with --ffpprrooffiillee--aarrccss, it adds code so that some data about values of expressions in the program is gathered. With --ffbbrraanncchh--pprroobbaabbiilliittiieess, it reads back the data gathered from profiling values of expressions for usage in optimizations. Enabled by --ffpprrooffiillee--ggeenneerraattee, --ffpprrooffiillee--uussee, and --ffaauuttoo--pprrooffiillee. --ffpprrooffiillee--rreeoorrddeerr--ffuunnccttiioonnss Function reordering based on profile instrumentation collects first time of execution of a function and orders these functions in as- cending order. Enabled with --ffpprrooffiillee--uussee. --ffvvpptt If combined with --ffpprrooffiillee--aarrccss, this option instructs the compiler to add code to gather information about values of expressions. With --ffbbrraanncchh--pprroobbaabbiilliittiieess, it reads back the data gathered and actually performs the optimizations based on them. Currently the optimizations include specialization of division operations using the knowledge about the value of the denominator. Enabled with --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --ffrreennaammee--rreeggiisstteerrss Attempt to avoid false dependencies in scheduled code by making use of registers left over after register allocation. This optimiza- tion most benefits processors with lots of registers. Depending on the debug information format adopted by the target, however, it can make debugging impossible, since variables no longer stay in a "home register". Enabled by default with --ffuunnrroollll--llooooppss. --ffsscchheedduullee--ffuussiioonn Performs a target dependent pass over the instruction stream to schedule instructions of same type together because target machine can execute them more efficiently if they are adjacent to each other in the instruction flow. Enabled at levels --OO22, --OO33, --OOss. --ffttrraacceerr Perform tail duplication to enlarge superblock size. This trans- formation simplifies the control flow of the function allowing other optimizations to do a better job. Enabled by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --ffuunnrroollll--llooooppss Unroll loops whose number of iterations can be determined at com- pile time or upon entry to the loop. --ffuunnrroollll--llooooppss implies --ffrree-- rruunn--ccssee--aafftteerr--lloooopp, --ffwweebb and --ffrreennaammee--rreeggiisstteerrss. It also turns on complete loop peeling (i.e. complete removal of loops with a small constant number of iterations). This option makes code larger, and may or may not make it run faster. Enabled by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --ffuunnrroollll--aallll--llooooppss Unroll all loops, even if their number of iterations is uncertain when the loop is entered. This usually makes programs run more slowly. --ffuunnrroollll--aallll--llooooppss implies the same options as --ffuunn-- rroollll--llooooppss. --ffppeeeell--llooooppss Peels loops for which there is enough information that they do not roll much (from profile feedback or static analysis). It also turns on complete loop peeling (i.e. complete removal of loops with small constant number of iterations). Enabled by --OO33, --ffpprrooffiillee--uussee, and --ffaauuttoo--pprrooffiillee. --ffmmoovvee--lloooopp--iinnvvaarriiaannttss Enables the loop invariant motion pass in the RTL loop optimizer. Enabled at level --OO11 and higher, except for --OOgg. --ffmmoovvee--lloooopp--ssttoorreess Enables the loop store motion pass in the GIMPLE loop optimizer. This moves invariant stores to after the end of the loop in ex- change for carrying the stored value in a register across the iter- ation. Note for this option to have an effect --ffttrreeee--lloooopp--iimm has to be enabled as well. Enabled at level --OO11 and higher, except for --OOgg. --ffsspplliitt--llooooppss Split a loop into two if it contains a condition that's always true for one side of the iteration space and false for the other. Enabled by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --ffuunnsswwiittcchh--llooooppss Move branches with loop invariant conditions out of the loop, with duplicates of the loop on both branches (modified according to re- sult of the condition). Enabled by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --ffvveerrssiioonn--llooooppss--ffoorr--ssttrriiddeess If a loop iterates over an array with a variable stride, create an- other version of the loop that assumes the stride is always one. For example: for (int i = 0; i < n; ++i) x[i * stride] = ...; becomes: if (stride == 1) for (int i = 0; i < n; ++i) x[i] = ...; else for (int i = 0; i < n; ++i) x[i * stride] = ...; This is particularly useful for assumed-shape arrays in Fortran where (for example) it allows better vectorization assuming con- tiguous accesses. This flag is enabled by default at --OO33. It is also enabled by --ffpprrooffiillee--uussee and --ffaauuttoo--pprrooffiillee. --ffffuunnccttiioonn--sseeccttiioonnss --ffddaattaa--sseeccttiioonnss Place each function or data item into its own section in the output file if the target supports arbitrary sections. The name of the function or the name of the data item determines the section's name in the output file. Use these options on systems where the linker can perform optimiza- tions to improve locality of reference in the instruction space. Most systems using the ELF object format have linkers with such op- timizations. On AIX, the linker rearranges sections (CSECTs) based on the call graph. The performance impact varies. Together with a linker garbage collection (linker ----ggcc--sseeccttiioonnss op- tion) these options may lead to smaller statically-linked executa- bles (after stripping). On ELF/DWARF systems these options do not degenerate the quality of the debug information. There could be issues with other object files/debug info formats. Only use these options when there are significant benefits from do- ing so. When you specify these options, the assembler and linker create larger object and executable files and are also slower. These options affect code generation. They prevent optimizations by the compiler and assembler using relative locations inside a translation unit since the locations are unknown until link time. An example of such an optimization is relaxing calls to short call instructions. --ffssttddaarrgg--oopptt Optimize the prologue of variadic argument functions with respect to usage of those arguments. --ffsseeccttiioonn--aanncchhoorrss Try to reduce the number of symbolic address calculations by using shared "anchor" symbols to address nearby objects. This transfor- mation can help to reduce the number of GOT entries and GOT ac- cesses on some targets. For example, the implementation of the following function "foo": static int a, b, c; int foo (void) { return a + b + c; } usually calculates the addresses of all three variables, but if you compile it with --ffsseeccttiioonn--aanncchhoorrss, it accesses the variables from a common anchor point instead. The effect is similar to the follow- ing pseudocode (which isn't valid C): int foo (void) { register int *xr = &x; return xr[&a - &x] + xr[&b - &x] + xr[&c - &x]; } Not all targets support this option. --ffzzeerroo--ccaallll--uusseedd--rreeggss==_c_h_o_i_c_e Zero call-used registers at function return to increase program se- curity by either mitigating Return-Oriented Programming (ROP) at- tacks or preventing information leakage through registers. The possible values of _c_h_o_i_c_e are the same as for the "zero_call_used_regs" attribute. The default is sskkiipp. You can control this behavior for a specific function by using the function attribute "zero_call_used_regs". ----ppaarraamm _n_a_m_e==_v_a_l_u_e In some places, GCC uses various constants to control the amount of optimization that is done. For example, GCC does not inline func- tions that contain more than a certain number of instructions. You can control some of these constants on the command line using the ----ppaarraamm option. The names of specific parameters, and the meaning of the values, are tied to the internals of the compiler, and are subject to change without notice in future releases. In order to get minimal, maximal and default value of a parameter, one can use ----hheellpp==ppaarraamm --QQ options. In each case, the _v_a_l_u_e is an integer. The following choices of _n_a_m_e are recognized for all targets: pprreeddiiccttaabbllee--bbrraanncchh--oouuttccoommee When branch is predicted to be taken with probability lower than this threshold (in percent), then it is considered well predictable. mmaaxx--rrttll--iiff--ccoonnvveerrssiioonn--iinnssnnss RTL if-conversion tries to remove conditional branches around a block and replace them with conditionally executed instruc- tions. This parameter gives the maximum number of instructions in a block which should be considered for if-conversion. The compiler will also use other heuristics to decide whether if- conversion is likely to be profitable. mmaaxx--rrttll--iiff--ccoonnvveerrssiioonn--pprreeddiiccttaabbllee--ccoosstt RTL if-conversion will try to remove conditional branches around a block and replace them with conditionally executed in- structions. These parameters give the maximum permissible cost for the sequence that would be generated by if-conversion de- pending on whether the branch is statically determined to be predictable or not. The units for this parameter are the same as those for the GCC internal seq_cost metric. The compiler will try to provide a reasonable default for this parameter us- ing the BRANCH_COST target macro. mmaaxx--ccrroossssjjuummpp--eeddggeess The maximum number of incoming edges to consider for cross-jumping. The algorithm used by --ffccrroossssjjuummppiinngg is O(N^2) in the number of edges incoming to each block. Increasing val- ues mean more aggressive optimization, making the compilation time increase with probably small improvement in executable size. mmiinn--ccrroossssjjuummpp--iinnssnnss The minimum number of instructions that must be matched at the end of two blocks before cross-jumping is performed on them. This value is ignored in the case where all instructions in the block being cross-jumped from are matched. mmaaxx--ggrrooww--ccooppyy--bbbb--iinnssnnss The maximum code size expansion factor when copying basic blocks instead of jumping. The expansion is relative to a jump instruction. mmaaxx--ggoottoo--dduupplliiccaattiioonn--iinnssnnss The maximum number of instructions to duplicate to a block that jumps to a computed goto. To avoid O(N^2) behavior in a number of passes, GCC factors computed gotos early in the compilation process, and unfactors them as late as possible. Only computed jumps at the end of a basic blocks with no more than max-goto- duplication-insns are unfactored. mmaaxx--ddeellaayy--sslloott--iinnssnn--sseeaarrcchh The maximum number of instructions to consider when looking for an instruction to fill a delay slot. If more than this arbi- trary number of instructions are searched, the time savings from filling the delay slot are minimal, so stop searching. Increasing values mean more aggressive optimization, making the compilation time increase with probably small improvement in execution time. mmaaxx--ddeellaayy--sslloott--lliivvee--sseeaarrcchh When trying to fill delay slots, the maximum number of instruc- tions to consider when searching for a block with valid live register information. Increasing this arbitrarily chosen value means more aggressive optimization, increasing the compilation time. This parameter should be removed when the delay slot code is rewritten to maintain the control-flow graph. mmaaxx--ggccssee--mmeemmoorryy The approximate maximum amount of memory in "kB" that can be allocated in order to perform the global common subexpression elimination optimization. If more memory than specified is re- quired, the optimization is not done. mmaaxx--ggccssee--iinnsseerrttiioonn--rraattiioo If the ratio of expression insertions to deletions is larger than this value for any expression, then RTL PRE inserts or re- moves the expression and thus leaves partially redundant compu- tations in the instruction stream. mmaaxx--ppeennddiinngg--lliisstt--lleennggtthh The maximum number of pending dependencies scheduling allows before flushing the current state and starting over. Large functions with few branches or calls can create excessively large lists which needlessly consume memory and resources. mmaaxx--mmoodduulloo--bbaacckkttrraacckk--aatttteemmppttss The maximum number of backtrack attempts the scheduler should make when modulo scheduling a loop. Larger values can exponen- tially increase compilation time. mmaaxx--iinnlliinnee--ffuunnccttiioonnss--ccaalllleedd--oonnccee--lloooopp--ddeepptthh Maximal loop depth of a call considered by inline heuristics that tries to inline all functions called once. mmaaxx--iinnlliinnee--ffuunnccttiioonnss--ccaalllleedd--oonnccee--iinnssnnss Maximal estimated size of functions produced while inlining functions called once. mmaaxx--iinnlliinnee--iinnssnnss--ssiinnggllee Several parameters control the tree inliner used in GCC. This number sets the maximum number of instructions (counted in GCC's internal representation) in a single function that the tree inliner considers for inlining. This only affects func- tions declared inline and methods implemented in a class decla- ration (C++). mmaaxx--iinnlliinnee--iinnssnnss--aauuttoo When you use --ffiinnlliinnee--ffuunnccttiioonnss (included in --OO33), a lot of functions that would otherwise not be considered for inlining by the compiler are investigated. To those functions, a dif- ferent (more restrictive) limit compared to functions declared inline can be applied (----ppaarraamm mmaaxx--iinnlliinnee--iinnssnnss--aauuttoo). mmaaxx--iinnlliinnee--iinnssnnss--ssmmaallll This is bound applied to calls which are considered relevant with --ffiinnlliinnee--ssmmaallll--ffuunnccttiioonnss. mmaaxx--iinnlliinnee--iinnssnnss--ssiizzee This is bound applied to calls which are optimized for size. Small growth may be desirable to anticipate optimization oppur- tunities exposed by inlining. uunniinnlliinneedd--ffuunnccttiioonn--iinnssnnss Number of instructions accounted by inliner for function over- head such as function prologue and epilogue. uunniinnlliinneedd--ffuunnccttiioonn--ttiimmee Extra time accounted by inliner for function overhead such as time needed to execute function prologue and epilogue. iinnlliinnee--hheeuurriissttiiccss--hhiinntt--ppeerrcceenntt The scale (in percents) applied to iinnlliinnee--iinnssnnss--ssiinnggllee, iinn-- lliinnee--iinnssnnss--ssiinnggllee--OO22, iinnlliinnee--iinnssnnss--aauuttoo when inline heuristics hints that inlining is very profitable (will enable later opti- mizations). uunniinnlliinneedd--tthhuunnkk--iinnssnnss uunniinnlliinneedd--tthhuunnkk--ttiimmee Same as ----ppaarraamm uunniinnlliinneedd--ffuunnccttiioonn--iinnssnnss and ----ppaarraamm uunniinnlliinneedd-- ffuunnccttiioonn--ttiimmee but applied to function thunks. iinnlliinnee--mmiinn--ssppeeeedduupp When estimated performance improvement of caller + callee run- time exceeds this threshold (in percent), the function can be inlined regardless of the limit on ----ppaarraamm mmaaxx--iinnlliinnee--iinnssnnss-- ssiinnggllee and ----ppaarraamm mmaaxx--iinnlliinnee--iinnssnnss--aauuttoo. llaarrggee--ffuunnccttiioonn--iinnssnnss The limit specifying really large functions. For functions larger than this limit after inlining, inlining is constrained by ----ppaarraamm llaarrggee--ffuunnccttiioonn--ggrroowwtthh. This parameter is useful primarily to avoid extreme compilation time caused by non-lin- ear algorithms used by the back end. llaarrggee--ffuunnccttiioonn--ggrroowwtthh Specifies maximal growth of large function caused by inlining in percents. For example, parameter value 100 limits large function growth to 2.0 times the original size. llaarrggee--uunniitt--iinnssnnss The limit specifying large translation unit. Growth caused by inlining of units larger than this limit is limited by ----ppaarraamm iinnlliinnee--uunniitt--ggrroowwtthh. For small units this might be too tight. For example, consider a unit consisting of function A that is inline and B that just calls A three times. If B is small rel- ative to A, the growth of unit is 300\% and yet such inlining is very sane. For very large units consisting of small inline- able functions, however, the overall unit growth limit is needed to avoid exponential explosion of code size. Thus for smaller units, the size is increased to ----ppaarraamm llaarrggee--uunniitt--iinn-- ssnnss before applying ----ppaarraamm iinnlliinnee--uunniitt--ggrroowwtthh. llaazzyy--mmoodduulleess Maximum number of concurrently open C++ module files when lazy loading. iinnlliinnee--uunniitt--ggrroowwtthh Specifies maximal overall growth of the compilation unit caused by inlining. For example, parameter value 20 limits unit growth to 1.2 times the original size. Cold functions (either marked cold via an attribute or by profile feedback) are not accounted into the unit size. iippaa--ccpp--uunniitt--ggrroowwtthh Specifies maximal overall growth of the compilation unit caused by interprocedural constant propagation. For example, parame- ter value 10 limits unit growth to 1.1 times the original size. iippaa--ccpp--llaarrggee--uunniitt--iinnssnnss The size of translation unit that IPA-CP pass considers large. llaarrggee--ssttaacckk--ffrraammee The limit specifying large stack frames. While inlining the algorithm is trying to not grow past this limit too much. llaarrggee--ssttaacckk--ffrraammee--ggrroowwtthh Specifies maximal growth of large stack frames caused by inlin- ing in percents. For example, parameter value 1000 limits large stack frame growth to 11 times the original size. mmaaxx--iinnlliinnee--iinnssnnss--rreeccuurrssiivvee mmaaxx--iinnlliinnee--iinnssnnss--rreeccuurrssiivvee--aauuttoo Specifies the maximum number of instructions an out-of-line copy of a self-recursive inline function can grow into by per- forming recursive inlining. ----ppaarraamm mmaaxx--iinnlliinnee--iinnssnnss--rreeccuurrssiivvee applies to functions de- clared inline. For functions not declared inline, recursive inlining happens only when --ffiinnlliinnee--ffuunnccttiioonnss (included in --OO33) is enabled; ----ppaarraamm mmaaxx--iinnlliinnee--iinnssnnss--rreeccuurrssiivvee--aauuttoo applies in- stead. mmaaxx--iinnlliinnee--rreeccuurrssiivvee--ddeepptthh mmaaxx--iinnlliinnee--rreeccuurrssiivvee--ddeepptthh--aauuttoo Specifies the maximum recursion depth used for recursive inlin- ing. ----ppaarraamm mmaaxx--iinnlliinnee--rreeccuurrssiivvee--ddeepptthh applies to functions de- clared inline. For functions not declared inline, recursive inlining happens only when --ffiinnlliinnee--ffuunnccttiioonnss (included in --OO33) is enabled; ----ppaarraamm mmaaxx--iinnlliinnee--rreeccuurrssiivvee--ddeepptthh--aauuttoo applies in- stead. mmiinn--iinnlliinnee--rreeccuurrssiivvee--pprroobbaabbiilliittyy Recursive inlining is profitable only for function having deep recursion in average and can hurt for function having little recursion depth by increasing the prologue size or complexity of function body to other optimizers. When profile feedback is available (see --ffpprrooffiillee--ggeenneerraattee) the actual recursion depth can be guessed from the probability that function recurses via a given call expression. This parameter limits inlining only to call expressions whose probability ex- ceeds the given threshold (in percents). eeaarrllyy--iinnlliinniinngg--iinnssnnss Specify growth that the early inliner can make. In effect it increases the amount of inlining for code having a large ab- straction penalty. mmaaxx--eeaarrllyy--iinnlliinneerr--iitteerraattiioonnss Limit of iterations of the early inliner. This basically bounds the number of nested indirect calls the early inliner can resolve. Deeper chains are still handled by late inlining. ccoommddaatt--sshhaarriinngg--pprroobbaabbiilliittyy Probability (in percent) that C++ inline function with comdat visibility are shared across multiple compilation units. mmooddrreeff--mmaaxx--bbaasseess mmooddrreeff--mmaaxx--rreeffss mmooddrreeff--mmaaxx--aacccceesssseess Specifies the maximal number of base pointers, references and accesses stored for a single function by mod/ref analysis. mmooddrreeff--mmaaxx--tteessttss Specifies the maxmal number of tests alias oracle can perform to disambiguate memory locations using the mod/ref information. This parameter ought to be bigger than ----ppaarraamm mmooddrreeff--mmaaxx--bbaasseess and ----ppaarraamm mmooddrreeff--mmaaxx--rreeffss. mmooddrreeff--mmaaxx--ddeepptthh Specifies the maximum depth of DFS walk used by modref escape analysis. Setting to 0 disables the analysis completely. mmooddrreeff--mmaaxx--eessccaappee--ppooiinnttss Specifies the maximum number of escape points tracked by modref per SSA-name. mmooddrreeff--mmaaxx--aaddjjuussttmmeennttss Specifies the maximum number the access range is enlarged dur- ing modref dataflow analysis. pprrooffiillee--ffuunncc--iinntteerrnnaall--iidd A parameter to control whether to use function internal id in profile database lookup. If the value is 0, the compiler uses an id that is based on function assembler name and filename, which makes old profile data more tolerant to source changes such as function reordering etc. mmiinn--vveecctt--lloooopp--bboouunndd The minimum number of iterations under which loops are not vec- torized when --ffttrreeee--vveeccttoorriizzee is used. The number of itera- tions after vectorization needs to be greater than the value specified by this option to allow vectorization. ggccssee--ccoosstt--ddiissttaannccee--rraattiioo Scaling factor in calculation of maximum distance an expression can be moved by GCSE optimizations. This is currently sup- ported only in the code hoisting pass. The bigger the ratio, the more aggressive code hoisting is with simple expressions, i.e., the expressions that have cost less than ggccssee--uunnrree-- ssttrriicctteedd--ccoosstt. Specifying 0 disables hoisting of simple ex- pressions. ggccssee--uunnrreessttrriicctteedd--ccoosstt Cost, roughly measured as the cost of a single typical machine instruction, at which GCSE optimizations do not constrain the distance an expression can travel. This is currently supported only in the code hoisting pass. The lesser the cost, the more aggressive code hoisting is. Specifying 0 allows all expres- sions to travel unrestricted distances. mmaaxx--hhooiisstt--ddeepptthh The depth of search in the dominator tree for expressions to hoist. This is used to avoid quadratic behavior in hoisting algorithm. The value of 0 does not limit on the search, but may slow down compilation of huge functions. mmaaxx--ttaaiill--mmeerrggee--ccoommppaarriissoonnss The maximum amount of similar bbs to compare a bb with. This is used to avoid quadratic behavior in tree tail merging. mmaaxx--ttaaiill--mmeerrggee--iitteerraattiioonnss The maximum amount of iterations of the pass over the function. This is used to limit compilation time in tree tail merging. ssttoorree--mmeerrggiinngg--aallllooww--uunnaalliiggnneedd Allow the store merging pass to introduce unaligned stores if it is legal to do so. mmaaxx--ssttoorreess--ttoo--mmeerrggee The maximum number of stores to attempt to merge into wider stores in the store merging pass. mmaaxx--ssttoorree--cchhaaiinnss--ttoo--ttrraacckk The maximum number of store chains to track at the same time in the attempt to merge them into wider stores in the store merg- ing pass. mmaaxx--ssttoorreess--ttoo--ttrraacckk The maximum number of stores to track at the same time in the attemt to to merge them into wider stores in the store merging pass. mmaaxx--uunnrroolllleedd--iinnssnnss The maximum number of instructions that a loop may have to be unrolled. If a loop is unrolled, this parameter also deter- mines how many times the loop code is unrolled. mmaaxx--aavveerraaggee--uunnrroolllleedd--iinnssnnss The maximum number of instructions biased by probabilities of their execution that a loop may have to be unrolled. If a loop is unrolled, this parameter also determines how many times the loop code is unrolled. mmaaxx--uunnrroollll--ttiimmeess The maximum number of unrollings of a single loop. mmaaxx--ppeeeelleedd--iinnssnnss The maximum number of instructions that a loop may have to be peeled. If a loop is peeled, this parameter also determines how many times the loop code is peeled. mmaaxx--ppeeeell--ttiimmeess The maximum number of peelings of a single loop. mmaaxx--ppeeeell--bbrraanncchheess The maximum number of branches on the hot path through the peeled sequence. mmaaxx--ccoommpplleetteellyy--ppeeeelleedd--iinnssnnss The maximum number of insns of a completely peeled loop. mmaaxx--ccoommpplleetteellyy--ppeeeell--ttiimmeess The maximum number of iterations of a loop to be suitable for complete peeling. mmaaxx--ccoommpplleetteellyy--ppeeeell--lloooopp--nneesstt--ddeepptthh The maximum depth of a loop nest suitable for complete peeling. mmaaxx--uunnsswwiittcchh--iinnssnnss The maximum number of insns of an unswitched loop. mmaaxx--uunnsswwiittcchh--lleevveell The maximum number of branches unswitched in a single loop. lliimm--eexxppeennssiivvee The minimum cost of an expensive expression in the loop invari- ant motion. mmiinn--lloooopp--ccoonndd--sspplliitt--pprroobb When FDO profile information is available, mmiinn--lloooopp--ccoonndd--sspplliitt-- pprroobb specifies minimum threshold for probability of semi-in- variant condition statement to trigger loop split. iivv--ccoonnssiiddeerr--aallll--ccaannddiiddaatteess--bboouunndd Bound on number of candidates for induction variables, below which all candidates are considered for each use in induction variable optimizations. If there are more candidates than this, only the most relevant ones are considered to avoid qua- dratic time complexity. iivv--mmaaxx--ccoonnssiiddeerreedd--uusseess The induction variable optimizations give up on loops that con- tain more induction variable uses. iivv--aallwwaayyss--pprruunnee--ccaanndd--sseett--bboouunndd If the number of candidates in the set is smaller than this value, always try to remove unnecessary ivs from the set when adding a new one. aavvgg--lloooopp--nniitteerr Average number of iterations of a loop. ddssee--mmaaxx--oobbjjeecctt--ssiizzee Maximum size (in bytes) of objects tracked bytewise by dead store elimination. Larger values may result in larger compila- tion times. ddssee--mmaaxx--aalliiaass--qquueerriieess--ppeerr--ssttoorree Maximum number of queries into the alias oracle per store. Larger values result in larger compilation times and may result in more removed dead stores. sscceevv--mmaaxx--eexxpprr--ssiizzee Bound on size of expressions used in the scalar evolutions ana- lyzer. Large expressions slow the analyzer. sscceevv--mmaaxx--eexxpprr--ccoommpplleexxiittyy Bound on the complexity of the expressions in the scalar evolu- tions analyzer. Complex expressions slow the analyzer. mmaaxx--ttrreeee--iiff--ccoonnvveerrssiioonn--pphhii--aarrggss Maximum number of arguments in a PHI supported by TREE if con- version unless the loop is marked with simd pragma. vveecctt--mmaaxx--vveerrssiioonn--ffoorr--aalliiggnnmmeenntt--cchheecckkss The maximum number of run-time checks that can be performed when doing loop versioning for alignment in the vectorizer. vveecctt--mmaaxx--vveerrssiioonn--ffoorr--aalliiaass--cchheecckkss The maximum number of run-time checks that can be performed when doing loop versioning for alias in the vectorizer. vveecctt--mmaaxx--ppeeeelliinngg--ffoorr--aalliiggnnmmeenntt The maximum number of loop peels to enhance access alignment for vectorizer. Value -1 means no limit. mmaaxx--iitteerraattiioonnss--ttoo--ttrraacckk The maximum number of iterations of a loop the brute-force al- gorithm for analysis of the number of iterations of the loop tries to evaluate. hhoott--bbbb--ccoouunntt--ffrraaccttiioonn The denominator n of fraction 1/n of the maximal execution count of a basic block in the entire program that a basic block needs to at least have in order to be considered hot. The de- fault is 10000, which means that a basic block is considered hot if its execution count is greater than 1/10000 of the maxi- mal execution count. 0 means that it is never considered hot. Used in non-LTO mode. hhoott--bbbb--ccoouunntt--wwss--ppeerrmmiillllee The number of most executed permilles, ranging from 0 to 1000, of the profiled execution of the entire program to which the execution count of a basic block must be part of in order to be considered hot. The default is 990, which means that a basic block is considered hot if its execution count contributes to the upper 990 permilles, or 99.0%, of the profiled execution of the entire program. 0 means that it is never considered hot. Used in LTO mode. hhoott--bbbb--ffrreeqquueennccyy--ffrraaccttiioonn The denominator n of fraction 1/n of the execution frequency of the entry block of a function that a basic block of this func- tion needs to at least have in order to be considered hot. The default is 1000, which means that a basic block is considered hot in a function if it is executed more frequently than 1/1000 of the frequency of the entry block of the function. 0 means that it is never considered hot. uunnlliikkeellyy--bbbb--ccoouunntt--ffrraaccttiioonn The denominator n of fraction 1/n of the number of profiled runs of the entire program below which the execution count of a basic block must be in order for the basic block to be consid- ered unlikely executed. The default is 20, which means that a basic block is considered unlikely executed if it is executed in fewer than 1/20, or 5%, of the runs of the program. 0 means that it is always considered unlikely executed. mmaaxx--pprreeddiicctteedd--iitteerraattiioonnss The maximum number of loop iterations we predict statically. This is useful in cases where a function contains a single loop with known bound and another loop with unknown bound. The known number of iterations is predicted correctly, while the unknown number of iterations average to roughly 10. This means that the loop without bounds appears artificially cold relative to the other one. bbuuiillttiinn--eexxppeecctt--pprroobbaabbiilliittyy Control the probability of the expression having the specified value. This parameter takes a percentage (i.e. 0 ... 100) as input. bbuuiillttiinn--ssttrriinngg--ccmmpp--iinnlliinnee--lleennggtthh The maximum length of a constant string for a builtin string cmp call eligible for inlining. aalliiggnn--tthhrreesshhoolldd Select fraction of the maximal frequency of executions of a ba- sic block in a function to align the basic block. aalliiggnn--lloooopp--iitteerraattiioonnss A loop expected to iterate at least the selected number of it- erations is aligned. ttrraacceerr--ddyynnaammiicc--ccoovveerraaggee ttrraacceerr--ddyynnaammiicc--ccoovveerraaggee--ffeeeeddbbaacckk This value is used to limit superblock formation once the given percentage of executed instructions is covered. This limits unnecessary code size expansion. The ttrraacceerr--ddyynnaammiicc--ccoovveerraaggee--ffeeeeddbbaacckk parameter is used only when profile feedback is available. The real profiles (as op- posed to statically estimated ones) are much less balanced al- lowing the threshold to be larger value. ttrraacceerr--mmaaxx--ccooddee--ggrroowwtthh Stop tail duplication once code growth has reached given per- centage. This is a rather artificial limit, as most of the du- plicates are eliminated later in cross jumping, so it may be set to much higher values than is the desired code growth. ttrraacceerr--mmiinn--bbrraanncchh--rraattiioo Stop reverse growth when the reverse probability of best edge is less than this threshold (in percent). ttrraacceerr--mmiinn--bbrraanncchh--pprroobbaabbiilliittyy ttrraacceerr--mmiinn--bbrraanncchh--pprroobbaabbiilliittyy--ffeeeeddbbaacckk Stop forward growth if the best edge has probability lower than this threshold. Similarly to ttrraacceerr--ddyynnaammiicc--ccoovveerraaggee two parameters are pro- vided. ttrraacceerr--mmiinn--bbrraanncchh--pprroobbaabbiilliittyy--ffeeeeddbbaacckk is used for com- pilation with profile feedback and ttrraacceerr--mmiinn--bbrraanncchh--pprroobbaabbiill-- iittyy compilation without. The value for compilation with pro- file feedback needs to be more conservative (higher) in order to make tracer effective. ssttaacckk--ccllaasshh--pprrootteeccttiioonn--gguuaarrdd--ssiizzee Specify the size of the operating system provided stack guard as 2 raised to _n_u_m bytes. Higher values may reduce the number of explicit probes, but a value larger than the operating sys- tem provided guard will leave code vulnerable to stack clash style attacks. ssttaacckk--ccllaasshh--pprrootteeccttiioonn--pprroobbee--iinntteerrvvaall Stack clash protection involves probing stack space as it is allocated. This param controls the maximum distance between probes into the stack as 2 raised to _n_u_m bytes. Higher values may reduce the number of explicit probes, but a value larger than the operating system provided guard will leave code vul- nerable to stack clash style attacks. mmaaxx--ccssee--ppaatthh--lleennggtthh The maximum number of basic blocks on path that CSE considers. mmaaxx--ccssee--iinnssnnss The maximum number of instructions CSE processes before flush- ing. ggggcc--mmiinn--eexxppaanndd GCC uses a garbage collector to manage its own memory alloca- tion. This parameter specifies the minimum percentage by which the garbage collector's heap should be allowed to expand be- tween collections. Tuning this may improve compilation speed; it has no effect on code generation. The default is 30% + 70% * (RAM/1GB) with an upper bound of 100% when RAM >= 1GB. If "getrlimit" is available, the notion of "RAM" is the smallest of actual RAM and "RLIMIT_DATA" or "RLIMIT_AS". If GCC is not able to calculate RAM on a particu- lar platform, the lower bound of 30% is used. Setting this pa- rameter and ggggcc--mmiinn--hheeaappssiizzee to zero causes a full collection to occur at every opportunity. This is extremely slow, but can be useful for debugging. ggggcc--mmiinn--hheeaappssiizzee Minimum size of the garbage collector's heap before it begins bothering to collect garbage. The first collection occurs af- ter the heap expands by ggggcc--mmiinn--eexxppaanndd% beyond ggggcc--mmiinn--hheeaapp-- ssiizzee. Again, tuning this may improve compilation speed, and has no effect on code generation. The default is the smaller of RAM/8, RLIMIT_RSS, or a limit that tries to ensure that RLIMIT_DATA or RLIMIT_AS are not ex- ceeded, but with a lower bound of 4096 (four megabytes) and an upper bound of 131072 (128 megabytes). If GCC is not able to calculate RAM on a particular platform, the lower bound is used. Setting this parameter very large effectively disables garbage collection. Setting this parameter and ggggcc--mmiinn--eexxppaanndd to zero causes a full collection to occur at every opportunity. mmaaxx--rreellooaadd--sseeaarrcchh--iinnssnnss The maximum number of instruction reload should look backward for equivalent register. Increasing values mean more aggres- sive optimization, making the compilation time increase with probably slightly better performance. mmaaxx--ccsseelliibb--mmeemmoorryy--llooccaattiioonnss The maximum number of memory locations cselib should take into account. Increasing values mean more aggressive optimization, making the compilation time increase with probably slightly better performance. mmaaxx--sscchheedd--rreeaaddyy--iinnssnnss The maximum number of instructions ready to be issued the scheduler should consider at any given time during the first scheduling pass. Increasing values mean more thorough searches, making the compilation time increase with probably little benefit. mmaaxx--sscchheedd--rreeggiioonn--bblloocckkss The maximum number of blocks in a region to be considered for interblock scheduling. mmaaxx--ppiippeelliinnee--rreeggiioonn--bblloocckkss The maximum number of blocks in a region to be considered for pipelining in the selective scheduler. mmaaxx--sscchheedd--rreeggiioonn--iinnssnnss The maximum number of insns in a region to be considered for interblock scheduling. mmaaxx--ppiippeelliinnee--rreeggiioonn--iinnssnnss The maximum number of insns in a region to be considered for pipelining in the selective scheduler. mmiinn--ssppeecc--pprroobb The minimum probability (in percents) of reaching a source block for interblock speculative scheduling. mmaaxx--sscchheedd--eexxtteenndd--rreeggiioonnss--iitteerrss The maximum number of iterations through CFG to extend regions. A value of 0 disables region extensions. mmaaxx--sscchheedd--iinnssnn--ccoonnfflliicctt--ddeellaayy The maximum conflict delay for an insn to be considered for speculative motion. sscchheedd--ssppeecc--pprroobb--ccuuttooffff The minimal probability of speculation success (in percents), so that speculative insns are scheduled. sscchheedd--ssttaattee--eeddggee--pprroobb--ccuuttooffff The minimum probability an edge must have for the scheduler to save its state across it. sscchheedd--mmeemm--ttrruuee--ddeepp--ccoosstt Minimal distance (in CPU cycles) between store and load target- ing same memory locations. sseellsscchheedd--mmaaxx--llooookkaahheeaadd The maximum size of the lookahead window of selective schedul- ing. It is a depth of search for available instructions. sseellsscchheedd--mmaaxx--sscchheedd--ttiimmeess The maximum number of times that an instruction is scheduled during selective scheduling. This is the limit on the number of iterations through which the instruction may be pipelined. sseellsscchheedd--iinnssnnss--ttoo--rreennaammee The maximum number of best instructions in the ready list that are considered for renaming in the selective scheduler. ssmmss--mmiinn--sscc The minimum value of stage count that swing modulo scheduler generates. mmaaxx--llaasstt--vvaalluuee--rrttll The maximum size measured as number of RTLs that can be recorded in an expression in combiner for a pseudo register as last known value of that register. mmaaxx--ccoommbbiinnee--iinnssnnss The maximum number of instructions the RTL combiner tries to combine. iinntteeggeerr--sshhaarree--lliimmiitt Small integer constants can use a shared data structure, reduc- ing the compiler's memory usage and increasing its speed. This sets the maximum value of a shared integer constant. sssspp--bbuuffffeerr--ssiizzee The minimum size of buffers (i.e. arrays) that receive stack smashing protection when --ffssttaacckk--pprrootteeccttoorr is used. mmiinn--ssiizzee--ffoorr--ssttaacckk--sshhaarriinngg The minimum size of variables taking part in stack slot sharing when not optimizing. mmaaxx--jjuummpp--tthhrreeaadd--dduupplliiccaattiioonn--ssttmmttss Maximum number of statements allowed in a block that needs to be duplicated when threading jumps. mmaaxx--ffiieellddss--ffoorr--ffiieelldd--sseennssiittiivvee Maximum number of fields in a structure treated in a field sen- sitive manner during pointer analysis. pprreeffeettcchh--llaatteennccyy Estimate on average number of instructions that are executed before prefetch finishes. The distance prefetched ahead is proportional to this constant. Increasing this number may also lead to less streams being prefetched (see ssiimmuullttaanneeoouuss-- pprreeffeettcchheess). ssiimmuullttaanneeoouuss--pprreeffeettcchheess Maximum number of prefetches that can run at the same time. ll11--ccaacchhee--lliinnee--ssiizzee The size of cache line in L1 data cache, in bytes. ll11--ccaacchhee--ssiizzee The size of L1 data cache, in kilobytes. ll22--ccaacchhee--ssiizzee The size of L2 data cache, in kilobytes. pprreeffeettcchh--ddyynnaammiicc--ssttrriiddeess Whether the loop array prefetch pass should issue software prefetch hints for strides that are non-constant. In some cases this may be beneficial, though the fact the stride is non-constant may make it hard to predict when there is clear benefit to issuing these hints. Set to 1 if the prefetch hints should be issued for non-con- stant strides. Set to 0 if prefetch hints should be issued only for strides that are known to be constant and below pprreeffeettcchh--mmiinniimmuumm--ssttrriiddee. pprreeffeettcchh--mmiinniimmuumm--ssttrriiddee Minimum constant stride, in bytes, to start using prefetch hints for. If the stride is less than this threshold, prefetch hints will not be issued. This setting is useful for processors that have hardware prefetchers, in which case there may be conflicts between the hardware prefetchers and the software prefetchers. If the hardware prefetchers have a maximum stride they can handle, it should be used here to improve the use of software prefetchers. A value of -1 means we don't have a threshold and therefore prefetch hints can be issued for any constant stride. This setting is only useful for strides that are known and con- stant. ddeessttrruuccttiivvee--iinntteerrffeerreennccee--ssiizzee ccoonnssttrruuccttiivvee--iinntteerrffeerreennccee--ssiizzee The values for the C++17 variables "std::hardware_destruc- tive_interference_size" and "std::hardware_constructive_inter- ference_size". The destructive interference size is the mini- mum recommended offset between two independent concurrently-ac- cessed objects; the constructive interference size is the maxi- mum recommended size of contiguous memory accessed together. Typically both will be the size of an L1 cache line for the target, in bytes. For a generic target covering a range of L1 cache line sizes, typically the constructive interference size will be the small end of the range and the destructive size will be the large end. The destructive interference size is intended to be used for layout, and thus has ABI impact. The default value is not ex- pected to be stable, and on some targets varies with --mmttuunnee, so use of this variable in a context where ABI stability is impor- tant, such as the public interface of a library, is strongly discouraged; if it is used in that context, users can stabilize the value using this option. The constructive interference size is less sensitive, as it is typically only used in a ssttaattiicc__aasssseerrtt to make sure that a type fits within a cache line. See also --WWiinntteerrffeerreennccee--ssiizzee. lloooopp--iinntteerrcchhaannggee--mmaaxx--nnuumm--ssttmmttss The maximum number of stmts in a loop to be interchanged. lloooopp--iinntteerrcchhaannggee--ssttrriiddee--rraattiioo The minimum ratio between stride of two loops for interchange to be profitable. mmiinn--iinnssnn--ttoo--pprreeffeettcchh--rraattiioo The minimum ratio between the number of instructions and the number of prefetches to enable prefetching in a loop. pprreeffeettcchh--mmiinn--iinnssnn--ttoo--mmeemm--rraattiioo The minimum ratio between the number of instructions and the number of memory references to enable prefetching in a loop. uussee--ccaannoonniiccaall--ttyyppeess Whether the compiler should use the "canonical" type system. Should always be 1, which uses a more efficient internal mecha- nism for comparing types in C++ and Objective-C++. However, if bugs in the canonical type system are causing compilation fail- ures, set this value to 0 to disable canonical types. sswwiittcchh--ccoonnvveerrssiioonn--mmaaxx--bbrraanncchh--rraattiioo Switch initialization conversion refuses to create arrays that are bigger than sswwiittcchh--ccoonnvveerrssiioonn--mmaaxx--bbrraanncchh--rraattiioo times the number of branches in the switch. mmaaxx--ppaarrttiiaall--aannttiicc--lleennggtthh Maximum length of the partial antic set computed during the tree partial redundancy elimination optimization (--ffttrreeee--pprree) when optimizing at --OO33 and above. For some sorts of source code the enhanced partial redundancy elimination optimization can run away, consuming all of the memory available on the host machine. This parameter sets a limit on the length of the sets that are computed, which prevents the runaway behavior. Set- ting a value of 0 for this parameter allows an unlimited set length. rrppoo--vvnn--mmaaxx--lloooopp--ddeepptthh Maximum loop depth that is value-numbered optimistically. When the limit hits the innermost _r_p_o_-_v_n_-_m_a_x_-_l_o_o_p_-_d_e_p_t_h loops and the outermost loop in the loop nest are value-numbered opti- mistically and the remaining ones not. ssccccvvnn--mmaaxx--aalliiaass--qquueerriieess--ppeerr--aacccceessss Maximum number of alias-oracle queries we perform when looking for redundancies for loads and stores. If this limit is hit the search is aborted and the load or store is not considered redundant. The number of queries is algorithmically limited to the number of stores on all paths from the load to the function entry. iirraa--mmaaxx--llooooppss--nnuumm IRA uses regional register allocation by default. If a func- tion contains more loops than the number given by this parame- ter, only at most the given number of the most frequently-exe- cuted loops form regions for regional register allocation. iirraa--mmaaxx--ccoonnfflliicctt--ttaabbllee--ssiizzee Although IRA uses a sophisticated algorithm to compress the conflict table, the table can still require excessive amounts of memory for huge functions. If the conflict table for a function could be more than the size in MB given by this param- eter, the register allocator instead uses a faster, simpler, and lower-quality algorithm that does not require building a pseudo-register conflict table. iirraa--lloooopp--rreesseerrvveedd--rreeggss IRA can be used to evaluate more accurate register pressure in loops for decisions to move loop invariants (see --OO33). The number of available registers reserved for some other purposes is given by this parameter. Default of the parameter is the best found from numerous experiments. iirraa--ccoonnssiiddeerr--dduupp--iinn--aallll--aallttss Make IRA to consider matching constraint (duplicated operand number) heavily in all available alternatives for preferred register class. If it is set as zero, it means IRA only re- spects the matching constraint when it's in the only available alternative with an appropriate register class. Otherwise, it means IRA will check all available alternatives for preferred register class even if it has found some choice with an appro- priate register class and respect the found qualified matching constraint. llrraa--iinnhheerriittaannccee--eebbbb--pprroobbaabbiilliittyy--ccuuttooffff LRA tries to reuse values reloaded in registers in subsequent insns. This optimization is called inheritance. EBB is used as a region to do this optimization. The parameter defines a minimal fall-through edge probability in percentage used to add BB to inheritance EBB in LRA. The default value was chosen from numerous runs of SPEC2000 on x86-64. lloooopp--iinnvvaarriiaanntt--mmaaxx--bbbbss--iinn--lloooopp Loop invariant motion can be very expensive, both in compila- tion time and in amount of needed compile-time memory, with very large loops. Loops with more basic blocks than this pa- rameter won't have loop invariant motion optimization performed on them. lloooopp--mmaaxx--ddaattaarreeffss--ffoorr--ddaattaaddeeppss Building data dependencies is expensive for very large loops. This parameter limits the number of data references in loops that are considered for data dependence analysis. These large loops are no handled by the optimizations using loop data de- pendencies. mmaaxx--vvaarrttrraacckk--ssiizzee Sets a maximum number of hash table slots to use during vari- able tracking dataflow analysis of any function. If this limit is exceeded with variable tracking at assignments enabled, analysis for that function is retried without it, after remov- ing all debug insns from the function. If the limit is ex- ceeded even without debug insns, var tracking analysis is com- pletely disabled for the function. Setting the parameter to zero makes it unlimited. mmaaxx--vvaarrttrraacckk--eexxpprr--ddeepptthh Sets a maximum number of recursion levels when attempting to map variable names or debug temporaries to value expressions. This trades compilation time for more complete debug informa- tion. If this is set too low, value expressions that are available and could be represented in debug information may end up not being used; setting this higher may enable the compiler to find more complex debug expressions, but compile time and memory use may grow. mmaaxx--ddeebbuugg--mmaarrkkeerr--ccoouunntt Sets a threshold on the number of debug markers (e.g. begin stmt markers) to avoid complexity explosion at inlining or ex- panding to RTL. If a function has more such gimple stmts than the set limit, such stmts will be dropped from the inlined copy of a function, and from its RTL expansion. mmiinn--nnoonnddeebbuugg--iinnssnn--uuiidd Use uids starting at this parameter for nondebug insns. The range below the parameter is reserved exclusively for debug in- sns created by --ffvvaarr--ttrraacckkiinngg--aassssiiggnnmmeennttss, but debug insns may get (non-overlapping) uids above it if the reserved range is exhausted. iippaa--ssrraa--ppttrr--ggrroowwtthh--ffaaccttoorr IPA-SRA replaces a pointer to an aggregate with one or more new parameters only when their cumulative size is less or equal to iippaa--ssrraa--ppttrr--ggrroowwtthh--ffaaccttoorr times the size of the original pointer parameter. iippaa--ssrraa--mmaaxx--rreeppllaacceemmeennttss Maximum pieces of an aggregate that IPA-SRA tracks. As a con- sequence, it is also the maximum number of replacements of a formal parameter. ssrraa--mmaaxx--ssccaallaarriizzaattiioonn--ssiizzee--OOssppeeeedd ssrraa--mmaaxx--ssccaallaarriizzaattiioonn--ssiizzee--OOssiizzee The two Scalar Reduction of Aggregates passes (SRA and IPA-SRA) aim to replace scalar parts of aggregates with uses of indepen- dent scalar variables. These parameters control the maximum size, in storage units, of aggregate which is considered for replacement when compiling for speed (ssrraa--mmaaxx--ssccaallaarriizzaattiioonn-- ssiizzee--OOssppeeeedd) or size (ssrraa--mmaaxx--ssccaallaarriizzaattiioonn--ssiizzee--OOssiizzee) respec- tively. ssrraa--mmaaxx--pprrooppaaggaattiioonnss The maximum number of artificial accesses that Scalar Replace- ment of Aggregates (SRA) will track, per one local variable, in order to facilitate copy propagation. ttmm--mmaaxx--aaggggrreeggaattee--ssiizzee When making copies of thread-local variables in a transaction, this parameter specifies the size in bytes after which vari- ables are saved with the logging functions as opposed to save/restore code sequence pairs. This option only applies when using --ffggnnuu--ttmm. ggrraapphhiittee--mmaaxx--nnbb--ssccoopp--ppaarraammss To avoid exponential effects in the Graphite loop transforms, the number of parameters in a Static Control Part (SCoP) is bounded. A value of zero can be used to lift the bound. A variable whose value is unknown at compilation time and defined outside a SCoP is a parameter of the SCoP. lloooopp--bblloocckk--ttiillee--ssiizzee Loop blocking or strip mining transforms, enabled with --fflloooopp--bblloocckk or --fflloooopp--ssttrriipp--mmiinnee, strip mine each loop in the loop nest by a given number of iterations. The strip length can be changed using the lloooopp--bblloocckk--ttiillee--ssiizzee parameter. iippaa--jjuummpp--ffuunnccttiioonn--llooookkuuppss Specifies number of statements visited during jump function offset discovery. iippaa--ccpp--vvaalluuee--lliisstt--ssiizzee IPA-CP attempts to track all possible values and types passed to a function's parameter in order to propagate them and per- form devirtualization. iippaa--ccpp--vvaalluuee--lliisstt--ssiizzee is the maximum number of values and types it stores per one formal parameter of a function. iippaa--ccpp--eevvaall--tthhrreesshhoolldd IPA-CP calculates its own score of cloning profitability heuristics and performs those cloning opportunities with scores that exceed iippaa--ccpp--eevvaall--tthhrreesshhoolldd. iippaa--ccpp--mmaaxx--rreeccuurrssiivvee--ddeepptthh Maximum depth of recursive cloning for self-recursive function. iippaa--ccpp--mmiinn--rreeccuurrssiivvee--pprroobbaabbiilliittyy Recursive cloning only when the probability of call being exe- cuted exceeds the parameter. iippaa--ccpp--pprrooffiillee--ccoouunntt--bbaassee When using --ffpprrooffiillee--uussee option, IPA-CP will consider the mea- sured execution count of a call graph edge at this percentage position in their histogram as the basis for its heuristics calculation. iippaa--ccpp--rreeccuurrssiivvee--ffrreeqq--ffaaccttoorr The number of times interprocedural copy propagation expects recursive functions to call themselves. iippaa--ccpp--rreeccuurrssiioonn--ppeennaallttyy Percentage penalty the recursive functions will receive when they are evaluated for cloning. iippaa--ccpp--ssiinnggllee--ccaallll--ppeennaallttyy Percentage penalty functions containing a single call to an- other function will receive when they are evaluated for cloning. iippaa--mmaaxx--aagggg--iitteemmss IPA-CP is also capable to propagate a number of scalar values passed in an aggregate. iippaa--mmaaxx--aagggg--iitteemmss controls the maximum number of such values per one parameter. iippaa--ccpp--lloooopp--hhiinntt--bboonnuuss When IPA-CP determines that a cloning candidate would make the number of iterations of a loop known, it adds a bonus of iippaa-- ccpp--lloooopp--hhiinntt--bboonnuuss to the profitability score of the candidate. iippaa--mmaaxx--lloooopp--pprreeddiiccaatteess The maximum number of different predicates IPA will use to de- scribe when loops in a function have known properties. iippaa--mmaaxx--aaaa--sstteeppss During its analysis of function bodies, IPA-CP employs alias analysis in order to track values pointed to by function param- eters. In order not spend too much time analyzing huge func- tions, it gives up and consider all memory clobbered after ex- amining iippaa--mmaaxx--aaaa--sstteeppss statements modifying memory. iippaa--mmaaxx--sswwiittcchh--pprreeddiiccaattee--bboouunnddss Maximal number of boundary endpoints of case ranges of switch statement. For switch exceeding this limit, IPA-CP will not construct cloning cost predicate, which is used to estimate cloning benefit, for default case of the switch statement. iippaa--mmaaxx--ppaarraamm--eexxpprr--ooppss IPA-CP will analyze conditional statement that references some function parameter to estimate benefit for cloning upon certain constant value. But if number of operations in a parameter ex- pression exceeds iippaa--mmaaxx--ppaarraamm--eexxpprr--ooppss, the expression is treated as complicated one, and is not handled by IPA analysis. llttoo--ppaarrttiittiioonnss Specify desired number of partitions produced during WHOPR com- pilation. The number of partitions should exceed the number of CPUs used for compilation. llttoo--mmiinn--ppaarrttiittiioonn Size of minimal partition for WHOPR (in estimated instruc- tions). This prevents expenses of splitting very small pro- grams into too many partitions. llttoo--mmaaxx--ppaarrttiittiioonn Size of max partition for WHOPR (in estimated instructions). to provide an upper bound for individual size of partition. Meant to be used only with balanced partitioning. llttoo--mmaaxx--ssttrreeaammiinngg--ppaarraalllleelliissmm Maximal number of parallel processes used for LTO streaming. ccxxxx--mmaaxx--nnaammeessppaacceess--ffoorr--ddiiaaggnnoossttiicc--hheellpp The maximum number of namespaces to consult for suggestions when C++ name lookup fails for an identifier. ssiinnkk--ffrreeqquueennccyy--tthhrreesshhoolldd The maximum relative execution frequency (in percents) of the target block relative to a statement's original block to allow statement sinking of a statement. Larger numbers result in more aggressive statement sinking. A small positive adjustment is applied for statements with memory operands as those are even more profitable so sink. mmaaxx--ssttoorreess--ttoo--ssiinnkk The maximum number of conditional store pairs that can be sunk. Set to 0 if either vectorization (--ffttrreeee--vveeccttoorriizzee) or if-con- version (--ffttrreeee--lloooopp--iiff--ccoonnvveerrtt) is disabled. ccaassee--vvaalluueess--tthhrreesshhoolldd The smallest number of different values for which it is best to use a jump-table instead of a tree of conditional branches. If the value is 0, use the default for the machine. jjuummpp--ttaabbllee--mmaaxx--ggrroowwtthh--rraattiioo--ffoorr--ssiizzee The maximum code size growth ratio when expanding into a jump table (in percent). The parameter is used when optimizing for size. jjuummpp--ttaabbllee--mmaaxx--ggrroowwtthh--rraattiioo--ffoorr--ssppeeeedd The maximum code size growth ratio when expanding into a jump table (in percent). The parameter is used when optimizing for speed. ttrreeee--rreeaassssoocc--wwiiddtthh Set the maximum number of instructions executed in parallel in reassociated tree. This parameter overrides target dependent heuristics used by default if has non zero value. sscchheedd--pprreessssuurree--aallggoorriitthhmm Choose between the two available implementations of --ffsscchheedd--pprreessssuurree. Algorithm 1 is the original implementation and is the more likely to prevent instructions from being re- ordered. Algorithm 2 was designed to be a compromise between the relatively conservative approach taken by algorithm 1 and the rather aggressive approach taken by the default scheduler. It relies more heavily on having a regular register file and accurate register pressure classes. See _h_a_i_f_a_-_s_c_h_e_d_._c_c in the GCC sources for more details. The default choice depends on the target. mmaaxx--ssllssrr--ccaanndd--ssccaann Set the maximum number of existing candidates that are consid- ered when seeking a basis for a new straight-line strength re- duction candidate. aassaann--gglloobbaallss Enable buffer overflow detection for global objects. This kind of protection is enabled by default if you are using --ffssaannii-- ttiizzee==aaddddrreessss option. To disable global objects protection use ----ppaarraamm aassaann--gglloobbaallss==00. aassaann--ssttaacckk Enable buffer overflow detection for stack objects. This kind of protection is enabled by default when using --ffssaanniittiizzee==aadd-- ddrreessss. To disable stack protection use ----ppaarraamm aassaann--ssttaacckk==00 option. aassaann--iinnssttrruummeenntt--rreeaaddss Enable buffer overflow detection for memory reads. This kind of protection is enabled by default when using --ffssaanniittiizzee==aadd-- ddrreessss. To disable memory reads protection use ----ppaarraamm aassaann--iinn-- ssttrruummeenntt--rreeaaddss==00. aassaann--iinnssttrruummeenntt--wwrriitteess Enable buffer overflow detection for memory writes. This kind of protection is enabled by default when using --ffssaanniittiizzee==aadd-- ddrreessss. To disable memory writes protection use ----ppaarraamm aassaann--iinnssttrruummeenntt--wwrriitteess==00 option. aassaann--mmeemmiinnttrriinn Enable detection for built-in functions. This kind of protec- tion is enabled by default when using --ffssaanniittiizzee==aaddddrreessss. To disable built-in functions protection use ----ppaarraamm aassaann--mmeemm-- iinnttrriinn==00. aassaann--uussee--aafftteerr--rreettuurrnn Enable detection of use-after-return. This kind of protection is enabled by default when using the --ffssaanniittiizzee==aaddddrreessss option. To disable it use ----ppaarraamm aassaann--uussee--aafftteerr--rreettuurrnn==00. Note: By default the check is disabled at run time. To enable it, add "detect_stack_use_after_return=1" to the environment variable AASSAANN__OOPPTTIIOONNSS. aassaann--iinnssttrruummeennttaattiioonn--wwiitthh--ccaallll--tthhrreesshhoolldd If number of memory accesses in function being instrumented is greater or equal to this number, use callbacks instead of in- line checks. E.g. to disable inline code use ----ppaarraamm aassaann--iinn-- ssttrruummeennttaattiioonn--wwiitthh--ccaallll--tthhrreesshhoolldd==00. hhwwaassaann--iinnssttrruummeenntt--ssttaacckk Enable hwasan instrumentation of statically sized stack-allo- cated variables. This kind of instrumentation is enabled by default when using --ffssaanniittiizzee==hhwwaaddddrreessss and disabled by default when using --ffssaanniittiizzee==kkeerrnneell--hhwwaaddddrreessss. To disable stack in- strumentation use ----ppaarraamm hhwwaassaann--iinnssttrruummeenntt--ssttaacckk==00, and to en- able it use ----ppaarraamm hhwwaassaann--iinnssttrruummeenntt--ssttaacckk==11. hhwwaassaann--rraannddoomm--ffrraammee--ttaagg When using stack instrumentation, decide tags for stack vari- ables using a deterministic sequence beginning at a random tag for each frame. With this parameter unset tags are chosen us- ing the same sequence but beginning from 1. This is enabled by default for --ffssaanniittiizzee==hhwwaaddddrreessss and unavailable for --ffssaannii-- ttiizzee==kkeerrnneell--hhwwaaddddrreessss. To disable it use ----ppaarraamm hhwwaassaann--rraann-- ddoomm--ffrraammee--ttaagg==00. hhwwaassaann--iinnssttrruummeenntt--aallllooccaass Enable hwasan instrumentation of dynamically sized stack-allo- cated variables. This kind of instrumentation is enabled by default when using --ffssaanniittiizzee==hhwwaaddddrreessss and disabled by default when using --ffssaanniittiizzee==kkeerrnneell--hhwwaaddddrreessss. To disable instrumen- tation of such variables use ----ppaarraamm hhwwaassaann--iinnssttrruummeenntt--aalllloo-- ccaass==00, and to enable it use ----ppaarraamm hhwwaassaann--iinnssttrruummeenntt--aalllloo-- ccaass==11. hhwwaassaann--iinnssttrruummeenntt--rreeaaddss Enable hwasan checks on memory reads. Instrumentation of reads is enabled by default for both --ffssaanniittiizzee==hhwwaaddddrreessss and --ffssaannii-- ttiizzee==kkeerrnneell--hhwwaaddddrreessss. To disable checking memory reads use ----ppaarraamm hhwwaassaann--iinnssttrruummeenntt--rreeaaddss==00. hhwwaassaann--iinnssttrruummeenntt--wwrriitteess Enable hwasan checks on memory writes. Instrumentation of writes is enabled by default for both --ffssaanniittiizzee==hhwwaaddddrreessss and --ffssaanniittiizzee==kkeerrnneell--hhwwaaddddrreessss. To disable checking memory writes use ----ppaarraamm hhwwaassaann--iinnssttrruummeenntt--wwrriitteess==00. hhwwaassaann--iinnssttrruummeenntt--mmeemm--iinnttrriinnssiiccss Enable hwasan instrumentation of builtin functions. Instrumen- tation of these builtin functions is enabled by default for both --ffssaanniittiizzee==hhwwaaddddrreessss and --ffssaanniittiizzee==kkeerrnneell--hhwwaaddddrreessss. To disable instrumentation of builtin functions use ----ppaarraamm hhwwaassaann--iinnssttrruummeenntt--mmeemm--iinnttrriinnssiiccss==00. uussee--aafftteerr--ssccooppee--ddiirreecctt--eemmiissssiioonn--tthhrreesshhoolldd If the size of a local variable in bytes is smaller or equal to this number, directly poison (or unpoison) shadow memory in- stead of using run-time callbacks. ttssaann--ddiissttiinngguuiisshh--vvoollaattiillee Emit special instrumentation for accesses to volatiles. ttssaann--iinnssttrruummeenntt--ffuunncc--eennttrryy--eexxiitt Emit instrumentation calls to ____t_s_a_n___f_u_n_c___e_n_t_r_y_(_) and ____t_s_a_n___f_u_n_c___e_x_i_t_(_). mmaaxx--ffssmm--tthhrreeaadd--ppaatthh--iinnssnnss Maximum number of instructions to copy when duplicating blocks on a finite state automaton jump thread path. mmaaxx--ffssmm--tthhrreeaadd--lleennggtthh Maximum number of basic blocks on a jump thread path. tthhrreeaaddeerr--ddeebbuugg threader-debug=[none|all] Enables verbose dumping of the threader solver. ppaarrllooooppss--cchhuunnkk--ssiizzee Chunk size of omp schedule for loops parallelized by parloops. ppaarrllooooppss--sscchheedduullee Schedule type of omp schedule for loops parallelized by par- loops (static, dynamic, guided, auto, runtime). ppaarrllooooppss--mmiinn--ppeerr--tthhrreeaadd The minimum number of iterations per thread of an innermost parallelized loop for which the parallelized variant is pre- ferred over the single threaded one. Note that for a paral- lelized loop nest the minimum number of iterations of the out- ermost loop per thread is two. mmaaxx--ssssaa--nnaammee--qquueerryy--ddeepptthh Maximum depth of recursion when querying properties of SSA names in things like fold routines. One level of recursion corresponds to following a use-def chain. mmaaxx--ssppeeccuullaattiivvee--ddeevviirrtt--mmaayyddeeffss The maximum number of may-defs we analyze when looking for a must-def specifying the dynamic type of an object that invokes a virtual call we may be able to devirtualize speculatively. mmaaxx--vvrrpp--sswwiittcchh--aasssseerrttiioonnss The maximum number of assertions to add along the default edge of a switch statement during VRP. eevvrrpp--ssppaarrssee--tthhrreesshhoolldd Maximum number of basic blocks before EVRP uses a sparse cache. eevvrrpp--mmooddee Specifies the mode Early VRP should operate in. vvrrpp11--mmooddee Specifies the mode VRP pass 1 should operate in. vvrrpp22--mmooddee Specifies the mode VRP pass 2 should operate in. rraannggeerr--ddeebbuugg Specifies the type of debug output to be issued for ranges. eevvrrpp--sswwiittcchh--lliimmiitt Specifies the maximum number of switch cases before EVRP ig- nores a switch. uunnrroollll--jjaamm--mmiinn--ppeerrcceenntt The minimum percentage of memory references that must be opti- mized away for the unroll-and-jam transformation to be consid- ered profitable. uunnrroollll--jjaamm--mmaaxx--uunnrroollll The maximum number of times the outer loop should be unrolled by the unroll-and-jam transformation. mmaaxx--rrttll--iiff--ccoonnvveerrssiioonn--uunnpprreeddiiccttaabbllee--ccoosstt Maximum permissible cost for the sequence that would be gener- ated by the RTL if-conversion pass for a branch that is consid- ered unpredictable. mmaaxx--vvaarriiaabbllee--eexxppaannssiioonnss--iinn--uunnrroolllleerr If --ffvvaarriiaabbllee--eexxppaannssiioonn--iinn--uunnrroolllleerr is used, the maximum number of times that an individual variable will be expanded during loop unrolling. ppaarrttiiaall--iinnlliinniinngg--eennttrryy--pprroobbaabbiilliittyy Maximum probability of the entry BB of split region (in percent relative to entry BB of the function) to make partial inlining happen. mmaaxx--ttrraacckkeedd--ssttrrlleennss Maximum number of strings for which strlen optimization pass will track string lengths. ggccssee--aafftteerr--rreellooaadd--ppaarrttiiaall--ffrraaccttiioonn The threshold ratio for performing partial redundancy elimina- tion after reload. ggccssee--aafftteerr--rreellooaadd--ccrriittiiccaall--ffrraaccttiioonn The threshold ratio of critical edges execution count that per- mit performing redundancy elimination after reload. mmaaxx--lloooopp--hheeaaddeerr--iinnssnnss The maximum number of insns in loop header duplicated by the copy loop headers pass. vveecctt--eeppiilloogguueess--nnoommaasskk Enable loop epilogue vectorization using smaller vector size. vveecctt--ppaarrttiiaall--vveeccttoorr--uussaaggee Controls when the loop vectorizer considers using partial vec- tor loads and stores as an alternative to falling back to scalar code. 0 stops the vectorizer from ever using partial vector loads and stores. 1 allows partial vector loads and stores if vectorization removes the need for the code to iter- ate. 2 allows partial vector loads and stores in all loops. The parameter only has an effect on targets that support par- tial vector loads and stores. vveecctt--iinnnneerr--lloooopp--ccoosstt--ffaaccttoorr The maximum factor which the loop vectorizer applies to the cost of statements in an inner loop relative to the loop being vectorized. The factor applied is the maximum of the estimated number of iterations of the inner loop and this parameter. The default value of this parameter is 50. vveecctt--iinndduuccttiioonn--ffllooaatt Enable loop vectorization of floating point inductions. aavvooiidd--ffmmaa--mmaaxx--bbiittss Maximum number of bits for which we avoid creating FMAs. ssmmss--lloooopp--aavveerraaggee--ccoouunntt--tthhrreesshhoolldd A threshold on the average loop count considered by the swing modulo scheduler. ssmmss--ddffaa--hhiissttoorryy The number of cycles the swing modulo scheduler considers when checking conflicts using DFA. ggrraapphhiittee--aallllooww--ccooddeeggeenn--eerrrroorrss Whether codegen errors should be ICEs when --ffcchheecckkiinngg. ssmmss--mmaaxx--iiii--ffaaccttoorr A factor for tuning the upper bound that swing modulo scheduler uses for scheduling a loop. llrraa--mmaaxx--ccoonnssiiddeerreedd--rreellooaadd--ppsseeuuddooss The max number of reload pseudos which are considered during spilling a non-reload pseudo. mmaaxx--ppooww--ssqqrrtt--ddeepptthh Maximum depth of sqrt chains to use when synthesizing exponen- tiation by a real constant. mmaaxx--ddssee--aaccttiivvee--llooccaall--ssttoorreess Maximum number of active local stores in RTL dead store elimi- nation. aassaann--iinnssttrruummeenntt--aallllooccaass Enable asan allocas/VLAs protection. mmaaxx--iitteerraattiioonnss--ccoommppuuttaattiioonn--ccoosstt Bound on the cost of an expression to compute the number of it- erations. mmaaxx--iissll--ooppeerraattiioonnss Maximum number of isl operations, 0 means unlimited. ggrraapphhiittee--mmaaxx--aarrrraayyss--ppeerr--ssccoopp Maximum number of arrays per scop. mmaaxx--vvaarrttrraacckk--rreevveerrssee--oopp--ssiizzee Max. size of loc list for which reverse ops should be added. ffssmm--ssccaallee--ppaatthh--ssttmmttss Scale factor to apply to the number of statements in a thread- ing path when comparing to the number of (scaled) blocks. uunniinniitt--ccoonnttrrooll--ddeepp--aatttteemmppttss Maximum number of nested calls to search for control dependen- cies during uninitialized variable analysis. ffssmm--ssccaallee--ppaatthh--bblloocckkss Scale factor to apply to the number of blocks in a threading path when comparing to the number of (scaled) statements. sscchheedd--aauuttoopprreeff--qquueeuuee--ddeepptthh Hardware autoprefetcher scheduler model control flag. Number of lookahead cycles the model looks into; at ' ' only enable instruction sorting heuristic. lloooopp--vveerrssiioonniinngg--mmaaxx--iinnnneerr--iinnssnnss The maximum number of instructions that an inner loop can have before the loop versioning pass considers it too big to copy. lloooopp--vveerrssiioonniinngg--mmaaxx--oouutteerr--iinnssnnss The maximum number of instructions that an outer loop can have before the loop versioning pass considers it too big to copy, discounting any instructions in inner loops that directly bene- fit from versioning. ssssaa--nnaammee--ddeeff--cchhaaiinn--lliimmiitt The maximum number of SSA_NAME assignments to follow in deter- mining a property of a variable such as its value. This limits the number of iterations or recursive calls GCC performs when optimizing certain statements or when determining their valid- ity prior to issuing diagnostics. ssttoorree--mmeerrggiinngg--mmaaxx--ssiizzee Maximum size of a single store merging region in bytes. hhaasshh--ttaabbllee--vveerriiffiiccaattiioonn--lliimmiitt The number of elements for which hash table verification is done for each searched element. mmaaxx--ffiinndd--bbaassee--tteerrmm--vvaalluueess Maximum number of VALUEs handled during a single find_base_term call. aannaallyyzzeerr--mmaaxx--eennooddeess--ppeerr--pprrooggrraamm--ppooiinntt The maximum number of exploded nodes per program point within the analyzer, before terminating analysis of that point. aannaallyyzzeerr--mmaaxx--ccoonnssttrraaiinnttss The maximum number of constraints per state. aannaallyyzzeerr--mmiinn--ssnnooddeess--ffoorr--ccaallll--ssuummmmaarryy The minimum number of supernodes within a function for the ana- lyzer to consider summarizing its effects at call sites. aannaallyyzzeerr--mmaaxx--eennooddeess--ffoorr--ffuullll--dduummpp The maximum depth of exploded nodes that should appear in a dot dump before switching to a less verbose format. aannaallyyzzeerr--mmaaxx--rreeccuurrssiioonn--ddeepptthh The maximum number of times a callsite can appear in a call stack within the analyzer, before terminating analysis of a call that would recurse deeper. aannaallyyzzeerr--mmaaxx--ssvvaalluuee--ddeepptthh The maximum depth of a symbolic value, before approximating the value as unknown. aannaallyyzzeerr--mmaaxx--iinnffeeaassiibbllee--eeddggeess The maximum number of infeasible edges to reject before declar- ing a diagnostic as infeasible. ggiimmppllee--ffee--ccoommppuutteedd--hhoott--bbbb--tthhrreesshhoolldd The number of executions of a basic block which is considered hot. The parameter is used only in GIMPLE FE. aannaallyyzzeerr--bbbb--eexxpplloossiioonn--ffaaccttoorr The maximum number of 'after supernode' exploded nodes within the analyzer per supernode, before terminating analysis. rraannggeerr--llooggiiccaall--ddeepptthh Maximum depth of logical expression evaluation ranger will look through when evaluating outgoing edge ranges. rreellaattiioonn--bblloocckk--lliimmiitt Maximum number of relations the oracle will register in a basic block. mmiinn--ppaaggeessiizzee Minimum page size for warning purposes. ooppeennaacccc--kkeerrnneellss Specify mode of OpenACC `kernels' constructs handling. With ----ppaarraamm==ooppeennaacccc--kkeerrnneellss==ddeeccoommppoossee, OpenACC `kernels' constructs are decomposed into parts, a sequence of compute constructs, each then handled individually. This is work in progress. With ----ppaarraamm==ooppeennaacccc--kkeerrnneellss==ppaarrllooooppss, OpenACC `kernels' con- structs are handled by the ppaarrllooooppss pass, en bloc. This is the current default. ooppeennaacccc--pprriivvaattiizzaattiioonn Specify mode of OpenACC privatization diagnostics for --ffoopptt--iinnffoo--oommpp--nnoottee and applicable --ffdduummpp--ttrreeee--**--ddeettaaiillss. With ----ppaarraamm==ooppeennaacccc--pprriivvaattiizzaattiioonn==qquuiieett, don't diagnose. This is the current default. With ----ppaarraamm==ooppeennaacccc--pprriivvaattiizzaattiioonn==nnooiissyy, do diagnose. The following choices of _n_a_m_e are available on AArch64 targets: aaaarrcchh6644--ssvvee--ccoommppaarree--ccoossttss When vectorizing for SVE, consider using "unpacked" vectors for smaller elements and use the cost model to pick the cheapest approach. Also use the cost model to choose between SVE and Advanced SIMD vectorization. Using unpacked vectors includes storing smaller elements in larger containers and accessing elements with extending loads and truncating stores. aaaarrcchh6644--ffllooaatt--rreeccpp--pprreecciissiioonn The number of Newton iterations for calculating the reciprocal for float type. The precision of division is proportional to this param when division approximation is enabled. The default value is 1. aaaarrcchh6644--ddoouubbllee--rreeccpp--pprreecciissiioonn The number of Newton iterations for calculating the reciprocal for double type. The precision of division is propotional to this param when division approximation is enabled. The default value is 2. aaaarrcchh6644--aauuttoovveecc--pprreeffeerreennccee Force an ISA selection strategy for auto-vectorization. Ac- cepts values from 0 to 4, inclusive. 00 Use the default heuristics. 11 Use only Advanced SIMD for auto-vectorization. 22 Use only SVE for auto-vectorization. 33 Use both Advanced SIMD and SVE. Prefer Advanced SIMD when the costs are deemed equal. 44 Use both Advanced SIMD and SVE. Prefer SVE when the costs are deemed equal. The default value is 0. aaaarrcchh6644--lloooopp--vveecctt--iissssuuee--rraattee--nniitteerrss The tuning for some AArch64 CPUs tries to take both latencies and issue rates into account when deciding whether a loop should be vectorized using SVE, vectorized using Advanced SIMD, or not vectorized at all. If this parameter is set to _n, GCC will not use this heuristic for loops that are known to execute in fewer than _n Advanced SIMD iterations. aaaarrcchh6644--vveecctt--uunnrroollll--lliimmiitt The vectorizer will use available tuning information to deter- mine whether it would be beneficial to unroll the main vector- ized loop and by how much. This parameter set's the upper bound of how much the vectorizer will unroll the main loop. The default value is four. The following choices of _n_a_m_e are available on i386 and x86_64 tar- gets: xx8866--ssttllff--wwiinnddooww--nniinnssnnss Instructions number above which STFL stall penalty can be com- pensated. PPrrooggrraamm IInnssttrruummeennttaattiioonn OOppttiioonnss GCC supports a number of command-line options that control adding run- time instrumentation to the code it normally generates. For example, one purpose of instrumentation is collect profiling statistics for use in finding program hot spots, code coverage analysis, or profile-guided optimizations. Another class of program instrumentation is adding run- time checking to detect programming errors like invalid pointer deref- erences or out-of-bounds array accesses, as well as deliberately hos- tile attacks such as stack smashing or C++ vtable hijacking. There is also a general hook which can be used to implement other forms of trac- ing or function-level instrumentation for debug or program analysis purposes. --pp --ppgg Generate extra code to write profile information suitable for the analysis program pprrooff (for --pp) or ggpprrooff (for --ppgg). You must use this option when compiling the source files you want data about, and you must also use it when linking. You can use the function attribute "no_instrument_function" to sup- press profiling of individual functions when compiling with these options. --ffpprrooffiillee--aarrccss Add code so that program flow _a_r_c_s are instrumented. During execu- tion the program records how many times each branch and call is ex- ecuted and how many times it is taken or returns. On targets that support constructors with priority support, profiling properly han- dles constructors, destructors and C++ constructors (and destruc- tors) of classes which are used as a type of a global variable. When the compiled program exits it saves this data to a file called _a_u_x_n_a_m_e_._g_c_d_a for each source file. The data may be used for pro- file-directed optimizations (--ffbbrraanncchh--pprroobbaabbiilliittiieess), or for test coverage analysis (--fftteesstt--ccoovveerraaggee). Each object file's _a_u_x_n_a_m_e is generated from the name of the output file, if explicitly specified and it is not the final executable, otherwise it is the basename of the source file. In both cases any suffix is removed (e.g. _f_o_o_._g_c_d_a for input file _d_i_r_/_f_o_o_._c, or _d_i_r_/_f_o_o_._g_c_d_a for output file specified as --oo ddiirr//ffoooo..oo). Note that if a command line directly links source files, the corre- sponding _._g_c_d_a files will be prefixed with the unsuffixed name of the output file. E.g. "gcc a.c b.c -o binary" would generate _b_i_- _n_a_r_y_-_a_._g_c_d_a and _b_i_n_a_r_y_-_b_._g_c_d_a files. ----ccoovveerraaggee This option is used to compile and link code instrumented for cov- erage analysis. The option is a synonym for --ffpprrooffiillee--aarrccss --fftteesstt--ccoovveerraaggee (when compiling) and --llggccoovv (when linking). See the documentation for those options for more details. * Compile the source files with --ffpprrooffiillee--aarrccss plus optimization and code generation options. For test coverage analysis, use the additional --fftteesstt--ccoovveerraaggee option. You do not need to pro- file every source file in a program. * Compile the source files additionally with --ffpprrooffiillee--aabbss--ppaatthh to create absolute path names in the _._g_c_n_o files. This allows ggccoovv to find the correct sources in projects where compilations occur with different working directories. * Link your object files with --llggccoovv or --ffpprrooffiillee--aarrccss (the lat- ter implies the former). * Run the program on a representative workload to generate the arc profile information. This may be repeated any number of times. You can run concurrent instances of your program, and provided that the file system supports locking, the data files will be correctly updated. Unless a strict ISO C dialect op- tion is in effect, "fork" calls are detected and correctly han- dled without double counting. Moreover, an object file can be recompiled multiple times and the corresponding _._g_c_d_a file merges as long as the source file and the compiler options are unchanged. * For profile-directed optimizations, compile the source files again with the same optimization and code generation options plus --ffbbrraanncchh--pprroobbaabbiilliittiieess. * For test coverage analysis, use ggccoovv to produce human readable information from the _._g_c_n_o and _._g_c_d_a files. Refer to the ggccoovv documentation for further information. With --ffpprrooffiillee--aarrccss, for each function of your program GCC creates a program flow graph, then finds a spanning tree for the graph. Only arcs that are not on the spanning tree have to be instru- mented: the compiler adds code to count the number of times that these arcs are executed. When an arc is the only exit or only en- trance to a block, the instrumentation code can be added to the block; otherwise, a new basic block must be created to hold the in- strumentation code. --fftteesstt--ccoovveerraaggee Produce a notes file that the ggccoovv code-coverage utility can use to show program coverage. Each source file's note file is called _a_u_x_- _n_a_m_e_._g_c_n_o. Refer to the --ffpprrooffiillee--aarrccss option above for a descrip- tion of _a_u_x_n_a_m_e and instructions on how to generate test coverage data. Coverage data matches the source files more closely if you do not optimize. --ffpprrooffiillee--aabbss--ppaatthh Automatically convert relative source file names to absolute path names in the _._g_c_n_o files. This allows ggccoovv to find the correct sources in projects where compilations occur with different working directories. --ffpprrooffiillee--ddiirr==_p_a_t_h Set the directory to search for the profile data files in to _p_a_t_h. This option affects only the profile data generated by --ffpprroo-- ffiillee--ggeenneerraattee, --fftteesstt--ccoovveerraaggee, --ffpprrooffiillee--aarrccss and used by --ffpprroo-- ffiillee--uussee and --ffbbrraanncchh--pprroobbaabbiilliittiieess and its related options. Both absolute and relative paths can be used. By default, GCC uses the current directory as _p_a_t_h, thus the profile data file appears in the same directory as the object file. In order to prevent the file name clashing, if the object file name is not an absolute path, we mangle the absolute path of the _s_o_u_r_c_e_n_a_m_e_._g_c_d_a file and use it as the file name of a _._g_c_d_a file. See details about the file naming in --ffpprrooffiillee--aarrccss. See similar option --ffpprrooffiillee--nnoottee. When an executable is run in a massive parallel environment, it is recommended to save profile to different folders. That can be done with variables in _p_a_t_h that are exported during run-time: %%pp process ID. %%qq{{VVAARR}} value of environment variable _V_A_R --ffpprrooffiillee--ggeenneerraattee --ffpprrooffiillee--ggeenneerraattee==_p_a_t_h Enable options usually used for instrumenting application to pro- duce profile useful for later recompilation with profile feedback based optimization. You must use --ffpprrooffiillee--ggeenneerraattee both when com- piling and when linking your program. The following options are enabled: --ffpprrooffiillee--aarrccss, --ffpprrooffiillee--vvaall-- uueess, --ffiinnlliinnee--ffuunnccttiioonnss, and --ffiippaa--bbiitt--ccpp. If _p_a_t_h is specified, GCC looks at the _p_a_t_h to find the profile feedback data files. See --ffpprrooffiillee--ddiirr. To optimize the program based on the collected profile information, use --ffpprrooffiillee--uussee. --ffpprrooffiillee--iinnffoo--sseeccttiioonn --ffpprrooffiillee--iinnffoo--sseeccttiioonn==_n_a_m_e Register the profile information in the specified section instead of using a constructor/destructor. The section name is _n_a_m_e if it is specified, otherwise the section name defaults to ".gcov_info". A pointer to the profile information generated by --ffpprrooffiillee--aarrccss is placed in the specified section for each translation unit. This option disables the profile information registration through a con- structor and it disables the profile information processing through a destructor. This option is not intended to be used in hosted en- vironments such as GNU/Linux. It targets free-standing environ- ments (for example embedded systems) with limited resources which do not support constructors/destructors or the C library file I/O. The linker could collect the input sections in a continuous memory block and define start and end symbols. A GNU linker script exam- ple which defines a linker output section follows: .gcov_info : { PROVIDE (__gcov_info_start = .); KEEP (*(.gcov_info)) PROVIDE (__gcov_info_end = .); } The program could dump the profiling information registered in this linker set for example like this: #include #include #include extern const struct gcov_info *__gcov_info_start[]; extern const struct gcov_info *__gcov_info_end[]; static void filename (const char *f, void *arg) { puts (f); } static void dump (const void *d, unsigned n, void *arg) { const unsigned char *c = d; for (unsigned i = 0; i < n; ++i) printf ("%02x", c[i]); } static void * allocate (unsigned length, void *arg) { return malloc (length); } static void dump_gcov_info (void) { const struct gcov_info **info = __gcov_info_start; const struct gcov_info **end = __gcov_info_end; /* Obfuscate variable to prevent compiler optimizations. */ __asm__ ("" : "+r" (info)); while (info != end) { void *arg = NULL; __gcov_info_to_gcda (*info, filename, dump, allocate, arg); putchar ('\n'); ++info; } } int main() { dump_gcov_info(); return 0; } --ffpprrooffiillee--nnoottee==_p_a_t_h If _p_a_t_h is specified, GCC saves _._g_c_n_o file into _p_a_t_h location. If you combine the option with multiple source files, the _._g_c_n_o file will be overwritten. --ffpprrooffiillee--pprreeffiixx--ppaatthh==_p_a_t_h This option can be used in combination with pprrooffiillee--ggeenneerraattee==_p_r_o_- _f_i_l_e___d_i_r and pprrooffiillee--uussee==_p_r_o_f_i_l_e___d_i_r to inform GCC where is the base directory of built source tree. By default _p_r_o_f_i_l_e___d_i_r will contain files with mangled absolute paths of all object files in the built project. This is not desirable when directory used to build the instrumented binary differs from the directory used to build the binary optimized with profile feedback because the pro- file data will not be found during the optimized build. In such setups --ffpprrooffiillee--pprreeffiixx--ppaatthh==_p_a_t_h with _p_a_t_h pointing to the base directory of the build can be used to strip the irrelevant part of the path and keep all file names relative to the main build direc- tory. --ffpprrooffiillee--pprreeffiixx--mmaapp==_o_l_d==_n_e_w When compiling files residing in directory _o_l_d, record profiling information (with ----ccoovveerraaggee) describing them as if the files resided in directory _n_e_w instead. See also --ffffiillee--pprreeffiixx--mmaapp. --ffpprrooffiillee--uuppddaattee==_m_e_t_h_o_d Alter the update method for an application instrumented for profile feedback based optimization. The _m_e_t_h_o_d argument should be one of ssiinnggllee, aattoommiicc or pprreeffeerr--aattoommiicc. The first one is useful for sin- gle-threaded applications, while the second one prevents profile corruption by emitting thread-safe code. WWaarrnniinngg:: When an application does not properly join all threads (or creates an detached thread), a profile file can be still corrupted. Using pprreeffeerr--aattoommiicc would be transformed either to aattoommiicc, when supported by a target, or to ssiinnggllee otherwise. The GCC driver au- tomatically selects pprreeffeerr--aattoommiicc when --pptthhrreeaadd is present in the command line. --ffpprrooffiillee--ffiilltteerr--ffiilleess==_r_e_g_e_x Instrument only functions from files whose name matches any of the regular expressions (separated by semi-colons). For example, --ffpprrooffiillee--ffiilltteerr--ffiilleess==mmaaiinn\\..cc;;mmoodduullee..**\\..cc will in- strument only _m_a_i_n_._c and all C files starting with 'module'. --ffpprrooffiillee--eexxcclluuddee--ffiilleess==_r_e_g_e_x Instrument only functions from files whose name does not match any of the regular expressions (separated by semi-colons). For example, --ffpprrooffiillee--eexxcclluuddee--ffiilleess==//uussrr//..