跟老韩学Ubuntu Server 2204-gcc指令帮助手册第16小节

操作系统信息如下。

root@hanyw:~root@hanyw:~#"usertime","systemtime",,theoutputisappedtothenamedfile,anditlookslikethis:93170.120.01"usertime"andthe"systemtime"aremovedbeforetheprogramname,andtheoptionspassedtothe9320programaredisplayed,sothatonecanlatertellwhatfilewasbeingcompiled,[=file]9322Dumpthefinalinternalrepresentation(RTL)(oriffileis9323"."),thenameofthedumpfileisdeterminedbyapping".gkd"tothedumpbasename,[=opts]9325Ifnoerroroccursduringcompilation,runthecompilerasecondtime,addingoptsand9326-,,_COMPARE_DEBUG,ifdefined,non-emptyandnonzero,_COMPARE_DEBUGisdefinedtoastringstartingwithadash,thenitisusedfor9331opts,=,withtheequalsignbutwithoutopts,isequivalentto-fno-compare-debug,whichdisables9333thedumpingofthefinalrepresentationandthesecondcompilation,preventingevenGCC_COMPARE_,setGCC_COMPARE_DEBUGtosay9336-fcompare-debug-not-overridden,whichGCCrejectsasaninvalidoptioninanyactualcompilation(rather9337thanpreprocessing,assemblyorlinking).Togetjustawarning,settingGCC_COMPARE_DEBUGto9338-w%compilerforthesecondcompilationrequestedby-fcompare-debug,9341alongwithoptionstosilencewarnings,andomittingotheroptionsthatwouldcausethecohe".gk"additionalextensionduringthesecondcompilation,,itcausesthefirstcompilationtobeskipped,whi,ifleavingoutthisoptiongeneratesit,;ittakeseffectafterall9350otheroptionsareprocessed,anditdoessoonlyonce,ssignments,,=n9361Co,inLTOmode(via-flto).9368,mpilerprintsomestatisticsaboutpermantconsistencyofthe(estimated)nfortheprogram,,ifexplicitlyspecifiedanditisnotanexecutable,:9387***Oneormorequalifiers:"static","dynamic","bounded".9390Thequalifier"static"meansthatthefunctionmanipulatesthestackstatically:afixednumberofbytes9391areallocatedfortheframeonfunctionentryandreleasedonfunctionexit;"dynamic"meansthatthefunctionmanipulatesthestackdynamically:inadditiontothe9394staticallocationdescribedabove,stackadjustmentsaremadeinthebodyofthefunction,forexampleto9395push/"bounded"isalsopresent,theamountofthese9396adjustmentsisboundedatcompiletimeandthesecond,theamountoftheseadjustmentsisnotbounde++front,andtheinformationisgenerallyonlyusefultotheG++=cou:lower_bound1-upper_bound1[:lower_bound2-upper_bound2]_,with-fdbg-cnt=dce:2-4:10-11,tail_call:10,"dbg_cnt(dce)"returnstrueonlyforsecond,third,9409fourth,"dbg_cnt(tail_call)"=library9411Printthefullabsolutenameofthelibraryfilelibrarythatwouldbeusedwhenlinking---anddon',GCCdoesnotcompileorlinkanything;gtot_EXEC_;,andeachswitchstartswithan@insteadofthe-,eselectedmultilib,eused,thisisusuallyjust.,ifOS9423/lib64,../libor../lib32,orif9424OSlibrariesarepresentinlib/,multiarch,=program9428Like-print-file-name,=:9432gcc-nostdlibfiles`gcc-print-libgcc-file-name`9433-print-search-dirs9434Printthenameoftheconfiguredinstallationdirectoryandalistofprogramandlibrarydirectoriesgcc9435searches---anddon',cannotexeccpp0:swheregccexpects9438tofindthem,oryoucansettheenvironmentvariableGCC_EXEC_'tforgetthetrailing/.9440-print-sysrothe--sysrootoption,,rgetsysrootwhensearchingforheaders,orgiveanerrorifthecompiler9446isnotconfiguredwithsuchasuffix---anddon''stargetmachine(forexample,i686-pc-linux-gnu)---anddon'(forexample,3.0,6.3.0or7)---anddon'enumber(majorversion),twonumbersseparatedbyadot(majorandminorversion)or9453threenumbersseparatedbydots(major,minorandpatchlevelversion).9454-dumpfullversion9455Printthefullcompilerversion---anddon',major,'sbuilt-inspecs---anddon'tdoanythingelse.