** will prevent instru- mentation of all files that are located in the _/_u_s_r_/ folder. --ffpprrooffiillee--rreepprroodduucciibbllee==[mmuullttiitthhrreeaaddeedd|ppaarraalllleell--rruunnss|sseerriiaall] Control level of reproducibility of profile gathered by "-fpro- file-generate". This makes it possible to rebuild program with same outcome which is useful, for example, for distribution pack- ages. With --ffpprrooffiillee--rreepprroodduucciibbllee==sseerriiaall the profile gathered by --ffpprroo-- ffiillee--ggeenneerraattee is reproducible provided the trained program behaves the same at each invocation of the train run, it is not multi- threaded and profile data streaming is always done in the same or- der. Note that profile streaming happens at the end of program run but also before "fork" function is invoked. Note that it is quite common that execution counts of some part of programs depends, for example, on length of temporary file names or memory space randomization (that may affect hash-table collision rate). Such non-reproducible part of programs may be annotated by "no_instrument_function" function attribute. ggccoovv--dduummpp with --ll can be used to dump gathered data and verify that they are indeed re- producible. With --ffpprrooffiillee--rreepprroodduucciibbllee==ppaarraalllleell--rruunnss collected profile stays reproducible regardless the order of streaming of the data into gcda files. This setting makes it possible to run multiple in- stances of instrumented program in parallel (such as with "make -j"). This reduces quality of gathered data, in particular of indi- rect call profiling. --ffssaanniittiizzee==aaddddrreessss Enable AddressSanitizer, a fast memory error detector. Memory ac- cess instructions are instrumented to detect out-of-bounds and use- after-free bugs. The option enables --ffssaanniittiizzee--aaddddrreessss--uussee--aaff-- tteerr--ssccooppee. See for more details. The run-time behavior can be influ- enced using the AASSAANN__OOPPTTIIOONNSS environment variable. When set to "help=1", the available options are shown at startup of the instru- mented program. See for a list of supported op- tions. The option cannot be combined with --ffssaanniittiizzee==tthhrreeaadd or --ffssaanniittiizzee==hhwwaaddddrreessss. Note that the only target --ffssaanniittiizzee==hhwwaadd-- ddrreessss is currently supported on is AArch64. --ffssaanniittiizzee==kkeerrnneell--aaddddrreessss Enable AddressSanitizer for Linux kernel. See for more details. --ffssaanniittiizzee==hhwwaaddddrreessss Enable Hardware-assisted AddressSanitizer, which uses a hardware ability to ignore the top byte of a pointer to allow the detection of memory errors with a low memory overhead. Memory access in- structions are instrumented to detect out-of-bounds and use-after- free bugs. The option enables --ffssaanniittiizzee--aaddddrreessss--uussee--aafftteerr--ssccooppee. See for more details. The run-time behavior can be in- fluenced using the HHWWAASSAANN__OOPPTTIIOONNSS environment variable. When set to "help=1", the available options are shown at startup of the in- strumented program. The option cannot be combined with --ffssaannii-- ttiizzee==tthhrreeaadd or --ffssaanniittiizzee==aaddddrreessss, and is currently only available on AArch64. --ffssaanniittiizzee==kkeerrnneell--hhwwaaddddrreessss Enable Hardware-assisted AddressSanitizer for compilation of the Linux kernel. Similar to --ffssaanniittiizzee==kkeerrnneell--aaddddrreessss but using an alternate instrumentation method, and similar to --ffssaanniittiizzee==hhwwaadd-- ddrreessss but with instrumentation differences necessary for compiling the Linux kernel. These differences are to avoid hwasan library initialization calls and to account for the stack pointer having a different value in its top byte. _N_o_t_e_: This option has different defaults to the --ffssaanniittiizzee==hhwwaadd-- ddrreessss. Instrumenting the stack and alloca calls are not on by de- fault but are still possible by specifying the command-line options ----ppaarraamm hhwwaassaann--iinnssttrruummeenntt--ssttaacckk==11 and ----ppaarraamm hhwwaassaann--iinnssttrruummeenntt--aall-- llooccaass==11 respectively. Using a random frame tag is not implemented for kernel instrumentation. --ffssaanniittiizzee==ppooiinntteerr--ccoommppaarree Instrument comparison operation (<, <=, >, >=) with pointer oper- ands. The option must be combined with either --ffssaanniittiizzee==kkeerr-- nneell--aaddddrreessss or --ffssaanniittiizzee==aaddddrreessss The option cannot be combined with --ffssaanniittiizzee==tthhrreeaadd. Note: By default the check is disabled at run time. To enable it, add "detect_invalid_pointer_pairs=2" to the environment variable AASSAANN__OOPPTTIIOONNSS. Using "detect_in- valid_pointer_pairs=1" detects invalid operation only when both pointers are non-null. --ffssaanniittiizzee==ppooiinntteerr--ssuubbttrraacctt Instrument subtraction with pointer operands. The option must be combined with either --ffssaanniittiizzee==kkeerrnneell--aaddddrreessss or --ffssaanniittiizzee==aadd-- ddrreessss The option cannot be combined with --ffssaanniittiizzee==tthhrreeaadd. Note: By default the check is disabled at run time. To enable it, add "detect_invalid_pointer_pairs=2" to the environment variable AASSAANN__OOPPTTIIOONNSS. Using "detect_invalid_pointer_pairs=1" detects in- valid operation only when both pointers are non-null. --ffssaanniittiizzee==sshhaaddooww--ccaallll--ssttaacckk Enable ShadowCallStack, a security enhancement mechanism used to protect programs against return address overwrites (e.g. stack buf- fer overflows.) It works by saving a function's return address to a separately allocated shadow call stack in the function prologue and restoring the return address from the shadow call stack in the function epilogue. Instrumentation only occurs in functions that need to save the return address to the stack. Currently it only supports the aarch64 platform. It is specifi- cally designed for linux kernels that enable the CON- FIG_SHADOW_CALL_STACK option. For the user space programs, runtime support is not currently provided in libc and libgcc. Users who want to use this feature in user space need to provide their own support for the runtime. It should be noted that this may cause the ABI rules to be broken. On aarch64, the instrumentation makes use of the platform register "x18". This generally means that any code that may run on the same thread as code compiled with ShadowCallStack must be compiled with the flag --ffffiixxeedd--xx1188, otherwise functions compiled without --ffffiixxeedd--xx1188 might clobber "x18" and so corrupt the shadow stack pointer. Also, because there is no userspace runtime support, code compiled with ShadowCallStack cannot use exception handling. Use --ffnnoo--eexx-- cceeppttiioonnss to turn off exceptions. See for more de- tails. --ffssaanniittiizzee==tthhrreeaadd Enable ThreadSanitizer, a fast data race detector. Memory access instructions are instrumented to detect data race bugs. See for more details. The run-time behavior can be influenced using the TTSSAANN__OOPPTTIIOONNSS environment variable; see for a list of supported options. The option cannot be combined with --ffssaanniittiizzee==aaddddrreessss, --ffssaanniittiizzee==lleeaakk. Note that sanitized atomic builtins cannot throw exceptions when operating on invalid memory addresses with non-call exceptions (--ffnnoonn--ccaallll--eexxcceeppttiioonnss). --ffssaanniittiizzee==lleeaakk Enable LeakSanitizer, a memory leak detector. This option only matters for linking of executables and the executable is linked against a library that overrides "malloc" and other allocator func- tions. See for more details. The run-time behavior can be influenced using the LLSSAANN__OOPPTTIIOONNSS environment variable. The option cannot be combined with --ffssaanniittiizzee==tthhrreeaadd. --ffssaanniittiizzee==uunnddeeffiinneedd Enable UndefinedBehaviorSanitizer, a fast undefined behavior detec- tor. Various computations are instrumented to detect undefined be- havior at runtime. See for more details. The run-time behavior can be influenced using the UUBBSSAANN__OOPPTTIIOONNSS environment variable. Cur- rent suboptions are: --ffssaanniittiizzee==sshhiifftt This option enables checking that the result of a shift opera- tion is not undefined. Note that what exactly is considered undefined differs slightly between C and C++, as well as be- tween ISO C90 and C99, etc. This option has two suboptions, --ffssaanniittiizzee==sshhiifftt--bbaassee and --ffssaanniittiizzee==sshhiifftt--eexxppoonneenntt. --ffssaanniittiizzee==sshhiifftt--eexxppoonneenntt This option enables checking that the second argument of a shift operation is not negative and is smaller than the preci- sion of the promoted first argument. --ffssaanniittiizzee==sshhiifftt--bbaassee If the second argument of a shift operation is within range, check that the result of a shift operation is not undefined. Note that what exactly is considered undefined differs slightly between C and C++, as well as between ISO C90 and C99, etc. --ffssaanniittiizzee==iinntteeggeerr--ddiivviiddee--bbyy--zzeerroo Detect integer division by zero. --ffssaanniittiizzee==uunnrreeaacchhaabbllee With this option, the compiler turns the "__builtin_unreach- able" call into a diagnostics message call instead. When reaching the "__builtin_unreachable" call, the behavior is un- defined. --ffssaanniittiizzee==vvllaa--bboouunndd This option instructs the compiler to check that the size of a variable length array is positive. --ffssaanniittiizzee==nnuullll This option enables pointer checking. Particularly, the appli- cation built with this option turned on will issue an error message when it tries to dereference a NULL pointer, or if a reference (possibly an rvalue reference) is bound to a NULL pointer, or if a method is invoked on an object pointed by a NULL pointer. --ffssaanniittiizzee==rreettuurrnn This option enables return statement checking. Programs built with this option turned on will issue an error message when the end of a non-void function is reached without actually return- ing a value. This option works in C++ only. --ffssaanniittiizzee==ssiiggnneedd--iinntteeggeerr--oovveerrffllooww This option enables signed integer overflow checking. We check that the result of "+", "*", and both unary and binary "-" does not overflow in the signed arithmetics. This also detects "INT_MIN / -1" signed division. Note, integer promotion rules must be taken into account. That is, the following is not an overflow: signed char a = SCHAR_MAX; a++; --ffssaanniittiizzee==bboouunnddss This option enables instrumentation of array bounds. Various out of bounds accesses are detected. Flexible array members, flexible array member-like arrays, and initializers of vari- ables with static storage are not instrumented. --ffssaanniittiizzee==bboouunnddss--ssttrriicctt This option enables strict instrumentation of array bounds. Most out of bounds accesses are detected, including flexible array members and flexible array member-like arrays. Initial- izers of variables with static storage are not instrumented. --ffssaanniittiizzee==aalliiggnnmmeenntt This option enables checking of alignment of pointers when they are dereferenced, or when a reference is bound to insuffi- ciently aligned target, or when a method or constructor is in- voked on insufficiently aligned object. --ffssaanniittiizzee==oobbjjeecctt--ssiizzee This option enables instrumentation of memory references using the "__builtin_object_size" function. Various out of bounds pointer accesses are detected. --ffssaanniittiizzee==ffllooaatt--ddiivviiddee--bbyy--zzeerroo Detect floating-point division by zero. Unlike other similar options, --ffssaanniittiizzee==ffllooaatt--ddiivviiddee--bbyy--zzeerroo is not enabled by --ffssaanniittiizzee==uunnddeeffiinneedd, since floating-point division by zero can be a legitimate way of obtaining infinities and NaNs. --ffssaanniittiizzee==ffllooaatt--ccaasstt--oovveerrffllooww This option enables floating-point type to integer conversion checking. We check that the result of the conversion does not overflow. Unlike other similar options, --ffssaannii-- ttiizzee==ffllooaatt--ccaasstt--oovveerrffllooww is not enabled by --ffssaanniittiizzee==uunnddee-- ffiinneedd. This option does not work well with "FE_INVALID" excep- tions enabled. --ffssaanniittiizzee==nnoonnnnuullll--aattttrriibbuuttee This option enables instrumentation of calls, checking whether null values are not passed to arguments marked as requiring a non-null value by the "nonnull" function attribute. --ffssaanniittiizzee==rreettuurrnnss--nnoonnnnuullll--aattttrriibbuuttee This option enables instrumentation of return statements in functions marked with "returns_nonnull" function attribute, to detect returning of null values from such functions. --ffssaanniittiizzee==bbooooll This option enables instrumentation of loads from bool. If a value other than 0/1 is loaded, a run-time error is issued. --ffssaanniittiizzee==eennuumm This option enables instrumentation of loads from an enum type. If a value outside the range of values for the enum type is loaded, a run-time error is issued. --ffssaanniittiizzee==vvppttrr This option enables instrumentation of C++ member function calls, member accesses and some conversions between pointers to base and derived classes, to verify the referenced object has the correct dynamic type. --ffssaanniittiizzee==ppooiinntteerr--oovveerrffllooww This option enables instrumentation of pointer arithmetics. If the pointer arithmetics overflows, a run-time error is issued. --ffssaanniittiizzee==bbuuiillttiinn This option enables instrumentation of arguments to selected builtin functions. If an invalid value is passed to such argu- ments, a run-time error is issued. E.g. passing 0 as the argu- ment to "__builtin_ctz" or "__builtin_clz" invokes undefined behavior and is diagnosed by this option. While --ffttrraappvv causes traps for signed overflows to be emitted, --ffssaanniittiizzee==uunnddeeffiinneedd gives a diagnostic message. This currently works only for the C family of languages. --ffnnoo--ssaanniittiizzee==aallll This option disables all previously enabled sanitizers. --ffssaannii-- ttiizzee==aallll is not allowed, as some sanitizers cannot be used to- gether. --ffaassaann--sshhaaddooww--ooffffsseett==_n_u_m_b_e_r This option forces GCC to use custom shadow offset in AddressSani- tizer checks. It is useful for experimenting with different shadow memory layouts in Kernel AddressSanitizer. --ffssaanniittiizzee--sseeccttiioonnss==_s_1,,_s_2,,...... Sanitize global variables in selected user-defined sections. _s_i may contain wildcards. --ffssaanniittiizzee--rreeccoovveerr[==_o_p_t_s] --ffssaanniittiizzee--rreeccoovveerr== controls error recovery mode for sanitizers mentioned in comma-separated list of _o_p_t_s. Enabling this option for a sanitizer component causes it to attempt to continue running the program as if no error happened. This means multiple runtime errors can be reported in a single program run, and the exit code of the program may indicate success even when errors have been re- ported. The --ffnnoo--ssaanniittiizzee--rreeccoovveerr== option can be used to alter this behavior: only the first detected error is reported and pro- gram then exits with a non-zero exit code. Currently this feature only works for --ffssaanniittiizzee==uunnddeeffiinneedd (and its suboptions except for --ffssaanniittiizzee==uunnrreeaacchhaabbllee and --ffssaanniittiizzee==rree-- ttuurrnn), --ffssaanniittiizzee==ffllooaatt--ccaasstt--oovveerrffllooww, --ffssaanniittiizzee==ffllooaatt--ddii-- vviiddee--bbyy--zzeerroo, --ffssaanniittiizzee==bboouunnddss--ssttrriicctt, --ffssaanniittiizzee==kkeerrnneell--aaddddrreessss and --ffssaanniittiizzee==aaddddrreessss. For these sanitizers error recovery is turned on by default, except --ffssaanniittiizzee==aaddddrreessss, for which this feature is experimental. --ffssaanniittiizzee--rreeccoovveerr==aallll and --ffnnoo--ssaannii-- ttiizzee--rreeccoovveerr==aallll is also accepted, the former enables recovery for all sanitizers that support it, the latter disables recovery for all sanitizers that support it. Even if a recovery mode is turned on the compiler side, it needs to be also enabled on the runtime library side, otherwise the failures are still fatal. The runtime library defaults to "halt_on_error=0" for ThreadSanitizer and UndefinedBehaviorSanitizer, while default value for AddressSanitizer is "halt_on_error=1". This can be over- ridden through setting the "halt_on_error" flag in the correspond- ing environment variable. Syntax without an explicit _o_p_t_s parameter is deprecated. It is equivalent to specifying an _o_p_t_s list of: undefined,float-cast-overflow,float-divide-by-zero,bounds-strict --ffssaanniittiizzee--aaddddrreessss--uussee--aafftteerr--ssccooppee Enable sanitization of local variables to detect use-after-scope bugs. The option sets --ffssttaacckk--rreeuussee to nnoonnee. --ffssaanniittiizzee--uunnddeeffiinneedd--ttrraapp--oonn--eerrrroorr The --ffssaanniittiizzee--uunnddeeffiinneedd--ttrraapp--oonn--eerrrroorr option instructs the com- piler to report undefined behavior using "__builtin_trap" rather than a "libubsan" library routine. The advantage of this is that the "libubsan" library is not needed and is not linked in, so this is usable even in freestanding environments. --ffssaanniittiizzee--ccoovveerraaggee==ttrraaccee--ppcc Enable coverage-guided fuzzing code instrumentation. Inserts a call to "__sanitizer_cov_trace_pc" into every basic block. --ffssaanniittiizzee--ccoovveerraaggee==ttrraaccee--ccmmpp Enable dataflow guided fuzzing code instrumentation. Inserts a call to "__sanitizer_cov_trace_cmp1", "__sanitizer_cov_trace_cmp2", "__sanitizer_cov_trace_cmp4" or "__sanitizer_cov_trace_cmp8" for integral comparison with both operands variable or "__sani- tizer_cov_trace_const_cmp1", "__sanitizer_cov_trace_const_cmp2", "__sanitizer_cov_trace_const_cmp4" or "__sani- tizer_cov_trace_const_cmp8" for integral comparison with one oper- and constant, "__sanitizer_cov_trace_cmpf" or "__sani- tizer_cov_trace_cmpd" for float or double comparisons and "__sani- tizer_cov_trace_switch" for switch statements. --ffccff--pprrootteeccttiioonn==[ffuullll|bbrraanncchh|rreettuurrnn|nnoonnee|cchheecckk] Enable code instrumentation of control-flow transfers to increase program security by checking that target addresses of control-flow transfer instructions (such as indirect function call, function re- turn, indirect jump) are valid. This prevents diverting the flow of control to an unexpected target. This is intended to protect against such threats as Return-oriented Programming (ROP), and sim- ilarly call/jmp-oriented programming (COP/JOP). The value "branch" tells the compiler to implement checking of va- lidity of control-flow transfer at the point of indirect branch in- structions, i.e. call/jmp instructions. The value "return" imple- ments checking of validity at the point of returning from a func- tion. The value "full" is an alias for specifying both "branch" and "return". The value "none" turns off instrumentation. The value "check" is used for the final link with link-time opti- mization (LTO). An error is issued if LTO object files are com- piled with different --ffccff--pprrootteeccttiioonn values. The value "check" is ignored at the compile time. The macro "__CET__" is defined when --ffccff--pprrootteeccttiioonn is used. The first bit of "__CET__" is set to 1 for the value "branch" and the second bit of "__CET__" is set to 1 for the "return". You can also use the "nocf_check" attribute to identify which func- tions and calls should be skipped from instrumentation. Currently the x86 GNU/Linux target provides an implementation based on Intel Control-flow Enforcement Technology (CET) which works for i686 processor or newer. --ffhhaarrddeenn--ccoommppaarreess For every logical test that survives gimple optimizations and is _n_o_t the condition in a conditional branch (for example, conditions tested for conditional moves, or to store in boolean variables), emit extra code to compute and verify the reversed condition, and to call "__builtin_trap" if the results do not match. Use with --ffhhaarrddeenn--ccoonnddiittiioonnaall--bbrraanncchheess to cover all conditionals. --ffhhaarrddeenn--ccoonnddiittiioonnaall--bbrraanncchheess For every non-vectorized conditional branch that survives gimple optimizations, emit extra code to compute and verify the reversed condition, and to call "__builtin_trap" if the result is unex- pected. Use with --ffhhaarrddeenn--ccoommppaarreess to cover all conditionals. --ffssttaacckk--pprrootteeccttoorr Emit extra code to check for buffer overflows, such as stack smash- ing attacks. This is done by adding a guard variable to functions with vulnerable objects. This includes functions that call "al- loca", and functions with buffers larger than or equal to 8 bytes. The guards are initialized when a function is entered and then checked when the function exits. If a guard check fails, an error message is printed and the program exits. Only variables that are actually allocated on the stack are considered, optimized away variables or variables allocated in registers don't count. --ffssttaacckk--pprrootteeccttoorr--aallll Like --ffssttaacckk--pprrootteeccttoorr except that all functions are protected. --ffssttaacckk--pprrootteeccttoorr--ssttrroonngg Like --ffssttaacckk--pprrootteeccttoorr but includes additional functions to be pro- tected --- those that have local array definitions, or have refer- ences to local frame addresses. Only variables that are actually allocated on the stack are considered, optimized away variables or variables allocated in registers don't count. --ffssttaacckk--pprrootteeccttoorr--eexxpplliicciitt Like --ffssttaacckk--pprrootteeccttoorr but only protects those functions which have the "stack_protect" attribute. --ffssttaacckk--cchheecckk Generate code to verify that you do not go beyond the boundary of the stack. You should specify this flag if you are running in an environment with multiple threads, but you only rarely need to specify it in a single-threaded environment since stack overflow is automatically detected on nearly all systems if there is only one stack. Note that this switch does not actually cause checking to be done; the operating system or the language runtime must do that. The switch causes generation of code to ensure that they see the stack being extended. You can additionally specify a string parameter: nnoo means no check- ing, ggeenneerriicc means force the use of old-style checking, ssppeecciiffiicc means use the best checking method and is equivalent to bare --ffss-- ttaacckk--cchheecckk. Old-style checking is a generic mechanism that requires no specific target support in the compiler but comes with the following draw- backs: 1. Modified allocation strategy for large objects: they are always allocated dynamically if their size exceeds a fixed threshold. Note this may change the semantics of some code. 2. Fixed limit on the size of the static frame of functions: when it is topped by a particular function, stack checking is not reliable and a warning is issued by the compiler. 3. Inefficiency: because of both the modified allocation strategy and the generic implementation, code performance is hampered. Note that old-style stack checking is also the fallback method for ssppeecciiffiicc if no target support has been added in the compiler. --ffssttaacckk--cchheecckk== is designed for Ada's needs to detect infinite re- cursion and stack overflows. ssppeecciiffiicc is an excellent choice when compiling Ada code. It is not generally sufficient to protect against stack-clash attacks. To protect against those you want --ffssttaacckk--ccllaasshh--pprrootteeccttiioonn. --ffssttaacckk--ccllaasshh--pprrootteeccttiioonn Generate code to prevent stack clash style attacks. When this op- tion is enabled, the compiler will only allocate one page of stack space at a time and each page is accessed immediately after alloca- tion. Thus, it prevents allocations from jumping over any stack guard page provided by the operating system. Most targets do not fully support stack clash protection. However, on those targets --ffssttaacckk--ccllaasshh--pprrootteeccttiioonn will protect dynamic stack allocations. --ffssttaacckk--ccllaasshh--pprrootteeccttiioonn may also provide lim- ited protection for static stack allocations if the target supports --ffssttaacckk--cchheecckk==ssppeecciiffiicc. --ffssttaacckk--lliimmiitt--rreeggiisstteerr==_r_e_g --ffssttaacckk--lliimmiitt--ssyymmbbooll==_s_y_m --ffnnoo--ssttaacckk--lliimmiitt Generate code to ensure that the stack does not grow beyond a cer- tain value, either the value of a register or the address of a sym- bol. If a larger stack is required, a signal is raised at run time. For most targets, the signal is raised before the stack overruns the boundary, so it is possible to catch the signal with- out taking special precautions. For instance, if the stack starts at absolute address 00xx8800000000000000 and grows downwards, you can use the flags --ffssttaacckk--lliimmiitt--ssyymm-- bbooll==____ssttaacckk__lliimmiitt and --WWll,,----ddeeffssyymm,,____ssttaacckk__lliimmiitt==00xx77ffffee00000000 to en- force a stack limit of 128KB. Note that this may only work with the GNU linker. You can locally override stack limit checking by using the "no_stack_limit" function attribute. --ffsspplliitt--ssttaacckk Generate code to automatically split the stack before it overflows. The resulting program has a discontiguous stack which can only overflow if the program is unable to allocate any more memory. This is most useful when running threaded programs, as it is no longer necessary to calculate a good stack size to use for each thread. This is currently only implemented for the x86 targets running GNU/Linux. When code compiled with --ffsspplliitt--ssttaacckk calls code compiled without --ffsspplliitt--ssttaacckk, there may not be much stack space available for the latter code to run. If compiling all code, including library code, with --ffsspplliitt--ssttaacckk is not an option, then the linker can fix up these calls so that the code compiled without --ffsspplliitt--ssttaacckk always has a large stack. Support for this is implemented in the gold linker in GNU binutils release 2.21 and later. --ffvvttaabbllee--vveerriiffyy==[ssttdd|pprreeiinniitt|nnoonnee] This option is only available when compiling C++ code. It turns on (or off, if using --ffvvttaabbllee--vveerriiffyy==nnoonnee) the security feature that verifies at run time, for every virtual call, that the vtable pointer through which the call is made is valid for the type of the object, and has not been corrupted or overwritten. If an invalid vtable pointer is detected at run time, an error is reported and execution of the program is immediately halted. This option causes run-time data structures to be built at program startup, which are used for verifying the vtable pointers. The op- tions ssttdd and pprreeiinniitt control the timing of when these data struc- tures are built. In both cases the data structures are built be- fore execution reaches "main". Using --ffvvttaabbllee--vveerriiffyy==ssttdd causes the data structures to be built after shared libraries have been loaded and initialized. --ffvvttaabbllee--vveerriiffyy==pprreeiinniitt causes them to be built before shared libraries have been loaded and initialized. If this option appears multiple times in the command line with dif- ferent values specified, nnoonnee takes highest priority over both ssttdd and pprreeiinniitt; pprreeiinniitt takes priority over ssttdd. --ffvvttvv--ddeebbuugg When used in conjunction with --ffvvttaabbllee--vveerriiffyy==ssttdd or --ffvvttaabbllee--vveerr-- iiffyy==pprreeiinniitt, causes debug versions of the runtime functions for the vtable verification feature to be called. This flag also causes the compiler to log information about which vtable pointers it finds for each class. This information is written to a file named _v_t_v___s_e_t___p_t_r___d_a_t_a_._l_o_g in the directory named by the environment variable VVTTVV__LLOOGGSS__DDIIRR if that is defined or the current working di- rectory otherwise. Note: This feature _a_p_p_e_n_d_s data to the log file. If you want a fresh log file, be sure to delete any existing one. --ffvvttvv--ccoouunnttss This is a debugging flag. When used in conjunction with --ffvvttaabbllee--vveerriiffyy==ssttdd or --ffvvttaabbllee--vveerriiffyy==pprreeiinniitt, this causes the compiler to keep track of the total number of virtual calls it en- counters and the number of verifications it inserts. It also counts the number of calls to certain run-time library functions that it inserts and logs this information for each compilation unit. The compiler writes this information to a file named _v_t_v___c_o_u_n_t___d_a_t_a_._l_o_g in the directory named by the environment vari- able VVTTVV__LLOOGGSS__DDIIRR if that is defined or the current working direc- tory otherwise. It also counts the size of the vtable pointer sets for each class, and writes this information to _v_t_v___c_l_a_s_s___s_e_t___s_i_z_e_s_._l_o_g in the same directory. Note: This feature _a_p_p_e_n_d_s data to the log files. To get fresh log files, be sure to delete any existing ones. --ffiinnssttrruummeenntt--ffuunnccttiioonnss Generate instrumentation calls for entry and exit to functions. Just after function entry and just before function exit, the fol- lowing profiling functions are called with the address of the cur- rent function and its call site. (On some platforms, "__builtin_return_address" does not work beyond the current func- tion, so the call site information may not be available to the pro- filing functions otherwise.) void __cyg_profile_func_enter (void *this_fn, void *call_site); void __cyg_profile_func_exit (void *this_fn, void *call_site); The first argument is the address of the start of the current func- tion, which may be looked up exactly in the symbol table. This instrumentation is also done for functions expanded inline in other functions. The profiling calls indicate where, conceptually, the inline function is entered and exited. This means that ad- dressable versions of such functions must be available. If all your uses of a function are expanded inline, this may mean an addi- tional expansion of code size. If you use "extern inline" in your C code, an addressable version of such functions must be provided. (This is normally the case anyway, but if you get lucky and the op- timizer always expands the functions inline, you might have gotten away without providing static copies.) A function may be given the attribute "no_instrument_function", in which case this instrumentation is not done. This can be used, for example, for the profiling functions listed above, high-priority interrupt routines, and any functions from which the profiling functions cannot safely be called (perhaps signal handlers, if the profiling routines generate output or allocate memory). --ffiinnssttrruummeenntt--ffuunnccttiioonnss--eexxcclluuddee--ffiillee--lliisstt==_f_i_l_e,,_f_i_l_e,,...... Set the list of functions that are excluded from instrumentation (see the description of --ffiinnssttrruummeenntt--ffuunnccttiioonnss). If the file that contains a function definition matches with one of _f_i_l_e, then that function is not instrumented. The match is done on substrings: if the _f_i_l_e parameter is a substring of the file name, it is consid- ered to be a match. For example: -finstrument-functions-exclude-file-list=/bits/stl,include/sys excludes any inline function defined in files whose pathnames con- tain _/_b_i_t_s_/_s_t_l or _i_n_c_l_u_d_e_/_s_y_s. If, for some reason, you want to include letter ,, in one of _s_y_m, write ,,. For example, --ffiinnssttrruummeenntt--ffuunnccttiioonnss--eexx-- cclluuddee--ffiillee--lliisstt=='',,,,ttmmpp'' (note the single quote surrounding the op- tion). --ffiinnssttrruummeenntt--ffuunnccttiioonnss--eexxcclluuddee--ffuunnccttiioonn--lliisstt==_s_y_m,,_s_y_m,,...... This is similar to --ffiinnssttrruummeenntt--ffuunnccttiioonnss--eexxcclluuddee--ffiillee--lliisstt, but this option sets the list of function names to be excluded from in- strumentation. The function name to be matched is its user-visible name, such as "vector blah(const vector &)", not the in- ternal mangled name (e.g., "_Z4blahRSt6vectorIiSaIiEE"). The match is done on substrings: if the _s_y_m parameter is a substring of the function name, it is considered to be a match. For C99 and C++ ex- tended identifiers, the function name must be given in UTF-8, not using universal character names. --ffppaattcchhaabbllee--ffuunnccttiioonn--eennttrryy==_N[[,,_M]] Generate _N NOPs right at the beginning of each function, with the function entry point before the _Mth NOP. If _M is omitted, it de- faults to 0 so the function entry points to the address just at the first NOP. The NOP instructions reserve extra space which can be used to patch in any desired instrumentation at run time, provided that the code segment is writable. The amount of space is control- lable indirectly via the number of NOPs; the NOP instruction used corresponds to the instruction emitted by the internal GCC back-end interface "gen_nop". This behavior is target-specific and may also depend on the architecture variant and/or other compilation op- tions. For run-time identification, the starting addresses of these areas, which correspond to their respective function entries minus _M, are additionally collected in the "__patchable_function_entries" sec- tion of the resulting binary. Note that the value of "__attribute__ ((patchable_function_entry (N,M)))" takes precedence over command-line option --ffppaattcchh-- aabbllee--ffuunnccttiioonn--eennttrryy==NN,,MM. This can be used to increase the area size or to remove it completely on a single function. If "N=0", no pad location is recorded. The NOP instructions are inserted at---and maybe before, depending on _M---the function entry address, even before the prologue. The maximum value of _N and _M is 65535. OOppttiioonnss CCoonnttrroolllliinngg tthhee PPrreepprroocceessssoorr These options control the C preprocessor, which is run on each C source file before actual compilation. If you use the --EE option, nothing is done except preprocessing. Some of these options make sense only together with --EE because they cause the preprocessor output to be unsuitable for actual compilation. In addition to the options listed here, there are a number of options to control search paths for include files documented in DDiirreeccttoorryy OOpp-- ttiioonnss. Options to control preprocessor diagnostics are listed in WWaarrnn-- iinngg OOppttiioonnss. --DD _n_a_m_e Predefine _n_a_m_e as a macro, with definition 1. --DD _n_a_m_e==_d_e_f_i_n_i_t_i_o_n The contents of _d_e_f_i_n_i_t_i_o_n are tokenized and processed as if they appeared during translation phase three in a ##ddeeffiinnee directive. In particular, the definition is truncated by embedded newline charac- ters. If you are invoking the preprocessor from a shell or shell-like program you may need to use the shell's quoting syntax to protect characters such as spaces that have a meaning in the shell syntax. If you wish to define a function-like macro on the command line, write its argument list with surrounding parentheses before the equals sign (if any). Parentheses are meaningful to most shells, so you should quote the option. With sshh and ccsshh, --DD''_n_a_m_e((_a_r_g_s_._._.))==_d_e_f_i_n_i_t_i_o_n'' works. --DD and --UU options are processed in the order they are given on the command line. All --iimmaaccrrooss _f_i_l_e and --iinncclluuddee _f_i_l_e options are pro- cessed after all --DD and --UU options. --UU _n_a_m_e Cancel any previous definition of _n_a_m_e, either built in or provided with a --DD option. --iinncclluuddee _f_i_l_e Process _f_i_l_e as if "#include "file"" appeared as the first line of the primary source file. However, the first directory searched for _f_i_l_e is the preprocessor's working directory _i_n_s_t_e_a_d _o_f the direc- tory containing the main source file. If not found there, it is searched for in the remainder of the "#include "..."" search chain as normal. If multiple --iinncclluuddee options are given, the files are included in the order they appear on the command line. --iimmaaccrrooss _f_i_l_e Exactly like --iinncclluuddee, except that any output produced by scanning _f_i_l_e is thrown away. Macros it defines remain defined. This al- lows you to acquire all the macros from a header without also pro- cessing its declarations. All files specified by --iimmaaccrrooss are processed before all files specified by --iinncclluuddee. --uunnddeeff Do not predefine any system-specific or GCC-specific macros. The standard predefined macros remain defined. --pptthhrreeaadd Define additional macros required for using the POSIX threads li- brary. You should use this option consistently for both compila- tion and linking. This option is supported on GNU/Linux targets, most other Unix derivatives, and also on x86 Cygwin and MinGW tar- gets. --MM Instead of outputting the result of preprocessing, output a rule suitable for mmaakkee describing the dependencies of the main source file. The preprocessor outputs one mmaakkee rule containing the object file name for that source file, a colon, and the names of all the included files, including those coming from --iinncclluuddee or --iimmaaccrrooss command-line options. Unless specified explicitly (with --MMTT or --MMQQ), the object file name consists of the name of the source file with any suffix replaced with object file suffix and with any leading directory parts re- moved. If there are many included files then the rule is split into several lines using \\-newline. The rule has no commands. This option does not suppress the preprocessor's debug output, such as --ddMM. To avoid mixing such debug output with the dependency rules you should explicitly specify the dependency output file with --MMFF, or use an environment variable like DDEEPPEENNDDEENNCCIIEESS__OOUUTTPPUUTT. De- bug output is still sent to the regular output stream as normal. Passing --MM to the driver implies --EE, and suppresses warnings with an implicit --ww. --MMMM Like --MM but do not mention header files that are found in system header directories, nor header files that are included, directly or indirectly, from such a header. This implies that the choice of angle brackets or double quotes in an ##iinncclluuddee directive does not in itself determine whether that header appears in --MMMM dependency output. --MMFF _f_i_l_e When used with --MM or --MMMM, specifies a file to write the dependen- cies to. If no --MMFF switch is given the preprocessor sends the rules to the same place it would send preprocessed output. When used with the driver options --MMDD or --MMMMDD, --MMFF overrides the default dependency output file. If _f_i_l_e is _-, then the dependencies are written to _s_t_d_o_u_t. --MMGG In conjunction with an option such as --MM requesting dependency gen- eration, --MMGG assumes missing header files are generated files and adds them to the dependency list without raising an error. The de- pendency filename is taken directly from the "#include" directive without prepending any path. --MMGG also suppresses preprocessed out- put, as a missing header file renders this useless. This feature is used in automatic updating of makefiles. --MMnnoo--mmoodduulleess Disable dependency generation for compiled module interfaces. --MMPP This option instructs CPP to add a phony target for each dependency other than the main file, causing each to depend on nothing. These dummy rules work around errors mmaakkee gives if you remove header files without updating the _M_a_k_e_f_i_l_e to match. This is typical output: test.o: test.c test.h test.h: --MMTT _t_a_r_g_e_t Change the target of the rule emitted by dependency generation. By default CPP takes the name of the main input file, deletes any di- rectory components and any file suffix such as ..cc, and appends the platform's usual object suffix. The result is the target. An --MMTT option sets the target to be exactly the string you specify. If you want multiple targets, you can specify them as a single ar- gument to --MMTT, or use multiple --MMTT options. For example, --MMTT ''$$((oobbjjppffxx))ffoooo..oo'' might give $(objpfx)foo.o: foo.c --MMQQ _t_a_r_g_e_t Same as --MMTT, but it quotes any characters which are special to Make. --MMQQ ''$$((oobbjjppffxx))ffoooo..oo'' gives $$(objpfx)foo.o: foo.c The default target is automatically quoted, as if it were given with --MMQQ. --MMDD --MMDD is equivalent to --MM --MMFF _f_i_l_e, except that --EE is not implied. The driver determines _f_i_l_e based on whether an --oo option is given. If it is, the driver uses its argument but with a suffix of _._d, otherwise it takes the name of the input file, removes any direc- tory components and suffix, and applies a _._d suffix. If --MMDD is used in conjunction with --EE, any --oo switch is understood to specify the dependency output file, but if used without --EE, each --oo is understood to specify a target object file. Since --EE is not implied, --MMDD can be used to generate a dependency output file as a side effect of the compilation process. --MMMMDD Like --MMDD except mention only user header files, not system header files. --ffpprreepprroocceesssseedd Indicate to the preprocessor that the input file has already been preprocessed. This suppresses things like macro expansion, tri- graph conversion, escaped newline splicing, and processing of most directives. The preprocessor still recognizes and removes com- ments, so that you can pass a file preprocessed with --CC to the com- piler without problems. In this mode the integrated preprocessor is little more than a tokenizer for the front ends. --ffpprreepprroocceesssseedd is implicit if the input file has one of the exten- sions ..ii, ..iiii or ..mmii. These are the extensions that GCC uses for preprocessed files created by --ssaavvee--tteemmppss. --ffddiirreeccttiivveess--oonnllyy When preprocessing, handle directives, but do not expand macros. The option's behavior depends on the --EE and --ffpprreepprroocceesssseedd options. With --EE, preprocessing is limited to the handling of directives such as "#define", "#ifdef", and "#error". Other preprocessor op- erations, such as macro expansion and trigraph conversion are not performed. In addition, the --ddDD option is implicitly enabled. With --ffpprreepprroocceesssseedd, predefinition of command line and most builtin macros is disabled. Macros such as "__LINE__", which are contextu- ally dependent, are handled normally. This enables compilation of files previously preprocessed with "-E -fdirectives-only". With both --EE and --ffpprreepprroocceesssseedd, the rules for --ffpprreepprroocceesssseedd take precedence. This enables full preprocessing of files previously preprocessed with "-E -fdirectives-only". --ffddoollllaarrss--iinn--iiddeennttiiffiieerrss Accept $$ in identifiers. --ffeexxtteennddeedd--iiddeennttiiffiieerrss Accept universal character names and extended characters in identi- fiers. This option is enabled by default for C99 (and later C standard versions) and C++. --ffnnoo--ccaannoonniiccaall--ssyysstteemm--hheeaaddeerrss When preprocessing, do not shorten system header paths with canoni- calization. --ffmmaaxx--iinncclluuddee--ddeepptthh==_d_e_p_t_h Set the maximum depth of the nested #include. The default is 200. --ffttaabbssttoopp==_w_i_d_t_h Set the distance between tab stops. This helps the preprocessor report correct column numbers in warnings or errors, even if tabs appear on the line. If the value is less than 1 or greater than 100, the option is ignored. The default is 8. --ffttrraacckk--mmaaccrroo--eexxppaannssiioonn[==_l_e_v_e_l] Track locations of tokens across macro expansions. This allows the compiler to emit diagnostic about the current macro expansion stack when a compilation error occurs in a macro expansion. Using this option makes the preprocessor and the compiler consume more memory. The _l_e_v_e_l parameter can be used to choose the level of precision of token location tracking thus decreasing the memory consumption if necessary. Value 00 of _l_e_v_e_l de-activates this option. Value 11 tracks tokens locations in a degraded mode for the sake of minimal memory overhead. In this mode all tokens resulting from the expan- sion of an argument of a function-like macro have the same loca- tion. Value 22 tracks tokens locations completely. This value is the most memory hungry. When this option is given no argument, the de- fault parameter value is 22. Note that "-ftrack-macro-expansion=2" is activated by default. --ffmmaaccrroo--pprreeffiixx--mmaapp==_o_l_d==_n_e_w When preprocessing files residing in directory _o_l_d, expand the "__FILE__" and "__BASE_FILE__" macros as if the files resided in directory _n_e_w instead. This can be used to change an absolute path to a relative path by using _. for _n_e_w which can result in more re- producible builds that are location independent. This option also affects "__builtin_FILE()" during compilation. See also --ffffiillee--pprreeffiixx--mmaapp. --ffeexxeecc--cchhaarrsseett==_c_h_a_r_s_e_t Set the execution character set, used for string and character con- stants. The default is UTF-8. _c_h_a_r_s_e_t can be any encoding sup- ported by the system's "iconv" library routine. --ffwwiiddee--eexxeecc--cchhaarrsseett==_c_h_a_r_s_e_t Set the wide execution character set, used for wide string and character constants. The default is UTF-32 or UTF-16, whichever corresponds to the width of "wchar_t". As with --ffeexxeecc--cchhaarrsseett, _c_h_a_r_s_e_t can be any encoding supported by the system's "iconv" li- brary routine; however, you will have problems with encodings that do not fit exactly in "wchar_t". --ffiinnppuutt--cchhaarrsseett==_c_h_a_r_s_e_t Set the input character set, used for translation from the charac- ter set of the input file to the source character set used by GCC. If the locale does not specify, or GCC cannot get this information from the locale, the default is UTF-8. This can be overridden by either the locale or this command-line option. Currently the com- mand-line option takes precedence if there's a conflict. _c_h_a_r_s_e_t can be any encoding supported by the system's "iconv" library rou- tine. --ffppcchh--ddeeppss When using precompiled headers, this flag causes the dependency- output flags to also list the files from the precompiled header's dependencies. If not specified, only the precompiled header are listed and not the files that were used to create it, because those files are not consulted when a precompiled header is used. --ffppcchh--pprreepprroocceessss This option allows use of a precompiled header together with --EE. It inserts a special "#pragma", "#pragma GCC pch_preprocess "_f_i_l_e_- _n_a_m_e_"_" in the output to mark the place where the precompiled header was found, and its _f_i_l_e_n_a_m_e. When --ffpprreepprroocceesssseedd is in use, GCC recognizes this "#pragma" and loads the PCH. This option is off by default, because the resulting preprocessed output is only really suitable as input to GCC. It is switched on by --ssaavvee--tteemmppss. You should not write this "#pragma" in your own code, but it is safe to edit the filename if the PCH file is available in a differ- ent location. The filename may be absolute or it may be relative to GCC's current directory. --ffwwoorrkkiinngg--ddiirreeccttoorryy Enable generation of linemarkers in the preprocessor output that let the compiler know the current working directory at the time of preprocessing. When this option is enabled, the preprocessor emits, after the initial linemarker, a second linemarker with the current working directory followed by two slashes. GCC uses this directory, when it's present in the preprocessed input, as the di- rectory emitted as the current working directory in some debugging information formats. This option is implicitly enabled if debug- ging information is enabled, but this can be inhibited with the negated form --ffnnoo--wwoorrkkiinngg--ddiirreeccttoorryy. If the --PP flag is present in the command line, this option has no effect, since no "#line" di- rectives are emitted whatsoever. --AA _p_r_e_d_i_c_a_t_e==_a_n_s_w_e_r Make an assertion with the predicate _p_r_e_d_i_c_a_t_e and answer _a_n_s_w_e_r. This form is preferred to the older form --AA _p_r_e_d_i_c_a_t_e((_a_n_s_w_e_r)), which is still supported, because it does not use shell special characters. --AA --_p_r_e_d_i_c_a_t_e==_a_n_s_w_e_r Cancel an assertion with the predicate _p_r_e_d_i_c_a_t_e and answer _a_n_s_w_e_r. --CC Do not discard comments. All comments are passed through to the output file, except for comments in processed directives, which are deleted along with the directive. You should be prepared for side effects when using --CC; it causes the preprocessor to treat comments as tokens in their own right. For example, comments appearing at the start of what would be a di- rective line have the effect of turning that line into an ordinary source line, since the first token on the line is no longer a ##. --CCCC Do not discard comments, including during macro expansion. This is like --CC, except that comments contained within macros are also passed through to the output file where the macro is expanded. In addition to the side effects of the --CC option, the --CCCC option causes all C++-style comments inside a macro to be converted to C-style comments. This is to prevent later use of that macro from inadvertently commenting out the remainder of the source line. The --CCCC option is generally used to support lint comments. --PP Inhibit generation of linemarkers in the output from the preproces- sor. This might be useful when running the preprocessor on some- thing that is not C code, and will be sent to a program which might be confused by the linemarkers. --ttrraaddiittiioonnaall --ttrraaddiittiioonnaall--ccpppp Try to imitate the behavior of pre-standard C preprocessors, as op- posed to ISO C preprocessors. See the GNU CPP manual for details. Note that GCC does not otherwise attempt to emulate a pre-standard C compiler, and these options are only supported with the --EE switch, or when invoking CPP explicitly. --ttrriiggrraapphhss Support ISO C trigraphs. These are three-character sequences, all starting with ????, that are defined by ISO C to stand for single characters. For example, ????// stands for \\, so ''????//nn'' is a charac- ter constant for a newline. The nine trigraphs and their replacements are Trigraph: ??( ??) ??< ??> ??= ??/ ??' ??! ??- Replacement: [ ] { } # \ ^ | ~ By default, GCC ignores trigraphs, but in standard-conforming modes it converts them. See the --ssttdd and --aannssii options. --rreemmaapp Enable special code to work around file systems which only permit very short file names, such as MS-DOS. --HH Print the name of each header file used, in addition to other nor- mal activities. Each name is indented to show how deep in the ##iinn-- cclluuddee stack it is. Precompiled header files are also printed, even if they are found to be invalid; an invalid precompiled header file is printed with ......xx and a valid one with ......!! . --dd_l_e_t_t_e_r_s Says to make debugging dumps during compilation as specified by _l_e_t_t_e_r_s. The flags documented here are those relevant to the pre- processor. Other _l_e_t_t_e_r_s are interpreted by the compiler proper, or reserved for future versions of GCC, and so are silently ig- nored. If you specify _l_e_t_t_e_r_s whose behavior conflicts, the result is undefined. --ddMM Instead of the normal output, generate a list of ##ddeeffiinnee direc- tives for all the macros defined during the execution of the preprocessor, including predefined macros. This gives you a way of finding out what is predefined in your version of the preprocessor. Assuming you have no file _f_o_o_._h, the command touch foo.h; cpp -dM foo.h shows all the predefined macros. If you use --ddMM without the --EE option, --ddMM is interpreted as a synonym for --ffdduummpp--rrttll--mmaacchh. --ddDD Like --ddMM except in two respects: it does _n_o_t include the prede- fined macros, and it outputs _b_o_t_h the ##ddeeffiinnee directives and the result of preprocessing. Both kinds of output go to the standard output file. --ddNN Like --ddDD, but emit only the macro names, not their expansions. --ddII Output ##iinncclluuddee directives in addition to the result of prepro- cessing. --ddUU Like --ddDD except that only macros that are expanded, or whose definedness is tested in preprocessor directives, are output; the output is delayed until the use or test of the macro; and ##uunnddeeff directives are also output for macros tested but unde- fined at the time. --ffddeebbuugg--ccpppp This option is only useful for debugging GCC. When used from CPP or with --EE, it dumps debugging information about location maps. Every token in the output is preceded by the dump of the map its location belongs to. When used from GCC without --EE, this option has no effect. --WWpp,,_o_p_t_i_o_n You can use --WWpp,,_o_p_t_i_o_n to bypass the compiler driver and pass _o_p_- _t_i_o_n directly through to the preprocessor. If _o_p_t_i_o_n contains com- mas, it is split into multiple options at the commas. However, many options are modified, translated or interpreted by the com- piler driver before being passed to the preprocessor, and --WWpp forcibly bypasses this phase. The preprocessor's direct interface is undocumented and subject to change, so whenever possible you should avoid using --WWpp and let the driver handle the options in- stead. --XXpprreepprroocceessssoorr _o_p_t_i_o_n Pass _o_p_t_i_o_n as an option to the preprocessor. You can use this to supply system-specific preprocessor options that GCC does not rec- ognize. If you want to pass an option that takes an argument, you must use --XXpprreepprroocceessssoorr twice, once for the option and once for the argu- ment. --nnoo--iinntteeggrraatteedd--ccpppp Perform preprocessing as a separate pass before compilation. By default, GCC performs preprocessing as an integrated part of input tokenization and parsing. If this option is provided, the appro- priate language front end (cccc11, cccc11pplluuss, or cccc11oobbjj for C, C++, and Objective-C, respectively) is instead invoked twice, once for pre- processing only and once for actual compilation of the preprocessed input. This option may be useful in conjunction with the --BB or --wwrraappppeerr options to specify an alternate preprocessor or perform additional processing of the program source between normal prepro- cessing and compilation. --ffllaarrggee--ssoouurrccee--ffiilleess Adjust GCC to expect large source files, at the expense of slower compilation and higher memory usage. Specifically, GCC normally tracks both column numbers and line num- bers within source files and it normally prints both of these num- bers in diagnostics. However, once it has processed a certain num- ber of source lines, it stops tracking column numbers and only tracks line numbers. This means that diagnostics for later lines do not include column numbers. It also means that options like --WWmmiisslleeaaddiinngg--iinnddeennttaattiioonn cease to work at that point, although the compiler prints a note if this happens. Passing --ffllaarrggee--ssoouurrccee--ffiilleess significantly increases the number of source lines that GCC can process before it stops tracking columns. PPaassssiinngg OOppttiioonnss ttoo tthhee AAsssseemmbblleerr You can pass options to the assembler. --WWaa,,_o_p_t_i_o_n Pass _o_p_t_i_o_n as an option to the assembler. If _o_p_t_i_o_n contains com- mas, it is split into multiple options at the commas. --XXaasssseemmbblleerr _o_p_t_i_o_n Pass _o_p_t_i_o_n as an option to the assembler. You can use this to supply system-specific assembler options that GCC does not recog- nize. If you want to pass an option that takes an argument, you must use --XXaasssseemmbblleerr twice, once for the option and once for the argument. OOppttiioonnss ffoorr LLiinnkkiinngg These options come into play when the compiler links object files into an executable output file. They are meaningless if the compiler is not doing a link step. _o_b_j_e_c_t_-_f_i_l_e_-_n_a_m_e A file name that does not end in a special recognized suffix is considered to name an object file or library. (Object files are distinguished from libraries by the linker according to the file contents.) If linking is done, these object files are used as in- put to the linker. --cc --SS --EE If any of these options is used, then the linker is not run, and object file names should not be used as arguments. --fflliinnkkeerr--oouuttppuutt==_t_y_p_e This option controls code generation of the link-time optimizer. By default the linker output is automatically determined by the linker plugin. For debugging the compiler and if incremental link- ing with a non-LTO object file is desired, it may be useful to con- trol the type manually. If _t_y_p_e is eexxeecc, code generation produces a static binary. In this case --ffppiicc and --ffppiiee are both disabled. If _t_y_p_e is ddyynn, code generation produces a shared library. In this case --ffppiicc or --ffPPIICC is preserved, but not enabled automatically. This allows to build shared libraries without position-independent code on architectures where this is possible, i.e. on x86. If _t_y_p_e is ppiiee, code generation produces an --ffppiiee executable. This results in similar optimizations as eexxeecc except that --ffppiiee is not disabled if specified at compilation time. If _t_y_p_e is rreell, the compiler assumes that incremental linking is done. The sections containing intermediate code for link-time op- timization are merged, pre-optimized, and output to the resulting object file. In addition, if --ffffaatt--llttoo--oobbjjeeccttss is specified, binary code is produced for future non-LTO linking. The object file pro- duced by incremental linking is smaller than a static library pro- duced from the same object files. At link time the result of in- cremental linking also loads faster than a static library assuming that the majority of objects in the library are used. Finally nnoollttoo--rreell configures the compiler for incremental linking where code generation is forced, a final binary is produced, and the intermediate code for later link-time optimization is stripped. When multiple object files are linked together the resulting code is better optimized than with link-time optimizations disabled (for example, cross-module inlining happens), but most of benefits of whole program optimizations are lost. During the incremental link (by --rr) the linker plugin defaults to rreell. With current interfaces to GNU Binutils it is however not pos- sible to incrementally link LTO objects and non-LTO objects into a single mixed object file. If any of object files in incremental link cannot be used for link-time optimization, the linker plugin issues a warning and uses nnoollttoo--rreell. To maintain whole program op- timization, it is recommended to link such objects into static li- brary instead. Alternatively it is possible to use H.J. Lu's binu- tils with support for mixed objects. --ffuussee--lldd==bbffdd Use the bbffdd linker instead of the default linker. --ffuussee--lldd==ggoolldd Use the ggoolldd linker instead of the default linker. --ffuussee--lldd==lllldd Use the LLVM lllldd linker instead of the default linker. --ffuussee--lldd==mmoolldd Use the Modern Linker (mmoolldd) instead of the default linker. --ll_l_i_b_r_a_r_y --ll _l_i_b_r_a_r_y Search the library named _l_i_b_r_a_r_y when linking. (The second alter- native with the library as a separate argument is only for POSIX compliance and is not recommended.) The --ll option is passed directly to the linker by GCC. Refer to your linker documentation for exact details. The general descrip- tion below applies to the GNU linker. The linker searches a standard list of directories for the library. The directories searched include several standard system directo- ries plus any that you specify with --LL. Static libraries are archives of object files, and have file names like _l_i_b_l_i_b_r_a_r_y_._a. Some targets also support shared libraries, which typically have names like _l_i_b_l_i_b_r_a_r_y_._s_o. If both static and shared libraries are found, the linker gives preference to linking with the shared library unless the --ssttaattiicc option is used. It makes a difference where in the command you write this option; the linker searches and processes libraries and object files in the order they are specified. Thus, ffoooo..oo --llzz bbaarr..oo searches library zz after file _f_o_o_._o but before _b_a_r_._o. If _b_a_r_._o refers to functions in zz, those functions may not be loaded. --lloobbjjcc You need this special case of the --ll option in order to link an Ob- jective-C or Objective-C++ program. --nnoossttaarrttffiilleess Do not use the standard system startup files when linking. The standard system libraries are used normally, unless --nnoossttddlliibb, --nnoo-- lliibbcc, or --nnooddeeffaauullttlliibbss is used. --nnooddeeffaauullttlliibbss Do not use the standard system libraries when linking. Only the libraries you specify are passed to the linker, and options speci- fying linkage of the system libraries, such as --ssttaattiicc--lliibbggcccc or --sshhaarreedd--lliibbggcccc, are ignored. The standard startup files are used normally, unless --nnoossttaarrttffiilleess is used. The compiler may generate calls to "memcmp", "memset", "memcpy" and "memmove". These entries are usually resolved by entries in libc. These entry points should be supplied through some other mechanism when this option is specified. --nnoolliibbcc Do not use the C library or system libraries tightly coupled with it when linking. Still link with the startup files, _l_i_b_g_c_c or toolchain provided language support libraries such as _l_i_b_g_n_a_t, _l_i_b_g_f_o_r_t_r_a_n or _l_i_b_s_t_d_c_+_+ unless options preventing their inclusion are used as well. This typically removes --llcc from the link command line, as well as system libraries that normally go with it and be- come meaningless when absence of a C library is assumed, for exam- ple --llpptthhrreeaadd or --llmm in some configurations. This is intended for bare-board targets when there is indeed no C library available. --nnoossttddlliibb Do not use the standard system startup files or libraries when linking. No startup files and only the libraries you specify are passed to the linker, and options specifying linkage of the system libraries, such as --ssttaattiicc--lliibbggcccc or --sshhaarreedd--lliibbggcccc, are ignored. The compiler may generate calls to "memcmp", "memset", "memcpy" and "memmove". These entries are usually resolved by entries in libc. These entry points should be supplied through some other mechanism when this option is specified. One of the standard libraries bypassed by --nnoossttddlliibb and --nnooddeeffaauulltt-- lliibbss is _l_i_b_g_c_c_._a, a library of internal subroutines which GCC uses to overcome shortcomings of particular machines, or special needs for some languages. In most cases, you need _l_i_b_g_c_c_._a even when you want to avoid other standard libraries. In other words, when you specify --nnoossttddlliibb or --nnooddeeffaauullttlliibbss you should usually specify --llggcccc as well. This en- sures that you have no unresolved references to internal GCC li- brary subroutines. (An example of such an internal subroutine is "__main", used to ensure C++ constructors are called.) --ee _e_n_t_r_y ----eennttrryy==_e_n_t_r_y Specify that the program entry point is _e_n_t_r_y. The argument is in- terpreted by the linker; the GNU linker accepts either a symbol name or an address. --ppiiee Produce a dynamically linked position independent executable on targets that support it. For predictable results, you must also specify the same set of options used for compilation (--ffppiiee, --ffPPIIEE, or model suboptions) when you specify this linker option. --nnoo--ppiiee Don't produce a dynamically linked position independent executable. --ssttaattiicc--ppiiee Produce a static position independent executable on targets that support it. A static position independent executable is similar to a static executable, but can be loaded at any address without a dy- namic linker. For predictable results, you must also specify the same set of options used for compilation (--ffppiiee, --ffPPIIEE, or model suboptions) when you specify this linker option. --pptthhrreeaadd Link with the POSIX threads library. This option is supported on GNU/Linux targets, most other Unix derivatives, and also on x86 Cygwin and MinGW targets. On some targets this option also sets flags for the preprocessor, so it should be used consistently for both compilation and linking. --rr Produce a relocatable object as output. This is also known as par- tial linking. --rrddyynnaammiicc Pass the flag --eexxppoorrtt--ddyynnaammiicc to the ELF linker, on targets that support it. This instructs the linker to add all symbols, not only used ones, to the dynamic symbol table. This option is needed for some uses of "dlopen" or to allow obtaining backtraces from within a program. --ss Remove all symbol table and relocation information from the exe- cutable. --ssttaattiicc On systems that support dynamic linking, this overrides --ppiiee and prevents linking with the shared libraries. On other systems, this option has no effect. --sshhaarreedd Produce a shared object which can then be linked with other objects to form an executable. Not all systems support this option. For predictable results, you must also specify the same set of options used for compilation (--ffppiicc, --ffPPIICC, or model suboptions) when you specify this linker option.[1] --sshhaarreedd--lliibbggcccc --ssttaattiicc--lliibbggcccc On systems that provide _l_i_b_g_c_c as a shared library, these options force the use of either the shared or static version, respectively. If no shared version of _l_i_b_g_c_c was built when the compiler was con- figured, these options have no effect. There are several situations in which an application should use the shared _l_i_b_g_c_c instead of the static version. The most common of these is when the application wishes to throw and catch exceptions across different shared libraries. In that case, each of the li- braries as well as the application itself should use the shared _l_i_b_g_c_c. Therefore, the G++ driver automatically adds --sshhaarreedd--lliibbggcccc when- ever you build a shared library or a main executable, because C++ programs typically use exceptions, so this is the right thing to do. If, instead, you use the GCC driver to create shared libraries, you may find that they are not always linked with the shared _l_i_b_g_c_c. If GCC finds, at its configuration time, that you have a non-GNU linker or a GNU linker that does not support option ----eehh--ffrraammee--hhddrr, it links the shared version of _l_i_b_g_c_c into shared libraries by de- fault. Otherwise, it takes advantage of the linker and optimizes away the linking with the shared version of _l_i_b_g_c_c, linking with the static version of libgcc by default. This allows exceptions to propagate through such shared libraries, without incurring reloca- tion costs at library load time. However, if a library or main executable is supposed to throw or catch exceptions, you must link it using the G++ driver, or using the option --sshhaarreedd--lliibbggcccc, such that it is linked with the shared _l_i_b_g_c_c. --ssttaattiicc--lliibbaassaann When the --ffssaanniittiizzee==aaddddrreessss option is used to link a program, the GCC driver automatically links against lliibbaassaann. If _l_i_b_a_s_a_n is available as a shared library, and the --ssttaattiicc option is not used, then this links against the shared version of _l_i_b_a_s_a_n. The --ssttaattiicc--lliibbaassaann option directs the GCC driver to link _l_i_b_a_s_a_n stat- ically, without necessarily linking other libraries statically. --ssttaattiicc--lliibbttssaann When the --ffssaanniittiizzee==tthhrreeaadd option is used to link a program, the GCC driver automatically links against lliibbttssaann. If _l_i_b_t_s_a_n is available as a shared library, and the --ssttaattiicc option is not used, then this links against the shared version of _l_i_b_t_s_a_n. The --ssttaattiicc--lliibbttssaann option directs the GCC driver to link _l_i_b_t_s_a_n stat- ically, without necessarily linking other libraries statically. --ssttaattiicc--lliibbllssaann When the --ffssaanniittiizzee==lleeaakk option is used to link a program, the GCC driver automatically links against lliibbllssaann. If _l_i_b_l_s_a_n is avail- able as a shared library, and the --ssttaattiicc option is not used, then this links against the shared version of _l_i_b_l_s_a_n. The --ssttaattiicc--llii-- bbllssaann option directs the GCC driver to link _l_i_b_l_s_a_n statically, without necessarily linking other libraries statically. --ssttaattiicc--lliibbuubbssaann When the --ffssaanniittiizzee==uunnddeeffiinneedd option is used to link a program, the GCC driver automatically links against lliibbuubbssaann. If _l_i_b_u_b_s_a_n is available as a shared library, and the --ssttaattiicc option is not used, then this links against the shared version of _l_i_b_u_b_s_a_n. The --ssttaattiicc--lliibbuubbssaann option directs the GCC driver to link _l_i_b_u_b_s_a_n statically, without necessarily linking other libraries statically. --ssttaattiicc--lliibbssttddcc++++ When the gg++++ program is used to link a C++ program, it normally au- tomatically links against lliibbssttddcc++++. If _l_i_b_s_t_d_c_+_+ is available as a shared library, and the --ssttaattiicc option is not used, then this links against the shared version of _l_i_b_s_t_d_c_+_+. That is normally fine. However, it is sometimes useful to freeze the version of _l_i_b_s_t_d_c_+_+ used by the program without going all the way to a fully static link. The --ssttaattiicc--lliibbssttddcc++++ option directs the gg++++ driver to link _l_i_b_s_t_d_c_+_+ statically, without necessarily linking other li- braries statically. --ssyymmbboolliicc Bind references to global symbols when building a shared object. Warn about any unresolved references (unless overridden by the link editor option --XXlliinnkkeerr --zz --XXlliinnkkeerr ddeeffss). Only a few systems sup- port this option. --TT _s_c_r_i_p_t Use _s_c_r_i_p_t as the linker script. This option is supported by most systems using the GNU linker. On some targets, such as bare-board targets without an operating system, the --TT option may be required when linking to avoid references to undefined symbols. --XXlliinnkkeerr _o_p_t_i_o_n Pass _o_p_t_i_o_n as an option to the linker. You can use this to supply system-specific linker options that GCC does not recognize. If you want to pass an option that takes a separate argument, you must use --XXlliinnkkeerr twice, once for the option and once for the argu- ment. For example, to pass --aasssseerrtt ddeeffiinniittiioonnss, you must write --XXlliinnkkeerr --aasssseerrtt --XXlliinnkkeerr ddeeffiinniittiioonnss. It does not work to write --XXlliinnkkeerr ""--aasssseerrtt ddeeffiinniittiioonnss"", because this passes the entire string as a single argument, which is not what the linker expects. When using the GNU linker, it is usually more convenient to pass arguments to linker options using the _o_p_t_i_o_n==_v_a_l_u_e syntax than as separate arguments. For example, you can specify --XXlliinnkkeerr --MMaapp==oouuttppuutt..mmaapp rather than --XXlliinnkkeerr --MMaapp --XXlliinnkkeerr oouuttppuutt..mmaapp. Other linkers may not support this syntax for command-line options. --WWll,,_o_p_t_i_o_n Pass _o_p_t_i_o_n as an option to the linker. If _o_p_t_i_o_n contains commas, it is split into multiple options at the commas. You can use this syntax to pass an argument to the option. For example, --WWll,,--MMaapp,,oouuttppuutt..mmaapp passes --MMaapp oouuttppuutt..mmaapp to the linker. When us- ing the GNU linker, you can also get the same effect with --WWll,,--MMaapp==oouuttppuutt..mmaapp. --uu _s_y_m_b_o_l Pretend the symbol _s_y_m_b_o_l is undefined, to force linking of library modules to define it. You can use --uu multiple times with different symbols to force loading of additional library modules. --zz _k_e_y_w_o_r_d --zz is passed directly on to the linker along with the keyword _k_e_y_- _w_o_r_d. See the section in the documentation of your linker for per- mitted values and their meanings. OOppttiioonnss ffoorr DDiirreeccttoorryy SSeeaarrcchh These options specify directories to search for header files, for li- braries and for parts of the compiler: --II _d_i_r --iiqquuoottee _d_i_r --iissyysstteemm _d_i_r --iiddiirraafftteerr _d_i_r Add the directory _d_i_r to the list of directories to be searched for header files during preprocessing. If _d_i_r begins with == or $SYS- ROOT, then the == or $SYSROOT is replaced by the sysroot prefix; see ----ssyyssrroooott and --iissyyssrroooott. Directories specified with --iiqquuoottee apply only to the quote form of the directive, "#include "_f_i_l_e_"_". Directories specified with --II, --iissyysstteemm, or --iiddiirraafftteerr apply to lookup for both the "#in- clude "_f_i_l_e_"_" and "#include <_f_i_l_e_>_" directives. You can specify any number or combination of these options on the command line to search for header files in several directories. The lookup order is as follows: 1. For the quote form of the include directive, the directory of the current file is searched first. 2. For the quote form of the include directive, the directories specified by --iiqquuoottee options are searched in left-to-right or- der, as they appear on the command line. 3. Directories specified with --II options are scanned in left-to- right order. 4. Directories specified with --iissyysstteemm options are scanned in left-to-right order. 5. Standard system directories are scanned. 6. Directories specified with --iiddiirraafftteerr options are scanned in left-to-right order. You can use --II to override a system header file, substituting your own version, since these directories are searched before the stan- dard system header file directories. However, you should not use this option to add directories that contain vendor-supplied system header files; use --iissyysstteemm for that. The --iissyysstteemm and --iiddiirraafftteerr options also mark the directory as a system directory, so that it gets the same special treatment that is applied to the standard system directories. If a standard system include directory, or a directory specified with --iissyysstteemm, is also specified with --II, the --II option is ignored. The directory is still searched but as a system directory at its normal position in the system include chain. This is to ensure that GCC's procedure to fix buggy system headers and the ordering for the "#include_next" directive are not inadvertently changed. If you really need to change the search order for system directo- ries, use the --nnoossttddiinncc and/or --iissyysstteemm options. --II-- Split the include path. This option has been deprecated. Please use --iiqquuoottee instead for --II directories before the --II-- and remove the --II-- option. Any directories specified with --II options before --II-- are searched only for headers requested with "#include "_f_i_l_e_"_"; they are not searched for "#include <_f_i_l_e_>_". If additional directories are specified with --II options after the --II--, those directories are searched for all ##iinncclluuddee directives. In addition, --II-- inhibits the use of the directory of the current file directory as the first search directory for "#include "_f_i_l_e_"_". There is no way to override this effect of --II--. --iipprreeffiixx _p_r_e_f_i_x Specify _p_r_e_f_i_x as the prefix for subsequent --iiwwiitthhpprreeffiixx options. If the prefix represents a directory, you should include the final //. --iiwwiitthhpprreeffiixx _d_i_r --iiwwiitthhpprreeffiixxbbeeffoorree _d_i_r Append _d_i_r to the prefix specified previously with --iipprreeffiixx, and add the resulting directory to the include search path. --iiwwiitthhpprree-- ffiixxbbeeffoorree puts it in the same place --II would; --iiwwiitthhpprreeffiixx puts it where --iiddiirraafftteerr would. --iissyyssrroooott _d_i_r This option is like the ----ssyyssrroooott option, but applies only to header files (except for Darwin targets, where it applies to both header files and libraries). See the ----ssyyssrroooott option for more in- formation. --iimmuullttiilliibb _d_i_r Use _d_i_r as a subdirectory of the directory containing target-spe- cific C++ headers. --nnoossttddiinncc Do not search the standard system directories for header files. Only the directories explicitly specified with --II, --iiqquuoottee, --iissyyss-- tteemm, and/or --iiddiirraafftteerr options (and the directory of the current file, if appropriate) are searched. --nnoossttddiinncc++++ Do not search for header files in the C++-specific standard direc- tories, but do still search the other standard directories. (This option is used when building the C++ library.) --iipplluuggiinnddiirr==_d_i_r Set the directory to search for plugins that are passed by --ffpplluu-- ggiinn==_n_a_m_e instead of --ffpplluuggiinn==_p_a_t_h//_n_a_m_e..ssoo. This option is not meant to be used by the user, but only passed by the driver. --LL_d_i_r Add directory _d_i_r to the list of directories to be searched for --ll. --BB_p_r_e_f_i_x This option specifies where to find the executables, libraries, in- clude files, and data files of the compiler itself. The compiler driver program runs one or more of the subprograms ccpppp, cccc11, aass and lldd. It tries _p_r_e_f_i_x as a prefix for each program it tries to run, both with and without _m_a_c_h_i_n_e//_v_e_r_s_i_o_n// for the corresponding target machine and compiler version. For each subprogram to be run, the compiler driver first tries the --BB prefix, if any. If that name is not found, or if --BB is not specified, the driver tries two standard prefixes, _/_u_s_r_/_l_i_b_/_g_c_c_/ and _/_u_s_r_/_l_o_c_a_l_/_l_i_b_/_g_c_c_/. If neither of those results in a file name that is found, the unmodified program name is searched for us- ing the directories specified in your PPAATTHH environment variable. The compiler checks to see if the path provided by --BB refers to a directory, and if necessary it adds a directory separator character at the end of the path. --BB prefixes that effectively specify directory names also apply to libraries in the linker, because the compiler translates these op- tions into --LL options for the linker. They also apply to include files in the preprocessor, because the compiler translates these options into --iissyysstteemm options for the preprocessor. In this case, the compiler appends iinncclluuddee to the prefix. The runtime support file _l_i_b_g_c_c_._a can also be searched for using the --BB prefix, if needed. If it is not found there, the two stan- dard prefixes above are tried, and that is all. The file is left out of the link if it is not found by those means. Another way to specify a prefix much like the --BB prefix is to use the environment variable GGCCCC__EEXXEECC__PPRREEFFIIXX. As a special kludge, if the path provided by --BB is _[_d_i_r_/_]_s_t_a_g_e_N_/, where _N is a number in the range 0 to 9, then it is replaced by _[_d_i_r_/_]_i_n_c_l_u_d_e. This is to help with boot-strapping the compiler. --nnoo--ccaannoonniiccaall--pprreeffiixxeess Do not expand any symbolic links, resolve references to //....// or //..//, or make the path absolute when generating a relative prefix. ----ssyyssrroooott==_d_i_r Use _d_i_r as the logical root directory for headers and libraries. For example, if the compiler normally searches for headers in _/_u_s_r_/_i_n_c_l_u_d_e and libraries in _/_u_s_r_/_l_i_b, it instead searches _d_i_r_/_u_s_r_/_i_n_c_l_u_d_e and _d_i_r_/_u_s_r_/_l_i_b. If you use both this option and the --iissyyssrroooott option, then the ----ssyyssrroooott option applies to libraries, but the --iissyyssrroooott option ap- plies to header files. The GNU linker (beginning with version 2.16) has the necessary sup- port for this option. If your linker does not support this option, the header file aspect of ----ssyyssrroooott still works, but the library aspect does not. ----nnoo--ssyyssrroooott--ssuuffffiixx For some targets, a suffix is added to the root directory specified with ----ssyyssrroooott, depending on the other options used, so that head- ers may for example be found in _d_i_r_/_s_u_f_f_i_x_/_u_s_r_/_i_n_c_l_u_d_e instead of _d_i_r_/_u_s_r_/_i_n_c_l_u_d_e. This option disables the addition of such a suf- fix. OOppttiioonnss ffoorr CCooddee GGeenneerraattiioonn CCoonnvveennttiioonnss These machine-independent options control the interface conventions used in code generation. Most of them have both positive and negative forms; the negative form of --ffffoooo is --ffnnoo--ffoooo. In the table below, only one of the forms is listed---the one that is not the default. You can figure out the other form by either removing nnoo-- or adding it. --ffssttaacckk--rreeuussee==_r_e_u_s_e_-_l_e_v_e_l This option controls stack space reuse for user declared local/auto variables and compiler generated temporaries. _r_e_u_s_e___l_e_v_e_l can be aallll, nnaammeedd__vvaarrss, or nnoonnee. aallll enables stack reuse for all local variables and temporaries, nnaammeedd__vvaarrss enables the reuse only for user defined local variables with names, and nnoonnee disables stack reuse completely. The default value is aallll. The option is needed when the program extends the lifetime of a scoped local variable or a compiler generated temporary beyond the end point defined by the language. When a lifetime of a variable ends, and if the variable lives in memory, the optimizing compiler has the freedom to reuse its stack space with other temporaries or scoped local variables whose live range does not overlap with it. Legacy code extending local lifetime is likely to break with the stack reuse optimiza- tion. For example, int *p; { int local1; p = &local1; local1 = 10; .... } { int local2; local2 = 20; ... } if (*p == 10) // out of scope use of local1 { } Another example: struct A { A(int k) : i(k), j(k) { } int i; int j; }; A *ap; void foo(const A& ar) { ap = &ar; } void bar() { foo(A(10)); // temp object's lifetime ends when foo returns { A a(20); .... } ap->i+= 10; // ap references out of scope temp whose space // is reused with a. What is the value of ap->i? } The lifetime of a compiler generated temporary is well defined by the C++ standard. When a lifetime of a temporary ends, and if the temporary lives in memory, the optimizing compiler has the freedom to reuse its stack space with other temporaries or scoped local variables whose live range does not overlap with it. However some of the legacy code relies on the behavior of older compilers in which temporaries' stack space is not reused, the aggressive stack reuse can lead to runtime errors. This option is used to control the temporary stack reuse optimization. --ffttrraappvv This option generates traps for signed overflow on addition, sub- traction, multiplication operations. The options --ffttrraappvv and --ffwwrraappvv override each other, so using --ffttrraappvv --ffwwrraappvv on the com- mand-line results in --ffwwrraappvv being effective. Note that only ac- tive options override, so using --ffttrraappvv --ffwwrraappvv --ffnnoo--wwrraappvv on the command-line results in --ffttrraappvv being effective. --ffwwrraappvv This option instructs the compiler to assume that signed arithmetic overflow of addition, subtraction and multiplication wraps around using twos-complement representation. This flag enables some opti- mizations and disables others. The options --ffttrraappvv and --ffwwrraappvv override each other, so using --ffttrraappvv --ffwwrraappvv on the command-line results in --ffwwrraappvv being effective. Note that only active options override, so using --ffttrraappvv --ffwwrraappvv --ffnnoo--wwrraappvv on the command-line results in --ffttrraappvv being effective. --ffwwrraappvv--ppooiinntteerr This option instructs the compiler to assume that pointer arith- metic overflow on addition and subtraction wraps around using twos- complement representation. This flag disables some optimizations which assume pointer overflow is invalid. --ffssttrriicctt--oovveerrffllooww This option implies --ffnnoo--wwrraappvv --ffnnoo--wwrraappvv--ppooiinntteerr and when negated implies --ffwwrraappvv --ffwwrraappvv--ppooiinntteerr. --ffeexxcceeppttiioonnss Enable exception handling. Generates extra code needed to propa- gate exceptions. For some targets, this implies GCC generates frame unwind information for all functions, which can produce sig- nificant data size overhead, although it does not affect execution. If you do not specify this option, GCC enables it by default for languages like C++ that normally require exception handling, and disables it for languages like C that do not normally require it. However, you may need to enable this option when compiling C code that needs to interoperate properly with exception handlers written in C++. You may also wish to disable this option if you are com- piling older C++ programs that don't use exception handling. --ffnnoonn--ccaallll--eexxcceeppttiioonnss Generate code that allows trapping instructions to throw excep- tions. Note that this requires platform-specific runtime support that does not exist everywhere. Moreover, it only allows _t_r_a_p_p_i_n_g instructions to throw exceptions, i.e. memory references or float- ing-point instructions. It does not allow exceptions to be thrown from arbitrary signal handlers such as "SIGALRM". This enables --ffeexxcceeppttiioonnss. --ffddeelleettee--ddeeaadd--eexxcceeppttiioonnss Consider that instructions that may throw exceptions but don't oth- erwise contribute to the execution of the program can be optimized away. This does not affect calls to functions except those with the "pure" or "const" attributes. This option is enabled by de- fault for the Ada and C++ compilers, as permitted by the language specifications. Optimization passes that cause dead exceptions to be removed are enabled independently at different optimization lev- els. --ffuunnwwiinndd--ttaabblleess Similar to --ffeexxcceeppttiioonnss, except that it just generates any needed static data, but does not affect the generated code in any other way. You normally do not need to enable this option; instead, a language processor that needs this handling enables it on your be- half. --ffaassyynncchhrroonnoouuss--uunnwwiinndd--ttaabblleess Generate unwind table in DWARF format, if supported by target ma- chine. The table is exact at each instruction boundary, so it can be used for stack unwinding from asynchronous events (such as de- bugger or garbage collector). --ffnnoo--ggnnuu--uunniiqquuee On systems with recent GNU assembler and C library, the C++ com- piler uses the "STB_GNU_UNIQUE" binding to make sure that defini- tions of template static data members and static local variables in inline functions are unique even in the presence of "RTLD_LOCAL"; this is necessary to avoid problems with a library used by two dif- ferent "RTLD_LOCAL" plugins depending on a definition in one of them and therefore disagreeing with the other one about the binding of the symbol. But this causes "dlclose" to be ignored for af- fected DSOs; if your program relies on reinitialization of a DSO via "dlclose" and "dlopen", you can use --ffnnoo--ggnnuu--uunniiqquuee. --ffppcccc--ssttrruucctt--rreettuurrnn Return "short" "struct" and "union" values in memory like longer ones, rather than in registers. This convention is less efficient, but it has the advantage of allowing intercallability between GCC- compiled files and files compiled with other compilers, particu- larly the Portable C Compiler (pcc). The precise convention for returning structures in memory depends on the target configuration macros. Short structures and unions are those whose size and alignment match that of some integer type. WWaarrnniinngg:: code compiled with the --ffppcccc--ssttrruucctt--rreettuurrnn switch is not binary compatible with code compiled with the --ffrreegg--ssttrruucctt--rreettuurrnn switch. Use it to conform to a non-default application binary in- terface. --ffrreegg--ssttrruucctt--rreettuurrnn Return "struct" and "union" values in registers when possible. This is more efficient for small structures than --ffppcccc--ssttrruucctt--rree-- ttuurrnn. If you specify neither --ffppcccc--ssttrruucctt--rreettuurrnn nor --ffrreegg--ssttrruucctt--rreettuurrnn, GCC defaults to whichever convention is standard for the target. If there is no standard convention, GCC defaults to --ffppcccc--ssttrruucctt--rreettuurrnn, except on targets where GCC is the principal compiler. In those cases, we can choose the standard, and we chose the more efficient register return alternative. WWaarrnniinngg:: code compiled with the --ffrreegg--ssttrruucctt--rreettuurrnn switch is not binary compatible with code compiled with the --ffppcccc--ssttrruucctt--rreettuurrnn switch. Use it to conform to a non-default application binary in- terface. --ffsshhoorrtt--eennuummss Allocate to an "enum" type only as many bytes as it needs for the declared range of possible values. Specifically, the "enum" type is equivalent to the smallest integer type that has enough room. WWaarrnniinngg:: the --ffsshhoorrtt--eennuummss switch causes GCC to generate code that is not binary compatible with code generated without that switch. Use it to conform to a non-default application binary interface. --ffsshhoorrtt--wwcchhaarr Override the underlying type for "wchar_t" to be "short unsigned int" instead of the default for the target. This option is useful for building programs to run under WINE. WWaarrnniinngg:: the --ffsshhoorrtt--wwcchhaarr switch causes GCC to generate code that is not binary compatible with code generated without that switch. Use it to conform to a non-default application binary interface. --ffccoommmmoonn In C code, this option controls the placement of global variables defined without an initializer, known as _t_e_n_t_a_t_i_v_e _d_e_f_i_n_i_t_i_o_n_s in the C standard. Tentative definitions are distinct from declara- tions of a variable with the "extern" keyword, which do not allo- cate storage. The default is --ffnnoo--ccoommmmoonn, which specifies that the compiler places uninitialized global variables in the BSS section of the ob- ject file. This inhibits the merging of tentative definitions by the linker so you get a multiple-definition error if the same vari- able is accidentally defined in more than one compilation unit. The --ffccoommmmoonn places uninitialized global variables in a common block. This allows the linker to resolve all tentative definitions of the same variable in different compilation units to the same ob- ject, or to a non-tentative definition. This behavior is inconsis- tent with C++, and on many targets implies a speed and code size penalty on global variable references. It is mainly useful to en- able legacy code to link without errors. --ffnnoo--iiddeenntt Ignore the "#ident" directive. --ffiinnhhiibbiitt--ssiizzee--ddiirreeccttiivvee Don't output a ".size" assembler directive, or anything else that would cause trouble if the function is split in the middle, and the two halves are placed at locations far apart in memory. This op- tion is used when compiling _c_r_t_s_t_u_f_f_._c; you should not need to use it for anything else. --ffvveerrbboossee--aassmm Put extra commentary information in the generated assembly code to make it more readable. This option is generally only of use to those who actually need to read the generated assembly code (per- haps while debugging the compiler itself). --ffnnoo--vveerrbboossee--aassmm, the default, causes the extra information to be omitted and is useful when comparing two assembler files. The added comments include: * information on the compiler version and command-line options, * the source code lines associated with the assembly instruc- tions, in the form FILENAME:LINENUMBER:CONTENT OF LINE, * hints on which high-level expressions correspond to the various assembly instruction operands. For example, given this C source file: int test (int n) { int i; int total = 0; for (i = 0; i < n; i++) total += i * i; return total; } compiling to (x86_64) assembly via --SS and emitting the result di- rect to stdout via --oo -- gcc -S test.c -fverbose-asm -Os -o - gives output similar to this: .file "test.c" # GNU C11 (GCC) version 7.0.0 20160809 (experimental) (x86_64-pc-linux-gnu) [...snip...] # options passed: [...snip...] .text .globl test .type test, @function test: .LFB0: .cfi_startproc # test.c:4: int total = 0; xorl %eax, %eax # # test.c:6: for (i = 0; i < n; i++) xorl %edx, %edx # i .L2: # test.c:6: for (i = 0; i < n; i++) cmpl %edi, %edx # n, i jge .L5 #, # test.c:7: total += i * i; movl %edx, %ecx # i, tmp92 imull %edx, %ecx # i, tmp92 # test.c:6: for (i = 0; i < n; i++) incl %edx # i # test.c:7: total += i * i; addl %ecx, %eax # tmp92, jmp .L2 # .L5: # test.c:10: } ret .cfi_endproc .LFE0: .size test, .