(ThisisusedwhenGCCitselfisbeing9459built.)9460Machine-DepentOptions9461EachtargetmachinesupportedbyGCCcanhaveitsownoptions---forexample,toallowyoutocompilefora9462particularprocessorvariantorABI,,specificoptions,ations:9468-mabi=,longintandpointersare32bits,andlp64forSysV-likedatamodelwhereintis32bits,;youmustcompileyourentireprogramwiththesameABI,_be-*-**-*butnotan9482aarch64_be-*-*====largeoptionisincompatiblewith-mabi=ilp32,-ngmemoryaccessesthatmaynotbealignedonanat99=guard9501-mstack-protector-guard-reg=reg9502-mstack-protector-guard-offset==regand9506-mstack-protector-guard-offset=offsetfurthermorespecifywhichsystemregistertouseasbaseregisterfor9507readingthecanary,=desc9510UseTLSdescriptorsas=traditional9513UsetraditionalTLSas=,24,32,48.aa9527,sablegenerationofaddition545"__builtin_speculation_safe_copy",at9549runtime,;ifnot,theywillusethe9550load/,-march==armv8-a+lse,==name9556Specifythenameofthetargetarchitectureand,optionally,=arch{+[no]feature}*.9558Thetablebelowsummarizesthepermissiblevaluesforarchandthefeaturesthattheyenablebydefault:9559archvalue:Architecture:Includesbydefault9560armv8-a:Armv8-A:+fp,+::armv8-a,+crc,+lse,+::::,+::,+flagm,+fp16fml,+::,+sb,+ssbs,+::,+bf16,+i8mm9567armv8-r:Armv8-R:armv8-r9568ThevaluenativeisavailableonnativeAArch64GNU/Lictureof9570thehostsystem,9571Thepermissiblevaluesforfeaturearelistedinthesub-sectiononaarch64-feature-modifiers,,-,cified,thecodeistunedtoperformwell9576=name9578Specifythenameo:generic,cortex-a35,cortex-a53,cortex-a55,cortex-a57,9580cortex-a72,cortex-a73,cortex-a75,cortex-a76,cortex-a76ae,cortex-a77,cortex-a65,cortex-a65ae,9581cortex-a34,cortex-a78,cortex-a78ae,cortex-a78c,ares,exynos-m1,emag,falkor,neoverse-512tvb,9582neoverse-e1,neoverse-n1,neoverse-n2,neoverse-v1,qdf24xx,saphira,phecda,xgene1,vulcan,octeontx,9583octeontx81,octeontx83,octeontx2,octeontx2t98,octeontx2t96octeontx2t93,octeontx2f95,octeontx2f95n,9584octeontx2f95mm,a64fx,thunderx,thunderxt88,thunderxt88p1,thunderxt81,tsv110,thunderxt83,9585thunderx2t99,thunderx3t110,zeus,,,,9586,,,cortex-r82,cortex-x1,ampere1,9587,,,,9589,ecoresthat(a)implementSVEand(b)9591,theoptiontellsGCCtotunefor9592Neoversecoresthatcanexecute4128-bitAdvancedSIMDarithmeticinstructionsacycleandthatcan9593executeanequivalentnumberofSVEarithmeticinstructionspercycle(2for256-bitSVE,4for128-bit9594SVE).ThisismoregeneralthantuningforaspecificcorelikeNe/=,-mcpu=or-march=arespecified,=name9602Specifythenameofthetargetprocessor,=cpu{+[no]feature}*,whereth05aarch64-feature-modifiers,,-,neratingassemblycode(asifby9608-march)andtodeterminethetargetprocessorforwhichtotuneforperformance(asifby-mtune).Where9609thisoptionisusedinconjunctionwith-marchor-mtune,t=neoverse-512tvbisspecialinthatitdoesnotrefertoaspecificcore,butinsteadreferstoall9612Neoversecoresthat(a)implementSVEand(b),-mcpu=neoverse-512tvbgeneratescodethatcanrunonaNeoverseV1core,,9615-mcpu=neoverse-512tvbtunescodeinthesamewayasfor-mtune==string9617Overridetuningdecisionsmadebytheback-inresponsetoa-mtune=,semantics,and9618acceptedvaluesfo==scope9629,9630whichdisablesreturnaddresssigning,non-leaf,whichenablespointersigningforfunctionswhicharenot9631leaffunctions,andall,=none|standard|pac-ret[+leaf+b-key]|,[+leaf]turnsonreturnaddresssigningto9637itsstandardlevel:signingfunctionsthatsavethereturnaddresstomemory(non-leaffunctionswill9638practicallyalwaysdothis)9640=opts9642Enablecompilerhardeningagainststraightlinespeculation(SLS).optsisacomma-separatedlistofthe9643followingoptions:9644retbr9645blr9646Inaddition,-mharden-sls=allenablesallSLShardeningwhile-mharden-sls==:"vector-lengthagnostic"outputthatworkswithanysizeof9650vectorregisterand"vector-lengthspecific"outputthatallowsGCCtomakeassumpti:scalable,128,256,9652512,1024=128exceptscalableshouldbereliedonforproduci