-test .ident "GCC: (GNU) 7.0.0 20160809 (experimental)" .section .note.GNU-stack,"",@progbits The comments are intended for humans rather than machines and hence the precise format of the comments is subject to change. --ffrreeccoorrdd--ggcccc--sswwiittcchheess This switch causes the command line used to invoke the compiler to be recorded into the object file that is being created. This switch is only implemented on some targets and the exact format of the recording is target and binary file format dependent, but it usually takes the form of a section containing ASCII text. This switch is related to the --ffvveerrbboossee--aassmm switch, but that switch only records information in the assembler output file as comments, so it never reaches the object file. See also --ggrreeccoorrdd--ggcccc--sswwiittcchheess for another way of storing compiler options into the object file. --ffppiicc Generate position-independent code (PIC) suitable for use in a shared library, if supported for the target machine. Such code ac- cesses all constant addresses through a global offset table (GOT). The dynamic loader resolves the GOT entries when the program starts (the dynamic loader is not part of GCC; it is part of the operating system). If the GOT size for the linked executable exceeds a ma- chine-specific maximum size, you get an error message from the linker indicating that --ffppiicc does not work; in that case, recompile with --ffPPIICC instead. (These maximums are 8k on the SPARC, 28k on AArch64 and 32k on the m68k and RS/6000. The x86 has no such limit.) Position-independent code requires special support, and therefore works only on certain machines. For the x86, GCC supports PIC for System V but not for the Sun 386i. Code generated for the IBM RS/6000 is always position-independent. When this flag is set, the macros "__pic__" and "__PIC__" are de- fined to 1. --ffPPIICC If supported for the target machine, emit position-independent code, suitable for dynamic linking and avoiding any limit on the size of the global offset table. This option makes a difference on AArch64, m68k, PowerPC and SPARC. Position-independent code requires special support, and therefore works only on certain machines. When this flag is set, the macros "__pic__" and "__PIC__" are de- fined to 2. --ffppiiee --ffPPIIEE These options are similar to --ffppiicc and --ffPPIICC, but the generated po- sition-independent code can be only linked into executables. Usu- ally these options are used to compile code that will be linked us- ing the --ppiiee GCC option. --ffppiiee and --ffPPIIEE both define the macros "__pie__" and "__PIE__". The macros have the value 1 for --ffppiiee and 2 for --ffPPIIEE. --ffnnoo--pplltt Do not use the PLT for external function calls in position-indepen- dent code. Instead, load the callee address at call sites from the GOT and branch to it. This leads to more efficient code by elimi- nating PLT stubs and exposing GOT loads to optimizations. On ar- chitectures such as 32-bit x86 where PLT stubs expect the GOT pointer in a specific register, this gives more register allocation freedom to the compiler. Lazy binding requires use of the PLT; with --ffnnoo--pplltt all external symbols are resolved at load time. Alternatively, the function attribute "noplt" can be used to avoid calls through the PLT for specific external functions. In position-dependent code, a few targets also convert calls to functions that are marked to not use the PLT to use the GOT in- stead. --ffnnoo--jjuummpp--ttaabblleess Do not use jump tables for switch statements even where it would be more efficient than other code generation strategies. This option is of use in conjunction with --ffppiicc or --ffPPIICC for building code that forms part of a dynamic linker and cannot reference the address of a jump table. On some targets, jump tables do not require a GOT and this option is not needed. --ffnnoo--bbiitt--tteessttss Do not use bit tests for switch statements even where it would be more efficient than other code generation strategies. --ffffiixxeedd--_r_e_g Treat the register named _r_e_g as a fixed register; generated code should never refer to it (except perhaps as a stack pointer, frame pointer or in some other fixed role). _r_e_g must be the name of a register. The register names accepted are machine-specific and are defined in the "REGISTER_NAMES" macro in the machine description macro file. This flag does not have a negative form, because it specifies a three-way choice. --ffccaallll--uusseedd--_r_e_g Treat the register named _r_e_g as an allocable register that is clob- bered by function calls. It may be allocated for temporaries or variables that do not live across a call. Functions compiled this way do not save and restore the register _r_e_g. It is an error to use this flag with the frame pointer or stack pointer. Use of this flag for other registers that have fixed per- vasive roles in the machine's execution model produces disastrous results. This flag does not have a negative form, because it specifies a three-way choice. --ffccaallll--ssaavveedd--_r_e_g Treat the register named _r_e_g as an allocable register saved by functions. It may be allocated even for temporaries or variables that live across a call. Functions compiled this way save and re- store the register _r_e_g if they use it. It is an error to use this flag with the frame pointer or stack pointer. Use of this flag for other registers that have fixed per- vasive roles in the machine's execution model produces disastrous results. A different sort of disaster results from the use of this flag for a register in which function values may be returned. This flag does not have a negative form, because it specifies a three-way choice. --ffppaacckk--ssttrruucctt[[==_n]] Without a value specified, pack all structure members together without holes. When a value is specified (which must be a small power of two), pack structure members according to this value, rep- resenting the maximum alignment (that is, objects with default alignment requirements larger than this are output potentially un- aligned at the next fitting location. WWaarrnniinngg:: the --ffppaacckk--ssttrruucctt switch causes GCC to generate code that is not binary compatible with code generated without that switch. Additionally, it makes the code suboptimal. Use it to conform to a non-default application binary interface. --fflleeaaddiinngg--uunnddeerrssccoorree This option and its counterpart, --ffnnoo--lleeaaddiinngg--uunnddeerrssccoorree, forcibly change the way C symbols are represented in the object file. One use is to help link with legacy assembly code. WWaarrnniinngg:: the --fflleeaaddiinngg--uunnddeerrssccoorree switch causes GCC to generate code that is not binary compatible with code generated without that switch. Use it to conform to a non-default application binary in- terface. Not all targets provide complete support for this switch. --ffttllss--mmooddeell==_m_o_d_e_l Alter the thread-local storage model to be used. The _m_o_d_e_l argu- ment should be one of gglloobbaall--ddyynnaammiicc, llooccaall--ddyynnaammiicc, iinniittiiaall--eexxeecc or llooccaall--eexxeecc. Note that the choice is subject to optimization: the compiler may use a more efficient model for symbols not visible outside of the translation unit, or if --ffppiicc is not given on the command line. The default without --ffppiicc is iinniittiiaall--eexxeecc; with --ffppiicc the default is gglloobbaall--ddyynnaammiicc. --ffttrraammppoolliinneess For targets that normally need trampolines for nested functions, always generate them instead of using descriptors. Otherwise, for targets that do not need them, like for example HP-PA or IA-64, do nothing. A trampoline is a small piece of code that is created at run time on the stack when the address of a nested function is taken, and is used to call the nested function indirectly. Therefore, it re- quires the stack to be made executable in order for the program to work properly. --ffnnoo--ttrraammppoolliinneess is enabled by default on a language by language basis to let the compiler avoid generating them, if it computes that this is safe, and replace them with descriptors. Descriptors are made up of data only, but the generated code must be prepared to deal with them. As of this writing, --ffnnoo--ttrraammppoolliinneess is enabled by default only for Ada. Moreover, code compiled with --ffttrraammppoolliinneess and code compiled with --ffnnoo--ttrraammppoolliinneess are not binary compatible if nested functions are present. This option must therefore be used on a program-wide ba- sis and be manipulated with extreme care. For languages other than Ada, the "-ftrampolines" and "-fno-trampo- lines" options currently have no effect, and trampolines are always generated on platforms that need them for nested functions. --ffvviissiibbiilliittyy==[ddeeffaauulltt|iinntteerrnnaall|hhiiddddeenn|pprrootteecctteedd] Set the default ELF image symbol visibility to the specified op- tion---all symbols are marked with this unless overridden within the code. Using this feature can very substantially improve link- ing and load times of shared object libraries, produce more opti- mized code, provide near-perfect API export and prevent symbol clashes. It is ssttrroonnggllyy recommended that you use this in any shared objects you distribute. Despite the nomenclature, ddeeffaauulltt always means public; i.e., avail- able to be linked against from outside the shared object. pprroo-- tteecctteedd and iinntteerrnnaall are pretty useless in real-world usage so the only other commonly used option is hhiiddddeenn. The default if --ffvviissii-- bbiilliittyy isn't specified is ddeeffaauulltt, i.e., make every symbol public. A good explanation of the benefits offered by ensuring ELF symbols have the correct visibility is given by "How To Write Shared Li- braries" by Ulrich Drepper (which can be found at )---however a superior solution made possible by this option to marking things hidden when the de- fault is public is to make the default hidden and mark things pub- lic. This is the norm with DLLs on Windows and with --ffvviissiibbiill-- iittyy==hhiiddddeenn and "__attribute__ ((visibility("default")))" instead of "__declspec(dllexport)" you get almost identical semantics with identical syntax. This is a great boon to those working with cross-platform projects. For those adding visibility support to existing code, you may find "#pragma GCC visibility" of use. This works by you enclosing the declarations you wish to set visibility for with (for example) "#pragma GCC visibility push(hidden)" and "#pragma GCC visibility pop". Bear in mind that symbol visibility should be viewed aass ppaarrtt ooff tthhee AAPPII iinntteerrffaaccee ccoonnttrraacctt and thus all new code should always specify visibility when it is not the default; i.e., declarations only for use within the local DSO should aallwwaayyss be marked explic- itly as hidden as so to avoid PLT indirection overheads---making this abundantly clear also aids readability and self-documentation of the code. Note that due to ISO C++ specification requirements, "operator new" and "operator delete" must always be of default vis- ibility. Be aware that headers from outside your project, in particular sys- tem headers and headers from any other library you use, may not be expecting to be compiled with visibility other than the default. You may need to explicitly say "#pragma GCC visibility push(de- fault)" before including any such headers. "extern" declarations are not affected by --ffvviissiibbiilliittyy, so a lot of code can be recompiled with --ffvviissiibbiilliittyy==hhiiddddeenn with no modifica- tions. However, this means that calls to "extern" functions with no explicit visibility use the PLT, so it is more effective to use "__attribute ((visibility))" and/or "#pragma GCC visibility" to tell the compiler which "extern" declarations should be treated as hidden. Note that --ffvviissiibbiilliittyy does affect C++ vague linkage entities. This means that, for instance, an exception class that is be thrown be- tween DSOs must be explicitly marked with default visibility so that the ttyyppee__iinnffoo nodes are unified between the DSOs. An overview of these techniques, their benefits and how to use them is at . --ffssttrriicctt--vvoollaattiillee--bbiittffiieellddss This option should be used if accesses to volatile bit-fields (or other structure fields, although the compiler usually honors those types anyway) should use a single access of the width of the field's type, aligned to a natural alignment if possible. For ex- ample, targets with memory-mapped peripheral registers might re- quire all such accesses to be 16 bits wide; with this flag you can declare all peripheral bit-fields as "unsigned short" (assuming short is 16 bits on these targets) to force GCC to use 16-bit ac- cesses instead of, perhaps, a more efficient 32-bit access. If this option is disabled, the compiler uses the most efficient instruction. In the previous example, that might be a 32-bit load instruction, even though that accesses bytes that do not contain any portion of the bit-field, or memory-mapped registers unrelated to the one being updated. In some cases, such as when the "packed" attribute is applied to a structure field, it may not be possible to access the field with a single read or write that is correctly aligned for the target ma- chine. In this case GCC falls back to generating multiple accesses rather than code that will fault or truncate the result at run time. Note: Due to restrictions of the C/C++11 memory model, write ac- cesses are not allowed to touch non bit-field members. It is therefore recommended to define all bits of the field's type as bit-field members. The default value of this option is determined by the application binary interface for the target processor. --ffssyynncc--lliibbccaallllss This option controls whether any out-of-line instance of the "__sync" family of functions may be used to implement the C++11 "__atomic" family of functions. The default value of this option is enabled, thus the only useful form of the option is --ffnnoo--ssyynncc--lliibbccaallllss. This option is used in the implementation of the _l_i_b_a_t_o_m_i_c runtime library. GGCCCC DDeevveellooppeerr OOppttiioonnss This section describes command-line options that are primarily of in- terest to GCC developers, including options to support compiler testing and investigation of compiler bugs and compile-time performance prob- lems. This includes options that produce debug dumps at various points in the compilation; that print statistics such as memory use and execu- tion time; and that print information about GCC's configuration, such as where it searches for libraries. You should rarely need to use any of these options for ordinary compilation and linking tasks. Many developer options that cause GCC to dump output to a file take an optional ==_f_i_l_e_n_a_m_e suffix. You can specify ssttddoouutt or -- to dump to stan- dard output, and ssttddeerrrr for standard error. If ==_f_i_l_e_n_a_m_e is omitted, a default dump file name is constructed by concatenating the base dump file name, a pass number, phase letter, and pass name. The base dump file name is the name of output file produced by the compiler if explicitly specified and not an executable; other- wise it is the source file name. The pass number is determined by the order passes are registered with the compiler's pass manager. This is generally the same as the order of execution, but passes registered by plugins, target-specific passes, or passes that are otherwise regis- tered late are numbered higher than the pass named ffiinnaall, even if they are executed earlier. The phase letter is one of ii (inter-procedural analysis), ll (language-specific), rr (RTL), or tt (tree). The files are created in the directory of the output file. --ffccaallllggrraapphh--iinnffoo --ffccaallllggrraapphh--iinnffoo==_M_A_R_K_E_R_S Makes the compiler output callgraph information for the program, on a per-object-file basis. The information is generated in the com- mon VCG format. It can be decorated with additional, per-node and/or per-edge information, if a list of comma-separated markers is additionally specified. When the "su" marker is specified, the callgraph is decorated with stack usage information; it is equiva- lent to --ffssttaacckk--uussaaggee. When the "da" marker is specified, the callgraph is decorated with information about dynamically allocated objects. When compiling with --ffllttoo, no callgraph information is output along with the object file. At LTO link time, --ffccaallllggrraapphh--iinnffoo may gen- erate multiple callgraph information files next to intermediate LTO output files. --dd_l_e_t_t_e_r_s --ffdduummpp--rrttll--_p_a_s_s --ffdduummpp--rrttll--_p_a_s_s==_f_i_l_e_n_a_m_e Says to make debugging dumps during compilation at times specified by _l_e_t_t_e_r_s. This is used for debugging the RTL-based passes of the compiler. Some --dd_l_e_t_t_e_r_s switches have different meaning when --EE is used for preprocessing. Debug dumps can be enabled with a --ffdduummpp--rrttll switch or some --dd op- tion _l_e_t_t_e_r_s. Here are the possible letters for use in _p_a_s_s and _l_e_t_t_e_r_s, and their meanings: --ffdduummpp--rrttll--aalliiggnnmmeennttss Dump after branch alignments have been computed. --ffdduummpp--rrttll--aassmmccoonnss Dump after fixing rtl statements that have unsatisfied in/out constraints. --ffdduummpp--rrttll--aauuttoo__iinncc__ddeecc Dump after auto-inc-dec discovery. This pass is only run on architectures that have auto inc or auto dec instructions. --ffdduummpp--rrttll--bbaarrrriieerrss Dump after cleaning up the barrier instructions. --ffdduummpp--rrttll--bbbbppaarrtt Dump after partitioning hot and cold basic blocks. --ffdduummpp--rrttll--bbbbrroo Dump after block reordering. --ffdduummpp--rrttll--bbttll11 --ffdduummpp--rrttll--bbttll22 --ffdduummpp--rrttll--bbttll11 and --ffdduummpp--rrttll--bbttll22 enable dumping after the two branch target load optimization passes. --ffdduummpp--rrttll--bbyyppaassss Dump after jump bypassing and control flow optimizations. --ffdduummpp--rrttll--ccoommbbiinnee Dump after the RTL instruction combination pass. --ffdduummpp--rrttll--ccoommppggoottooss Dump after duplicating the computed gotos. --ffdduummpp--rrttll--ccee11 --ffdduummpp--rrttll--ccee22 --ffdduummpp--rrttll--ccee33 --ffdduummpp--rrttll--ccee11, --ffdduummpp--rrttll--ccee22, and --ffdduummpp--rrttll--ccee33 enable dump- ing after the three if conversion passes. --ffdduummpp--rrttll--ccpprroopp__hhaarrddrreegg Dump after hard register copy propagation. --ffdduummpp--rrttll--ccssaa Dump after combining stack adjustments. --ffdduummpp--rrttll--ccssee11 --ffdduummpp--rrttll--ccssee22 --ffdduummpp--rrttll--ccssee11 and --ffdduummpp--rrttll--ccssee22 enable dumping after the two common subexpression elimination passes. --ffdduummpp--rrttll--ddccee Dump after the standalone dead code elimination passes. --ffdduummpp--rrttll--ddbbrr Dump after delayed branch scheduling. --ffdduummpp--rrttll--ddccee11 --ffdduummpp--rrttll--ddccee22 --ffdduummpp--rrttll--ddccee11 and --ffdduummpp--rrttll--ddccee22 enable dumping after the two dead store elimination passes. --ffdduummpp--rrttll--eehh Dump after finalization of EH handling code. --ffdduummpp--rrttll--eehh__rraannggeess Dump after conversion of EH handling range regions. --ffdduummpp--rrttll--eexxppaanndd Dump after RTL generation. --ffdduummpp--rrttll--ffwwpprroopp11 --ffdduummpp--rrttll--ffwwpprroopp22 --ffdduummpp--rrttll--ffwwpprroopp11 and --ffdduummpp--rrttll--ffwwpprroopp22 enable dumping after the two forward propagation passes. --ffdduummpp--rrttll--ggccssee11 --ffdduummpp--rrttll--ggccssee22 --ffdduummpp--rrttll--ggccssee11 and --ffdduummpp--rrttll--ggccssee22 enable dumping after global common subexpression elimination. --ffdduummpp--rrttll--iinniitt--rreeggss Dump after the initialization of the registers. --ffdduummpp--rrttll--iinniittvvaallss Dump after the computation of the initial value sets. --ffdduummpp--rrttll--iinnttoo__ccffggllaayyoouutt Dump after converting to cfglayout mode. --ffdduummpp--rrttll--iirraa Dump after iterated register allocation. --ffdduummpp--rrttll--jjuummpp Dump after the second jump optimization. --ffdduummpp--rrttll--lloooopp22 --ffdduummpp--rrttll--lloooopp22 enables dumping after the rtl loop optimiza- tion passes. --ffdduummpp--rrttll--mmaacchh Dump after performing the machine dependent reorganization pass, if that pass exists. --ffdduummpp--rrttll--mmooddee__ssww Dump after removing redundant mode switches. --ffdduummpp--rrttll--rrnnrreegg Dump after register renumbering. --ffdduummpp--rrttll--oouuttooff__ccffggllaayyoouutt Dump after converting from cfglayout mode. --ffdduummpp--rrttll--ppeeeepphhoollee22 Dump after the peephole pass. --ffdduummpp--rrttll--ppoossttrreellooaadd Dump after post-reload optimizations. --ffdduummpp--rrttll--pprroo__aanndd__eeppiilloogguuee Dump after generating the function prologues and epilogues. --ffdduummpp--rrttll--sscchheedd11 --ffdduummpp--rrttll--sscchheedd22 --ffdduummpp--rrttll--sscchheedd11 and --ffdduummpp--rrttll--sscchheedd22 enable dumping after the basic block scheduling passes. --ffdduummpp--rrttll--rreeee Dump after sign/zero extension elimination. --ffdduummpp--rrttll--sseeqqaabbssttrr Dump after common sequence discovery. --ffdduummpp--rrttll--sshhoorrtteenn Dump after shortening branches. --ffdduummpp--rrttll--ssiibblliinngg Dump after sibling call optimizations. --ffdduummpp--rrttll--sspplliitt11 --ffdduummpp--rrttll--sspplliitt22 --ffdduummpp--rrttll--sspplliitt33 --ffdduummpp--rrttll--sspplliitt44 --ffdduummpp--rrttll--sspplliitt55 These options enable dumping after five rounds of instruction splitting. --ffdduummpp--rrttll--ssmmss Dump after modulo scheduling. This pass is only run on some architectures. --ffdduummpp--rrttll--ssttaacckk Dump after conversion from GCC's "flat register file" registers to the x87's stack-like registers. This pass is only run on x86 variants. --ffdduummpp--rrttll--ssuubbrreegg11 --ffdduummpp--rrttll--ssuubbrreegg22 --ffdduummpp--rrttll--ssuubbrreegg11 and --ffdduummpp--rrttll--ssuubbrreegg22 enable dumping after the two subreg expansion passes. --ffdduummpp--rrttll--uunnsshhaarree Dump after all rtl has been unshared. --ffdduummpp--rrttll--vvaarrttrraacckk Dump after variable tracking. --ffdduummpp--rrttll--vvrreeggss Dump after converting virtual registers to hard registers. --ffdduummpp--rrttll--wweebb Dump after live range splitting. --ffdduummpp--rrttll--rreeggccllaassss --ffdduummpp--rrttll--ssuubbrreeggss__ooff__mmooddee__iinniitt --ffdduummpp--rrttll--ssuubbrreeggss__ooff__mmooddee__ffiinniisshh --ffdduummpp--rrttll--ddffiinniitt --ffdduummpp--rrttll--ddffiinniisshh These dumps are defined but always produce empty files. --ddaa --ffdduummpp--rrttll--aallll Produce all the dumps listed above. --ddAA Annotate the assembler output with miscellaneous debugging in- formation. --ddDD Dump all macro definitions, at the end of preprocessing, in ad- dition to normal output. --ddHH Produce a core dump whenever an error occurs. --ddpp Annotate the assembler output with a comment indicating which pattern and alternative is used. The length and cost of each instruction are also printed. --ddPP Dump the RTL in the assembler output as a comment before each instruction. Also turns on --ddpp annotation. --ddxx Just generate RTL for a function instead of compiling it. Usu- ally used with --ffdduummpp--rrttll--eexxppaanndd. --ffdduummpp--ddeebbuugg Dump debugging information generated during the debug generation phase. --ffdduummpp--eeaarrllyyddeebbuugg Dump debugging information generated during the early debug genera- tion phase. --ffdduummpp--nnooaaddddrr When doing debugging dumps, suppress address output. This makes it more feasible to use diff on debugging dumps for compiler invoca- tions with different compiler binaries and/or different text / bss / data / heap / stack / dso start locations. --ffrreeppoorrtt--bbuugg Collect and dump debug information into a temporary file if an in- ternal compiler error (ICE) occurs. --ffdduummpp--uunnnnuummbbeerreedd When doing debugging dumps, suppress instruction numbers and ad- dress output. This makes it more feasible to use diff on debugging dumps for compiler invocations with different options, in particu- lar with and without --gg. --ffdduummpp--uunnnnuummbbeerreedd--lliinnkkss When doing debugging dumps (see --dd option above), suppress instruc- tion numbers for the links to the previous and next instructions in a sequence. --ffdduummpp--iippaa--_s_w_i_t_c_h --ffdduummpp--iippaa--_s_w_i_t_c_h--_o_p_t_i_o_n_s Control the dumping at various stages of inter-procedural analysis language tree to a file. The file name is generated by appending a switch specific suffix to the source file name, and the file is created in the same directory as the output file. The following dumps are possible: aallll Enables all inter-procedural analysis dumps. ccggrraapphh Dumps information about call-graph optimization, unused func- tion removal, and inlining decisions. iinnlliinnee Dump after function inlining. Additionally, the options --ooppttiimmiizzeedd, --mmiisssseedd, --nnoottee, and --aallll can be provided, with the same meaning as for --ffoopptt--iinnffoo, defaulting to --ooppttiimmiizzeedd. For example, --ffdduummpp--iippaa--iinnlliinnee--ooppttiimmiizzeedd--mmiisssseedd will emit informa- tion on callsites that were inlined, along with callsites that were not inlined. By default, the dump will contain messages about successful opti- mizations (equivalent to --ooppttiimmiizzeedd) together with low-level de- tails about the analysis. --ffdduummpp--llaanngg Dump language-specific information. The file name is made by ap- pending _._l_a_n_g to the source file name. --ffdduummpp--llaanngg--aallll --ffdduummpp--llaanngg--_s_w_i_t_c_h --ffdduummpp--llaanngg--_s_w_i_t_c_h--_o_p_t_i_o_n_s --ffdduummpp--llaanngg--_s_w_i_t_c_h--_o_p_t_i_o_n_s==_f_i_l_e_n_a_m_e Control the dumping of language-specific information. The _o_p_t_i_o_n_s and _f_i_l_e_n_a_m_e portions behave as described in the --ffdduummpp--ttrreeee op- tion. The following _s_w_i_t_c_h values are accepted: aallll Enable all language-specific dumps. ccllaassss Dump class hierarchy information. Virtual table information is emitted unless 'sslliimm' is specified. This option is applicable to C++ only. mmoodduullee Dump module information. Options lliinneennoo (locations), ggrraapphh (reachability), bblloocckkss (clusters), uuiidd (serialization), aalliiaass (mergeable), aassmmnnaammee (Elrond), eehh (mapper) & vvooppss (macros) may provide additional information. This option is applicable to C++ only. rraaww Dump the raw internal tree data. This option is applicable to C++ only. --ffdduummpp--ppaasssseess Print on _s_t_d_e_r_r the list of optimization passes that are turned on and off by the current command-line options. --ffdduummpp--ssttaattiissttiiccss--_o_p_t_i_o_n Enable and control dumping of pass statistics in a separate file. The file name is generated by appending a suffix ending in ..ssttaattiiss-- ttiiccss to the source file name, and the file is created in the same directory as the output file. If the --_o_p_t_i_o_n form is used, --ssttaattss causes counters to be summed over the whole compilation unit while --ddeettaaiillss dumps every event as the passes generate them. The de- fault with no option is to sum counters for each function compiled. --ffdduummpp--ttrreeee--aallll --ffdduummpp--ttrreeee--_s_w_i_t_c_h --ffdduummpp--ttrreeee--_s_w_i_t_c_h--_o_p_t_i_o_n_s --ffdduummpp--ttrreeee--_s_w_i_t_c_h--_o_p_t_i_o_n_s==_f_i_l_e_n_a_m_e Control the dumping at various stages of processing the intermedi- ate language tree to a file. If the --_o_p_t_i_o_n_s form is used, _o_p_t_i_o_n_s is a list of -- separated options which control the details of the dump. Not all options are applicable to all dumps; those that are not meaningful are ignored. The following options are available aaddddrreessss Print the address of each node. Usually this is not meaningful as it changes according to the environment and source file. Its primary use is for tying up a dump file with a debug envi- ronment. aassmmnnaammee If "DECL_ASSEMBLER_NAME" has been set for a given decl, use that in the dump instead of "DECL_NAME". Its primary use is ease of use working backward from mangled names in the assembly file. sslliimm When dumping front-end intermediate representations, inhibit dumping of members of a scope or body of a function merely be- cause that scope has been reached. Only dump such items when they are directly reachable by some other path. When dumping pretty-printed trees, this option inhibits dumping the bodies of control structures. When dumping RTL, print the RTL in slim (condensed) form in- stead of the default LISP-like representation. rraaww Print a raw representation of the tree. By default, trees are pretty-printed into a C-like representation. ddeettaaiillss Enable more detailed dumps (not honored by every dump option). Also include information from the optimization passes. ssttaattss Enable dumping various statistics about the pass (not honored by every dump option). bblloocckkss Enable showing basic block boundaries (disabled in raw dumps). ggrraapphh For each of the other indicated dump files (--ffdduummpp--rrttll--_p_a_s_s), dump a representation of the control flow graph suitable for viewing with GraphViz to _f_i_l_e_._p_a_s_s_i_d_._p_a_s_s_._d_o_t. Each function in the file is pretty-printed as a subgraph, so that GraphViz can render them all in a single plot. This option currently only works for RTL dumps, and the RTL is always dumped in slim form. vvooppss Enable showing virtual operands for every statement. lliinneennoo Enable showing line numbers for statements. uuiidd Enable showing the unique ID ("DECL_UID") for each variable. vveerrbboossee Enable showing the tree dump for each statement. eehh Enable showing the EH region number holding each statement. sscceevv Enable showing scalar evolution analysis details. ooppttiimmiizzeedd Enable showing optimization information (only available in cer- tain passes). mmiisssseedd Enable showing missed optimization information (only available in certain passes). nnoottee Enable other detailed optimization information (only available in certain passes). aallll Turn on all options, except rraaww, sslliimm, vveerrbboossee and lliinneennoo. ooppttaallll Turn on all optimization options, i.e., ooppttiimmiizzeedd, mmiisssseedd, and nnoottee. To determine what tree dumps are available or find the dump for a pass of interest follow the steps below. 1. Invoke GCC with --ffdduummpp--ppaasssseess and in the _s_t_d_e_r_r output look for a code that corresponds to the pass you are interested in. For example, the codes "tree-evrp", "tree-vrp1", and "tree-vrp2" correspond to the three Value Range Propagation passes. The number at the end distinguishes distinct invocations of the same pass. 2. To enable the creation of the dump file, append the pass code to the --ffdduummpp-- option prefix and invoke GCC with it. For exam- ple, to enable the dump from the Early Value Range Propagation pass, invoke GCC with the --ffdduummpp--ttrreeee--eevvrrpp option. Optionally, you may specify the name of the dump file. If you don't spec- ify one, GCC creates as described below. 3. Find the pass dump in a file whose name is composed of three components separated by a period: the name of the source file GCC was invoked to compile, a numeric suffix indicating the pass number followed by the letter tt for tree passes (and the letter rr for RTL passes), and finally the pass code. For exam- ple, the Early VRP pass dump might be in a file named _m_y_- _f_i_l_e_._c_._0_3_8_t_._e_v_r_p in the current working directory. Note that the numeric codes are not stable and may change from one ver- sion of GCC to another. --ffoopptt--iinnffoo --ffoopptt--iinnffoo--_o_p_t_i_o_n_s --ffoopptt--iinnffoo--_o_p_t_i_o_n_s==_f_i_l_e_n_a_m_e Controls optimization dumps from various optimization passes. If the --_o_p_t_i_o_n_s form is used, _o_p_t_i_o_n_s is a list of -- separated option keywords to select the dump details and optimizations. The _o_p_t_i_o_n_s can be divided into three groups: 1. options describing what kinds of messages should be emitted, 2. options describing the verbosity of the dump, and 3. options describing which optimizations should be included. The options from each group can be freely mixed as they are non-overlapping. However, in case of any conflicts, the later op- tions override the earlier options on the command line. The following options control which kinds of messages should be emitted: ooppttiimmiizzeedd Print information when an optimization is successfully applied. It is up to a pass to decide which information is relevant. For example, the vectorizer passes print the source location of loops which are successfully vectorized. mmiisssseedd Print information about missed optimizations. Individual passes control which information to include in the output. nnoottee Print verbose information about optimizations, such as certain transformations, more detailed messages about decisions etc. aallll Print detailed optimization information. This includes ooppttii-- mmiizzeedd, mmiisssseedd, and nnoottee. The following option controls the dump verbosity: iinntteerrnnaallss By default, only "high-level" messages are emitted. This option enables additional, more detailed, messages, which are likely to only be of interest to GCC developers. One or more of the following option keywords can be used to de- scribe a group of optimizations: iippaa Enable dumps from all interprocedural optimizations. lloooopp Enable dumps from all loop optimizations. iinnlliinnee Enable dumps from all inlining optimizations. oommpp Enable dumps from all OMP (Offloading and Multi Processing) op- timizations. vveecc Enable dumps from all vectorization optimizations. ooppttaallll Enable dumps from all optimizations. This is a superset of the optimization groups listed above. If _o_p_t_i_o_n_s is omitted, it defaults to ooppttiimmiizzeedd--ooppttaallll, which means to dump messages about successful optimizations from all the passes, omitting messages that are treated as "internals". If the _f_i_l_e_n_a_m_e is provided, then the dumps from all the applicable optimizations are concatenated into the _f_i_l_e_n_a_m_e. Otherwise the dump is output onto _s_t_d_e_r_r. Though multiple --ffoopptt--iinnffoo options are accepted, only one of them can include a _f_i_l_e_n_a_m_e. If other file- names are provided then all but the first such option are ignored. Note that the output _f_i_l_e_n_a_m_e is overwritten in case of multiple translation units. If a combined output from multiple translation units is desired, _s_t_d_e_r_r should be used instead. In the following example, the optimization info is output to _s_t_d_e_r_r: gcc -O3 -fopt-info This example: gcc -O3 -fopt-info-missed=missed.all outputs missed optimization report from all the passes into _m_i_s_s_e_d_._a_l_l, and this one: gcc -O2 -ftree-vectorize -fopt-info-vec-missed prints information about missed optimization opportunities from vectorization passes on _s_t_d_e_r_r. Note that --ffoopptt--iinnffoo--vveecc--mmiisssseedd is equivalent to --ffoopptt--iinnffoo--mmiisssseedd--vveecc. The order of the optimization group names and message types listed after --ffoopptt--iinnffoo does not mat- ter. As another example, gcc -O3 -fopt-info-inline-optimized-missed=inline.txt outputs information about missed optimizations as well as optimized locations from all the inlining passes into _i_n_l_i_n_e_._t_x_t. Finally, consider: gcc -fopt-info-vec-missed=vec.miss -fopt-info-loop-optimized=loop.opt Here the two output filenames _v_e_c_._m_i_s_s and _l_o_o_p_._o_p_t are in conflict since only one output file is allowed. In this case, only the first option takes effect and the subsequent options are ignored. Thus only _v_e_c_._m_i_s_s is produced which contains dumps from the vectorizer about missed opportunities. --ffssaavvee--ooppttiimmiizzaattiioonn--rreeccoorrdd Write a SRCFILE.opt-record.json.gz file detailing what optimiza- tions were performed, for those optimizations that support --ffoopptt--iinnffoo. This option is experimental and the format of the data within the compressed JSON file is subject to change. It is roughly equivalent to a machine-readable version of --ffoopptt--iinnffoo--aallll, as a collection of messages with source file, line number and column number, with the following additional data for each message: * the execution count of the code being optimized, along with metadata about whether this was from actual profile data, or just an estimate, allowing consumers to prioritize messages by code hotness, * the function name of the code being optimized, where applica- ble, * the "inlining chain" for the code being optimized, so that when a function is inlined into several different places (which might themselves be inlined), the reader can distinguish be- tween the copies, * objects identifying those parts of the message that refer to expressions, statements or symbol-table nodes, which of these categories they are, and, when available, their source code lo- cation, * the GCC pass that emitted the message, and * the location in GCC's own code from which the message was emit- ted Additionally, some messages are logically nested within other mes- sages, reflecting implementation details of the optimization passes. --ffsscchheedd--vveerrbboossee==_n On targets that use instruction scheduling, this option controls the amount of debugging output the scheduler prints to the dump files. For _n greater than zero, --ffsscchheedd--vveerrbboossee outputs the same informa- tion as --ffdduummpp--rrttll--sscchheedd11 and --ffdduummpp--rrttll--sscchheedd22. For _n greater than one, it also output basic block probabilities, detailed ready list information and unit/insn info. For _n greater than two, it includes RTL at abort point, control-flow and regions info. And for _n over four, --ffsscchheedd--vveerrbboossee also includes dependence info. --ffeennaabbllee--_k_i_n_d--_p_a_s_s --ffddiissaabbllee--_k_i_n_d--_p_a_s_s==_r_a_n_g_e_-_l_i_s_t This is a set of options that are used to explicitly disable/enable optimization passes. These options are intended for use for debug- ging GCC. Compiler users should use regular options for en- abling/disabling passes instead. --ffddiissaabbllee--iippaa--_p_a_s_s Disable IPA pass _p_a_s_s. _p_a_s_s is the pass name. If the same pass is statically invoked in the compiler multiple times, the pass name should be appended with a sequential number starting from 1. --ffddiissaabbllee--rrttll--_p_a_s_s --ffddiissaabbllee--rrttll--_p_a_s_s==_r_a_n_g_e_-_l_i_s_t Disable RTL pass _p_a_s_s. _p_a_s_s is the pass name. If the same pass is statically invoked in the compiler multiple times, the pass name should be appended with a sequential number starting from 1. _r_a_n_g_e_-_l_i_s_t is a comma-separated list of function ranges or assembler names. Each range is a number pair sepa- rated by a colon. The range is inclusive in both ends. If the range is trivial, the number pair can be simplified as a single number. If the function's call graph node's _u_i_d falls within one of the specified ranges, the _p_a_s_s is disabled for that function. The _u_i_d is shown in the function header of a dump file, and the pass names can be dumped by using option --ffdduummpp--ppaasssseess. --ffddiissaabbllee--ttrreeee--_p_a_s_s --ffddiissaabbllee--ttrreeee--_p_a_s_s==_r_a_n_g_e_-_l_i_s_t Disable tree pass _p_a_s_s. See --ffddiissaabbllee--rrttll for the description of option arguments. --ffeennaabbllee--iippaa--_p_a_s_s Enable IPA pass _p_a_s_s. _p_a_s_s is the pass name. If the same pass is statically invoked in the compiler multiple times, the pass name should be appended with a sequential number starting from 1. --ffeennaabbllee--rrttll--_p_a_s_s --ffeennaabbllee--rrttll--_p_a_s_s==_r_a_n_g_e_-_l_i_s_t Enable RTL pass _p_a_s_s. See --ffddiissaabbllee--rrttll for option argument description and examples. --ffeennaabbllee--ttrreeee--_p_a_s_s --ffeennaabbllee--ttrreeee--_p_a_s_s==_r_a_n_g_e_-_l_i_s_t Enable tree pass _p_a_s_s. See --ffddiissaabbllee--rrttll for the description of option arguments. Here are some examples showing uses of these options. # disable ccp1 for all functions -fdisable-tree-ccp1 # disable complete unroll for function whose cgraph node uid is 1 -fenable-tree-cunroll=1 # disable gcse2 for functions at the following ranges [1,1], # [300,400], and [400,1000] # disable gcse2 for functions foo and foo2 -fdisable-rtl-gcse2=foo,foo2 # disable early inlining -fdisable-tree-einline # disable ipa inlining -fdisable-ipa-inline # enable tree full unroll -fenable-tree-unroll --ffcchheecckkiinngg --ffcchheecckkiinngg==_n Enable internal consistency checking. The default depends on the compiler configuration. --ffcchheecckkiinngg==22 enables further internal con- sistency checking that might affect code generation. --ffrraannddoomm--sseeeedd==_s_t_r_i_n_g This option provides a seed that GCC uses in place of random num- bers in generating certain symbol names that have to be different in every compiled file. It is also used to place unique stamps in coverage data files and the object files that produce them. You can use the --ffrraannddoomm--sseeeedd option to produce reproducibly identical object files. The _s_t_r_i_n_g can either be a number (decimal, octal or hex) or an ar- bitrary string (in which case it's converted to a number by comput- ing CRC32). The _s_t_r_i_n_g should be different for every file you compile. --ssaavvee--tteemmppss Store the usual "temporary" intermediate files permanently; name them as auxiliary output files, as specified described under --dduummpp-- bbaassee and --dduummppddiirr. When used in combination with the --xx command-line option, --ssaavvee--tteemmppss is sensible enough to avoid overwriting an input source file with the same extension as an intermediate file. The corre- sponding intermediate file may be obtained by renaming the source file before using --ssaavvee--tteemmppss. --ssaavvee--tteemmppss==ccwwdd Equivalent to --ssaavvee--tteemmppss --dduummppddiirr ..//. --ssaavvee--tteemmppss==oobbjj Equivalent to --ssaavvee--tteemmppss --dduummppddiirr _oo_uu_tt_dd_ii_rr_//, where _o_u_t_d_i_r_/ is the directory of the output file specified after the --oo option, includ- ing any directory separators. If the --oo option is not used, the --ssaavvee--tteemmppss==oobbjj switch behaves like --ssaavvee--tteemmppss==ccwwdd. --ttiimmee[==_f_i_l_e] Report the CPU time taken by each subprocess in the compilation se- quence. For C source files, this is the compiler proper and assem- bler (plus the linker if linking is done). Without the specification of an output file, the output looks like this: # cc1 0.12 0.01 # as 0.00 0.01 The first number on each line is the "user time", that is time spent executing the program itself. The second number is "system time", time spent executing operating system routines on behalf of the program. Both numbers are in seconds. With the specification of an output file, the output is appended to the named file, and it looks like this: 0.12 0.01 cc1 0.00 0.01 as The "user time" and the "system time" are moved before the program name, and the options passed to the program are displayed, so that one can later tell what file was being compiled, and with which op- tions. --ffdduummpp--ffiinnaall--iinnssnnss[==_f_i_l_e] Dump the final internal representation (RTL) to _f_i_l_e. If the op- tional argument is omitted (or if _f_i_l_e is "."), the name of the dump file is determined by appending ".gkd" to the dump base name, see --dduummppbbaassee. --ffccoommppaarree--ddeebbuugg[==_o_p_t_s] If no error occurs during compilation, run the compiler a second time, adding _o_p_t_s and --ffccoommppaarree--ddeebbuugg--sseeccoonndd to the arguments passed to the second compilation. Dump the final internal repre- sentation in both compilations, and print an error if they differ. If the equal sign is omitted, the default --ggttooggggllee is used. The environment variable GGCCCC__CCOOMMPPAARREE__DDEEBBUUGG, if defined, non-empty and nonzero, implicitly enables --ffccoommppaarree--ddeebbuugg. If GGCCCC__CCOOMM-- PPAARREE__DDEEBBUUGG is defined to a string starting with a dash, then it is used for _o_p_t_s, otherwise the default --ggttooggggllee is used. --ffccoommppaarree--ddeebbuugg==, with the equal sign but without _o_p_t_s, is equiva- lent to --ffnnoo--ccoommppaarree--ddeebbuugg, which disables the dumping of the final representation and the second compilation, preventing even GGCCCC__CCOOMM-- PPAARREE__DDEEBBUUGG from taking effect. To verify full coverage during --ffccoommppaarree--ddeebbuugg testing, set GGCCCC__CCOOMMPPAARREE__DDEEBBUUGG to say --ffccoommppaarree--ddeebbuugg--nnoott--oovveerrrriiddddeenn, which GCC rejects as an invalid option in any actual compilation (rather than preprocessing, assembly or linking). To get just a warning, set- ting GGCCCC__CCOOMMPPAARREE__DDEEBBUUGG to --ww%%nn--ffccoommppaarree--ddeebbuugg nnoott oovveerrrriiddddeenn will do. --ffccoommppaarree--ddeebbuugg--sseeccoonndd This option is implicitly passed to the compiler for the second compilation requested by --ffccoommppaarree--ddeebbuugg, along with options to si- lence warnings, and omitting other options that would cause the compiler to produce output to files or to standard output as a side effect. Dump files and preserved temporary files are renamed so as to contain the ".gk" additional extension during the second compi- lation, to avoid overwriting those generated by the first. When this option is passed to the compiler driver, it causes the _f_i_r_s_t compilation to be skipped, which makes it useful for little other than debugging the compiler proper. --ggttooggggllee Turn off generation of debug info, if leaving out this option gen- erates it, or turn it on at level 2 otherwise. The position of this argument in the command line does not matter; it takes effect after all other options are processed, and it does so only once, no matter how many times it is given. This is mainly intended to be used with --ffccoommppaarree--ddeebbuugg. --ffvvaarr--ttrraacckkiinngg--aassssiiggnnmmeennttss--ttooggggllee Toggle --ffvvaarr--ttrraacckkiinngg--aassssiiggnnmmeennttss, in the same way that --ggttooggggllee toggles --gg. --QQ Makes the compiler print out each function name as it is compiled, and print some statistics about each pass when it finishes. --ffttiimmee--rreeppoorrtt Makes the compiler print some statistics about the time consumed by each pass when it finishes. --ffttiimmee--rreeppoorrtt--ddeettaaiillss Record the time consumed by infrastructure parts separately for each pass. --ffiirraa--vveerrbboossee==_n Control the verbosity of the dump file for the integrated register allocator. The default value is 5. If the value _n is greater or equal to 10, the dump output is sent to stderr using the same for- mat as _n minus 10. --ffllttoo--rreeppoorrtt Prints a report with internal details on the workings of the link- time optimizer. The contents of this report vary from version to version. It is meant to be useful to GCC developers when process- ing object files in LTO mode (via --ffllttoo). Disabled by default. --ffllttoo--rreeppoorrtt--wwppaa Like --ffllttoo--rreeppoorrtt, but only print for the WPA phase of link-time optimization. --ffmmeemm--rreeppoorrtt Makes the compiler print some statistics about permanent memory al- location when it finishes. --ffmmeemm--rreeppoorrtt--wwppaa Makes the compiler print some statistics about permanent memory al- location for the WPA phase only. --ffpprree--iippaa--mmeemm--rreeppoorrtt --ffppoosstt--iippaa--mmeemm--rreeppoorrtt Makes the compiler print some statistics about permanent memory al- location before or after interprocedural optimization. --ffpprrooffiillee--rreeppoorrtt Makes the compiler print some statistics about consistency of the (estimated) profile and effect of individual passes. --ffssttaacckk--uussaaggee Makes the compiler output stack usage information for the program, on a per-function basis. The filename for the dump is made by ap- pending _._s_u to the _a_u_x_n_a_m_e. _a_u_x_n_a_m_e is generated from the name of the output file, if explicitly specified and it is not an exe- cutable, otherwise it is the basename of the source file. An entry is made up of three fields: * The name of the function. * A number of bytes. * One or more qualifiers: "static", "dynamic", "bounded". The qualifier "static" means that the function manipulates the stack statically: a fixed number of bytes are allocated for the frame on function entry and released on function exit; no stack ad- justments are otherwise made in the function. The second field is this fixed number of bytes. The qualifier "dynamic" means that the function manipulates the stack dynamically: in addition to the static allocation described above, stack adjustments are made in the body of the function, for example to push/pop arguments around function calls. If the quali- fier "bounded" is also present, the amount of these adjustments is bounded at compile time and the second field is an upper bound of the total amount of stack used by the function. If it is not present, the amount of these adjustments is not bounded at compile time and the second field only represents the bounded part. --ffssttaattss Emit statistics about front-end processing at the end of the compi- lation. This option is supported only by the C++ front end, and the information is generally only useful to the G++ development team. --ffddbbgg--ccnntt--lliisstt Print the name and the counter upper bound for all debug counters. --ffddbbgg--ccnntt==_c_o_u_n_t_e_r_-_v_a_l_u_e_-_l_i_s_t Set the internal debug counter lower and upper bound. _c_o_u_n_t_e_r_- _v_a_l_u_e_-_l_i_s_t is a comma-separated list of _n_a_m_e:_l_o_w_e_r___b_o_u_n_d_1-_u_p_- _p_e_r___b_o_u_n_d_1 [:_l_o_w_e_r___b_o_u_n_d_2-_u_p_p_e_r___b_o_u_n_d_2...] tuples which sets the name of the counter and list of closed intervals. The _l_o_w_e_r___b_o_u_n_d is optional and is zero initialized if not set. For example, with --ffddbbgg--ccnntt==ddccee::22--44::1100--1111,,ttaaiill__ccaallll::1100, "dbg_cnt(dce)" returns true only for second, third, fourth, tenth and eleventh invocation. For "dbg_cnt(tail_call)" true is returned for first 10 invocations. --pprriinntt--ffiillee--nnaammee==_l_i_b_r_a_r_y Print the full absolute name of the library file _l_i_b_r_a_r_y that would be used when linking---and don't do anything else. With this op- tion, GCC does not compile or link anything; it just prints the file name. --pprriinntt--mmuullttii--ddiirreeccttoorryy Print the directory name corresponding to the multilib selected by any other switches present in the command line. This directory is supposed to exist in GGCCCC__EEXXEECC__PPRREEFFIIXX. --pprriinntt--mmuullttii--lliibb Print the mapping from multilib directory names to compiler switches that enable them. The directory name is separated from the switches by ;;, and each switch starts with an @@ instead of the --, without spaces between multiple switches. This is supposed to ease shell processing. --pprriinntt--mmuullttii--ooss--ddiirreeccttoorryy Print the path to OS libraries for the selected multilib, relative to some _l_i_b subdirectory. If OS libraries are present in the _l_i_b subdirectory and no multilibs are used, this is usually just _., if OS libraries are present in _l_i_b_s_u_f_f_i_x sibling directories this prints e.g. _._._/_l_i_b_6_4, _._._/_l_i_b or _._._/_l_i_b_3_2, or if OS libraries are present in _l_i_b_/_s_u_b_d_i_r subdirectories it prints e.g. _a_m_d_6_4, _s_p_a_r_c_v_9 or _e_v_6. --pprriinntt--mmuullttiiaarrcchh Print the path to OS libraries for the selected multiarch, relative to some _l_i_b subdirectory. --pprriinntt--pprroogg--nnaammee==_p_r_o_g_r_a_m Like --pprriinntt--ffiillee--nnaammee, but searches for a program such as ccpppp. --pprriinntt--lliibbggcccc--ffiillee--nnaammee Same as --pprriinntt--ffiillee--nnaammee==lliibbggcccc..aa. This is useful when you use --nnoossttddlliibb or --nnooddeeffaauullttlliibbss but you do want to link with _l_i_b_g_c_c_._a. You can do: gcc -nostdlib ... `gcc -print-libgcc-file-name` --pprriinntt--sseeaarrcchh--ddiirrss Print the name of the configured installation directory and a list of program and library directories ggcccc searches---and don't do any- thing else. This is useful when ggcccc prints the error message iinnssttaallllaattiioonn pprroobb-- lleemm,, ccaannnnoott eexxeecc ccpppp00:: NNoo ssuucchh ffiillee oorr ddiirreeccttoorryy. To resolve this you either need to put _c_p_p_0 and the other compiler components where ggcccc expects to find them, or you can set the environment variable GGCCCC__EEXXEECC__PPRREEFFIIXX to the directory where you installed them. Don't forget the trailing //. --pprriinntt--ssyyssrroooott Print the target sysroot directory that is used during compilation. This is the target sysroot specified either at configure time or using the ----ssyyssrroooott option, possibly with an extra suffix that de- pends on compilation options. If no target sysroot is specified, the option prints nothing. --pprriinntt--ssyyssrroooott--hheeaaddeerrss--ssuuffffiixx Print the suffix added to the target sysroot when searching for headers, or give an error if the compiler is not configured with such a suffix---and don't do anything else. --dduummppmmaacchhiinnee Print the compiler's target machine (for example, ii668866--ppcc--lliinnuuxx--ggnnuu)---and don't do anything else. --dduummppvveerrssiioonn Print the compiler version (for example, 3.0, 6.3.0 or 7)---and don't do anything else. This is the compiler version used in filesystem paths and specs. Depending on how the compiler has been configured it can be just a single number (major version), two num- bers separated by a dot (major and minor version) or three numbers separated by dots (major, minor and patchlevel version). --dduummppffuullllvveerrssiioonn Print the full compiler version---and don't do anything else. The output is always three numbers separated by dots, major, minor and patchlevel version. --dduummppssppeeccss Print the compiler's built-in specs---and don't do anything else. (This is used when GCC itself is being built.) MMaacchhiinnee--DDeeppeennddeenntt OOppttiioonnss Each target machine supported by GCC can have its own options---for ex- ample, to allow you to compile for a particular processor variant or ABI, or to control optimizations specific to that machine. By conven- tion, the names of machine-specific options start with --mm. Some configurations of the compiler also support additional target-spe- cific options, usually for compatibility with other compilers on the same platform. _A_A_r_c_h_6_4 _O_p_t_i_o_n_s These options are defined for AArch64 implementations: --mmaabbii==_n_a_m_e Generate code for the specified data model. Permissible values are iillpp3322 for SysV-like data model where int, long int and pointers are 32 bits, and llpp6644 for SysV-like data model where int is 32 bits, but long int and pointers are 64 bits. The default depends on the specific target configuration. Note that the LP64 and ILP32 ABIs are not link-compatible; you must com- pile your entire program with the same ABI, and link with a compat- ible set of libraries. --mmbbiigg--eennddiiaann Generate big-endian code. This is the default when GCC is config- ured for an aaaarrcchh6644__bbee--**--** target. --mmggeenneerraall--rreeggss--oonnllyy Generate code which uses only the general-purpose registers. This will prevent the compiler from using floating-point and Advanced SIMD registers but will not impose any restrictions on the assem- bler. --mmlliittttllee--eennddiiaann Generate little-endian code. This is the default when GCC is con- figured for an aaaarrcchh6644--**--** but not an aaaarrcchh6644__bbee--**--** target. --mmccmmooddeell==ttiinnyy Generate code for the tiny code model. The program and its stati- cally defined symbols must be within 1MB of each other. Programs can be statically or dynamically linked. --mmccmmooddeell==ssmmaallll Generate code for the small code model. The program and its stati- cally defined symbols must be within 4GB of each other. Programs can be statically or dynamically linked. This is the default code model. --mmccmmooddeell==llaarrggee Generate code for the large code model. This makes no assumptions about addresses and sizes of sections. Programs can be statically linked only. The --mmccmmooddeell==llaarrggee option is incompatible with --mmaabbii==iillpp3322, --ffppiicc and --ffPPIICC. --mmssttrriicctt--aalliiggnn --mmnnoo--ssttrriicctt--aalliiggnn Avoid or allow generating memory accesses that may not be aligned on a natural object boundary as described in the architecture spec- ification. --mmoommiitt--lleeaaff--ffrraammee--ppooiinntteerr --mmnnoo--oommiitt--lleeaaff--ffrraammee--ppooiinntteerr Omit or keep the frame pointer in leaf functions. The former be- havior is the default. --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd==_g_u_a_r_d --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--rreegg==_r_e_g --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ooffffsseett==_o_f_f_s_e_t Generate stack protection code using canary at _g_u_a_r_d. Supported locations are gglloobbaall for a global canary or ssyyssrreegg for a canary in an appropriate system register. With the latter choice the options --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--rreegg==_r_e_g and --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ooffffsseett==_o_f_f_s_e_t furthermore specify which system register to use as base register for reading the canary, and from what offset from that base register. There is no default reg- ister or offset as this is entirely for use within the Linux ker- nel. --mmttllss--ddiiaalleecctt==ddeesscc Use TLS descriptors as the thread-local storage mechanism for dy- namic accesses of TLS variables. This is the default. --mmttllss--ddiiaalleecctt==ttrraaddiittiioonnaall Use traditional TLS as the thread-local storage mechanism for dy- namic accesses of TLS variables. --mmttllss--ssiizzee==_s_i_z_e Specify bit size of immediate TLS offsets. Valid values are 12, 24, 32, 48. This option requires binutils 2.26 or newer. --mmffiixx--ccoorrtteexx--aa5533--883355776699 --mmnnoo--ffiixx--ccoorrtteexx--aa5533--883355776699 Enable or disable the workaround for the ARM Cortex-A53 erratum number 835769. This involves inserting a NOP instruction between memory instructions and 64-bit integer multiply-accumulate instruc- tions. --mmffiixx--ccoorrtteexx--aa5533--884433441199 --mmnnoo--ffiixx--ccoorrtteexx--aa5533--884433441199 Enable or disable the workaround for the ARM Cortex-A53 erratum number 843419. This erratum workaround is made at link time and this will only pass the corresponding flag to the linker. --mmllooww--pprreecciissiioonn--rreecciipp--ssqqrrtt --mmnnoo--llooww--pprreecciissiioonn--rreecciipp--ssqqrrtt Enable or disable the reciprocal square root approximation. This option only has an effect if --ffffaasstt--mmaatthh or --ffuunnssaaffee--mmaatthh--ooppttiimmiizzaa-- ttiioonnss is used as well. Enabling this reduces precision of recipro- cal square root results to about 16 bits for single precision and to 32 bits for double precision. --mmllooww--pprreecciissiioonn--ssqqrrtt --mmnnoo--llooww--pprreecciissiioonn--ssqqrrtt Enable or disable the square root approximation. This option only has an effect if --ffffaasstt--mmaatthh or --ffuunnssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss is used as well. Enabling this reduces precision of square root results to about 16 bits for single precision and to 32 bits for double preci- sion. If enabled, it implies --mmllooww--pprreecciissiioonn--rreecciipp--ssqqrrtt. --mmllooww--pprreecciissiioonn--ddiivv --mmnnoo--llooww--pprreecciissiioonn--ddiivv Enable or disable the division approximation. This option only has an effect if --ffffaasstt--mmaatthh or --ffuunnssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss is used as well. Enabling this reduces precision of division results to about 16 bits for single precision and to 32 bits for double precision. --mmttrraacckk--ssppeeccuullaattiioonn --mmnnoo--ttrraacckk--ssppeeccuullaattiioonn Enable or disable generation of additional code to track specula- tive execution through conditional branches. The tracking state can then be used by the compiler when expanding calls to "__builtin_speculation_safe_copy" to permit a more efficient code sequence to be generated. --mmoouuttlliinnee--aattoommiiccss --mmnnoo--oouuttlliinnee--aattoommiiccss Enable or disable calls to out-of-line helpers to implement atomic operations. These helpers will, at runtime, determine if the LSE instructions from ARMv8.1-A can be used; if not, they will use the load/store-exclusive instructions that are present in the base ARMv8.0 ISA. This option is only applicable when compiling for the base ARMv8.0 instruction set. If using a later revision, e.g. --mmaarrcchh==aarrmmvv88..11--aa or --mmaarrcchh==aarrmmvv88--aa++llssee, the ARMv8.1-Atomics instructions will be used directly. The same applies when using --mmccppuu== when the se- lected cpu supports the llssee feature. This option is on by default. --mmaarrcchh==_n_a_m_e Specify the name of the target architecture and, optionally, one or more feature modifiers. This option has the form --mmaarrcchh==_a_r_c_h{++[nnoo]_f_e_a_t_u_r_e}*. The table below summarizes the permissible values for _a_r_c_h and the features that they enable by default: _a_r_c_h _v_a_l_u_e : _A_r_c_h_i_t_e_c_t_u_r_e : _I_n_c_l_u_d_e_s _b_y _d_e_f_a_u_l_t aarrmmvv88--aa : Armv8-A : ++ffpp, ++ssiimmdd aarrmmvv88..11--aa : Armv8.1-A : aarrmmvv88--aa, ++ccrrcc, ++llssee, ++rrddmmaa aarrmmvv88..22--aa : Armv8.2-A : aarrmmvv88..11--aa aarrmmvv88..33--aa : Armv8.3-A : aarrmmvv88..22--aa, ++ppaauutthh aarrmmvv88..44--aa : Armv8.4-A : aarrmmvv88..33--aa, ++ffllaaggmm, ++ffpp1166ffmmll, ++ddoottpprroodd aarrmmvv88..55--aa : Armv8.5-A : aarrmmvv88..44--aa, ++ssbb, ++ssssbbss, ++pprreeddrreess aarrmmvv88..66--aa : Armv8.6-A : aarrmmvv88..55--aa, ++bbff1166, ++ii88mmmm aarrmmvv88..77--aa : Armv8.7-A : aarrmmvv88..66--aa, ++llss6644 aarrmmvv88..88--aa : Armv8.8-a : aarrmmvv88..77--aa, ++mmooppss aarrmmvv99--aa : Armv9-A : aarrmmvv88..55--aa, ++ssvvee, ++ssvvee22 aarrmmvv88--rr : Armv8-R : aarrmmvv88--rr The value nnaattiivvee is available on native AArch64 GNU/Linux and causes the compiler to pick the architecture of the host system. This option has no effect if the compiler is unable to recognize the architecture of the host system, The permissible values for _f_e_a_t_u_r_e are listed in the sub-section on aaaarrcchh6644--ffeeaattuurree--mmooddiiffiieerrss,,,,--mmaarrcchh aanndd --mmccppuu FFeeaattuurree MMooddiiffiieerrss. Where conflicting feature modifiers are specified, the right-most feature is used. GCC uses _n_a_m_e to determine what kind of instructions it can emit when generating assembly code. If --mmaarrcchh is specified without ei- ther of --mmttuunnee or --mmccppuu also being specified, the code is tuned to perform well across a range of target processors implementing the target architecture. --mmttuunnee==_n_a_m_e Specify the name of the target processor for which GCC should tune the performance of the code. Permissible values for this option are: ggeenneerriicc, ccoorrtteexx--aa3355, ccoorrtteexx--aa5533, ccoorrtteexx--aa5555, ccoorrtteexx--aa5577, ccoorr-- tteexx--aa7722, ccoorrtteexx--aa7733, ccoorrtteexx--aa7755, ccoorrtteexx--aa7766, ccoorrtteexx--aa7766aaee, ccoorr-- tteexx--aa7777, ccoorrtteexx--aa6655, ccoorrtteexx--aa6655aaee, ccoorrtteexx--aa3344, ccoorrtteexx--aa7788, ccoorr-- tteexx--aa7788aaee, ccoorrtteexx--aa7788cc, aarreess, eexxyynnooss--mm11, eemmaagg, ffaallkkoorr, nneeoo-- vveerrssee--551122ttvvbb, nneeoovveerrssee--ee11, nneeoovveerrssee--nn11, nneeoovveerrssee--nn22, nneeoovveerrssee--vv11, qqddff2244xxxx, ssaapphhiirraa, pphheeccddaa, xxggeennee11, vvuullccaann, oocctteeoonnttxx, oocctteeoonnttxx8811, oocctteeoonnttxx8833, oocctteeoonnttxx22, oocctteeoonnttxx22tt9988, oocctteeoonnttxx22tt9966 oocctteeoonnttxx22tt9933, oocctteeoonnttxx22ff9955, oocctteeoonnttxx22ff9955nn, oocctteeoonnttxx22ff9955mmmm, aa6644ffxx, tthhuunnddeerrxx, tthhuunn-- ddeerrxxtt8888, tthhuunnddeerrxxtt8888pp11, tthhuunnddeerrxxtt8811, ttssvv111100, tthhuunnddeerrxxtt8833, tthhuunn-- ddeerrxx22tt9999, tthhuunnddeerrxx33tt111100, zzeeuuss, ccoorrtteexx--aa5577..ccoorrtteexx--aa5533, ccoorr-- tteexx--aa7722..ccoorrtteexx--aa5533, ccoorrtteexx--aa7733..ccoorrtteexx--aa3355, ccoorrtteexx--aa7733..ccoorrtteexx--aa5533, ccoorrtteexx--aa7755..ccoorrtteexx--aa5555, ccoorrtteexx--aa7766..ccoorrtteexx--aa5555, ccoorrtteexx--rr8822, ccoorr-- tteexx--xx11, ccoorrtteexx--xx22, ccoorrtteexx--aa551100, ccoorrtteexx--aa771100, aammppeerree11, nnaattiivvee. The values ccoorrtteexx--aa5577..ccoorrtteexx--aa5533, ccoorrtteexx--aa7722..ccoorrtteexx--aa5533, ccoorr-- tteexx--aa7733..ccoorrtteexx--aa3355, ccoorrtteexx--aa7733..ccoorrtteexx--aa5533, ccoorrtteexx--aa7755..ccoorrtteexx--aa5555, ccoorrtteexx--aa7766..ccoorrtteexx--aa5555 specify that GCC should tune for a big.LITTLE system. The value nneeoovveerrssee--551122ttvvbb specifies that GCC should tune for Neo- verse cores that (a) implement SVE and (b) have a total vector bandwidth of 512 bits per cycle. In other words, the option tells GCC to tune for Neoverse cores that can execute 4 128-bit Advanced SIMD arithmetic instructions a cycle and that can execute an equiv- alent number of SVE arithmetic instructions per cycle (2 for 256-bit SVE, 4 for 128-bit SVE). This is more general than tuning for a specific core like Neoverse V1 but is more specific than the default tuning described below. Additionally on native AArch64 GNU/Linux systems the value nnaattiivvee tunes performance to the host system. This option has no effect if the compiler is unable to recognize the processor of the host sys- tem. Where none of --mmttuunnee==, --mmccppuu== or --mmaarrcchh== are specified, the code is tuned to perform well across a range of target processors. This option cannot be suffixed by feature modifiers. --mmccppuu==_n_a_m_e Specify the name of the target processor, optionally suffixed by one or more feature modifiers. This option has the form --mmccppuu==_c_p_u{++[nnoo]_f_e_a_t_u_r_e}*, where the permissible values for _c_p_u are the same as those available for --mmttuunnee. The permissible values for _f_e_a_t_u_r_e are documented in the sub-section on aaaarrcchh6644--ffeeaattuurree--mmooddii-- ffiieerrss,,,,--mmaarrcchh aanndd --mmccppuu FFeeaattuurree MMooddiiffiieerrss. Where conflicting fea- ture modifiers are specified, the right-most feature is used. GCC uses _n_a_m_e to determine what kind of instructions it can emit when generating assembly code (as if by --mmaarrcchh) and to determine the target processor for which to tune for performance (as if by --mmttuunnee). Where this option is used in conjunction with --mmaarrcchh or --mmttuunnee, those options take precedence over the appropriate part of this option. --mmccppuu==nneeoovveerrssee--551122ttvvbb is special in that it does not refer to a specific core, but instead refers to all Neoverse cores that (a) implement SVE and (b) have a total vector bandwidth of 512 bits a cycle. Unless overridden by --mmaarrcchh, --mmccppuu==nneeoovveerrssee--551122ttvvbb gener- ates code that can run on a Neoverse V1 core, since Neoverse V1 is the first Neoverse core with these properties. Unless overridden by --mmttuunnee, --mmccppuu==nneeoovveerrssee--551122ttvvbb tunes code in the same way as for --mmttuunnee==nneeoovveerrssee--551122ttvvbb. --mmoovveerrrriiddee==_s_t_r_i_n_g Override tuning decisions made by the back-end in response to a --mmttuunnee== switch. The syntax, semantics, and accepted values for _s_t_r_i_n_g in this option are not guaranteed to be consistent across releases. This option is only intended to be useful when developing GCC. --mmvveerrbboossee--ccoosstt--dduummpp Enable verbose cost model dumping in the debug dump files. This option is provided for use in debugging the compiler. --mmppcc--rreellaattiivvee--lliitteerraall--llooaaddss --mmnnoo--ppcc--rreellaattiivvee--lliitteerraall--llooaaddss Enable or disable PC-relative literal loads. With this option lit- eral pools are accessed using a single instruction and emitted af- ter each function. This limits the maximum size of functions to 1MB. This is enabled by default for --mmccmmooddeell==ttiinnyy. --mmssiiggnn--rreettuurrnn--aaddddrreessss==_s_c_o_p_e Select the function scope on which return address signing will be applied. Permissible values are nnoonnee, which disables return ad- dress signing, nnoonn--lleeaaff, which enables pointer signing for func- tions which are not leaf functions, and aallll, which enables pointer signing for all functions. The default value is nnoonnee. This option has been deprecated by -mbranch-protection. --mmbbrraanncchh--pprrootteeccttiioonn==_n_o_n_e||_s_t_a_n_d_a_r_d||_p_a_c_-_r_e_t[[++_l_e_a_f++_b_-_k_e_y]]||_b_t_i Select the branch protection features to use. nnoonnee is the default and turns off all types of branch protection. ssttaannddaarrdd turns on all types of branch protection features. If a feature has addi- tional tuning options, then ssttaannddaarrdd sets it to its standard level. ppaacc--rreett[[++_l_e_a_f]] turns on return address signing to its standard level: signing functions that save the return address to memory (non-leaf functions will practically always do this) using the a-key. The optional argument lleeaaff can be used to extend the sign- ing to include leaf functions. The optional argument bb--kkeeyy can be used to sign the functions with the B-key instead of the A-key. bbttii turns on branch target identification mechanism. --mmhhaarrddeenn--ssllss==_o_p_t_s Enable compiler hardening against straight line speculation (SLS). _o_p_t_s is a comma-separated list of the following options: rreettbbrr bbllrr In addition, --mmhhaarrddeenn--ssllss==aallll enables all SLS hardening while --mmhhaarrddeenn--ssllss==nnoonnee disables all SLS hardening. --mmssvvee--vveeccttoorr--bbiittss==_b_i_t_s Specify the number of bits in an SVE vector register. This option only has an effect when SVE is enabled. GCC supports two forms of SVE code generation: "vector-length ag- nostic" output that works with any size of vector register and "vector-length specific" output that allows GCC to make assumptions about the vector length when it is useful for optimization reasons. The possible values of bbiittss are: ssccaallaabbllee, 112288, 225566, 551122, 11002244 and 22004488. Specifying ssccaallaabbllee selects vector-length agnostic output. At present --mmssvvee--vveeccttoorr--bbiittss==112288 also generates vector-length ag- nostic output for big-endian targets. All other values generate vector-length specific code. The behavior of these values may change in future releases and no value except ssccaallaabbllee should be relied on for producing code that is portable across different hardware SVE vector lengths. The default is --mmssvvee--vveeccttoorr--bbiittss==ssccaallaabbllee, which produces vector- length agnostic code. --mmaarrcchh and --mmccppuu Feature Modifiers Feature modifiers used with --mmaarrcchh and --mmccppuu can be any of the follow- ing and their inverses nnoo_f_e_a_t_u_r_e: ccrrcc Enable CRC extension. This is on by default for --mmaarrcchh==aarrmmvv88..11--aa. ccrryyppttoo Enable Crypto extension. This also enables Advanced SIMD and floating-point instructions. ffpp Enable floating-point instructions. This is on by default for all possible values for options --mmaarrcchh and --mmccppuu. ssiimmdd Enable Advanced SIMD instructions. This also enables floating- point instructions. This is on by default for all possible values for options --mmaarrcchh and --mmccppuu. ssvvee Enable Scalable Vector Extension instructions. This also enables Advanced SIMD and floating-point instructions. llssee Enable Large System Extension instructions. This is on by default for --mmaarrcchh==aarrmmvv88..11--aa. rrddmmaa Enable Round Double Multiply Accumulate instructions. This is on by default for --mmaarrcchh==aarrmmvv88..11--aa. ffpp1166 Enable FP16 extension. This also enables floating-point instruc- tions. ffpp1166ffmmll Enable FP16 fmla extension. This also enables FP16 extensions and floating-point instructions. This option is enabled by default for --mmaarrcchh==aarrmmvv88..44--aa. Use of this option with architectures prior to Armv8.2-A is not supported. rrccppcc Enable the RcPc extension. This does not change code generation from GCC, but is passed on to the assembler, enabling inline asm statements to use instructions from the RcPc extension. ddoottpprroodd Enable the Dot Product extension. This also enables Advanced SIMD instructions. aaeess Enable the Armv8-a aes and pmull crypto extension. This also en- ables Advanced SIMD instructions. sshhaa22 Enable the Armv8-a sha2 crypto extension. This also enables Ad- vanced SIMD instructions. sshhaa33 Enable the sha512 and sha3 crypto extension. This also enables Ad- vanced SIMD instructions. Use of this option with architectures prior to Armv8.2-A is not supported. ssmm44 Enable the sm3 and sm4 crypto extension. This also enables Ad- vanced SIMD instructions. Use of this option with architectures prior to Armv8.2-A is not supported. pprrooffiillee Enable the Statistical Profiling extension. This option is only to enable the extension at the assembler level and does not affect code generation. rrnngg Enable the Armv8.5-a Random Number instructions. This option is only to enable the extension at the assembler level and does not affect code generation. mmeemmttaagg Enable the Armv8.5-a Memory Tagging Extensions. Use of this option with architectures prior to Armv8.5-A is not supported. ssbb Enable the Armv8-a Speculation Barrier instruction. This option is only to enable the extension at the assembler level and does not affect code generation. This option is enabled by default for --mmaarrcchh==aarrmmvv88..55--aa. ssssbbss Enable the Armv8-a Speculative Store Bypass Safe instruction. This option is only to enable the extension at the assembler level and does not affect code generation. This option is enabled by default for --mmaarrcchh==aarrmmvv88..55--aa. pprreeddrreess Enable the Armv8-a Execution and Data Prediction Restriction in- structions. This option is only to enable the extension at the as- sembler level and does not affect code generation. This option is enabled by default for --mmaarrcchh==aarrmmvv88..55--aa. ssvvee22 Enable the Armv8-a Scalable Vector Extension 2. This also enables SVE instructions. ssvvee22--bbiittppeerrmm Enable SVE2 bitperm instructions. This also enables SVE2 instruc- tions. ssvvee22--ssmm44 Enable SVE2 sm4 instructions. This also enables SVE2 instructions. ssvvee22--aaeess Enable SVE2 aes instructions. This also enables SVE2 instructions. ssvvee22--sshhaa33 Enable SVE2 sha3 instructions. This also enables SVE2 instruc- tions. ttmmee Enable the Transactional Memory Extension. ii88mmmm Enable 8-bit Integer Matrix Multiply instructions. This also en- ables Advanced SIMD and floating-point instructions. This option is enabled by default for --mmaarrcchh==aarrmmvv88..66--aa. Use of this option with architectures prior to Armv8.2-A is not supported. ff3322mmmm Enable 32-bit Floating point Matrix Multiply instructions. This also enables SVE instructions. Use of this option with architec- tures prior to Armv8.2-A is not supported. ff6644mmmm Enable 64-bit Floating point Matrix Multiply instructions. This also enables SVE instructions. Use of this option with architec- tures prior to Armv8.2-A is not supported. bbff1166 Enable brain half-precision floating-point instructions. This also enables Advanced SIMD and floating-point instructions. This option is enabled by default for --mmaarrcchh==aarrmmvv88..66--aa. Use of this option with architectures prior to Armv8.2-A is not supported. llss6644 Enable the 64-byte atomic load and store instructions for accelera- tors. This option is enabled by default for --mmaarrcchh==aarrmmvv88..77--aa. mmooppss Enable the instructions to accelerate memory operations like "mem- cpy", "memmove", "memset". This option is enabled by default for --mmaarrcchh==aarrmmvv88..88--aa ffllaaggmm Enable the Flag Manipulation instructions Extension. ppaauutthh Enable the Pointer Authentication Extension. Feature ccrryyppttoo implies aaeess, sshhaa22, and ssiimmdd, which implies ffpp. Con- versely, nnooffpp implies nnoossiimmdd, which implies nnooccrryyppttoo, nnooaaeess and nnoosshhaa22. _A_d_a_p_t_e_v_a _E_p_i_p_h_a_n_y _O_p_t_i_o_n_s These --mm options are defined for Adapteva Epiphany: --mmhhaallff--rreegg--ffiillee Don't allocate any register in the range "r32"..."r63". That al- lows code to run on hardware variants that lack these registers. --mmpprreeffeerr--sshhoorrtt--iinnssnn--rreeggss Preferentially allocate registers that allow short instruction gen- eration. This can result in increased instruction count, so this may either reduce or increase overall code size. --mmbbrraanncchh--ccoosstt==_n_u_m Set the cost of branches to roughly _n_u_m "simple" instructions. This cost is only a heuristic and is not guaranteed to produce con- sistent results across releases. --mmccmmoovvee Enable the generation of conditional moves. --mmnnooppss==_n_u_m Emit _n_u_m NOPs before every other generated instruction. --mmnnoo--ssoofftt--ccmmppssff For single-precision floating-point comparisons, emit an "fsub" in- struction and test the flags. This is faster than a software com- parison, but can get incorrect results in the presence of NaNs, or when two different small numbers are compared such that their dif- ference is calculated as zero. The default is --mmssoofftt--ccmmppssff, which uses slower, but IEEE-compliant, software comparisons. --mmssttaacckk--ooffffsseett==_n_u_m Set the offset between the top of the stack and the stack pointer. E.g., a value of 8 means that the eight bytes in the range "sp+0...sp+7" can be used by leaf functions without stack alloca- tion. Values other than 88 or 1166 are untested and unlikely to work. Note also that this option changes the ABI; compiling a program with a different stack offset than the libraries have been compiled with generally does not work. This option can be useful if you want to evaluate if a different stack offset would give you better code, but to actually use a different stack offset to build working programs, it is recommended to configure the toolchain with the ap- propriate ----wwiitthh--ssttaacckk--ooffffsseett==_n_u_m option. --mmnnoo--rroouunndd--nneeaarreesstt Make the scheduler assume that the rounding mode has been set to truncating. The default is --mmrroouunndd--nneeaarreesstt. --mmlloonngg--ccaallllss If not otherwise specified by an attribute, assume all calls might be beyond the offset range of the "b" / "bl" instructions, and therefore load the function address into a register before perform- ing a (otherwise direct) call. This is the default. --mmsshhoorrtt--ccaallllss If not otherwise specified by an attribute, assume all direct calls are in the range of the "b" / "bl" instructions, so use these in- structions for direct calls. The default is --mmlloonngg--ccaallllss. --mmssmmaallll1166 Assume addresses can be loaded as 16-bit unsigned values. This does not apply to function addresses for which --mmlloonngg--ccaallllss seman- tics are in effect. --mmffpp--mmooddee==_m_o_d_e Set the prevailing mode of the floating-point unit. This deter- mines the floating-point mode that is provided and expected at function call and return time. Making this mode match the mode you predominantly need at function start can make your programs smaller and faster by avoiding unnecessary mode switches. _m_o_d_e can be set to one the following values: ccaalllleerr Any mode at function entry is valid, and retained or restored when the function returns, and when it calls other functions. This mode is useful for compiling libraries or other compila- tion units you might want to incorporate into different pro- grams with different prevailing FPU modes, and the convenience of being able to use a single object file outweighs the size and speed overhead for any extra mode switching that might be needed, compared with what would be needed with a more specific choice of prevailing FPU mode. ttrruunnccaattee This is the mode used for floating-point calculations with truncating (i.e. round towards zero) rounding mode. That in- cludes conversion from floating point to integer. rroouunndd--nneeaarreesstt This is the mode used for floating-point calculations with round-to-nearest-or-even rounding mode. iinntt This is the mode used to perform integer calculations in the FPU, e.g. integer multiply, or integer multiply-and-accumu- late. The default is --mmffpp--mmooddee==ccaalllleerr --mmnnoo--sspplliitt--lloohhii --mmnnoo--ppoossttiinncc --mmnnoo--ppoossttmmooddiiffyy Code generation tweaks that disable, respectively, splitting of 32-bit loads, generation of post-increment addresses, and genera- tion of post-modify addresses. The defaults are mmsspplliitt--lloohhii, --mmppoosstt--iinncc, and --mmppoosstt--mmooddiiffyy. --mmnnoovveecctt--ddoouubbllee Change the preferred SIMD mode to SImode. The default is --mmvveecctt--ddoouubbllee, which uses DImode as preferred SIMD mode. --mmaaxx--vveecctt--aalliiggnn==_n_u_m The maximum alignment for SIMD vector mode types. _n_u_m may be 4 or 8. The default is 8. Note that this is an ABI change, even though many library function interfaces are unaffected if they don't use SIMD vector modes in places that affect size and/or alignment of relevant types. --mmsspplliitt--vveeccmmoovvee--eeaarrllyy Split vector moves into single word moves before reload. In theory this can give better register allocation, but so far the reverse seems to be generally the case. --mm11rreegg--_r_e_g Specify a register to hold the constant -1, which makes loading small negative constants and certain bitmasks faster. Allowable values for _r_e_g are rr4433 and rr6633, which specify use of that register as a fixed register, and nnoonnee, which means that no register is used for this purpose. The default is --mm11rreegg--nnoonnee. _A_M_D _G_C_N _O_p_t_i_o_n_s These options are defined specifically for the AMD GCN port. --mmaarrcchh==_g_p_u --mmttuunnee==_g_p_u Set architecture type or tuning for _g_p_u. Supported values for _g_p_u are ffiijjii Compile for GCN3 Fiji devices (gfx803). ggffxx990000 Compile for GCN5 Vega 10 devices (gfx900). ggffxx990066 Compile for GCN5 Vega 20 devices (gfx906). --mmssrraamm--eecccc==oonn --mmssrraamm--eecccc==ooffff --mmssrraamm--eecccc==aannyy Compile binaries suitable for devices with the SRAM-ECC feature en- abled, disabled, or either mode. This feature can be enabled per- process on some devices. The compiled code must match the device mode. The default is aannyy, for devices that support it. --mmssttaacckk--ssiizzee==_b_y_t_e_s Specify how many _b_y_t_e_s of stack space will be requested for each GPU thread (wave-front). Beware that there may be many threads and limited memory available. The size of the stack allocation may also have an impact on run-time performance. The default is 32KB when using OpenACC or OpenMP, and 1MB otherwise. --mmxxnnaacckk Compile binaries suitable for devices with the XNACK feature en- abled. Some devices always require XNACK and some allow the user to configure XNACK. The compiled code must match the device mode. The default is --mmnnoo--xxnnaacckk. At present this option is a placeholder for support that is not yet implemented. _A_R_C _O_p_t_i_o_n_s The following options control the architecture variant for which code is being compiled: --mmbbaarrrreell--sshhiifftteerr Generate instructions supported by barrel shifter. This is the de- fault unless --mmccppuu==AARRCC660011 or --mmccppuu==AARRCCEEMM is in effect. --mmjjllii--aallwwaayyss Force to call a function using jli_s instruction. This option is valid only for ARCv2 architecture. --mmccppuu==_c_p_u Set architecture type, register usage, and instruction scheduling parameters for _c_p_u. There are also shortcut alias options avail- able for backward compatibility and convenience. Supported values for _c_p_u are aarrcc660000 Compile for ARC600. Aliases: --mmAA66, --mmAARRCC660000. aarrcc660011 Compile for ARC601. Alias: --mmAARRCC660011. aarrcc770000 Compile for ARC700. Aliases: --mmAA77, --mmAARRCC770000. This is the de- fault when configured with ----wwiitthh--ccppuu==aarrcc770000. aarrcceemm Compile for ARC EM. aarrcchhss Compile for ARC HS. eemm Compile for ARC EM CPU with no hardware extensions. eemm44 Compile for ARC EM4 CPU. eemm44__ddmmiippss Compile for ARC EM4 DMIPS CPU. eemm44__ffppuuss Compile for ARC EM4 DMIPS CPU with the single-precision float- ing-point extension. eemm44__ffppuuddaa Compile for ARC EM4 DMIPS CPU with single-precision floating- point and double assist instructions. hhss Compile for ARC HS CPU with no hardware extensions except the atomic instructions. hhss3344 Compile for ARC HS34 CPU. hhss3388 Compile for ARC HS38 CPU. hhss3388__lliinnuuxx Compile for ARC HS38 CPU with all hardware extensions on. aarrcc660000__nnoorrmm Compile for ARC 600 CPU with "norm" instructions enabled. aarrcc660000__mmuull3322xx1166 Compile for ARC 600 CPU with "norm" and 32x16-bit multiply in- structions enabled. aarrcc660000__mmuull6644 Compile for ARC 600 CPU with "norm" and "mul64"-family instruc- tions enabled. aarrcc660011__nnoorrmm Compile for ARC 601 CPU with "norm" instructions enabled. aarrcc660011__mmuull3322xx1166 Compile for ARC 601 CPU with "norm" and 32x16-bit multiply in- structions enabled. aarrcc660011__mmuull6644 Compile for ARC 601 CPU with "norm" and "mul64"-family instruc- tions enabled. nnppss440000 Compile for ARC 700 on NPS400 chip. eemm__mmiinnii Compile for ARC EM minimalist configuration featuring reduced register set. --mmddppffpp --mmddppffpp--ccoommppaacctt Generate double-precision FPX instructions, tuned for the compact implementation. --mmddppffpp--ffaasstt Generate double-precision FPX instructions, tuned for the fast im- plementation. --mmnnoo--ddppffpp--llrrssrr Disable "lr" and "sr" instructions from using FPX extension aux registers. --mmeeaa Generate extended arithmetic instructions. Currently only "divaw", "adds", "subs", and "sat16" are supported. Only valid for --mmccppuu==AARRCC770000. --mmnnoo--mmppyy Do not generate "mpy"-family instructions for ARC700. This option is deprecated. --mmmmuull3322xx1166 Generate 32x16-bit multiply and multiply-accumulate instructions. --mmmmuull6644 Generate "mul64" and "mulu64" instructions. Only valid for --mmccppuu==AARRCC660000. --mmnnoorrmm Generate "norm" instructions. This is the default if --mmccppuu==AARRCC770000 is in effect. --mmssppffpp --mmssppffpp--ccoommppaacctt Generate single-precision FPX instructions, tuned for the compact implementation. --mmssppffpp--ffaasstt Generate single-precision FPX instructions, tuned for the fast im- plementation. --mmssiimmdd Enable generation of ARC SIMD instructions via target-specific builtins. Only valid for --mmccppuu==AARRCC770000. --mmssoofftt--ffllooaatt This option ignored; it is provided for compatibility purposes only. Software floating-point code is emitted by default, and this default can overridden by FPX options; --mmssppffpp, --mmssppffpp--ccoommppaacctt, or --mmssppffpp--ffaasstt for single precision, and --mmddppffpp, --mmddppffpp--ccoommppaacctt, or --mmddppffpp--ffaasstt for double precision. --mmsswwaapp Generate "swap" instructions. --mmaattoommiicc This enables use of the locked load/store conditional extension to implement atomic memory built-in functions. Not available for ARC 6xx or ARC EM cores. --mmddiivv--rreemm Enable "div" and "rem" instructions for ARCv2 cores. --mmccooddee--ddeennssiittyy Enable code density instructions for ARC EM. This option is on by default for ARC HS. --mmllll6644 Enable double load/store operations for ARC HS cores. --mmttpp--rreeggnnoo==_r_e_g_n_o Specify thread pointer register number. --mmmmppyy--ooppttiioonn==_m_u_l_t_o Compile ARCv2 code with a multiplier design option. You can spec- ify the option using either a string or numeric value for _m_u_l_t_o. wwllhh11 is the default value. The recognized values are: 00 nnoonnee No multiplier available. 11 ww 16x16 multiplier, fully pipelined. The following instructions are enabled: "mpyw" and "mpyuw". 22 wwllhh11 32x32 multiplier, fully pipelined (1 stage). The following in- structions are additionally enabled: "mpy", "mpyu", "mpym", "mpymu", and "mpy_s". 33 wwllhh22 32x32 multiplier, fully pipelined (2 stages). The following instructions are additionally enabled: "mpy", "mpyu", "mpym", "mpymu", and "mpy_s". 44 wwllhh33 Two 16x16 multipliers, blocking, sequential. The following in- structions are additionally enabled: "mpy", "mpyu", "mpym", "mpymu", and "mpy_s". 55 wwllhh44 One 16x16 multiplier, blocking, sequential. The following in- structions are additionally enabled: "mpy", "mpyu", "mpym", "mpymu", and "mpy_s". 66 wwllhh55 One 32x4 multiplier, blocking, sequential. The following in- structions are additionally enabled: "mpy", "mpyu", "mpym", "mpymu", and "mpy_s". 77 pplluuss__ddmmppyy ARC HS SIMD support. 88 pplluuss__mmaaccdd ARC HS SIMD support. 99 pplluuss__qqmmaaccww ARC HS SIMD support. This option is only available for ARCv2 cores. --mmffppuu==_f_p_u Enables support for specific floating-point hardware extensions for ARCv2 cores. Supported values for _f_p_u are: ffppuuss Enables support for single-precision floating-point hardware extensions. ffppuudd Enables support for double-precision floating-point hardware extensions. The single-precision floating-point extension is also enabled. Not available for ARC EM. ffppuuddaa Enables support for double-precision floating-point hardware extensions using double-precision assist instructions. The single-precision floating-point extension is also enabled. This option is only available for ARC EM. ffppuuddaa__ddiivv Enables support for double-precision floating-point hardware extensions using double-precision assist instructions. The single-precision floating-point, square-root, and divide exten- sions are also enabled. This option is only available for ARC EM. ffppuuddaa__ffmmaa Enables support for double-precision floating-point hardware extensions using double-precision assist instructions. The single-precision floating-point and fused multiply and add hardware extensions are also enabled. This option is only available for ARC EM. ffppuuddaa__aallll Enables support for double-precision floating-point hardware extensions using double-precision assist instructions. All single-precision floating-point hardware extensions are also enabled. This option is only available for ARC EM. ffppuuss__ddiivv Enables support for single-precision floating-point, square- root and divide hardware extensions. ffppuudd__ddiivv Enables support for double-precision floating-point, square- root and divide hardware extensions. This option includes op- tion ffppuuss__ddiivv. Not available for ARC EM. ffppuuss__ffmmaa Enables support for single-precision floating-point and fused multiply and add hardware extensions. ffppuudd__ffmmaa Enables support for double-precision floating-point and fused multiply and add hardware extensions. This option includes op- tion ffppuuss__ffmmaa. Not available for ARC EM. ffppuuss__aallll Enables support for all single-precision floating-point hard- ware extensions. ffppuudd__aallll Enables support for all single- and double-precision floating- point hardware extensions. Not available for ARC EM. --mmiirrqq--ccttrrll--ssaavveedd==_r_e_g_i_s_t_e_r_-_r_a_n_g_e,, _b_l_i_n_k,, _l_p___c_o_u_n_t Specifies general-purposes registers that the processor automati- cally saves/restores on interrupt entry and exit. _r_e_g_i_s_t_e_r_-_r_a_n_g_e is specified as two registers separated by a dash. The register range always starts with "r0", the upper limit is "fp" register. _b_l_i_n_k and _l_p___c_o_u_n_t are optional. This option is only valid for ARC EM and ARC HS cores. --mmrrggff--bbaannkkeedd--rreeggss==_n_u_m_b_e_r Specifies the number of registers replicated in second register bank on entry to fast interrupt. Fast interrupts are interrupts with the highest priority level P0. These interrupts save only PC and STATUS32 registers to avoid memory transactions during inter- rupt entry and exit sequences. Use this option when you are using fast interrupts in an ARC V2 family processor. Permitted values are 4, 8, 16, and 32. --mmllppcc--wwiiddtthh==_w_i_d_t_h Specify the width of the "lp_count" register. Valid values for _w_i_d_t_h are 8, 16, 20, 24, 28 and 32 bits. The default width is fixed to 32 bits. If the width is less than 32, the compiler does not attempt to transform loops in your program to use the zero-de- lay loop mechanism unless it is known that the "lp_count" register can hold the required loop-counter value. Depending on the width specified, the compiler and run-time library might continue to use the loop mechanism for various needs. This option defines macro "__ARC_LPC_WIDTH__" with the value of _w_i_d_t_h. --mmrrff1166 This option instructs the compiler to generate code for a 16-entry register file. This option defines the "__ARC_RF16__" preprocessor macro. --mmbbrraanncchh--iinnddeexx Enable use of "bi" or "bih" instructions to implement jump tables. The following options are passed through to the assembler, and also de- fine preprocessor macro symbols. --mmddsspp--ppaacckkaa Passed down to the assembler to enable the DSP Pack A extensions. Also sets the preprocessor symbol "__Xdsp_packa". This option is deprecated. --mmddvvbbff Passed down to the assembler to enable the dual Viterbi butterfly extension. Also sets the preprocessor symbol "__Xdvbf". This op- tion is deprecated. --mmlloocckk Passed down to the assembler to enable the locked load/store condi- tional extension. Also sets the preprocessor symbol "__Xlock". --mmmmaacc--dd1166 Passed down to the assembler. Also sets the preprocessor symbol "__Xxmac_d16". This option is deprecated. --mmmmaacc--2244 Passed down to the assembler. Also sets the preprocessor symbol "__Xxmac_24". This option is deprecated. --mmrrttsscc Passed down to the assembler to enable the 64-bit time-stamp counter extension instruction. Also sets the preprocessor symbol "__Xrtsc". This option is deprecated. --mmsswwaappee Passed down to the assembler to enable the swap byte ordering ex- tension instruction. Also sets the preprocessor symbol "__Xswape". --mmtteelleepphhoonnyy Passed down to the assembler to enable dual- and single-operand in- structions for telephony. Also sets the preprocessor symbol "__Xtelephony". This option is deprecated. --mmxxyy Passed down to the assembler to enable the XY memory extension. Also sets the preprocessor symbol "__Xxy". The following options control how the assembly code is annotated: --mmiissiizzee Annotate assembler instructions with estimated addresses. --mmaannnnoottaattee--aalliiggnn Explain what alignment considerations lead to the decision to make an instruction short or long. The following options are passed through to the linker: --mmaarrcclliinnuuxx Passed through to the linker, to specify use of the "arclinux" emu- lation. This option is enabled by default in tool chains built for "arc-linux-uclibc" and "arceb-linux-uclibc" targets when profiling is not requested. --mmaarrcclliinnuuxx__pprrooff Passed through to the linker, to specify use of the "arclinux_prof" emulation. This option is enabled by default in tool chains built for "arc-linux-uclibc" and "arceb-linux-uclibc" targets when pro- filing is requested. The following options control the semantics of generated code: --mmlloonngg--ccaallllss Generate calls as register indirect calls, thus providing access to the full 32-bit address range. --mmmmeeddiiuumm--ccaallllss Don't use less than 25-bit addressing range for calls, which is the offset available for an unconditional branch-and-link instruction. Conditional execution of function calls is suppressed, to allow use of the 25-bit range, rather than the 21-bit range with conditional branch-and-link. This is the default for tool chains built for "arc-linux-uclibc" and "arceb-linux-uclibc" targets. --GG _n_u_m Put definitions of externally-visible data in a small data section if that data is no bigger than _n_u_m bytes. The default value of _n_u_m is 4 for any ARC configuration, or 8 when we have double load/store operations. --mmnnoo--ssddaattaa Do not generate sdata references. This is the default for tool chains built for "arc-linux-uclibc" and "arceb-linux-uclibc" tar- gets. --mmvvoollaattiillee--ccaacchhee Use ordinarily cached memory accesses for volatile references. This is the default. --mmnnoo--vvoollaattiillee--ccaacchhee Enable cache bypass for volatile references. The following options fine tune code generation: --mmaalliiggnn--ccaallll Does nothing. Preserved for backward compatibility. --mmaauuttoo--mmooddiiffyy--rreegg Enable the use of pre/post modify with register displacement. --mmbbbbiitt--ppeeeepphhoollee Enable bbit peephole2. --mmnnoo--bbrrcccc This option disables a target-specific pass in _a_r_c___r_e_o_r_g to gener- ate compare-and-branch ("br_c_c_") instructions. It has no effect on generation of these instructions driven by the combiner pass. --mmccaassee--vveeccttoorr--ppccrreell Use PC-relative switch case tables to enable case table shortening. This is the default for --OOss. --mmccoommppaacctt--ccaasseessii Enable compact "casesi" pattern. This is the default for --OOss, and only available for ARCv1 cores. This option is deprecated. --mmnnoo--ccoonndd--eexxeecc Disable the ARCompact-specific pass to generate conditional execu- tion instructions. Due to delay slot scheduling and interactions between operand num- bers, literal sizes, instruction lengths, and the support for con- ditional execution, the target-independent pass to generate condi- tional execution is often lacking, so the ARC port has kept a spe- cial pass around that tries to find more conditional execution gen- eration opportunities after register allocation, branch shortening, and delay slot scheduling have been done. This pass generally, but not always, improves performance and code size, at the cost of ex- tra compilation time, which is why there is an option to switch it off. If you have a problem with call instructions exceeding their allowable offset range because they are conditionalized, you should consider using --mmmmeeddiiuumm--ccaallllss instead. --mmeeaarrllyy--ccbbrraanncchhssii Enable pre-reload use of the "cbranchsi" pattern. --mmeexxppaanndd--aaddddddii Expand "adddi3" and "subdi3" at RTL generation time into "add.f", "adc" etc. This option is deprecated. --mmiinnddeexxeedd--llooaaddss Enable the use of indexed loads. This can be problematic because some optimizers then assume that indexed stores exist, which is not the case. --mmllrraa Enable Local Register Allocation. This is still experimental for ARC, so by default the compiler uses standard reload (i.e. --mmnnoo--llrraa). --mmllrraa--pprriioorriittyy--nnoonnee Don't indicate any priority for target registers. --mmllrraa--pprriioorriittyy--ccoommppaacctt Indicate target register priority for r0..r3 / r12..r15. --mmllrraa--pprriioorriittyy--nnoonnccoommppaacctt Reduce target register priority for r0..r3 / r12..r15. --mmmmiilllliiccooddee When optimizing for size (using --OOss), prologues and epilogues that have to save or restore a large number of registers are often shortened by using call to a special function in libgcc; this is referred to as a _m_i_l_l_i_c_o_d_e call. As these calls can pose perfor- mance issues, and/or cause linking issues when linking in a non- standard way, this option is provided to turn on or off millicode call generation. --mmccooddee--ddeennssiittyy--ffrraammee This option enable the compiler to emit "enter" and "leave" in- structions. These instructions are only valid for CPUs with code- density feature. --mmmmiixxeedd--ccooddee Does nothing. Preserved for backward compatibility. --mmqq--ccllaassss Ths option is deprecated. Enable qq instruction alternatives. This is the default for --OOss. --mmRRccqq Enable RRccqq constraint handling. Most short code generation depends on this. This is the default. --mmRRccww Enable RRccww constraint handling. Most ccfsm condexec mostly depends on this. This is the default. --mmssiizzee--lleevveell==_l_e_v_e_l Fine-tune size optimization with regards to instruction lengths and alignment. The recognized values for _l_e_v_e_l are: 00 No size optimization. This level is deprecated and treated like 11. 11 Short instructions are used opportunistically. 22 In addition, alignment of loops and of code after barriers are dropped. 33 In addition, optional data alignment is dropped, and the option OOss is enabled. This defaults to 33 when --OOss is in effect. Otherwise, the behavior when this is not set is equivalent to level 11. --mmttuunnee==_c_p_u Set instruction scheduling parameters for _c_p_u, overriding any im- plied by --mmccppuu==. Supported values for _c_p_u are AARRCC660000 Tune for ARC600 CPU. AARRCC660011 Tune for ARC601 CPU. AARRCC770000 Tune for ARC700 CPU with standard multiplier block. AARRCC770000--xxmmaacc Tune for ARC700 CPU with XMAC block. AARRCC772255DD Tune for ARC725D CPU. AARRCC775500DD Tune for ARC750D CPU. --mmmmuullttccoosstt==_n_u_m Cost to assume for a multiply instruction, with 44 being equal to a normal instruction. --mmuunnaalliiggnn--pprroobb--tthhrreesshhoolldd==_p_r_o_b_a_b_i_l_i_t_y Does nothing. Preserved for backward compatibility. The following options are maintained for backward compatibility, but are now deprecated and will be removed in a future release: --mmaarrggoonnaauutt Obsolete FPX. --mmbbiigg--eennddiiaann --EEBB Compile code for big-endian targets. Use of these options is now deprecated. Big-endian code is supported by configuring GCC to build "arceb-elf32" and "arceb-linux-uclibc" targets, for which big endian is the default. --mmlliittttllee--eennddiiaann --EELL Compile code for little-endian targets. Use of these options is now deprecated. Little-endian code is supported by configuring GCC to build "arc-elf32" and "arc-linux-uclibc" targets, for which lit- tle endian is the default. --mmbbaarrrreell__sshhiifftteerr Replaced by --mmbbaarrrreell--sshhiifftteerr. --mmddppffpp__ccoommppaacctt Replaced by --mmddppffpp--ccoommppaacctt. --mmddppffpp__ffaasstt Replaced by --mmddppffpp--ffaasstt. --mmddsspp__ppaacckkaa Replaced by --mmddsspp--ppaacckkaa. --mmEEAA Replaced by --mmeeaa. --mmmmaacc__2244 Replaced by --mmmmaacc--2244. --mmmmaacc__dd1166 Replaced by --mmmmaacc--dd1166. --mmssppffpp__ccoommppaacctt Replaced by --mmssppffpp--ccoommppaacctt. --mmssppffpp__ffaasstt Replaced by --mmssppffpp--ffaasstt. --mmttuunnee==_c_p_u Values aarrcc660000, aarrcc660011, aarrcc770000 and aarrcc770000--xxmmaacc for _c_p_u are replaced by AARRCC660000, AARRCC660011, AARRCC770000 and AARRCC770000--xxmmaacc respectively. --mmuullttccoosstt==_n_u_m Replaced by --mmmmuullttccoosstt. _A_R_M _O_p_t_i_o_n_s These --mm options are defined for the ARM port: --mmaabbii==_n_a_m_e Generate code for the specified ABI. Permissible values are: aappccss-- ggnnuu, aattppccss, aaaappccss, aaaappccss--lliinnuuxx and iiwwmmmmxxtt. --mmaappccss--ffrraammee Generate a stack frame that is compliant with the ARM Procedure Call Standard for all functions, even if this is not strictly nec- essary for correct execution of the code. Specifying --ffoommiitt--ffrraammee--ppooiinntteerr with this option causes the stack frames not to be generated for leaf functions. The default is --mmnnoo--aappccss--ffrraammee. This option is deprecated. --mmaappccss This is a synonym for --mmaappccss--ffrraammee and is deprecated. --mmtthhuummbb--iinntteerrwwoorrkk Generate code that supports calling between the ARM and Thumb in- struction sets. Without this option, on pre-v5 architectures, the two instruction sets cannot be reliably used inside one program. The default is --mmnnoo--tthhuummbb--iinntteerrwwoorrkk, since slightly larger code is generated when --mmtthhuummbb--iinntteerrwwoorrkk is specified. In AAPCS configura- tions this option is meaningless. --mmnnoo--sscchheedd--pprroolloogg Prevent the reordering of instructions in the function prologue, or the merging of those instruction with the instructions in the func- tion's body. This means that all functions start with a recogniz- able set of instructions (or in fact one of a choice from a small set of different function prologues), and this information can be used to locate the start of functions inside an executable piece of code. The default is --mmsscchheedd--pprroolloogg. --mmffllooaatt--aabbii==_n_a_m_e Specifies which floating-point ABI to use. Permissible values are: ssoofftt, ssooffttffpp and hhaarrdd. Specifying ssoofftt causes GCC to generate output containing library calls for floating-point operations. ssooffttffpp allows the generation of code using hardware floating-point instructions, but still uses the soft-float calling conventions. hhaarrdd allows generation of floating-point instructions and uses FPU-specific calling conven- tions. The default depends on the specific target configuration. Note that the hard-float and soft-float ABIs are not link-compatible; you must compile your entire program with the same ABI, and link with a compatible set of libraries. --mmggeenneerraall--rreeggss--oonnllyy Generate code which uses only the general-purpose registers. This will prevent the compiler from using floating-point and Advanced SIMD registers but will not impose any restrictions on the assem- bler. --mmlliittttllee--eennddiiaann Generate code for a processor running in little-endian mode. This is the default for all standard configurations. --mmbbiigg--eennddiiaann Generate code for a processor running in big-endian mode; the de- fault is to compile code for a little-endian processor. --mmbbee88 --mmbbee3322 When linking a big-endian image select between BE8 and BE32 for- mats. The option has no effect for little-endian images and is ig- nored. The default is dependent on the selected target architec- ture. For ARMv6 and later architectures the default is BE8, for older architectures the default is BE32. BE32 format has been dep- recated by ARM. --mmaarrcchh==_n_a_m_e[++eexxtteennssiioonn......] This specifies the name of the target ARM architecture. GCC uses this name to determine what kind of instructions it can emit when generating assembly code. This option can be used in conjunction with or instead of the --mmccppuu== option. Permissible names are: aarrmmvv44tt, aarrmmvv55tt, aarrmmvv55ttee, aarrmmvv66, aarrmmvv66jj, aarrmmvv66kk, aarrmmvv66kkzz, aarrmmvv66tt22, aarrmmvv66zz, aarrmmvv66zzkk, aarrmmvv77, aarrmmvv77--aa, aarrmmvv77vvee, aarrmmvv88--aa, aarrmmvv88..11--aa, aarrmmvv88..22--aa, aarrmmvv88..33--aa, aarrmmvv88..44--aa, aarrmmvv88..55--aa, aarrmmvv88..66--aa, aarrmmvv99--aa, aarrmmvv77--rr, aarrmmvv88--rr, aarrmmvv66--mm, aarrmmvv66ss--mm, aarrmmvv77--mm, aarrmmvv77ee--mm, aarrmmvv88--mm..bbaassee, aarrmmvv88--mm..mmaaiinn, aarrmmvv88..11--mm..mmaaiinn, aarrmmvv99--aa, iiwwmm-- mmxxtt and iiwwmmmmxxtt22. Additionally, the following architectures, which lack support for the Thumb execution state, are recognized but support is depre- cated: aarrmmvv44. Many of the architectures support extensions. These can be added by appending ++_e_x_t_e_n_s_i_o_n to the architecture name. Extension op- tions are processed in order and capabilities accumulate. An ex- tension will also enable any necessary base extensions upon which it depends. For example, the ++ccrryyppttoo extension will always enable the ++ssiimmdd extension. The exception to the additive construction is for extensions that are prefixed with ++nnoo......: these extensions dis- able the specified option and any other extensions that may depend on the presence of that extension. For example, --mmaarrcchh==aarrmmvv77--aa++ssiimmdd++nnooffpp++vvffppvv44 is equivalent to writ- ing --mmaarrcchh==aarrmmvv77--aa++vvffppvv44 since the ++ssiimmdd option is entirely dis- abled by the ++nnooffpp option that follows it. Most extension names are generically named, but have an effect that is dependent upon the architecture to which it is applied. For ex- ample, the ++ssiimmdd option can be applied to both aarrmmvv77--aa and aarrmmvv88--aa architectures, but will enable the original ARMv7-A Advanced SIMD (Neon) extensions for aarrmmvv77--aa and the ARMv8-A variant for aarrmmvv88--aa. The table below lists the supported extensions for each architec- ture. Architectures not mentioned do not support any extensions. aarrmmvv55ttee aarrmmvv66 aarrmmvv66jj aarrmmvv66kk aarrmmvv66kkzz aarrmmvv66tt22 aarrmmvv66zz aarrmmvv66zzkk ++ffpp The VFPv2 floating-point instructions. The extension ++vvffppvv22 can be used as an alias for this extension. ++nnooffpp Disable the floating-point instructions. aarrmmvv77 The common subset of the ARMv7-A, ARMv7-R and ARMv7-M architec- tures. ++ffpp The VFPv3 floating-point instructions, with 16 double-pre- cision registers. The extension ++vvffppvv33--dd1166 can be used as an alias for this extension. Note that floating-point is not supported by the base ARMv7-M architecture, but is com- patible with both the ARMv7-A and ARMv7-R architectures. ++nnooffpp Disable the floating-point instructions. aarrmmvv77--aa ++mmpp The multiprocessing extension. ++sseecc The security extension. ++ffpp The VFPv3 floating-point instructions, with 16 double-pre- cision registers. The extension ++vvffppvv33--dd1166 can be used as an alias for this extension. ++ssiimmdd The Advanced SIMD (Neon) v1 and the VFPv3 floating-point instructions. The extensions ++nneeoonn and ++nneeoonn--vvffppvv33 can be used as aliases for this extension. ++vvffppvv33 The VFPv3 floating-point instructions, with 32 double-pre- cision registers. ++vvffppvv33--dd1166--ffpp1166 The VFPv3 floating-point instructions, with 16 double-pre- cision registers and the half-precision floating-point con- version operations. ++vvffppvv33--ffpp1166 The VFPv3 floating-point instructions, with 32 double-pre- cision registers and the half-precision floating-point con- version operations. ++vvffppvv44--dd1166 The VFPv4 floating-point instructions, with 16 double-pre- cision registers. ++vvffppvv44 The VFPv4 floating-point instructions, with 32 double-pre- cision registers. ++nneeoonn--ffpp1166 The Advanced SIMD (Neon) v1 and the VFPv3 floating-point instructions, with the half-precision floating-point con- version operations. ++nneeoonn--vvffppvv44 The Advanced SIMD (Neon) v2 and the VFPv4 floating-point instructions. ++nnoossiimmdd Disable the Advanced SIMD instructions (does not disable floating point). ++nnooffpp Disable the floating-point and Advanced SIMD instructions. aarrmmvv77vvee The extended version of the ARMv7-A architecture with support for virtualization. ++ffpp The VFPv4 floating-point instructions, with 16 double-pre- cision registers. The extension ++vvffppvv44--dd1166 can be used as an alias for this extension. ++ssiimmdd The Advanced SIMD (Neon) v2 and the VFPv4 floating-point instructions. The extension ++nneeoonn--vvffppvv44 can be used as an alias for this extension. ++vvffppvv33--dd1166 The VFPv3 floating-point instructions, with 16 double-pre- cision registers. ++vvffppvv33 The VFPv3 floating-point instructions, with 32 double-pre- cision registers. ++vvffppvv33--dd1166--ffpp1166 The VFPv3 floating-point instructions, with 16 double-pre- cision registers and the half-precision floating-point con- version operations. ++vvffppvv33--ffpp1166 The VFPv3 floating-point instructions, with 32 double-pre- cision registers and the half-precision floating-point con- version operations. ++vvffppvv44--dd1166 The VFPv4 floating-point instructions, with 16 double-pre- cision registers. ++vvffppvv44 The VFPv4 floating-point instructions, with 32 double-pre- cision registers. ++nneeoonn The Advanced SIMD (Neon) v1 and the VFPv3 floating-point instructions. The extension ++nneeoonn--vvffppvv33 can be used as an alias for this extension. ++nneeoonn--ffpp1166 The Advanced SIMD (Neon) v1 and the VFPv3 floating-point instructions, with the half-precision floating-point con- version operations. ++nnoossiimmdd Disable the Advanced SIMD instructions (does not disable floating point). ++nnooffpp Disable the floating-point and Advanced SIMD instructions. aarrmmvv88--aa ++ccrrcc The Cyclic Redundancy Check (CRC) instructions. ++ssiimmdd The ARMv8-A Advanced SIMD and floating-point instructions. ++ccrryyppttoo The cryptographic instructions. ++nnooccrryyppttoo Disable the cryptographic instructions. ++nnooffpp Disable the floating-point, Advanced SIMD and cryptographic instructions. ++ssbb Speculation Barrier Instruction. ++pprreeddrreess Execution and Data Prediction Restriction Instructions. aarrmmvv88..11--aa ++ssiimmdd The ARMv8.1-A Advanced SIMD and floating-point instruc- tions. ++ccrryyppttoo The cryptographic instructions. This also enables the Ad- vanced SIMD and floating-point instructions. ++nnooccrryyppttoo Disable the cryptographic instructions. ++nnooffpp Disable the floating-point, Advanced SIMD and cryptographic instructions. ++ssbb Speculation Barrier Instruction. ++pprreeddrreess Execution and Data Prediction Restriction Instructions. aarrmmvv88..22--aa aarrmmvv88..33--aa ++ffpp1166 The half-precision floating-point data processing instruc- tions. This also enables the Advanced SIMD and floating- point instructions. ++ffpp1166ffmmll The half-precision floating-point fmla extension. This also enables the half-precision floating-point extension and Advanced SIMD and floating-point instructions. ++ssiimmdd The ARMv8.1-A Advanced SIMD and floating-point instruc- tions. ++ccrryyppttoo The cryptographic instructions. This also enables the Ad- vanced SIMD and floating-point instructions. ++ddoottpprroodd Enable the Dot Product extension. This also enables Ad- vanced SIMD instructions. ++nnooccrryyppttoo Disable the cryptographic extension. ++nnooffpp Disable the floating-point, Advanced SIMD and cryptographic instructions. ++ssbb Speculation Barrier Instruction. ++pprreeddrreess Execution and Data Prediction Restriction Instructions. ++ii88mmmm 8-bit Integer Matrix Multiply instructions. This also en- ables Advanced SIMD and floating-point instructions. ++bbff1166 Brain half-precision floating-point instructions. This also enables Advanced SIMD and floating-point instructions. aarrmmvv88..44--aa ++ffpp1166 The half-precision floating-point data processing instruc- tions. This also enables the Advanced SIMD and floating- point instructions as well as the Dot Product extension and the half-precision floating-point fmla extension. ++ssiimmdd The ARMv8.3-A Advanced SIMD and floating-point instructions as well as the Dot Product extension. ++ccrryyppttoo The cryptographic instructions. This also enables the Ad- vanced SIMD and floating-point instructions as well as the Dot Product extension. ++nnooccrryyppttoo Disable the cryptographic extension. ++nnooffpp Disable the floating-point, Advanced SIMD and cryptographic instructions. ++ssbb Speculation Barrier Instruction. ++pprreeddrreess Execution and Data Prediction Restriction Instructions. ++ii88mmmm 8-bit Integer Matrix Multiply instructions. This also en- ables Advanced SIMD and floating-point instructions. ++bbff1166 Brain half-precision floating-point instructions. This also enables Advanced SIMD and floating-point instructions. aarrmmvv88..55--aa ++ffpp1166 The half-precision floating-point data processing instruc- tions. This also enables the Advanced SIMD and floating- point instructions as well as the Dot Product extension and the half-precision floating-point fmla extension. ++ssiimmdd The ARMv8.3-A Advanced SIMD and floating-point instructions as well as the Dot Product extension. ++ccrryyppttoo The cryptographic instructions. This also enables the Ad- vanced SIMD and floating-point instructions as well as the Dot Product extension. ++nnooccrryyppttoo Disable the cryptographic extension. ++nnooffpp Disable the floating-point, Advanced SIMD and cryptographic instructions. ++ii88mmmm 8-bit Integer Matrix Multiply instructions. This also en- ables Advanced SIMD and floating-point instructions. ++bbff1166 Brain half-precision floating-point instructions. This also enables Advanced SIMD and floating-point instructions. aarrmmvv88..66--aa ++ffpp1166 The half-precision floating-point data processing instruc- tions. This also enables the Advanced SIMD and floating- point instructions as well as the Dot Product extension and the half-precision floating-point fmla extension. ++ssiimmdd The ARMv8.3-A Advanced SIMD and floating-point instructions as well as the Dot Product extension. ++ccrryyppttoo The cryptographic instructions. This also enables the Ad- vanced SIMD and floating-point instructions as well as the Dot Product extension. ++nnooccrryyppttoo Disable the cryptographic extension. ++nnooffpp Disable the floating-point, Advanced SIMD and cryptographic instructions. ++ii88mmmm 8-bit Integer Matrix Multiply instructions. This also en- ables Advanced SIMD and floating-point instructions. ++bbff1166 Brain half-precision floating-point instructions. This also enables Advanced SIMD and floating-point instructions. aarrmmvv77--rr ++ffpp..sspp The single-precision VFPv3 floating-point instructions. The extension ++vvffppvv33xxdd can be used as an alias for this ex- tension. ++ffpp The VFPv3 floating-point instructions with 16 double-preci- sion registers. The extension +vfpv3-d16 can be used as an alias for this extension. ++vvffppvv33xxdd--dd1166--ffpp1166 The single-precision VFPv3 floating-point instructions with 16 double-precision registers and the half-precision float- ing-point conversion operations. ++vvffppvv33--dd1166--ffpp1166 The VFPv3 floating-point instructions with 16 double-preci- sion registers and the half-precision floating-point con- version operations. ++nnooffpp Disable the floating-point extension. ++iiddiivv The ARM-state integer division instructions. ++nnooiiddiivv Disable the ARM-state integer division extension. aarrmmvv77ee--mm ++ffpp The single-precision VFPv4 floating-point instructions. ++ffppvv55 The single-precision FPv5 floating-point instructions. ++ffpp..ddpp The single- and double-precision FPv5 floating-point in- structions. ++nnooffpp Disable the floating-point extensions. aarrmmvv88..11--mm..mmaaiinn ++ddsspp The DSP instructions. ++mmvvee The M-Profile Vector Extension (MVE) integer instructions. ++mmvvee..ffpp The M-Profile Vector Extension (MVE) integer and single precision floating-point instructions. ++ffpp The single-precision floating-point instructions. ++ffpp..ddpp The single- and double-precision floating-point instruc- tions. ++nnooffpp Disable the floating-point extension. ++ccddeeccpp00,, ++ccddeeccpp11,, ...... ,, ++ccddeeccpp77 Enable the Custom Datapath Extension (CDE) on selected co- processors according to the numbers given in the options in the range 0 to 7. aarrmmvv88--mm..mmaaiinn ++ddsspp The DSP instructions. ++nnooddsspp Disable the DSP extension. ++ffpp The single-precision floating-point instructions. ++ffpp..ddpp The single- and double-precision floating-point instruc- tions. ++nnooffpp Disable the floating-point extension. ++ccddeeccpp00,, ++ccddeeccpp11,, ...... ,, ++ccddeeccpp77 Enable the Custom Datapath Extension (CDE) on selected co- processors according to the numbers given in the options in the range 0 to 7. aarrmmvv88--rr ++ccrrcc The Cyclic Redundancy Check (CRC) instructions. ++ffpp..sspp The single-precision FPv5 floating-point instructions. ++ssiimmdd The ARMv8-A Advanced SIMD and floating-point instructions. ++ccrryyppttoo The cryptographic instructions. ++nnooccrryyppttoo Disable the cryptographic instructions. ++nnooffpp Disable the floating-point, Advanced SIMD and cryptographic instructions. --mmaarrcchh==nnaattiivvee causes the compiler to auto-detect the architecture of the build computer. At present, this feature is only supported on GNU/Linux, and not all architectures are recognized. If the auto-detect is unsuccessful the option has no effect. --mmttuunnee==_n_a_m_e This option specifies the name of the target ARM processor for which GCC should tune the performance of the code. For some ARM implementations better performance can be obtained by using this option. Permissible names are: aarrmm77ttddmmii, aarrmm77ttddmmii--ss, aarrmm771100tt, aarrmm772200tt, aarrmm774400tt, ssttrroonnggaarrmm, ssttrroonnggaarrmm111100, ssttrroonnggaarrmm11110000, ssttrroonn-- ggaarrmm11111100, aarrmm88, aarrmm881100, aarrmm99, aarrmm99ee, aarrmm992200, aarrmm992200tt, aarrmm992222tt, aarrmm994466ee--ss, aarrmm996666ee--ss, aarrmm996688ee--ss, aarrmm992266eejj--ss, aarrmm994400tt, aarrmm99ttddmmii, aarrmm1100ttddmmii, aarrmm11002200tt, aarrmm11002266eejj--ss, aarrmm1100ee, aarrmm11002200ee, aarrmm11002222ee, aarrmm11113366jj--ss, aarrmm11113366jjff--ss, mmppccoorree, mmppccoorreennoovvffpp, aarrmm11115566tt22--ss, aarrmm11115566tt22ff--ss, aarrmm11117766jjzz--ss, aarrmm11117766jjzzff--ss, ggeenneerriicc--aarrmmvv77--aa, ccoorr-- tteexx--aa55, ccoorrtteexx--aa77, ccoorrtteexx--aa88, ccoorrtteexx--aa99, ccoorrtteexx--aa1122, ccoorrtteexx--aa1155, ccoorrtteexx--aa1177, ccoorrtteexx--aa3322, ccoorrtteexx--aa3355, ccoorrtteexx--aa5533, ccoorrtteexx--aa5555, ccoorr-- tteexx--aa5577, ccoorrtteexx--aa7722, ccoorrtteexx--aa7733, ccoorrtteexx--aa7755, ccoorrtteexx--aa7766, ccoorr-- tteexx--aa7766aaee, ccoorrtteexx--aa7777, ccoorrtteexx--aa7788, ccoorrtteexx--aa7788aaee, ccoorrtteexx--aa7788cc, ccoorr-- tteexx--aa771100, aarreess, ccoorrtteexx--rr44, ccoorrtteexx--rr44ff, ccoorrtteexx--rr55, ccoorrtteexx--rr77, ccoorr-- tteexx--rr88, ccoorrtteexx--rr5522, ccoorrtteexx--rr5522pplluuss, ccoorrtteexx--mm00, ccoorrtteexx--mm00pplluuss, ccoorr-- tteexx--mm11, ccoorrtteexx--mm33, ccoorrtteexx--mm44, ccoorrtteexx--mm77, ccoorrtteexx--mm2233, ccoorrtteexx--mm3333, ccoorrtteexx--mm3355pp, ccoorrtteexx--mm5555, ccoorrtteexx--xx11, ccoorrtteexx--mm11..ssmmaallll--mmuullttiippllyy, ccoorr-- tteexx--mm00..ssmmaallll--mmuullttiippllyy, ccoorrtteexx--mm00pplluuss..ssmmaallll--mmuullttiippllyy, eexxyynnooss--mm11, mmaarrvveellll--ppjj44, nneeoovveerrssee--nn11, nneeoovveerrssee--nn22, nneeoovveerrssee--vv11, xxssccaallee, iiwwmmmmxxtt, iiwwmmmmxxtt22, eepp99331122, ffaa552266, ffaa662266, ffaa660066ttee, ffaa662266ttee, ffmmpp662266, ffaa772266ttee, xxggeennee11. Additionally, this option can specify that GCC should tune the per- formance of the code for a big.LITTLE system. Permissible names are: ccoorrtteexx--aa1155..ccoorrtteexx--aa77, ccoorrtteexx--aa1177..ccoorrtteexx--aa77, ccoorrtteexx--aa5577..ccoorr-- tteexx--aa5533, ccoorrtteexx--aa7722..ccoorrtteexx--aa5533, ccoorrtteexx--aa7722..ccoorrtteexx--aa3355, ccoorr-- tteexx--aa7733..ccoorrtteexx--aa5533, ccoorrtteexx--aa7755..ccoorrtteexx--aa5555, ccoorrtteexx--aa7766..ccoorrtteexx--aa5555. --mmttuunnee==ggeenneerriicc--_a_r_c_h specifies that GCC should tune the performance for a blend of processors within architecture _a_r_c_h. The aim is to generate code that run well on the current most popular processors, balancing between optimizations that benefit some CPUs in the range, and avoiding performance pitfalls of other CPUs. The ef- fects of this option may change in future GCC versions as CPU mod- els come and go. --mmttuunnee permits the same extension options as --mmccppuu, but the exten- sion options do not affect the tuning of the generated code. --mmttuunnee==nnaattiivvee causes the compiler to auto-detect the CPU of the build computer. At present, this feature is only supported on GNU/Linux, and not all architectures are recognized. If the auto- detect is unsuccessful the option has no effect. --mmccppuu==_n_a_m_e[++eexxtteennssiioonn......] This specifies the name of the target ARM processor. GCC uses this name to derive the name of the target ARM architecture (as if spec- ified by --mmaarrcchh) and the ARM processor type for which to tune for performance (as if specified by --mmttuunnee). Where this option is used in conjunction with --mmaarrcchh or --mmttuunnee, those options take precedence over the appropriate part of this option. Many of the supported CPUs implement optional architectural exten- sions. Where this is so the architectural extensions are normally enabled by default. If implementations that lack the extension ex- ist, then the extension syntax can be used to disable those exten- sions that have been omitted. For floating-point and Advanced SIMD (Neon) instructions, the settings of the options --mmffllooaatt--aabbii and --mmffppuu must also be considered: floating-point and Advanced SIMD in- structions will only be used if --mmffllooaatt--aabbii is not set to ssoofftt; and any setting of --mmffppuu other than aauuttoo will override the available floating-point and SIMD extension instructions. For example, ccoorrtteexx--aa99 can be found in three major configurations: integer only, with just a floating-point unit or with floating- point and Advanced SIMD. The default is to enable all the instruc- tions, but the extensions ++nnoossiimmdd and ++nnooffpp can be used to disable just the SIMD or both the SIMD and floating-point instructions re- spectively. Permissible names for this option are the same as those for --mmttuunnee. The following extension options are common to the listed CPUs: ++nnooddsspp Disable the DSP instructions on ccoorrtteexx--mm3333, ccoorrtteexx--mm3355pp. ++nnooffpp Disables the floating-point instructions on aarrmm99ee, aarrmm994466ee--ss, aarrmm996666ee--ss, aarrmm996688ee--ss, aarrmm1100ee, aarrmm11002200ee, aarrmm11002222ee, aarrmm992266eejj--ss, aarrmm11002266eejj--ss, ccoorrtteexx--rr55, ccoorrtteexx--rr77, ccoorrtteexx--rr88, ccoorrtteexx--mm44, ccoorr-- tteexx--mm77, ccoorrtteexx--mm3333 and ccoorrtteexx--mm3355pp. Disables the floating- point and SIMD instructions on ggeenneerriicc--aarrmmvv77--aa, ccoorrtteexx--aa55, ccoorr-- tteexx--aa77, ccoorrtteexx--aa88, ccoorrtteexx--aa99, ccoorrtteexx--aa1122, ccoorrtteexx--aa1155, ccoorr-- tteexx--aa1177, ccoorrtteexx--aa1155..ccoorrtteexx--aa77, ccoorrtteexx--aa1177..ccoorrtteexx--aa77, ccoorr-- tteexx--aa3322, ccoorrtteexx--aa3355, ccoorrtteexx--aa5533 and ccoorrtteexx--aa5555. ++nnooffpp..ddpp Disables the double-precision component of the floating-point instructions on ccoorrtteexx--rr55, ccoorrtteexx--rr77, ccoorrtteexx--rr88, ccoorrtteexx--rr5522, ccoorrtteexx--rr5522pplluuss and ccoorrtteexx--mm77. ++nnoossiimmdd Disables the SIMD (but not floating-point) instructions on ggeenneerriicc--aarrmmvv77--aa, ccoorrtteexx--aa55, ccoorrtteexx--aa77 and ccoorrtteexx--aa99. ++ccrryyppttoo Enables the cryptographic instructions on ccoorrtteexx--aa3322, ccoorr-- tteexx--aa3355, ccoorrtteexx--aa5533, ccoorrtteexx--aa5555, ccoorrtteexx--aa5577, ccoorrtteexx--aa7722, ccoorr-- tteexx--aa7733, ccoorrtteexx--aa7755, eexxyynnooss--mm11, xxggeennee11, ccoorrtteexx--aa5577..ccoorrtteexx--aa5533, ccoorrtteexx--aa7722..ccoorrtteexx--aa5533, ccoorrtteexx--aa7733..ccoorrtteexx--aa3355, ccoorrtteexx--aa7733..ccoorr-- tteexx--aa5533 and ccoorrtteexx--aa7755..ccoorrtteexx--aa5555. Additionally the ggeenneerriicc--aarrmmvv77--aa pseudo target defaults to VFPv3 with 16 double-precision registers. It supports the following ex- tension options: mmpp, sseecc, vvffppvv33--dd1166, vvffppvv33, vvffppvv33--dd1166--ffpp1166, vvffppvv33--ffpp1166, vvffppvv44--dd1166, vvffppvv44, nneeoonn, nneeoonn--vvffppvv33, nneeoonn--ffpp1166, nneeoonn--vvffppvv44. The meanings are the same as for the extensions to --mmaarrcchh==aarrmmvv77--aa. --mmccppuu==ggeenneerriicc--_a_r_c_h is also permissible, and is equivalent to --mmaarrcchh==_a_r_c_h --mmttuunnee==ggeenneerriicc--_a_r_c_h. See --mmttuunnee for more information. --mmccppuu==nnaattiivvee causes the compiler to auto-detect the CPU of the build computer. At present, this feature is only supported on GNU/Linux, and not all architectures are recognized. If the auto- detect is unsuccessful the option has no effect. --mmffppuu==_n_a_m_e This specifies what floating-point hardware (or hardware emulation) is available on the target. Permissible names are: aauuttoo, vvffppvv22, vvffppvv33, vvffppvv33--ffpp1166, vvffppvv33--dd1166, vvffppvv33--dd1166--ffpp1166, vvffppvv33xxdd, vvffppvv33xxdd--ffpp1166, nneeoonn--vvffppvv33, nneeoonn--ffpp1166, vvffppvv44, vvffppvv44--dd1166, ffppvv44--sspp--dd1166, nneeoonn--vvffppvv44, ffppvv55--dd1166, ffppvv55--sspp--dd1166, ffpp--aarrmmvv88, nneeoonn--ffpp--aarrmmvv88 and ccrryyppttoo--nneeoonn--ffpp--aarrmmvv88. Note that nneeoonn is an alias for nneeoonn--vvffppvv33 and vvffpp is an alias for vvffppvv22. The setting aauuttoo is the default and is special. It causes the com- piler to select the floating-point and Advanced SIMD instructions based on the settings of --mmccppuu and --mmaarrcchh. If the selected floating-point hardware includes the NEON extension (e.g. --mmffppuu==nneeoonn), note that floating-point operations are not gen- erated by GCC's auto-vectorization pass unless --ffuunnssaaffee--mmaatthh--ooppttii-- mmiizzaattiioonnss is also specified. This is because NEON hardware does not fully implement the IEEE 754 standard for floating-point arith- metic (in particular denormal values are treated as zero), so the use of NEON instructions may lead to a loss of precision. You can also set the fpu name at function level by using the "tar- get("fpu=")" function attributes or pragmas. --mmffpp1166--ffoorrmmaatt==_n_a_m_e Specify the format of the "__fp16" half-precision floating-point type. Permissible names are nnoonnee, iieeeeee, and aalltteerrnnaattiivvee; the de- fault is nnoonnee, in which case the "__fp16" type is not defined. --mmssttrruuccttuurree--ssiizzee--bboouunnddaarryy==_n The sizes of all structures and unions are rounded up to a multiple of the number of bits set by this option. Permissible values are 8, 32 and 64. The default value varies for different toolchains. For the COFF targeted toolchain the default value is 8. A value of 64 is only allowed if the underlying ABI supports it. Specifying a larger number can produce faster, more efficient code, but can also increase the size of the program. Different values are potentially incompatible. Code compiled with one value cannot necessarily expect to work with code or libraries compiled with an- other value, if they exchange information using structures or unions. This option is deprecated. --mmaabboorrtt--oonn--nnoorreettuurrnn Generate a call to the function "abort" at the end of a "noreturn" function. It is executed if the function tries to return. --mmlloonngg--ccaallllss --mmnnoo--lloonngg--ccaallllss Tells the compiler to perform function calls by first loading the address of the function into a register and then performing a sub- routine call on this register. This switch is needed if the target function lies outside of the 64-megabyte addressing range of the offset-based version of subroutine call instruction. Even if this switch is enabled, not all function calls are turned into long calls. The heuristic is that static functions, functions that have the "short_call" attribute, functions that are inside the scope of a "#pragma no_long_calls" directive, and functions whose definitions have already been compiled within the current compila- tion unit are not turned into long calls. The exceptions to this rule are that weak function definitions, functions with the "long_call" attribute or the "section" attribute, and functions that are within the scope of a "#pragma long_calls" directive are always turned into long calls. This feature is not enabled by default. Specifying --mmnnoo--lloonngg--ccaallllss restores the default behavior, as does placing the function calls within the scope of a "#pragma long_calls_off" directive. Note these switches have no effect on how the compiler generates code to handle function calls via function pointers. --mmssiinnggllee--ppiicc--bbaassee Treat the register used for PIC addressing as read-only, rather than loading it in the prologue for each function. The runtime system is responsible for initializing this register with an appro- priate value before execution begins. --mmppiicc--rreeggiisstteerr==_r_e_g Specify the register to be used for PIC addressing. For standard PIC base case, the default is any suitable register determined by compiler. For single PIC base case, the default is RR99 if target is EABI based or stack-checking is enabled, otherwise the default is RR1100. --mmppiicc--ddaattaa--iiss--tteexxtt--rreellaattiivvee Assume that the displacement between the text and data segments is fixed at static link time. This permits using PC-relative address- ing operations to access data known to be in the data segment. For non-VxWorks RTP targets, this option is enabled by default. When disabled on such targets, it will enable --mmssiinnggllee--ppiicc--bbaassee by de- fault. --mmppookkee--ffuunnccttiioonn--nnaammee Write the name of each function into the text section, directly preceding the function prologue. The generated code is similar to this: t0 .ascii "arm_poke_function_name", 0 .align t1 .word 0xff000000 + (t1 - t0) arm_poke_function_name mov ip, sp stmfd sp!, {fp, ip, lr, pc} sub fp, ip, #4 When performing a stack backtrace, code can inspect the value of "pc" stored at "fp + 0". If the trace function then looks at loca- tion "pc - 12" and the top 8 bits are set, then we know that there is a function name embedded immediately preceding this location and has length "((pc[-3]) & 0xff000000)". --mmtthhuummbb --mmaarrmm Select between generating code that executes in ARM and Thumb states. The default for most configurations is to generate code that executes in ARM state, but the default can be changed by con- figuring GCC with the ----wwiitthh--mmooddee==_s_t_a_t_e configure option. You can also override the ARM and Thumb mode for each function by using the "target("thumb")" and "target("arm")" function attributes or pragmas. --mmfflliipp--tthhuummbb Switch ARM/Thumb modes on alternating functions. This option is provided for regression testing of mixed Thumb/ARM code generation, and is not intended for ordinary use in compiling code. --mmttppccss--ffrraammee Generate a stack frame that is compliant with the Thumb Procedure Call Standard for all non-leaf functions. (A leaf function is one that does not call any other functions.) The default is --mmnnoo--ttppccss--ffrraammee. --mmttppccss--lleeaaff--ffrraammee Generate a stack frame that is compliant with the Thumb Procedure Call Standard for all leaf functions. (A leaf function is one that does not call any other functions.) The default is --mmnnoo--aappccss--lleeaaff--ffrraammee. --mmccaalllleeee--ssuuppeerr--iinntteerrwwoorrkkiinngg Gives all externally visible functions in the file being compiled an ARM instruction set header which switches to Thumb mode before executing the rest of the function. This allows these functions to be called from non-interworking code. This option is not valid in AAPCS configurations because interworking is enabled by default. --mmccaalllleerr--ssuuppeerr--iinntteerrwwoorrkkiinngg Allows calls via function pointers (including virtual functions) to execute correctly regardless of whether the target code has been compiled for interworking or not. There is a small overhead in the cost of executing a function pointer if this option is enabled. This option is not valid in AAPCS configurations because interwork- ing is enabled by default. --mmttpp==_n_a_m_e Specify the access model for the thread local storage pointer. The valid models are ssoofftt, which generates calls to "__aeabi_read_tp", ccpp1155, which fetches the thread pointer from "cp15" directly (sup- ported in the arm6k architecture), and aauuttoo, which uses the best available method for the selected processor. The default setting is aauuttoo. --mmttllss--ddiiaalleecctt==_d_i_a_l_e_c_t Specify the dialect to use for accessing thread local storage. Two _d_i_a_l_e_c_ts are supported---ggnnuu and ggnnuu22. The ggnnuu dialect selects the original GNU scheme for supporting local and global dynamic TLS models. The ggnnuu22 dialect selects the GNU descriptor scheme, which provides better performance for shared libraries. The GNU descrip- tor scheme is compatible with the original scheme, but does require new assembler, linker and library support. Initial and local exec TLS models are unaffected by this option and always use the origi- nal scheme. --mmwwoorrdd--rreellooccaattiioonnss Only generate absolute relocations on word-sized values (i.e. R_ARM_ABS32). This is enabled by default on targets (uClinux, Sym- bianOS) where the runtime loader imposes this restriction, and when --ffppiicc or --ffPPIICC is specified. This option conflicts with --mmssllooww--ffllaasshh--ddaattaa. --mmffiixx--ccoorrtteexx--mm33--llddrrdd Some Cortex-M3 cores can cause data corruption when "ldrd" instruc- tions with overlapping destination and base registers are used. This option avoids generating these instructions. This option is enabled by default when --mmccppuu==ccoorrtteexx--mm33 is specified. --mmffiixx--ccoorrtteexx--aa5577--aaeess--11774422009988 --mmnnoo--ffiixx--ccoorrtteexx--aa5577--aaeess--11774422009988 --mmffiixx--ccoorrtteexx--aa7722--aaeess--11665555443311 --mmnnoo--ffiixx--ccoorrtteexx--aa7722--aaeess--11665555443311 Enable (disable) mitigation for an erratum on Cortex-A57 and Cor- tex-A72 that affects the AES cryptographic instructions. This op- tion is enabled by default when either --mmccppuu==ccoorrtteexx--aa5577 or --mmccppuu==ccoorrtteexx--aa7722 is specified. --mmuunnaalliiggnneedd--aacccceessss --mmnnoo--uunnaalliiggnneedd--aacccceessss Enables (or disables) reading and writing of 16- and 32- bit values from addresses that are not 16- or 32- bit aligned. By default un- aligned access is disabled for all pre-ARMv6, all ARMv6-M and for ARMv8-M Baseline architectures, and enabled for all other architec- tures. If unaligned access is not enabled then words in packed data structures are accessed a byte at a time. The ARM attribute "Tag_CPU_unaligned_access" is set in the gener- ated object file to either true or false, depending upon the set- ting of this option. If unaligned access is enabled then the pre- processor symbol "__ARM_FEATURE_UNALIGNED" is also defined. --mmnneeoonn--ffoorr--6644bbiittss This option is deprecated and has no effect. --mmssllooww--ffllaasshh--ddaattaa Assume loading data from flash is slower than fetching instruction. Therefore literal load is minimized for better performance. This option is only supported when compiling for ARMv7 M-profile and off by default. It conflicts with --mmwwoorrdd--rreellooccaattiioonnss. --mmaassmm--ssyynnttaaxx--uunniiffiieedd Assume inline assembler is using unified asm syntax. The default is currently off which implies divided syntax. This option has no impact on Thumb2. However, this may change in future releases of GCC. Divided syntax should be considered deprecated. --mmrreessttrriicctt--iitt Restricts generation of IT blocks to conform to the rules of ARMv8-A. IT blocks can only contain a single 16-bit instruction from a select set of instructions. This option is on by default for ARMv8-A Thumb mode. --mmpprriinntt--ttuunnee--iinnffoo Print CPU tuning information as comment in assembler file. This is an option used only for regression testing of the compiler and not intended for ordinary use in compiling code. This option is dis- abled by default. --mmvveerrbboossee--ccoosstt--dduummpp Enable verbose cost model dumping in the debug dump files. This option is provided for use in debugging the compiler. --mmppuurree--ccooddee Do not allow constant data to be placed in code sections. Addi- tionally, when compiling for ELF object format give all text sec- tions the ELF processor-specific section attribute "SHF_ARM_PURE- CODE". This option is only available when generating non-pic code for M-profile targets. --mmccmmssee Generate secure code as per the "ARMv8-M Security Extensions: Re- quirements on Development Tools Engineering Specification", which can be found on . --mmffiixx--ccmmssee--ccvvee--22002211--3355446655 Mitigate against a potential security issue with the "VLLDM" in- struction in some M-profile devices when using CMSE (CVE-2021-365465). This option is enabled by default when the op- tion --mmccppuu== is used with "cortex-m33", "cortex-m35p" or "cor- tex-m55". The option --mmnnoo--ffiixx--ccmmssee--ccvvee--22002211--3355446655 can be used to disable the mitigation. --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd==_g_u_a_r_d --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ooffffsseett==_o_f_f_s_e_t Generate stack protection code using canary at _g_u_a_r_d. Supported locations are gglloobbaall for a global canary or ttllss for a canary acces- sible via the TLS register. The option --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ooffff-- sseett== is for use with --ffssttaacckk--pprrootteeccttoorr--gguuaarrdd==ttllss and not for use in user-land code. --mmffddppiicc --mmnnoo--ffddppiicc Select the FDPIC ABI, which uses 64-bit function descriptors to represent pointers to functions. When the compiler is configured for "arm-*-uclinuxfdpiceabi" targets, this option is on by default and implies --ffPPIIEE if none of the PIC/PIE-related options is pro- vided. On other targets, it only enables the FDPIC-specific code generation features, and the user should explicitly provide the PIC/PIE-related options as needed. Note that static linking is not supported because it would still involve the dynamic linker when the program self-relocates. If such behavior is acceptable, use -static and -Wl,-dynamic-linker options. The opposite --mmnnoo--ffddppiicc option is useful (and required) to build the Linux kernel using the same ("arm-*-uclinuxfdpiceabi") toolchain as the one used to build the userland programs. _A_V_R _O_p_t_i_o_n_s These options are defined for AVR implementations: --mmmmccuu==_m_c_u Specify Atmel AVR instruction set architectures (ISA) or MCU type. The default for this option is aavvrr22. GCC supports the following AVR devices and ISAs: "avr2" "Classic" devices with up to 8 KiB of program memory. _m_c_u = "attiny22", "attiny26", "at90s2313", "at90s2323", "at90s2333", "at90s2343", "at90s4414", "at90s4433", "at90s4434", "at90c8534", "at90s8515", "at90s8535". "avr25" "Classic" devices with up to 8 KiB of program memory and with the "MOVW" instruction. _m_c_u = "attiny13", "attiny13a", "at- tiny24", "attiny24a", "attiny25", "attiny261", "attiny261a", "attiny2313", "attiny2313a", "attiny43u", "attiny44", "at- tiny44a", "attiny45", "attiny48", "attiny441", "attiny461", "attiny461a", "attiny4313", "attiny84", "attiny84a", "at- tiny85", "attiny87", "attiny88", "attiny828", "attiny841", "at- tiny861", "attiny861a", "ata5272", "ata6616c", "at86rf401". "avr3" "Classic" devices with 16 KiB up to 64 KiB of program memory. _m_c_u = "at76c711", "at43usb355". "avr31" "Classic" devices with 128 KiB of program memory. _m_c_u = "at- mega103", "at43usb320". "avr35" "Classic" devices with 16 KiB up to 64 KiB of program memory and with the "MOVW" instruction. _m_c_u = "attiny167", "at- tiny1634", "atmega8u2", "atmega16u2", "atmega32u2", "ata5505", "ata6617c", "ata664251", "at90usb82", "at90usb162". "avr4" "Enhanced" devices with up to 8 KiB of program memory. _m_c_u = "atmega48", "atmega48a", "atmega48p", "atmega48pa", "at- mega48pb", "atmega8", "atmega8a", "atmega8hva", "atmega88", "atmega88a", "atmega88p", "atmega88pa", "atmega88pb", "at- mega8515", "atmega8535", "ata6285", "ata6286", "ata6289", "ata6612c", "at90pwm1", "at90pwm2", "at90pwm2b", "at90pwm3", "at90pwm3b", "at90pwm81". "avr5" "Enhanced" devices with 16 KiB up to 64 KiB of program memory. _m_c_u = "atmega16", "atmega16a", "atmega16hva", "atmega16hva2", "atmega16hvb", "atmega16hvbrevb", "atmega16m1", "atmega16u4", "atmega161", "atmega162", "atmega163", "atmega164a", "at- mega164p", "atmega164pa", "atmega165", "atmega165a", "at- mega165p", "atmega165pa", "atmega168", "atmega168a", "at- mega168p", "atmega168pa", "atmega168pb", "atmega169", "at- mega169a", "atmega169p", "atmega169pa", "atmega32", "at- mega32a", "atmega32c1", "atmega32hvb", "atmega32hvbrevb", "at- mega32m1", "atmega32u4", "atmega32u6", "atmega323", "at- mega324a", "atmega324p", "atmega324pa", "atmega324pb", "at- mega325", "atmega325a", "atmega325p", "atmega325pa", "at- mega328", "atmega328p", "atmega328pb", "atmega329", "at- mega329a", "atmega329p", "atmega329pa", "atmega3250", "at- mega3250a", "atmega3250p", "atmega3250pa", "atmega3290", "at- mega3290a", "atmega3290p", "atmega3290pa", "atmega406", "at- mega64", "atmega64a", "atmega64c1", "atmega64hve", "at- mega64hve2", "atmega64m1", "atmega64rfr2", "atmega640", "at- mega644", "atmega644a", "atmega644p", "atmega644pa", "at- mega644rfr2", "atmega645", "atmega645a", "atmega645p", "at- mega649", "atmega649a", "atmega649p", "atmega6450", "at- mega6450a", "atmega6450p", "atmega6490", "atmega6490a", "at- mega6490p", "ata5795", "ata5790", "ata5790n", "ata5791", "ata6613c", "ata6614q", "ata5782", "ata5831", "ata8210", "ata8510", "ata5702m322", "at90pwm161", "at90pwm216", "at90pwm316", "at90can32", "at90can64", "at90scr100", "at90usb646", "at90usb647", "at94k", "m3000". "avr51" "Enhanced" devices with 128 KiB of program memory. _m_c_u = "at- mega128", "atmega128a", "atmega128rfa1", "atmega128rfr2", "at- mega1280", "atmega1281", "atmega1284", "atmega1284p", "at- mega1284rfr2", "at90can128", "at90usb1286", "at90usb1287". "avr6" "Enhanced" devices with 3-byte PC, i.e. with more than 128 KiB of program memory. _m_c_u = "atmega256rfr2", "atmega2560", "at- mega2561", "atmega2564rfr2". "avrxmega2" "XMEGA" devices with more than 8 KiB and up to 64 KiB of pro- gram memory. _m_c_u = "atxmega8e5", "atxmega16a4", "atxmega16a4u", "atxmega16c4", "atxmega16d4", "atxmega16e5", "atxmega32a4", "atxmega32a4u", "atxmega32c3", "atxmega32c4", "atxmega32d3", "atxmega32d4", "atxmega32e5". "avrxmega3" "XMEGA" devices with up to 64 KiB of combined program memory and RAM, and with program memory visible in the RAM address space. _m_c_u = "attiny202", "attiny204", "attiny212", "at- tiny214", "attiny402", "attiny404", "attiny406", "attiny412", "attiny414", "attiny416", "attiny417", "attiny804", "at- tiny806", "attiny807", "attiny814", "attiny816", "attiny817", "attiny1604", "attiny1606", "attiny1607", "attiny1614", "at- tiny1616", "attiny1617", "attiny3214", "attiny3216", "at- tiny3217", "atmega808", "atmega809", "atmega1608", "at- mega1609", "atmega3208", "atmega3209", "atmega4808", "at- mega4809". "avrxmega4" "XMEGA" devices with more than 64 KiB and up to 128 KiB of pro- gram memory. _m_c_u = "atxmega64a3", "atxmega64a3u", "atxmega64a4u", "atxmega64b1", "atxmega64b3", "atxmega64c3", "atxmega64d3", "atxmega64d4". "avrxmega5" "XMEGA" devices with more than 64 KiB and up to 128 KiB of pro- gram memory and more than 64 KiB of RAM. _m_c_u = "atxmega64a1", "atxmega64a1u". "avrxmega6" "XMEGA" devices with more than 128 KiB of program memory. _m_c_u = "atxmega128a3", "atxmega128a3u", "atxmega128b1", "atxmega128b3", "atxmega128c3", "atxmega128d3", "atxmega128d4", "atxmega192a3", "atxmega192a3u", "atxmega192c3", "atxmega192d3", "atxmega256a3", "atxmega256a3b", "atxmega256a3bu", "atxmega256a3u", "atxmega256c3", "atxmega256d3", "atxmega384c3", "atxmega384d3". "avrxmega7" "XMEGA" devices with more than 128 KiB of program memory and more than 64 KiB of RAM. _m_c_u = "atxmega128a1", "atxmega128a1u", "atxmega128a4u". "avrtiny" "TINY" Tiny core devices with 512 B up to 4 KiB of program mem- ory. _m_c_u = "attiny4", "attiny5", "attiny9", "attiny10", "at- tiny20", "attiny40". "avr1" This ISA is implemented by the minimal AVR core and supported for assembler only. _m_c_u = "attiny11", "attiny12", "attiny15", "attiny28", "at90s1200". --mmaabbssddaattaa Assume that all data in static storage can be accessed by LDS / STS instructions. This option has only an effect on reduced Tiny de- vices like ATtiny40. See also the "absdata" AAVVRR VVaarriiaabbllee AAtt-- ttrriibbuutteess,,vvaarriiaabbllee aattttrriibbuuttee. --mmaaccccuummuullaattee--aarrggss Accumulate outgoing function arguments and acquire/release the needed stack space for outgoing function arguments once in function prologue/epilogue. Without this option, outgoing arguments are pushed before calling a function and popped afterwards. Popping the arguments after the function call can be expensive on AVR so that accumulating the stack space might lead to smaller exe- cutables because arguments need not be removed from the stack after such a function call. This option can lead to reduced code size for functions that per- form several calls to functions that get their arguments on the stack like calls to printf-like functions. --mmbbrraanncchh--ccoosstt==_c_o_s_t Set the branch costs for conditional branch instructions to _c_o_s_t. Reasonable values for _c_o_s_t are small, non-negative integers. The default branch cost is 0. --mmccaallll--pprroolloogguueess Functions prologues/epilogues are expanded as calls to appropriate subroutines. Code size is smaller. --mmddoouubbllee==_b_i_t_s --mmlloonngg--ddoouubbllee==_b_i_t_s Set the size (in bits) of the "double" or "long double" type, re- spectively. Possible values for _b_i_t_s are 32 and 64. Whether or not a specific value for _b_i_t_s is allowed depends on the "--with-double=" and "--with-long-double=" configure options ("https://gcc.gnu.org/install/configure.html#avr"), and the same applies for the default values of the options. --mmggaass--iissrr--pprroolloogguueess Interrupt service routines (ISRs) may use the "__gcc_isr" pseudo instruction supported by GNU Binutils. If this option is on, the feature can still be disabled for individual ISRs by means of the AAVVRR FFuunnccttiioonn AAttttrriibbuutteess,,,,""nnoo__ggcccciissrr"" function attribute. This fea- ture is activated per default if optimization is on (but not with --OOgg, @pxref{Optimize Options}), and if GNU Binutils support PR21683 ("https://sourceware.org/PR21683"). --mmiinntt88 Assume "int" to be 8-bit integer. This affects the sizes of all types: a "char" is 1 byte, an "int" is 1 byte, a "long" is 2 bytes, and "long long" is 4 bytes. Please note that this option does not conform to the C standards, but it results in smaller code size. --mmmmaaiinn--iiss--OOSS__ttaasskk Do not save registers in "main". The effect is the same like at- taching attribute AAVVRR FFuunnccttiioonn AAttttrriibbuutteess,,,,""OOSS__ttaasskk"" to "main". It is activated per default if optimization is on. --mmnn--ffllaasshh==_n_u_m Assume that the flash memory has a size of _n_u_m times 64 KiB. --mmnnoo--iinntteerrrruuppttss Generated code is not compatible with hardware interrupts. Code size is smaller. --mmrreellaaxx Try to replace "CALL" resp. "JMP" instruction by the shorter "RCALL" resp. "RJMP" instruction if applicable. Setting --mmrreellaaxx just adds the ----mmlliinnkk--rreellaaxx option to the assembler's command line and the ----rreellaaxx option to the linker's command line. Jump relaxing is performed by the linker because jump offsets are not known before code is located. Therefore, the assembler code generated by the compiler is the same, but the instructions in the executable may differ from instructions in the assembler code. Relaxing must be turned on if linker stubs are needed, see the sec- tion on "EIND" and linker stubs below. --mmrrmmww Assume that the device supports the Read-Modify-Write instructions "XCH", "LAC", "LAS" and "LAT". --mmsshhoorrtt--ccaallllss Assume that "RJMP" and "RCALL" can target the whole program memory. This option is used internally for multilib selection. It is not an optimization option, and you don't need to set it by hand. --mmsspp88 Treat the stack pointer register as an 8-bit register, i.e. assume the high byte of the stack pointer is zero. In general, you don't need to set this option by hand. This option is used internally by the compiler to select and build multilibs for architectures "avr2" and "avr25". These architec- tures mix devices with and without "SPH". For any setting other than --mmmmccuu==aavvrr22 or --mmmmccuu==aavvrr2255 the compiler driver adds or removes this option from the compiler proper's command line, because the compiler then knows if the device or architecture has an 8-bit stack pointer and thus no "SPH" register or not. --mmssttrriicctt--XX Use address register "X" in a way proposed by the hardware. This means that "X" is only used in indirect, post-increment or pre- decrement addressing. Without this option, the "X" register may be used in the same way as "Y" or "Z" which then is emulated by additional instructions. For example, loading a value with "X+const" addressing with a small non-negative "const < 64" to a register _R_n is performed as adiw r26, const ; X += const ld , X ; = *X sbiw r26, const ; X -= const --mmttiinnyy--ssttaacckk Only change the lower 8 bits of the stack pointer. --mmffrraacctt--ccoonnvveerrtt--ttrruunnccaattee Allow to use truncation instead of rounding towards zero for frac- tional fixed-point types. --nnooddeevviicceelliibb Don't link against AVR-LibC's device specific library "lib.a". --nnooddeevviicceessppeeccss Don't add --ssppeeccss==ddeevviiccee--ssppeeccss//ssppeeccss--_m_c_u to the compiler driver's command line. The user takes responsibility for supplying the sub- processes like compiler proper, assembler and linker with appropri- ate command line options. This means that the user has to supply her private device specs file by means of --ssppeeccss==_p_a_t_h_-_t_o_-_s_p_e_c_s_- _f_i_l_e. There is no more need for option --mmmmccuu==_m_c_u. This option can also serve as a replacement for the older way of specifying custom device-specs files that needed --BB _s_o_m_e_-_p_a_t_h to point to a directory which contains a folder named "device-specs" which contains a specs file named "specs-_m_c_u_", where _m_c_u was speci- fied by --mmmmccuu==_m_c_u. --WWaaddddrr--ssppaaccee--ccoonnvveerrtt Warn about conversions between address spaces in the case where the resulting address space is not contained in the incoming address space. --WWmmiissssppeelllleedd--iissrr Warn if the ISR is misspelled, i.e. without __vector prefix. En- abled by default. "EIND" and Devices with More Than 128 Ki Bytes of Flash Pointers in the implementation are 16 bits wide. The address of a function or label is represented as word address so that indirect jumps and calls can target any code address in the range of 64 Ki words. In order to facilitate indirect jump on devices with more than 128 Ki bytes of program memory space, there is a special function register called "EIND" that serves as most significant part of the target ad- dress when "EICALL" or "EIJMP" instructions are used. Indirect jumps and calls on these devices are handled as follows by the compiler and are subject to some limitations: * The compiler never sets "EIND". * The compiler uses "EIND" implicitly in "EICALL"/"EIJMP" instruc- tions or might read "EIND" directly in order to emulate an indirect call/jump by means of a "RET" instruction. * The compiler assumes that "EIND" never changes during the startup code or during the application. In particular, "EIND" is not saved/restored in function or interrupt service routine pro- logue/epilogue. * For indirect calls to functions and computed goto, the linker gen- erates _s_t_u_b_s. Stubs are jump pads sometimes also called _t_r_a_m_p_o_- _l_i_n_e_s. Thus, the indirect call/jump jumps to such a stub. The stub contains a direct jump to the desired address. * Linker relaxation must be turned on so that the linker generates the stubs correctly in all situations. See the compiler option --mmrreellaaxx and the linker option ----rreellaaxx. There are corner cases where the linker is supposed to generate stubs but aborts without relaxation and without a helpful error message. * The default linker script is arranged for code with "EIND = 0". If code is supposed to work for a setup with "EIND != 0", a custom linker script has to be used in order to place the sections whose name start with ".trampolines" into the segment where "EIND" points to. * The startup code from libgcc never sets "EIND". Notice that startup code is a blend of code from libgcc and AVR-LibC. For the impact of AVR-LibC on "EIND", see the AVR-LibC user manual ("http://nongnu.org/avr-libc/user-manual/"). * It is legitimate for user-specific startup code to set up "EIND" early, for example by means of initialization code located in sec- tion ".init3". Such code runs prior to general startup code that initializes RAM and calls constructors, but after the bit of startup code from AVR-LibC that sets "EIND" to the segment where the vector table is located. #include static void __attribute__((section(".init3"),naked,used,no_instrument_function)) init3_set_eind (void) { __asm volatile ("ldi r24,pm_hh8(__trampolines_start)\n\t" "out %i0,r24" :: "n" (&EIND) : "r24","memory"); } The "__trampolines_start" symbol is defined in the linker script. * Stubs are generated automatically by the linker if the following two conditions are met: - (short for _g_e_n_e_r_a_t_e _s_t_u_b_s) like so: LDI r24, lo8(gs()) LDI r25, hi8(gs()) - _o_u_t_s_i_d_e the segment where the stubs are located. * The compiler emits such "gs" modifiers for code labels in the fol- lowing situations: - - - command-line option. - tables you can specify the --ffnnoo--jjuummpp--ttaabblleess command-line op- tion. - - * Jumping to non-symbolic addresses like so is _n_o_t supported: int main (void) { /* Call function at word address 0x2 */ return ((int(*)(void)) 0x2)(); } Instead, a stub has to be set up, i.e. the function has to be called through a symbol ("func_4" in the example): int main (void) { extern int func_4 (void); /* Call function at byte address 0x4 */ return func_4(); } and the application be linked with --WWll,,----ddeeffssyymm,,ffuunncc__44==00xx44. Alter- natively, "func_4" can be defined in the linker script. Handling of the "RAMPD", "RAMPX", "RAMPY" and "RAMPZ" Special Function Registers Some AVR devices support memories larger than the 64 KiB range that can be accessed with 16-bit pointers. To access memory locations outside this 64 KiB range, the content of a "RAMP" register is used as high part of the address: The "X", "Y", "Z" address register is concatenated with the "RAMPX", "RAMPY", "RAMPZ" special function register, respec- tively, to get a wide address. Similarly, "RAMPD" is used together with direct addressing. * The startup code initializes the "RAMP" special function registers with zero. * If a AAVVRR NNaammeedd AAddddrreessss SSppaacceess,,nnaammeedd aaddddrreessss ssppaaccee other than generic or "__flash" is used, then "RAMPZ" is set as needed before the operation. * If the device supports RAM larger than 64 KiB and the compiler needs to change "RAMPZ" to accomplish an operation, "RAMPZ" is re- set to zero after the operation. * If the device comes with a specific "RAMP" register, the ISR pro- logue/epilogue saves/restores that SFR and initializes it with zero in case the ISR code might (implicitly) use it. * RAM larger than 64 KiB is not supported by GCC for AVR targets. If you use inline assembler to read from locations outside the 16-bit address range and change one of the "RAMP" registers, you must re- set it to zero after the access. AVR Built-in Macros GCC defines several built-in macros so that the user code can test for the presence or absence of features. Almost any of the following built-in macros are deduced from device capabilities and thus triggered by the --mmmmccuu== command-line option. For even more AVR-specific built-in macros see AAVVRR NNaammeedd AAddddrreessss SSppaacceess and AAVVRR BBuuiilltt--iinn FFuunnccttiioonnss. "__AVR_ARCH__" Build-in macro that resolves to a decimal number that identifies the architecture and depends on the --mmmmccuu==_m_c_u option. Possible values are: 2, 25, 3, 31, 35, 4, 5, 51, 6 for _m_c_u="avr2", "avr25", "avr3", "avr31", "avr35", "avr4", "avr5", "avr51", "avr6", respectively and 100, 102, 103, 104, 105, 106, 107 for _m_c_u="avrtiny", "avrxmega2", "avrxmega3", "avrxmega4", "avrxmega5", "avrxmega6", "avrxmega7", respectively. If _m_c_u speci- fies a device, this built-in macro is set accordingly. For example, with --mmmmccuu==aattmmeeggaa88 the macro is defined to 4. "__AVR__D_e_v_i_c_e_____" Setting --mmmmccuu==_d_e_v_i_c_e defines this built-in macro which reflects the device's name. For example, --mmmmccuu==aattmmeeggaa88 defines the built-in macro "__AVR_ATmega8__", --mmmmccuu==aattttiinnyy226611aa defines "__AVR_AT- tiny261A__", etc. The built-in macros' names follow the scheme "__AVR__D_e_v_i_c_e_____" where _D_e_v_i_c_e is the device name as from the AVR user manual. The differ- ence between _D_e_v_i_c_e in the built-in macro and _d_e_v_i_c_e in --mmmmccuu==_d_e_- _v_i_c_e is that the latter is always lowercase. If _d_e_v_i_c_e is not a device but only a core architecture like aavvrr5511, this macro is not defined. "__AVR_DEVICE_NAME__" Setting --mmmmccuu==_d_e_v_i_c_e defines this built-in macro to the device's name. For example, with --mmmmccuu==aattmmeeggaa88 the macro is defined to "at- mega8". If _d_e_v_i_c_e is not a device but only a core architecture like aavvrr5511, this macro is not defined. "__AVR_XMEGA__" The device / architecture belongs to the XMEGA family of devices. "__AVR_HAVE_ELPM__" The device has the "ELPM" instruction. "__AVR_HAVE_ELPMX__" The device has the "ELPM R_n_,_Z_" and "ELPM R_n_,_Z_+_" instructions. "__AVR_HAVE_MOVW__" The device has the "MOVW" instruction to perform 16-bit register- register moves. "__AVR_HAVE_LPMX__" The device has the "LPM R_n_,_Z_" and "LPM R_n_,_Z_+_" instructions. "__AVR_HAVE_MUL__" The device has a hardware multiplier. "__AVR_HAVE_JMP_CALL__" The device has the "JMP" and "CALL" instructions. This is the case for devices with more than 8 KiB of program memory. "__AVR_HAVE_EIJMP_EICALL__" "__AVR_3_BYTE_PC__" The device has the "EIJMP" and "EICALL" instructions. This is the case for devices with more than 128 KiB of program memory. This also means that the program counter (PC) is 3 bytes wide. "__AVR_2_BYTE_PC__" The program counter (PC) is 2 bytes wide. This is the case for de- vices with up to 128 KiB of program memory. "__AVR_HAVE_8BIT_SP__" "__AVR_HAVE_16BIT_SP__" The stack pointer (SP) register is treated as 8-bit respectively 16-bit register by the compiler. The definition of these macros is affected by --mmttiinnyy--ssttaacckk. "__AVR_HAVE_SPH__" "__AVR_SP8__" The device has the SPH (high part of stack pointer) special func- tion register or has an 8-bit stack pointer, respectively. The definition of these macros is affected by --mmmmccuu== and in the cases of --mmmmccuu==aavvrr22 and --mmmmccuu==aavvrr2255 also by --mmsspp88. "__AVR_HAVE_RAMPD__" "__AVR_HAVE_RAMPX__" "__AVR_HAVE_RAMPY__" "__AVR_HAVE_RAMPZ__" The device has the "RAMPD", "RAMPX", "RAMPY", "RAMPZ" special func- tion register, respectively. "__NO_INTERRUPTS__" This macro reflects the --mmnnoo--iinntteerrrruuppttss command-line option. "__AVR_ERRATA_SKIP__" "__AVR_ERRATA_SKIP_JMP_CALL__" Some AVR devices (AT90S8515, ATmega103) must not skip 32-bit in- structions because of a hardware erratum. Skip instructions are "SBRS", "SBRC", "SBIS", "SBIC" and "CPSE". The second macro is only defined if "__AVR_HAVE_JMP_CALL__" is also set. "__AVR_ISA_RMW__" The device has Read-Modify-Write instructions (XCH, LAC, LAS and LAT). "__AVR_SFR_OFFSET__=_o_f_f_s_e_t_" Instructions that can address I/O special function registers di- rectly like "IN", "OUT", "SBI", etc. may use a different address as if addressed by an instruction to access RAM like "LD" or "STS". This offset depends on the device architecture and has to be sub- tracted from the RAM address in order to get the respective I/O ad- dress. "__AVR_SHORT_CALLS__" The --mmsshhoorrtt--ccaallllss command line option is set. "__AVR_PM_BASE_ADDRESS__=_a_d_d_r_" Some devices support reading from flash memory by means of "LD*" instructions. The flash memory is seen in the data address space at an offset of "__AVR_PM_BASE_ADDRESS__". If this macro is not defined, this feature is not available. If defined, the address space is linear and there is no need to put ".rodata" into RAM. This is handled by the default linker description file, and is cur- rently available for "avrtiny" and "avrxmega3". Even more conve- nient, there is no need to use address spaces like "__flash" or features like attribute "progmem" and "pgm_read_*". "__WITH_AVRLIBC__" The compiler is configured to be used together with AVR-Libc. See the ----wwiitthh--aavvrrlliibbcc configure option. "__HAVE_DOUBLE_MULTILIB__" Defined if --mmddoouubbllee== acts as a multilib option. "__HAVE_DOUBLE32__" "__HAVE_DOUBLE64__" Defined if the compiler supports 32-bit double resp. 64-bit double. The actual layout is specified by option --mmddoouubbllee==. "__DEFAULT_DOUBLE__" The size in bits of "double" if --mmddoouubbllee== is not set. To test the layout of "double" in a program, use the built-in macro "__SIZEOF_DOUBLE__". "__HAVE_LONG_DOUBLE32__" "__HAVE_LONG_DOUBLE64__" "__HAVE_LONG_DOUBLE_MULTILIB__" "__DEFAULT_LONG_DOUBLE__" Same as above, but for "long double" instead of "double". "__WITH_DOUBLE_COMPARISON__" Reflects the "--with-double-comparison={tristate|bool|libf7}" con- figure option ("https://gcc.gnu.org/install/configure.html#avr") and is defined to 2 or 3. "__WITH_LIBF7_LIBGCC__" "__WITH_LIBF7_MATH__" "__WITH_LIBF7_MATH_SYMBOLS__" Reflects the "--with-libf7={libgcc|math|math-symbols}" config- ure option ("https://gcc.gnu.org/install/configure.html#avr"). _B_l_a_c_k_f_i_n _O_p_t_i_o_n_s --mmccppuu==_c_p_u[--_s_i_r_e_v_i_s_i_o_n] Specifies the name of the target Blackfin processor. Currently, _c_p_u can be one of bbff551122, bbff551144, bbff551166, bbff551188, bbff552222, bbff552233, bbff552244, bbff552255, bbff552266, bbff552277, bbff553311, bbff553322, bbff553333, bbff553344, bbff553366, bbff553377, bbff553388, bbff553399, bbff554422, bbff554444, bbff554477, bbff554488, bbff554499, bbff554422mm, bbff554444mm, bbff554477mm, bbff554488mm, bbff554499mm, bbff556611, bbff559922. The optional _s_i_r_e_v_i_s_i_o_n specifies the silicon revision of the tar- get Blackfin processor. Any workarounds available for the targeted silicon revision are enabled. If _s_i_r_e_v_i_s_i_o_n is nnoonnee, no work- arounds are enabled. If _s_i_r_e_v_i_s_i_o_n is aannyy, all workarounds for the targeted processor are enabled. The "__SILICON_REVISION__" macro is defined to two hexadecimal digits representing the major and mi- nor numbers in the silicon revision. If _s_i_r_e_v_i_s_i_o_n is nnoonnee, the "__SILICON_REVISION__" is not defined. If _s_i_r_e_v_i_s_i_o_n is aannyy, the "__SILICON_REVISION__" is defined to be 0xffff. If this optional _s_i_r_e_v_i_s_i_o_n is not used, GCC assumes the latest known silicon revi- sion of the targeted Blackfin processor. GCC defines a preprocessor macro for the specified _c_p_u. For the bbffiinn--eellff toolchain, this option causes the hardware BSP provided by libgloss to be linked in if --mmssiimm is not given. Without this option, bbff553322 is used as the processor by default. Note that support for bbff556611 is incomplete. For bbff556611, only the preprocessor macro is defined. --mmssiimm Specifies that the program will be run on the simulator. This causes the simulator BSP provided by libgloss to be linked in. This option has effect only for bbffiinn--eellff toolchain. Certain other options, such as --mmiidd--sshhaarreedd--lliibbrraarryy and --mmffddppiicc, imply --mmssiimm. --mmoommiitt--lleeaaff--ffrraammee--ppooiinntteerr Don't keep the frame pointer in a register for leaf functions. This avoids the instructions to save, set up and restore frame pointers and makes an extra register available in leaf functions. --mmssppeecclldd--aannoommaallyy When enabled, the compiler ensures that the generated code does not contain speculative loads after jump instructions. If this option is used, "__WORKAROUND_SPECULATIVE_LOADS" is defined. --mmnnoo--ssppeecclldd--aannoommaallyy Don't generate extra code to prevent speculative loads from occur- ring. --mmccssyynncc--aannoommaallyy When enabled, the compiler ensures that the generated code does not contain CSYNC or SSYNC instructions too soon after conditional branches. If this option is used, "__WORKAROUND_SPECULATIVE_SYNCS" is defined. --mmnnoo--ccssyynncc--aannoommaallyy Don't generate extra code to prevent CSYNC or SSYNC instructions from occurring too soon after a conditional branch. --mmllooww6644kk When enabled, the compiler is free to take advantage of the knowl- edge that the entire program fits into the low 64k of memory. --mmnnoo--llooww6644kk Assume that the program is arbitrarily large. This is the default. --mmssttaacckk--cchheecckk--ll11 Do stack checking using information placed into L1 scratchpad mem- ory by the uClinux kernel. --mmiidd--sshhaarreedd--lliibbrraarryy Generate code that supports shared libraries via the library ID method. This allows for execute in place and shared libraries in an environment without virtual memory management. This option im- plies --ffPPIICC. With a bbffiinn--eellff target, this option implies --mmssiimm. --mmnnoo--iidd--sshhaarreedd--lliibbrraarryy Generate code that doesn't assume ID-based shared libraries are be- ing used. This is the default. --mmlleeaaff--iidd--sshhaarreedd--lliibbrraarryy Generate code that supports shared libraries via the library ID method, but assumes that this library or executable won't link against any other ID shared libraries. That allows the compiler to use faster code for jumps and calls. --mmnnoo--lleeaaff--iidd--sshhaarreedd--lliibbrraarryy Do not assume that the code being compiled won't link against any ID shared libraries. Slower code is generated for jump and call insns. --mmsshhaarreedd--lliibbrraarryy--iidd==nn Specifies the identification number of the ID-based shared library being compiled. Specifying a value of 0 generates more compact code; specifying other values forces the allocation of that number to the current library but is no more space- or time-efficient than omitting this option. --mmsseepp--ddaattaa Generate code that allows the data segment to be located in a dif- ferent area of memory from the text segment. This allows for exe- cute in place in an environment without virtual memory management by eliminating relocations against the text section. --mmnnoo--sseepp--ddaattaa Generate code that assumes that the data segment follows the text segment. This is the default. --mmlloonngg--ccaallllss --mmnnoo--lloonngg--ccaallllss Tells the compiler to perform function calls by first loading the address of the function into a register and then performing a sub- routine call on this register. This switch is needed if the target function lies outside of the 24-bit addressing range of the offset- based version of subroutine call instruction. This feature is not enabled by default. Specifying --mmnnoo--lloonngg--ccaallllss restores the default behavior. Note these switches have no effect on how the compiler generates code to handle function calls via function pointers. --mmffaasstt--ffpp Link with the fast floating-point library. This library relaxes some of the IEEE floating-point standard's rules for checking in- puts against Not-a-Number (NAN), in the interest of performance. --mmiinnlliinnee--pplltt Enable inlining of PLT entries in function calls to functions that are not known to bind locally. It has no effect without --mmffddppiicc. --mmmmuullttiiccoorree Build a standalone application for multicore Blackfin processors. This option causes proper start files and link scripts supporting multicore to be used, and defines the macro "__BFIN_MULTICORE". It can only be used with --mmccppuu==bbff556611[--_s_i_r_e_v_i_s_i_o_n]. This option can be used with --mmccoorreeaa or --mmccoorreebb, which selects the one-application-per-core programming model. Without --mmccoorreeaa or --mmccoorreebb, the single-application/dual-core programming model is used. In this model, the main function of Core B should be named as "coreb_main". If this option is not used, the single-core application programming model is used. --mmccoorreeaa Build a standalone application for Core A of BF561 when using the one-application-per-core programming model. Proper start files and link scripts are used to support Core A, and the macro "__BFIN_COREA" is defined. This option can only be used in con- junction with --mmmmuullttiiccoorree. --mmccoorreebb Build a standalone application for Core B of BF561 when using the one-application-per-core programming model. Proper start files and link scripts are used to support Core B, and the macro "__BFIN_COREB" is defined. When this option is used, "coreb_main" should be used instead of "main". This option can only be used in conjunction with --mmmmuullttiiccoorree. --mmssddrraamm Build a standalone application for SDRAM. Proper start files and link scripts are used to put the application into SDRAM, and the macro "__BFIN_SDRAM" is defined. The loader should initialize SDRAM before loading the application. --mmiiccppllbb Assume that ICPLBs are enabled at run time. This has an effect on certain anomaly workarounds. For Linux targets, the default is to assume ICPLBs are enabled; for standalone applications the default is off. _C_6_X _O_p_t_i_o_n_s --mmaarrcchh==_n_a_m_e This specifies the name of the target architecture. GCC uses this name to determine what kind of instructions it can emit when gener- ating assembly code. Permissible names are: cc6622xx, cc6644xx, cc6644xx++, cc6677xx, cc6677xx++, cc667744xx. --mmbbiigg--eennddiiaann Generate code for a big-endian target. --mmlliittttllee--eennddiiaann Generate code for a little-endian target. This is the default. --mmssiimm Choose startup files and linker script suitable for the simulator. --mmssddaattaa==ddeeffaauulltt Put small global and static data in the ".neardata" section, which is pointed to by register "B14". Put small uninitialized global and static data in the ".bss" section, which is adjacent to the ".neardata" section. Put small read-only data into the ".rodata" section. The corresponding sections used for large pieces of data are ".fardata", ".far" and ".const". --mmssddaattaa==aallll Put all data, not just small objects, into the sections reserved for small data, and use addressing relative to the "B14" register to access them. --mmssddaattaa==nnoonnee Make no use of the sections reserved for small data, and use abso- lute addresses to access all data. Put all initialized global and static data in the ".fardata" section, and all uninitialized data in the ".far" section. Put all constant data into the ".const" section. _C_R_I_S _O_p_t_i_o_n_s These options are defined specifically for the CRIS ports. --mmaarrcchh==_a_r_c_h_i_t_e_c_t_u_r_e_-_t_y_p_e --mmccppuu==_a_r_c_h_i_t_e_c_t_u_r_e_-_t_y_p_e Generate code for the specified architecture. The choices for _a_r_- _c_h_i_t_e_c_t_u_r_e_-_t_y_p_e are vv33, vv88 and vv1100 for respectively ETRAX 4, ETRAX 100, and ETRAX 100 LX. Default is vv00. --mmttuunnee==_a_r_c_h_i_t_e_c_t_u_r_e_-_t_y_p_e Tune to _a_r_c_h_i_t_e_c_t_u_r_e_-_t_y_p_e everything applicable about the generated code, except for the ABI and the set of available instructions. The choices for _a_r_c_h_i_t_e_c_t_u_r_e_-_t_y_p_e are the same as for --mmaarrcchh==_a_r_c_h_i_- _t_e_c_t_u_r_e_-_t_y_p_e. --mmmmaaxx--ssttaacckk--ffrraammee==_n Warn when the stack frame of a function exceeds _n bytes. --mmeettrraaxx44 --mmeettrraaxx110000 The options --mmeettrraaxx44 and --mmeettrraaxx110000 are synonyms for --mmaarrcchh==vv33 and --mmaarrcchh==vv88 respectively. --mmmmuull--bbuugg--wwoorrkkaarroouunndd --mmnnoo--mmuull--bbuugg--wwoorrkkaarroouunndd Work around a bug in the "muls" and "mulu" instructions for CPU models where it applies. This option is disabled by default. --mmppddeebbuugg Enable CRIS-specific verbose debug-related information in the as- sembly code. This option also has the effect of turning off the ##NNOO__AAPPPP formatted-code indicator to the assembler at the beginning of the assembly file. --mmcccc--iinniitt Do not use condition-code results from previous instruction; always emit compare and test instructions before use of condition codes. --mmnnoo--ssiiddee--eeffffeeccttss Do not emit instructions with side effects in addressing modes other than post-increment. --mmssttaacckk--aalliiggnn --mmnnoo--ssttaacckk--aalliiggnn --mmddaattaa--aalliiggnn --mmnnoo--ddaattaa--aalliiggnn --mmccoonnsstt--aalliiggnn --mmnnoo--ccoonnsstt--aalliiggnn These options (nnoo-- options) arrange (eliminate arrangements) for the stack frame, individual data and constants to be aligned for the maximum single data access size for the chosen CPU model. The default is to arrange for 32-bit alignment. ABI details such as structure layout are not affected by these options. --mm3322--bbiitt --mm1166--bbiitt --mm88--bbiitt Similar to the stack- data- and const-align options above, these options arrange for stack frame, writable data and constants to all be 32-bit, 16-bit or 8-bit aligned. The default is 32-bit align- ment. --mmnnoo--pprroolloogguuee--eeppiilloogguuee --mmpprroolloogguuee--eeppiilloogguuee With --mmnnoo--pprroolloogguuee--eeppiilloogguuee, the normal function prologue and epi- logue which set up the stack frame are omitted and no return in- structions or return sequences are generated in the code. Use this option only together with visual inspection of the compiled code: no warnings or errors are generated when call-saved registers must be saved, or storage for local variables needs to be allocated. --mmeellff Legacy no-op option. --ssiimm This option arranges to link with input-output functions from a simulator library. Code, initialized data and zero-initialized data are allocated consecutively. --ssiimm22 Like --ssiimm, but pass linker options to locate initialized data at 0x40000000 and zero-initialized data at 0x80000000. _C_R_1_6 _O_p_t_i_o_n_s These options are defined specifically for the CR16 ports. --mmmmaacc Enable the use of multiply-accumulate instructions. Disabled by de- fault. --mmccrr1166ccpplluuss --mmccrr1166cc Generate code for CR16C or CR16C+ architecture. CR16C+ architecture is default. --mmssiimm Links the library libsim.a which is in compatible with simulator. Applicable to ELF compiler only. --mmiinntt3322 Choose integer type as 32-bit wide. --mmbbiitt--ooppss Generates "sbit"/"cbit" instructions for bit manipulations. --mmddaattaa--mmooddeell==_m_o_d_e_l Choose a data model. The choices for _m_o_d_e_l are nneeaarr, ffaarr or mmeeddiiuumm. mmeeddiiuumm is default. However, ffaarr is not valid with --mmccrr1166cc, as the CR16C architecture does not support the far data model. _C_-_S_K_Y _O_p_t_i_o_n_s GCC supports these options when compiling for C-SKY V2 processors. --mmaarrcchh==_a_r_c_h Specify the C-SKY target architecture. Valid values for _a_r_c_h are: cckk880011, cckk880022, cckk880033, cckk880077, and cckk881100. The default is cckk881100. --mmccppuu==_c_p_u Specify the C-SKY target processor. Valid values for _c_p_u are: cckk880011, cckk880011tt, cckk880022, cckk880022tt, cckk880022jj, cckk880033, cckk880033hh, cckk880033tt, cckk880033hhtt, cckk880033ff, cckk880033ffhh, cckk880033ee, cckk880033eehh, cckk880033eett, cckk880033eehhtt, cckk880033eeff, cckk880033eeffhh, cckk880033fftt, cckk880033eefftt, cckk880033eeffhhtt, cckk880033rr11, cckk880033hhrr11, cckk880033ttrr11, cckk880033hhttrr11, cckk880033ffrr11, cckk880033ffhhrr11, cckk880033eerr11, cckk880033eehhrr11, cckk880033eettrr11, cckk880033eehhttrr11, cckk880033eeffrr11, cckk880033eeffhhrr11, cckk880033ffttrr11, cckk880033eeffttrr11, cckk880033eeffhhttrr11, cckk880033ss, cckk880033sstt, cckk880033ssee, cckk880033ssff, cckk880033sseeff, cckk880033sseefftt, cckk880077ee, cckk880077eeff, cckk880077, cckk880077ff, cckk881100ee, cckk881100eett, cckk881100eeff, cckk881100eefftt, cckk881100, cckk881100vv, cckk881100ff, cckk881100tt, cckk881100ffvv, cckk881100ttvv, cckk881100fftt, and cckk881100ffttvv. --mmbbiigg--eennddiiaann --EEBB --mmlliittttllee--eennddiiaann --EELL Select big- or little-endian code. The default is little-endian. --mmffllooaatt--aabbii==_n_a_m_e Specifies which floating-point ABI to use. Permissible values are: ssoofftt, ssooffttffpp and hhaarrdd. Specifying ssoofftt causes GCC to generate output containing library calls for floating-point operations. ssooffttffpp allows the generation of code using hardware floating-point instructions, but still uses the soft-float calling conventions. hhaarrdd allows generation of floating-point instructions and uses FPU-specific calling conven- tions. The default depends on the specific target configuration. Note that the hard-float and soft-float ABIs are not link-compatible; you must compile your entire program with the same ABI, and link with a compatible set of libraries. --mmhhaarrdd--ffllooaatt --mmssoofftt--ffllooaatt Select hardware or software floating-point implementations. The default is soft float. --mmddoouubbllee--ffllooaatt --mmnnoo--ddoouubbllee--ffllooaatt When --mmhhaarrdd--ffllooaatt is in effect, enable generation of double-preci- sion float instructions. This is the default except when compiling for CK803. --mmffddiivvdduu --mmnnoo--ffddiivvdduu When --mmhhaarrdd--ffllooaatt is in effect, enable generation of "frecipd", "fsqrtd", and "fdivd" instructions. This is the default except when compiling for CK803. --mmffppuu==_f_p_u Select the floating-point processor. This option can only be used with --mmhhaarrdd--ffllooaatt. Values for _f_p_u are ffppvv22__ssff (equivalent to --mmnnoo--ddoouubbllee--ffllooaatt --mmnnoo--ffddiivvdduu), ffppvv22 (--mmddoouubbllee--ffllooaatt --mmnnoo--ddiivvdduu), and ffppvv22__ddiivvdd (--mmddoouubbllee--ffllooaatt --mmddiivvdduu). --mmeellrrww --mmnnoo--eellrrww Enable the extended "lrw" instruction. This option defaults to on for CK801 and off otherwise. --mmiissttaacckk --mmnnoo--iissttaacckk Enable interrupt stack instructions; the default is off. The --mmiissttaacckk option is required to handle the "interrupt" and "isr" function attributes. --mmmmpp Enable multiprocessor instructions; the default is off. --mmccpp Enable coprocessor instructions; the default is off. --mmccaacchhee Enable coprocessor instructions; the default is off. --mmsseeccuurriittyy Enable C-SKY security instructions; the default is off. --mmttrruusstt Enable C-SKY trust instructions; the default is off. --mmddsspp --mmeeddsspp --mmvvddsspp Enable C-SKY DSP, Enhanced DSP, or Vector DSP instructions, respec- tively. All of these options default to off. --mmddiivv --mmnnoo--ddiivv Generate divide instructions. Default is off. --mmssmmaarrtt --mmnnoo--ssmmaarrtt Generate code for Smart Mode, using only registers numbered 0-7 to allow use of 16-bit instructions. This option is ignored for CK801 where this is the required behavior, and it defaults to on for CK802. For other targets, the default is off. --mmhhiigghh--rreeggiisstteerrss --mmnnoo--hhiigghh--rreeggiisstteerrss Generate code using the high registers numbered 16-31. This option is not supported on CK801, CK802, or CK803, and is enabled by de- fault for other processors. --mmaanncchhoorr --mmnnoo--aanncchhoorr Generate code using global anchor symbol addresses. --mmppuusshhppoopp --mmnnoo--ppuusshhppoopp Generate code using "push" and "pop" instructions. This option de- faults to on. --mmmmuullttiippllee--ssttlldd --mmssttmm --mmnnoo--mmuullttiippllee--ssttlldd --mmnnoo--ssttmm Generate code using "stm" and "ldm" instructions. This option isn't supported on CK801 but is enabled by default on other proces- sors. --mmccoonnssttppooooll --mmnnoo--ccoonnssttppooooll Create constant pools in the compiler instead of deferring it to the assembler. This option is the default and required for correct code generation on CK801 and CK802, and is optional on other pro- cessors. --mmssttaacckk--ssiizzee --mmnnoo--ssttaacckk--ssiizzee Emit ".stack_size" directives for each function in the assembly output. This option defaults to off. --mmccccrrtt --mmnnoo--ccccrrtt Generate code for the C-SKY compiler runtime instead of libgcc. This option defaults to off. --mmbbrraanncchh--ccoosstt==_n Set the branch costs to roughly "n" instructions. The default is 1. --mmsscchheedd--pprroolloogg --mmnnoo--sscchheedd--pprroolloogg Permit scheduling of function prologue and epilogue sequences. Us- ing this option can result in code that is not compliant with the C-SKY V2 ABI prologue requirements and that cannot be debugged or backtraced. It is disabled by default. --mmssiimm Links the library libsemi.a which is in compatible with simulator. Applicable to ELF compiler only. _D_a_r_w_i_n _O_p_t_i_o_n_s These options are defined for all architectures running the Darwin op- erating system. FSF GCC on Darwin does not create "fat" object files; it creates an ob- ject file for the single architecture that GCC was built to target. Apple's GCC on Darwin does create "fat" files if multiple --aarrcchh options are used; it does so by running the compiler or linker multiple times and joining the results together with _l_i_p_o. The subtype of the file created (like ppppcc77440000 or ppppcc997700 or ii668866) is de- termined by the flags that specify the ISA that GCC is targeting, like --mmccppuu or --mmaarrcchh. The --ffoorrccee__ccppuussuubbttyyppee__AALLLL option can be used to over- ride this. The Darwin tools vary in their behavior when presented with an ISA mis- match. The assembler, _a_s, only permits instructions to be used that are valid for the subtype of the file it is generating, so you cannot put 64-bit instructions in a ppppcc775500 object file. The linker for shared libraries, _/_u_s_r_/_b_i_n_/_l_i_b_t_o_o_l, fails and prints an error if asked to cre- ate a shared library with a less restrictive subtype than its input files (for instance, trying to put a ppppcc997700 object file in a ppppcc77440000 library). The linker for executables, lldd, quietly gives the executable the most restrictive subtype of any of its input files. --FF_d_i_r Add the framework directory _d_i_r to the head of the list of directo- ries to be searched for header files. These directories are inter- leaved with those specified by --II options and are scanned in a left-to-right order. A framework directory is a directory with frameworks in it. A framework is a directory with a _H_e_a_d_e_r_s and/or _P_r_i_v_a_t_e_H_e_a_d_e_r_s di- rectory contained directly in it that ends in _._f_r_a_m_e_w_o_r_k. The name of a framework is the name of this directory excluding the _._f_r_a_m_e_- _w_o_r_k. Headers associated with the framework are found in one of those two directories, with _H_e_a_d_e_r_s being searched first. A sub- framework is a framework directory that is in a framework's _F_r_a_m_e_- _w_o_r_k_s directory. Includes of subframework headers can only appear in a header of a framework that contains the subframework, or in a sibling subframework header. Two subframeworks are siblings if they occur in the same framework. A subframework should not have the same name as a framework; a warning is issued if this is vio- lated. Currently a subframework cannot have subframeworks; in the future, the mechanism may be extended to support this. The stan- dard frameworks can be found in _/_S_y_s_t_e_m_/_L_i_b_r_a_r_y_/_F_r_a_m_e_w_o_r_k_s and _/_L_i_- _b_r_a_r_y_/_F_r_a_m_e_w_o_r_k_s. An example include looks like "#include ", where _F_r_a_m_e_w_o_r_k denotes the name of the framework and _h_e_a_d_e_r_._h is found in the _P_r_i_v_a_t_e_H_e_a_d_e_r_s or _H_e_a_d_e_r_s directory. --iiffrraammeewwoorrkk_d_i_r Like --FF except the directory is a treated as a system directory. The main difference between this --iiffrraammeewwoorrkk and --FF is that with --iiffrraammeewwoorrkk the compiler does not warn about constructs contained within header files found via _d_i_r. This option is valid only for the C family of languages. --gguusseedd Emit debugging information for symbols that are used. For stabs debugging format, this enables --ffeelliimmiinnaattee--uunnuusseedd--ddeebbuugg--ssyymmbboollss. This is by default ON. --ggffuullll Emit debugging information for all symbols and types. --mmmmaaccoossxx--vveerrssiioonn--mmiinn==_v_e_r_s_i_o_n The earliest version of MacOS X that this executable will run on is _v_e_r_s_i_o_n. Typical values of _v_e_r_s_i_o_n include 10.1, 10.2, and 10.3.9. If the compiler was built to use the system's headers by default, then the default for this option is the system version on which the compiler is running, otherwise the default is to make choices that are compatible with as many systems and code bases as possible. --mmkkeerrnneell Enable kernel development mode. The --mmkkeerrnneell option sets --ssttaattiicc, --ffnnoo--ccoommmmoonn, --ffnnoo--uussee--ccxxaa--aatteexxiitt, --ffnnoo--eexxcceeppttiioonnss, --ffnnoo--nnoonn--ccaallll--eexxcceeppttiioonnss, --ffaappppllee--kkeexxtt, --ffnnoo--wweeaakk and --ffnnoo--rrttttii where applicable. This mode also sets --mmnnoo--aallttiivveecc, --mmssoofftt--ffllooaatt, --ffnnoo--bbuuiillttiinn and --mmlloonngg--bbrraanncchh for PowerPC targets. --mmoonnee--bbyyttee--bbooooll Override the defaults for "bool" so that "sizeof(bool)==1". By de- fault "sizeof(bool)" is 4 when compiling for Darwin/PowerPC and 1 when compiling for Darwin/x86, so this option has no effect on x86. WWaarrnniinngg:: The --mmoonnee--bbyyttee--bbooooll switch causes GCC to generate code that is not binary compatible with code generated without that switch. Using this switch may require recompiling all other mod- ules in a program, including system libraries. Use this switch to conform to a non-default data model. --mmffiixx--aanndd--ccoonnttiinnuuee --ffffiixx--aanndd--ccoonnttiinnuuee --ffiinnddiirreecctt--ddaattaa Generate code suitable for fast turnaround development, such as to allow GDB to dynamically load _._o files into already-running pro- grams. --ffiinnddiirreecctt--ddaattaa and --ffffiixx--aanndd--ccoonnttiinnuuee are provided for backwards compatibility. --aallll__llooaadd Loads all members of static archive libraries. See man _l_d(1) for more information. --aarrcchh__eerrrroorrss__ffaattaall Cause the errors having to do with files that have the wrong archi- tecture to be fatal. --bbiinndd__aatt__llooaadd Causes the output file to be marked such that the dynamic linker will bind all undefined references when the file is loaded or launched. --bbuunnddllee Produce a Mach-o bundle format file. See man _l_d(1) for more infor- mation. --bbuunnddllee__llooaaddeerr _e_x_e_c_u_t_a_b_l_e This option specifies the _e_x_e_c_u_t_a_b_l_e that will load the build out- put file being linked. See man _l_d(1) for more information. --ddyynnaammiicclliibb When passed this option, GCC produces a dynamic library instead of an executable when linking, using the Darwin _l_i_b_t_o_o_l command. --ffoorrccee__ccppuussuubbttyyppee__AALLLL This causes GCC's output file to have the AALLLL subtype, instead of one controlled by the --mmccppuu or --mmaarrcchh option. --aalllloowwaabbllee__cclliieenntt _c_l_i_e_n_t___n_a_m_e --cclliieenntt__nnaammee --ccoommppaattiibbiilliittyy__vveerrssiioonn --ccuurrrreenntt__vveerrssiioonn --ddeeaadd__ssttrriipp --ddeeppeennddeennccyy--ffiillee --ddyylliibb__ffiillee --ddyylliinnkkeerr__iinnssttaallll__nnaammee --ddyynnaammiicc --eexxppoorrtteedd__ssyymmbboollss__lliisstt --ffiilleelliisstt --ffllaatt__nnaammeessppaaccee --ffoorrccee__ffllaatt__nnaammeessppaaccee --hheeaaddeerrppaadd__mmaaxx__iinnssttaallll__nnaammeess --iimmaaggee__bbaassee --iinniitt --iinnssttaallll__nnaammee --kkeeeepp__pprriivvaattee__eexxtteerrnnss --mmuullttii__mmoodduullee --mmuullttiippllyy__ddeeffiinneedd --mmuullttiippllyy__ddeeffiinneedd__uunnuusseedd --nnooaallll__llooaadd --nnoo__ddeeaadd__ssttrriipp__iinniittss__aanndd__tteerrmmss --nnooffiixxpprreebbiinnddiinngg --nnoommuullttiiddeeffss --nnoopprreebbiinndd --nnoosseegglliinnkkeeddiitt --ppaaggeezzeerroo__ssiizzee --pprreebbiinndd --pprreebbiinndd__aallll__ttwwoolleevveell__mmoodduulleess --pprriivvaattee__bbuunnddllee --rreeaadd__oonnllyy__rreellooccss --sseeccttaalliiggnn --sseeccttoobbjjeeccttssyymmbboollss --wwhhyyllooaadd --sseegg11aaddddrr --sseeccttccrreeaattee --sseeccttoobbjjeeccttssyymmbboollss --sseeccttoorrddeerr --sseeggaaddddrr --sseeggss__rreeaadd__oonnllyy__aaddddrr --sseeggss__rreeaadd__wwrriittee__aaddddrr --sseegg__aaddddrr__ttaabbllee --sseegg__aaddddrr__ttaabbllee__ffiilleennaammee --sseegglliinnkkeeddiitt --sseeggpprroott --sseeggss__rreeaadd__oonnllyy__aaddddrr --sseeggss__rreeaadd__wwrriittee__aaddddrr --ssiinnggllee__mmoodduullee --ssttaattiicc --ssuubb__lliibbrraarryy --ssuubb__uummbbrreellllaa --ttwwoolleevveell__nnaammeessppaaccee --uummbbrreellllaa --uunnddeeffiinneedd --uunneexxppoorrtteedd__ssyymmbboollss__lliisstt --wweeaakk__rreeffeerreennccee__mmiissmmaattcchheess --wwhhaattssllooaaddeedd These options are passed to the Darwin linker. The Darwin linker man page describes them in detail. _D_E_C _A_l_p_h_a _O_p_t_i_o_n_s These --mm options are defined for the DEC Alpha implementations: --mmnnoo--ssoofftt--ffllooaatt --mmssoofftt--ffllooaatt Use (do not use) the hardware floating-point instructions for floating-point operations. When --mmssoofftt--ffllooaatt is specified, func- tions in _l_i_b_g_c_c_._a are used to perform floating-point operations. Unless they are replaced by routines that emulate the floating- point operations, or compiled in such a way as to call such emula- tions routines, these routines issue floating-point operations. If you are compiling for an Alpha without floating-point opera- tions, you must ensure that the library is built so as not to call them. Note that Alpha implementations without floating-point operations are required to have floating-point registers. --mmffpp--rreegg --mmnnoo--ffpp--rreeggss Generate code that uses (does not use) the floating-point register set. --mmnnoo--ffpp--rreeggss implies --mmssoofftt--ffllooaatt. If the floating-point register set is not used, floating-point operands are passed in in- teger registers as if they were integers and floating-point results are passed in $0 instead of $f0. This is a non-standard calling sequence, so any function with a floating-point argument or return value called by code compiled with --mmnnoo--ffpp--rreeggss must also be com- piled with that option. A typical use of this option is building a kernel that does not use, and hence need not save and restore, any floating-point regis- ters. --mmiieeeeee The Alpha architecture implements floating-point hardware optimized for maximum performance. It is mostly compliant with the IEEE floating-point standard. However, for full compliance, software assistance is required. This option generates code fully IEEE-com- pliant code _e_x_c_e_p_t that the _i_n_e_x_a_c_t_-_f_l_a_g is not maintained (see be- low). If this option is turned on, the preprocessor macro "_IEEE_FP" is defined during compilation. The resulting code is less efficient but is able to correctly support denormalized num- bers and exceptional IEEE values such as not-a-number and plus/mi- nus infinity. Other Alpha compilers call this option --iieeeeee__wwiitthh__nnoo__iinneexxaacctt. --mmiieeeeee--wwiitthh--iinneexxaacctt This is like --mmiieeeeee except the generated code also maintains the IEEE _i_n_e_x_a_c_t_-_f_l_a_g. Turning on this option causes the generated code to implement fully-compliant IEEE math. In addition to "_IEEE_FP", "_IEEE_FP_EXACT" is defined as a preprocessor macro. On some Alpha implementations the resulting code may execute sig- nificantly slower than the code generated by default. Since there is very little code that depends on the _i_n_e_x_a_c_t_-_f_l_a_g, you should normally not specify this option. Other Alpha compilers call this option --iieeeeee__wwiitthh__iinneexxaacctt. --mmffpp--ttrraapp--mmooddee==_t_r_a_p_-_m_o_d_e This option controls what floating-point related traps are enabled. Other Alpha compilers call this option --ffppttmm _t_r_a_p_-_m_o_d_e. The trap mode can be set to one of four values: nn This is the default (normal) setting. The only traps that are enabled are the ones that cannot be disabled in software (e.g., division by zero trap). uu In addition to the traps enabled by nn, underflow traps are en- abled as well. ssuu Like uu, but the instructions are marked to be safe for software completion (see Alpha architecture manual for details). ssuuii Like ssuu, but inexact traps are enabled as well. --mmffpp--rroouunnddiinngg--mmooddee==_r_o_u_n_d_i_n_g_-_m_o_d_e Selects the IEEE rounding mode. Other Alpha compilers call this option --ffpprrmm _r_o_u_n_d_i_n_g_-_m_o_d_e. The _r_o_u_n_d_i_n_g_-_m_o_d_e can be one of: nn Normal IEEE rounding mode. Floating-point numbers are rounded towards the nearest machine number or towards the even machine number in case of a tie. mm Round towards minus infinity. cc Chopped rounding mode. Floating-point numbers are rounded to- wards zero. dd Dynamic rounding mode. A field in the floating-point control register (_f_p_c_r, see Alpha architecture reference manual) con- trols the rounding mode in effect. The C library initializes this register for rounding towards plus infinity. Thus, unless your program modifies the _f_p_c_r, dd corresponds to round towards plus infinity. --mmttrraapp--pprreecciissiioonn==_t_r_a_p_-_p_r_e_c_i_s_i_o_n In the Alpha architecture, floating-point traps are imprecise. This means without software assistance it is impossible to recover from a floating trap and program execution normally needs to be terminated. GCC can generate code that can assist operating system trap handlers in determining the exact location that caused a floating-point trap. Depending on the requirements of an applica- tion, different levels of precisions can be selected: pp Program precision. This option is the default and means a trap handler can only identify which program caused a floating-point exception. ff Function precision. The trap handler can determine the func- tion that caused a floating-point exception. ii Instruction precision. The trap handler can determine the ex- act instruction that caused a floating-point exception. Other Alpha compilers provide the equivalent options called --ssccooppee__ssaaffee and --rreessuummppttiioonn__ssaaffee. --mmiieeeeee--ccoonnffoorrmmaanntt This option marks the generated code as IEEE conformant. You must not use this option unless you also specify --mmttrraapp--pprreecciissiioonn==ii and either --mmffpp--ttrraapp--mmooddee==ssuu or --mmffpp--ttrraapp--mmooddee==ssuuii. Its only effect is to emit the line ..eeffllaagg 4488 in the function prologue of the gener- ated assembly file. --mmbbuuiilldd--ccoonnssttaannttss Normally GCC examines a 32- or 64-bit integer constant to see if it can construct it from smaller constants in two or three instruc- tions. If it cannot, it outputs the constant as a literal and gen- erates code to load it from the data segment at run time. Use this option to require GCC to construct _a_l_l integer constants using code, even if it takes more instructions (the maximum is six). You typically use this option to build a shared library dynamic loader. Itself a shared library, it must relocate itself in memory before it can find the variables and constants in its own data seg- ment. --mmbbwwxx --mmnnoo--bbwwxx --mmcciixx --mmnnoo--cciixx --mmffiixx --mmnnoo--ffiixx --mmmmaaxx --mmnnoo--mmaaxx Indicate whether GCC should generate code to use the optional BWX, CIX, FIX and MAX instruction sets. The default is to use the in- struction sets supported by the CPU type specified via --mmccppuu== op- tion or that of the CPU on which GCC was built if none is speci- fied. --mmffllooaatt--vvaaxx --mmffllooaatt--iieeeeee Generate code that uses (does not use) VAX F and G floating-point arithmetic instead of IEEE single and double precision. --mmeexxpplliicciitt--rreellooccss --mmnnoo--eexxpplliicciitt--rreellooccss Older Alpha assemblers provided no way to generate symbol reloca- tions except via assembler macros. Use of these macros does not allow optimal instruction scheduling. GNU binutils as of version 2.12 supports a new syntax that allows the compiler to explicitly mark which relocations should apply to which instructions. This option is mostly useful for debugging, as GCC detects the capabili- ties of the assembler when it is built and sets the default accord- ingly. --mmssmmaallll--ddaattaa --mmllaarrggee--ddaattaa When --mmeexxpplliicciitt--rreellooccss is in effect, static data is accessed via _g_p_-_r_e_l_a_t_i_v_e relocations. When --mmssmmaallll--ddaattaa is used, objects 8 bytes long or smaller are placed in a _s_m_a_l_l _d_a_t_a _a_r_e_a (the ".sdata" and ".sbss" sections) and are accessed via 16-bit relocations off of the $gp register. This limits the size of the small data area to 64KB, but allows the variables to be directly accessed via a single instruction. The default is --mmllaarrggee--ddaattaa. With this option the data area is limited to just below 2GB. Programs that require more than 2GB of data must use "malloc" or "mmap" to allocate the data in the heap instead of in the program's data segment. When generating code for shared libraries, --ffppiicc implies --mmss-- mmaallll--ddaattaa and --ffPPIICC implies --mmllaarrggee--ddaattaa. --mmssmmaallll--tteexxtt --mmllaarrggee--tteexxtt When --mmssmmaallll--tteexxtt is used, the compiler assumes that the code of the entire program (or shared library) fits in 4MB, and is thus reachable with a branch instruction. When --mmssmmaallll--ddaattaa is used, the compiler can assume that all local symbols share the same $gp value, and thus reduce the number of instructions required for a function call from 4 to 1. The default is --mmllaarrggee--tteexxtt. --mmccppuu==_c_p_u___t_y_p_e Set the instruction set and instruction scheduling parameters for machine type _c_p_u___t_y_p_e. You can specify either the EEVV style name or the corresponding chip number. GCC supports scheduling parameters for the EV4, EV5 and EV6 family of processors and chooses the de- fault values for the instruction set from the processor you spec- ify. If you do not specify a processor type, GCC defaults to the processor on which the compiler was built. Supported values for _c_p_u___t_y_p_e are eevv44 eevv4455 2211006644 Schedules as an EV4 and has no instruction set extensions. eevv55 2211116644 Schedules as an EV5 and has no instruction set extensions. eevv5566 2211116644aa Schedules as an EV5 and supports the BWX extension. ppccaa5566 2211116644ppcc 2211116644PPCC Schedules as an EV5 and supports the BWX and MAX extensions. eevv66 2211226644 Schedules as an EV6 and supports the BWX, FIX, and MAX exten- sions. eevv6677 2211226644aa Schedules as an EV6 and supports the BWX, CIX, FIX, and MAX ex- tensions. Native toolchains also support the value nnaattiivvee, which selects the best architecture option for the host processor. --mmccppuu==nnaattiivvee has no effect if GCC does not recognize the processor. --mmttuunnee==_c_p_u___t_y_p_e Set only the instruction scheduling parameters for machine type _c_p_u___t_y_p_e. The instruction set is not changed. Native toolchains also support the value nnaattiivvee, which selects the best architecture option for the host processor. --mmttuunnee==nnaattiivvee has no effect if GCC does not recognize the processor. --mmmmeemmoorryy--llaatteennccyy==_t_i_m_e Sets the latency the scheduler should assume for typical memory references as seen by the application. This number is highly de- pendent on the memory access patterns used by the application and the size of the external cache on the machine. Valid options for _t_i_m_e are _n_u_m_b_e_r A decimal number representing clock cycles. LL11 LL22 LL33 mmaaiinn The compiler contains estimates of the number of clock cycles for "typical" EV4 & EV5 hardware for the Level 1, 2 & 3 caches (also called Dcache, Scache, and Bcache), as well as to main memory. Note that L3 is only valid for EV5. _e_B_P_F _O_p_t_i_o_n_s --mmffrraammee--lliimmiitt==_b_y_t_e_s This specifies the hard limit for frame sizes, in bytes. Cur- rently, the value that can be specified should be less than or equal to 3322776677. Defaults to whatever limit is imposed by the ver- sion of the Linux kernel targeted. --mmkkeerrnneell==_v_e_r_s_i_o_n This specifies the minimum version of the kernel that will run the compiled program. GCC uses this version to determine which in- structions to use, what kernel helpers to allow, etc. Currently, _v_e_r_s_i_o_n can be one of 44..00, 44..11, 44..22, 44..33, 44..44, 44..55, 44..66, 44..77, 44..88, 44..99, 44..1100, 44..1111, 44..1122, 44..1133, 44..1144, 44..1155, 44..1166, 44..1177, 44..1188, 44..1199, 44..2200, 55..00, 55..11, 55..22, llaatteesstt and nnaattiivvee. --mmbbiigg--eennddiiaann Generate code for a big-endian target. --mmlliittttllee--eennddiiaann Generate code for a little-endian target. This is the default. --mmjjmmppeexxtt Enable generation of extra conditional-branch instructions. En- abled for CPU v2 and above. --mmjjmmpp3322 Enable 32-bit jump instructions. Enabled for CPU v3 and above. --mmaalluu3322 Enable 32-bit ALU instructions. Enabled for CPU v3 and above. --mmccppuu==_v_e_r_s_i_o_n This specifies which version of the eBPF ISA to target. Newer ver- sions may not be supported by all kernels. The default is vv33. Supported values for _v_e_r_s_i_o_n are: vv11 The first stable eBPF ISA with no special features or exten- sions. vv22 Supports the jump extensions, as in --mmjjmmppeexxtt. vv33 All features of v2, plus: -<32-bit jump operations, as in --mmjjmmpp3322> -<32-bit ALU operations, as in --mmaalluu3322> --mmccoo--rree Enable BPF Compile Once - Run Everywhere (CO-RE) support. Requires and is implied by --ggbbttff. --mmnnoo--ccoo--rree Disable BPF Compile Once - Run Everywhere (CO-RE) support. BPF CO- RE support is enabled by default when generating BTF debug informa- tion for the BPF target. --mmxxbbppff Generate code for an expanded version of BPF, which relaxes some of the restrictions imposed by the BPF architecture: - exit, respectively. _F_R_3_0 _O_p_t_i_o_n_s These options are defined specifically for the FR30 port. --mmssmmaallll--mmooddeell Use the small address space model. This can produce smaller code, but it does assume that all symbolic values and addresses fit into a 20-bit range. --mmnnoo--llssiimm Assume that runtime support has been provided and so there is no need to include the simulator library (_l_i_b_s_i_m_._a) on the linker com- mand line. _F_T_3_2 _O_p_t_i_o_n_s These options are defined specifically for the FT32 port. --mmssiimm Specifies that the program will be run on the simulator. This causes an alternate runtime startup and library to be linked. You must not use this option when generating programs that will run on real hardware; you must provide your own runtime library for what- ever I/O functions are needed. --mmllrraa Enable Local Register Allocation. This is still experimental for FT32, so by default the compiler uses standard reload. --mmnnooddiivv Do not use div and mod instructions. --mmfftt3322bb Enable use of the extended instructions of the FT32B processor. --mmccoommpprreessss Compress all code using the Ft32B code compression scheme. --mmnnooppmm Do not generate code that reads program memory. _F_R_V _O_p_t_i_o_n_s --mmggpprr--3322 Only use the first 32 general-purpose registers. --mmggpprr--6644 Use all 64 general-purpose registers. --mmffpprr--3322 Use only the first 32 floating-point registers. --mmffpprr--6644 Use all 64 floating-point registers. --mmhhaarrdd--ffllooaatt Use hardware instructions for floating-point operations. --mmssoofftt--ffllooaatt Use library routines for floating-point operations. --mmaalllloocc--cccc Dynamically allocate condition code registers. --mmffiixxeedd--cccc Do not try to dynamically allocate condition code registers, only use "icc0" and "fcc0". --mmddwwoorrdd Change ABI to use double word insns. --mmnnoo--ddwwoorrdd Do not use double word instructions. --mmddoouubbllee Use floating-point double instructions. --mmnnoo--ddoouubbllee Do not use floating-point double instructions. --mmmmeeddiiaa Use media instructions. --mmnnoo--mmeeddiiaa Do not use media instructions. --mmmmuullaadddd Use multiply and add/subtract instructions. --mmnnoo--mmuullaadddd Do not use multiply and add/subtract instructions. --mmffddppiicc Select the FDPIC ABI, which uses function descriptors to represent pointers to functions. Without any PIC/PIE-related options, it im- plies --ffPPIIEE. With --ffppiicc or --ffppiiee, it assumes GOT entries and small data are within a 12-bit range from the GOT base address; with --ffPPIICC or --ffPPIIEE, GOT offsets are computed with 32 bits. With a bbffiinn--eellff target, this option implies --mmssiimm. --mmiinnlliinnee--pplltt Enable inlining of PLT entries in function calls to functions that are not known to bind locally. It has no effect without --mmffddppiicc. It's enabled by default if optimizing for speed and compiling for shared libraries (i.e., --ffPPIICC or --ffppiicc), or when an optimization option such as --OO33 or above is present in the command line. --mmTTLLSS Assume a large TLS segment when generating thread-local code. --mmttllss Do not assume a large TLS segment when generating thread-local code. --mmggpprreell--rroo Enable the use of "GPREL" relocations in the FDPIC ABI for data that is known to be in read-only sections. It's enabled by de- fault, except for --ffppiicc or --ffppiiee: even though it may help make the global offset table smaller, it trades 1 instruction for 4. With --ffPPIICC or --ffPPIIEE, it trades 3 instructions for 4, one of which may be shared by multiple symbols, and it avoids the need for a GOT entry for the referenced symbol, so it's more likely to be a win. If it is not, --mmnnoo--ggpprreell--rroo can be used to disable it. --mmuullttiilliibb--lliibbrraarryy--ppiicc Link with the (library, not FD) pic libraries. It's implied by --mmlliibbrraarryy--ppiicc, as well as by --ffPPIICC and --ffppiicc without --mmffddppiicc. You should never have to use it explicitly. --mmlliinnkkeedd--ffpp Follow the EABI requirement of always creating a frame pointer whenever a stack frame is allocated. This option is enabled by de- fault and can be disabled with --mmnnoo--lliinnkkeedd--ffpp. --mmlloonngg--ccaallllss Use indirect addressing to call functions outside the current com- pilation unit. This allows the functions to be placed anywhere within the 32-bit address space. --mmaalliiggnn--llaabbeellss Try to align labels to an 8-byte boundary by inserting NOPs into the previous packet. This option only has an effect when VLIW packing is enabled. It doesn't create new packets; it merely adds NOPs to existing ones. --mmlliibbrraarryy--ppiicc Generate position-independent EABI code. --mmaacccc--44 Use only the first four media accumulator registers. --mmaacccc--88 Use all eight media accumulator registers. --mmppaacckk Pack VLIW instructions. --mmnnoo--ppaacckk Do not pack VLIW instructions. --mmnnoo--eeffllaaggss Do not mark ABI switches in e_flags. --mmccoonndd--mmoovvee Enable the use of conditional-move instructions (default). This switch is mainly for debugging the compiler and will likely be removed in a future version. --mmnnoo--ccoonndd--mmoovvee Disable the use of conditional-move instructions. This switch is mainly for debugging the compiler and will likely be removed in a future version. --mmsscccc Enable the use of conditional set instructions (default). This switch is mainly for debugging the compiler and will likely be removed in a future version. --mmnnoo--sscccc Disable the use of conditional set instructions. This switch is mainly for debugging the compiler and will likely be removed in a future version. --mmccoonndd--eexxeecc Enable the use of conditional execution (default). This switch is mainly for debugging the compiler and will likely be removed in a future version. --mmnnoo--ccoonndd--eexxeecc Disable the use of conditional execution. This switch is mainly for debugging the compiler and will likely be removed in a future version. --mmvvlliiww--bbrraanncchh Run a pass to pack branches into VLIW instructions (default). This switch is mainly for debugging the compiler and will likely be removed in a future version. --mmnnoo--vvlliiww--bbrraanncchh Do not run a pass to pack branches into VLIW instructions. This switch is mainly for debugging the compiler and will likely be removed in a future version. --mmmmuullttii--ccoonndd--eexxeecc Enable optimization of "&&" and "||" in conditional execution (de- fault). This switch is mainly for debugging the compiler and will likely be removed in a future version. --mmnnoo--mmuullttii--ccoonndd--eexxeecc Disable optimization of "&&" and "||" in conditional execution. This switch is mainly for debugging the compiler and will likely be removed in a future version. --mmnneesstteedd--ccoonndd--eexxeecc Enable nested conditional execution optimizations (default). This switch is mainly for debugging the compiler and will likely be removed in a future version. --mmnnoo--nneesstteedd--ccoonndd--eexxeecc Disable nested conditional execution optimizations. This switch is mainly for debugging the compiler and will likely be removed in a future version. --mmooppttiimmiizzee--mmeemmbbaarr This switch removes redundant "membar" instructions from the com- piler-generated code. It is enabled by default. --mmnnoo--ooppttiimmiizzee--mmeemmbbaarr This switch disables the automatic removal of redundant "membar" instructions from the generated code. --mmttoommccaatt--ssttaattss Cause gas to print out tomcat statistics. --mmccppuu==_c_p_u Select the processor type for which to generate code. Possible values are ffrrvv, ffrr555500, ttoommccaatt, ffrr550000, ffrr445500, ffrr440055, ffrr440000, ffrr330000 and ssiimmppllee. _G_N_U_/_L_i_n_u_x _O_p_t_i_o_n_s These --mm options are defined for GNU/Linux targets: --mmgglliibbcc Use the GNU C library. This is the default except on **--**--lliinnuuxx--**uucclliibbcc**, **--**--lliinnuuxx--**mmuussll** and **--**--lliinnuuxx--**aannddrrooiidd** tar- gets. --mmuucclliibbcc Use uClibc C library. This is the default on **--**--lliinnuuxx--**uucclliibbcc** targets. --mmmmuussll Use the musl C library. This is the default on **--**--lliinnuuxx--**mmuussll** targets. --mmbbiioonniicc Use Bionic C library. This is the default on **--**--lliinnuuxx--**aannddrrooiidd** targets. --mmaannddrrooiidd Compile code compatible with Android platform. This is the default on **--**--lliinnuuxx--**aannddrrooiidd** targets. When compiling, this option enables --mmbbiioonniicc, --ffPPIICC, --ffnnoo--eexxcceepp-- ttiioonnss and --ffnnoo--rrttttii by default. When linking, this option makes the GCC driver pass Android-specific options to the linker. Fi- nally, this option causes the preprocessor macro "__ANDROID__" to be defined. --ttnnoo--aannddrrooiidd--cccc Disable compilation effects of --mmaannddrrooiidd, i.e., do not enable --mmbbiioonniicc, --ffPPIICC, --ffnnoo--eexxcceeppttiioonnss and --ffnnoo--rrttttii by default. --ttnnoo--aannddrrooiidd--lldd Disable linking effects of --mmaannddrrooiidd, i.e., pass standard Linux linking options to the linker. _H_8_/_3_0_0 _O_p_t_i_o_n_s These --mm options are defined for the H8/300 implementations: --mmrreellaaxx Shorten some address references at link time, when possible; uses the linker option --rreellaaxx. --mmhh Generate code for the H8/300H. --mmss Generate code for the H8S. --mmnn Generate code for the H8S and H8/300H in the normal mode. This switch must be used either with --mmhh or --mmss. --mmss22660000 Generate code for the H8S/2600. This switch must be used with --mmss. --mmeexxrr Extended registers are stored on stack before execution of function with monitor attribute. Default option is --mmeexxrr. This option is valid only for H8S targets. --mmnnoo--eexxrr Extended registers are not stored on stack before execution of function with monitor attribute. Default option is --mmnnoo--eexxrr. This option is valid only for H8S targets. --mmiinntt3322 Make "int" data 32 bits by default. --mmaalliiggnn--330000 On the H8/300H and H8S, use the same alignment rules as for the H8/300. The default for the H8/300H and H8S is to align longs and floats on 4-byte boundaries. --mmaalliiggnn--330000 causes them to be aligned on 2-byte boundaries. This option has no effect on the H8/300. _H_P_P_A _O_p_t_i_o_n_s These --mm options are defined for the HPPA family of computers: --mmaarrcchh==_a_r_c_h_i_t_e_c_t_u_r_e_-_t_y_p_e Generate code for the specified architecture. The choices for _a_r_- _c_h_i_t_e_c_t_u_r_e_-_t_y_p_e are 11..00 for PA 1.0, 11..11 for PA 1.1, and 22..00 for PA 2.0 processors. Refer to _/_u_s_r_/_l_i_b_/_s_c_h_e_d_._m_o_d_e_l_s on an HP-UX system to determine the proper architecture option for your machine. Code compiled for lower numbered architectures runs on higher numbered architectures, but not the other way around. --mmppaa--rriisscc--11--00 --mmppaa--rriisscc--11--11 --mmppaa--rriisscc--22--00 Synonyms for --mmaarrcchh==11..00, --mmaarrcchh==11..11, and --mmaarrcchh==22..00 respectively. --mmccaalllleerr--ccooppiieess The caller copies function arguments passed by hidden reference. This option should be used with care as it is not compatible with the default 32-bit runtime. However, only aggregates larger than eight bytes are passed by hidden reference and the option provides better compatibility with OpenMP. --mmjjuummpp--iinn--ddeellaayy This option is ignored and provided for compatibility purposes only. --mmddiissaabbllee--ffpprreeggss Prevent floating-point registers from being used in any manner. This is necessary for compiling kernels that perform lazy context switching of floating-point registers. If you use this option and attempt to perform floating-point operations, the compiler aborts. --mmddiissaabbllee--iinnddeexxiinngg Prevent the compiler from using indexing address modes. This avoids some rather obscure problems when compiling MIG generated code under MACH. --mmnnoo--ssppaaccee--rreeggss Generate code that assumes the target has no space registers. This allows GCC to generate faster indirect calls and use unscaled index address modes. Such code is suitable for level 0 PA systems and kernels. --mmffaasstt--iinnddiirreecctt--ccaallllss Generate code that assumes calls never cross space boundaries. This allows GCC to emit code that performs faster indirect calls. This option does not work in the presence of shared libraries or nested functions. --mmffiixxeedd--rraannggee==_r_e_g_i_s_t_e_r_-_r_a_n_g_e Generate code treating the given register range as fixed registers. A fixed register is one that the register allocator cannot use. This is useful when compiling kernel code. A register range is specified as two registers separated by a dash. Multiple register ranges can be specified separated by a comma. --mmlloonngg--llooaadd--ssttoorree Generate 3-instruction load and store sequences as sometimes re- quired by the HP-UX 10 linker. This is equivalent to the ++kk option to the HP compilers. --mmppoorrttaabbllee--rruunnttiimmee Use the portable calling conventions proposed by HP for ELF sys- tems. --mmggaass Enable the use of assembler directives only GAS understands. --mmsscchheedduullee==_c_p_u_-_t_y_p_e Schedule code according to the constraints for the machine type _c_p_u_-_t_y_p_e. The choices for _c_p_u_-_t_y_p_e are 770000 77110000, 77110000LLCC, 77220000, 77330000 and 88000000. Refer to _/_u_s_r_/_l_i_b_/_s_c_h_e_d_._m_o_d_e_l_s on an HP-UX system to determine the proper scheduling option for your machine. The default scheduling is 88000000. --mmlliinnkkeerr--oopptt Enable the optimization pass in the HP-UX linker. Note this makes symbolic debugging impossible. It also triggers a bug in the HP-UX 8 and HP-UX 9 linkers in which they give bogus error messages when linking some programs. --mmssoofftt--ffllooaatt Generate output containing library calls for floating point. WWaarrnn-- iinngg:: the requisite libraries are not available for all HPPA tar- gets. Normally the facilities of the machine's usual C compiler are used, but this cannot be done directly in cross-compilation. You must make your own arrangements to provide suitable library functions for cross-compilation. --mmssoofftt--ffllooaatt changes the calling convention in the output file; therefore, it is only useful if you compile _a_l_l of a program with this option. In particular, you need to compile _l_i_b_g_c_c_._a, the li- brary that comes with GCC, with --mmssoofftt--ffllooaatt in order for this to work. --mmssiioo Generate the predefine, "_SIO", for server IO. The default is --mmww-- ssiioo. This generates the predefines, "__hp9000s700", "__hp9000s700__" and "_WSIO", for workstation IO. These options are available under HP-UX and HI-UX. --mmggnnuu--lldd Use options specific to GNU lldd. This passes --sshhaarreedd to lldd when building a shared library. It is the default when GCC is config- ured, explicitly or implicitly, with the GNU linker. This option does not affect which lldd is called; it only changes what parameters are passed to that lldd. The lldd that is called is determined by the ----wwiitthh--lldd configure option, GCC's program search path, and finally by the user's PPAATTHH. The linker used by GCC can be printed using wwhhiicchh ``ggcccc --pprriinntt--pprroogg--nnaammee==lldd``. This option is only available on the 64-bit HP-UX GCC, i.e. configured with hhppppaa**6644**--**--hhppuuxx**. --mmhhpp--lldd Use options specific to HP lldd. This passes --bb to lldd when building a shared library and passes ++AAcccceepptt TTyyppeeMMiissmmaattcchh to lldd on all links. It is the default when GCC is configured, explicitly or im- plicitly, with the HP linker. This option does not affect which lldd is called; it only changes what parameters are passed to that lldd. The lldd that is called is determined by the ----wwiitthh--lldd configure op- tion, GCC's program search path, and finally by the user's PPAATTHH. The linker used by GCC can be printed using wwhhiicchh ``ggcccc --pprriinntt--pprroogg--nnaammee==lldd``. This option is only available on the 64-bit HP-UX GCC, i.e. configured with hhppppaa**6644**--**--hhppuuxx**. --mmlloonngg--ccaallllss Generate code that uses long call sequences. This ensures that a call is always able to reach linker generated stubs. The default is to generate long calls only when the distance from the call site to the beginning of the function or translation unit, as the case may be, exceeds a predefined limit set by the branch type being used. The limits for normal calls are 7,600,000 and 240,000 bytes, respectively for the PA 2.0 and PA 1.X architectures. Sibcalls are always limited at 240,000 bytes. Distances are measured from the beginning of functions when using the --ffffuunnccttiioonn--sseeccttiioonnss option, or when using the --mmggaass and --mmnnoo--ppoorrttaabbllee--rruunnttiimmee options together under HP-UX with the SOM linker. It is normally not desirable to use this option as it degrades per- formance. However, it may be useful in large applications, partic- ularly when partial linking is used to build the application. The types of long calls used depends on the capabilities of the as- sembler and linker, and the type of code being generated. The im- pact on systems that support long absolute calls, and long pic sym- bol-difference or pc-relative calls should be relatively small. However, an indirect call is used on 32-bit ELF systems in pic code and it is quite long. --mmuunniixx==_u_n_i_x_-_s_t_d Generate compiler predefines and select a startfile for the speci- fied UNIX standard. The choices for _u_n_i_x_-_s_t_d are 9933, 9955 and 9988. 9933 is supported on all HP-UX versions. 9955 is available on HP-UX 10.10 and later. 9988 is available on HP-UX 11.11 and later. The default values are 9933 for HP-UX 10.00, 9955 for HP-UX 10.10 though to 11.00, and 9988 for HP-UX 11.11 and later. --mmuunniixx==9933 provides the same predefines as GCC 3.3 and 3.4. --mmuu-- nniixx==9955 provides additional predefines for "XOPEN_UNIX" and "_XOPEN_SOURCE_EXTENDED", and the startfile _u_n_i_x_9_5_._o. --mmuunniixx==9988 provides additional predefines for "_XOPEN_UNIX", "_XOPEN_SOURCE_EXTENDED", "_INCLUDE__STDC_A1_SOURCE" and "_IN- CLUDE_XOPEN_SOURCE_500", and the startfile _u_n_i_x_9_8_._o. It is _i_m_p_o_r_t_a_n_t to note that this option changes the interfaces for various library routines. It also affects the operational behavior of the C library. Thus, _e_x_t_r_e_m_e care is needed in using this op- tion. Library code that is intended to operate with more than one UNIX standard must test, set and restore the variable "__xpg4_ex- tended_mask" as appropriate. Most GNU software doesn't provide this capability. --nnoolliibbddlldd Suppress the generation of link options to search libdld.sl when the --ssttaattiicc option is specified on HP-UX 10 and later. --ssttaattiicc The HP-UX implementation of setlocale in libc has a dependency on libdld.sl. There isn't an archive version of libdld.sl. Thus, when the --ssttaattiicc option is specified, special link options are needed to resolve this dependency. On HP-UX 10 and later, the GCC driver adds the necessary options to link with libdld.sl when the --ssttaattiicc option is specified. This causes the resulting binary to be dynamic. On the 64-bit port, the linkers generate dynamic binaries by default in any case. The --nnoo-- lliibbddlldd option can be used to prevent the GCC driver from adding these link options. --tthhrreeaaddss Add support for multithreading with the _d_c_e _t_h_r_e_a_d library under HP-UX. This option sets flags for both the preprocessor and linker. _I_A_-_6_4 _O_p_t_i_o_n_s These are the --mm options defined for the Intel IA-64 architecture. --mmbbiigg--eennddiiaann Generate code for a big-endian target. This is the default for HP-UX. --mmlliittttllee--eennddiiaann Generate code for a little-endian target. This is the default for AIX5 and GNU/Linux. --mmggnnuu--aass --mmnnoo--ggnnuu--aass Generate (or don't) code for the GNU assembler. This is the de- fault. --mmggnnuu--lldd --mmnnoo--ggnnuu--lldd Generate (or don't) code for the GNU linker. This is the default. --mmnnoo--ppiicc Generate code that does not use a global pointer register. The re- sult is not position independent code, and violates the IA-64 ABI. --mmvvoollaattiillee--aassmm--ssttoopp --mmnnoo--vvoollaattiillee--aassmm--ssttoopp Generate (or don't) a stop bit immediately before and after volatile asm statements. --mmrreeggiisstteerr--nnaammeess --mmnnoo--rreeggiisstteerr--nnaammeess Generate (or don't) iinn, lloocc, and oouutt register names for the stacked registers. This may make assembler output more readable. --mmnnoo--ssddaattaa --mmssddaattaa Disable (or enable) optimizations that use the small data section. This may be useful for working around optimizer bugs. --mmccoonnssttaanntt--ggpp Generate code that uses a single constant global pointer value. This is useful when compiling kernel code. --mmaauuttoo--ppiicc Generate code that is self-relocatable. This implies --mmccoonn-- ssttaanntt--ggpp. This is useful when compiling firmware code. --mmiinnlliinnee--ffllooaatt--ddiivviiddee--mmiinn--llaatteennccyy Generate code for inline divides of floating-point values using the minimum latency algorithm. --mmiinnlliinnee--ffllooaatt--ddiivviiddee--mmaaxx--tthhrroouugghhppuutt Generate code for inline divides of floating-point values using the maximum throughput algorithm. --mmnnoo--iinnlliinnee--ffllooaatt--ddiivviiddee Do not generate inline code for divides of floating-point values. --mmiinnlliinnee--iinntt--ddiivviiddee--mmiinn--llaatteennccyy Generate code for inline divides of integer values using the mini- mum latency algorithm. --mmiinnlliinnee--iinntt--ddiivviiddee--mmaaxx--tthhrroouugghhppuutt Generate code for inline divides of integer values using the maxi- mum throughput algorithm. --mmnnoo--iinnlliinnee--iinntt--ddiivviiddee Do not generate inline code for divides of integer values. --mmiinnlliinnee--ssqqrrtt--mmiinn--llaatteennccyy Generate code for inline square roots using the minimum latency al- gorithm. --mmiinnlliinnee--ssqqrrtt--mmaaxx--tthhrroouugghhppuutt Generate code for inline square roots using the maximum throughput algorithm. --mmnnoo--iinnlliinnee--ssqqrrtt Do not generate inline code for "sqrt". --mmffuusseedd--mmaadddd --mmnnoo--ffuusseedd--mmaadddd Do (don't) generate code that uses the fused multiply/add or multi- ply/subtract instructions. The default is to use these instruc- tions. --mmnnoo--ddwwaarrff22--aassmm --mmddwwaarrff22--aassmm Don't (or do) generate assembler code for the DWARF line number de- bugging info. This may be useful when not using the GNU assembler. --mmeeaarrllyy--ssttoopp--bbiittss --mmnnoo--eeaarrllyy--ssttoopp--bbiittss Allow stop bits to be placed earlier than immediately preceding the instruction that triggered the stop bit. This can improve instruc- tion scheduling, but does not always do so. --mmffiixxeedd--rraannggee==_r_e_g_i_s_t_e_r_-_r_a_n_g_e Generate code treating the given register range as fixed registers. A fixed register is one that the register allocator cannot use. This is useful when compiling kernel code. A register range is specified as two registers separated by a dash. Multiple register ranges can be specified separated by a comma. --mmttllss--ssiizzee==_t_l_s_-_s_i_z_e Specify bit size of immediate TLS offsets. Valid values are 14, 22, and 64. --mmttuunnee==_c_p_u_-_t_y_p_e Tune the instruction scheduling for a particular CPU, Valid values are iittaanniiuumm, iittaanniiuumm11, mmeerrcceedd, iittaanniiuumm22, and mmcckkiinnlleeyy. --mmiillpp3322 --mmllpp6644 Generate code for a 32-bit or 64-bit environment. The 32-bit envi- ronment sets int, long and pointer to 32 bits. The 64-bit environ- ment sets int to 32 bits and long and pointer to 64 bits. These are HP-UX specific flags. --mmnnoo--sscchheedd--bbrr--ddaattaa--ssppeecc --mmsscchheedd--bbrr--ddaattaa--ssppeecc (Dis/En)able data speculative scheduling before reload. This re- sults in generation of "ld.a" instructions and the corresponding check instructions ("ld.c" / "chk.a"). The default setting is dis- abled. --mmsscchheedd--aarr--ddaattaa--ssppeecc --mmnnoo--sscchheedd--aarr--ddaattaa--ssppeecc (En/Dis)able data speculative scheduling after reload. This re- sults in generation of "ld.a" instructions and the corresponding check instructions ("ld.c" / "chk.a"). The default setting is en- abled. --mmnnoo--sscchheedd--ccoonnttrrooll--ssppeecc --mmsscchheedd--ccoonnttrrooll--ssppeecc (Dis/En)able control speculative scheduling. This feature is available only during region scheduling (i.e. before reload). This results in generation of the "ld.s" instructions and the corre- sponding check instructions "chk.s". The default setting is dis- abled. --mmsscchheedd--bbrr--iinn--ddaattaa--ssppeecc --mmnnoo--sscchheedd--bbrr--iinn--ddaattaa--ssppeecc (En/Dis)able speculative scheduling of the instructions that are dependent on the data speculative loads before reload. This is ef- fective only with --mmsscchheedd--bbrr--ddaattaa--ssppeecc enabled. The default set- ting is enabled. --mmsscchheedd--aarr--iinn--ddaattaa--ssppeecc --mmnnoo--sscchheedd--aarr--iinn--ddaattaa--ssppeecc (En/Dis)able speculative scheduling of the instructions that are dependent on the data speculative loads after reload. This is ef- fective only with --mmsscchheedd--aarr--ddaattaa--ssppeecc enabled. The default set- ting is enabled. --mmsscchheedd--iinn--ccoonnttrrooll--ssppeecc --mmnnoo--sscchheedd--iinn--ccoonnttrrooll--ssppeecc (En/Dis)able speculative scheduling of the instructions that are dependent on the control speculative loads. This is effective only with --mmsscchheedd--ccoonnttrrooll--ssppeecc enabled. The default setting is enabled. --mmnnoo--sscchheedd--pprreeffeerr--nnoonn--ddaattaa--ssppeecc--iinnssnnss --mmsscchheedd--pprreeffeerr--nnoonn--ddaattaa--ssppeecc--iinnssnnss If enabled, data-speculative instructions are chosen for schedule only if there are no other choices at the moment. This makes the use of the data speculation much more conservative. The default setting is disabled. --mmnnoo--sscchheedd--pprreeffeerr--nnoonn--ccoonnttrrooll--ssppeecc--iinnssnnss --mmsscchheedd--pprreeffeerr--nnoonn--ccoonnttrrooll--ssppeecc--iinnssnnss If enabled, control-speculative instructions are chosen for sched- ule only if there are no other choices at the moment. This makes the use of the control speculation much more conservative. The de- fault setting is disabled. --mmnnoo--sscchheedd--ccoouunntt--ssppeecc--iinn--ccrriittiiccaall--ppaatthh --mmsscchheedd--ccoouunntt--ssppeecc--iinn--ccrriittiiccaall--ppaatthh If enabled, speculative dependencies are considered during computa- tion of the instructions priorities. This makes the use of the speculation a bit more conservative. The default setting is dis- abled. --mmsscchheedd--ssppeecc--llddcc Use a simple data speculation check. This option is on by default. --mmsscchheedd--ccoonnttrrooll--ssppeecc--llddcc Use a simple check for control speculation. This option is on by default. --mmsscchheedd--ssttoopp--bbiittss--aafftteerr--eevveerryy--ccyyccllee Place a stop bit after every cycle when scheduling. This option is on by default. --mmsscchheedd--ffpp--mmeemm--ddeeppss--zzeerroo--ccoosstt Assume that floating-point stores and loads are not likely to cause a conflict when placed into the same instruction group. This op- tion is disabled by default. --mmsseell--sscchheedd--ddoonntt--cchheecckk--ccoonnttrrooll--ssppeecc Generate checks for control speculation in selective scheduling. This flag is disabled by default. --mmsscchheedd--mmaaxx--mmeemmoorryy--iinnssnnss==_m_a_x_-_i_n_s_n_s Limit on the number of memory insns per instruction group, giving lower priority to subsequent memory insns attempting to schedule in the same instruction group. Frequently useful to prevent cache bank conflicts. The default value is 1. --mmsscchheedd--mmaaxx--mmeemmoorryy--iinnssnnss--hhaarrdd--lliimmiitt Makes the limit specified by mmsscchheedd--mmaaxx--mmeemmoorryy--iinnssnnss a hard limit, disallowing more than that number in an instruction group. Other- wise, the limit is "soft", meaning that non-memory operations are preferred when the limit is reached, but memory operations may still be scheduled. _L_M_3_2 _O_p_t_i_o_n_s These --mm options are defined for the LatticeMico32 architecture: --mmbbaarrrreell--sshhiifftt--eennaabblleedd Enable barrel-shift instructions. --mmddiivviiddee--eennaabblleedd Enable divide and modulus instructions. --mmmmuullttiippllyy--eennaabblleedd Enable multiply instructions. --mmssiiggnn--eexxtteenndd--eennaabblleedd Enable sign extend instructions. --mmuusseerr--eennaabblleedd Enable user-defined instructions. _L_o_o_n_g_A_r_c_h _O_p_t_i_o_n_s These command-line options are defined for LoongArch targets: --mmaarrcchh==_c_p_u_-_t_y_p_e Generate instructions for the machine type _c_p_u_-_t_y_p_e. In contrast to --mmttuunnee==_c_p_u_-_t_y_p_e, which merely tunes the generated code for the specified _c_p_u_-_t_y_p_e, --mmaarrcchh==_c_p_u_-_t_y_p_e allows GCC to generate code that may not run at all on processors other than the one indicated. Specifying --mmaarrcchh==_c_p_u_-_t_y_p_e implies --mmttuunnee==_c_p_u_-_t_y_p_e, except where noted otherwise. The choices for _c_p_u_-_t_y_p_e are: nnaattiivvee This selects the CPU to generate code for at compilation time by determining the processor type of the compiling machine. Using --mmaarrcchh==nnaattiivvee enables all instruction subsets supported by the local machine (hence the result might not run on differ- ent machines). Using --mmttuunnee==nnaattiivvee produces code optimized for the local machine under the constraints of the selected in- struction set. lloooonnggaarrcchh6644 A generic CPU with 64-bit extensions. llaa446644 LoongArch LA464 CPU with LBT, LSX, LASX, LVZ. --mmttuunnee==_c_p_u_-_t_y_p_e Optimize the output for the given processor, specified by microar- chitecture name. --mmaabbii==_b_a_s_e_-_a_b_i_-_t_y_p_e Generate code for the specified calling convention. _b_a_s_e_-_a_b_i_-_t_y_p_e can be one of: llpp6644dd Uses 64-bit general purpose registers and 32/64-bit floating- point registers for parameter passing. Data model is LP64, where iinntt is 32 bits, while lloonngg iinntt and pointers are 64 bits. llpp6644ff Uses 64-bit general purpose registers and 32-bit floating-point registers for parameter passing. Data model is LP64, where iinntt is 32 bits, while lloonngg iinntt and pointers are 64 bits. llpp6644ss Uses 64-bit general purpose registers and no floating-point registers for parameter passing. Data model is LP64, where iinntt is 32 bits, while lloonngg iinntt and pointers are 64 bits. --mmffppuu==_f_p_u_-_t_y_p_e Generate code for the specified FPU type, which can be one of: 6644 Allow the use of hardware floating-point instructions for 32-bit and 64-bit operations. 3322 Allow the use of hardware floating-point instructions for 32-bit operations. nnoonnee 00 Prevent the use of hardware floating-point instructions. --mmssoofftt--ffllooaatt Force --mmffppuu==nnoonnee and prevents the use of floating-point registers for parameter passing. This option may change the target ABI. --mmssiinnggllee--ffllooaatt Force --mmffppuu==3322 and allow the use of 32-bit floating-point registers for parameter passing. This option may change the target ABI. --mmddoouubbllee--ffllooaatt Force --mmffppuu==6644 and allow the use of 32/64-bit floating-point regis- ters for parameter passing. This option may change the target ABI. --mmbbrraanncchh--ccoosstt==_n Set the cost of branches to roughly _n instructions. --mmcchheecckk--zzeerroo--ddiivviissiioonn --mmnnoo--cchheecckk--zzeerroo--ddiivviissoonn Trap (do not trap) on integer division by zero. The default is --mmcchheecckk--zzeerroo--ddiivviissiioonn for --OO00 or --OOgg, and --mmnnoo--cchheecckk--zzeerroo--ddiivviissiioonn for other optimization levels. --mmccoonndd--mmoovvee--iinntt --mmnnoo--ccoonndd--mmoovvee--iinntt Conditional moves for integral data in general-purpose registers are enabled (disabled). The default is --mmccoonndd--mmoovvee--iinntt. --mmccoonndd--mmoovvee--ffllooaatt --mmnnoo--ccoonndd--mmoovvee--ffllooaatt Conditional moves for floating-point registers are enabled (dis- abled). The default is --mmccoonndd--mmoovvee--ffllooaatt. --mmmmeemmccppyy --mmnnoo--mmeemmccppyy Force (do not force) the use of "memcpy" for non-trivial block moves. The default is --mmnnoo--mmeemmccppyy, which allows GCC to inline most constant-sized copies. Setting optimization level to --OOss also forces the use of "memcpy", but --mmnnoo--mmeemmccppyy may override this be- havior if explicitly specified, regardless of the order these op- tions on the command line. --mmssttrriicctt--aalliiggnn --mmnnoo--ssttrriicctt--aalliiggnn Avoid or allow generating memory accesses that may not be aligned on a natural object boundary as described in the architecture spec- ification. The default is --mmnnoo--ssttrriicctt--aalliiggnn. --mmssmmaallll--ddaattaa--lliimmiitt==_n_u_m_b_e_r Put global and static data smaller than _n_u_m_b_e_r bytes into a special section (on some targets). The default value is 0. --mmmmaaxx--iinnlliinnee--mmeemmccppyy--ssiizzee==_n Inline all block moves (such as calls to "memcpy" or structure copies) less than or equal to _n bytes. The default value of _n is 1024. --mmccmmooddeell==_c_o_d_e_-_m_o_d_e_l Set the code model to one of: ttiinnyy--ssttaattiicc * local symbol and global strong symbol: The data section must be within +/-2MiB addressing space. The text section must be within +/-128MiB addressing space. * global weak symbol: The got table must be within +/-2GiB addressing space. ttiinnyy * local symbol: The data section must be within +/-2MiB ad- dressing space. The text section must be within +/-128MiB addressing space. * global symbol: The got table must be within +/-2GiB ad- dressing space. nnoorrmmaall * local symbol: The data section must be within +/-2GiB ad- dressing space. The text section must be within +/-128MiB addressing space. * global symbol: The got table must be within +/-2GiB ad- dressing space. llaarrggee * local symbol: The data section must be within +/-2GiB ad- dressing space. The text section must be within +/-128GiB addressing space. * global symbol: The got table must be within +/-2GiB ad- dressing space. eexxttrreemmee((NNoott iimmpplleemmeenntteedd yyeett)) * local symbol: The data and text section must be within +/-8EiB addressing space. * global symbol: The data got table must be within +/-8EiB addressing space. The default code model is "normal". _M_3_2_C _O_p_t_i_o_n_s --mmccppuu==_n_a_m_e Select the CPU for which code is generated. _n_a_m_e may be one of rr88cc for the R8C/Tiny series, mm1166cc for the M16C (up to /60) series, mm3322ccmm for the M16C/80 series, or mm3322cc for the M32C/80 series. --mmssiimm Specifies that the program will be run on the simulator. This causes an alternate runtime library to be linked in which supports, for example, file I/O. You must not use this option when generat- ing programs that will run on real hardware; you must provide your own runtime library for whatever I/O functions are needed. --mmeemmrreeggss==_n_u_m_b_e_r Specifies the number of memory-based pseudo-registers GCC uses dur- ing code generation. These pseudo-registers are used like real registers, so there is a tradeoff between GCC's ability to fit the code into available registers, and the performance penalty of using memory instead of registers. Note that all modules in a program must be compiled with the same value for this option. Because of that, you must not use this option with GCC's default runtime li- braries. _M_3_2_R_/_D _O_p_t_i_o_n_s These --mm options are defined for Renesas M32R/D architectures: --mm3322rr22 Generate code for the M32R/2. --mm3322rrxx Generate code for the M32R/X. --mm3322rr Generate code for the M32R. This is the default. --mmmmooddeell==ssmmaallll Assume all objects live in the lower 16MB of memory (so that their addresses can be loaded with the "ld24" instruction), and assume all subroutines are reachable with the "bl" instruction. This is the default. The addressability of a particular object can be set with the "model" attribute. --mmmmooddeell==mmeeddiiuumm Assume objects may be anywhere in the 32-bit address space (the compiler generates "seth/add3" instructions to load their ad- dresses), and assume all subroutines are reachable with the "bl" instruction. --mmmmooddeell==llaarrggee Assume objects may be anywhere in the 32-bit address space (the compiler generates "seth/add3" instructions to load their ad- dresses), and assume subroutines may not be reachable with the "bl" instruction (the compiler generates the much slower "seth/add3/jl" instruction sequence). --mmssddaattaa==nnoonnee Disable use of the small data area. Variables are put into one of ".data", ".bss", or ".rodata" (unless the "section" attribute has been specified). This is the default. The small data area consists of sections ".sdata" and ".sbss". Ob- jects may be explicitly put in the small data area with the "sec- tion" attribute using one of these sections. --mmssddaattaa==ssddaattaa Put small global and static data in the small data area, but do not generate special code to reference them. --mmssddaattaa==uussee Put small global and static data in the small data area, and gener- ate special instructions to reference them. --GG _n_u_m Put global and static objects less than or equal to _n_u_m bytes into the small data or BSS sections instead of the normal data or BSS sections. The default value of _n_u_m is 8. The --mmssddaattaa option must be set to one of ssddaattaa or uussee for this option to have any effect. All modules should be compiled with the same --GG _n_u_m value. Compil- ing with different values of _n_u_m may or may not work; if it doesn't the linker gives an error message---incorrect code is not gener- ated. --mmddeebbuugg Makes the M32R-specific code in the compiler display some statis- tics that might help in debugging programs. --mmaalliiggnn--llooooppss Align all loops to a 32-byte boundary. --mmnnoo--aalliiggnn--llooooppss Do not enforce a 32-byte alignment for loops. This is the default. --mmiissssuuee--rraattee==_n_u_m_b_e_r Issue _n_u_m_b_e_r instructions per cycle. _n_u_m_b_e_r can only be 1 or 2. --mmbbrraanncchh--ccoosstt==_n_u_m_b_e_r _n_u_m_b_e_r can only be 1 or 2. If it is 1 then branches are preferred over conditional code, if it is 2, then the opposite applies. --mmfflluusshh--ttrraapp==_n_u_m_b_e_r Specifies the trap number to use to flush the cache. The default is 12. Valid numbers are between 0 and 15 inclusive. --mmnnoo--fflluusshh--ttrraapp Specifies that the cache cannot be flushed by using a trap. --mmfflluusshh--ffuunncc==_n_a_m_e Specifies the name of the operating system function to call to flush the cache. The default is __fflluusshh__ccaacchhee, but a function call is only used if a trap is not available. --mmnnoo--fflluusshh--ffuunncc Indicates that there is no OS function for flushing the cache. _M_6_8_0_x_0 _O_p_t_i_o_n_s These are the --mm options defined for M680x0 and ColdFire processors. The default settings depend on which architecture was selected when the compiler was configured; the defaults for the most common choices are given below. --mmaarrcchh==_a_r_c_h Generate code for a specific M680x0 or ColdFire instruction set ar- chitecture. Permissible values of _a_r_c_h for M680x0 architectures are: 6688000000, 6688001100, 6688002200, 6688003300, 6688004400, 6688006600 and ccppuu3322. ColdFire architectures are selected according to Freescale's ISA classifica- tion and the permissible values are: iissaaaa, iissaaaapplluuss, iissaabb and iissaacc. GCC defines a macro "__mcf_a_r_c_h_____" whenever it is generating code for a ColdFire target. The _a_r_c_h in this macro is one of the --mmaarrcchh arguments given above. When used together, --mmaarrcchh and --mmttuunnee select code that runs on a family of similar processors but that is optimized for a particular microarchitecture. --mmccppuu==_c_p_u Generate code for a specific M680x0 or ColdFire processor. The M680x0 _c_p_us are: 6688000000, 6688001100, 6688002200, 6688003300, 6688004400, 6688006600, 6688330022, 6688333322 and ccppuu3322. The ColdFire _c_p_us are given by the table below, which also classifies the CPUs into families: _F_a_m_i_l_y : --mmccppuu _a_r_g_u_m_e_n_t_s 5511 : 5511 5511aacc 5511aagg 5511ccnn 5511eemm 5511jjee 5511jjff 5511jjgg 5511jjmm 5511mmmm 5511qqee 5511qqmm 55220066 : 55220022 55220044 55220066 55220066ee : 55220066ee 55220088 : 55220077 55220088 55221111aa : 55221100aa 55221111aa 55221133 : 55221111 55221122 55221133 55221166 : 55221144 55221166 5522223355 : 5522223300 5522223311 5522223322 5522223333 5522223344 5522223355 55222255 : 55222244 55222255 5522225599 : 5522225522 5522225544 5522225555 5522225566 5522225588 5522225599 55223355 : 55223322 55223333 55223344 55223355 552233xx 55224499 : 55224499 55225500 : 55225500 55227711 : 55227700 55227711 55227722 : 55227722 55227755 : 55227744 55227755 55228822 : 55228800 55228811 55228822 552288xx 5533001177 : 5533001111 5533001122 5533001133 5533001144 5533001155 5533001166 5533001177 55330077 : 55330077 55332299 : 55332277 55332288 55332299 553322xx 55337733 : 55337722 55337733 553377xx 55440077 : 55440077 55447755 : 55447700 55447711 55447722 55447733 55447744 55447755 554477xx 55448800 55448811 55448822 55448833 55448844 55448855 --mmccppuu==_c_p_u overrides --mmaarrcchh==_a_r_c_h if _a_r_c_h is compatible with _c_p_u. Other combinations of --mmccppuu and --mmaarrcchh are rejected. GCC defines the macro "__mcf_cpu__c_p_u_" when ColdFire target _c_p_u is selected. It also defines "__mcf_family__f_a_m_i_l_y_", where the value of _f_a_m_i_l_y is given by the table above. --mmttuunnee==_t_u_n_e Tune the code for a particular microarchitecture within the con- straints set by --mmaarrcchh and --mmccppuu. The M680x0 microarchitectures are: 6688000000, 6688001100, 6688002200, 6688003300, 6688004400, 6688006600 and ccppuu3322. The Cold- Fire microarchitectures are: ccffvv11, ccffvv22, ccffvv33, ccffvv44 and ccffvv44ee. You can also use --mmttuunnee==6688002200--4400 for code that needs to run rela- tively well on 68020, 68030 and 68040 targets. --mmttuunnee==6688002200--6600 is similar but includes 68060 targets as well. These two options se- lect the same tuning decisions as --mm6688002200--4400 and --mm6688002200--6600 respec- tively. GCC defines the macros "__mc_a_r_c_h_" and "__mc_a_r_c_h_____" when tuning for 680x0 architecture _a_r_c_h. It also defines "mc_a_r_c_h_" unless either --aannssii or a non-GNU --ssttdd option is used. If GCC is tuning for a range of architectures, as selected by --mmttuunnee==6688002200--4400 or --mmttuunnee==6688002200--6600, it defines the macros for every architecture in the range. GCC also defines the macro "__m_u_a_r_c_h_____" when tuning for ColdFire microarchitecture _u_a_r_c_h, where _u_a_r_c_h is one of the arguments given above. --mm6688000000 --mmcc6688000000 Generate output for a 68000. This is the default when the compiler is configured for 68000-based systems. It is equivalent to --mmaarrcchh==6688000000. Use this option for microcontrollers with a 68000 or EC000 core, including the 68008, 68302, 68306, 68307, 68322, 68328 and 68356. --mm6688001100 Generate output for a 68010. This is the default when the compiler is configured for 68010-based systems. It is equivalent to --mmaarrcchh==6688001100. --mm6688002200 --mmcc6688002200 Generate output for a 68020. This is the default when the compiler is configured for 68020-based systems. It is equivalent to --mmaarrcchh==6688002200. --mm6688003300 Generate output for a 68030. This is the default when the compiler is configured for 68030-based systems. It is equivalent to --mmaarrcchh==6688003300. --mm6688004400 Generate output for a 68040. This is the default when the compiler is configured for 68040-based systems. It is equivalent to --mmaarrcchh==6688004400. This option inhibits the use of 68881/68882 instructions that have to be emulated by software on the 68040. Use this option if your 68040 does not have code to emulate those instructions. --mm6688006600 Generate output for a 68060. This is the default when the compiler is configured for 68060-based systems. It is equivalent to --mmaarrcchh==6688006600. This option inhibits the use of 68020 and 68881/68882 instructions that have to be emulated by software on the 68060. Use this option if your 68060 does not have code to emulate those instructions. --mmccppuu3322 Generate output for a CPU32. This is the default when the compiler is configured for CPU32-based systems. It is equivalent to --mmaarrcchh==ccppuu3322. Use this option for microcontrollers with a CPU32 or CPU32+ core, including the 68330, 68331, 68332, 68333, 68334, 68336, 68340, 68341, 68349 and 68360. --mm55220000 Generate output for a 520X ColdFire CPU. This is the default when the compiler is configured for 520X-based systems. It is equiva- lent to --mmccppuu==55220066, and is now deprecated in favor of that option. Use this option for microcontroller with a 5200 core, including the MCF5202, MCF5203, MCF5204 and MCF5206. --mm55220066ee Generate output for a 5206e ColdFire CPU. The option is now depre- cated in favor of the equivalent --mmccppuu==55220066ee. --mm552288xx Generate output for a member of the ColdFire 528X family. The op- tion is now deprecated in favor of the equivalent --mmccppuu==552288xx. --mm55330077 Generate output for a ColdFire 5307 CPU. The option is now depre- cated in favor of the equivalent --mmccppuu==55330077. --mm55440077 Generate output for a ColdFire 5407 CPU. The option is now depre- cated in favor of the equivalent --mmccppuu==55440077. --mmccffvv44ee Generate output for a ColdFire V4e family CPU (e.g. 547x/548x). This includes use of hardware floating-point instructions. The op- tion is equivalent to --mmccppuu==554477xx, and is now deprecated in favor of that option. --mm6688002200--4400 Generate output for a 68040, without using any of the new instruc- tions. This results in code that can run relatively efficiently on either a 68020/68881 or a 68030 or a 68040. The generated code does use the 68881 instructions that are emulated on the 68040. The option is equivalent to --mmaarrcchh==6688002200 --mmttuunnee==6688002200--4400. --mm6688002200--6600 Generate output for a 68060, without using any of the new instruc- tions. This results in code that can run relatively efficiently on either a 68020/68881 or a 68030 or a 68040. The generated code does use the 68881 instructions that are emulated on the 68060. The option is equivalent to --mmaarrcchh==6688002200 --mmttuunnee==6688002200--6600. --mmhhaarrdd--ffllooaatt --mm6688888811 Generate floating-point instructions. This is the default for 68020 and above, and for ColdFire devices that have an FPU. It de- fines the macro "__HAVE_68881__" on M680x0 targets and "__mcffpu__" on ColdFire targets. --mmssoofftt--ffllooaatt Do not generate floating-point instructions; use library calls in- stead. This is the default for 68000, 68010, and 68832 targets. It is also the default for ColdFire devices that have no FPU. --mmddiivv --mmnnoo--ddiivv Generate (do not generate) ColdFire hardware divide and remainder instructions. If --mmaarrcchh is used without --mmccppuu, the default is "on" for ColdFire architectures and "off" for M680x0 architectures. Otherwise, the default is taken from the target CPU (either the de- fault CPU, or the one specified by --mmccppuu). For example, the de- fault is "off" for --mmccppuu==55220066 and "on" for --mmccppuu==55220066ee. GCC defines the macro "__mcfhwdiv__" when this option is enabled. --mmsshhoorrtt Consider type "int" to be 16 bits wide, like "short int". Addi- tionally, parameters passed on the stack are also aligned to a 16-bit boundary even on targets whose API mandates promotion to 32-bit. --mmnnoo--sshhoorrtt Do not consider type "int" to be 16 bits wide. This is the de- fault. --mmnnoobbiittffiieelldd --mmnnoo--bbiittffiieelldd Do not use the bit-field instructions. The --mm6688000000, --mmccppuu3322 and --mm55220000 options imply --mmnnoobbiittffiieelldd. --mmbbiittffiieelldd Do use the bit-field instructions. The --mm6688002200 option implies --mmbbiittffiieelldd. This is the default if you use a configuration de- signed for a 68020. --mmrrttdd Use a different function-calling convention, in which functions that take a fixed number of arguments return with the "rtd" in- struction, which pops their arguments while returning. This saves one instruction in the caller since there is no need to pop the ar- guments there. This calling convention is incompatible with the one normally used on Unix, so you cannot use it if you need to call libraries com- piled with the Unix compiler. Also, you must provide function prototypes for all functions that take variable numbers of arguments (including "printf"); otherwise incorrect code is generated for calls to those functions. In addition, seriously incorrect code results if you call a func- tion with too many arguments. (Normally, extra arguments are harm- lessly ignored.) The "rtd" instruction is supported by the 68010, 68020, 68030, 68040, 68060 and CPU32 processors, but not by the 68000 or 5200. The default is --mmnnoo--rrttdd. --mmaalliiggnn--iinntt --mmnnoo--aalliiggnn--iinntt Control whether GCC aligns "int", "long", "long long", "float", "double", and "long double" variables on a 32-bit boundary (--mmaa-- lliiggnn--iinntt) or a 16-bit boundary (--mmnnoo--aalliiggnn--iinntt). Aligning vari- ables on 32-bit boundaries produces code that runs somewhat faster on processors with 32-bit busses at the expense of more memory. WWaarrnniinngg:: if you use the --mmaalliiggnn--iinntt switch, GCC aligns structures containing the above types differently than most published applica- tion binary interface specifications for the m68k. Use the pc-relative addressing mode of the 68000 directly, instead of using a global offset table. At present, this option implies --ffppiicc, allowing at most a 16-bit offset for pc-relative addressing. --ffPPIICC is not presently supported with --mmppccrreell, though this could be supported for 68020 and higher processors. --mmnnoo--ssttrriicctt--aalliiggnn --mmssttrriicctt--aalliiggnn Do not (do) assume that unaligned memory references are handled by the system. --mmsseepp--ddaattaa Generate code that allows the data segment to be located in a dif- ferent area of memory from the text segment. This allows for exe- cute-in-place in an environment without virtual memory management. This option implies --ffPPIICC. --mmnnoo--sseepp--ddaattaa Generate code that assumes that the data segment follows the text segment. This is the default. --mmiidd--sshhaarreedd--lliibbrraarryy Generate code that supports shared libraries via the library ID method. This allows for execute-in-place and shared libraries in an environment without virtual memory management. This option im- plies --ffPPIICC. --mmnnoo--iidd--sshhaarreedd--lliibbrraarryy Generate code that doesn't assume ID-based shared libraries are be- ing used. This is the default. --mmsshhaarreedd--lliibbrraarryy--iidd==nn Specifies the identification number of the ID-based shared library being compiled. Specifying a value of 0 generates more compact code; specifying other values forces the allocation of that number to the current library, but is no more space- or time-efficient than omitting this option. --mmxxggoott --mmnnoo--xxggoott When generating position-independent code for ColdFire, generate code that works if the GOT has more than 8192 entries. This code is larger and slower than code generated without this option. On M680x0 processors, this option is not needed; --ffPPIICC suffices. GCC normally uses a single instruction to load values from the GOT. While this is relatively efficient, it only works if the GOT is smaller than about 64k. Anything larger causes the linker to re- port an error such as: relocation truncated to fit: R_68K_GOT16O foobar If this happens, you should recompile your code with --mmxxggoott. It should then work with very large GOTs. However, code generated with --mmxxggoott is less efficient, since it takes 4 instructions to fetch the value of a global symbol. Note that some linkers, including newer versions of the GNU linker, can create multiple GOTs and sort GOT entries. If you have such a linker, you should only need to use --mmxxggoott when compiling a single object file that accesses more than 8192 GOT entries. Very few do. These options have no effect unless GCC is generating position-in- dependent code. --mmlloonngg--jjuummpp--ttaabbllee--ooffffsseettss Use 32-bit offsets in "switch" tables. The default is to use 16-bit offsets. _M_C_o_r_e _O_p_t_i_o_n_s These are the --mm options defined for the Motorola M*Core processors. --mmhhaarrddlliitt --mmnnoo--hhaarrddlliitt Inline constants into the code stream if it can be done in two in- structions or less. --mmddiivv --mmnnoo--ddiivv Use the divide instruction. (Enabled by default). --mmrreellaaxx--iimmmmeeddiiaattee --mmnnoo--rreellaaxx--iimmmmeeddiiaattee Allow arbitrary-sized immediates in bit operations. --mmwwiiddee--bbiittffiieellddss --mmnnoo--wwiiddee--bbiittffiieellddss Always treat bit-fields as "int"-sized. --mm44bbyyttee--ffuunnccttiioonnss --mmnnoo--44bbyyttee--ffuunnccttiioonnss Force all functions to be aligned to a 4-byte boundary. --mmccaallllggrraapphh--ddaattaa --mmnnoo--ccaallllggrraapphh--ddaattaa Emit callgraph information. --mmssllooww--bbyytteess --mmnnoo--ssllooww--bbyytteess Prefer word access when reading byte quantities. --mmlliittttllee--eennddiiaann --mmbbiigg--eennddiiaann Generate code for a little-endian target. --mm221100 --mm334400 Generate code for the 210 processor. --mmnnoo--llssiimm Assume that runtime support has been provided and so omit the simu- lator library (_l_i_b_s_i_m_._a_) from the linker command line. --mmssttaacckk--iinnccrreemmeenntt==_s_i_z_e Set the maximum amount for a single stack increment operation. Large values can increase the speed of programs that contain func- tions that need a large amount of stack space, but they can also trigger a segmentation fault if the stack is extended too much. The default value is 0x1000. _M_e_P _O_p_t_i_o_n_s --mmaabbssddiiffff Enables the "abs" instruction, which is the absolute difference be- tween two registers. --mmaallll--ooppttss Enables all the optional instructions---average, multiply, divide, bit operations, leading zero, absolute difference, min/max, clip, and saturation. --mmaavveerraaggee Enables the "ave" instruction, which computes the average of two registers. --mmbbaasseedd==_n Variables of size _n bytes or smaller are placed in the ".based" section by default. Based variables use the $tp register as a base register, and there is a 128-byte limit to the ".based" section. --mmbbiittooppss Enables the bit operation instructions---bit test ("btstm"), set ("bsetm"), clear ("bclrm"), invert ("bnotm"), and test-and-set ("tas"). --mmcc==_n_a_m_e Selects which section constant data is placed in. _n_a_m_e may be ttiinnyy, nneeaarr, or ffaarr. --mmcclliipp Enables the "clip" instruction. Note that --mmcclliipp is not useful un- less you also provide --mmmmiinnmmaaxx. --mmccoonnffiigg==_n_a_m_e Selects one of the built-in core configurations. Each MeP chip has one or more modules in it; each module has a core CPU and a variety of coprocessors, optional instructions, and peripherals. The "MeP-Integrator" tool, not part of GCC, provides these configura- tions through this option; using this option is the same as using all the corresponding command-line options. The default configura- tion is ddeeffaauulltt. --mmccoopp Enables the coprocessor instructions. By default, this is a 32-bit coprocessor. Note that the coprocessor is normally enabled via the --mmccoonnffiigg== option. --mmccoopp3322 Enables the 32-bit coprocessor's instructions. --mmccoopp6644 Enables the 64-bit coprocessor's instructions. --mmiivvcc22 Enables IVC2 scheduling. IVC2 is a 64-bit VLIW coprocessor. --mmddcc Causes constant variables to be placed in the ".near" section. --mmddiivv Enables the "div" and "divu" instructions. --mmeebb Generate big-endian code. --mmeell Generate little-endian code. --mmiioo--vvoollaattiillee Tells the compiler that any variable marked with the "io" attribute is to be considered volatile. --mmll Causes variables to be assigned to the ".far" section by default. --mmlleeaaddzz Enables the "leadz" (leading zero) instruction. --mmmm Causes variables to be assigned to the ".near" section by default. --mmmmiinnmmaaxx Enables the "min" and "max" instructions. --mmmmuulltt Enables the multiplication and multiply-accumulate instructions. --mmnnoo--ooppttss Disables all the optional instructions enabled by --mmaallll--ooppttss. --mmrreeppeeaatt Enables the "repeat" and "erepeat" instructions, used for low-over- head looping. --mmss Causes all variables to default to the ".tiny" section. Note that there is a 65536-byte limit to this section. Accesses to these variables use the %gp base register. --mmssaattuurr Enables the saturation instructions. Note that the compiler does not currently generate these itself, but this option is included for compatibility with other tools, like "as". --mmssddrraamm Link the SDRAM-based runtime instead of the default ROM-based run- time. --mmssiimm Link the simulator run-time libraries. --mmssiimmnnoovveecc Link the simulator runtime libraries, excluding built-in support for reset and exception vectors and tables. --mmttff Causes all functions to default to the ".far" section. Without this option, functions default to the ".near" section. --mmttiinnyy==_n Variables that are _n bytes or smaller are allocated to the ".tiny" section. These variables use the $gp base register. The default for this option is 4, but note that there's a 65536-byte limit to the ".tiny" section. _M_i_c_r_o_B_l_a_z_e _O_p_t_i_o_n_s --mmssoofftt--ffllooaatt Use software emulation for floating point (default). --mmhhaarrdd--ffllooaatt Use hardware floating-point instructions. --mmmmeemmccppyy Do not optimize block moves, use "memcpy". --mmnnoo--cclleeaarrbbssss This option is deprecated. Use --ffnnoo--zzeerroo--iinniittiiaalliizzeedd--iinn--bbssss in- stead. --mmccppuu==_c_p_u_-_t_y_p_e Use features of, and schedule code for, the given CPU. Supported values are in the format vv_X.._Y_Y.._Z, where _X is a major version, _Y_Y is the minor version, and _Z is compatibility code. Example values are vv33..0000..aa, vv44..0000..bb, vv55..0000..aa, vv55..0000..bb, vv66..0000..aa. --mmxxll--ssoofftt--mmuull Use software multiply emulation (default). --mmxxll--ssoofftt--ddiivv Use software emulation for divides (default). --mmxxll--bbaarrrreell--sshhiifftt Use the hardware barrel shifter. --mmxxll--ppaatttteerrnn--ccoommppaarree Use pattern compare instructions. --mmssmmaallll--ddiivviiddeess Use table lookup optimization for small signed integer divisions. --mmxxll--ssttaacckk--cchheecckk This option is deprecated. Use --ffssttaacckk--cchheecckk instead. --mmxxll--ggpp--oopptt Use GP-relative ".sdata"/".sbss" sections. --mmxxll--mmuullttiippllyy--hhiigghh Use multiply high instructions for high part of 32x32 multiply. --mmxxll--ffllooaatt--ccoonnvveerrtt Use hardware floating-point conversion instructions. --mmxxll--ffllooaatt--ssqqrrtt Use hardware floating-point square root instruction. --mmbbiigg--eennddiiaann Generate code for a big-endian target. --mmlliittttllee--eennddiiaann Generate code for a little-endian target. --mmxxll--rreeoorrddeerr Use reorder instructions (swap and byte reversed load/store). --mmxxll--mmooddee--_a_p_p_-_m_o_d_e_l Select application model _a_p_p_-_m_o_d_e_l. Valid models are eexxeeccuuttaabbllee normal executable (default), uses startup code _c_r_t_0_._o. xxmmddssttuubb for use with Xilinx Microprocessor Debugger (XMD) based soft- ware intrusive debug agent called xmdstub. This uses startup file _c_r_t_1_._o and sets the start address of the program to 0x800. bboooottssttrraapp for applications that are loaded using a bootloader. This model uses startup file _c_r_t_2_._o which does not contain a proces- sor reset vector handler. This is suitable for transferring control on a processor reset to the bootloader rather than the application. nnoovveeccttoorrss for applications that do not require any of the MicroBlaze vec- tors. This option may be useful for applications running within a monitoring application. This model uses _c_r_t_3_._o as a startup file. Option --xxll--mmooddee--_a_p_p_-_m_o_d_e_l is a deprecated alias for --mmxxll--mmooddee--_a_p_p_- _m_o_d_e_l. --mmppiicc--ddaattaa--iiss--tteexxtt--rreellaattiivvee Assume that the displacement between the text and data segments is fixed at static link time. This allows data to be referenced by offset from start of text address instead of GOT since PC-relative addressing is not supported. _M_I_P_S _O_p_t_i_o_n_s --EEBB Generate big-endian code. --EELL Generate little-endian code. This is the default for mmiippss**eell--**--** configurations. --mmaarrcchh==_a_r_c_h Generate code that runs on _a_r_c_h, which can be the name of a generic MIPS ISA, or the name of a particular processor. The ISA names are: mmiippss11, mmiippss22, mmiippss33, mmiippss44, mmiippss3322, mmiippss3322rr22, mmiippss3322rr33, mmiippss3322rr55, mmiippss3322rr66, mmiippss6644, mmiippss6644rr22, mmiippss6644rr33, mmiippss6644rr55 and mmiippss6644rr66. The processor names are: 44kkcc, 44kkmm, 44kkpp, 44kksscc, 44kkeecc, 44kkeemm, 44kkeepp, 44kkssdd, 55kkcc, 55kkff, 2200kkcc, 2244kkcc, 2244kkff22__11, 2244kkff11__11, 2244kkeecc, 2244kkeeff22__11, 2244kkeeff11__11, 3344kkcc, 3344kkff22__11, 3344kkff11__11, 3344kknn, 7744kkcc, 7744kkff22__11, 7744kkff11__11, 7744kkff33__22, 11000044kkcc, 11000044kkff22__11, 11000044kkff11__11, ii66440000, ii66550000, iinn-- tteerraappttiivv, lloooonnggssoonn22ee, lloooonnggssoonn22ff, lloooonnggssoonn33aa, ggss446644, ggss446644ee, ggss226644ee, mm44kk, mm1144kk, mm1144kkcc, mm1144kkee, mm1144kkeecc, mm55110000, mm55110011, oocctteeoonn, oocctteeoonn++, oocctteeoonn22, oocctteeoonn33, oorriioonn, pp55660000, pp66660000, rr22000000, rr33000000, rr33990000, rr44000000, rr44440000, rr44660000, rr44665500, rr44770000, rr55990000, rr66000000, rr88000000, rrmm77000000, rrmm99000000, rr1100000000, rr1122000000, rr1144000000, rr1166000000, ssbb11, ssrr7711000000, vvrr44110000, vvrr44111111, vvrr44112200, vvrr44113300, vvrr44330000, vvrr55000000, vvrr55440000, vvrr55550000, xxllrr and xxllpp. The special value ffrroomm--aabbii selects the most compatible architecture for the selected ABI (that is, mmiippss11 for 32-bit ABIs and mmiippss33 for 64-bit ABIs). The native Linux/GNU toolchain also supports the value nnaattiivvee, which selects the best architecture option for the host processor. --mmaarrcchh==nnaattiivvee has no effect if GCC does not recognize the proces- sor. In processor names, a final 000000 can be abbreviated as kk (for exam- ple, --mmaarrcchh==rr22kk). Prefixes are optional, and vvrr may be written rr. Names of the form _nff22__11 refer to processors with FPUs clocked at half the rate of the core, names of the form _nff11__11 refer to proces- sors with FPUs clocked at the same rate as the core, and names of the form _nff33__22 refer to processors with FPUs clocked a ratio of 3:2 with respect to the core. For compatibility reasons, _nff is ac- cepted as a synonym for _nff22__11 while _nxx and _bffxx are accepted as syn- onyms for _nff11__11. GCC defines two macros based on the value of this option. The first is "_MIPS_ARCH", which gives the name of target architecture, as a string. The second has the form "_MIPS_ARCH__f_o_o_", where _f_o_o is the capitalized value of "_MIPS_ARCH". For example, --mmaarrcchh==rr22000000 sets "_MIPS_ARCH" to "r2000" and defines the macro "_MIPS_ARCH_R2000". Note that the "_MIPS_ARCH" macro uses the processor names given above. In