=scalable,marchand-mcpucanbeanyofthefollowingandtheirinversesnofeature:9660====,butispassedontothe9681assembler,e=====,sha2,andsimd,,nofpimpliesnosimd,whichimplies9741nocrypto,evaEpiphany:9744-mhalf-reg-file9745Don'tallocateanyregisterintherange"r32""r63".,=num9751Setthecostofbranchestoroughlynum"simple"=sons,emitan"fsub",butcangetincorrectresultsinthepresenceofNaNs,orwhentwo9760differents,whichusesslower,butIEEE-compliant,=,avalueof8meansthattheeight9764bytesintherange"sp+0sp+7";compilingaprogram9766withadifferentstacfsetwouldgiveyoubettercode,butto9768actuallyuseadifferentstackoffsettobuildworkingprograms,itisrecommedtoconfigurethe9769toolchainwiththeappropriate--with-stack-offset=,assumeallcallsmightbebeyondtheoffsetrangeofthe"b"/9775"bl"instructions,andthereforeloadthefunctionaddressintoaregisterbeforeperforminga(otherwise9776direct),assumealldirectcallsareintherangeofthe"b"/"bl"9779instructions,=rtcanma:9788caller9789Anymodeatfunctionentryisvalid,andretainedorrestoredwhenthefunctionreturns,9791mightwanttoincorporateintodifferentprogramswithdifferentprevailingFPUmodes,andthe9792convenienceofbeingabletouseasingleobjectfileoutweighsthesizeandspeedoverheadforany9793extramodeswitchingthatmightbeneeded,comparedwithithtruncating()9797,,=caller9803-mno-split-lohi9804-mno-postinc9805-mno-postmodify9806Codegenerationtweaksthatdisable,respectively,splittingof32-bitloads,generationofpost-increment9807addresses,,-mpost-inc,,=,eventhoughmanylibraryfunctioninterfacesareunaffectediftheydon'tuseSIMDvector9815modesinplacesthataffectsizeand/,,whic,whichspecifyuseofthatregisterasafixed9822register,andnone,=gpu9826-mtune=(gfx803).9830gfx9009831CompileforGCN5Vega10devices(gfx900).9832gfx9069833CompileforGCN5Vega20devices(gfx906).9834-msram-ecc=on9835-msram-ecc=off9836-msram-ecc=any9837CompilebinariessuitablefordeviceswiththeSRAM-ECCfeatureenabled,disabled,,=bytes9841SpecifyhowmanybytesofstackspacewillberequestedforeachGPUthread(wave-front).,antforwhichcodeisbeingcompiled:9850-=ARC601or-mcpu=_=cpu9856Setarchitecturetype,registerusage,:-mA6,-:-:-mA7,-=__fpus9874Compile_fpuda9876CompileforARCEM4DMIPSC__norm9885CompileforARC600CPUwith"norm"_mul32x169887CompileforARC600CPUwith"norm"_mul649889CompileforARC600CPUwith"norm"and"mul64"-_norm9891CompileforARC601CPUwith"norm"_mul32x169893CompileforARC601CPUwith"norm"_mul649895CompileforARC601CPUwith"norm"and"mul64"-_mini9899Coructions,,"lr"and"sr""divaw","adds","subs",and"sat16"="mpy"-"mul64"and"mulu64"="norm"=ructions,,=;,andthisdefaultcanoverriddenbyFPXoptions;-mspfp,-mspfp-compact,or-mspfp-fast9928forsingleprecision,and-mdpfp,-mdpfp-compact,"swap"/storec"div"and"rem"/==:994509946,:"mpyw"and"mpyuw".995029951wlh1995232x32multiplier,fullypipelined(1stage).Thefollowinginstructionsareadditionallyenabled:9953"mpy","mpyu","mpym","mpymu",and"mpy_s".995439955wlh2995632x32multiplier,fullypipelined(2stages).Thefollowinginstructionsareadditionallyenabled:9957"mpy","mpyu","mpym","mpymu",and"mpy_s".995849959wlh39960Two16x16multipliers,blocking,:9961"mpy","mpyu","mpym","mpymu",and"mpy_s".996259963wlh49964One16x16multiplier,blocking,:9965"mpy","mpyu","mpym","mpymu",and"mpy_s".996669967wlh59968One32x4multiplier,blocking,:"mpy",9969"mpyu","mpym","mpymu",and"mpy_s".997079971plus___=fpu9981Enables:9983fpus9984En_div9993Enablessupportfordouble-precisionfloating-poi,square-root,_fma9997Enablessupportfordouble-precisionfloating-poi_all10001Enablessupportfordouble-precisionfloating-poin_div10005Enablessupportforsingle-precisionfloating-point,_div10007Enablessupportfordouble-precisionfloating-point,__fma10010Enablessupportforsingle-_fma10012Enablessupportfordouble-__all10015Enabl_all10017Enablessupportf=register-range,blink,lp_count10020Specifiesgeneral-purposesregistersthattheprocessorautomaticallysaves/"r0",theupperlimitis"fp"_=number10025Specifiesthenumber,8,16,=width10030Specifythewidthofthe"lp_count",16,20,24,28,thecompilerdoesnotattemptto10032transformloopsinyourprogramtousethezero-delayloopmechanismunlessitisknownthatthe"lp_count"10033,thecompilerandrun-10034"__ARC_LPC_WIDTH__""__ARC_RF16__""bi"or"bih","__Xdsp_packa"."