other words, it has the full prefix and does not abbre- viate 000000 as kk. In the case of ffrroomm--aabbii, the macro names the re- solved architecture (either "mips1" or "mips3"). It names the de- fault architecture when no --mmaarrcchh option is given. --mmttuunnee==_a_r_c_h Optimize for _a_r_c_h. Among other things, this option controls the way instructions are scheduled, and the perceived cost of arith- metic operations. The list of _a_r_c_h values is the same as for --mmaarrcchh. When this option is not used, GCC optimizes for the processor spec- ified by --mmaarrcchh. By using --mmaarrcchh and --mmttuunnee together, it is possi- ble to generate code that runs on a family of processors, but opti- mize the code for one particular member of that family. --mmttuunnee defines the macros "_MIPS_TUNE" and "_MIPS_TUNE__f_o_o_", which work in the same way as the --mmaarrcchh ones described above. --mmiippss11 Equivalent to --mmaarrcchh==mmiippss11. --mmiippss22 Equivalent to --mmaarrcchh==mmiippss22. --mmiippss33 Equivalent to --mmaarrcchh==mmiippss33. --mmiippss44 Equivalent to --mmaarrcchh==mmiippss44. --mmiippss3322 Equivalent to --mmaarrcchh==mmiippss3322. --mmiippss3322rr33 Equivalent to --mmaarrcchh==mmiippss3322rr33. --mmiippss3322rr55 Equivalent to --mmaarrcchh==mmiippss3322rr55. --mmiippss3322rr66 Equivalent to --mmaarrcchh==mmiippss3322rr66. --mmiippss6644 Equivalent to --mmaarrcchh==mmiippss6644. --mmiippss6644rr22 Equivalent to --mmaarrcchh==mmiippss6644rr22. --mmiippss6644rr33 Equivalent to --mmaarrcchh==mmiippss6644rr33. --mmiippss6644rr55 Equivalent to --mmaarrcchh==mmiippss6644rr55. --mmiippss6644rr66 Equivalent to --mmaarrcchh==mmiippss6644rr66. --mmiippss1166 --mmnnoo--mmiippss1166 Generate (do not generate) MIPS16 code. If GCC is targeting a MIPS32 or MIPS64 architecture, it makes use of the MIPS16e ASE. MIPS16 code generation can also be controlled on a per-function ba- sis by means of "mips16" and "nomips16" attributes. --mmfflliipp--mmiippss1166 Generate MIPS16 code on alternating functions. This option is pro- vided for regression testing of mixed MIPS16/non-MIPS16 code gener- ation, and is not intended for ordinary use in compiling user code. --mmiinntteerrlliinnkk--ccoommpprreesssseedd --mmnnoo--iinntteerrlliinnkk--ccoommpprreesssseedd Require (do not require) that code using the standard (uncom- pressed) MIPS ISA be link-compatible with MIPS16 and microMIPS code, and vice versa. For example, code using the standard ISA encoding cannot jump di- rectly to MIPS16 or microMIPS code; it must either use a call or an indirect jump. --mmiinntteerrlliinnkk--ccoommpprreesssseedd therefore disables direct jumps unless GCC knows that the target of the jump is not com- pressed. --mmiinntteerrlliinnkk--mmiippss1166 --mmnnoo--iinntteerrlliinnkk--mmiippss1166 Aliases of --mmiinntteerrlliinnkk--ccoommpprreesssseedd and --mmnnoo--iinntteerrlliinnkk--ccoommpprreesssseedd. These options predate the microMIPS ASE and are retained for back- wards compatibility. --mmaabbii==3322 --mmaabbii==oo6644 --mmaabbii==nn3322 --mmaabbii==6644 --mmaabbii==eeaabbii Generate code for the given ABI. Note that the EABI has a 32-bit and a 64-bit variant. GCC normally generates 64-bit code when you select a 64-bit architecture, but you can use --mmggpp3322 to get 32-bit code instead. For information about the O64 ABI, see . GCC supports a variant of the o32 ABI in which floating-point reg- isters are 64 rather than 32 bits wide. You can select this combi- nation with --mmaabbii==3322 --mmffpp6644. This ABI relies on the "mthc1" and "mfhc1" instructions and is therefore only supported for MIPS32R2, MIPS32R3 and MIPS32R5 processors. The register assignments for arguments and return values remain the same, but each scalar value is passed in a single 64-bit register rather than a pair of 32-bit registers. For example, scalar float- ing-point values are returned in $$ff00 only, not a $$ff00/$$ff11 pair. The set of call-saved registers also remains the same in that the even- numbered double-precision registers are saved. Two additional variants of the o32 ABI are supported to enable a transition from 32-bit to 64-bit registers. These are FPXX (--mmff-- ppxxxx) and FP64A (--mmffpp6644 --mmnnoo--oodddd--sspprreegg). The FPXX extension man- dates that all code must execute correctly when run using 32-bit or 64-bit registers. The code can be interlinked with either FP32 or FP64, but not both. The FP64A extension is similar to the FP64 ex- tension but forbids the use of odd-numbered single-precision regis- ters. This can be used in conjunction with the "FRE" mode of FPUs in MIPS32R5 processors and allows both FP32 and FP64A code to in- terlink and run in the same process without changing FPU modes. --mmaabbiiccaallllss --mmnnoo--aabbiiccaallllss Generate (do not generate) code that is suitable for SVR4-style dy- namic objects. --mmaabbiiccaallllss is the default for SVR4-based systems. --mmsshhaarreedd --mmnnoo--sshhaarreedd Generate (do not generate) code that is fully position-independent, and that can therefore be linked into shared libraries. This op- tion only affects --mmaabbiiccaallllss. All --mmaabbiiccaallllss code has traditionally been position-independent, regardless of options like --ffPPIICC and --ffppiicc. However, as an exten- sion, the GNU toolchain allows executables to use absolute accesses for locally-binding symbols. It can also use shorter GP initial- ization sequences and generate direct calls to locally-defined functions. This mode is selected by --mmnnoo--sshhaarreedd. --mmnnoo--sshhaarreedd depends on binutils 2.16 or higher and generates ob- jects that can only be linked by the GNU linker. However, the op- tion does not affect the ABI of the final executable; it only af- fects the ABI of relocatable objects. Using --mmnnoo--sshhaarreedd generally makes executables both smaller and quicker. --mmsshhaarreedd is the default. --mmpplltt --mmnnoo--pplltt Assume (do not assume) that the static and dynamic linkers support PLTs and copy relocations. This option only affects --mmnnoo--sshhaarreedd --mmaabbiiccaallllss. For the n64 ABI, this option has no effect without --mmssyymm3322. You can make --mmpplltt the default by configuring GCC with ----wwiitthh--mmiippss--pplltt. The default is --mmnnoo--pplltt otherwise. --mmxxggoott --mmnnoo--xxggoott Lift (do not lift) the usual restrictions on the size of the global offset table. GCC normally uses a single instruction to load values from the GOT. While this is relatively efficient, it only works if the GOT is smaller than about 64k. Anything larger causes the linker to re- port an error such as: relocation truncated to fit: R_MIPS_GOT16 foobar If this happens, you should recompile your code with --mmxxggoott. This works with very large GOTs, although the code is also less effi- cient, since it takes three instructions to fetch the value of a global symbol. Note that some linkers can create multiple GOTs. If you have such a linker, you should only need to use --mmxxggoott when a single object file accesses more than 64k's worth of GOT entries. Very few do. These options have no effect unless GCC is generating position in- dependent code. --mmggpp3322 Assume that general-purpose registers are 32 bits wide. --mmggpp6644 Assume that general-purpose registers are 64 bits wide. --mmffpp3322 Assume that floating-point registers are 32 bits wide. --mmffpp6644 Assume that floating-point registers are 64 bits wide. --mmffppxxxx Do not assume the width of floating-point registers. --mmhhaarrdd--ffllooaatt Use floating-point coprocessor instructions. --mmssoofftt--ffllooaatt Do not use floating-point coprocessor instructions. Implement floating-point calculations using library calls instead. --mmnnoo--ffllooaatt Equivalent to --mmssoofftt--ffllooaatt, but additionally asserts that the pro- gram being compiled does not perform any floating-point operations. This option is presently supported only by some bare-metal MIPS configurations, where it may select a special set of libraries that lack all floating-point support (including, for example, the float- ing-point "printf" formats). If code compiled with --mmnnoo--ffllooaatt ac- cidentally contains floating-point operations, it is likely to suf- fer a link-time or run-time failure. --mmssiinnggllee--ffllooaatt Assume that the floating-point coprocessor only supports single- precision operations. --mmddoouubbllee--ffllooaatt Assume that the floating-point coprocessor supports double-preci- sion operations. This is the default. --mmoodddd--sspprreegg --mmnnoo--oodddd--sspprreegg Enable the use of odd-numbered single-precision floating-point reg- isters for the o32 ABI. This is the default for processors that are known to support these registers. When using the o32 FPXX ABI, --mmnnoo--oodddd--sspprreegg is set by default. --mmaabbss==22000088 --mmaabbss==lleeggaaccyy These options control the treatment of the special not-a-number (NaN) IEEE 754 floating-point data with the "abs._f_m_t_" and "neg._f_m_t_" machine instructions. By default or when --mmaabbss==lleeggaaccyy is used the legacy treatment is se- lected. In this case these instructions are considered arithmetic and avoided where correct operation is required and the input oper- and might be a NaN. A longer sequence of instructions that manipu- late the sign bit of floating-point datum manually is used instead unless the --ffffiinniittee--mmaatthh--oonnllyy option has also been specified. The --mmaabbss==22000088 option selects the IEEE 754-2008 treatment. In this case these instructions are considered non-arithmetic and therefore operating correctly in all cases, including in particular where the input operand is a NaN. These instructions are therefore always used for the respective operations. --mmnnaann==22000088 --mmnnaann==lleeggaaccyy These options control the encoding of the special not-a-number (NaN) IEEE 754 floating-point data. The --mmnnaann==lleeggaaccyy option selects the legacy encoding. In this case quiet NaNs (qNaNs) are denoted by the first bit of their trailing significand field being 0, whereas signaling NaNs (sNaNs) are de- noted by the first bit of their trailing significand field being 1. The --mmnnaann==22000088 option selects the IEEE 754-2008 encoding. In this case qNaNs are denoted by the first bit of their trailing signifi- cand field being 1, whereas sNaNs are denoted by the first bit of their trailing significand field being 0. The default is --mmnnaann==lleeggaaccyy unless GCC has been configured with ----wwiitthh--nnaann==22000088. --mmllllsscc --mmnnoo--llllsscc Use (do not use) llll, sscc, and ssyynncc instructions to implement atomic memory built-in functions. When neither option is specified, GCC uses the instructions if the target architecture supports them. --mmllllsscc is useful if the runtime environment can emulate the in- structions and --mmnnoo--llllsscc can be useful when compiling for nonstan- dard ISAs. You can make either option the default by configuring GCC with ----wwiitthh--llllsscc and ----wwiitthhoouutt--llllsscc respectively. ----wwiitthh--llllsscc is the default for some configurations; see the installation docu- mentation for details. --mmddsspp --mmnnoo--ddsspp Use (do not use) revision 1 of the MIPS DSP ASE. This option defines the preprocessor macro "__mips_dsp". It also defines "__mips_dsp_rev" to 1. --mmddsspprr22 --mmnnoo--ddsspprr22 Use (do not use) revision 2 of the MIPS DSP ASE. This option defines the preprocessor macros "__mips_dsp" and "__mips_dspr2". It also defines "__mips_dsp_rev" to 2. --mmssmmaarrttmmiippss --mmnnoo--ssmmaarrttmmiippss Use (do not use) the MIPS SmartMIPS ASE. --mmppaaiirreedd--ssiinnggllee --mmnnoo--ppaaiirreedd--ssiinnggllee Use (do not use) paired-single floating-point instructions. This option requires hardware floating-point support to be en- abled. --mmddmmxx --mmnnoo--mmddmmxx Use (do not use) MIPS Digital Media Extension instructions. This option can only be used when generating 64-bit code and requires hardware floating-point support to be enabled. --mmiippss33dd --mmnnoo--mmiippss33dd Use (do not use) the MIPS-3D ASE. The option --mmiippss33dd implies --mmppaaiirreedd--ssiinnggllee. --mmmmiiccrroommiippss --mmnnoo--mmiiccrroommiippss Generate (do not generate) microMIPS code. MicroMIPS code generation can also be controlled on a per-function basis by means of "micromips" and "nomicromips" attributes. --mmmmtt --mmnnoo--mmtt Use (do not use) MT Multithreading instructions. --mmmmccuu --mmnnoo--mmccuu Use (do not use) the MIPS MCU ASE instructions. --mmeevvaa --mmnnoo--eevvaa Use (do not use) the MIPS Enhanced Virtual Addressing instructions. --mmvviirrtt --mmnnoo--vviirrtt Use (do not use) the MIPS Virtualization (VZ) instructions. --mmxxppaa --mmnnoo--xxppaa Use (do not use) the MIPS eXtended Physical Address (XPA) instruc- tions. --mmccrrcc --mmnnoo--ccrrcc Use (do not use) the MIPS Cyclic Redundancy Check (CRC) instruc- tions. --mmggiinnvv --mmnnoo--ggiinnvv Use (do not use) the MIPS Global INValidate (GINV) instructions. --mmlloooonnggssoonn--mmmmii --mmnnoo--lloooonnggssoonn--mmmmii Use (do not use) the MIPS Loongson MultiMedia extensions Instruc- tions (MMI). --mmlloooonnggssoonn--eexxtt --mmnnoo--lloooonnggssoonn--eexxtt Use (do not use) the MIPS Loongson EXTensions (EXT) instructions. --mmlloooonnggssoonn--eexxtt22 --mmnnoo--lloooonnggssoonn--eexxtt22 Use (do not use) the MIPS Loongson EXTensions r2 (EXT2) instruc- tions. --mmlloonngg6644 Force "long" types to be 64 bits wide. See --mmlloonngg3322 for an expla- nation of the default and the way that the pointer size is deter- mined. --mmlloonngg3322 Force "long", "int", and pointer types to be 32 bits wide. The default size of "int"s, "long"s and pointers depends on the ABI. All the supported ABIs use 32-bit "int"s. The n64 ABI uses 64-bit "long"s, as does the 64-bit EABI; the others use 32-bit "long"s. Pointers are the same size as "long"s, or the same size as integer registers, whichever is smaller. --mmssyymm3322 --mmnnoo--ssyymm3322 Assume (do not assume) that all symbols have 32-bit values, regard- less of the selected ABI. This option is useful in combination with --mmaabbii==6644 and --mmnnoo--aabbiiccaallllss because it allows GCC to generate shorter and faster references to symbolic addresses. --GG _n_u_m Put definitions of externally-visible data in a small data section if that data is no bigger than _n_u_m bytes. GCC can then generate more efficient accesses to the data; see --mmggppoopptt for details. The default --GG option depends on the configuration. --mmllooccaall--ssddaattaa --mmnnoo--llooccaall--ssddaattaa Extend (do not extend) the --GG behavior to local data too, such as to static variables in C. --mmllooccaall--ssddaattaa is the default for all configurations. If the linker complains that an application is using too much small data, you might want to try rebuilding the less performance-criti- cal parts with --mmnnoo--llooccaall--ssddaattaa. You might also want to build large libraries with --mmnnoo--llooccaall--ssddaattaa, so that the libraries leave more room for the main program. --mmeexxtteerrnn--ssddaattaa --mmnnoo--eexxtteerrnn--ssddaattaa Assume (do not assume) that externally-defined data is in a small data section if the size of that data is within the --GG limit. --mmeexxtteerrnn--ssddaattaa is the default for all configurations. If you compile a module _M_o_d with --mmeexxtteerrnn--ssddaattaa --GG _n_u_m --mmggppoopptt, and _M_o_d references a variable _V_a_r that is no bigger than _n_u_m bytes, you must make sure that _V_a_r is placed in a small data section. If _V_a_r is defined by another module, you must either compile that module with a high-enough --GG setting or attach a "section" attribute to _V_a_r's definition. If _V_a_r is common, you must link the application with a high-enough --GG setting. The easiest way of satisfying these restrictions is to compile and link every module with the same --GG option. However, you may wish to build a library that supports several different small data lim- its. You can do this by compiling the library with the highest supported --GG setting and additionally using --mmnnoo--eexxtteerrnn--ssddaattaa to stop the library from making assumptions about externally-defined data. --mmggppoopptt --mmnnoo--ggppoopptt Use (do not use) GP-relative accesses for symbols that are known to be in a small data section; see --GG, --mmllooccaall--ssddaattaa and --mmeexx-- tteerrnn--ssddaattaa. --mmggppoopptt is the default for all configurations. --mmnnoo--ggppoopptt is useful for cases where the $gp register might not hold the value of "_gp". For example, if the code is part of a li- brary that might be used in a boot monitor, programs that call boot monitor routines pass an unknown value in $gp. (In such situa- tions, the boot monitor itself is usually compiled with --GG00.) --mmnnoo--ggppoopptt implies --mmnnoo--llooccaall--ssddaattaa and --mmnnoo--eexxtteerrnn--ssddaattaa. --mmeemmbbeeddddeedd--ddaattaa --mmnnoo--eemmbbeeddddeedd--ddaattaa Allocate variables to the read-only data section first if possible, then next in the small data section if possible, otherwise in data. This gives slightly slower code than the default, but reduces the amount of RAM required when executing, and thus may be preferred for some embedded systems. --mmuunniinniitt--ccoonnsstt--iinn--rrooddaattaa --mmnnoo--uunniinniitt--ccoonnsstt--iinn--rrooddaattaa Put uninitialized "const" variables in the read-only data section. This option is only meaningful in conjunction with --mmeemmbbeeddddeedd--ddaattaa. --mmccooddee--rreeaaddaabbllee==_s_e_t_t_i_n_g Specify whether GCC may generate code that reads from executable sections. There are three possible settings: --mmccooddee--rreeaaddaabbllee==yyeess Instructions may freely access executable sections. This is the default setting. --mmccooddee--rreeaaddaabbllee==ppccrreell MIPS16 PC-relative load instructions can access executable sec- tions, but other instructions must not do so. This option is useful on 4KSc and 4KSd processors when the code TLBs have the Read Inhibit bit set. It is also useful on processors that can be configured to have a dual instruction/data SRAM interface and that, like the M4K, automatically redirect PC-relative loads to the instruction RAM. --mmccooddee--rreeaaddaabbllee==nnoo Instructions must not access executable sections. This option can be useful on targets that are configured to have a dual in- struction/data SRAM interface but that (unlike the M4K) do not automatically redirect PC-relative loads to the instruction RAM. --mmsspplliitt--aaddddrreesssseess --mmnnoo--sspplliitt--aaddddrreesssseess Enable (disable) use of the "%hi()" and "%lo()" assembler reloca- tion operators. This option has been superseded by --mmeexxpplliicciitt--rree-- llooccss but is retained for backwards compatibility. --mmeexxpplliicciitt--rreellooccss --mmnnoo--eexxpplliicciitt--rreellooccss Use (do not use) assembler relocation operators when dealing with symbolic addresses. The alternative, selected by --mmnnoo--eexxpplliicciitt--rree-- llooccss, is to use assembler macros instead. --mmeexxpplliicciitt--rreellooccss is the default if GCC was configured to use an assembler that supports relocation operators. --mmcchheecckk--zzeerroo--ddiivviissiioonn --mmnnoo--cchheecckk--zzeerroo--ddiivviissiioonn Trap (do not trap) on integer division by zero. The default is --mmcchheecckk--zzeerroo--ddiivviissiioonn. --mmddiivviiddee--ttrraappss --mmddiivviiddee--bbrreeaakkss MIPS systems check for division by zero by generating either a con- ditional trap or a break instruction. Using traps results in smaller code, but is only supported on MIPS II and later. Also, some versions of the Linux kernel have a bug that prevents trap from generating the proper signal ("SIGFPE"). Use --mmddiivviiddee--ttrraappss to allow conditional traps on architectures that support them and --mmddiivviiddee--bbrreeaakkss to force the use of breaks. The default is usually --mmddiivviiddee--ttrraappss, but this can be overridden at configure time using ----wwiitthh--ddiivviiddee==bbrreeaakkss. Divide-by-zero checks can be completely disabled using --mmnnoo--cchheecckk--zzeerroo--ddiivviissiioonn. --mmllooaadd--ssttoorree--ppaaiirrss --mmnnoo--llooaadd--ssttoorree--ppaaiirrss Enable (disable) an optimization that pairs consecutive load or store instructions to enable load/store bonding. This option is enabled by default but only takes effect when the selected archi- tecture is known to support bonding. --mmuunnaalliiggnneedd--aacccceessss --mmnnoo--uunnaalliiggnneedd--aacccceessss Enable (disable) direct unaligned access for MIPS Release 6. MIPSr6 requires load/store unaligned-access support, by hardware or trap&emulate. So --mmnnoo--uunnaalliiggnneedd--aacccceessss may be needed by kernel. --mmmmeemmccppyy --mmnnoo--mmeemmccppyy Force (do not force) the use of "memcpy" for non-trivial block moves. The default is --mmnnoo--mmeemmccppyy, which allows GCC to inline most constant-sized copies. --mmlloonngg--ccaallllss --mmnnoo--lloonngg--ccaallllss Disable (do not disable) use of the "jal" instruction. Calling functions using "jal" is more efficient but requires the caller and callee to be in the same 256 megabyte segment. This option has no effect on abicalls code. The default is --mmnnoo--lloonngg--ccaallllss. --mmmmaadd --mmnnoo--mmaadd Enable (disable) use of the "mad", "madu" and "mul" instructions, as provided by the R4650 ISA. --mmiimmaadddd --mmnnoo--iimmaadddd Enable (disable) use of the "madd" and "msub" integer instructions. The default is --mmiimmaadddd on architectures that support "madd" and "msub" except for the 74k architecture where it was found to gener- ate slower code. --mmffuusseedd--mmaadddd --mmnnoo--ffuusseedd--mmaadddd Enable (disable) use of the floating-point multiply-accumulate in- structions, when they are available. The default is --mmffuusseedd--mmaadddd. On the R8000 CPU when multiply-accumulate instructions are used, the intermediate product is calculated to infinite precision and is not subject to the FCSR Flush to Zero bit. This may be undesirable in some circumstances. On other processors the result is numeri- cally identical to the equivalent computation using separate multi- ply, add, subtract and negate instructions. --nnooccpppp Tell the MIPS assembler to not run its preprocessor over user as- sembler files (with a ..ss suffix) when assembling them. --mmffiixx--2244kk --mmnnoo--ffiixx--2244kk Work around the 24K E48 (lost data on stores during refill) errata. The workarounds are implemented by the assembler rather than by GCC. --mmffiixx--rr44000000 --mmnnoo--ffiixx--rr44000000 Work around certain R4000 CPU errata: - A double-word or a variable shift may give an incorrect result if executed immediately after starting an integer division. - A double-word or a variable shift may give an incorrect result if executed while an integer multiplication is in progress. - An integer division may give an incorrect result if started in a delay slot of a taken branch or a jump. --mmffiixx--rr44440000 --mmnnoo--ffiixx--rr44440000 Work around certain R4400 CPU errata: - A double-word or a variable shift may give an incorrect result if executed immediately after starting an integer division. --mmffiixx--rr1100000000 --mmnnoo--ffiixx--rr1100000000 Work around certain R10000 errata: - "ll"/"sc" sequences may not behave atomically on revisions prior to 3.0. They may deadlock on revisions 2.6 and earlier. This option can only be used if the target architecture supports branch-likely instructions. --mmffiixx--rr1100000000 is the default when --mmaarrcchh==rr1100000000 is used; --mmnnoo--ffiixx--rr1100000000 is the default otherwise. --mmffiixx--rr55990000 --mmnnoo--ffiixx--rr55990000 Do not attempt to schedule the preceding instruction into the delay slot of a branch instruction placed at the end of a short loop of six instructions or fewer and always schedule a "nop" instruction there instead. The short loop bug under certain conditions causes loops to execute only once or twice, due to a hardware bug in the R5900 chip. The workaround is implemented by the assembler rather than by GCC. --mmffiixx--rrmm77000000 --mmnnoo--ffiixx--rrmm77000000 Work around the RM7000 "dmult"/"dmultu" errata. The workarounds are implemented by the assembler rather than by GCC. --mmffiixx--vvrr44112200 --mmnnoo--ffiixx--vvrr44112200 Work around certain VR4120 errata: - "dmultu" does not always produce the correct result. - "div" and "ddiv" do not always produce the correct result if one of the operands is negative. The workarounds for the division errata rely on special functions in _l_i_b_g_c_c_._a. At present, these functions are only provided by the "mips64vr*-elf" configurations. Other VR4120 errata require a NOP to be inserted between certain pairs of instructions. These errata are handled by the assembler, not by GCC itself. --mmffiixx--vvrr44113300 Work around the VR4130 "mflo"/"mfhi" errata. The workarounds are implemented by the assembler rather than by GCC, although GCC avoids using "mflo" and "mfhi" if the VR4130 "macc", "macchi", "dmacc" and "dmacchi" instructions are available instead. --mmffiixx--ssbb11 --mmnnoo--ffiixx--ssbb11 Work around certain SB-1 CPU core errata. (This flag currently works around the SB-1 revision 2 "F1" and "F2" floating-point er- rata.) --mmrr1100kk--ccaacchhee--bbaarrrriieerr==_s_e_t_t_i_n_g Specify whether GCC should insert cache barriers to avoid the side effects of speculation on R10K processors. In common with many processors, the R10K tries to predict the out- come of a conditional branch and speculatively executes instruc- tions from the "taken" branch. It later aborts these instructions if the predicted outcome is wrong. However, on the R10K, even aborted instructions can have side effects. This problem only affects kernel stores and, depending on the sys- tem, kernel loads. As an example, a speculatively-executed store may load the target memory into cache and mark the cache line as dirty, even if the store itself is later aborted. If a DMA opera- tion writes to the same area of memory before the "dirty" line is flushed, the cached data overwrites the DMA-ed data. See the R10K processor manual for a full description, including other potential problems. One workaround is to insert cache barrier instructions before every memory access that might be speculatively executed and that might have side effects even if aborted. --mmrr1100kk--ccaacchhee--bbaarrrriieerr==_s_e_t_t_i_n_g controls GCC's implementation of this workaround. It assumes that aborted accesses to any byte in the following regions does not have side effects: 1. the memory occupied by the current function's stack frame; 2. the memory occupied by an incoming stack argument; 3. the memory occupied by an object with a link-time-constant ad- dress. It is the kernel's responsibility to ensure that speculative ac- cesses to these regions are indeed safe. If the input program contains a function declaration such as: void foo (void); then the implementation of "foo" must allow "j foo" and "jal foo" to be executed speculatively. GCC honors this restriction for functions it compiles itself. It expects non-GCC functions (such as hand-written assembly code) to do the same. The option has three forms: --mmrr1100kk--ccaacchhee--bbaarrrriieerr==llooaadd--ssttoorree Insert a cache barrier before a load or store that might be speculatively executed and that might have side effects even if aborted. --mmrr1100kk--ccaacchhee--bbaarrrriieerr==ssttoorree Insert a cache barrier before a store that might be specula- tively executed and that might have side effects even if aborted. --mmrr1100kk--ccaacchhee--bbaarrrriieerr==nnoonnee Disable the insertion of cache barriers. This is the default setting. --mmfflluusshh--ffuunncc==_f_u_n_c --mmnnoo--fflluusshh--ffuunncc Specifies the function to call to flush the I and D caches, or to not call any such function. If called, the function must take the same arguments as the common "_flush_func", that is, the address of the memory range for which the cache is being flushed, the size of the memory range, and the number 3 (to flush both caches). The de- fault depends on the target GCC was configured for, but commonly is either "_flush_func" or "__cpu_flush". mmbbrraanncchh--ccoosstt==_n_u_m Set the cost of branches to roughly _n_u_m "simple" instructions. This cost is only a heuristic and is not guaranteed to produce con- sistent results across releases. A zero cost redundantly selects the default, which is based on the --mmttuunnee setting. --mmbbrraanncchh--lliikkeellyy --mmnnoo--bbrraanncchh--lliikkeellyy Enable or disable use of Branch Likely instructions, regardless of the default for the selected architecture. By default, Branch Likely instructions may be generated if they are supported by the selected architecture. An exception is for the MIPS32 and MIPS64 architectures and processors that implement those architectures; for those, Branch Likely instructions are not be generated by de- fault because the MIPS32 and MIPS64 architectures specifically dep- recate their use. --mmccoommppaacctt--bbrraanncchheess==nneevveerr --mmccoommppaacctt--bbrraanncchheess==ooppttiimmaall --mmccoommppaacctt--bbrraanncchheess==aallwwaayyss These options control which form of branches will be generated. The default is --mmccoommppaacctt--bbrraanncchheess==ooppttiimmaall. The --mmccoommppaacctt--bbrraanncchheess==nneevveerr option ensures that compact branch in- structions will never be generated. The --mmccoommppaacctt--bbrraanncchheess==aallwwaayyss option ensures that a compact branch instruction will be generated if available. If a compact branch instruction is not available, a delay slot form of the branch will be used instead. This option is supported from MIPS Release 6 onwards. The --mmccoommppaacctt--bbrraanncchheess==ooppttiimmaall option will cause a delay slot branch to be used if one is available in the current ISA and the delay slot is successfully filled. If the delay slot is not filled, a compact branch will be chosen if one is available. --mmffpp--eexxcceeppttiioonnss --mmnnoo--ffpp--eexxcceeppttiioonnss Specifies whether FP exceptions are enabled. This affects how FP instructions are scheduled for some processors. The default is that FP exceptions are enabled. For instance, on the SB-1, if FP exceptions are disabled, and we are emitting 64-bit code, then we can use both FP pipes. Other- wise, we can only use one FP pipe. --mmvvrr44113300--aalliiggnn --mmnnoo--vvrr44113300--aalliiggnn The VR4130 pipeline is two-way superscalar, but can only issue two instructions together if the first one is 8-byte aligned. When this option is enabled, GCC aligns pairs of instructions that it thinks should execute in parallel. This option only has an effect when optimizing for the VR4130. It normally makes code faster, but at the expense of making it bigger. It is enabled by default at optimization level --OO33. --mmssyynnccii --mmnnoo--ssyynnccii Enable (disable) generation of "synci" instructions on architec- tures that support it. The "synci" instructions (if enabled) are generated when "__builtin___clear_cache" is compiled. This option defaults to --mmnnoo--ssyynnccii, but the default can be overrid- den by configuring GCC with ----wwiitthh--ssyynnccii. When compiling code for single processor systems, it is generally safe to use "synci". However, on many multi-core (SMP) systems, it does not invalidate the instruction caches on all cores and may lead to undefined behavior. --mmrreellaaxx--ppiicc--ccaallllss --mmnnoo--rreellaaxx--ppiicc--ccaallllss Try to turn PIC calls that are normally dispatched via register $25 into direct calls. This is only possible if the linker can resolve the destination at link time and if the destination is within range for a direct call. --mmrreellaaxx--ppiicc--ccaallllss is the default if GCC was configured to use an assembler and a linker that support the ".reloc" assembly directive and --mmeexxpplliicciitt--rreellooccss is in effect. With --mmnnoo--eexxpplliicciitt--rreellooccss, this optimization can be performed by the assembler and the linker alone without help from the compiler. --mmmmccoouunntt--rraa--aaddddrreessss --mmnnoo--mmccoouunntt--rraa--aaddddrreessss Emit (do not emit) code that allows "_mcount" to modify the calling function's return address. When enabled, this option extends the usual "_mcount" interface with a new _r_a_-_a_d_d_r_e_s_s parameter, which has type "intptr_t *" and is passed in register $12. "_mcount" can then modify the return address by doing both of the following: * Returning the new address in register $31. * Storing the new address in "*_r_a_-_a_d_d_r_e_s_s_", if _r_a_-_a_d_d_r_e_s_s is non- null. The default is --mmnnoo--mmccoouunntt--rraa--aaddddrreessss. --mmffrraammee--hheeaaddeerr--oopptt --mmnnoo--ffrraammee--hheeaaddeerr--oopptt Enable (disable) frame header optimization in the o32 ABI. When using the o32 ABI, calling functions will allocate 16 bytes on the stack for the called function to write out register arguments. When enabled, this optimization will suppress the allocation of the frame header if it can be determined that it is unused. This optimization is off by default at all optimization levels. --mmllxxcc11--ssxxcc11 --mmnnoo--llxxcc11--ssxxcc11 When applicable, enable (disable) the generation of "lwxc1", "swxc1", "ldxc1", "sdxc1" instructions. Enabled by default. --mmmmaadddd44 --mmnnoo--mmaadddd44 When applicable, enable (disable) the generation of 4-operand "madd.s", "madd.d" and related instructions. Enabled by default. _M_M_I_X _O_p_t_i_o_n_s These options are defined for the MMIX: --mmlliibbffuunnccss --mmnnoo--lliibbffuunnccss Specify that intrinsic library functions are being compiled, pass- ing all values in registers, no matter the size. --mmeeppssiilloonn --mmnnoo--eeppssiilloonn Generate floating-point comparison instructions that compare with respect to the "rE" epsilon register. --mmaabbii==mmmmiixxwwaarree --mmaabbii==ggnnuu Generate code that passes function parameters and return values that (in the called function) are seen as registers $0 and up, as opposed to the GNU ABI which uses global registers $231 and up. --mmzzeerroo--eexxtteenndd --mmnnoo--zzeerroo--eexxtteenndd When reading data from memory in sizes shorter than 64 bits, use (do not use) zero-extending load instructions by default, rather than sign-extending ones. --mmkknnuutthhddiivv --mmnnoo--kknnuutthhddiivv Make the result of a division yielding a remainder have the same sign as the divisor. With the default, --mmnnoo--kknnuutthhddiivv, the sign of the remainder follows the sign of the dividend. Both methods are arithmetically valid, the latter being almost exclusively used. --mmttoopplleevveell--ssyymmbboollss --mmnnoo--ttoopplleevveell--ssyymmbboollss Prepend (do not prepend) a :: to all global symbols, so the assembly code can be used with the "PREFIX" assembly directive. --mmeellff Generate an executable in the ELF format, rather than the default mmmmoo format used by the mmmmiixx simulator. --mmbbrraanncchh--pprreeddiicctt --mmnnoo--bbrraanncchh--pprreeddiicctt Use (do not use) the probable-branch instructions, when static branch prediction indicates a probable branch. --mmbbaassee--aaddddrreesssseess --mmnnoo--bbaassee--aaddddrreesssseess Generate (do not generate) code that uses _b_a_s_e _a_d_d_r_e_s_s_e_s. Using a base address automatically generates a request (handled by the as- sembler and the linker) for a constant to be set up in a global register. The register is used for one or more base address re- quests within the range 0 to 255 from the value held in the regis- ter. The generally leads to short and fast code, but the number of different data items that can be addressed is limited. This means that a program that uses lots of static data may require --mmnnoo--bbaassee--aaddddrreesssseess. --mmssiinnggllee--eexxiitt --mmnnoo--ssiinnggllee--eexxiitt Force (do not force) generated code to have a single exit point in each function. _M_N_1_0_3_0_0 _O_p_t_i_o_n_s These --mm options are defined for Matsushita MN10300 architectures: --mmmmuulltt--bbuugg Generate code to avoid bugs in the multiply instructions for the MN10300 processors. This is the default. --mmnnoo--mmuulltt--bbuugg Do not generate code to avoid bugs in the multiply instructions for the MN10300 processors. --mmaamm3333 Generate code using features specific to the AM33 processor. --mmnnoo--aamm3333 Do not generate code using features specific to the AM33 processor. This is the default. --mmaamm3333--22 Generate code using features specific to the AM33/2.0 processor. --mmaamm3344 Generate code using features specific to the AM34 processor. --mmttuunnee==_c_p_u_-_t_y_p_e Use the timing characteristics of the indicated CPU type when scheduling instructions. This does not change the targeted proces- sor type. The CPU type must be one of mmnn1100330000, aamm3333, aamm3333--22 or aamm3344. --mmrreettuurrnn--ppooiinntteerr--oonn--dd00 When generating a function that returns a pointer, return the pointer in both "a0" and "d0". Otherwise, the pointer is returned only in "a0", and attempts to call such functions without a proto- type result in errors. Note that this option is on by default; use --mmnnoo--rreettuurrnn--ppooiinntteerr--oonn--dd00 to disable it. --mmnnoo--ccrrtt00 Do not link in the C run-time initialization object file. --mmrreellaaxx Indicate to the linker that it should perform a relaxation opti- mization pass to shorten branches, calls and absolute memory ad- dresses. This option only has an effect when used on the command line for the final link step. This option makes symbolic debugging impossible. --mmlliiww Allow the compiler to generate _L_o_n_g _I_n_s_t_r_u_c_t_i_o_n _W_o_r_d instructions if the target is the AAMM3333 or later. This is the default. This op- tion defines the preprocessor macro "__LIW__". --mmnnoo--lliiww Do not allow the compiler to generate _L_o_n_g _I_n_s_t_r_u_c_t_i_o_n _W_o_r_d in- structions. This option defines the preprocessor macro "__NO_LIW__". --mmsseettllbb Allow the compiler to generate the _S_E_T_L_B and _L_c_c instructions if the target is the AAMM3333 or later. This is the default. This option defines the preprocessor macro "__SETLB__". --mmnnoo--sseettllbb Do not allow the compiler to generate _S_E_T_L_B or _L_c_c instructions. This option defines the preprocessor macro "__NO_SETLB__". _M_o_x_i_e _O_p_t_i_o_n_s --mmeebb Generate big-endian code. This is the default for mmooxxiiee--**--** con- figurations. --mmeell Generate little-endian code. --mmmmuull..xx Generate mul.x and umul.x instructions. This is the default for mmooxxiieebbooxx--**--** configurations. --mmnnoo--ccrrtt00 Do not link in the C run-time initialization object file. _M_S_P_4_3_0 _O_p_t_i_o_n_s These options are defined for the MSP430: --mmaassmm--hheexx Force assembly output to always use hex constants. Normally such constants are signed decimals, but this option is available for testsuite and/or aesthetic purposes. --mmmmccuu== Select the MCU to target. This is used to create a C preprocessor symbol based upon the MCU name, converted to upper case and pre- and post-fixed with ____. This in turn is used by the _m_s_p_4_3_0_._h header file to select an MCU-specific supplementary header file. The option also sets the ISA to use. If the MCU name is one that is known to only support the 430 ISA then that is selected, other- wise the 430X ISA is selected. A generic MCU name of mmsspp443300 can also be used to select the 430 ISA. Similarly the generic mmsspp443300xx MCU name selects the 430X ISA. In addition an MCU-specific linker script is added to the linker command line. The script's name is the name of the MCU with _._l_d appended. Thus specifying --mmmmccuu==xxxxxx on the ggcccc command line de- fines the C preprocessor symbol "__XXX__" and cause the linker to search for a script called _x_x_x_._l_d. The ISA and hardware multiply supported for the different MCUs is hard-coded into GCC. However, an external ddeevviicceess..ccssvv file can be used to extend device support beyond those that have been hard-coded. GCC searches for the ddeevviicceess..ccssvv file using the following methods in the given precedence order, where the first method takes precen- dence over the second which takes precedence over the third. Include path specified with "-I" and "-L" ddeevviicceess..ccssvv will be searched for in each of the directories specified by include paths and linker library search paths. Path specified by the environment variable MMSSPP443300__GGCCCC__IINNCCLLUUDDEE__DDIIRR Define the value of the global environment variable MMSSPP443300__GGCCCC__IINNCCLLUUDDEE__DDIIRR to the full path to the directory con- taining devices.csv, and GCC will search this directory for de- vices.csv. If devices.csv is found, this directory will also be registered as an include path, and linker library path. Header files and linker scripts in this directory can therefore be used without manually specifying "-I" and "-L" on the com- mand line. The mmsspp443300--eellff{{,,bbaarree}}//iinncclluuddee//ddeevviicceess directory Finally, GCC will examine mmsspp443300--eellff{{,,bbaarree}}//iinncclluuddee//ddeevviicceess from the toolchain root directory. This directory does not ex- ist in a default installation, but if the user has created it and copied ddeevviicceess..ccssvv there, then the MCU data will be read. As above, this directory will also be registered as an include path, and linker library path. If none of the above search methods find ddeevviicceess..ccssvv, then the hard-coded MCU data is used. --mmwwaarrnn--mmccuu --mmnnoo--wwaarrnn--mmccuu This option enables or disables warnings about conflicts between the MCU name specified by the --mmmmccuu option and the ISA set by the --mmccppuu option and/or the hardware multiply support set by the --mmhhww-- mmuulltt option. It also toggles warnings about unrecognized MCU names. This option is on by default. --mmccppuu== Specifies the ISA to use. Accepted values are mmsspp443300, mmsspp443300xx and mmsspp443300xxvv22. This option is deprecated. The --mmmmccuu== option should be used to select the ISA. --mmssiimm Link to the simulator runtime libraries and linker script. Over- rides any scripts that would be selected by the --mmmmccuu== option. --mmllaarrggee Use large-model addressing (20-bit pointers, 20-bit "size_t"). --mmssmmaallll Use small-model addressing (16-bit pointers, 16-bit "size_t"). --mmrreellaaxx This option is passed to the assembler and linker, and allows the linker to perform certain optimizations that cannot be done until the final link. mmhhwwmmuulltt== Describes the type of hardware multiply supported by the target. Accepted values are nnoonnee for no hardware multiply, 1166bbiitt for the original 16-bit-only multiply supported by early MCUs. 3322bbiitt for the 16/32-bit multiply supported by later MCUs and ff55sseerriieess for the 16/32-bit multiply supported by F5-series MCUs. A value of aauuttoo can also be given. This tells GCC to deduce the hardware multiply support based upon the MCU name provided by the --mmmmccuu option. If no --mmmmccuu option is specified or if the MCU name is not recognized then no hardware multiply support is assumed. "auto" is the de- fault setting. Hardware multiplies are normally performed by calling a library routine. This saves space in the generated code. When compiling at --OO33 or higher however the hardware multiplier is invoked inline. This makes for bigger, but faster code. The hardware multiply routines disable interrupts whilst running and restore the previous interrupt state when they finish. This makes them safe to use inside interrupt handlers as well as in nor- mal code. --mmiinnrrtt Enable the use of a minimum runtime environment - no static ini- tializers or constructors. This is intended for memory-constrained devices. The compiler includes special symbols in some objects that tell the linker and runtime which code fragments are required. --mmttiinnyy--pprriinnttff Enable reduced code size "printf" and "puts" library functions. The ttiinnyy implementations of these functions are not reentrant, so must be used with caution in multi-threaded applications. Support for streams has been removed and the string to be printed will always be sent to stdout via the "write" syscall. The string is not buffered before it is sent to write. This option requires Newlib Nano IO, so GCC must be configured with ----eennaabbllee--nneewwlliibb--nnaannoo--ffoorrmmaatttteedd--iioo. --mmmmaaxx--iinnlliinnee--sshhiifftt== This option takes an integer between 0 and 64 inclusive, and sets the maximum number of inline shift instructions which should be emitted to perform a shift operation by a constant amount. When this value needs to be exceeded, an mspabi helper function is used instead. The default value is 4. This only affects cases where a shift by multiple positions cannot be completed with a single instruction (e.g. all shifts >1 on the 430 ISA). Shifts of a 32-bit value are at least twice as costly, so the value passed for this option is divided by 2 and the resulting value used instead. --mmccooddee--rreeggiioonn== --mmddaattaa--rreeggiioonn== These options tell the compiler where to place functions and data that do not have one of the "lower", "upper", "either" or "section" attributes. Possible values are "lower", "upper", "either" or "any". The first three behave like the corresponding attribute. The fourth possible value - "any" - is the default. It leaves placement entirely up to the linker script and how it assigns the standard sections (".text", ".data", etc) to the memory regions. --mmssiilliiccoonn--eerrrraattaa== This option passes on a request to assembler to enable the fixes for the named silicon errata. --mmssiilliiccoonn--eerrrraattaa--wwaarrnn== This option passes on a request to the assembler to enable warning messages when a silicon errata might need to be applied. --mmwwaarrnn--ddeevviicceess--ccssvv --mmnnoo--wwaarrnn--ddeevviicceess--ccssvv Warn if ddeevviicceess..ccssvv is not found or there are problem parsing it (default: on). _N_D_S_3_2 _O_p_t_i_o_n_s These options are defined for NDS32 implementations: --mmbbiigg--eennddiiaann Generate code in big-endian mode. --mmlliittttllee--eennddiiaann Generate code in little-endian mode. --mmrreedduucceedd--rreeggss Use reduced-set registers for register allocation. --mmffuullll--rreeggss Use full-set registers for register allocation. --mmccmmoovv Generate conditional move instructions. --mmnnoo--ccmmoovv Do not generate conditional move instructions. --mmeexxtt--ppeerrff Generate performance extension instructions. --mmnnoo--eexxtt--ppeerrff Do not generate performance extension instructions. --mmeexxtt--ppeerrff22 Generate performance extension 2 instructions. --mmnnoo--eexxtt--ppeerrff22 Do not generate performance extension 2 instructions. --mmeexxtt--ssttrriinngg Generate string extension instructions. --mmnnoo--eexxtt--ssttrriinngg Do not generate string extension instructions. --mmvv33ppuusshh Generate v3 push25/pop25 instructions. --mmnnoo--vv33ppuusshh Do not generate v3 push25/pop25 instructions. --mm1166--bbiitt Generate 16-bit instructions. --mmnnoo--1166--bbiitt Do not generate 16-bit instructions. --mmiissrr--vveeccttoorr--ssiizzee==_n_u_m Specify the size of each interrupt vector, which must be 4 or 16. --mmccaacchhee--bblloocckk--ssiizzee==_n_u_m Specify the size of each cache block, which must be a power of 2 between 4 and 512. --mmaarrcchh==_a_r_c_h Specify the name of the target architecture. --mmccmmooddeell==_c_o_d_e_-_m_o_d_e_l Set the code model to one of ssmmaallll All the data and read-only data segments must be within 512KB addressing space. The text segment must be within 16MB ad- dressing space. mmeeddiiuumm The data segment must be within 512KB while the read-only data segment can be within 4GB addressing space. The text segment should be still within 16MB addressing space. llaarrggee All the text and data segments can be within 4GB addressing space. --mmccttoorr--ddttoorr Enable constructor/destructor feature. --mmrreellaaxx Guide linker to relax instructions. _N_i_o_s _I_I _O_p_t_i_o_n_s These are the options defined for the Altera Nios II processor. --GG _n_u_m Put global and static objects less than or equal to _n_u_m bytes into the small data or BSS sections instead of the normal data or BSS sections. The default value of _n_u_m is 8. --mmggppoopptt==_o_p_t_i_o_n --mmggppoopptt --mmnnoo--ggppoopptt Generate (do not generate) GP-relative accesses. The following _o_p_- _t_i_o_n names are recognized: nnoonnee Do not generate GP-relative accesses. llooccaall Generate GP-relative accesses for small data objects that are not external, weak, or uninitialized common symbols. Also use GP-relative addressing for objects that have been explicitly placed in a small data section via a "section" attribute. gglloobbaall As for llooccaall, but also generate GP-relative accesses for small data objects that are external, weak, or common. If you use this option, you must ensure that all parts of your program (including libraries) are compiled with the same --GG setting. ddaattaa Generate GP-relative accesses for all data objects in the pro- gram. If you use this option, the entire data and BSS segments of your program must fit in 64K of memory and you must use an appropriate linker script to allocate them within the address- able range of the global pointer. aallll Generate GP-relative addresses for function pointers as well as data pointers. If you use this option, the entire text, data, and BSS segments of your program must fit in 64K of memory and you must use an appropriate linker script to allocate them within the addressable range of the global pointer. --mmggppoopptt is equivalent to --mmggppoopptt==llooccaall, and --mmnnoo--ggppoopptt is equiva- lent to --mmggppoopptt==nnoonnee. The default is --mmggppoopptt except when --ffppiicc or --ffPPIICC is specified to generate position-independent code. Note that the Nios II ABI does not permit GP-relative accesses from shared libraries. You may need to specify --mmnnoo--ggppoopptt explicitly when building pro- grams that include large amounts of small data, including large GOT data sections. In this case, the 16-bit offset for GP-relative ad- dressing may not be large enough to allow access to the entire small data section. --mmggpprreell--sseecc==_r_e_g_e_x_p This option specifies additional section names that can be accessed via GP-relative addressing. It is most useful in conjunction with "section" attributes on variable declarations and a custom linker script. The _r_e_g_e_x_p is a POSIX Extended Regular Expression. This option does not affect the behavior of the --GG option, and the specified sections are in addition to the standard ".sdata" and ".sbss" small-data sections that are recognized by --mmggppoopptt. --mmrr00rreell--sseecc==_r_e_g_e_x_p This option specifies names of sections that can be accessed via a 16-bit offset from "r0"; that is, in the low 32K or high 32K of the 32-bit address space. It is most useful in conjunction with "sec- tion" attributes on variable declarations and a custom linker script. The _r_e_g_e_x_p is a POSIX Extended Regular Expression. In contrast to the use of GP-relative addressing for small data, zero-based addressing is never generated by default and there are no conventional section names used in standard linker scripts for sections in the low or high areas of memory. --mmeell --mmeebb Generate little-endian (default) or big-endian (experimental) code, respectively. --mmaarrcchh==_a_r_c_h This specifies the name of the target Nios II architecture. GCC uses this name to determine what kind of instructions it can emit when generating assembly code. Permissible names are: rr11, rr22. The preprocessor macro "__nios2_arch__" is available to programs, with value 1 or 2, indicating the targeted ISA level. --mmbbyyppaassss--ccaacchhee --mmnnoo--bbyyppaassss--ccaacchhee Force all load and store instructions to always bypass cache by us- ing I/O variants of the instructions. The default is not to bypass the cache. --mmnnoo--ccaacchhee--vvoollaattiillee --mmccaacchhee--vvoollaattiillee Volatile memory access bypass the cache using the I/O variants of the load and store instructions. The default is not to bypass the cache. --mmnnoo--ffaasstt--ssww--ddiivv --mmffaasstt--ssww--ddiivv Do not use table-based fast divide for small numbers. The default is to use the fast divide at --OO33 and above. --mmnnoo--hhww--mmuull --mmhhww--mmuull --mmnnoo--hhww--mmuullxx --mmhhww--mmuullxx --mmnnoo--hhww--ddiivv --mmhhww--ddiivv Enable or disable emitting "mul", "mulx" and "div" family of in- structions by the compiler. The default is to emit "mul" and not emit "div" and "mulx". --mmbbmmxx --mmnnoo--bbmmxx --mmccddxx --mmnnoo--ccddxx Enable or disable generation of Nios II R2 BMX (bit manipulation) and CDX (code density) instructions. Enabling these instructions also requires --mmaarrcchh==rr22. Since these instructions are optional ex- tensions to the R2 architecture, the default is not to emit them. --mmccuussttoomm--_i_n_s_n==_N --mmnnoo--ccuussttoomm--_i_n_s_n Each --mmccuussttoomm--_i_n_s_n==_N option enables use of a custom instruction with encoding _N when generating code that uses _i_n_s_n. For example, --mmccuussttoomm--ffaaddddss==225533 generates custom instruction 253 for single-pre- cision floating-point add operations instead of the default behav- ior of using a library call. The following values of _i_n_s_n are supported. Except as otherwise noted, floating-point operations are expected to be implemented with normal IEEE 754 semantics and correspond directly to the C op- erators or the equivalent GCC built-in functions. Single-precision floating point: ffaaddddss, ffssuubbss, ffddiivvss, ffmmuullss Binary arithmetic operations. ffnneeggss Unary negation. ffaabbssss Unary absolute value. ffccmmppeeqqss, ffccmmppggeess, ffccmmppggttss, ffccmmpplleess, ffccmmppllttss, ffccmmppnneess Comparison operations. ffmmiinnss, ffmmaaxxss Floating-point minimum and maximum. These instructions are only generated if --ffffiinniittee--mmaatthh--oonnllyy is specified. ffssqqrrttss Unary square root operation. ffccoossss, ffssiinnss, ffttaannss, ffaattaannss, ffeexxppss, ffllooggss Floating-point trigonometric and exponential functions. These instructions are only generated if --ffuunnssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss is also specified. Double-precision floating point: ffaadddddd, ffssuubbdd, ffddiivvdd, ffmmuulldd Binary arithmetic operations. ffnneeggdd Unary negation. ffaabbssdd Unary absolute value. ffccmmppeeqqdd, ffccmmppggeedd, ffccmmppggttdd, ffccmmpplleedd, ffccmmppllttdd, ffccmmppnneedd Comparison operations. ffmmiinndd, ffmmaaxxdd Double-precision minimum and maximum. These instructions are only generated if --ffffiinniittee--mmaatthh--oonnllyy is specified. ffssqqrrttdd Unary square root operation. ffccoossdd, ffssiinndd, ffttaanndd, ffaattaanndd, ffeexxppdd, ffllooggdd Double-precision trigonometric and exponential functions. These instructions are only generated if --ffuunnssaaffee--mmaatthh--ooppttii-- mmiizzaattiioonnss is also specified. Conversions: ffeexxttssdd Conversion from single precision to double precision. ffttrruunnccddss Conversion from double precision to single precision. ffiixxssii, ffiixxssuu, ffiixxddii, ffiixxdduu Conversion from floating point to signed or unsigned integer types, with truncation towards zero. rroouunndd Conversion from single-precision floating point to signed inte- ger, rounding to the nearest integer and ties away from zero. This corresponds to the "__builtin_lroundf" function when --ffnnoo--mmaatthh--eerrrrnnoo is used. ffllooaattiiss, ffllooaattuuss, ffllooaattiidd, ffllooaattuudd Conversion from signed or unsigned integer types to floating- point types. In addition, all of the following transfer instructions for inter- nal registers X and Y must be provided to use any of the double- precision floating-point instructions. Custom instructions taking two double-precision source operands expect the first operand in the 64-bit register X. The other operand (or only operand of a unary operation) is given to the custom arithmetic instruction with the least significant half in source register _s_r_c_1 and the most significant half in _s_r_c_2. A custom instruction that returns a dou- ble-precision result returns the most significant 32 bits in the destination register and the other half in 32-bit register Y. GCC automatically generates the necessary code sequences to write reg- ister X and/or read register Y when double-precision floating-point instructions are used. ffwwrrxx Write _s_r_c_1 into the least significant half of X and _s_r_c_2 into the most significant half of X. ffwwrryy Write _s_r_c_1 into Y. ffrrddxxhhii, ffrrddxxlloo Read the most or least (respectively) significant half of X and store it in _d_e_s_t. ffrrddyy Read the value of Y and store it into _d_e_s_t. Note that you can gain more local control over generation of Nios II custom instructions by using the "target("custom-_i_n_s_n_=_N_"_)_" and "target("no-custom-_i_n_s_n_"_)_" function attributes or pragmas. --mmccuussttoomm--ffppuu--ccffgg==_n_a_m_e This option enables a predefined, named set of custom instruction encodings (see --mmccuussttoomm--_i_n_s_n above). Currently, the following sets are defined: --mmccuussttoomm--ffppuu--ccffgg==6600--11 is equivalent to: --mmccuussttoomm--ffmmuullss==225522 --mmccuuss-- ttoomm--ffaaddddss==225533 --mmccuussttoomm--ffssuubbss==225544 --ffssiinnggllee--pprreecciissiioonn--ccoonnssttaanntt --mmccuussttoomm--ffppuu--ccffgg==6600--22 is equivalent to: --mmccuussttoomm--ffmmuullss==225522 --mmccuuss-- ttoomm--ffaaddddss==225533 --mmccuussttoomm--ffssuubbss==225544 --mmccuussttoomm--ffddiivvss==225555 --ffssiinnggllee--pprreeccii-- ssiioonn--ccoonnssttaanntt --mmccuussttoomm--ffppuu--ccffgg==7722--33 is equivalent to: --mmccuussttoomm--ffllooaattuuss==224433 --mmccuuss-- ttoomm--ffiixxssii==224444 --mmccuussttoomm--ffllooaattiiss==224455 --mmccuussttoomm--ffccmmppggttss==224466 --mmccuuss-- ttoomm--ffccmmpplleess==224499 --mmccuussttoomm--ffccmmppeeqqss==225500 --mmccuussttoomm--ffccmmppnneess==225511 --mmccuuss-- ttoomm--ffmmuullss==225522 --mmccuussttoomm--ffaaddddss==225533 --mmccuussttoomm--ffssuubbss==225544 --mmccuuss-- ttoomm--ffddiivvss==225555 --ffssiinnggllee--pprreecciissiioonn--ccoonnssttaanntt --mmccuussttoomm--ffppuu--ccffgg==ffpphh22 is equivalent to: --mmccuussttoomm--ffaabbssss==222244 --mmccuuss-- ttoomm--ffnneeggss==222255 --mmccuussttoomm--ffccmmppnneess==222266 --mmccuussttoomm--ffccmmppeeqqss==222277 --mmccuuss-- ttoomm--ffccmmppggeess==222288 --mmccuussttoomm--ffccmmppggttss==222299 --mmccuussttoomm--ffccmmpplleess==223300 --mmccuuss-- ttoomm--ffccmmppllttss==223311 --mmccuussttoomm--ffmmaaxxss==223322 --mmccuussttoomm--ffmmiinnss==223333 --mmccuuss-- ttoomm--rroouunndd==224488 --mmccuussttoomm--ffiixxssii==224499 --mmccuussttoomm--ffllooaattiiss==225500 --mmccuuss-- ttoomm--ffssqqrrttss==225511 --mmccuussttoomm--ffmmuullss==225522 --mmccuussttoomm--ffaaddddss==225533 --mmccuuss-- ttoomm--ffssuubbss==225544 --mmccuussttoomm--ffddiivvss==225555 Custom instruction assignments given by individual --mmccuussttoomm--_i_n_s_n== options override those given by --mmccuussttoomm--ffppuu--ccffgg==, regardless of the order of the options on the command line. Note that you can gain more local control over selection of a FPU configuration by using the "target("custom-fpu-cfg=_n_a_m_e_"_)_" function attribute or pragma. The name _f_p_h_2 is an abbreviation for _N_i_o_s _I_I _F_l_o_a_t_i_n_g _P_o_i_n_t _H_a_r_d_- _w_a_r_e _2 _C_o_m_p_o_n_e_n_t. Please note that the custom instructions enabled by --mmccuussttoomm--ffmmiinnss==223333 and --mmccuussttoomm--ffmmaaxxss==223344 are only generated if --ffffiinniittee--mmaatthh--oonnllyy is specified. The custom instruction enabled by --mmccuussttoomm--rroouunndd==224488 is only generated if --ffnnoo--mmaatthh--eerrrrnnoo is speci- fied. In contrast to the other configurations, --ffssiinnggllee--pprreeccii-- ssiioonn--ccoonnssttaanntt is not set. These additional --mm options are available for the Altera Nios II ELF (bare-metal) target: --mmhhaall Link with HAL BSP. This suppresses linking with the GCC-provided C runtime startup and termination code, and is typically used in con- junction with --mmssyyss--ccrrtt00== to specify the location of the alternate startup code provided by the HAL BSP. --mmssmmaallllcc Link with a limited version of the C library, --llssmmaallllcc, rather than Newlib. --mmssyyss--ccrrtt00==_s_t_a_r_t_f_i_l_e _s_t_a_r_t_f_i_l_e is the file name of the startfile (crt0) to use when linking. This option is only useful in conjunction with --mmhhaall. --mmssyyss--lliibb==_s_y_s_t_e_m_l_i_b _s_y_s_t_e_m_l_i_b is the library name of the library that provides low- level system calls required by the C library, e.g. "read" and "write". This option is typically used to link with a library pro- vided by a HAL BSP. _N_v_i_d_i_a _P_T_X _O_p_t_i_o_n_s These options are defined for Nvidia PTX: --mm6644 Ignored, but preserved for backward compatibility. Only 64-bit ABI is supported. --mmaarrcchh==_a_r_c_h_i_t_e_c_t_u_r_e_-_s_t_r_i_n_g Generate code for the specified PTX ISA target architecture (e.g. ssmm__3355). Valid architecture strings are ssmm__3300, ssmm__3355, ssmm__5533, ssmm__7700, ssmm__7755 and ssmm__8800. The default target architecture is sm_30. This option sets the value of the preprocessor macro "__PTX_SM__"; for instance, for ssmm__3355, it has the value 335500. --mmiissaa==_a_r_c_h_i_t_e_c_t_u_r_e_-_s_t_r_i_n_g Alias of --mmaarrcchh==. --mmaarrcchh--mmaapp==_a_r_c_h_i_t_e_c_t_u_r_e_-_s_t_r_i_n_g Select the closest available --mmaarrcchh== value that is not more capa- ble. For instance, for --mmaarrcchh--mmaapp==ssmm__5500 select --mmaarrcchh==ssmm__3355, and for --mmaarrcchh--mmaapp==ssmm__5533 select --mmaarrcchh==ssmm__5533. --mmppttxx==_v_e_r_s_i_o_n_-_s_t_r_i_n_g Generate code for the specified PTX ISA version (e.g. 77..00). Valid version strings include 33..11, 66..00, 66..33, and 77..00. The default PTX ISA version is 6.0, unless a higher version is required for speci- fied PTX ISA target architecture via option --mmaarrcchh==. This option sets the values of the preprocessor macros "__PTX_ISA_VERSION_MAJOR__" and "__PTX_ISA_VERSION_MINOR__"; for instance, for 33..11 the macros have the values 33 and 11, respectively. --mmmmaaiinnkkeerrnneell Link in code for a __main kernel. This is for stand-alone instead of offloading execution. --mmooppttiimmiizzee Apply partitioned execution optimizations. This is the default when any level of optimization is selected. --mmssoofftt--ssttaacckk Generate code that does not use ".local" memory directly for stack storage. Instead, a per-warp stack pointer is maintained explic- itly. This enables variable-length stack allocation (with variable- length arrays or "alloca"), and when global memory is used for un- derlying storage, makes it possible to access automatic variables from other threads, or with atomic instructions. This code genera- tion variant is used for OpenMP offloading, but the option is ex- posed on its own for the purpose of testing the compiler; to gener- ate code suitable for linking into programs using OpenMP offload- ing, use option --mmggoommpp. --mmuunniiffoorrmm--ssiimmtt Switch to code generation variant that allows to execute all threads in each warp, while maintaining memory state and side ef- fects as if only one thread in each warp was active outside of OpenMP SIMD regions. All atomic operations and calls to runtime (malloc, free, vprintf) are conditionally executed (iff current lane index equals the master lane index), and the register being assigned is copied via a shuffle instruction from the master lane. Outside of SIMD regions lane 0 is the master; inside, each thread sees itself as the master. Shared memory array "int __nvptx_uni[]" stores all-zeros or all-ones bitmasks for each warp, indicating current mode (0 outside of SIMD regions). Each thread can bitwise- and the bitmask at position "tid.y" with current lane index to com- pute the master lane index. --mmggoommpp Generate code for use in OpenMP offloading: enables --mmssoofftt--ssttaacckk and --mmuunniiffoorrmm--ssiimmtt options, and selects corresponding multilib variant. _O_p_e_n_R_I_S_C _O_p_t_i_o_n_s These options are defined for OpenRISC: --mmbbooaarrdd==_n_a_m_e Configure a board specific runtime. This will be passed to the linker for newlib board library linking. The default is "or1ksim". --mmnneewwlliibb This option is ignored; it is for compatibility purposes only. This used to select linker and preprocessor options for use with newlib. --mmssoofftt--ddiivv --mmhhaarrdd--ddiivv Select software or hardware divide ("l.div", "l.divu") instruc- tions. This default is hardware divide. --mmssoofftt--mmuull --mmhhaarrdd--mmuull Select software or hardware multiply ("l.mul", "l.muli") instruc- tions. This default is hardware multiply. --mmssoofftt--ffllooaatt --mmhhaarrdd--ffllooaatt Select software or hardware for floating point operations. The de- fault is software. --mmddoouubbllee--ffllooaatt When --mmhhaarrdd--ffllooaatt is selected, enables generation of double-preci- sion floating point instructions. By default functions from _l_i_b_g_c_c are used to perform double-precision floating point operations. --mmuunnoorrddeerreedd--ffllooaatt When --mmhhaarrdd--ffllooaatt is selected, enables generation of unordered floating point compare and set flag ("lf.sfun*") instructions. By default functions from _l_i_b_g_c_c are used to perform unordered float- ing point compare and set flag operations. --mmccmmoovv Enable generation of conditional move ("l.cmov") instructions. By default the equivalent will be generated using set and branch. --mmrroorr Enable generation of rotate right ("l.ror") instructions. By de- fault functions from _l_i_b_g_c_c are used to perform rotate right opera- tions. --mmrroorrii Enable generation of rotate right with immediate ("l.rori") in- structions. By default functions from _l_i_b_g_c_c are used to perform rotate right with immediate operations. --mmsseexxtt Enable generation of sign extension ("l.ext*") instructions. By default memory loads are used to perform sign extension. --mmssffiimmmm Enable generation of compare and set flag with immediate ("l.sf*i") instructions. By default extra instructions will be generated to store the immediate to a register first. --mmsshhffttiimmmm Enable generation of shift with immediate ("l.srai", "l.srli", "l.slli") instructions. By default extra instructions will be gen- erated to store the immediate to a register first. --mmccmmooddeell==ssmmaallll Generate OpenRISC code for the small model: The GOT is limited to 64k. This is the default model. --mmccmmooddeell==llaarrggee Generate OpenRISC code for the large model: The GOT may grow up to 4G in size. _P_D_P_-_1_1 _O_p_t_i_o_n_s These options are defined for the PDP-11: --mmffppuu Use hardware FPP floating point. This is the default. (FIS float- ing point on the PDP-11/40 is not supported.) Implies -m45. --mmssoofftt--ffllooaatt Do not use hardware floating point. --mmaacc00 Return floating-point results in ac0 (fr0 in Unix assembler syn- tax). --mmnnoo--aacc00 Return floating-point results in memory. This is the default. --mm4400 Generate code for a PDP-11/40. Implies -msoft-float -mno-split. --mm4455 Generate code for a PDP-11/45. This is the default. --mm1100 Generate code for a PDP-11/10. Implies -msoft-float -mno-split. --mmiinntt1166 --mmnnoo--iinntt3322 Use 16-bit "int". This is the default. --mmiinntt3322 --mmnnoo--iinntt1166 Use 32-bit "int". --mmsspplliitt Target has split instruction and data space. Implies -m45. --mmuunniixx--aassmm Use Unix assembler syntax. --mmddeecc--aassmm Use DEC assembler syntax. --mmggnnuu--aassmm Use GNU assembler syntax. This is the default. --mmllrraa Use the new LRA register allocator. By default, the old "reload" allocator is used. _p_i_c_o_C_h_i_p _O_p_t_i_o_n_s These --mm options are defined for picoChip implementations: --mmaaee==_a_e___t_y_p_e Set the instruction set, register set, and instruction scheduling parameters for array element type _a_e___t_y_p_e. Supported values for _a_e___t_y_p_e are AANNYY, MMUULL, and MMAACC. --mmaaee==AANNYY selects a completely generic AE type. Code generated with this option runs on any of the other AE types. The code is not as efficient as it would be if compiled for a specific AE type, and some types of operation (e.g., multiplication) do not work properly on all types of AE. --mmaaee==MMUULL selects a MUL AE type. This is the most useful AE type for compiled code, and is the default. --mmaaee==MMAACC selects a DSP-style MAC AE. Code compiled with this op- tion may suffer from poor performance of byte (char) manipulation, since the DSP AE does not provide hardware support for byte load/stores. --mmssyymmbbooll--aass--aaddddrreessss Enable the compiler to directly use a symbol name as an address in a load/store instruction, without first loading it into a register. Typically, the use of this option generates larger programs, which run faster than when the option isn't used. However, the results vary from program to program, so it is left as a user option, rather than being permanently enabled. --mmnnoo--iinneeffffiicciieenntt--wwaarrnniinnggss Disables warnings about the generation of inefficient code. These warnings can be generated, for example, when compiling code that performs byte-level memory operations on the MAC AE type. The MAC AE has no hardware support for byte-level memory operations, so all byte load/stores must be synthesized from word load/store opera- tions. This is inefficient and a warning is generated to indicate that you should rewrite the code to avoid byte operations, or to target an AE type that has the necessary hardware support. This option disables these warnings. _P_o_w_e_r_P_C _O_p_t_i_o_n_s These are listed under _P_R_U _O_p_t_i_o_n_s These command-line options are defined for PRU target: --mmiinnrrtt Link with a minimum runtime environment, with no support for static initializers and constructors. Using this option can significantly reduce the size of the final ELF binary. Beware that the compiler could still generate code with static initializers and construc- tors. It is up to the programmer to ensure that the source program will not use those features. --mmmmccuu==_m_c_u Specify the PRU MCU variant to use. Check Newlib for the exact list of supported MCUs. --mmnnoo--rreellaaxx Make GCC pass the ----nnoo--rreellaaxx command-line option to the linker in- stead of the ----rreellaaxx option. --mmlloooopp Allow (or do not allow) GCC to use the LOOP instruction. --mmaabbii==_v_a_r_i_a_n_t Specify the ABI variant to output code for. --mmaabbii==ttii selects the unmodified TI ABI while --mmaabbii==ggnnuu selects a GNU variant that copes more naturally with certain GCC assumptions. These are the differ- ences: FFuunnccttiioonn PPooiinntteerr SSiizzee TI ABI specifies that function (code) pointers are 16-bit, whereas GNU supports only 32-bit data and code pointers. OOppttiioonnaall RReettuurrnn VVaalluuee PPooiinntteerr Function return values larger than 64 bits are passed by using a hidden pointer as the first argument of the function. TI ABI, though, mandates that the pointer can be NULL in case the caller is not using the returned value. GNU always passes and expects a valid return value pointer. The current --mmaabbii==ttii implementation simply raises a compile error when any of the above code constructs is detected. As a conse- quence the standard C library cannot be built and it is omitted when linking with --mmaabbii==ttii. Relaxation is a GNU feature and for safety reasons is disabled when using --mmaabbii==ttii. The TI toolchain does not emit relocations for QBBx instructions, so the GNU linker cannot adjust them when short- ening adjacent LDI32 pseudo instructions. _R_I_S_C_-_V _O_p_t_i_o_n_s These command-line options are defined for RISC-V targets: --mmbbrraanncchh--ccoosstt==_n Set the cost of branches to roughly _n instructions. --mmpplltt --mmnnoo--pplltt When generating PIC code, do or don't allow the use of PLTs. Ig- nored for non-PIC. The default is --mmpplltt. --mmaabbii==_A_B_I_-_s_t_r_i_n_g Specify integer and floating-point calling convention. _A_B_I_-_s_t_r_i_n_g contains two parts: the size of integer types and the registers used for floating-point types. For example --mmaarrcchh==rrvv6644iiffdd --mmaabbii==llpp6644dd means that lloonngg and pointers are 64-bit (implicitly defining iinntt to be 32-bit), and that floating-point values up to 64 bits wide are passed in F registers. Contrast this with --mmaarrcchh==rrvv6644iiffdd --mmaabbii==llpp6644ff, which still allows the compiler to gen- erate code that uses the F and D extensions but only allows float- ing-point values up to 32 bits long to be passed in registers; or --mmaarrcchh==rrvv6644iiffdd --mmaabbii==llpp6644, in which no floating-point arguments will be passed in registers. The default for this argument is system dependent, users who want a specific calling convention should specify one explicitly. The valid calling conventions are: iillpp3322, iillpp3322ff, iillpp3322dd, llpp6644, llpp6644ff, and llpp6644dd. Some calling conventions are impossible to implement on some ISAs: for example, --mmaarrcchh==rrvv3322iiff --mmaabbii==iillpp3322dd is invalid be- cause the ABI requires 64-bit values be passed in F registers, but F registers are only 32 bits wide. There is also the iillpp3322ee ABI that can only be used with the rrvv3322ee architecture. This ABI is not well specified at present, and is subject to change. --mmffddiivv --mmnnoo--ffddiivv Do or don't use hardware floating-point divide and square root in- structions. This requires the F or D extensions for floating-point registers. The default is to use them if the specified architec- ture has these instructions. --mmddiivv --mmnnoo--ddiivv Do or don't use hardware instructions for integer division. This requires the M extension. The default is to use them if the speci- fied architecture has these instructions. --mmiissaa--ssppeecc==_I_S_A_-_s_p_e_c_-_s_t_r_i_n_g Specify the version of the RISC-V Unprivileged (formerly User-Level) ISA specification to produce code conforming to. The possibilities for _I_S_A_-_s_p_e_c_-_s_t_r_i_n_g are: 2.2 Produce code conforming to version 2.2. 20190608 Produce code conforming to version 20190608. 20191213 Produce code conforming to version 20191213. The default is --mmiissaa--ssppeecc==2200119911221133 unless GCC has been configured with ----wwiitthh--iissaa--ssppeecc== specifying a different default version. --mmaarrcchh==_I_S_A_-_s_t_r_i_n_g Generate code for given RISC-V ISA (e.g. rrvv6644iimm). ISA strings must be lower-case. Examples include rrvv6644ii, rrvv3322gg, rrvv3322ee, and rrvv3322iimmaaff. When --mmaarrcchh== is not specified, use the setting from --mmccppuu. If both --mmaarrcchh and --mmccppuu== are not specified, the default for this argument is system dependent, users who want a specific architec- ture extensions should specify one explicitly. --mmccppuu==_p_r_o_c_e_s_s_o_r_-_s_t_r_i_n_g Use architecture of and optimize the output for the given proces- sor, specified by particular CPU name. Permissible values for this option are: ssiiffiivvee--ee2200, ssiiffiivvee--ee2211, ssiiffiivvee--ee2244, ssiiffiivvee--ee3311, ssiiffiivvee--ee3344, ssiiffiivvee--ee7766, ssiiffiivvee--ss2211, ssiiffiivvee--ss5511, ssiiffiivvee--ss5544, ssiiffiivvee--ss7766, ssiiffiivvee--uu5544, and ssiiffiivvee--uu7744. --mmttuunnee==_p_r_o_c_e_s_s_o_r_-_s_t_r_i_n_g Optimize the output for the given processor, specified by microar- chitecture or particular CPU name. Permissible values for this op- tion are: rroocckkeett, ssiiffiivvee--33--sseerriieess, ssiiffiivvee--55--sseerriieess, ssiiffiivvee--77--ssee-- rriieess, ssiizzee, and all valid options for --mmccppuu==. When --mmttuunnee== is not specified, use the setting from --mmccppuu, the de- fault is rroocckkeett if both are not specified. The ssiizzee choice is not intended for use by end-users. This is used when --OOss is specified. It overrides the instruction cost info pro- vided by --mmttuunnee==, but does not override the pipeline info. This helps reduce code size while still giving good performance. --mmpprreeffeerrrreedd--ssttaacckk--bboouunnddaarryy==_n_u_m Attempt to keep the stack boundary aligned to a 2 raised to _n_u_m byte boundary. If --mmpprreeffeerrrreedd--ssttaacckk--bboouunnddaarryy is not specified, the default is 4 (16 bytes or 128-bits). WWaarrnniinngg:: If you use this switch, then you must build all modules with the same value, including any libraries. This includes the system libraries and startup modules. --mmssmmaallll--ddaattaa--lliimmiitt==_n Put global and static data smaller than _n bytes into a special sec- tion (on some targets). --mmssaavvee--rreessttoorree --mmnnoo--ssaavvee--rreessttoorree Do or don't use smaller but slower prologue and epilogue code that uses library function calls. The default is to use fast inline prologues and epilogues. --mmsshhoorrtteenn--mmeemmrreeffss --mmnnoo--sshhoorrtteenn--mmeemmrreeffss Do or do not attempt to make more use of compressed load/store in- structions by replacing a load/store of 'base register + large off- set' with a new load/store of 'new base + small offset'. If the new base gets stored in a compressed register, then the new load/store can be compressed. Currently targets 32-bit integer load/stores only. --mmssttrriicctt--aalliiggnn --mmnnoo--ssttrriicctt--aalliiggnn Do not or do generate unaligned memory accesses. The default is set depending on whether the processor we are optimizing for sup- ports fast unaligned access or not. --mmccmmooddeell==mmeeddllooww Generate code for the medium-low code model. The program and its statically defined symbols must lie within a single 2 GiB address range and must lie between absolute addresses -2 GiB and +2 GiB. Programs can be statically or dynamically linked. This is the de- fault code model. --mmccmmooddeell==mmeeddaannyy Generate code for the medium-any code model. The program and its statically defined symbols must be within any single 2 GiB address range. Programs can be statically or dynamically linked. The code generated by the medium-any code model is position-inde- pendent, but is not guaranteed to function correctly when linked into position-independent executables or libraries. --mmeexxpplliicciitt--rreellooccss --mmnnoo--eexxlliicciitt--rreellooccss Use or do not use assembler relocation operators when dealing with symbolic addresses. The alternative is to use assembler macros in- stead, which may limit optimization. --mmrreellaaxx --mmnnoo--rreellaaxx Take advantage of linker relaxations to reduce the number of in- structions required to materialize symbol addresses. The default is to take advantage of linker relaxations. --mmeemmiitt--aattttrriibbuuttee --mmnnoo--eemmiitt--aattttrriibbuuttee Emit (do not emit) RISC-V attribute to record extra information into ELF objects. This feature requires at least binutils 2.32. --mmaalliiggnn--ddaattaa==_t_y_p_e Control how GCC aligns variables and constants of array, structure, or union types. Supported values for _t_y_p_e are xxlleenn which uses x register width as the alignment value, and nnaattuurraall which uses natu- ral alignment. xxlleenn is the default. --mmbbiigg--eennddiiaann Generate big-endian code. This is the default when GCC is config- ured for a rriissccvv6644bbee--**--** or rriissccvv3322bbee--**--** target. --mmlliittttllee--eennddiiaann Generate little-endian code. This is the default when GCC is con- figured for a rriissccvv6644--**--** or rriissccvv3322--**--** but not a rriissccvv6644bbee--**--** or rriissccvv3322bbee--**--** target. --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd==_g_u_a_r_d --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--rreegg==_r_e_g --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ooffffsseett==_o_f_f_s_e_t Generate stack protection code using canary at _g_u_a_r_d. Supported locations are gglloobbaall for a global canary or ttllss for per-thread ca- nary in the TLS block. With the latter choice the options --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--rreegg==_r_e_g and --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ooffffsseett==_o_f_f_s_e_t furthermore specify which register to use as base register for reading the canary, and from what offset from that base register. There is no default register or offset as this is entirely for use within the Linux kernel. _R_L_7_8 _O_p_t_i_o_n_s --mmssiimm Links in additional target libraries to support operation within a simulator. --mmmmuull==nnoonnee --mmmmuull==gg1100 --mmmmuull==gg1133 --mmmmuull==gg1144 --mmmmuull==rrll7788 Specifies the type of hardware multiplication and division support to be used. The simplest is "none", which uses software for both multiplication and division. This is the default. The "g13" value is for the hardware multiply/divide peripheral found on the RL78/G13 (S2 core) targets. The "g14" value selects the use of the multiplication and division instructions supported by the RL78/G14 (S3 core) parts. The value "rl78" is an alias for "g14" and the value "mg10" is an alias for "none". In addition a C preprocessor macro is defined, based upon the set- ting of this option. Possible values are: "__RL78_MUL_NONE__", "__RL78_MUL_G13__" or "__RL78_MUL_G14__". --mmccppuu==gg1100 --mmccppuu==gg1133 --mmccppuu==gg1144 --mmccppuu==rrll7788 Specifies the RL78 core to target. The default is the G14 core, also known as an S3 core or just RL78. The G13 or S2 core does not have multiply or divide instructions, instead it uses a hardware peripheral for these operations. The G10 or S1 core does not have register banks, so it uses a different calling convention. If this option is set it also selects the type of hardware multiply support to use, unless this is overridden by an explicit --mmmmuull==nnoonnee option on the command line. Thus specifying --mmccppuu==gg1133 enables the use of the G13 hardware multiply peripheral and specifying --mmccppuu==gg1100 disables the use of hardware multiplications altogether. Note, although the RL78/G14 core is the default target, specifying --mmccppuu==gg1144 or --mmccppuu==rrll7788 on the command line does change the behav- ior of the toolchain since it also enables G14 hardware multiply support. If these options are not specified on the command line then software multiplication routines will be used even though the code targets the RL78 core. This is for backwards compatibility with older toolchains which did not have hardware multiply and di- vide support. In addition a C preprocessor macro is defined, based upon the set- ting of this option. Possible values are: "__RL78_G10__", "__RL78_G13__" or "__RL78_G14__". --mmgg1100 --mmgg1133 --mmgg1144 --mmrrll7788 These are aliases for the corresponding --mmccppuu== option. They are provided for backwards compatibility. --mmaallllrreeggss Allow the compiler to use all of the available registers. By de- fault registers "r24..r31" are reserved for use in interrupt han- dlers. With this option enabled these registers can be used in or- dinary functions as well. --mm6644bbiitt--ddoouubblleess --mm3322bbiitt--ddoouubblleess Make the "double" data type be 64 bits (--mm6644bbiitt--ddoouubblleess) or 32 bits (--mm3322bbiitt--ddoouubblleess) in size. The default is --mm3322bbiitt--ddoouubblleess. --mmssaavvee--mmdduucc--iinn--iinntteerrrruuppttss --mmnnoo--ssaavvee--mmdduucc--iinn--iinntteerrrruuppttss Specifies that interrupt handler functions should preserve the MDUC registers. This is only necessary if normal code might use the MDUC registers, for example because it performs multiplication and division operations. The default is to ignore the MDUC registers as this makes the interrupt handlers faster. The target option -mg13 needs to be passed for this to work as this feature is only available on the G13 target (S2 core). The MDUC registers will only be saved if the interrupt handler performs a multiplication or division operation or it calls another function. _I_B_M _R_S_/_6_0_0_0 _a_n_d _P_o_w_e_r_P_C _O_p_t_i_o_n_s These --mm options are defined for the IBM RS/6000 and PowerPC: --mmppoowweerrppcc--ggppoopptt --mmnnoo--ppoowweerrppcc--ggppoopptt --mmppoowweerrppcc--ggffxxoopptt --mmnnoo--ppoowweerrppcc--ggffxxoopptt --mmppoowweerrppcc6644 --mmnnoo--ppoowweerrppcc6644 --mmmmffccrrff --mmnnoo--mmffccrrff --mmppooppccnnttbb --mmnnoo--ppooppccnnttbb --mmppooppccnnttdd --mmnnoo--ppooppccnnttdd --mmffpprrnndd --mmnnoo--ffpprrnndd --mmccmmppbb --mmnnoo--ccmmppbb --mmhhaarrdd--ddffpp --mmnnoo--hhaarrdd--ddffpp You use these options to specify which instructions are available on the processor you are using. The default value of these options is determined when configuring GCC. Specifying the --mmccppuu==_c_p_u___t_y_p_e overrides the specification of these options. We recommend you use the --mmccppuu==_c_p_u___t_y_p_e option rather than the options listed above. Specifying --mmppoowweerrppcc--ggppoopptt allows GCC to use the optional PowerPC architecture instructions in the General Purpose group, including floating-point square root. Specifying --mmppoowweerrppcc--ggffxxoopptt allows GCC to use the optional PowerPC architecture instructions in the Graph- ics group, including floating-point select. The --mmmmffccrrff option allows GCC to generate the move from condition register field instruction implemented on the POWER4 processor and other processors that support the PowerPC V2.01 architecture. The --mmppooppccnnttbb option allows GCC to generate the popcount and double- precision FP reciprocal estimate instruction implemented on the POWER5 processor and other processors that support the PowerPC V2.02 architecture. The --mmppooppccnnttdd option allows GCC to generate the popcount instruction implemented on the POWER7 processor and other processors that support the PowerPC V2.06 architecture. The --mmffpprrnndd option allows GCC to generate the FP round to integer in- structions implemented on the POWER5+ processor and other proces- sors that support the PowerPC V2.03 architecture. The --mmccmmppbb op- tion allows GCC to generate the compare bytes instruction imple- mented on the POWER6 processor and other processors that support the PowerPC V2.05 architecture. The --mmhhaarrdd--ddffpp option allows GCC to generate the decimal floating-point instructions implemented on some POWER processors. The --mmppoowweerrppcc6644 option allows GCC to generate the additional 64-bit instructions that are found in the full PowerPC64 architecture and to treat GPRs as 64-bit, doubleword quantities. GCC defaults to --mmnnoo--ppoowweerrppcc6644. --mmccppuu==_c_p_u___t_y_p_e Set architecture type, register usage, and instruction scheduling parameters for machine type _c_p_u___t_y_p_e. Supported values for _c_p_u___t_y_p_e are 440011, 440033, 440055, 440055ffpp, 444400, 444400ffpp, 446644, 446644ffpp, 447766, 447766ffpp, 550055, 660011, 660022, 660033, 660033ee, 660044, 660044ee, 662200, 663300, 774400, 77440000, 77445500, 775500, 880011, 882211, 882233, 886600, 997700, 88554400, aa22, ee330000cc22, ee330000cc33, ee550000mmcc, ee550000mmcc6644, ee55550000, ee66550000, eecc660033ee, GG33, GG44, GG55, ttiittaann, ppoowweerr33, ppoowweerr44, ppoowweerr55, ppoowweerr55++, ppoowweerr66, ppoowweerr66xx, ppoowweerr77, ppoowweerr88, ppoowweerr99, ppoowweerr1100, ppoowweerrppcc, ppoowweerrppcc6644, ppoowweerrppcc6644llee, rrss6644, and nnaattiivvee. --mmccppuu==ppoowweerrppcc, --mmccppuu==ppoowweerrppcc6644, and --mmccppuu==ppoowweerrppcc6644llee specify pure 32-bit PowerPC (either endian), 64-bit big endian PowerPC and 64-bit little endian PowerPC architecture machine types, with an appropriate, generic processor model assumed for scheduling pur- poses. Specifying nnaattiivvee as cpu type detects and selects the architecture option that corresponds to the host processor of the system per- forming the compilation. --mmccppuu==nnaattiivvee has no effect if GCC does not recognize the processor. The other options specify a specific processor. Code generated un- der those options runs best on that processor, and may not run at all on others. The --mmccppuu options automatically enable or disable the following op- tions: --mmaallttiivveecc --mmffpprrnndd --mmhhaarrdd--ffllooaatt --mmmmffccrrff --mmmmuullttiippllee --mmppooppccnnttbb --mmppooppccnnttdd --mmppoowweerrppcc6644 --mmppoowweerrppcc--ggppoopptt --mmppoowweerrppcc--ggffxxoopptt --mmmmuullhhww --mmddllmmzzbb --mmmmffppggpprr --mmvvssxx --mmccrryyppttoo --mmhhttmm --mmppoowweerr88--ffuussiioonn --mmppoowweerr88--vveeccttoorr --mmqquuaadd--mmeemmoorryy --mmqquuaadd--mmeemmoorryy--aattoommiicc --mmffllooaatt112288 --mmffllooaatt112288--hhaarrddwwaarree --mmpprreeffiixxeedd --mmppccrreell --mmmmmmaa --mmrroopp--pprrootteecctt The particular options set for any particular CPU varies between compiler versions, depending on what setting seems to produce opti- mal code for that CPU; it doesn't necessarily reflect the actual hardware's capabilities. If you wish to set an individual option to a particular value, you may specify it after the --mmccppuu option, like --mmccppuu==997700 --mmnnoo--aallttiivveecc. On AIX, the --mmaallttiivveecc and --mmppoowweerrppcc6644 options are not enabled or disabled by the --mmccppuu option at present because AIX does not have full support for these options. You may still enable or disable them individually if you're sure it'll work in your environment. --mmttuunnee==_c_p_u___t_y_p_e Set the instruction scheduling parameters for machine type _c_p_u___t_y_p_e, but do not set the architecture type or register usage, as --mmccppuu==_c_p_u___t_y_p_e does. The same values for _c_p_u___t_y_p_e are used for --mmttuunnee as for --mmccppuu. If both are specified, the code generated uses the architecture and registers set by --mmccppuu, but the schedul- ing parameters set by --mmttuunnee. --mmccmmooddeell==ssmmaallll Generate PowerPC64 code for the small model: The TOC is limited to 64k. --mmccmmooddeell==mmeeddiiuumm Generate PowerPC64 code for the medium model: The TOC and other static data may be up to a total of 4G in size. This is the de- fault for 64-bit Linux. --mmccmmooddeell==llaarrggee Generate PowerPC64 code for the large model: The TOC may be up to 4G in size. Other data and code is only limited by the 64-bit ad- dress space. --mmaallttiivveecc --mmnnoo--aallttiivveecc Generate code that uses (does not use) AltiVec instructions, and also enable the use of built-in functions that allow more direct access to the AltiVec instruction set. You may also need to set --mmaabbii==aallttiivveecc to adjust the current ABI with AltiVec ABI enhance- ments. When --mmaallttiivveecc is used, the element order for AltiVec intrinsics such as "vec_splat", "vec_extract", and "vec_insert" match array element order corresponding to the endianness of the target. That is, element zero identifies the leftmost element in a vector regis- ter when targeting a big-endian platform, and identifies the right- most element in a vector register when targeting a little-endian platform. --mmvvrrssaavvee --mmnnoo--vvrrssaavvee Generate VRSAVE instructions when generating AltiVec code. --mmsseeccuurree--pplltt Generate code that allows lldd and lldd..ssoo to build executables and shared libraries with non-executable ".plt" and ".got" sections. This is a PowerPC 32-bit SYSV ABI option. --mmbbssss--pplltt Generate code that uses a BSS ".plt" section that lldd..ssoo fills in, and requires ".plt" and ".got" sections that are both writable and executable. This is a PowerPC 32-bit SYSV ABI option. --mmiisseell --mmnnoo--iisseell This switch enables or disables the generation of ISEL instruc- tions. --mmvvssxx --mmnnoo--vvssxx Generate code that uses (does not use) vector/scalar (VSX) instruc- tions, and also enable the use of built-in functions that allow more direct access to the VSX instruction set. --mmccrryyppttoo --mmnnoo--ccrryyppttoo Enable the use (disable) of the built-in functions that allow di- rect access to the cryptographic instructions that were added in version 2.07 of the PowerPC ISA. --mmhhttmm --mmnnoo--hhttmm Enable (disable) the use of the built-in functions that allow di- rect access to the Hardware Transactional Memory (HTM) instructions that were added in version 2.07 of the PowerPC ISA. --mmppoowweerr88--ffuussiioonn --mmnnoo--ppoowweerr88--ffuussiioonn Generate code that keeps (does not keeps) some integer operations adjacent so that the instructions can be fused together on power8 and later processors. --mmppoowweerr88--vveeccttoorr --mmnnoo--ppoowweerr88--vveeccttoorr Generate code that uses (does not use) the vector and scalar in- structions that were added in version 2.07 of the PowerPC ISA. Also enable the use of built-in functions that allow more direct access to the vector instructions. --mmqquuaadd--mmeemmoorryy --mmnnoo--qquuaadd--mmeemmoorryy Generate code that uses (does not use) the non-atomic quad word memory instructions. The --mmqquuaadd--mmeemmoorryy option requires use of 64-bit mode. --mmqquuaadd--mmeemmoorryy--aattoommiicc --mmnnoo--qquuaadd--mmeemmoorryy--aattoommiicc Generate code that uses (does not use) the atomic quad word memory instructions. The --mmqquuaadd--mmeemmoorryy--aattoommiicc option requires use of 64-bit mode. --mmffllooaatt112288 --mmnnoo--ffllooaatt112288 Enable/disable the _____f_l_o_a_t_1_2_8 keyword for IEEE 128-bit floating point and use either software emulation for IEEE 128-bit floating point or hardware instructions. The VSX instruction set (--mmvvssxx) must be enabled to use the IEEE 128-bit floating point support. The IEEE 128-bit floating point is only supported on Linux. The default for --mmffllooaatt112288 is enabled on PowerPC Linux systems us- ing the VSX instruction set, and disabled on other systems. If you use the ISA 3.0 instruction set (--mmppoowweerr99--vveeccttoorr or --mmccppuu==ppoowweerr99) on a 64-bit system, the IEEE 128-bit floating point support will also enable the generation of ISA 3.0 IEEE 128-bit floating point instructions. Otherwise, if you do not specify to generate ISA 3.0 instructions or you are targeting a 32-bit big en- dian system, IEEE 128-bit floating point will be done with software emulation. --mmffllooaatt112288--hhaarrddwwaarree --mmnnoo--ffllooaatt112288--hhaarrddwwaarree Enable/disable using ISA 3.0 hardware instructions to support the _____f_l_o_a_t_1_2_8 data type. The default for --mmffllooaatt112288--hhaarrddwwaarree is enabled on PowerPC Linux systems using the ISA 3.0 instruction set, and disabled on other systems. --mm3322 --mm6644 Generate code for 32-bit or 64-bit environments of Darwin and SVR4 targets (including GNU/Linux). The 32-bit environment sets int, long and pointer to 32 bits and generates code that runs on any PowerPC variant. The 64-bit environment sets int to 32 bits and long and pointer to 64 bits, and generates code for PowerPC64, as for --mmppoowweerrppcc6644. --mmffuullll--ttoocc --mmnnoo--ffpp--iinn--ttoocc --mmnnoo--ssuumm--iinn--ttoocc --mmmmiinniimmaall--ttoocc Modify generation of the TOC (Table Of Contents), which is created for every executable file. The --mmffuullll--ttoocc option is selected by default. In that case, GCC allocates at least one TOC entry for each unique non-automatic variable reference in your program. GCC also places floating-point constants in the TOC. However, only 16,384 entries are available in the TOC. If you receive a linker error message that saying you have over- flowed the available TOC space, you can reduce the amount of TOC space used with the --mmnnoo--ffpp--iinn--ttoocc and --mmnnoo--ssuumm--iinn--ttoocc options. --mmnnoo--ffpp--iinn--ttoocc prevents GCC from putting floating-point constants in the TOC and --mmnnoo--ssuumm--iinn--ttoocc forces GCC to generate code to cal- culate the sum of an address and a constant at run time instead of putting that sum into the TOC. You may specify one or both of these options. Each causes GCC to produce very slightly slower and larger code at the expense of conserving TOC space. If you still run out of space in the TOC even when you specify both of these options, specify --mmmmiinniimmaall--ttoocc instead. This option causes GCC to make only one TOC entry for every file. When you specify this option, GCC produces code that is slower and larger but which uses extremely little TOC space. You may wish to use this option only on files that contain less frequently-executed code. --mmaaiixx6644 --mmaaiixx3322 Enable 64-bit AIX ABI and calling convention: 64-bit pointers, 64-bit "long" type, and the infrastructure needed to support them. Specifying --mmaaiixx6644 implies --mmppoowweerrppcc6644, while --mmaaiixx3322 disables the 64-bit ABI and implies --mmnnoo--ppoowweerrppcc6644. GCC defaults to --mmaaiixx3322. --mmxxll--ccoommppaatt --mmnnoo--xxll--ccoommppaatt Produce code that conforms more closely to IBM XL compiler seman- tics when using AIX-compatible ABI. Pass floating-point arguments to prototyped functions beyond the register save area (RSA) on the stack in addition to argument FPRs. Do not assume that most sig- nificant double in 128-bit long double value is properly rounded when comparing values and converting to double. Use XL symbol names for long double support routines. The AIX calling convention was extended but not initially docu- mented to handle an obscure K&R C case of calling a function that takes the address of its arguments with fewer arguments than de- clared. IBM XL compilers access floating-point arguments that do not fit in the RSA from the stack when a subroutine is compiled without optimization. Because always storing floating-point argu- ments on the stack is inefficient and rarely needed, this option is not enabled by default and only is necessary when calling subrou- tines compiled by IBM XL compilers without optimization. --mmppee Support _I_B_M _R_S_/_6_0_0_0 _S_P _P_a_r_a_l_l_e_l _E_n_v_i_r_o_n_m_e_n_t (PE). Link an applica- tion written to use message passing with special startup code to enable the application to run. The system must have PE installed in the standard location (_/_u_s_r_/_l_p_p_/_p_p_e_._p_o_e_/), or the _s_p_e_c_s file must be overridden with the --ssppeeccss== option to specify the appropri- ate directory location. The Parallel Environment does not support threads, so the --mmppee option and the --pptthhrreeaadd option are incompati- ble. --mmaalliiggnn--nnaattuurraall --mmaalliiggnn--ppoowweerr On AIX, 32-bit Darwin, and 64-bit PowerPC GNU/Linux, the option --mmaalliiggnn--nnaattuurraall overrides the ABI-defined alignment of larger types, such as floating-point doubles, on their natural size-based boundary. The option --mmaalliiggnn--ppoowweerr instructs GCC to follow the ABI-specified alignment rules. GCC defaults to the standard align- ment defined in the ABI. On 64-bit Darwin, natural alignment is the default, and --mmaa-- lliiggnn--ppoowweerr is not supported. --mmssoofftt--ffllooaatt --mmhhaarrdd--ffllooaatt Generate code that does not use (uses) the floating-point register set. Software floating-point emulation is provided if you use the --mmssoofftt--ffllooaatt option, and pass the option to GCC when linking. --mmmmuullttiippllee --mmnnoo--mmuullttiippllee Generate code that uses (does not use) the load multiple word in- structions and the store multiple word instructions. These in- structions are generated by default on POWER systems, and not gen- erated on PowerPC systems. Do not use --mmmmuullttiippllee on little-endian PowerPC systems, since those instructions do not work when the pro- cessor is in little-endian mode. The exceptions are PPC740 and PPC750 which permit these instructions in little-endian mode. --mmuuppddaattee --mmnnoo--uuppddaattee Generate code that uses (does not use) the load or store instruc- tions that update the base register to the address of the calcu- lated memory location. These instructions are generated by de- fault. If you use --mmnnoo--uuppddaattee, there is a small window between the time that the stack pointer is updated and the address of the pre- vious frame is stored, which means code that walks the stack frame across interrupts or signals may get corrupted data. --mmaavvooiidd--iinnddeexxeedd--aaddddrreesssseess --mmnnoo--aavvooiidd--iinnddeexxeedd--aaddddrreesssseess Generate code that tries to avoid (not avoid) the use of indexed load or store instructions. These instructions can incur a perfor- mance penalty on Power6 processors in certain situations, such as when stepping through large arrays that cross a 16M boundary. This option is enabled by default when targeting Power6 and disabled otherwise. --mmffuusseedd--mmaadddd --mmnnoo--ffuusseedd--mmaadddd Generate code that uses (does not use) the floating-point multiply and accumulate instructions. These instructions are generated by default if hardware floating point is used. The machine-dependent --mmffuusseedd--mmaadddd option is now mapped to the machine-independent --ffffpp--ccoonnttrraacctt==ffaasstt option, and --mmnnoo--ffuusseedd--mmaadddd is mapped to --ffffpp--ccoonnttrraacctt==ooffff. --mmmmuullhhww --mmnnoo--mmuullhhww Generate code that uses (does not use) the half-word multiply and multiply-accumulate instructions on the IBM 405, 440, 464 and 476 processors. These instructions are generated by default when tar- geting those processors. --mmddllmmzzbb --mmnnoo--ddllmmzzbb Generate code that uses (does not use) the string-search ddllmmzzbb in- struction on the IBM 405, 440, 464 and 476 processors. This in- struction is generated by default when targeting those processors. --mmnnoo--bbiitt--aalliiggnn --mmbbiitt--aalliiggnn On System V.4 and embedded PowerPC systems do not (do) force struc- tures and unions that contain bit-fields to be aligned to the base type of the bit-field. For example, by default a structure containing nothing but 8 "un- signed" bit-fields of length 1 is aligned to a 4-byte boundary and has a size of 4 bytes. By using --mmnnoo--bbiitt--aalliiggnn, the structure is aligned to a 1-byte boundary and is 1 byte in size. --mmnnoo--ssttrriicctt--aalliiggnn --mmssttrriicctt--aalliiggnn On System V.4 and embedded PowerPC systems do not (do) assume that unaligned memory references are handled by the system. --mmrreellooccaattaabbllee --mmnnoo--rreellooccaattaabbllee Generate code that allows (does not allow) a static executable to be relocated to a different address at run time. A simple embedded PowerPC system loader should relocate the entire contents of ".got2" and 4-byte locations listed in the ".fixup" section, a ta- ble of 32-bit addresses generated by this option. For this to work, all objects linked together must be compiled with --mmrreellooccaatt-- aabbllee or --mmrreellooccaattaabbllee--lliibb. --mmrreellooccaattaabbllee code aligns the stack to an 8-byte boundary. --mmrreellooccaattaabbllee--lliibb --mmnnoo--rreellooccaattaabbllee--lliibb Like --mmrreellooccaattaabbllee, --mmrreellooccaattaabbllee--lliibb generates a ".fixup" section to allow static executables to be relocated at run time, but --mmrree-- llooccaattaabbllee--lliibb does not use the smaller stack alignment of --mmrreelloo-- ccaattaabbllee. Objects compiled with --mmrreellooccaattaabbllee--lliibb may be linked with objects compiled with any combination of the --mmrreellooccaattaabbllee op- tions. --mmnnoo--ttoocc --mmttoocc On System V.4 and embedded PowerPC systems do not (do) assume that register 2 contains a pointer to a global area pointing to the ad- dresses used in the program. --mmlliittttllee --mmlliittttllee--eennddiiaann On System V.4 and embedded PowerPC systems compile code for the processor in little-endian mode. The --mmlliittttllee--eennddiiaann option is the same as --mmlliittttllee. --mmbbiigg --mmbbiigg--eennddiiaann On System V.4 and embedded PowerPC systems compile code for the processor in big-endian mode. The --mmbbiigg--eennddiiaann option is the same as --mmbbiigg. --mmddyynnaammiicc--nnoo--ppiicc On Darwin and Mac OS X systems, compile code so that it is not re- locatable, but that its external references are relocatable. The resulting code is suitable for applications, but not shared li- braries. --mmssiinnggllee--ppiicc--bbaassee Treat the register used for PIC addressing as read-only, rather than loading it in the prologue for each function. The runtime system is responsible for initializing this register with an appro- priate value before execution begins. --mmpprriioorriittiizzee--rreessttrriicctteedd--iinnssnnss==_p_r_i_o_r_i_t_y This option controls the priority that is assigned to dispatch-slot restricted instructions during the second scheduling pass. The ar- gument _p_r_i_o_r_i_t_y takes the value 00, 11, or 22 to assign no, highest, or second-highest (respectively) priority to dispatch-slot re- stricted instructions. --mmsscchheedd--ccoossttllyy--ddeepp==_d_e_p_e_n_d_e_n_c_e___t_y_p_e This option controls which dependences are considered costly by the target during instruction scheduling. The argument _d_e_p_e_n_d_e_n_c_e___t_y_p_e takes one of the following values: nnoo No dependence is costly. aallll All dependences are costly. ttrruuee__ssttoorree__ttoo__llooaadd A true dependence from store to load is costly. ssttoorree__ttoo__llooaadd Any dependence from store to load is costly. _n_u_m_b_e_r Any dependence for which the latency is greater than or equal to _n_u_m_b_e_r is costly. --mmiinnsseerrtt--sscchheedd--nnooppss==_s_c_h_e_m_e This option controls which NOP insertion scheme is used during the second scheduling pass. The argument _s_c_h_e_m_e takes one of the fol- lowing values: nnoo Don't insert NOPs. ppaadd Pad with NOPs any dispatch group that has vacant issue slots, according to the scheduler's grouping. rreeggrroouupp__eexxaacctt Insert NOPs to force costly dependent insns into separate groups. Insert exactly as many NOPs as needed to force an insn to a new group, according to the estimated processor grouping. _n_u_m_b_e_r Insert NOPs to force costly dependent insns into separate groups. Insert _n_u_m_b_e_r NOPs to force an insn to a new group. --mmccaallll--ssyyssvv On System V.4 and embedded PowerPC systems compile code using call- ing conventions that adhere to the March 1995 draft of the System V Application Binary Interface, PowerPC processor supplement. This is the default unless you configured GCC using ppoowweerrppcc--**--eeaabbiiaaiixx. --mmccaallll--ssyyssvv--eeaabbii --mmccaallll--eeaabbii Specify both --mmccaallll--ssyyssvv and --mmeeaabbii options. --mmccaallll--ssyyssvv--nnooeeaabbii Specify both --mmccaallll--ssyyssvv and --mmnnoo--eeaabbii options. --mmccaallll--aaiixxddeesscc On System V.4 and embedded PowerPC systems compile code for the AIX operating system. --mmccaallll--lliinnuuxx On System V.4 and embedded PowerPC systems compile code for the Linux-based GNU system. --mmccaallll--ffrreeeebbssdd On System V.4 and embedded PowerPC systems compile code for the FreeBSD operating system. --mmccaallll--nneettbbssdd On System V.4 and embedded PowerPC systems compile code for the NetBSD operating system. --mmccaallll--ooppeennbbssdd On System V.4 and embedded PowerPC systems compile code for the OpenBSD operating system. --mmttrraacceebbaacckk==_t_r_a_c_e_b_a_c_k___t_y_p_e Select the type of traceback table. Valid values for _t_r_a_c_e_b_a_c_k___t_y_p_e are ffuullll, ppaarrtt, and nnoo. --mmaaiixx--ssttrruucctt--rreettuurrnn Return all structures in memory (as specified by the AIX ABI). --mmssvvrr44--ssttrruucctt--rreettuurrnn Return structures smaller than 8 bytes in registers (as specified by the SVR4 ABI). --mmaabbii==_a_b_i_-_t_y_p_e Extend the current ABI with a particular extension, or remove such extension. Valid values are: aallttiivveecc, nnoo--aallttiivveecc, iibbmmlloonnggddoouubbllee, iieeeeeelloonnggddoouubbllee, eellffvv11, eellffvv22, and for AIX: vveecc--eexxttaabbii, vveecc--ddeeffaauulltt. --mmaabbii==iibbmmlloonnggddoouubbllee Change the current ABI to use IBM extended-precision long double. This is not likely to work if your system defaults to using IEEE extended-precision long double. If you change the long double type from IEEE extended-precision, the compiler will issue a warning un- less you use the --WWnnoo--ppssaabbii option. Requires --mmlloonngg--ddoouubbllee--112288 to be enabled. --mmaabbii==iieeeeeelloonnggddoouubbllee Change the current ABI to use IEEE extended-precision long double. This is not likely to work if your system defaults to using IBM ex- tended-precision long double. If you change the long double type from IBM extended-precision, the compiler will issue a warning un- less you use the --WWnnoo--ppssaabbii option. Requires --mmlloonngg--ddoouubbllee--112288 to be enabled. --mmaabbii==eellffvv11 Change the current ABI to use the ELFv1 ABI. This is the default ABI for big-endian PowerPC 64-bit Linux. Overriding the default ABI requires special system support and is likely to fail in spec- tacular ways. --mmaabbii==eellffvv22 Change the current ABI to use the ELFv2 ABI. This is the default ABI for little-endian PowerPC 64-bit Linux. Overriding the default ABI requires special system support and is likely to fail in spec- tacular ways. --mmggnnuu--aattttrriibbuuttee --mmnnoo--ggnnuu--aattttrriibbuuttee Emit .gnu_attribute assembly directives to set tag/value pairs in a .gnu.attributes section that specify ABI variations in function pa- rameters or return values. --mmpprroottoottyyppee --mmnnoo--pprroottoottyyppee On System V.4 and embedded PowerPC systems assume that all calls to variable argument functions are properly prototyped. Otherwise, the compiler must insert an instruction before every non-prototyped call to set or clear bit 6 of the condition code register ("CR") to indicate whether floating-point values are passed in the floating- point registers in case the function takes variable arguments. With --mmpprroottoottyyppee, only calls to prototyped variable argument func- tions set or clear the bit. --mmssiimm On embedded PowerPC systems, assume that the startup module is called _s_i_m_-_c_r_t_0_._o and that the standard C libraries are _l_i_b_s_i_m_._a and _l_i_b_c_._a. This is the default for ppoowweerrppcc--**--eeaabbiissiimm configura- tions. --mmmmvvmmee On embedded PowerPC systems, assume that the startup module is called _c_r_t_0_._o and the standard C libraries are _l_i_b_m_v_m_e_._a and _l_i_b_c_._a. --mmaaddss On embedded PowerPC systems, assume that the startup module is called _c_r_t_0_._o and the standard C libraries are _l_i_b_a_d_s_._a and _l_i_b_c_._a. --mmyyeelllloowwkknniiffee On embedded PowerPC systems, assume that the startup module is called _c_r_t_0_._o and the standard C libraries are _l_i_b_y_k_._a and _l_i_b_c_._a. --mmvvxxwwoorrkkss On System V.4 and embedded PowerPC systems, specify that you are compiling for a VxWorks system. --mmeemmbb On embedded PowerPC systems, set the "PPC_EMB" bit in the ELF flags header to indicate that eeaabbii extended relocations are used. --mmeeaabbii --mmnnoo--eeaabbii On System V.4 and embedded PowerPC systems do (do not) adhere to the Embedded Applications Binary Interface (EABI), which is a set of modifications to the System V.4 specifications. Selecting --mmeeaabbii means that the stack is aligned to an 8-byte boundary, a function "__eabi" is called from "main" to set up the EABI environ- ment, and the --mmssddaattaa option can use both "r2" and "r13" to point to two separate small data areas. Selecting --mmnnoo--eeaabbii means that the stack is aligned to a 16-byte boundary, no EABI initialization function is called from "main", and the --mmssddaattaa option only uses "r13" to point to a single small data area. The --mmeeaabbii option is on by default if you configured GCC using one of the ppooww-- eerrppcc**--**--eeaabbii** options. --mmssddaattaa==eeaabbii On System V.4 and embedded PowerPC systems, put small initialized "const" global and static data in the ".sdata2" section, which is pointed to by register "r2". Put small initialized non-"const" global and static data in the ".sdata" section, which is pointed to by register "r13". Put small uninitialized global and static data in the ".sbss" section, which is adjacent to the ".sdata" section. The --mmssddaattaa==eeaabbii option is incompatible with the --mmrreellooccaattaabbllee op- tion. The --mmssddaattaa==eeaabbii option also sets the --mmeemmbb option. --mmssddaattaa==ssyyssvv On System V.4 and embedded PowerPC systems, put small global and static data in the ".sdata" section, which is pointed to by regis- ter "r13". Put small uninitialized global and static data in the ".sbss" section, which is adjacent to the ".sdata" section. The --mmssddaattaa==ssyyssvv option is incompatible with the --mmrreellooccaattaabbllee option. --mmssddaattaa==ddeeffaauulltt --mmssddaattaa On System V.4 and embedded PowerPC systems, if --mmeeaabbii is used, com- pile code the same as --mmssddaattaa==eeaabbii, otherwise compile code the same as --mmssddaattaa==ssyyssvv. --mmssddaattaa==ddaattaa On System V.4 and embedded PowerPC systems, put small global data in the ".sdata" section. Put small uninitialized global data in the ".sbss" section. Do not use register "r13" to address small data however. This is the default behavior unless other --mmssddaattaa options are used. --mmssddaattaa==nnoonnee --mmnnoo--ssddaattaa On embedded PowerPC systems, put all initialized global and static data in the ".data" section, and all uninitialized data in the ".bss" section. --mmrreeaaddoonnllyy--iinn--ssddaattaa Put read-only objects in the ".sdata" section as well. This is the default. --mmbblloocckk--mmoovvee--iinnlliinnee--lliimmiitt==_n_u_m Inline all block moves (such as calls to "memcpy" or structure copies) less than or equal to _n_u_m bytes. The minimum value for _n_u_m is 32 bytes on 32-bit targets and 64 bytes on 64-bit targets. The default value is target-specific. --mmbblloocckk--ccoommppaarree--iinnlliinnee--lliimmiitt==_n_u_m Generate non-looping inline code for all block compares (such as calls to "memcmp" or structure compares) less than or equal to _n_u_m bytes. If _n_u_m is 0, all inline expansion (non-loop and loop) of block compare is disabled. The default value is target-specific. --mmbblloocckk--ccoommppaarree--iinnlliinnee--lloooopp--lliimmiitt==_n_u_m Generate an inline expansion using loop code for all block compares that are less than or equal to _n_u_m bytes, but greater than the limit for non-loop inline block compare expansion. If the block length is not constant, at most _n_u_m bytes will be compared before "memcmp" is called to compare the remainder of the block. The de- fault value is target-specific. --mmssttrriinngg--ccoommppaarree--iinnlliinnee--lliimmiitt==_n_u_m Compare at most _n_u_m string bytes with inline code. If the differ- ence or end of string is not found at the end of the inline compare a call to "strcmp" or "strncmp" will take care of the rest of the comparison. The default is 64 bytes. --GG _n_u_m On embedded PowerPC systems, put global and static items less than or equal to _n_u_m bytes into the small data or BSS sections instead of the normal data or BSS section. By default, _n_u_m is 8. The --GG _n_u_m switch is also passed to the linker. All modules should be compiled with the same --GG _n_u_m value. --mmrreeggnnaammeess --mmnnoo--rreeggnnaammeess On System V.4 and embedded PowerPC systems do (do not) emit regis- ter names in the assembly language output using symbolic forms. --mmlloonnggccaallll --mmnnoo--lloonnggccaallll By default assume that all calls are far away so that a longer and more expensive calling sequence is required. This is required for calls farther than 32 megabytes (33,554,432 bytes) from the current location. A short call is generated if the compiler knows the call cannot be that far away. This setting can be overridden by the "shortcall" function attribute, or by "#pragma longcall(0)". Some linkers are capable of detecting out-of-range calls and gener- ating glue code on the fly. On these systems, long calls are un- necessary and generate slower code. As of this writing, the AIX linker can do this, as can the GNU linker for PowerPC/64. It is planned to add this feature to the GNU linker for 32-bit PowerPC systems as well. On PowerPC64 ELFv2 and 32-bit PowerPC systems with newer GNU link- ers, GCC can generate long calls using an inline PLT call sequence (see --mmppllttsseeqq). PowerPC with --mmbbssss--pplltt and PowerPC64 ELFv1 (big-endian) do not support inline PLT calls. On Darwin/PPC systems, "#pragma longcall" generates "jbsr callee, L42", plus a _b_r_a_n_c_h _i_s_l_a_n_d (glue code). The two target addresses represent the callee and the branch island. The Darwin/PPC linker prefers the first address and generates a "bl callee" if the PPC "bl" instruction reaches the callee directly; otherwise, the linker generates "bl L42" to call the branch island. The branch island is appended to the body of the calling function; it computes the full 32-bit address of the callee and jumps to it. On Mach-O (Darwin) systems, this option directs the compiler emit to the glue for every direct call, and the Darwin linker decides whether to use or discard it. In the future, GCC may ignore all longcall specifications when the linker is known to generate glue. --mmppllttsseeqq --mmnnoo--ppllttsseeqq Implement (do not implement) -fno-plt and long calls using an in- line PLT call sequence that supports lazy linking and long calls to functions in dlopen'd shared libraries. Inline PLT calls are only supported on PowerPC64 ELFv2 and 32-bit PowerPC systems with newer GNU linkers, and are enabled by default if the support is detected when configuring GCC, and, in the case of 32-bit PowerPC, if GCC is configured with ----eennaabbllee--sseeccuurreepplltt. --mmppllttsseeqq code and --mmbbssss--pplltt 32-bit PowerPC relocatable objects may not be linked together. --mmttllss--mmaarrkkeerrss --mmnnoo--ttllss--mmaarrkkeerrss Mark (do not mark) calls to "__tls_get_addr" with a relocation specifying the function argument. The relocation allows the linker to reliably associate function call with argument setup instruc- tions for TLS optimization, which in turn allows GCC to better schedule the sequence. --mmrreecciipp --mmnnoo--rreecciipp This option enables use of the reciprocal estimate and reciprocal square root estimate instructions with additional Newton-Raphson steps to increase precision instead of doing a divide or square root and divide for floating-point arguments. You should use the --ffffaasstt--mmaatthh option when using --mmrreecciipp (or at least --ffuunn-- ssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss, --ffffiinniittee--mmaatthh--oonnllyy, --ffrreecciipprrooccaall--mmaatthh and --ffnnoo--ttrraappppiinngg--mmaatthh). Note that while the throughput of the se- quence is generally higher than the throughput of the non-recipro- cal instruction, the precision of the sequence can be decreased by up to 2 ulp (i.e. the inverse of 1.0 equals 0.99999994) for recip- rocal square roots. --mmrreecciipp==_o_p_t This option controls which reciprocal estimate instructions may be used. _o_p_t is a comma-separated list of options, which may be pre- ceded by a "!" to invert the option: aallll Enable all estimate instructions. ddeeffaauulltt Enable the default instructions, equivalent to --mmrreecciipp. nnoonnee Disable all estimate instructions, equivalent to --mmnnoo--rreecciipp. ddiivv Enable the reciprocal approximation instructions for both sin- gle and double precision. ddiivvff Enable the single-precision reciprocal approximation instruc- tions. ddiivvdd Enable the double-precision reciprocal approximation instruc- tions. rrssqqrrtt Enable the reciprocal square root approximation instructions for both single and double precision. rrssqqrrttff Enable the single-precision reciprocal square root approxima- tion instructions. rrssqqrrttdd Enable the double-precision reciprocal square root approxima- tion instructions. So, for example, --mmrreecciipp==aallll,,!!rrssqqrrttdd enables all of the reciprocal estimate instructions, except for the "FRSQRTE", "XSRSQRTEDP", and "XVRSQRTEDP" instructions which handle the double-precision recip- rocal square root calculations. --mmrreecciipp--pprreecciissiioonn --mmnnoo--rreecciipp--pprreecciissiioonn Assume (do not assume) that the reciprocal estimate instructions provide higher-precision estimates than is mandated by the PowerPC ABI. Selecting --mmccppuu==ppoowweerr66, --mmccppuu==ppoowweerr77 or --mmccppuu==ppoowweerr88 automat- ically selects --mmrreecciipp--pprreecciissiioonn. The double-precision square root estimate instructions are not generated by default on low-precision machines, since they do not provide an estimate that converges af- ter three steps. --mmvveecclliibbaabbii==_t_y_p_e Specifies the ABI type to use for vectorizing intrinsics using an external library. The only type supported at present is mmaassss, which specifies to use IBM's Mathematical Acceleration Subsystem (MASS) libraries for vectorizing intrinsics using external li- braries. GCC currently emits calls to "acosd2", "acosf4", "acoshd2", "acoshf4", "asind2", "asinf4", "asinhd2", "asinhf4", "atan2d2", "atan2f4", "atand2", "atanf4", "atanhd2", "atanhf4", "cbrtd2", "cbrtf4", "cosd2", "cosf4", "coshd2", "coshf4", "erfcd2", "erfcf4", "erfd2", "erff4", "exp2d2", "exp2f4", "expd2", "expf4", "expm1d2", "expm1f4", "hypotd2", "hypotf4", "lgammad2", "lgammaf4", "log10d2", "log10f4", "log1pd2", "log1pf4", "log2d2", "log2f4", "logd2", "logf4", "powd2", "powf4", "sind2", "sinf4", "sinhd2", "sinhf4", "sqrtd2", "sqrtf4", "tand2", "tanf4", "tanhd2", and "tanhf4" when generating code for power7. Both --ffttrreeee--vveeccttoorriizzee and --ffuunnssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss must also be enabled. The MASS li- braries must be specified at link time. --mmffrriizz --mmnnoo--ffrriizz Generate (do not generate) the "friz" instruction when the --ffuunn-- ssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss option is used to optimize rounding of floating-point values to 64-bit integer and back to floating point. The "friz" instruction does not return the same value if the float- ing-point number is too large to fit in an integer. --mmppooiinntteerrss--ttoo--nneesstteedd--ffuunnccttiioonnss --mmnnoo--ppooiinntteerrss--ttoo--nneesstteedd--ffuunnccttiioonnss Generate (do not generate) code to load up the static chain regis- ter ("r11") when calling through a pointer on AIX and 64-bit Linux systems where a function pointer points to a 3-word descriptor giv- ing the function address, TOC value to be loaded in register "r2", and static chain value to be loaded in register "r11". The --mmppooiinntteerrss--ttoo--nneesstteedd--ffuunnccttiioonnss is on by default. You cannot call through pointers to nested functions or pointers to functions com- piled in other languages that use the static chain if you use --mmnnoo--ppooiinntteerrss--ttoo--nneesstteedd--ffuunnccttiioonnss. --mmssaavvee--ttoocc--iinnddiirreecctt --mmnnoo--ssaavvee--ttoocc--iinnddiirreecctt Generate (do not generate) code to save the TOC value in the re- served stack location in the function prologue if the function calls through a pointer on AIX and 64-bit Linux systems. If the TOC value is not saved in the prologue, it is saved just before the call through the pointer. The --mmnnoo--ssaavvee--ttoocc--iinnddiirreecctt option is the default. --mmccoommppaatt--aalliiggnn--ppaarrmm --mmnnoo--ccoommppaatt--aalliiggnn--ppaarrmm Generate (do not generate) code to pass structure parameters with a maximum alignment of 64 bits, for compatibility with older versions of GCC. Older versions of GCC (prior to 4.9.0) incorrectly did not align a structure parameter on a 128-bit boundary when that structure con- tained a member requiring 128-bit alignment. This is corrected in more recent versions of GCC. This option may be used to generate code that is compatible with functions compiled with older versions of GCC. The --mmnnoo--ccoommppaatt--aalliiggnn--ppaarrmm option is the default. --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd==_g_u_a_r_d --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--rreegg==_r_e_g --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ooffffsseett==_o_f_f_s_e_t --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ssyymmbbooll==_s_y_m_b_o_l Generate stack protection code using canary at _g_u_a_r_d. Supported locations are gglloobbaall for global canary or ttllss for per-thread canary in the TLS block (the default with GNU libc version 2.4 or later). With the latter choice the options --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--rreegg==_r_e_g and --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ooffffsseett==_o_f_f_s_e_t furthermore specify which register to use as base register for reading the canary, and from what offset from that base register. The default for those is as specified in the relevant ABI. --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ssyymmbbooll==_s_y_m_- _b_o_l overrides the offset with a symbol reference to a canary in the TLS block. --mmppccrreell --mmnnoo--ppccrreell Generate (do not generate) pc-relative addressing. The --mmppccrreell op- tion requires that the medium code model (--mmccmmooddeell==mmeeddiiuumm) and pre- fixed addressing (--mmpprreeffiixxeedd) options are enabled. --mmpprreeffiixxeedd --mmnnoo--pprreeffiixxeedd Generate (do not generate) addressing modes using prefixed load and store instructions. The --mmpprreeffiixxeedd option requires that the option --mmccppuu==ppoowweerr1100 (or later) is enabled. --mmmmmmaa --mmnnoo--mmmmaa Generate (do not generate) the MMA instructions. The --mmmmaa option requires that the option --mmccppuu==ppoowweerr1100 (or later) is enabled. --mmrroopp--pprrootteecctt --mmnnoo--rroopp--pprrootteecctt Generate (do not generate) ROP protection instructions when the target processor supports them. Currently this option disables the shrink-wrap optimization (--ffsshhrriinnkk--wwrraapp). --mmpprriivviilleeggeedd --mmnnoo--pprriivviilleeggeedd Generate (do not generate) code that will run in privileged state. --mmbblloocckk--ooppss--uunnaalliiggnneedd--vvssxx --mmnnoo--bblloocckk--ooppss--uunnaalliiggnneedd--vvssxx Generate (do not generate) unaligned vsx loads and stores for in- line expansion of "memcpy" and "memmove". _R_X _O_p_t_i_o_n_s These command-line options are defined for RX targets: --mm6644bbiitt--ddoouubblleess --mm3322bbiitt--ddoouubblleess Make the "double" data type be 64 bits (--mm6644bbiitt--ddoouubblleess) or 32 bits (--mm3322bbiitt--ddoouubblleess) in size. The default is --mm3322bbiitt--ddoouubblleess. _N_o_t_e RX floating-point hardware only works on 32-bit values, which is why the default is --mm3322bbiitt--ddoouubblleess. --ffppuu --nnooffppuu Enables (--ffppuu) or disables (--nnooffppuu) the use of RX floating-point hardware. The default is enabled for the RX600 series and disabled for the RX200 series. Floating-point instructions are only generated for 32-bit floating- point values, however, so the FPU hardware is not used for doubles if the --mm6644bbiitt--ddoouubblleess option is used. _N_o_t_e If the --ffppuu option is enabled then --ffuunnssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss is also enabled automatically. This is because the RX FPU instruc- tions are themselves unsafe. --mmccppuu==_n_a_m_e Selects the type of RX CPU to be targeted. Currently three types are supported, the generic RRXX660000 and RRXX220000 series hardware and the specific RRXX661100 CPU. The default is RRXX660000. The only difference between RRXX660000 and RRXX661100 is that the RRXX661100 does not support the "MVTIPL" instruction. The RRXX220000 series does not have a hardware floating-point unit and so --nnooffppuu is enabled by default when this type is selected. --mmbbiigg--eennddiiaann--ddaattaa --mmlliittttllee--eennddiiaann--ddaattaa Store data (but not code) in the big-endian format. The default is --mmlliittttllee--eennddiiaann--ddaattaa, i.e. to store data in the little-endian for- mat. --mmssmmaallll--ddaattaa--lliimmiitt==_N Specifies the maximum size in bytes of global and static variables which can be placed into the small data area. Using the small data area can lead to smaller and faster code, but the size of area is limited and it is up to the programmer to ensure that the area does not overflow. Also when the small data area is used one of the RX's registers (usually "r13") is reserved for use pointing to this area, so it is no longer available for use by the compiler. This could result in slower and/or larger code if variables are pushed onto the stack instead of being held in this register. Note, common variables (variables that have not been initialized) and constants are not placed into the small data area as they are assigned to other sections in the output executable. The default value is zero, which disables this feature. Note, this feature is not enabled by default with higher optimization levels (--OO22 etc) because of the potentially detrimental effects of reserv- ing a register. It is up to the programmer to experiment and dis- cover whether this feature is of benefit to their program. See the description of the --mmppiidd option for a description of how the actual register to hold the small data area pointer is chosen. --mmssiimm --mmnnoo--ssiimm Use the simulator runtime. The default is to use the libgloss board-specific runtime. --mmaass110000--ssyynnttaaxx --mmnnoo--aass110000--ssyynnttaaxx When generating assembler output use a syntax that is compatible with Renesas's AS100 assembler. This syntax can also be handled by the GAS assembler, but it has some restrictions so it is not gener- ated by default. --mmmmaaxx--ccoonnssttaanntt--ssiizzee==_N Specifies the maximum size, in bytes, of a constant that can be used as an operand in a RX instruction. Although the RX instruc- tion set does allow constants of up to 4 bytes in length to be used in instructions, a longer value equates to a longer instruction. Thus in some circumstances it can be beneficial to restrict the size of constants that are used in instructions. Constants that are too big are instead placed into a constant pool and referenced via register indirection. The value _N can be between 0 and 4. A value of 0 (the default) or 4 means that constants of any size are allowed. --mmrreellaaxx Enable linker relaxation. Linker relaxation is a process whereby the linker attempts to reduce the size of a program by finding shorter versions of various instructions. Disabled by default. --mmiinntt--rreeggiisstteerr==_N Specify the number of registers to reserve for fast interrupt han- dler functions. The value _N can be between 0 and 4. A value of 1 means that register "r13" is reserved for the exclusive use of fast interrupt handlers. A value of 2 reserves "r13" and "r12". A value of 3 reserves "r13", "r12" and "r11", and a value of 4 re- serves "r13" through "r10". A value of 0, the default, does not reserve any registers. --mmssaavvee--aacccc--iinn--iinntteerrrruuppttss Specifies that interrupt handler functions should preserve the ac- cumulator register. This is only necessary if normal code might use the accumulator register, for example because it performs 64-bit multiplications. The default is to ignore the accumulator as this makes the interrupt handlers faster. --mmppiidd --mmnnoo--ppiidd Enables the generation of position independent data. When enabled any access to constant data is done via an offset from a base ad- dress held in a register. This allows the location of constant data to be determined at run time without requiring the executable to be relocated, which is a benefit to embedded applications with tight memory constraints. Data that can be modified is not af- fected by this option. Note, using this feature reserves a register, usually "r13", for the constant data base address. This can result in slower and/or larger code, especially in complicated functions. The actual register chosen to hold the constant data base address depends upon whether the --mmssmmaallll--ddaattaa--lliimmiitt and/or the --mmiinntt--rreeggiiss-- tteerr command-line options are enabled. Starting with register "r13" and proceeding downwards, registers are allocated first to satisfy the requirements of --mmiinntt--rreeggiisstteerr, then --mmppiidd and finally --mmss-- mmaallll--ddaattaa--lliimmiitt. Thus it is possible for the small data area reg- ister to be "r8" if both --mmiinntt--rreeggiisstteerr==44 and --mmppiidd are specified on the command line. By default this feature is not enabled. The default can be re- stored via the --mmnnoo--ppiidd command-line option. --mmnnoo--wwaarrnn--mmuullttiippllee--ffaasstt--iinntteerrrruuppttss --mmwwaarrnn--mmuullttiippllee--ffaasstt--iinntteerrrruuppttss Prevents GCC from issuing a warning message if it finds more than one fast interrupt handler when it is compiling a file. The de- fault is to issue a warning for each extra fast interrupt handler found, as the RX only supports one such interrupt. --mmaallllooww--ssttrriinngg--iinnssnnss --mmnnoo--aallllooww--ssttrriinngg--iinnssnnss Enables or disables the use of the string manipulation instructions "SMOVF", "SCMPU", "SMOVB", "SMOVU", "SUNTIL" "SWHILE" and also the "RMPA" instruction. These instructions may prefetch data, which is not safe to do if accessing an I/O register. (See section 12.2.7 of the RX62N Group User's Manual for more information). The default is to allow these instructions, but it is not possible for GCC to reliably detect all circumstances where a string in- struction might be used to access an I/O register, so their use cannot be disabled automatically. Instead it is reliant upon the programmer to use the --mmnnoo--aallllooww--ssttrriinngg--iinnssnnss option if their pro- gram accesses I/O space. When the instructions are enabled GCC defines the C preprocessor symbol "__RX_ALLOW_STRING_INSNS__", otherwise it defines the symbol "__RX_DISALLOW_STRING_INSNS__". --mmjjssrr --mmnnoo--jjssrr Use only (or not only) "JSR" instructions to access functions. This option can be used when code size exceeds the range of "BSR" instructions. Note that --mmnnoo--jjssrr does not mean to not use "JSR" but instead means that any type of branch may be used. _N_o_t_e_: The generic GCC command-line option --ffffiixxeedd--_r_e_g has special sig- nificance to the RX port when used with the "interrupt" function attri- bute. This attribute indicates a function intended to process fast in- terrupts. GCC ensures that it only uses the registers "r10", "r11", "r12" and/or "r13" and only provided that the normal use of the corre- sponding registers have been restricted via the --ffffiixxeedd--_r_e_g or --mmiinntt--rreeggiisstteerr command-line options. _S_/_3_9_0 _a_n_d _z_S_e_r_i_e_s _O_p_t_i_o_n_s These are the --mm options defined for the S/390 and zSeries architec- ture. --mmhhaarrdd--ffllooaatt --mmssoofftt--ffllooaatt Use (do not use) the hardware floating-point instructions and reg- isters for floating-point operations. When --mmssoofftt--ffllooaatt is speci- fied, functions in _l_i_b_g_c_c_._a are used to perform floating-point op- erations. When --mmhhaarrdd--ffllooaatt is specified, the compiler generates IEEE floating-point instructions. This is the default. --mmhhaarrdd--ddffpp --mmnnoo--hhaarrdd--ddffpp Use (do not use) the hardware decimal-floating-point instructions for decimal-floating-point operations. When --mmnnoo--hhaarrdd--ddffpp is spec- ified, functions in _l_i_b_g_c_c_._a are used to perform decimal-floating- point operations. When --mmhhaarrdd--ddffpp is specified, the compiler gen- erates decimal-floating-point hardware instructions. This is the default for --mmaarrcchh==zz99--eecc or higher. --mmlloonngg--ddoouubbllee--6644 --mmlloonngg--ddoouubbllee--112288 These switches control the size of "long double" type. A size of 64 bits makes the "long double" type equivalent to the "double" type. This is the default. --mmbbaacckkcchhaaiinn --mmnnoo--bbaacckkcchhaaiinn Store (do not store) the address of the caller's frame as backchain pointer into the callee's stack frame. A backchain may be needed to allow debugging using tools that do not understand DWARF call frame information. When --mmnnoo--ppaacckkeedd--ssttaacckk is in effect, the backchain pointer is stored at the bottom of the stack frame; when --mmppaacckkeedd--ssttaacckk is in effect, the backchain is placed into the top- most word of the 96/160 byte register save area. In general, code compiled with --mmbbaacckkcchhaaiinn is call-compatible with code compiled with --mmnnoo--bbaacckkcchhaaiinn; however, use of the backchain for debugging purposes usually requires that the whole binary is built with --mmbbaacckkcchhaaiinn. Note that the combination of --mmbbaacckkcchhaaiinn, --mmppaacckkeedd--ssttaacckk and --mmhhaarrdd--ffllooaatt is not supported. In order to build a linux kernel use --mmssoofftt--ffllooaatt. The default is to not maintain the backchain. --mmppaacckkeedd--ssttaacckk --mmnnoo--ppaacckkeedd--ssttaacckk Use (do not use) the packed stack layout. When --mmnnoo--ppaacckkeedd--ssttaacckk is specified, the compiler uses the all fields of the 96/160 byte register save area only for their default purpose; unused fields still take up stack space. When --mmppaacckkeedd--ssttaacckk is specified, reg- ister save slots are densely packed at the top of the register save area; unused space is reused for other purposes, allowing for more efficient use of the available stack space. However, when --mmbbaacckkcchhaaiinn is also in effect, the topmost word of the save area is always used to store the backchain, and the return address register is always saved two words below the backchain. As long as the stack frame backchain is not used, code generated with --mmppaacckkeedd--ssttaacckk is call-compatible with code generated with --mmnnoo--ppaacckkeedd--ssttaacckk. Note that some non-FSF releases of GCC 2.95 for S/390 or zSeries generated code that uses the stack frame backchain at run time, not just for debugging purposes. Such code is not call-compatible with code compiled with --mmppaacckkeedd--ssttaacckk. Also, note that the combination of --mmbbaacckkcchhaaiinn, --mmppaacckkeedd--ssttaacckk and --mmhhaarrdd--ffllooaatt is not supported. In order to build a linux kernel use --mmssoofftt--ffllooaatt. The default is to not use the packed stack layout. --mmssmmaallll--eexxeecc --mmnnoo--ssmmaallll--eexxeecc Generate (or do not generate) code using the "bras" instruction to do subroutine calls. This only works reliably if the total exe- cutable size does not exceed 64k. The default is to use the "basr" instruction instead, which does not have this limitation. --mm6644 --mm3311 When --mm3311 is specified, generate code compliant to the GNU/Linux for S/390 ABI. When --mm6644 is specified, generate code compliant to the GNU/Linux for zSeries ABI. This allows GCC in particular to generate 64-bit instructions. For the ss339900 targets, the default is --mm3311, while the ss339900xx targets default to --mm6644. --mmzzaarrcchh --mmeessaa When --mmzzaarrcchh is specified, generate code using the instructions available on z/Architecture. When --mmeessaa is specified, generate code using the instructions available on ESA/390. Note that --mmeessaa is not possible with --mm6644. When generating code compliant to the GNU/Linux for S/390 ABI, the default is --mmeessaa. When generating code compliant to the GNU/Linux for zSeries ABI, the default is --mmzzaarrcchh. --mmhhttmm --mmnnoo--hhttmm The --mmhhttmm option enables a set of builtins making use of instruc- tions available with the transactional execution facility intro- duced with the IBM zEnterprise EC12 machine generation SS//339900 SSyysstteemm zz BBuuiilltt--iinn FFuunnccttiioonnss. --mmhhttmm is enabled by default when using --mmaarrcchh==zzEECC1122. --mmvvxx --mmnnoo--vvxx When --mmvvxx is specified, generate code using the instructions avail- able with the vector extension facility introduced with the IBM z13 machine generation. This option changes the ABI for some vector type values with regard to alignment and calling conventions. In case vector type values are being used in an ABI-relevant context a GAS ..ggnnuu__aattttrriibbuuttee command will be added to mark the resulting bi- nary with the ABI used. --mmvvxx is enabled by default when using --mmaarrcchh==zz1133. --mmzzvveeccttoorr --mmnnoo--zzvveeccttoorr The --mmzzvveeccttoorr option enables vector language extensions and builtins using instructions available with the vector extension fa- cility introduced with the IBM z13 machine generation. This option adds support for vveeccttoorr to be used as a keyword to define vector type variables and arguments. vveeccttoorr is only available when GNU extensions are enabled. It will not be expanded when requesting strict standard compliance e.g. with --ssttdd==cc9999. In addition to the GCC low-level builtins --mmzzvveeccttoorr enables a set of builtins added for compatibility with AltiVec-style implementations like Power and Cell. In order to make use of these builtins the header file _v_e_c_i_n_t_r_i_n_._h needs to be included. --mmzzvveeccttoorr is disabled by de- fault. --mmmmvvccllee --mmnnoo--mmvvccllee Generate (or do not generate) code using the "mvcle" instruction to perform block moves. When --mmnnoo--mmvvccllee is specified, use a "mvc" loop instead. This is the default unless optimizing for size. --mmddeebbuugg --mmnnoo--ddeebbuugg Print (or do not print) additional debug information when compil- ing. The default is to not print debug information. --mmaarrcchh==_c_p_u_-_t_y_p_e Generate code that runs on _c_p_u_-_t_y_p_e, which is the name of a system representing a certain processor type. Possible values for _c_p_u_- _t_y_p_e are zz990000/aarrcchh55, zz999900/aarrcchh66, zz99--110099, zz99--eecc/aarrcchh77, zz1100/aarrcchh88, zz119966/aarrcchh99, zzEECC1122, zz1133/aarrcchh1111, zz1144/aarrcchh1122, zz1155/aarrcchh1133, zz1166/aarrcchh1144, and nnaattiivvee. The default is --mmaarrcchh==zz990000. Specifying nnaattiivvee as cpu type can be used to select the best archi- tecture option for the host processor. --mmaarrcchh==nnaattiivvee has no effect if GCC does not recognize the processor. --mmttuunnee==_c_p_u_-_t_y_p_e Tune to _c_p_u_-_t_y_p_e everything applicable about the generated code, except for the ABI and the set of available instructions. The list of _c_p_u_-_t_y_p_e values is the same as for --mmaarrcchh. The default is the value used for --mmaarrcchh. --mmttppff--ttrraaccee --mmnnoo--ttppff--ttrraaccee Generate code that adds (does not add) in TPF OS specific branches to trace routines in the operating system. This option is off by default, even when compiling for the TPF OS. --mmttppff--ttrraaccee--sskkiipp --mmnnoo--ttppff--ttrraaccee--sskkiipp Generate code that changes (does not change) the default branch targets enabled by --mmttppff--ttrraaccee to point to specialized trace rou- tines providing the ability of selectively skipping function trace entries for the TPF OS. This option is off by default, even when compiling for the TPF OS and specifying --mmttppff--ttrraaccee. --mmffuusseedd--mmaadddd --mmnnoo--ffuusseedd--mmaadddd Generate code that uses (does not use) the floating-point multiply and accumulate instructions. These instructions are generated by default if hardware floating point is used. --mmwwaarrnn--ffrraammeessiizzee==_f_r_a_m_e_s_i_z_e Emit a warning if the current function exceeds the given frame size. Because this is a compile-time check it doesn't need to be a real problem when the program runs. It is intended to identify functions that most probably cause a stack overflow. It is useful to be used in an environment with limited stack size e.g. the linux kernel. --mmwwaarrnn--ddyynnaammiiccssttaacckk Emit a warning if the function calls "alloca" or uses dynamically- sized arrays. This is generally a bad idea with a limited stack size. --mmssttaacckk--gguuaarrdd==_s_t_a_c_k_-_g_u_a_r_d --mmssttaacckk--ssiizzee==_s_t_a_c_k_-_s_i_z_e If these options are provided the S/390 back end emits additional instructions in the function prologue that trigger a trap if the stack size is _s_t_a_c_k_-_g_u_a_r_d bytes above the _s_t_a_c_k_-_s_i_z_e (remember that the stack on S/390 grows downward). If the _s_t_a_c_k_-_g_u_a_r_d option is omitted the smallest power of 2 larger than the frame size of the compiled function is chosen. These options are intended to be used to help debugging stack overflow problems. The additionally emit- ted code causes only little overhead and hence can also be used in production-like systems without greater performance degradation. The given values have to be exact powers of 2 and _s_t_a_c_k_-_s_i_z_e has to be greater than _s_t_a_c_k_-_g_u_a_r_d without exceeding 64k. In order to be efficient the extra code makes the assumption that the stack starts at an address aligned to the value given by _s_t_a_c_k_-_s_i_z_e. The _s_t_a_c_k_- _g_u_a_r_d option can only be used in conjunction with _s_t_a_c_k_-_s_i_z_e. --mmhhoottppaattcchh==_p_r_e_-_h_a_l_f_w_o_r_d_s,,_p_o_s_t_-_h_a_l_f_w_o_r_d_s If the hotpatch option is enabled, a "hot-patching" function pro- logue is generated for all functions in the compilation unit. The funtion label is prepended with the given number of two-byte NOP instructions (_p_r_e_-_h_a_l_f_w_o_r_d_s, maximum 1000000). After the label, 2 * _p_o_s_t_-_h_a_l_f_w_o_r_d_s bytes are appended, using the largest NOP like in- structions the architecture allows (maximum 1000000). If both arguments are zero, hotpatching is disabled. This option can be overridden for individual functions with the "hotpatch" attribute. _S_c_o_r_e _O_p_t_i_o_n_s These options are defined for Score implementations: --mmeebb Compile code for big-endian mode. This is the default. --mmeell Compile code for little-endian mode. --mmnnhhwwlloooopp Disable generation of "bcnz" instructions. --mmuullss Enable generation of unaligned load and store instructions. --mmmmaacc Enable the use of multiply-accumulate instructions. Disabled by de- fault. --mmssccoorree55 Specify the SCORE5 as the target architecture. --mmssccoorree55uu Specify the SCORE5U of the target architecture. --mmssccoorree77 Specify the SCORE7 as the target architecture. This is the default. --mmssccoorree77dd Specify the SCORE7D as the target architecture. _S_H _O_p_t_i_o_n_s These --mm options are defined for the SH implementations: --mm11 Generate code for the SH1. --mm22 Generate code for the SH2. --mm22ee Generate code for the SH2e. --mm22aa--nnooffppuu Generate code for the SH2a without FPU, or for a SH2a-FPU in such a way that the floating-point unit is not used. --mm22aa--ssiinnggllee--oonnllyy Generate code for the SH2a-FPU, in such a way that no double-preci- sion floating-point operations are used. --mm22aa--ssiinnggllee Generate code for the SH2a-FPU assuming the floating-point unit is in single-precision mode by default. --mm22aa Generate code for the SH2a-FPU assuming the floating-point unit is in double-precision mode by default. --mm33 Generate code for the SH3. --mm33ee Generate code for the SH3e. --mm44--nnooffppuu Generate code for the SH4 without a floating-point unit. --mm44--ssiinnggllee--oonnllyy Generate code for the SH4 with a floating-point unit that only sup- ports single-precision arithmetic. --mm44--ssiinnggllee Generate code for the SH4 assuming the floating-point unit is in single-precision mode by default. --mm44 Generate code for the SH4. --mm44--110000 Generate code for SH4-100. --mm44--110000--nnooffppuu Generate code for SH4-100 in such a way that the floating-point unit is not used. --mm44--110000--ssiinnggllee Generate code for SH4-100 assuming the floating-point unit is in single-precision mode by default. --mm44--110000--ssiinnggllee--oonnllyy Generate code for SH4-100 in such a way that no double-precision floating-point operations are used. --mm44--220000 Generate code for SH4-200. --mm44--220000--nnooffppuu Generate code for SH4-200 without in such a way that the floating- point unit is not used. --mm44--220000--ssiinnggllee Generate code for SH4-200 assuming the floating-point unit is in single-precision mode by default. --mm44--220000--ssiinnggllee--oonnllyy Generate code for SH4-200 in such a way that no double-precision floating-point operations are used. --mm44--330000 Generate code for SH4-300. --mm44--330000--nnooffppuu Generate code for SH4-300 without in such a way that the floating- point unit is not used. --mm44--330000--ssiinnggllee Generate code for SH4-300 in such a way that no double-precision floating-point operations are used. --mm44--330000--ssiinnggllee--oonnllyy Generate code for SH4-300 in such a way that no double-precision floating-point operations are used. --mm44--334400 Generate code for SH4-340 (no MMU, no FPU). --mm44--550000 Generate code for SH4-500 (no FPU). Passes --iissaa==sshh44--nnooffppuu to the assembler. --mm44aa--nnooffppuu Generate code for the SH4al-dsp, or for a SH4a in such a way that the floating-point unit is not used. --mm44aa--ssiinnggllee--oonnllyy Generate code for the SH4a, in such a way that no double-precision floating-point operations are used. --mm44aa--ssiinnggllee Generate code for the SH4a assuming the floating-point unit is in single-precision mode by default. --mm44aa Generate code for the SH4a. --mm44aall Same as --mm44aa--nnooffppuu, except that it implicitly passes --ddsspp to the assembler. GCC doesn't generate any DSP instructions at the mo- ment. --mmbb Compile code for the processor in big-endian mode. --mmll Compile code for the processor in little-endian mode. --mmddaalliiggnn Align doubles at 64-bit boundaries. Note that this changes the calling conventions, and thus some functions from the standard C library do not work unless you recompile it first with --mmddaalliiggnn. --mmrreellaaxx Shorten some address references at link time, when possible; uses the linker option --rreellaaxx. --mmbbiiggttaabbllee Use 32-bit offsets in "switch" tables. The default is to use 16-bit offsets. --mmbbiittooppss Enable the use of bit manipulation instructions on SH2A. --mmffmmoovvdd Enable the use of the instruction "fmovd". Check --mmddaalliiggnn for alignment constraints. --mmrreenneessaass Comply with the calling conventions defined by Renesas. --mmnnoo--rreenneessaass Comply with the calling conventions defined for GCC before the Re- nesas conventions were available. This option is the default for all targets of the SH toolchain. --mmnnoommaaccssaavvee Mark the "MAC" register as call-clobbered, even if --mmrreenneessaass is given. --mmiieeeeee --mmnnoo--iieeeeee Control the IEEE compliance of floating-point comparisons, which affects the handling of cases where the result of a comparison is unordered. By default --mmiieeeeee is implicitly enabled. If --ffffii-- nniittee--mmaatthh--oonnllyy is enabled --mmnnoo--iieeeeee is implicitly set, which re- sults in faster floating-point greater-equal and less-equal compar- isons. The implicit settings can be overridden by specifying ei- ther --mmiieeeeee or --mmnnoo--iieeeeee. --mmiinnlliinnee--iicc__iinnvvaalliiddaattee Inline code to invalidate instruction cache entries after setting up nested function trampolines. This option has no effect if --mmuusseerrmmooddee is in effect and the selected code generation option (e.g. --mm44) does not allow the use of the "icbi" instruction. If the selected code generation option does not allow the use of the "icbi" instruction, and --mmuusseerrmmooddee is not in effect, the inlined code manipulates the instruction cache address array directly with an associative write. This not only requires privileged mode at run time, but it also fails if the cache line had been mapped via the TLB and has become unmapped. --mmiissiizzee Dump instruction size and location in the assembly code. --mmppaaddssttrruucctt This option is deprecated. It pads structures to multiple of 4 bytes, which is incompatible with the SH ABI. --mmaattoommiicc--mmooddeell==_m_o_d_e_l Sets the model of atomic operations and additional parameters as a comma separated list. For details on the atomic built-in functions see ____aattoommiicc BBuuiillttiinnss. The following models and parameters are supported: nnoonnee Disable compiler generated atomic sequences and emit library calls for atomic operations. This is the default if the target is not "sh*-*-linux*". ssoofftt--gguussaa Generate GNU/Linux compatible gUSA software atomic sequences for the atomic built-in functions. The generated atomic se- quences require additional support from the interrupt/exception handling code of the system and are only suitable for SH3* and SH4* single-core systems. This option is enabled by default when the target is "sh*-*-linux*" and SH3* or SH4*. When the target is SH4A, this option also partially utilizes the hard- ware atomic instructions "movli.l" and "movco.l" to create more efficient code, unless ssttrriicctt is specified. ssoofftt--ttccbb Generate software atomic sequences that use a variable in the thread control block. This is a variation of the gUSA se- quences which can also be used on SH1* and SH2* targets. The generated atomic sequences require additional support from the interrupt/exception handling code of the system and are only suitable for single-core systems. When using this model, the ggbbrr--ooffffsseett== parameter has to be specified as well. ssoofftt--iimmaasskk Generate software atomic sequences that temporarily disable in- terrupts by setting "SR.IMASK = 1111". This model works only when the program runs in privileged mode and is only suitable for single-core systems. Additional support from the inter- rupt/exception handling code of the system is not required. This model is enabled by default when the target is "sh*-*-linux*" and SH1* or SH2*. hhaarrdd--llllccss Generate hardware atomic sequences using the "movli.l" and "movco.l" instructions only. This is only available on SH4A and is suitable for multi-core systems. Since the hardware in- structions support only 32 bit atomic variables access to 8 or 16 bit variables is emulated with 32 bit accesses. Code com- piled with this option is also compatible with other software atomic model interrupt/exception handling systems if executed on an SH4A system. Additional support from the interrupt/ex- ception handling code of the system is not required for this model. ggbbrr--ooffffsseett== This parameter specifies the offset in bytes of the variable in the thread control block structure that should be used by the generated atomic sequences when the ssoofftt--ttccbb model has been se- lected. For other models this parameter is ignored. The spec- ified value must be an integer multiple of four and in the range 0-1020. ssttrriicctt This parameter prevents mixed usage of multiple atomic models, even if they are compatible, and makes the compiler generate atomic sequences of the specified model only. --mmttaass Generate the "tas.b" opcode for "__atomic_test_and_set". Notice that depending on the particular hardware and software configura- tion this can degrade overall performance due to the operand cache line flushes that are implied by the "tas.b" instruction. On multi-core SH4A processors the "tas.b" instruction must be used with caution since it can result in data corruption for certain cache configurations. --mmpprreeffeerrggoott When generating position-independent code, emit function calls us- ing the Global Offset Table instead of the Procedure Linkage Table. --mmuusseerrmmooddee --mmnnoo--uusseerrmmooddee Don't allow (allow) the compiler generating privileged mode code. Specifying --mmuusseerrmmooddee also implies --mmnnoo--iinnlliinnee--iicc__iinnvvaalliiddaattee if the inlined code would not work in user mode. --mmuusseerrmmooddee is the de- fault when the target is "sh*-*-linux*". If the target is SH1* or SH2* --mmuusseerrmmooddee has no effect, since there is no user mode. --mmuullttccoosstt==_n_u_m_b_e_r Set the cost to assume for a multiply insn. --mmddiivv==_s_t_r_a_t_e_g_y Set the division strategy to be used for integer division opera- tions. _s_t_r_a_t_e_g_y can be one of: ccaallll--ddiivv11 Calls a library function that uses the single-step division in- struction "div1" to perform the operation. Division by zero calculates an unspecified result and does not trap. This is the default except for SH4, SH2A and SHcompact. ccaallll--ffpp Calls a library function that performs the operation in double precision floating point. Division by zero causes a floating- point exception. This is the default for SHcompact with FPU. Specifying this for targets that do not have a double precision FPU defaults to "call-div1". ccaallll--ttaabbllee Calls a library function that uses a lookup table for small di- visors and the "div1" instruction with case distinction for larger divisors. Division by zero calculates an unspecified result and does not trap. This is the default for SH4. Speci- fying this for targets that do not have dynamic shift instruc- tions defaults to "call-div1". When a division strategy has not been specified the default strat- egy is selected based on the current target. For SH2A the default strategy is to use the "divs" and "divu" instructions instead of library function calls. --mmaaccccuummuullaattee--oouuttggooiinngg--aarrggss Reserve space once for outgoing arguments in the function prologue rather than around each call. Generally beneficial for performance and size. Also needed for unwinding to avoid changing the stack frame around conditional code. --mmddiivvssii33__lliibbffuunncc==_n_a_m_e Set the name of the library function used for 32-bit signed divi- sion to _n_a_m_e. This only affects the name used in the ccaallll division strategies, and the compiler still expects the same sets of in- put/output/clobbered registers as if this option were not present. --mmffiixxeedd--rraannggee==_r_e_g_i_s_t_e_r_-_r_a_n_g_e Generate code treating the given register range as fixed registers. A fixed register is one that the register allocator cannot use. This is useful when compiling kernel code. A register range is specified as two registers separated by a dash. Multiple register ranges can be specified separated by a comma. --mmbbrraanncchh--ccoosstt==_n_u_m Assume _n_u_m to be the cost for a branch instruction. Higher numbers make the compiler try to generate more branch-free code if possi- ble. If not specified the value is selected depending on the pro- cessor type that is being compiled for. --mmzzddccbbrraanncchh --mmnnoo--zzddccbbrraanncchh Assume (do not assume) that zero displacement conditional branch instructions "bt" and "bf" are fast. If --mmzzddccbbrraanncchh is specified, the compiler prefers zero displacement branch code sequences. This is enabled by default when generating code for SH4 and SH4A. It can be explicitly disabled by specifying --mmnnoo--zzddccbbrraanncchh. --mmccbbrraanncchh--ffoorrccee--ddeellaayy--sslloott Force the usage of delay slots for conditional branches, which stuffs the delay slot with a "nop" if a suitable instruction cannot be found. By default this option is disabled. It can be enabled to work around hardware bugs as found in the original SH7055. --mmffuusseedd--mmaadddd --mmnnoo--ffuusseedd--mmaadddd Generate code that uses (does not use) the floating-point multiply and accumulate instructions. These instructions are generated by default if hardware floating point is used. The machine-dependent --mmffuusseedd--mmaadddd option is now mapped to the machine-independent --ffffpp--ccoonnttrraacctt==ffaasstt option, and --mmnnoo--ffuusseedd--mmaadddd is mapped to --ffffpp--ccoonnttrraacctt==ooffff. --mmffssccaa --mmnnoo--ffssccaa Allow or disallow the compiler to emit the "fsca" instruction for sine and cosine approximations. The option --mmffssccaa must be used in combination with --ffuunnssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss. It is enabled by de- fault when generating code for SH4A. Using --mmnnoo--ffssccaa disables sine and cosine approximations even if --ffuunnssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss is in effect. --mmffssrrrraa --mmnnoo--ffssrrrraa Allow or disallow the compiler to emit the "fsrra" instruction for reciprocal square root approximations. The option --mmffssrrrraa must be used in combination with --ffuunnssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss and --ffffii-- nniittee--mmaatthh--oonnllyy. It is enabled by default when generating code for SH4A. Using --mmnnoo--ffssrrrraa disables reciprocal square root approxima- tions even if --ffuunnssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss and --ffffiinniittee--mmaatthh--oonnllyy are in effect. --mmpprreetteenndd--ccmmoovvee Prefer zero-displacement conditional branches for conditional move instruction patterns. This can result in faster code on the SH4 processor. --mmffddppiicc Generate code using the FDPIC ABI. _S_o_l_a_r_i_s _2 _O_p_t_i_o_n_s These --mm options are supported on Solaris 2: --mmcclleeaarr--hhwwccaapp --mmcclleeaarr--hhwwccaapp tells the compiler to remove the hardware capabili- ties generated by the Solaris assembler. This is only necessary when object files use ISA extensions not supported by the current machine, but check at runtime whether or not to use them. --mmiimmppuurree--tteexxtt --mmiimmppuurree--tteexxtt, used in addition to --sshhaarreedd, tells the compiler to not pass --zz tteexxtt to the linker when linking a shared object. Using this option, you can link position-dependent code into a shared ob- ject. --mmiimmppuurree--tteexxtt suppresses the "relocations remain against allocat- able but non-writable sections" linker error message. However, the necessary relocations trigger copy-on-write, and the shared object is not actually shared across processes. Instead of using --mmiimm-- ppuurree--tteexxtt, you should compile all source code with --ffppiicc or --ffPPIICC. These switches are supported in addition to the above on Solaris 2: --pptthhrreeaaddss This is a synonym for --pptthhrreeaadd. _S_P_A_R_C _O_p_t_i_o_n_s These --mm options are supported on the SPARC: --mmnnoo--aapppp--rreeggss --mmaapppp--rreeggss Specify --mmaapppp--rreeggss to generate output using the global registers 2 through 4, which the SPARC SVR4 ABI reserves for applications. Like the global register 1, each global register 2 through 4 is then treated as an allocable register that is clobbered by function calls. This is the default. To be fully SVR4 ABI-compliant at the cost of some performance loss, specify --mmnnoo--aapppp--rreeggss. You should compile libraries and sys- tem software with this option. --mmffllaatt --mmnnoo--ffllaatt With --mmffllaatt, the compiler does not generate save/restore instruc- tions and uses a "flat" or single register window model. This model is compatible with the regular register window model. The local registers and the input registers (0--5) are still treated as "call-saved" registers and are saved on the stack as needed. With --mmnnoo--ffllaatt (the default), the compiler generates save/restore instructions (except for leaf functions). This is the normal oper- ating mode. --mmffppuu --mmhhaarrdd--ffllooaatt Generate output containing floating-point instructions. This is the default. --mmnnoo--ffppuu --mmssoofftt--ffllooaatt Generate output containing library calls for floating point. WWaarrnn-- iinngg:: the requisite libraries are not available for all SPARC tar- gets. Normally the facilities of the machine's usual C compiler are used, but this cannot be done directly in cross-compilation. You must make your own arrangements to provide suitable library functions for cross-compilation. The embedded targets ssppaarrcc--**--aaoouutt and ssppaarrcclliittee--**--** do provide software floating-point support. --mmssoofftt--ffllooaatt changes the calling convention in the output file; therefore, it is only useful if you compile _a_l_l of a program with this option. In particular, you need to compile _l_i_b_g_c_c_._a, the li- brary that comes with GCC, with --mmssoofftt--ffllooaatt in order for this to work. --mmhhaarrdd--qquuaadd--ffllooaatt Generate output containing quad-word (long double) floating-point instructions. --mmssoofftt--qquuaadd--ffllooaatt Generate output containing library calls for quad-word (long dou- ble) floating-point instructions. The functions called are those specified in the SPARC ABI. This is the default. As of this writing, there are no SPARC implementations that have hardware support for the quad-word floating-point instructions. They all invoke a trap handler for one of these instructions, and then the trap handler emulates the effect of the instruction. Be- cause of the trap handler overhead, this is much slower than call- ing the ABI library routines. Thus the --mmssoofftt--qquuaadd--ffllooaatt option is the default. --mmnnoo--uunnaalliiggnneedd--ddoouubblleess --mmuunnaalliiggnneedd--ddoouubblleess Assume that doubles have 8-byte alignment. This is the default. With --mmuunnaalliiggnneedd--ddoouubblleess, GCC assumes that doubles have 8-byte alignment only if they are contained in another type, or if they have an absolute address. Otherwise, it assumes they have 4-byte alignment. Specifying this option avoids some rare compatibility problems with code generated by other compilers. It is not the de- fault because it results in a performance loss, especially for floating-point code. --mmuusseerr--mmooddee --mmnnoo--uusseerr--mmooddee Do not generate code that can only run in supervisor mode. This is relevant only for the "casa" instruction emitted for the LEON3 pro- cessor. This is the default. --mmffaasstteerr--ssttrruuccttss --mmnnoo--ffaasstteerr--ssttrruuccttss With --mmffaasstteerr--ssttrruuccttss, the compiler assumes that structures should have 8-byte alignment. This enables the use of pairs of "ldd" and "std" instructions for copies in structure assignment, in place of twice as many "ld" and "st" pairs. However, the use of this changed alignment directly violates the SPARC ABI. Thus, it's in- tended only for use on targets where the developer acknowledges that their resulting code is not directly in line with the rules of the ABI. --mmssttdd--ssttrruucctt--rreettuurrnn --mmnnoo--ssttdd--ssttrruucctt--rreettuurrnn With --mmssttdd--ssttrruucctt--rreettuurrnn, the compiler generates checking code in functions returning structures or unions to detect size mismatches between the two sides of function calls, as per the 32-bit ABI. The default is --mmnnoo--ssttdd--ssttrruucctt--rreettuurrnn. This option has no effect in 64-bit mode. --mmllrraa --mmnnoo--llrraa Enable Local Register Allocation. This is the default for SPARC since GCC 7 so --mmnnoo--llrraa needs to be passed to get old Reload. --mmccppuu==_c_p_u___t_y_p_e Set the instruction set, register set, and instruction scheduling parameters for machine type _c_p_u___t_y_p_e. Supported values for _c_p_u___t_y_p_e are vv77, ccyypprreessss, vv88, ssuuppeerrssppaarrcc, hhyyppeerrssppaarrcc, lleeoonn, lleeoonn33, lleeoonn33vv77, lleeoonn55, ssppaarrcclliittee, ff993300, ff993344, ssppaarrcclliittee8866xx, ssppaarrcclleett, ttsscc770011, vv99, uullttrraassppaarrcc, uullttrraassppaarrcc33, nniiaaggaarraa, nniiaaggaarraa22, nniiaaggaarraa33, nniiaaggaarraa44, nniiaaggaarraa77 and mm88. Native Solaris and GNU/Linux toolchains also support the value nnaa-- ttiivvee, which selects the best architecture option for the host pro- cessor. --mmccppuu==nnaattiivvee has no effect if GCC does not recognize the processor. Default instruction scheduling parameters are used for values that select an architecture and not an implementation. These are vv77, vv88, ssppaarrcclliittee, ssppaarrcclleett, vv99. Here is a list of each supported architecture and their supported implementations. v7 cypress, leon3v7 v8 supersparc, hypersparc, leon, leon3, leon5 sparclite f930, f934, sparclite86x sparclet tsc701 v9 ultrasparc, ultrasparc3, niagara, niagara2, niagara3, niagara4, niagara7, m8 By default (unless configured otherwise), GCC generates code for the V7 variant of the SPARC architecture. With --mmccppuu==ccyypprreessss, the compiler additionally optimizes it for the Cypress CY7C602 chip, as used in the SPARCStation/SPARCServer 3xx series. This is also ap- propriate for the older SPARCStation 1, 2, IPX etc. With --mmccppuu==vv88, GCC generates code for the V8 variant of the SPARC architecture. The only difference from V7 code is that the com- piler emits the integer multiply and integer divide instructions which exist in SPARC-V8 but not in SPARC-V7. With --mmccppuu==ssuuppeerr-- ssppaarrcc, the compiler additionally optimizes it for the SuperSPARC chip, as used in the SPARCStation 10, 1000 and 2000 series. With --mmccppuu==ssppaarrcclliittee, GCC generates code for the SPARClite variant of the SPARC architecture. This adds the integer multiply, integer divide step and scan ("ffs") instructions which exist in SPARClite but not in SPARC-V7. With --mmccppuu==ff993300, the compiler additionally optimizes it for the Fujitsu MB86930 chip, which is the original SPARClite, with no FPU. With --mmccppuu==ff993344, the compiler additionally optimizes it for the Fujitsu MB86934 chip, which is the more recent SPARClite with FPU. With --mmccppuu==ssppaarrcclleett, GCC generates code for the SPARClet variant of the SPARC architecture. This adds the integer multiply, multi- ply/accumulate, integer divide step and scan ("ffs") instructions which exist in SPARClet but not in SPARC-V7. With --mmccppuu==ttsscc770011, the compiler additionally optimizes it for the TEMIC SPARClet chip. With --mmccppuu==vv99, GCC generates code for the V9 variant of the SPARC architecture. This adds 64-bit integer and floating-point move in- structions, 3 additional floating-point condition code registers and conditional move instructions. With --mmccppuu==uullttrraassppaarrcc, the com- piler additionally optimizes it for the Sun UltraSPARC I/II/IIi chips. With --mmccppuu==uullttrraassppaarrcc33, the compiler additionally optimizes it for the Sun UltraSPARC III/III+/IIIi/IIIi+/IV/IV+ chips. With --mmccppuu==nniiaaggaarraa, the compiler additionally optimizes it for Sun Ul- traSPARC T1 chips. With --mmccppuu==nniiaaggaarraa22, the compiler additionally optimizes it for Sun UltraSPARC T2 chips. With --mmccppuu==nniiaaggaarraa33, the compiler additionally optimizes it for Sun UltraSPARC T3 chips. With --mmccppuu==nniiaaggaarraa44, the compiler additionally optimizes it for Sun UltraSPARC T4 chips. With --mmccppuu==nniiaaggaarraa77, the compiler addition- ally optimizes it for Oracle SPARC M7 chips. With --mmccppuu==mm88, the compiler additionally optimizes it for Oracle M8 chips. --mmttuunnee==_c_p_u___t_y_p_e Set the instruction scheduling parameters for machine type _c_p_u___t_y_p_e, but do not set the instruction set or register set that the option --mmccppuu==_c_p_u___t_y_p_e does. The same values for --mmccppuu==_c_p_u___t_y_p_e can be used for --mmttuunnee==_c_p_u___t_y_p_e, but the only useful values are those that select a particular CPU implementation. Those are ccyypprreessss, ssuuppeerrssppaarrcc, hhyyppeerrssppaarrcc, lleeoonn, lleeoonn33, lleeoonn33vv77, lleeoonn55, ff993300, ff993344, ssppaarrcclliittee8866xx, ttsscc770011, uullttrraa-- ssppaarrcc, uullttrraassppaarrcc33, nniiaaggaarraa, nniiaaggaarraa22, nniiaaggaarraa33, nniiaaggaarraa44, nniiaaggaarraa77 and mm88. With native Solaris and GNU/Linux toolchains, nnaattiivvee can also be used. --mmvv88pplluuss --mmnnoo--vv88pplluuss With --mmvv88pplluuss, GCC generates code for the SPARC-V8+ ABI. The dif- ference from the V8 ABI is that the global and out registers are considered 64 bits wide. This is enabled by default on Solaris in 32-bit mode for all SPARC-V9 processors. --mmvviiss --mmnnoo--vviiss With --mmvviiss, GCC generates code that takes advantage of the Ultra- SPARC Visual Instruction Set extensions. The default is --mmnnoo--vviiss. --mmvviiss22 --mmnnoo--vviiss22 With --mmvviiss22, GCC generates code that takes advantage of version 2.0 of the UltraSPARC Visual Instruction Set extensions. The default is --mmvviiss22 when targeting a cpu that supports such instructions, such as UltraSPARC-III and later. Setting --mmvviiss22 also sets --mmvviiss. --mmvviiss33 --mmnnoo--vviiss33 With --mmvviiss33, GCC generates code that takes advantage of version 3.0 of the UltraSPARC Visual Instruction Set extensions. The default is --mmvviiss33 when targeting a cpu that supports such instructions, such as niagara-3 and later. Setting --mmvviiss33 also sets --mmvviiss22 and --mmvviiss. --mmvviiss44 --mmnnoo--vviiss44 With --mmvviiss44, GCC generates code that takes advantage of version 4.0 of the UltraSPARC Visual Instruction Set extensions. The default is --mmvviiss44 when targeting a cpu that supports such instructions, such as niagara-7 and later. Setting --mmvviiss44 also sets --mmvviiss33, --mmvviiss22 and --mmvviiss. --mmvviiss44bb --mmnnoo--vviiss44bb With --mmvviiss44bb, GCC generates code that takes advantage of version 4.0 of the UltraSPARC Visual Instruction Set extensions, plus the additional VIS instructions introduced in the Oracle SPARC Archi- tecture 2017. The default is --mmvviiss44bb when targeting a cpu that supports such instructions, such as m8 and later. Setting --mmvviiss44bb also sets --mmvviiss44, --mmvviiss33, --mmvviiss22 and --mmvviiss. --mmccbbccoonndd --mmnnoo--ccbbccoonndd With --mmccbbccoonndd, GCC generates code that takes advantage of the Ul- traSPARC Compare-and-Branch-on-Condition instructions. The default is --mmccbbccoonndd when targeting a CPU that supports such instructions, such as Niagara-4 and later. --mmffmmaaff --mmnnoo--ffmmaaff With --mmffmmaaff, GCC generates code that takes advantage of the Ultra- SPARC Fused Multiply-Add Floating-point instructions. The default is --mmffmmaaff when targeting a CPU that supports such instructions, such as Niagara-3 and later. --mmffssmmuulldd --mmnnoo--ffssmmuulldd With --mmffssmmuulldd, GCC generates code that takes advantage of the Floating-point Multiply Single to Double (FsMULd) instruction. The default is --mmffssmmuulldd when targeting a CPU supporting the architec- ture versions V8 or V9 with FPU except --mmccppuu==lleeoonn. --mmppooppcc --mmnnoo--ppooppcc With --mmppooppcc, GCC generates code that takes advantage of the Ultra- SPARC Population Count instruction. The default is --mmppooppcc when targeting a CPU that supports such an instruction, such as Nia- gara-2 and later. --mmssuubbxxcc --mmnnoo--ssuubbxxcc With --mmssuubbxxcc, GCC generates code that takes advantage of the Ultra- SPARC Subtract-Extended-with-Carry instruction. The default is --mmssuubbxxcc when targeting a CPU that supports such an instruction, such as Niagara-7 and later. --mmffiixx--aatt669977ff Enable the documented workaround for the single erratum of the At- mel AT697F processor (which corresponds to erratum #13 of the AT697E processor). --mmffiixx--uutt669999 Enable the documented workarounds for the floating-point errata and the data cache nullify errata of the UT699 processor. --mmffiixx--uutt770000 Enable the documented workaround for the back-to-back store errata of the UT699E/UT700 processor. --mmffiixx--ggrr771122rrcc Enable the documented workaround for the back-to-back store errata of the GR712RC processor. These --mm options are supported in addition to the above on SPARC-V9 processors in 64-bit environments: --mm3322 --mm6644 Generate code for a 32-bit or 64-bit environment. The 32-bit envi- ronment sets int, long and pointer to 32 bits. The 64-bit environ- ment sets int to 32 bits and long and pointer to 64 bits. --mmccmmooddeell==_w_h_i_c_h Set the code model to one of mmeeddllooww The Medium/Low code model: 64-bit addresses, programs must be linked in the low 32 bits of memory. Programs can be stati- cally or dynamically linked. mmeeddmmiidd The Medium/Middle code model: 64-bit addresses, programs must be linked in the low 44 bits of memory, the text and data seg- ments must be less than 2GB in size and the data segment must be located within 2GB of the text segment. mmeeddaannyy The Medium/Anywhere code model: 64-bit addresses, programs may be linked anywhere in memory, the text and data segments must be less than 2GB in size and the data segment must be located within 2GB of the text segment. eemmbbmmeeddaannyy The Medium/Anywhere code model for embedded systems: 64-bit ad- dresses, the text and data segments must be less than 2GB in size, both starting anywhere in memory (determined at link time). The global register %g4 points to the base of the data segment. Programs are statically linked and PIC is not sup- ported. --mmmmeemmoorryy--mmooddeell==_m_e_m_-_m_o_d_e_l Set the memory model in force on the processor to one of ddeeffaauulltt The default memory model for the processor and operating sys- tem. rrmmoo Relaxed Memory Order ppssoo Partial Store Order ttssoo Total Store Order sscc Sequential Consistency These memory models are formally defined in Appendix D of the SPARC-V9 architecture manual, as set in the processor's "PSTATE.MM" field. --mmssttaacckk--bbiiaass --mmnnoo--ssttaacckk--bbiiaass With --mmssttaacckk--bbiiaass, GCC assumes that the stack pointer, and frame pointer if present, are offset by -2047 which must be added back when making stack frame references. This is the default in 64-bit mode. Otherwise, assume no such offset is present. _O_p_t_i_o_n_s _f_o_r _S_y_s_t_e_m _V These additional options are available on System V Release 4 for com- patibility with other compilers on those systems: --GG Create a shared object. It is recommended that --ssyymmbboolliicc or --sshhaarreedd be used instead. --QQyy Identify the versions of each tool used by the compiler, in a ".ident" assembler directive in the output. --QQnn Refrain from adding ".ident" directives to the output file (this is the default). --YYPP,,_d_i_r_s Search the directories _d_i_r_s, and no others, for libraries specified with --ll. --YYmm,,_d_i_r Look in the directory _d_i_r to find the M4 preprocessor. The assem- bler uses this option. _T_I_L_E_-_G_x _O_p_t_i_o_n_s These --mm options are supported on the TILE-Gx: --mmccmmooddeell==ssmmaallll Generate code for the small model. The distance for direct calls is limited to 500M in either direction. PC-relative addresses are 32 bits. Absolute addresses support the full address range. --mmccmmooddeell==llaarrggee Generate code for the large model. There is no limitation on call distance, pc-relative addresses, or absolute addresses. --mmccppuu==_n_a_m_e Selects the type of CPU to be targeted. Currently the only sup- ported type is ttiilleeggxx. --mm3322 --mm6644 Generate code for a 32-bit or 64-bit environment. The 32-bit envi- ronment sets int, long, and pointer to 32 bits. The 64-bit envi- ronment sets int to 32 bits and long and pointer to 64 bits. --mmbbiigg--eennddiiaann --mmlliittttllee--eennddiiaann Generate code in big/little endian mode, respectively. _T_I_L_E_P_r_o _O_p_t_i_o_n_s These --mm options are supported on the TILEPro: --mmccppuu==_n_a_m_e Selects the type of CPU to be targeted. Currently the only sup- ported type is ttiilleepprroo. --mm3322 Generate code for a 32-bit environment, which sets int, long, and pointer to 32 bits. This is the only supported behavior so the flag is essentially ignored. _V_8_5_0 _O_p_t_i_o_n_s These --mm options are defined for V850 implementations: --mmlloonngg--ccaallllss --mmnnoo--lloonngg--ccaallllss Treat all calls as being far away (near). If calls are assumed to be far away, the compiler always loads the function's address into a register, and calls indirect through the pointer. --mmnnoo--eepp --mmeepp Do not optimize (do optimize) basic blocks that use the same index pointer 4 or more times to copy pointer into the "ep" register, and use the shorter "sld" and "sst" instructions. The --mmeepp option is on by default if you optimize. --mmnnoo--pprroolloogg--ffuunnccttiioonn --mmpprroolloogg--ffuunnccttiioonn Do not use (do use) external functions to save and restore regis- ters at the prologue and epilogue of a function. The external functions are slower, but use less code space if more than one function saves the same number of registers. The --mmpprroolloogg--ffuunnccttiioonn option is on by default if you optimize. --mmssppaaccee Try to make the code as small as possible. At present, this just turns on the --mmeepp and --mmpprroolloogg--ffuunnccttiioonn options. --mmttddaa==_n Put static or global variables whose size is _n bytes or less into the tiny data area that register "ep" points to. The tiny data area can hold up to 256 bytes in total (128 bytes for byte refer- ences). --mmssddaa==_n Put static or global variables whose