__Xdvbf"./"__Xlock".10051-"__Xxmac_d16"."__Xxmac_24"."__Xrtsc"."__Xswape".10061-mtelephony10062Passeddowntothe"__Xtelephony"."__Xxy".10066Thefollowingoptionscontrolhowtheassemblycodeisannotated:10067-:10072-marclinux10073Passedthroughtothelinker,tospecifyuseofthe"arclinux""arc-linux-uclibc"and"arceb-linux-uclibc"_prof10077Passedthroughtothelinker,tospecifyuseofthe"arclinux_prof""arc-linux-uclibc"and"arceb-linux-uclibc":10081-mlong-calls10082Generatecallsasregisterindirectcalls,'tuselessthan25-bitaddressingrangeforcalls,whichistheo,toallowuseofthe1008625-bitrange,"arc-linux-uclibc"and"arceb-linux-uclibc",or8whenwehavedoubleload/"arc-linux-uclibc"and10094"arceb-linux-uclibc":10100-/_reorgtogeneratecompare-and-branch("brcc")10108"casesi",rs,literalsizes,instructionlengths,10117andthesupportforconditionalexecution,thetarget-indepentpasstogenerateconditionalexecutionis10118oftenlacking,sotheARCporthaskeptaspecialpassaroundthattriestofindmoreconditionalexecution10119generationopportunitiesafterregisterallocation,branchshortening,,butnotalways,improvesperformanceandcodesize,atthecostofextra10121compilationtime,leoffsetrangebecausetheyareconditionalized,"cbranchsi""adddi3"and"subdi3"atRTLgenerationtimeinto"","adc"0130storesexist,,sobydefaultthecompileruses10133standardreload(-mno-lra).10134-mlra-priority-none10135Don'orr0..r3/r12..forr0..r3/r12..(using-Os),prologuesandepiloguesthathavetosaveorrestorealargenumber10142ofregistersareoftenshortenedbyusingcalltoaspecialfunctioninlibgcc;,and/orcauselinkingissueswhenlinkingina10144nonstandardway,"enter"and"leave"=level10158Fine-:101600,,optionaldataalignmentisdropped,,=cpu10167Setinstructionschedulingparametersforcpu,overridinganyimpliedby-mcpu=.10168=num10182Costtoassumeforamultiplyinstruction,=,10185brancheswithoutfilleddelayslotarepreferablyemittedunalignedandlong,unlessprofilingindicate(REG_BR_PROB_BASE/2),10187,butarenowdeprecatedandwillberemovedin10189afuturerelease:10190-"arceb-elf32"and"arceb-linux-uclibc"targets,"arc-elf32"and"arc-linux-uclibc"targets,_____2410211___=cpu10219Valuesarc600,arc601,arc700andarc700-xmacforcpuarereplacedbyARC600,ARC601,=:10225-mabi=:apcs-gnu,atpcs,aapcs,ARMProcedureCallStandardforallfunctions,ev,on10237pre-v5architectures,,sinthefunctionprologue,orthemergingofthoseinstructionwith10242theinstructionsinthefunction'ctions(orinfactoneofachoicefromasmallsetofdifferentfunctionprologues),andthis10244informationca=:soft,instructions,e;youmustcompileyourentireprogramwiththesameABI,ianmode;,=name[+extension]10271=:armv4t,armv5t,armv5te,armv6,armv6j,armv6k,armv6kz,armv6t2,armv6z,armv6zk,10275armv7,armv7-a,armv7ve,armv8-a,,,,,,,10276armv7-r,armv8-r,armv6-m,armv6s-m,armv7-m,armv7e-m,,,,,thefollowingarchitectures,whichlacksupportfortheThumbexecutionstate,arerecognized10279butsupportisdeprecated:+,the+cryptoextension10283willalwaysenablethe+eprefixedwith+no:theseextensionsdisablethespecifiedoptionanda,-march=armv7-a+simd+nofp+vfpv4isequivalenttowriting-march=armv7-a+vfpv4sincethe+simd10287optionisentirelydisabledbythe+,buthaveaneffectthatisdepentuponthearchitectureto