size is _n bytes or less into the small data area that register "gp" points to. The small data area can hold up to 64 kilobytes. --mmzzddaa==_n Put static or global variables whose size is _n bytes or less into the first 32 kilobytes of memory. --mmvv885500 Specify that the target processor is the V850. --mmvv885500ee33vv55 Specify that the target processor is the V850E3V5. The preproces- sor constant "__v850e3v5__" is defined if this option is used. --mmvv885500ee22vv44 Specify that the target processor is the V850E3V5. This is an alias for the --mmvv885500ee33vv55 option. --mmvv885500ee22vv33 Specify that the target processor is the V850E2V3. The preproces- sor constant "__v850e2v3__" is defined if this option is used. --mmvv885500ee22 Specify that the target processor is the V850E2. The preprocessor constant "__v850e2__" is defined if this option is used. --mmvv885500ee11 Specify that the target processor is the V850E1. The preprocessor constants "__v850e1__" and "__v850e__" are defined if this option is used. --mmvv885500eess Specify that the target processor is the V850ES. This is an alias for the --mmvv885500ee11 option. --mmvv885500ee Specify that the target processor is the V850E. The preprocessor constant "__v850e__" is defined if this option is used. If neither --mmvv885500 nor --mmvv885500ee nor --mmvv885500ee11 nor --mmvv885500ee22 nor --mmvv885500ee22vv33 nor --mmvv885500ee33vv55 are defined then a default target proces- sor is chosen and the relevant ____vv885500**____ preprocessor constant is defined. The preprocessor constants "__v850" and "__v851__" are always de- fined, regardless of which processor variant is the target. --mmddiissaabbllee--ccaalllltt --mmnnoo--ddiissaabbllee--ccaalllltt This option suppresses generation of the "CALLT" instruction for the v850e, v850e1, v850e2, v850e2v3 and v850e3v5 flavors of the v850 architecture. This option is enabled by default when the RH850 ABI is in use (see --mmrrhh885500--aabbii), and disabled by default when the GCC ABI is in use. If "CALLT" instructions are being generated then the C preprocessor symbol "__V850_CALLT__" is defined. --mmrreellaaxx --mmnnoo--rreellaaxx Pass on (or do not pass on) the --mmrreellaaxx command-line option to the assembler. --mmlloonngg--jjuummppss --mmnnoo--lloonngg--jjuummppss Disable (or re-enable) the generation of PC-relative jump instruc- tions. --mmssoofftt--ffllooaatt --mmhhaarrdd--ffllooaatt Disable (or re-enable) the generation of hardware floating point instructions. This option is only significant when the target ar- chitecture is VV885500EE22VV33 or higher. If hardware floating point in- structions are being generated then the C preprocessor symbol "__FPU_OK__" is defined, otherwise the symbol "__NO_FPU__" is de- fined. --mmlloooopp Enables the use of the e3v5 LOOP instruction. The use of this in- struction is not enabled by default when the e3v5 architecture is selected because its use is still experimental. --mmrrhh885500--aabbii --mmgghhss Enables support for the RH850 version of the V850 ABI. This is the default. With this version of the ABI the following rules apply: * Integer sized structures and unions are returned via a memory pointer rather than a register. * Large structures and unions (more than 8 bytes in size) are passed by value. * Functions are aligned to 16-bit boundaries. * The --mm88bbyyttee--aalliiggnn command-line option is supported. * The --mmddiissaabbllee--ccaalllltt command-line option is enabled by default. The --mmnnoo--ddiissaabbllee--ccaalllltt command-line option is not supported. When this version of the ABI is enabled the C preprocessor symbol "__V850_RH850_ABI__" is defined. --mmggcccc--aabbii Enables support for the old GCC version of the V850 ABI. With this version of the ABI the following rules apply: * Integer sized structures and unions are returned in register "r10". * Large structures and unions (more than 8 bytes in size) are passed by reference. * Functions are aligned to 32-bit boundaries, unless optimizing for size. * The --mm88bbyyttee--aalliiggnn command-line option is not supported. * The --mmddiissaabbllee--ccaalllltt command-line option is supported but not enabled by default. When this version of the ABI is enabled the C preprocessor symbol "__V850_GCC_ABI__" is defined. --mm88bbyyttee--aalliiggnn --mmnnoo--88bbyyttee--aalliiggnn Enables support for "double" and "long long" types to be aligned on 8-byte boundaries. The default is to restrict the alignment of all objects to at most 4-bytes. When --mm88bbyyttee--aalliiggnn is in effect the C preprocessor symbol "__V850_8BYTE_ALIGN__" is defined. --mmbbiigg--sswwiittcchh Generate code suitable for big switch tables. Use this option only if the assembler/linker complain about out of range branches within a switch table. --mmaapppp--rreeggss This option causes r2 and r5 to be used in the code generated by the compiler. This setting is the default. --mmnnoo--aapppp--rreeggss This option causes r2 and r5 to be treated as fixed registers. _V_A_X _O_p_t_i_o_n_s These --mm options are defined for the VAX: --mmuunniixx Do not output certain jump instructions ("aobleq" and so on) that the Unix assembler for the VAX cannot handle across long ranges. --mmggnnuu Do output those jump instructions, on the assumption that the GNU assembler is being used. --mmgg Output code for G-format floating-point numbers instead of D-for- mat. --mmllrraa --mmnnoo--llrraa Enable Local Register Allocation. This is still experimental for the VAX, so by default the compiler uses standard reload. _V_i_s_i_u_m _O_p_t_i_o_n_s --mmddeebbuugg A program which performs file I/O and is destined to run on an MCM target should be linked with this option. It causes the libraries libc.a and libdebug.a to be linked. The program should be run on the target under the control of the GDB remote debugging stub. --mmssiimm A program which performs file I/O and is destined to run on the simulator should be linked with option. This causes libraries libc.a and libsim.a to be linked. --mmffppuu --mmhhaarrdd--ffllooaatt Generate code containing floating-point instructions. This is the default. --mmnnoo--ffppuu --mmssoofftt--ffllooaatt Generate code containing library calls for floating-point. --mmssoofftt--ffllooaatt changes the calling convention in the output file; therefore, it is only useful if you compile _a_l_l of a program with this option. In particular, you need to compile _l_i_b_g_c_c_._a, the li- brary that comes with GCC, with --mmssoofftt--ffllooaatt in order for this to work. --mmccppuu==_c_p_u___t_y_p_e Set the instruction set, register set, and instruction scheduling parameters for machine type _c_p_u___t_y_p_e. Supported values for _c_p_u___t_y_p_e are mmccmm, ggrr55 and ggrr66. mmccmm is a synonym of ggrr55 present for backward compatibility. By default (unless configured otherwise), GCC generates code for the GR5 variant of the Visium architecture. With --mmccppuu==ggrr66, GCC generates code for the GR6 variant of the Vi- sium architecture. The only difference from GR5 code is that the compiler will generate block move instructions. --mmttuunnee==_c_p_u___t_y_p_e Set the instruction scheduling parameters for machine type _c_p_u___t_y_p_e, but do not set the instruction set or register set that the option --mmccppuu==_c_p_u___t_y_p_e would. --mmssvv--mmooddee Generate code for the supervisor mode, where there are no restric- tions on the access to general registers. This is the default. --mmuusseerr--mmooddee Generate code for the user mode, where the access to some general registers is forbidden: on the GR5, registers r24 to r31 cannot be accessed in this mode; on the GR6, only registers r29 to r31 are affected. _V_M_S _O_p_t_i_o_n_s These --mm options are defined for the VMS implementations: --mmvvmmss--rreettuurrnn--ccooddeess Return VMS condition codes from "main". The default is to return POSIX-style condition (e.g. error) codes. --mmddeebbuugg--mmaaiinn==_p_r_e_f_i_x Flag the first routine whose name starts with _p_r_e_f_i_x as the main routine for the debugger. --mmmmaalllloocc6644 Default to 64-bit memory allocation routines. --mmppooiinntteerr--ssiizzee==_s_i_z_e Set the default size of pointers. Possible options for _s_i_z_e are 3322 or sshhoorrtt for 32 bit pointers, 6644 or lloonngg for 64 bit pointers, and nnoo for supporting only 32 bit pointers. The later option disables "pragma pointer_size". _V_x_W_o_r_k_s _O_p_t_i_o_n_s The options in this section are defined for all VxWorks targets. Op- tions specific to the target hardware are listed with the other options for that target. --mmrrttpp GCC can generate code for both VxWorks kernels and real time pro- cesses (RTPs). This option switches from the former to the latter. It also defines the preprocessor macro "__RTP__". --nnoonn--ssttaattiicc Link an RTP executable against shared libraries rather than static libraries. The options --ssttaattiicc and --sshhaarreedd can also be used for RTPs; --ssttaattiicc is the default. --BBssttaattiicc --BBddyynnaammiicc These options are passed down to the linker. They are defined for compatibility with Diab. --XXbbiinndd--llaazzyy Enable lazy binding of function calls. This option is equivalent to --WWll,,--zz,,nnooww and is defined for compatibility with Diab. --XXbbiinndd--nnooww Disable lazy binding of function calls. This option is the default and is defined for compatibility with Diab. _x_8_6 _O_p_t_i_o_n_s These --mm options are defined for the x86 family of computers. --mmaarrcchh==_c_p_u_-_t_y_p_e Generate instructions for the machine type _c_p_u_-_t_y_p_e. In contrast to --mmttuunnee==_c_p_u_-_t_y_p_e, which merely tunes the generated code for the specified _c_p_u_-_t_y_p_e, --mmaarrcchh==_c_p_u_-_t_y_p_e allows GCC to generate code that may not run at all on processors other than the one indicated. Specifying --mmaarrcchh==_c_p_u_-_t_y_p_e implies --mmttuunnee==_c_p_u_-_t_y_p_e, except where noted otherwise. The choices for _c_p_u_-_t_y_p_e are: nnaattiivvee This selects the CPU to generate code for at compilation time by determining the processor type of the compiling machine. Using --mmaarrcchh==nnaattiivvee enables all instruction subsets supported by the local machine (hence the result might not run on differ- ent machines). Using --mmttuunnee==nnaattiivvee produces code optimized for the local machine under the constraints of the selected in- struction set. xx8866--6644 A generic CPU with 64-bit extensions. xx8866--6644--vv22 xx8866--6644--vv33 xx8866--6644--vv44 These choices for _c_p_u_-_t_y_p_e select the corresponding micro-ar- chitecture level from the x86-64 psABI. On ABIs other than the x86-64 psABI they select the same CPU features as the x86-64 psABI documents for the particular micro-architecture level. Since these _c_p_u_-_t_y_p_e values do not have a corresponding --mmttuunnee setting, using --mmaarrcchh with these values enables generic tuning. Specific tuning can be enabled using the --mmttuunnee==_o_t_h_e_r_-_c_p_u_-_t_y_p_e option with an appropriate _o_t_h_e_r_-_c_p_u_-_t_y_p_e value. ii338866 Original Intel i386 CPU. ii448866 Intel i486 CPU. (No scheduling is implemented for this chip.) ii558866 ppeennttiiuumm Intel Pentium CPU with no MMX support. llaakkeemmoonntt Intel Lakemont MCU, based on Intel Pentium CPU. ppeennttiiuumm--mmmmxx Intel Pentium MMX CPU, based on Pentium core with MMX instruc- tion set support. ppeennttiiuummpprroo Intel Pentium Pro CPU. ii668866 When used with --mmaarrcchh, the Pentium Pro instruction set is used, so the code runs on all i686 family chips. When used with --mmttuunnee, it has the same meaning as ggeenneerriicc. ppeennttiiuumm22 Intel Pentium II CPU, based on Pentium Pro core with MMX and FXSR instruction set support. ppeennttiiuumm33 ppeennttiiuumm33mm Intel Pentium III CPU, based on Pentium Pro core with MMX, FXSR and SSE instruction set support. ppeennttiiuumm--mm Intel Pentium M; low-power version of Intel Pentium III CPU with MMX, SSE, SSE2 and FXSR instruction set support. Used by Centrino notebooks. ppeennttiiuumm44 ppeennttiiuumm44mm Intel Pentium 4 CPU with MMX, SSE, SSE2 and FXSR instruction set support. pprreessccootttt Improved version of Intel Pentium 4 CPU with MMX, SSE, SSE2, SSE3 and FXSR instruction set support. nnooccoonnaa Improved version of Intel Pentium 4 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3 and FXSR instruction set support. ccoorree22 Intel Core 2 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3, CX16, SAHF and FXSR instruction set support. nneehhaalleemm Intel Nehalem CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF and FXSR instruction set support. wweessttmmeerree Intel Westmere CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR and PCLMUL instruction set support. ssaannddyybbrriiddggee Intel Sandy Bridge CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE and PCLMUL instruction set support. iivvyybbrriiddggee Intel Ivy Bridge CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND and F16C instruction set sup- port. hhaasswweellll Intel Haswell CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE and HLE instruction set support. bbrrooaaddwweellll Intel Broadwell CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX and PREFETCHW instruction set support. sskkyyllaakkee Intel Skylake CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES, CLFLUSHOPT, XSAVEC, XSAVES and SGX instruction set support. bboonnnneellll Intel Bonnell CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3 and SSSE3 instruction set support. ssiillvveerrmmoonntt Intel Silvermont CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, PCLMUL, PREFETCHW and RDRND instruction set support. ggoollddmmoonntt Intel Goldmont CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, PCLMUL, PREFETCHW, RDRND, AES, SHA, RDSEED, XSAVE, XSAVEC, XSAVES, XSAVEOPT, CLFLUSHOPT and FSGSBASE instruction set sup- port. ggoollddmmoonntt--pplluuss Intel Goldmont Plus CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, PCLMUL, PREFETCHW, RDRND, AES, SHA, RDSEED, XSAVE, XSAVEC, XSAVES, XSAVEOPT, CLFLUSHOPT, FSGSBASE, PTWRITE, RDPID and SGX instruction set support. ttrreemmoonntt Intel Tremont CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, PCLMUL, PREFETCHW, RDRND, AES, SHA, RDSEED, XSAVE, XSAVEC, XSAVES, XSAVEOPT, CLFLUSHOPT, FSGSBASE, PTWRITE, RDPID, SGX, CLWB, GFNI-SSE, MOVDIRI, MOVDIR64B, CLDEMOTE and WAITPKG in- struction set support. kknnll Intel Knight's Landing CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AVX512PF, AVX512ER, AVX512F, AVX512CD and PREFETCHWT1 instruc- tion set support. kknnmm Intel Knights Mill CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AVX512PF, AVX512ER, AVX512F, AVX512CD and PREFETCHWT1, AVX5124VNNIW, AVX5124FMAPS and AVX512VPOPCNTDQ instruction set support. sskkyyllaakkee--aavvxx551122 Intel Skylake Server CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES, CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, CLWB, AVX512VL, AVX512BW, AVX512DQ and AVX512CD instruction set support. ccaannnnoonnllaakkee Intel Cannonlake Server CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES, CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, AVX512VL, AVX512BW, AVX512DQ, AVX512CD, PKU, AVX512VBMI, AVX512IFMA and SHA in- struction set support. iicceellaakkee--cclliieenntt Intel Icelake Client CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES, CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, AVX512VL, AVX512BW, AVX512DQ, AVX512CD, PKU, AVX512VBMI, AVX512IFMA, SHA, AVX512VNNI, GFNI, VAES, AVX512VBMI2 , VPCLMULQDQ, AVX512BITALG, RDPID and AVX512VPOPCNTDQ instruction set support. iicceellaakkee--sseerrvveerr Intel Icelake Server CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES, CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, AVX512VL, AVX512BW, AVX512DQ, AVX512CD, PKU, AVX512VBMI, AVX512IFMA, SHA, AVX512VNNI, GFNI, VAES, AVX512VBMI2 , VPCLMULQDQ, AVX512BITALG, RDPID, AVX512VPOPCNTDQ, PCONFIG, WBNOINVD and CLWB instruction set support. ccaassccaaddeellaakkee Intel Cascadelake CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES, CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, CLWB, AVX512VL, AVX512BW, AVX512DQ, AVX512CD and AVX512VNNI instruction set support. ccooooppeerrllaakkee Intel cooperlake CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES, CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, CLWB, AVX512VL, AVX512BW, AVX512DQ, AVX512CD, AVX512VNNI and AVX512BF16 in- struction set support. ttiiggeerrllaakkee Intel Tigerlake CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES, CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, AVX512VL, AVX512BW, AVX512DQ, AVX512CD PKU, AVX512VBMI, AVX512IFMA, SHA, AVX512VNNI, GFNI, VAES, AVX512VBMI2, VPCLMULQDQ, AVX512BITALG, RDPID, AVX512VPOPCNTDQ, MOVDIRI, MOVDIR64B, CLWB, AVX512VP2IN- TERSECT and KEYLOCKER instruction set support. ssaapppphhiirreerraappiiddss Intel sapphirerapids CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES, CLFLUSHOPT, XSAVEC, XSAVES, SGX, AVX512F, AVX512VL, AVX512BW, AVX512DQ, AVX512CD, PKU, AVX512VBMI, AVX512IFMA, SHA, AVX512VNNI, GFNI, VAES, AVX512VBMI2 VPCLMULQDQ, AVX512BITALG, RDPID, AVX512VPOPCNTDQ, PCONFIG, WBNOINVD, CLWB, MOVDIRI, MOVDIR64B, AVX512VP2INTERSECT, ENQCMD, CLDEMOTE, PTWRITE, WAIT- PKG, SERIALIZE, TSXLDTRK, UINTR, AMX-BF16, AMX-TILE, AMX-INT8, AVX-VNNI, AVX512FP16 and AVX512BF16 instruction set support. aallddeerrllaakkee Intel Alderlake CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, AES, PREFETCHW, PCLMUL, RDRND, XSAVE, XSAVEC, XSAVES, XSAVEOPT, FSGSBASE, PTWRITE, RDPID, SGX, GFNI-SSE, CLWB, MOVDIRI, MOVDIR64B, CLDE- MOTE, WAITPKG, ADCX, AVX, AVX2, BMI, BMI2, F16C, FMA, LZCNT, PCONFIG, PKU, VAES, VPCLMULQDQ, SERIALIZE, HRESET, KL, WIDEKL and AVX-VNNI instruction set support. rroocckkeettllaakkee Intel Rocketlake CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3 , SSE4.1, SSE4.2, POPCNT, CX16, SAHF, FXSR, AVX, XSAVE, PCLMUL, FSGSBASE, RDRND, F16C, AVX2, BMI, BMI2, LZCNT, FMA, MOVBE, HLE, RDSEED, ADCX, PREFETCHW, AES, CLFLUSHOPT, XSAVEC, XSAVES, AVX512F, AVX512VL, AVX512BW, AVX512DQ, AVX512CD PKU, AVX512VBMI, AVX512IFMA, SHA, AVX512VNNI, GFNI, VAES, AVX512VBMI2, VPCLMULQDQ, AVX512BITALG, RDPID and AVX512VPOPCNTDQ instruction set support. kk66 AMD K6 CPU with MMX instruction set support. kk66--22 kk66--33 Improved versions of AMD K6 CPU with MMX and 3DNow! instruction set support. aatthhlloonn aatthhlloonn--ttbbiirrdd AMD Athlon CPU with MMX, 3dNOW!, enhanced 3DNow! and SSE prefetch instructions support. aatthhlloonn--44 aatthhlloonn--xxpp aatthhlloonn--mmpp Improved AMD Athlon CPU with MMX, 3DNow!, enhanced 3DNow! and full SSE instruction set support. kk88 oopptteerroonn aatthhlloonn6644 aatthhlloonn--ffxx Processors based on the AMD K8 core with x86-64 instruction set support, including the AMD Opteron, Athlon 64, and Athlon 64 FX processors. (This supersets MMX, SSE, SSE2, 3DNow!, enhanced 3DNow! and 64-bit instruction set extensions.) kk88--ssssee33 oopptteerroonn--ssssee33 aatthhlloonn6644--ssssee33 Improved versions of AMD K8 cores with SSE3 instruction set support. aammddffaamm1100 bbaarrcceelloonnaa CPUs based on AMD Family 10h cores with x86-64 instruction set support. (This supersets MMX, SSE, SSE2, SSE3, SSE4A, 3DNow!, enhanced 3DNow!, ABM and 64-bit instruction set extensions.) bbddvveerr11 CPUs based on AMD Family 15h cores with x86-64 instruction set support. (This supersets FMA4, AVX, XOP, LWP, AES, PCLMUL, CX16, MMX, SSE, SSE2, SSE3, SSE4A, SSSE3, SSE4.1, SSE4.2, ABM and 64-bit instruction set extensions.) bbddvveerr22 AMD Family 15h core based CPUs with x86-64 instruction set sup- port. (This supersets BMI, TBM, F16C, FMA, FMA4, AVX, XOP, LWP, AES, PCLMUL, CX16, MMX, SSE, SSE2, SSE3, SSE4A, SSSE3, SSE4.1, SSE4.2, ABM and 64-bit instruction set extensions.) bbddvveerr33 AMD Family 15h core based CPUs with x86-64 instruction set sup- port. (This supersets BMI, TBM, F16C, FMA, FMA4, FSGSBASE, AVX, XOP, LWP, AES, PCLMUL, CX16, MMX, SSE, SSE2, SSE3, SSE4A, SSSE3, SSE4.1, SSE4.2, ABM and 64-bit instruction set exten- sions.) bbddvveerr44 AMD Family 15h core based CPUs with x86-64 instruction set sup- port. (This supersets BMI, BMI2, TBM, F16C, FMA, FMA4, FSGS- BASE, AVX, AVX2, XOP, LWP, AES, PCLMUL, CX16, MOVBE, MMX, SSE, SSE2, SSE3, SSE4A, SSSE3, SSE4.1, SSE4.2, ABM and 64-bit in- struction set extensions.) zznnvveerr11 AMD Family 17h core based CPUs with x86-64 instruction set sup- port. (This supersets BMI, BMI2, F16C, FMA, FSGSBASE, AVX, AVX2, ADCX, RDSEED, MWAITX, SHA, CLZERO, AES, PCLMUL, CX16, MOVBE, MMX, SSE, SSE2, SSE3, SSE4A, SSSE3, SSE4.1, SSE4.2, ABM, XSAVEC, XSAVES, CLFLUSHOPT, POPCNT, and 64-bit instruction set extensions.) zznnvveerr22 AMD Family 17h core based CPUs with x86-64 instruction set sup- port. (This supersets BMI, BMI2, CLWB, F16C, FMA, FSGSBASE, AVX, AVX2, ADCX, RDSEED, MWAITX, SHA, CLZERO, AES, PCLMUL, CX16, MOVBE, MMX, SSE, SSE2, SSE3, SSE4A, SSSE3, SSE4.1, SSE4.2, ABM, XSAVEC, XSAVES, CLFLUSHOPT, POPCNT, RDPID, WB- NOINVD, and 64-bit instruction set extensions.) zznnvveerr33 AMD Family 19h core based CPUs with x86-64 instruction set sup- port. (This supersets BMI, BMI2, CLWB, F16C, FMA, FSGSBASE, AVX, AVX2, ADCX, RDSEED, MWAITX, SHA, CLZERO, AES, PCLMUL, CX16, MOVBE, MMX, SSE, SSE2, SSE3, SSE4A, SSSE3, SSE4.1, SSE4.2, ABM, XSAVEC, XSAVES, CLFLUSHOPT, POPCNT, RDPID, WB- NOINVD, PKU, VPCLMULQDQ, VAES, and 64-bit instruction set ex- tensions.) bbttvveerr11 CPUs based on AMD Family 14h cores with x86-64 instruction set support. (This supersets MMX, SSE, SSE2, SSE3, SSSE3, SSE4A, CX16, ABM and 64-bit instruction set extensions.) bbttvveerr22 CPUs based on AMD Family 16h cores with x86-64 instruction set support. This includes MOVBE, F16C, BMI, AVX, PCLMUL, AES, SSE4.2, SSE4.1, CX16, ABM, SSE4A, SSSE3, SSE3, SSE2, SSE, MMX and 64-bit instruction set extensions. wwiinncchhiipp--cc66 IDT WinChip C6 CPU, dealt in same way as i486 with additional MMX instruction set support. wwiinncchhiipp22 IDT WinChip 2 CPU, dealt in same way as i486 with additional MMX and 3DNow! instruction set support. cc33 VIA C3 CPU with MMX and 3DNow! instruction set support. (No scheduling is implemented for this chip.) cc33--22 VIA C3-2 (Nehemiah/C5XL) CPU with MMX and SSE instruction set support. (No scheduling is implemented for this chip.) cc77 VIA C7 (Esther) CPU with MMX, SSE, SSE2 and SSE3 instruction set support. (No scheduling is implemented for this chip.) ssaammuueell--22 VIA Eden Samuel 2 CPU with MMX and 3DNow! instruction set sup- port. (No scheduling is implemented for this chip.) nneehheemmiiaahh VIA Eden Nehemiah CPU with MMX and SSE instruction set support. (No scheduling is implemented for this chip.) eesstthheerr VIA Eden Esther CPU with MMX, SSE, SSE2 and SSE3 instruction set support. (No scheduling is implemented for this chip.) eeddeenn--xx22 VIA Eden X2 CPU with x86-64, MMX, SSE, SSE2 and SSE3 instruc- tion set support. (No scheduling is implemented for this chip.) eeddeenn--xx44 VIA Eden X4 CPU with x86-64, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, AVX and AVX2 instruction set support. (No scheduling is implemented for this chip.) nnaannoo Generic VIA Nano CPU with x86-64, MMX, SSE, SSE2, SSE3 and SSSE3 instruction set support. (No scheduling is implemented for this chip.) nnaannoo--11000000 VIA Nano 1xxx CPU with x86-64, MMX, SSE, SSE2, SSE3 and SSSE3 instruction set support. (No scheduling is implemented for this chip.) nnaannoo--22000000 VIA Nano 2xxx CPU with x86-64, MMX, SSE, SSE2, SSE3 and SSSE3 instruction set support. (No scheduling is implemented for this chip.) nnaannoo--33000000 VIA Nano 3xxx CPU with x86-64, MMX, SSE, SSE2, SSE3, SSSE3 and SSE4.1 instruction set support. (No scheduling is implemented for this chip.) nnaannoo--xx22 VIA Nano Dual Core CPU with x86-64, MMX, SSE, SSE2, SSE3, SSSE3 and SSE4.1 instruction set support. (No scheduling is imple- mented for this chip.) nnaannoo--xx44 VIA Nano Quad Core CPU with x86-64, MMX, SSE, SSE2, SSE3, SSSE3 and SSE4.1 instruction set support. (No scheduling is imple- mented for this chip.) ggeeooddee AMD Geode embedded processor with MMX and 3DNow! instruction set support. --mmttuunnee==_c_p_u_-_t_y_p_e Tune to _c_p_u_-_t_y_p_e everything applicable about the generated code, except for the ABI and the set of available instructions. While picking a specific _c_p_u_-_t_y_p_e schedules things appropriately for that particular chip, the compiler does not generate any code that can- not run on the default machine type unless you use a --mmaarrcchh==_c_p_u_- _t_y_p_e option. For example, if GCC is configured for i686-pc-linux-gnu then --mmttuunnee==ppeennttiiuumm44 generates code that is tuned for Pentium 4 but still runs on i686 machines. The choices for _c_p_u_-_t_y_p_e are the same as for --mmaarrcchh. In addition, --mmttuunnee supports 2 extra choices for _c_p_u_-_t_y_p_e: ggeenneerriicc Produce code optimized for the most common IA32/AMD64/EM64T processors. If you know the CPU on which your code will run, then you should use the corresponding --mmttuunnee or --mmaarrcchh option instead of --mmttuunnee==ggeenneerriicc. But, if you do not know exactly what CPU users of your application will have, then you should use this option. As new processors are deployed in the marketplace, the behavior of this option will change. Therefore, if you upgrade to a newer version of GCC, code generation controlled by this option will change to reflect the processors that are most common at the time that version of GCC is released. There is no --mmaarrcchh==ggeenneerriicc option because --mmaarrcchh indicates the instruction set the compiler can use, and there is no generic instruction set applicable to all processors. In contrast, --mmttuunnee indicates the processor (or, in this case, collection of processors) for which the code is optimized. iinntteell Produce code optimized for the most current Intel processors, which are Haswell and Silvermont for this version of GCC. If you know the CPU on which your code will run, then you should use the corresponding --mmttuunnee or --mmaarrcchh option instead of --mmttuunnee==iinntteell. But, if you want your application performs bet- ter on both Haswell and Silvermont, then you should use this option. As new Intel processors are deployed in the marketplace, the behavior of this option will change. Therefore, if you upgrade to a newer version of GCC, code generation controlled by this option will change to reflect the most current Intel processors at the time that version of GCC is released. There is no --mmaarrcchh==iinntteell option because --mmaarrcchh indicates the instruction set the compiler can use, and there is no common instruction set applicable to all processors. In contrast, --mmttuunnee indicates the processor (or, in this case, collection of processors) for which the code is optimized. --mmccppuu==_c_p_u_-_t_y_p_e A deprecated synonym for --mmttuunnee. --mmffppmmaatthh==_u_n_i_t Generate floating-point arithmetic for selected unit _u_n_i_t. The choices for _u_n_i_t are: 338877 Use the standard 387 floating-point coprocessor present on the majority of chips and emulated otherwise. Code compiled with this option runs almost everywhere. The temporary results are computed in 80-bit precision instead of the precision specified by the type, resulting in slightly different results compared to most of other chips. See --ffffllooaatt--ssttoorree for more detailed description. This is the default choice for non-Darwin x86-32 targets. ssssee Use scalar floating-point instructions present in the SSE in- struction set. This instruction set is supported by Pentium III and newer chips, and in the AMD line by Athlon-4, Athlon XP and Athlon MP chips. The earlier version of the SSE instruc- tion set supports only single-precision arithmetic, thus the double and extended-precision arithmetic are still done using 387. A later version, present only in Pentium 4 and AMD x86-64 chips, supports double-precision arithmetic too. For the x86-32 compiler, you must use --mmaarrcchh==_c_p_u_-_t_y_p_e, --mmssssee or --mmssssee22 switches to enable SSE extensions and make this option effective. For the x86-64 compiler, these extensions are en- abled by default. The resulting code should be considerably faster in the major- ity of cases and avoid the numerical instability problems of 387 code, but may break some existing code that expects tempo- raries to be 80 bits. This is the default choice for the x86-64 compiler, Darwin x86-32 targets, and the default choice for x86-32 targets with the SSE2 instruction set when --ffffaasstt--mmaatthh is enabled. ssssee,,338877 ssssee++338877 bbootthh Attempt to utilize both instruction sets at once. This effec- tively doubles the amount of available registers, and on chips with separate execution units for 387 and SSE the execution re- sources too. Use this option with care, as it is still experi- mental, because the GCC register allocator does not model sepa- rate functional units well, resulting in unstable performance. --mmaassmm==_d_i_a_l_e_c_t Output assembly instructions using selected _d_i_a_l_e_c_t. Also affects which dialect is used for basic "asm" and extended "asm". Supported choices (in dialect order) are aatttt or iinntteell. The default is aatttt. Darwin does not support iinntteell. --mmiieeeeee--ffpp --mmnnoo--iieeeeee--ffpp Control whether or not the compiler uses IEEE floating-point com- parisons. These correctly handle the case where the result of a comparison is unordered. --mm8800338877 --mmhhaarrdd--ffllooaatt Generate output containing 80387 instructions for floating point. --mmnnoo--8800338877 --mmssoofftt--ffllooaatt Generate output containing library calls for floating point. WWaarrnniinngg:: the requisite libraries are not part of GCC. Normally the facilities of the machine's usual C compiler are used, but this cannot be done directly in cross-compilation. You must make your own arrangements to provide suitable library functions for cross-compilation. On machines where a function returns floating-point results in the 80387 register stack, some floating-point opcodes may be emitted even if --mmssoofftt--ffllooaatt is used. --mmnnoo--ffpp--rreett--iinn--338877 Do not use the FPU registers for return values of functions. The usual calling convention has functions return values of types "float" and "double" in an FPU register, even if there is no FPU. The idea is that the operating system should emulate an FPU. The option --mmnnoo--ffpp--rreett--iinn--338877 causes such values to be returned in ordinary CPU registers instead. --mmnnoo--ffaannccyy--mmaatthh--338877 Some 387 emulators do not support the "sin", "cos" and "sqrt" in- structions for the 387. Specify this option to avoid generating those instructions. This option is overridden when --mmaarrcchh indi- cates that the target CPU always has an FPU and so the instruction does not need emulation. These instructions are not generated un- less you also use the --ffuunnssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss switch. --mmaalliiggnn--ddoouubbllee --mmnnoo--aalliiggnn--ddoouubbllee Control whether GCC aligns "double", "long double", and "long long" variables on a two-word boundary or a one-word boundary. Aligning "double" variables on a two-word boundary produces code that runs somewhat faster on a Pentium at the expense of more memory. On x86-64, --mmaalliiggnn--ddoouubbllee is enabled by default. WWaarrnniinngg:: if you use the --mmaalliiggnn--ddoouubbllee switch, structures contain- ing the above types are aligned differently than the published ap- plication binary interface specifications for the x86-32 and are not binary compatible with structures in code compiled without that switch. --mm9966bbiitt--lloonngg--ddoouubbllee --mm112288bbiitt--lloonngg--ddoouubbllee These switches control the size of "long double" type. The x86-32 application binary interface specifies the size to be 96 bits, so --mm9966bbiitt--lloonngg--ddoouubbllee is the default in 32-bit mode. Modern architectures (Pentium and newer) prefer "long double" to be aligned to an 8- or 16-byte boundary. In arrays or structures con- forming to the ABI, this is not possible. So specifying --mm112288bbiitt--lloonngg--ddoouubbllee aligns "long double" to a 16-byte boundary by padding the "long double" with an additional 32-bit zero. In the x86-64 compiler, --mm112288bbiitt--lloonngg--ddoouubbllee is the default choice as its ABI specifies that "long double" is aligned on 16-byte boundary. Notice that neither of these options enable any extra precision over the x87 standard of 80 bits for a "long double". WWaarrnniinngg:: if you override the default value for your target ABI, this changes the size of structures and arrays containing "long double" variables, as well as modifying the function calling con- vention for functions taking "long double". Hence they are not bi- nary-compatible with code compiled without that switch. --mmlloonngg--ddoouubbllee--6644 --mmlloonngg--ddoouubbllee--8800 --mmlloonngg--ddoouubbllee--112288 These switches control the size of "long double" type. A size of 64 bits makes the "long double" type equivalent to the "double" type. This is the default for 32-bit Bionic C library. A size of 128 bits makes the "long double" type equivalent to the "__float128" type. This is the default for 64-bit Bionic C library. WWaarrnniinngg:: if you override the default value for your target ABI, this changes the size of structures and arrays containing "long double" variables, as well as modifying the function calling con- vention for functions taking "long double". Hence they are not bi- nary-compatible with code compiled without that switch. --mmaalliiggnn--ddaattaa==_t_y_p_e Control how GCC aligns variables. Supported values for _t_y_p_e are ccoommppaatt uses increased alignment value compatible uses GCC 4.8 and earlier, aabbii uses alignment value as specified by the psABI, and ccaacchheelliinnee uses increased alignment value to match the cache line size. ccoommppaatt is the default. --mmllaarrggee--ddaattaa--tthhrreesshhoolldd==_t_h_r_e_s_h_o_l_d When --mmccmmooddeell==mmeeddiiuumm is specified, data objects larger than _t_h_r_e_s_h_- _o_l_d are placed in the large data section. This value must be the same across all objects linked into the binary, and defaults to 65535. --mmrrttdd Use a different function-calling convention, in which functions that take a fixed number of arguments return with the "ret _n_u_m_" in- struction, which pops their arguments while returning. This saves one instruction in the caller since there is no need to pop the ar- guments there. You can specify that an individual function is called with this calling sequence with the function attribute "stdcall". You can also override the --mmrrttdd option by using the function attribute "cdecl". WWaarrnniinngg:: this calling convention is incompatible with the one nor- mally used on Unix, so you cannot use it if you need to call li- braries compiled with the Unix compiler. Also, you must provide function prototypes for all functions that take variable numbers of arguments (including "printf"); otherwise incorrect code is generated for calls to those functions. In addition, seriously incorrect code results if you call a func- tion with too many arguments. (Normally, extra arguments are harm- lessly ignored.) --mmrreeggppaarrmm==_n_u_m Control how many registers are used to pass integer arguments. By default, no registers are used to pass arguments, and at most 3 registers can be used. You can control this behavior for a spe- cific function by using the function attribute "regparm". WWaarrnniinngg:: if you use this switch, and _n_u_m is nonzero, then you must build all modules with the same value, including any libraries. This includes the system libraries and startup modules. --mmsssseerreeggppaarrmm Use SSE register passing conventions for float and double arguments and return values. You can control this behavior for a specific function by using the function attribute "sseregparm". WWaarrnniinngg:: if you use this switch then you must build all modules with the same value, including any libraries. This includes the system libraries and startup modules. --mmvveecctt88--rreett--iinn--mmeemm Return 8-byte vectors in memory instead of MMX registers. This is the default on VxWorks to match the ABI of the Sun Studio compilers until version 12. _O_n_l_y use this option if you need to remain com- patible with existing code produced by those previous compiler ver- sions or older versions of GCC. --mmppcc3322 --mmppcc6644 --mmppcc8800 Set 80387 floating-point precision to 32, 64 or 80 bits. When --mmppcc3322 is specified, the significands of results of floating-point operations are rounded to 24 bits (single precision); --mmppcc6644 rounds the significands of results of floating-point operations to 53 bits (double precision) and --mmppcc8800 rounds the significands of results of floating-point operations to 64 bits (extended double precision), which is the default. When this option is used, floating-point op- erations in higher precisions are not available to the programmer without setting the FPU control word explicitly. Setting the rounding of floating-point operations to less than the default 80 bits can speed some programs by 2% or more. Note that some mathematical libraries assume that extended-precision (80-bit) floating-point operations are enabled by default; routines in such libraries could suffer significant loss of accuracy, typically through so-called "catastrophic cancellation", when this option is used to set the precision to less than extended precision. --mmssttaacckkrreeaalliiggnn Realign the stack at entry. On the x86, the --mmssttaacckkrreeaalliiggnn option generates an alternate prologue and epilogue that realigns the run- time stack if necessary. This supports mixing legacy codes that keep 4-byte stack alignment with modern codes that keep 16-byte stack alignment for SSE compatibility. See also the attribute "force_align_arg_pointer", applicable to individual functions. --mmpprreeffeerrrreedd--ssttaacckk--bboouunnddaarryy==_n_u_m Attempt to keep the stack boundary aligned to a 2 raised to _n_u_m byte boundary. If --mmpprreeffeerrrreedd--ssttaacckk--bboouunnddaarryy is not specified, the default is 4 (16 bytes or 128 bits). WWaarrnniinngg:: When generating code for the x86-64 architecture with SSE extensions disabled, --mmpprreeffeerrrreedd--ssttaacckk--bboouunnddaarryy==33 can be used to keep the stack boundary aligned to 8 byte boundary. Since x86-64 ABI require 16 byte stack alignment, this is ABI incompatible and intended to be used in controlled environment where stack space is important limitation. This option leads to wrong code when func- tions compiled with 16 byte stack alignment (such as functions from a standard library) are called with misaligned stack. In this case, SSE instructions may lead to misaligned memory access traps. In addition, variable arguments are handled incorrectly for 16 byte aligned objects (including x87 long double and __int128), leading to wrong results. You must build all modules with --mmpprree-- ffeerrrreedd--ssttaacckk--bboouunnddaarryy==33, including any libraries. This includes the system libraries and startup modules. --mmiinnccoommiinngg--ssttaacckk--bboouunnddaarryy==_n_u_m Assume the incoming stack is aligned to a 2 raised to _n_u_m byte boundary. If --mmiinnccoommiinngg--ssttaacckk--bboouunnddaarryy is not specified, the one specified by --mmpprreeffeerrrreedd--ssttaacckk--bboouunnddaarryy is used. On Pentium and Pentium Pro, "double" and "long double" values should be aligned to an 8-byte boundary (see --mmaalliiggnn--ddoouubbllee) or suffer significant run time performance penalties. On Pentium III, the Streaming SIMD Extension (SSE) data type "__m128" may not work properly if it is not 16-byte aligned. To ensure proper alignment of this values on the stack, the stack boundary must be as aligned as that required by any value stored on the stack. Further, every function must be generated such that it keeps the stack aligned. Thus calling a function compiled with a higher preferred stack boundary from a function compiled with a lower preferred stack boundary most likely misaligns the stack. It is recommended that libraries that use callbacks always use the de- fault setting. This extra alignment does consume extra stack space, and generally increases code size. Code that is sensitive to stack space usage, such as embedded systems and operating system kernels, may want to reduce the preferred alignment to --mmpprreeffeerrrreedd--ssttaacckk--bboouunnddaarryy==22. --mmmmmmxx --mmssssee --mmssssee22 --mmssssee33 --mmssssssee33 --mmssssee44 --mmssssee44aa --mmssssee44..11 --mmssssee44..22 --mmaavvxx --mmaavvxx22 --mmaavvxx551122ff --mmaavvxx551122ppff --mmaavvxx551122eerr --mmaavvxx551122ccdd --mmaavvxx551122vvll --mmaavvxx551122bbww --mmaavvxx551122ddqq --mmaavvxx551122iiffmmaa --mmaavvxx551122vvbbmmii --mmsshhaa --mmaaeess --mmppccllmmuull --mmccllfflluusshhoopptt --mmccllwwbb --mmffssggssbbaassee --mmppttwwrriittee --mmrrddrrnndd --mmff1166cc --mmffmmaa --mmppccoonnffiigg --mmwwbbnnooiinnvvdd --mmffmmaa44 --mmpprrffcchhww --mmrrddppiidd --mmpprreeffeettcchhwwtt11 --mmrrddsseeeedd --mmssggxx --mmxxoopp --mmllwwpp --mm33ddnnooww --mm33ddnnoowwaa --mmppooppccnntt --mmaabbmm --mmaaddxx --mmbbmmii --mmbbmmii22 --mmllzzccnntt --mmffxxssrr --mmxxssaavvee --mmxxssaavveeoopptt --mmxxssaavveecc --mmxxssaavveess --mmrrttmm --mmhhllee --mmttbbmm --mmmmwwaaiittxx --mmccllzzeerroo --mmppkkuu --mmaavvxx551122vvbbmmii22 --mmaavvxx551122bbff1166 --mmaavvxx551122ffpp1166 --mmggffnnii --mmvvaaeess --mmwwaaiittppkkgg --mmvvppccllmmuullqqddqq --mmaavvxx551122bbiittaallgg --mmmmoovvddiirrii --mmmmoovvddiirr6644bb --mmeennqqccmmdd --mmuuiinnttrr --mmttssxxllddttrrkk --mmaavvxx551122vvppooppccnnttddqq --mmaavvxx551122vvpp22iinntteerrsseecctt --mmaavvxx55112244ffmmaappss --mmaavvxx551122vvnnnnii --mmaavvxxvvnnnnii --mmaavvxx55112244vvnnnniiww --mmccllddeemmoottee --mmsseerriiaalliizzee --mmaammxx--ttiillee --mmaammxx--iinntt88 --mmaammxx--bbff1166 --mmhhrreesseett --mmkkll --mmwwiiddeekkll These switches enable the use of instructions in the MMX, SSE, SSE2, SSE3, SSSE3, SSE4, SSE4A, SSE4.1, SSE4.2, AVX, AVX2, AVX512F, AVX512PF, AVX512ER, AVX512CD, AVX512VL, AVX512BW, AVX512DQ, AVX512IFMA, AVX512VBMI, SHA, AES, PCLMUL, CLFLUSHOPT, CLWB, FSGS- BASE, PTWRITE, RDRND, F16C, FMA, PCONFIG, WBNOINVD, FMA4, PREFETCHW, RDPID, PREFETCHWT1, RDSEED, SGX, XOP, LWP, 3DNow!, en- hanced 3DNow!, POPCNT, ABM, ADX, BMI, BMI2, LZCNT, FXSR, XSAVE, XSAVEOPT, XSAVEC, XSAVES, RTM, HLE, TBM, MWAITX, CLZERO, PKU, AVX512VBMI2, GFNI, VAES, WAITPKG, VPCLMULQDQ, AVX512BITALG, MOVDIRI, MOVDIR64B, AVX512BF16, ENQCMD, AVX512VPOPCNTDQ, AVX5124FMAPS, AVX512VNNI, AVX5124VNNIW, SERIALIZE, UINTR, HRESET, AMXTILE, AMXINT8, AMXBF16, KL, WIDEKL, AVXVNNI, AVX512FP16 or CLDE- MOTE extended instruction sets. Each has a corresponding --mmnnoo-- op- tion to disable use of these instructions. These extensions are also available as built-in functions: see xx8866 BBuuiilltt--iinn FFuunnccttiioonnss, for details of the functions enabled and dis- abled by these switches. To generate SSE/SSE2 instructions automatically from floating-point code (as opposed to 387 instructions), see --mmffppmmaatthh==ssssee. GCC depresses SSEx instructions when --mmaavvxx is used. Instead, it generates new AVX instructions or AVX equivalence for all SSEx in- structions when needed. These options enable GCC to use these extended instructions in gen- erated code, even without --mmffppmmaatthh==ssssee. Applications that perform run-time CPU detection must compile separate files for each sup- ported architecture, using the appropriate flags. In particular, the file containing the CPU detection code should be compiled with- out these options. --mmdduummpp--ttuunnee--ffeeaattuurreess This option instructs GCC to dump the names of the x86 performance tuning features and default settings. The names can be used in --mmttuunnee--ccttrrll==_f_e_a_t_u_r_e_-_l_i_s_t. --mmttuunnee--ccttrrll==_f_e_a_t_u_r_e_-_l_i_s_t This option is used to do fine grain control of x86 code generation features. _f_e_a_t_u_r_e_-_l_i_s_t is a comma separated list of _f_e_a_t_u_r_e names. See also --mmdduummpp--ttuunnee--ffeeaattuurreess. When specified, the _f_e_a_t_u_r_e is turned on if it is not preceded with ^^, otherwise, it is turned off. --mmttuunnee--ccttrrll==_f_e_a_t_u_r_e_-_l_i_s_t is intended to be used by GCC devel- opers. Using it may lead to code paths not covered by testing and can potentially result in compiler ICEs or runtime errors. --mmnnoo--ddeeffaauulltt This option instructs GCC to turn off all tunable features. See also --mmttuunnee--ccttrrll==_f_e_a_t_u_r_e_-_l_i_s_t and --mmdduummpp--ttuunnee--ffeeaattuurreess. --mmcclldd This option instructs GCC to emit a "cld" instruction in the pro- logue of functions that use string instructions. String instruc- tions depend on the DF flag to select between autoincrement or au- todecrement mode. While the ABI specifies the DF flag to be cleared on function entry, some operating systems violate this specification by not clearing the DF flag in their exception dis- patchers. The exception handler can be invoked with the DF flag set, which leads to wrong direction mode when string instructions are used. This option can be enabled by default on 32-bit x86 tar- gets by configuring GCC with the ----eennaabbllee--cclldd configure option. Generation of "cld" instructions can be suppressed with the --mmnnoo--cclldd compiler option in this case. --mmvvzzeerroouuppppeerr This option instructs GCC to emit a "vzeroupper" instruction before a transfer of control flow out of the function to minimize the AVX to SSE transition penalty as well as remove unnecessary "zeroupper" intrinsics. --mmpprreeffeerr--aavvxx112288 This option instructs GCC to use 128-bit AVX instructions instead of 256-bit AVX instructions in the auto-vectorizer. --mmpprreeffeerr--vveeccttoorr--wwiiddtthh==_o_p_t This option instructs GCC to use _o_p_t-bit vector width in instruc- tions instead of default on the selected platform. --mmmmoovvee--mmaaxx==_b_i_t_s This option instructs GCC to set the maximum number of bits can be moved from memory to memory efficiently to _b_i_t_s. The valid _b_i_t_s are 128, 256 and 512. --mmssttoorree--mmaaxx==_b_i_t_s This option instructs GCC to set the maximum number of bits can be stored to memory efficiently to _b_i_t_s. The valid _b_i_t_s are 128, 256 and 512. nnoonnee No extra limitations applied to GCC other than defined by the selected platform. 112288 Prefer 128-bit vector width for instructions. 225566 Prefer 256-bit vector width for instructions. 551122 Prefer 512-bit vector width for instructions. --mmccxx1166 This option enables GCC to generate "CMPXCHG16B" instructions in 64-bit code to implement compare-and-exchange operations on 16-byte aligned 128-bit objects. This is useful for atomic updates of data structures exceeding one machine word in size. The compiler uses this instruction to implement ____ssyynncc BBuuiillttiinnss. However, for ____aattoommiicc BBuuiillttiinnss operating on 128-bit integers, a library call is always used. --mmssaahhff This option enables generation of "SAHF" instructions in 64-bit code. Early Intel Pentium 4 CPUs with Intel 64 support, prior to the introduction of Pentium 4 G1 step in December 2005, lacked the "LAHF" and "SAHF" instructions which are supported by AMD64. These are load and store instructions, respectively, for certain status flags. In 64-bit mode, the "SAHF" instruction is used to optimize "fmod", "drem", and "remainder" built-in functions; see OOtthheerr BBuuiillttiinnss for details. --mmmmoovvbbee This option enables use of the "movbe" instruction to implement "__builtin_bswap32" and "__builtin_bswap64". --mmsshhssttkk The --mmsshhssttkk option enables shadow stack built-in functions from x86 Control-flow Enforcement Technology (CET). --mmccrrcc3322 This option enables built-in functions "__builtin_ia32_crc32qi", "__builtin_ia32_crc32hi", "__builtin_ia32_crc32si" and "__builtin_ia32_crc32di" to generate the "crc32" machine instruc- tion. --mmmmwwaaiitt This option enables built-in functions "__builtin_ia32_monitor", and "__builtin_ia32_mwait" to generate the "monitor" and "mwait" machine instructions. --mmrreecciipp This option enables use of "RCPSS" and "RSQRTSS" instructions (and their vectorized variants "RCPPS" and "RSQRTPS") with an additional Newton-Raphson step to increase precision instead of "DIVSS" and "SQRTSS" (and their vectorized variants) for single-precision floating-point arguments. These instructions are generated only when --ffuunnssaaffee--mmaatthh--ooppttiimmiizzaattiioonnss is enabled together with --ffffii-- nniittee--mmaatthh--oonnllyy and --ffnnoo--ttrraappppiinngg--mmaatthh. Note that while the throughput of the sequence is higher than the throughput of the non-reciprocal instruction, the precision of the sequence can be decreased by up to 2 ulp (i.e. the inverse of 1.0 equals 0.99999994). Note that GCC implements "1.0f/sqrtf(_x_)_" in terms of "RSQRTSS" (or "RSQRTPS") already with --ffffaasstt--mmaatthh (or the above option combina- tion), and doesn't need --mmrreecciipp. Also note that GCC emits the above sequence with additional Newton- Raphson step for vectorized single-float division and vectorized "sqrtf(_x_)_" already with --ffffaasstt--mmaatthh (or the above option combina- tion), and doesn't need --mmrreecciipp. --mmrreecciipp==_o_p_t This option controls which reciprocal estimate instructions may be used. _o_p_t is a comma-separated list of options, which may be pre- ceded by a !! to invert the option: aallll Enable all estimate instructions. ddeeffaauulltt Enable the default instructions, equivalent to --mmrreecciipp. nnoonnee Disable all estimate instructions, equivalent to --mmnnoo--rreecciipp. ddiivv Enable the approximation for scalar division. vveecc--ddiivv Enable the approximation for vectorized division. ssqqrrtt Enable the approximation for scalar square root. vveecc--ssqqrrtt Enable the approximation for vectorized square root. So, for example, --mmrreecciipp==aallll,,!!ssqqrrtt enables all of the reciprocal approximations, except for square root. --mmvveecclliibbaabbii==_t_y_p_e Specifies the ABI type to use for vectorizing intrinsics using an external library. Supported values for _t_y_p_e are ssvvmmll for the Intel short vector math library and aaccmmll for the AMD math core library. To use this option, both --ffttrreeee--vveeccttoorriizzee and --ffuunnssaaffee--mmaatthh--ooppttii-- mmiizzaattiioonnss have to be enabled, and an SVML or ACML ABI-compatible library must be specified at link time. GCC currently emits calls to "vmldExp2", "vmldLn2", "vmldLog102", "vmldPow2", "vmldTanh2", "vmldTan2", "vmldAtan2", "vmldAtanh2", "vmldCbrt2", "vmldSinh2", "vmldSin2", "vmldAsinh2", "vmldAsin2", "vmldCosh2", "vmldCos2", "vmldAcosh2", "vmldAcos2", "vmlsExp4", "vmlsLn4", "vmlsLog104", "vmlsPow4", "vmlsTanh4", "vmlsTan4", "vml- sAtan4", "vmlsAtanh4", "vmlsCbrt4", "vmlsSinh4", "vmlsSin4", "vml- sAsinh4", "vmlsAsin4", "vmlsCosh4", "vmlsCos4", "vmlsAcosh4" and "vmlsAcos4" for corresponding function type when --mmvveecclliibbaabbii==ssvvmmll is used, and "__vrd2_sin", "__vrd2_cos", "__vrd2_exp", "__vrd2_log", "__vrd2_log2", "__vrd2_log10", "__vrs4_sinf", "__vrs4_cosf", "__vrs4_expf", "__vrs4_logf", "__vrs4_log2f", "__vrs4_log10f" and "__vrs4_powf" for the corresponding function type when --mmvveecclliibbaabbii==aaccmmll is used. --mmaabbii==_n_a_m_e Generate code for the specified calling convention. Permissible values are ssyyssvv for the ABI used on GNU/Linux and other systems, and mmss for the Microsoft ABI. The default is to use the Microsoft ABI when targeting Microsoft Windows and the SysV ABI on all other systems. You can control this behavior for specific functions by using the function attributes "ms_abi" and "sysv_abi". --mmffoorrccee--iinnddiirreecctt--ccaallll Force all calls to functions to be indirect. This is useful when using Intel Processor Trace where it generates more precise timing information for function calls. --mmmmaannuuaall--eennddbbrr Insert ENDBR instruction at function entry only via the "cf_check" function attribute. This is useful when used with the option --ffccff--pprrootteeccttiioonn==bbrraanncchh to control ENDBR insertion at the function entry. --mmccaallll--mmss22ssyyssvv--xxlloogguueess Due to differences in 64-bit ABIs, any Microsoft ABI function that calls a System V ABI function must consider RSI, RDI and XMM6-15 as clobbered. By default, the code for saving and restoring these registers is emitted inline, resulting in fairly lengthy prologues and epilogues. Using --mmccaallll--mmss22ssyyssvv--xxlloogguueess emits prologues and epilogues that use stubs in the static portion of libgcc to perform these saves and restores, thus reducing function size at the cost of a few extra instructions. --mmttllss--ddiiaalleecctt==_t_y_p_e Generate code to access thread-local storage using the ggnnuu or ggnnuu22 conventions. ggnnuu is the conservative default; ggnnuu22 is more effi- cient, but it may add compile- and run-time requirements that can- not be satisfied on all systems. --mmppuusshh--aarrggss --mmnnoo--ppuusshh--aarrggss Use PUSH operations to store outgoing parameters. This method is shorter and usually equally fast as method using SUB/MOV operations and is enabled by default. In some cases disabling it may improve performance because of improved scheduling and reduced dependen- cies. --mmaaccccuummuullaattee--oouuttggooiinngg--aarrggss If enabled, the maximum amount of space required for outgoing argu- ments is computed in the function prologue. This is faster on most modern CPUs because of reduced dependencies, improved scheduling and reduced stack usage when the preferred stack boundary is not equal to 2. The drawback is a notable increase in code size. This switch implies --mmnnoo--ppuusshh--aarrggss. --mmtthhrreeaaddss Support thread-safe exception handling on MinGW. Programs that rely on thread-safe exception handling must compile and link all code with the --mmtthhrreeaaddss option. When compiling, --mmtthhrreeaaddss defines --DD__MMTT; when linking, it links in a special thread helper library --llmmiinnggwwtthhrrdd which cleans up per-thread exception-handling data. --mmmmss--bbiittffiieellddss --mmnnoo--mmss--bbiittffiieellddss Enable/disable bit-field layout compatible with the native Micro- soft Windows compiler. If "packed" is used on a structure, or if bit-fields are used, it may be that the Microsoft ABI lays out the structure differently than the way GCC normally does. Particularly when moving packed data between functions compiled with GCC and the native Microsoft compiler (either via function call or as data in a file), it may be necessary to access either format. This option is enabled by default for Microsoft Windows targets. This behavior can also be controlled locally by use of variable or type attributes. For more information, see xx8866 VVaarriiaabbllee AAttttrriibbuutteess and xx8866 TTyyppee AAttttrriibbuutteess. The Microsoft structure layout algorithm is fairly simple with the exception of the bit-field packing. The padding and alignment of members of structures and whether a bit-field can straddle a stor- age-unit boundary are determine by these rules: 1. Structure members are stored sequentially in the order in which they are declared: the first member has the lowest memory address and the last member the highest. 2. Every data object has an alignment requirement. The alignment requirement for all data except structures, unions, and arrays is either the size of the object or the current packing size (specified with either the "aligned" attribute or the "pack" pragma), whichever is less. For structures, unions, and arrays, the alignment requirement is the largest alignment requirement of its members. Every object is allocated an offset so that: offset % alignment_requirement == 0 3. Adjacent bit-fields are packed into the same 1-, 2-, or 4-byte allocation unit if the integral types are the same size and if the next bit-field fits into the current allocation unit without cross- ing the boundary imposed by the common alignment requirements of the bit-fields. MSVC interprets zero-length bit-fields in the following ways: 1. If a zero-length bit-field is inserted between two bit-fields that are normally coalesced, the bit-fields are not coalesced. For example: struct { unsigned long bf_1 : 12; unsigned long : 0; unsigned long bf_2 : 12; } t1; The size of "t1" is 8 bytes with the zero-length bit-field. If the zero-length bit-field were removed, "t1"'s size would be 4 bytes. 2. If a zero-length bit-field is inserted after a bit-field, "foo", and the alignment of the zero-length bit-field is greater than the mem- ber that follows it, "bar", "bar" is aligned as the type of the zero-length bit-field. For example: struct { char foo : 4; short : 0; char bar; } t2; struct { char foo : 4; short : 0; double bar; } t3; For "t2", "bar" is placed at offset 2, rather than offset 1. Accordingly, the size of "t2" is 4. For "t3", the zero-length bit-field does not affect the alignment of "bar" or, as a re- sult, the size of the structure. Taking this into account, it is important to note the follow- ing: 1. If a zero-length bit-field follows a normal bit-field, the type of the zero-length bit-field may affect the alignment of the structure as whole. For example, "t2" has a size of 4 bytes, since the zero-length bit-field follows a normal bit-field, and is of type short. 2. Even if a zero-length bit-field is not followed by a normal bit-field, it may still affect the alignment of the structure: struct { char foo : 6; long : 0; } t4; Here, "t4" takes up 4 bytes. 3. Zero-length bit-fields following non-bit-field members are ig- nored: struct { char foo; long : 0; char bar; } t5; Here, "t5" takes up 2 bytes. --mmnnoo--aalliiggnn--ssttrriinnggooppss Do not align the destination of inlined string operations. This switch reduces code size and improves performance in case the des- tination is already aligned, but GCC doesn't know about it. --mmiinnlliinnee--aallll--ssttrriinnggooppss By default GCC inlines string operations only when the destination is known to be aligned to least a 4-byte boundary. This enables more inlining and increases code size, but may improve performance of code that depends on fast "memcpy" and "memset" for short lengths. The option enables inline expansion of "strlen" for all pointer alignments. --mmiinnlliinnee--ssttrriinnggooppss--ddyynnaammiiccaallllyy For string operations of unknown size, use run-time checks with in- line code for small blocks and a library call for large blocks. --mmssttrriinnggoopp--ssttrraatteeggyy==_a_l_g Override the internal decision heuristic for the particular algo- rithm to use for inlining string operations. The allowed values for _a_l_g are: rreepp__bbyyttee rreepp__44bbyyttee rreepp__88bbyyttee Expand using i386 "rep" prefix of the specified size. bbyyttee__lloooopp lloooopp uunnrroolllleedd__lloooopp Expand into an inline loop. lliibbccaallll Always use a library call. --mmmmeemmccppyy--ssttrraatteeggyy==_s_t_r_a_t_e_g_y Override the internal decision heuristic to decide if "__builtin_memcpy" should be inlined and what inline algorithm to use when the expected size of the copy operation is known. _s_t_r_a_t_e_g_y is a comma-separated list of _a_l_g:_m_a_x___s_i_z_e:_d_e_s_t___a_l_i_g_n triplets. _a_l_g is specified in --mmssttrriinnggoopp--ssttrraatteeggyy, _m_a_x___s_i_z_e specifies the max byte size with which inline algorithm _a_l_g is allowed. For the last triplet, the _m_a_x___s_i_z_e must be "-1". The _m_a_x___s_i_z_e of the triplets in the list must be specified in increasing order. The minimal byte size for _a_l_g is 0 for the first triplet and "_m_a_x___s_i_z_e _+ _1_" of the preceding range. --mmmmeemmsseett--ssttrraatteeggyy==_s_t_r_a_t_e_g_y The option is similar to --mmmmeemmccppyy--ssttrraatteeggyy== except that it is to control "__builtin_memset" expansion. --mmoommiitt--lleeaaff--ffrraammee--ppooiinntteerr Don't keep the frame pointer in a register for leaf functions. This avoids the instructions to save, set up, and restore frame pointers and makes an extra register available in leaf functions. The option --ffoommiitt--lleeaaff--ffrraammee--ppooiinntteerr removes the frame pointer for leaf functions, which might make debugging harder. --mmttllss--ddiirreecctt--sseegg--rreeffss --mmnnoo--ttllss--ddiirreecctt--sseegg--rreeffss Controls whether TLS variables may be accessed with offsets from the TLS segment register (%gs for 32-bit, %fs for 64-bit), or whether the thread base pointer must be added. Whether or not this is valid depends on the operating system, and whether it maps the segment to cover the entire TLS area. For systems that use the GNU C Library, the default is on. --mmssssee22aavvxx --mmnnoo--ssssee22aavvxx Specify that the assembler should encode SSE instructions with VEX prefix. The option --mmaavvxx turns this on by default. --mmffeennttrryy --mmnnoo--ffeennttrryy If profiling is active (--ppgg), put the profiling counter call before the prologue. Note: On x86 architectures the attribute "ms_hook_prologue" isn't possible at the moment for --mmffeennttrryy and --ppgg. --mmrreeccoorrdd--mmccoouunntt --mmnnoo--rreeccoorrdd--mmccoouunntt If profiling is active (--ppgg), generate a __mcount_loc section that contains pointers to each profiling call. This is useful for auto- matically patching and out calls. --mmnnoopp--mmccoouunntt --mmnnoo--nnoopp--mmccoouunntt If profiling is active (--ppgg), generate the calls to the profiling functions as NOPs. This is useful when they should be patched in later dynamically. This is likely only useful together with --mmrreeccoorrdd--mmccoouunntt. --mmiinnssttrruummeenntt--rreettuurrnn==_t_y_p_e Instrument function exit in -pg -mfentry instrumented functions with call to specified function. This only instruments true returns ending with ret, but not sibling calls ending with jump. Valid types are _n_o_n_e to not instrument, _c_a_l_l to generate a call to __re- turn__, or _n_o_p_5 to generate a 5 byte nop. --mmrreeccoorrdd--rreettuurrnn --mmnnoo--rreeccoorrdd--rreettuurrnn Generate a __return_loc section pointing to all return instrumenta- tion code. --mmffeennttrryy--nnaammee==_n_a_m_e Set name of __fentry__ symbol called at function entry for -pg -mfentry functions. --mmffeennttrryy--sseeccttiioonn==_n_a_m_e Set name of section to record -mrecord-mcount calls (default __mcount_loc). --mmsskkiipp--rraaxx--sseettuupp --mmnnoo--sskkiipp--rraaxx--sseettuupp When generating code for the x86-64 architecture with SSE exten- sions disabled, --mmsskkiipp--rraaxx--sseettuupp can be used to skip setting up RAX register when there are no variable arguments passed in vector reg- isters. WWaarrnniinngg:: Since RAX register is used to avoid unnecessarily saving vector registers on stack when passing variable arguments, the im- pacts of this option are callees may waste some stack space, misbe- have or jump to a random location. GCC 4.4 or newer don't have those issues, regardless the RAX register value. --mm88bbiitt--iiddiivv --mmnnoo--88bbiitt--iiddiivv On some processors, like Intel Atom, 8-bit unsigned integer divide is much faster than 32-bit/64-bit integer divide. This option gen- erates a run-time check. If both dividend and divisor are within range of 0 to 255, 8-bit unsigned integer divide is used instead of 32-bit/64-bit integer divide. --mmaavvxx225566--sspplliitt--uunnaalliiggnneedd--llooaadd --mmaavvxx225566--sspplliitt--uunnaalliiggnneedd--ssttoorree Split 32-byte AVX unaligned load and store. --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd==_g_u_a_r_d --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--rreegg==_r_e_g --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ooffffsseett==_o_f_f_s_e_t Generate stack protection code using canary at _g_u_a_r_d. Supported locations are gglloobbaall for global canary or ttllss for per-thread canary in the TLS block (the default). This option has effect only when --ffssttaacckk--pprrootteeccttoorr or --ffssttaacckk--pprrootteeccttoorr--aallll is specified. With the latter choice the options --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--rreegg==_r_e_g and --mmssttaacckk--pprrootteeccttoorr--gguuaarrdd--ooffffsseett==_o_f_f_s_e_t furthermore specify which segment register (%fs or %gs) to use as base register for reading the canary, and from what offset from that base register. The de- fault for those is as specified in the relevant ABI. --mmggeenneerraall--rreeggss--oonnllyy Generate code that uses only the general-purpose registers. This prevents the compiler from using floating-point, vector, mask and bound registers. --mmrreellaaxx--ccmmppxxcchhgg--lloooopp Relax cmpxchg loop by emitting an early load and compare before cm- pxchg, execute pause if load value is not expected. This reduces excessive cachline bouncing when and works for all atomic logic fetch builtins that generates compare and swap loop. --mmiinnddiirreecctt--bbrraanncchh==_c_h_o_i_c_e Convert indirect call and jump with _c_h_o_i_c_e. The default is kkeeeepp, which keeps indirect call and jump unmodified. tthhuunnkk converts in- direct call and jump to call and return thunk. tthhuunnkk--iinnlliinnee con- verts indirect call and jump to inlined call and return thunk. tthhuunnkk--eexxtteerrnn converts indirect call and jump to external call and return thunk provided in a separate object file. You can control this behavior for a specific function by using the function attri- bute "indirect_branch". Note that --mmccmmooddeell==llaarrggee is incompatible with --mmiinnddii-- rreecctt--bbrraanncchh==tthhuunnkk and --mmiinnddiirreecctt--bbrraanncchh==tthhuunnkk--eexxtteerrnn since the thunk function may not be reachable in the large code model. Note that --mmiinnddiirreecctt--bbrraanncchh==tthhuunnkk--eexxtteerrnn is compatible with --ffccff--pprrootteeccttiioonn==bbrraanncchh since the external thunk can be made to en- able control-flow check. --mmffuunnccttiioonn--rreettuurrnn==_c_h_o_i_c_e Convert function return with _c_h_o_i_c_e. The default is kkeeeepp, which keeps function return unmodified. tthhuunnkk converts function return to call and return thunk. tthhuunnkk--iinnlliinnee converts function return to inlined call and return thunk. tthhuunnkk--eexxtteerrnn converts function re- turn to external call and return thunk provided in a separate ob- ject file. You can control this behavior for a specific function by using the function attribute "function_return". Note that --mmiinnddiirreecctt--rreettuurrnn==tthhuunnkk--eexxtteerrnn is compatible with --ffccff--pprrootteeccttiioonn==bbrraanncchh since the external thunk can be made to en- able control-flow check. Note that --mmccmmooddeell==llaarrggee is incompatible with --mmffuunnccttiioonn--rree-- ttuurrnn==tthhuunnkk and --mmffuunnccttiioonn--rreettuurrnn==tthhuunnkk--eexxtteerrnn since the thunk func- tion may not be reachable in the large code model. --mmiinnddiirreecctt--bbrraanncchh--rreeggiisstteerr Force indirect call and jump via register. --mmhhaarrddeenn--ssllss==_c_h_o_i_c_e Generate code to mitigate against straight line speculation (SLS) with _c_h_o_i_c_e. The default is nnoonnee which disables all SLS hardening. rreettuurrnn enables SLS hardening for function returns. iinnddiirreecctt--jjmmpp enables SLS hardening for indirect jumps. aallll enables all SLS hardening. --mmiinnddiirreecctt--bbrraanncchh--ccss--pprreeffiixx Add CS prefix to call and jmp to indirect thunk with branch target in r8-r15 registers so that the call and jmp instruction length is 6 bytes to allow them to be replaced with llffeennccee;; ccaallll **%%rr88--rr1155 or llffeennccee;; jjmmpp **%%rr88--rr1155 at run-time. These --mm switches are supported in addition to the above on x86-64 pro- cessors in 64-bit environments. --mm3322 --mm6644 --mmxx3322 --mm1166 --mmiiaammccuu Generate code for a 16-bit, 32-bit or 64-bit environment. The --mm3322 option sets "int", "long", and pointer types to 32 bits, and gener- ates code that runs on any i386 system. The --mm6644 option sets "int" to 32 bits and "long" and pointer types to 64 bits, and generates code for the x86-64 architecture. For Darwin only the --mm6644 option also turns off the --ffnnoo--ppiicc and --mmddyy-- nnaammiicc--nnoo--ppiicc options. The --mmxx3322 option sets "int", "long", and pointer types to 32 bits, and generates code for the x86-64 architecture. The --mm1166 option is the same as --mm3322, except for that it outputs the ".code16gcc" assembly directive at the beginning of the assembly output so that the binary can run in 16-bit mode. The --mmiiaammccuu option generates code which conforms to Intel MCU psABI. It requires the --mm3322 option to be turned on. --mmnnoo--rreedd--zzoonnee Do not use a so-called "red zone" for x86-64 code. The red zone is mandated by the x86-64 ABI; it is a 128-byte area beyond the loca- tion of the stack pointer that is not modified by signal or inter- rupt handlers and therefore can be used for temporary data without adjusting the stack pointer. The flag --mmnnoo--rreedd--zzoonnee disables this red zone. --mmccmmooddeell==ssmmaallll Generate code for the small code model: the program and its symbols must be linked in the lower 2 GB of the address space. Pointers are 64 bits. Programs can be statically or dynamically linked. This is the default code model. --mmccmmooddeell==kkeerrnneell Generate code for the kernel code model. The kernel runs in the negative 2 GB of the address space. This model has to be used for Linux kernel code. --mmccmmooddeell==mmeeddiiuumm Generate code for the medium model: the program is linked in the lower 2 GB of the address space. Small symbols are also placed there. Symbols with sizes larger than --mmllaarrggee--ddaattaa--tthhrreesshhoolldd are put into large data or BSS sections and can be located above 2GB. Programs can be statically or dynamically linked. --mmccmmooddeell==llaarrggee Generate code for the large model. This model makes no assumptions about addresses and sizes of sections. --mmaaddddrreessss--mmooddee==lloonngg Generate code for long address mode. This is only supported for 64-bit and x32 environments. It is the default address mode for 64-bit environments. --mmaaddddrreessss--mmooddee==sshhoorrtt Generate code for short address mode. This is only supported for 32-bit and x32 environments. It is the default address mode for 32-bit and x32 environments. --mmnneeeeddeedd --mmnnoo--nneeeeddeedd Emit GNU_PROPERTY_X86_ISA_1_NEEDED GNU property for Linux target to indicate the micro-architecture ISA level required to execute the binary. --mmnnoo--ddiirreecctt--eexxtteerrnn--aacccceessss Without --ffppiicc nor --ffPPIICC, always use the GOT pointer to access ex- ternal symbols. With --ffppiicc or --ffPPIICC, treat access to protected symbols as local symbols. The default is --mmddiirreecctt--eexxtteerrnn--aacccceessss. WWaarrnniinngg:: shared libraries compiled with --mmnnoo--ddiirreecctt--eexxtteerrnn--aacccceessss and executable compiled with --mmddiirreecctt--eexxtteerrnn--aacccceessss may not be bi- nary compatible if protected symbols are used in shared libraries and executable. _x_8_6 _W_i_n_d_o_w_s _O_p_t_i_o_n_s These additional options are available for Microsoft Windows targets: --mmccoonnssoollee This option specifies that a console application is to be gener- ated, by instructing the linker to set the PE header subsystem type required for console applications. This option is available for Cygwin and MinGW targets and is enabled by default on those tar- gets. --mmddllll This option is available for Cygwin and MinGW targets. It speci- fies that a DLL---a dynamic link library---is to be generated, en- abling the selection of the required runtime startup object and en- try point. --mmnnoopp--ffuunn--ddlllliimmppoorrtt This option is available for Cygwin and MinGW targets. It speci- fies that the "dllimport" attribute should be ignored. --mmtthhrreeaaddss This option is available for MinGW targets. It specifies that MinGW-specific thread support is to be used. --mmuunniiccooddee This option is available for MinGW-w64 targets. It causes the "UNICODE" preprocessor macro to be predefined, and chooses Unicode- capable runtime startup code. --mmwwiinn3322 This option is available for Cygwin and MinGW targets. It speci- fies that the typical Microsoft Windows predefined macros are to be set in the pre-processor, but does not influence the choice of run- time library/startup code. --mmwwiinnddoowwss This option is available for Cygwin and MinGW targets. It speci- fies that a GUI application is to be generated by instructing the linker to set the PE header subsystem type appropriately. --ffnnoo--sseett--ssttaacckk--eexxeeccuuttaabbllee This option is available for MinGW targets. It specifies that the executable flag for the stack used by nested functions isn't set. This is necessary for binaries running in kernel mode of Microsoft Windows, as there the User32 API, which is used to set executable privileges, isn't available. --ffwwrriittaabbllee--rreellooccaatteedd--rrddaattaa This option is available for MinGW and Cygwin targets. It speci- fies that relocated-data in read-only section is put into the ".data" section. This is a necessary for older runtimes not sup- porting modification of ".rdata" sections for pseudo-relocation. --mmppee--aalliiggnneedd--ccoommmmoonnss This option is available for Cygwin and MinGW targets. It speci- fies that the GNU extension to the PE file format that permits the correct alignment of COMMON variables should be used when generat- ing code. It is enabled by default if GCC detects that the target assembler found during configuration supports the feature. See also under xx8866 OOppttiioonnss for standard options. _X_s_t_o_r_m_y_1_6 _O_p_t_i_o_n_s These options are defined for Xstormy16: --mmssiimm Choose startup files and linker script suitable for the simulator. _X_t_e_n_s_a _O_p_t_i_o_n_s These options are supported for Xtensa targets: --mmccoonnsstt1166 --mmnnoo--ccoonnsstt1166 Enable or disable use of "CONST16" instructions for loading con- stant values. The "CONST16" instruction is currently not a stan- dard option from Tensilica. When enabled, "CONST16" instructions are always used in place of the standard "L32R" instructions. The use of "CONST16" is enabled by default only if the "L32R" instruc- tion is not available. --mmffuusseedd--mmaadddd --mmnnoo--ffuusseedd--mmaadddd Enable or disable use of fused multiply/add and multiply/subtract instructions in the floating-point option. This has no effect if the floating-point option is not also enabled. Disabling fused multiply/add and multiply/subtract instructions forces the compiler to use separate instructions for the multiply and add/subtract op- erations. This may be desirable in some cases where strict IEEE 754-compliant results are required: the fused multiply add/subtract instructions do not round the intermediate result, thereby produc- ing results with _m_o_r_e bits of precision than specified by the IEEE standard. Disabling fused multiply add/subtract instructions also ensures that the program output is not sensitive to the compiler's ability to combine multiply and add/subtract operations. --mmsseerriiaalliizzee--vvoollaattiillee --mmnnoo--sseerriiaalliizzee--vvoollaattiillee When this option is enabled, GCC inserts "MEMW" instructions before "volatile" memory references to guarantee sequential consistency. The default is --mmsseerriiaalliizzee--vvoollaattiillee. Use --mmnnoo--sseerriiaalliizzee--vvoollaattiillee to omit the "MEMW" instructions. --mmffoorrccee--nnoo--ppiicc For targets, like GNU/Linux, where all user-mode Xtensa code must be position-independent code (PIC), this option disables PIC for compiling kernel code. --mmtteexxtt--sseeccttiioonn--lliitteerraallss --mmnnoo--tteexxtt--sseeccttiioonn--lliitteerraallss These options control the treatment of literal pools. The default is --mmnnoo--tteexxtt--sseeccttiioonn--lliitteerraallss, which places literals in a separate section in the output file. This allows the literal pool to be placed in a data RAM/ROM, and it also allows the linker to combine literal pools from separate object files to remove redundant liter- als and improve code size. With --mmtteexxtt--sseeccttiioonn--lliitteerraallss, the lit- erals are interspersed in the text section in order to keep them as close as possible to their references. This may be necessary for large assembly files. Literals for each function are placed right before that function. --mmaauuttoo--lliittppoooollss --mmnnoo--aauuttoo--lliittppoooollss These options control the treatment of literal pools. The default is --mmnnoo--aauuttoo--lliittppoooollss, which places literals in a separate section in the output file unless --mmtteexxtt--sseeccttiioonn--lliitteerraallss is used. With --mmaauuttoo--lliittppoooollss the literals are interspersed in the text section by the assembler. Compiler does not produce explicit ".literal" directives and loads literals into registers with "MOVI" instruc- tions instead of "L32R" to let the assembler do relaxation and place literals as necessary. This option allows assembler to cre- ate several literal pools per function and assemble very big func- tions, which may not be possible with --mmtteexxtt--sseeccttiioonn--lliitteerraallss. --mmttaarrggeett--aalliiggnn --mmnnoo--ttaarrggeett--aalliiggnn When this option is enabled, GCC instructs the assembler to auto- matically align instructions to reduce branch penalties at the ex- pense of some code density. The assembler attempts to widen den- sity instructions to align branch targets and the instructions fol- lowing call instructions. If there are not enough preceding safe density instructions to align a target, no widening is performed. The default is --mmttaarrggeett--aalliiggnn. These options do not affect the treatment of auto-aligned instructions like "LOOP", which the as- sembler always aligns, either by widening density instructions or by inserting NOP instructions. --mmlloonnggccaallllss --mmnnoo--lloonnggccaallllss When this option is enabled, GCC instructs the assembler to trans- late direct calls to indirect calls unless it can determine that the target of a direct call is in the range allowed by the call in- struction. This translation typically occurs for calls to func- tions in other source files. Specifically, the assembler trans- lates a direct "CALL" instruction into an "L32R" followed by a "CALLX" instruction. The default is --mmnnoo--lloonnggccaallllss. This option should be used in programs where the call target can potentially be out of range. This option is implemented in the assembler, not the compiler, so the assembly code generated by GCC still shows direct call instructions---look at the disassembled object code to see the actual instructions. Note that the assembler uses an indirect call for every cross-file call, not just those that really are out of range. --mmaabbii==_n_a_m_e Generate code for the specified ABI. Permissible values are: ccaallll00, wwiinnddoowweedd. Default ABI is chosen by the Xtensa core configu- ration. --mmaabbii==ccaallll00 When this option is enabled function parameters are passed in reg- isters "a2" through "a7", registers "a12" through "a15" are caller-saved, and register "a15" may be used as a frame pointer. When this version of the ABI is enabled the C preprocessor symbol "__XTENSA_CALL0_ABI__" is defined. --mmaabbii==wwiinnddoowweedd When this option is enabled function parameters are passed in reg- isters "a10" through "a15", and called function rotates register window by 8 registers on entry so that its arguments are found in registers "a2" through "a7". Register "a7" may be used as a frame pointer. Register window is rotated 8 registers back upon return. When this version of the ABI is enabled the C preprocessor symbol "__XTENSA_WINDOWED_ABI__" is defined. _z_S_e_r_i_e_s _O_p_t_i_o_n_s These are listed under EENNVVIIRROONNMMEENNTT This section describes several environment variables that affect how GCC operates. Some of them work by specifying directories or prefixes to use when searching for various kinds of files. Some are used to specify other aspects of the compilation environment. Note that you can also specify places to search using options such as --BB, --II and --LL. These take precedence over places specified using envi- ronment variables, which in turn take precedence over those specified by the configuration of GCC. LLAANNGG LLCC__CCTTYYPPEE LLCC__MMEESSSSAAGGEESS LLCC__AALLLL These environment variables control the way that GCC uses localiza- tion information which allows GCC to work with different national conventions. GCC inspects the locale categories LLCC__CCTTYYPPEE and LLCC__MMEESSSSAAGGEESS if it has been configured to do so. These locale cate- gories can be set to any value supported by your installation. A typical value is eenn__GGBB..UUTTFF--88 for English in the United Kingdom en- coded in UTF-8. The LLCC__CCTTYYPPEE environment variable specifies character classifica- tion. GCC uses it to determine the character boundaries in a string; this is needed for some multibyte encodings that contain quote and escape characters that are otherwise interpreted as a string end or escape. The LLCC__MMEESSSSAAGGEESS environment variable specifies the language to use in diagnostic messages. If the LLCC__AALLLL environment variable is set, it overrides the value of LLCC__CCTTYYPPEE and LLCC__MMEESSSSAAGGEESS; otherwise, LLCC__CCTTYYPPEE and LLCC__MMEESSSSAAGGEESS default to the value of the LLAANNGG environment variable. If none of these variables are set, GCC defaults to traditional C English be- havior. TTMMPPDDIIRR If TTMMPPDDIIRR is set, it specifies the directory to use for temporary files. GCC uses temporary files to hold the output of one stage of compilation which is to be used as input to the next stage: for ex- ample, the output of the preprocessor, which is the input to the compiler proper. GGCCCC__CCOOMMPPAARREE__DDEEBBUUGG Setting GGCCCC__CCOOMMPPAARREE__DDEEBBUUGG is nearly equivalent to passing --ffccoomm-- ppaarree--ddeebbuugg to the compiler driver. See the documentation of this option for more details. GGCCCC__EEXXEECC__PPRREEFFIIXX If GGCCCC__EEXXEECC__PPRREEFFIIXX is set, it specifies a prefix to use in the names of the subprograms executed by the compiler. No slash is added when this prefix is combined with the name of a subprogram, but you can specify a prefix that ends with a slash if you wish. If GGCCCC__EEXXEECC__PPRREEFFIIXX is not set, GCC attempts to figure out an appro- priate prefix to use based on the pathname it is invoked with. If GCC cannot find the subprogram using the specified prefix, it tries looking in the usual places for the subprogram. The default value of GGCCCC__EEXXEECC__PPRREEFFIIXX is _p_r_e_f_i_x_/_l_i_b_/_g_c_c_/ where _p_r_e_- _f_i_x is the prefix to the installed compiler. In many cases _p_r_e_f_i_x is the value of "prefix" when you ran the _c_o_n_f_i_g_u_r_e script. Other prefixes specified with --BB take precedence over this prefix. This prefix is also used for finding files such as _c_r_t_0_._o that are used for linking. In addition, the prefix is used in an unusual way in finding the directories to search for header files. For each of the standard directories whose name normally begins with //uussrr//llooccaall//lliibb//ggcccc (more precisely, with the value of GGCCCC__IINNCCLLUUDDEE__DDIIRR), GCC tries re- placing that beginning with the specified prefix to produce an al- ternate directory name. Thus, with --BBffoooo//, GCC searches _f_o_o_/_b_a_r just before it searches the standard directory _/_u_s_r_/_l_o_c_a_l_/_l_i_b_/_b_a_r. If a standard directory begins with the configured _p_r_e_f_i_x then the value of _p_r_e_f_i_x is replaced by GGCCCC__EEXXEECC__PPRREEFFIIXX when looking for header files. CCOOMMPPIILLEERR__PPAATTHH The value of CCOOMMPPIILLEERR__PPAATTHH is a colon-separated list of directo- ries, much like PPAATTHH. GCC tries the directories thus specified when searching for subprograms, if it cannot find the subprograms using GGCCCC__EEXXEECC__PPRREEFFIIXX. LLIIBBRRAARRYY__PPAATTHH The value of LLIIBBRRAARRYY__PPAATTHH is a colon-separated list of directories, much like PPAATTHH. When configured as a native compiler, GCC tries the directories thus specified when searching for special linker files, if it cannot find them using GGCCCC__EEXXEECC__PPRREEFFIIXX. Linking using GCC also uses these directories when searching for ordinary li- braries for the --ll option (but directories specified with --LL come first). LLAANNGG This variable is used to pass locale information to the compiler. One way in which this information is used is to determine the char- acter set to be used when character literals, string literals and comments are parsed in C and C++. When the compiler is configured to allow multibyte characters, the following values for LLAANNGG are recognized: CC--JJIISS Recognize JIS characters. CC--SSJJIISS Recognize SJIS characters. CC--EEUUCCJJPP Recognize EUCJP characters. If LLAANNGG is not defined, or if it has some other value, then the compiler uses "mblen" and "mbtowc" as defined by the default locale to recognize and translate multibyte characters. GGCCCC__EEXXTTRRAA__DDIIAAGGNNOOSSTTIICC__OOUUTTPPUUTT If GGCCCC__EEXXTTRRAA__DDIIAAGGNNOOSSTTIICC__OOUUTTPPUUTT is set to one of the following val- ues, then additional text will be emitted to stderr when fix-it hints are emitted. --ffddiiaaggnnoossttiiccss--ppaarrsseeaabbllee--ffiixxiittss and --ffnnoo--ddiiaagg-- nnoossttiiccss--ppaarrsseeaabbllee--ffiixxiittss take precedence over this environment variable. ffiixxiittss--vv11 Emit parseable fix-it hints, equivalent to --ffddiiaaggnnooss-- ttiiccss--ppaarrsseeaabbllee--ffiixxiittss. In particular, columns are expressed as a count of bytes, starting at byte 1 for the initial column. ffiixxiittss--vv22 As "fixits-v1", but columns are expressed as display columns, as per --ffddiiaaggnnoossttiiccss--ccoolluummnn--uunniitt==ddiissppllaayy. Some additional environment variables affect the behavior of the pre- processor. CCPPAATTHH CC__IINNCCLLUUDDEE__PPAATTHH CCPPLLUUSS__IINNCCLLUUDDEE__PPAATTHH OOBBJJCC__IINNCCLLUUDDEE__PPAATTHH Each variable's value is a list of directories separated by a spe- cial character, much like PPAATTHH, in which to look for header files. The special character, "PATH_SEPARATOR", is target-dependent and determined at GCC build time. For Microsoft Windows-based targets it is a semicolon, and for almost all other targets it is a colon. CCPPAATTHH specifies a list of directories to be searched as if speci- fied with --II, but after any paths given with --II options on the com- mand line. This environment variable is used regardless of which language is being preprocessed. The remaining environment variables apply only when preprocessing the particular language indicated. Each specifies a list of direc- tories to be searched as if specified with --iissyysstteemm, but after any paths given with --iissyysstteemm options on the command line. In all these variables, an empty element instructs the compiler to search its current working directory. Empty elements can appear at the beginning or end of a path. For instance, if the value of CCPPAATTHH is ":/special/include", that has the same effect as --II.. --II//ssppeecciiaall//iinncclluuddee. DDEEPPEENNDDEENNCCIIEESS__OOUUTTPPUUTT If this variable is set, its value specifies how to output depen- dencies for Make based on the non-system header files processed by the compiler. System header files are ignored in the dependency output. The value of DDEEPPEENNDDEENNCCIIEESS__OOUUTTPPUUTT can be just a file name, in which case the Make rules are written to that file, guessing the target name from the source file name. Or the value can have the form _f_i_l_e _t_a_r_g_e_t, in which case the rules are written to file _f_i_l_e using _t_a_r_g_e_t as the target name. In other words, this environment variable is equivalent to combin- ing the options --MMMM and --MMFF, with an optional --MMTT switch too. SSUUNNPPRROO__DDEEPPEENNDDEENNCCIIEESS This variable is the same as DDEEPPEENNDDEENNCCIIEESS__OOUUTTPPUUTT (see above), ex- cept that system header files are not ignored, so it implies --MM rather than --MMMM. However, the dependence on the main input file is omitted. SSOOUURRCCEE__DDAATTEE__EEPPOOCCHH If this variable is set, its value specifies a UNIX timestamp to be used in replacement of the current date and time in the "__DATE__" and "__TIME__" macros, so that the embedded timestamps become re- producible. The value of SSOOUURRCCEE__DDAATTEE__EEPPOOCCHH must be a UNIX timestamp, defined as the number of seconds (excluding leap seconds) since 01 Jan 1970 00:00:00 represented in ASCII; identical to the output of "date +%s" on GNU/Linux and other systems that support the %s extension in the "date" command. The value should be a known timestamp such as the last modification time of the source or package and it should be set by the build process. BBUUGGSS For instructions on reporting bugs, see . FFOOOOTTNNOOTTEESS 1. On some systems, ggcccc --sshhaarreedd needs to build supplementary stub code for constructors to work. On multi-libbed systems, ggcccc --sshhaarreedd must select the correct support libraries to link against. Failing to supply the correct flags may lead to subtle defects. Supplying them in cases where they are not necessary is innocuous. SSEEEE AALLSSOO _g_p_l(7), _g_f_d_l(7), _f_s_f_-_f_u_n_d_i_n_g(7), _c_p_p(1), _g_c_o_v(1), _a_s(1), _l_d(1), _g_d_b(1), _d_b_x(1) and the Info entries for _g_c_c, _c_p_p, _a_s, _l_d, _b_i_n_u_t_i_l_s and _g_d_b. AAUUTTHHOORR See the Info entry for ggcccc, or , for contributors to GCC. CCOOPPYYRRIIGGHHTT Copyright (c) 1988-2022 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with the Invariant Sections being "GNU General Public License" and "Funding Free Software", the Front-Cover texts being (a) (see below), and with the Back-Cover Texts being (b) (see below). A copy of the license is in- cluded in the _g_f_d_l(7) man page. (a) The FSF's Front-Cover Text is: A GNU Manual (b) The FSF's Back-Cover Text is: You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development. gcc-12 2022-08-19 GCC(1)