Here is a summary of all the options, grouped by type. Explanations are in the following sections.
-c -S -E -o file -pipe -v -x language
-ansi -fallow-single-precision -fcond-mismatch -fno-asm -fno-builtin -fsigned-bitfields -fsigned-char -funsigned-bitfields -funsigned-char -fwritable-strings -traditional -traditional-cpp -trigraphs
-fall-virtual -fdollars-in-identifiers -felide-constructors -fenum-int-equiv -fexternal-templates -ffor-scope -fno-for-scope -fhandle-signatures -fmemoize-lookups -fno-default-inline -fno-gnu-keywords -fnonnull-objects -foperator-names -fstrict-prototype -fthis-is-variable -nostdinc++ -traditional +en
-fsyntax-only -pedantic -pedantic-errors -w -W -Wall -Waggregate-return -Wbad-function-cast -Wcast-align -Wcast-qual -Wchar-subscript -Wcomment -Wconversion -Wenum-clash -Werror -Wformat -Wid-clash-len -Wimplicit -Wimport -Winline -Wlarger-than-len -Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wno-import -Woverloaded-virtual -Wparentheses -Wpointer-arith -Wredundant-decls -Wreorder -Wreturn-type -Wshadow -Wstrict-prototypes -Wswitch -Wsynth -Wtemplate-debugging -Wtraditional -Wtrigraphs -Wuninitialized -Wunused -Wwrite-strings
-a -dletters -fpretend-float -g -glevel -gcoff -gdwarf -gdwarf+ -ggdb -gstabs -gstabs+ -gxcoff -gxcoff+ -p -pg -print-file-name=library -print-libgcc-file-name -print-prog-name=program -print-search-dirs -save-temps
-fcaller-saves -fcse-follow-jumps -fcse-skip-blocks -fdelayed-branch -fexpensive-optimizations -ffast-math -ffloat-store -fforce-addr -fforce-mem -finline-functions -fkeep-inline-functions -fno-default-inline -fno-defer-pop -fno-function-cse -fno-inline -fno-peephole -fomit-frame-pointer -frerun-cse-after-loop -fschedule-insns -fschedule-insns2 -fstrength-reduce -fthread-jumps -funroll-all-loops -funroll-loops -O -O0 -O1 -O2 -O3
-Aquestion(answer) -C -dD -dM -dN -Dmacro[=defn] -E -H -idirafter dir -include file -imacros file -iprefix file -iwithprefix dir -iwithprefixbefore dir -isystem dir -M -MD -MM -MMD -MG -nostdinc -P -trigraphs -undef -Umacro -Wp,option
-Wa,option
object-file-name -llibrary -nostartfiles -nodefaultlibs -nostdlib -s -static -shared -symbolic -Wl,option -Xlinker option -u symbol
-Bprefix -Idir -I- -Ldir
-b machine -V version
M680x0 Options -m68000 -m68020 -m68020-40 -m68030 -m68040 -m68881 -mbitfield -mc68000 -mc68020 -mfpa -mnobitfield -mrtd -mshort -msoft-float VAX Options -mg -mgnu -munix SPARC Options -mapp-regs -mcypress -mepilogue -mflat -mfpu -mhard-float -mhard-quad-float -mno-app-regs -mno-flat -mno-fpu -mno-epilogue -mno-unaligned-doubles -msoft-float -msoft-quad-float -msparclite -msupersparc -munaligned-doubles -mv8 SPARC V9 compilers support the following options in addition to the above: -mmedlow -mmedany -mint32 -mint64 -mlong32 -mlong64 -mno-stack-bias -mstack-bias Convex Options -mc1 -mc2 -mc32 -mc34 -mc38 -margcount -mnoargcount -mlong32 -mlong64 -mvolatile-cache -mvolatile-nocache AMD29K Options -m29000 -m29050 -mbw -mnbw -mdw -mndw -mlarge -mnormal -msmall -mkernel-registers -mno-reuse-arg-regs -mno-stack-check -mno-storem-bug -mreuse-arg-regs -msoft-float -mstack-check -mstorem-bug -muser-registers ARM Options -mapcs -m2 -m3 -m6 -mbsd -mxopen -mno-symrename M88K Options -m88000 -m88100 -m88110 -mbig-pic -mcheck-zero-division -mhandle-large-shift -midentify-revision -mno-check-zero-division -mno-ocs-debug-info -mno-ocs-frame-position -mno-optimize-arg-area -mno-serialize-volatile -mno-underscores -mocs-debug-info -mocs-frame-position -moptimize-arg-area -mserialize-volatile -mshort-data-num -msvr3 -msvr4 -mtrap-large-shift -muse-div-instruction -mversion-03.00 -mwarn-passed-structs RS/6000 and PowerPC Options -mcpu=cpu type -mpower -mno-power -mpower2 -mno-power2 -mpowerpc -mno-powerpc -mpowerpc-gpopt -mno-powerpc-gpopt -mpowerpc-gfxopt -mno-powerpc-gfxopt -mnew-mnemonics -mno-new-mnemonics -mfull-toc -mminimal-toc -mno-fop-in-toc -mno-sum-in-toc -msoft-float -mhard-float -mmultiple -mno-multiple -mstring -mno-string -mbit-align -mno-bit-align -mstrict-align -mno-strict-align -mrelocatable -mno-relocatable -mtoc -mno-toc -mtraceback -mno-traceback -mlittle -mlittle-endian -mbig -mbig-endian -mcall-aix -mcall-sysv -mprototype RT Options -mcall-lib-mul -mfp-arg-in-fpregs -mfp-arg-in-gregs -mfull-fp-blocks -mhc-struct-return -min-line-mul -mminimum-fp-blocks -mnohc-struct-return MIPS Options -mabicalls -mcpu=cpu type -membedded-data -membedded-pic -mfp32 -mfp64 -mgas -mgp32 -mgp64 -mgpopt -mhalf-pic -mhard-float -mint64 -mips1 -mips2 -mips3 -mlong64 -mlong-calls -mmemcpy -mmips-as -mmips-tfile -mno-abicalls -mno-embedded-data -mno-embedded-pic -mno-gpopt -mno-long-calls -mno-memcpy -mno-mips-tfile -mno-rnames -mno-stats -mrnames -msoft-float -m4650 -msingle-float -mmad -mstats -EL -EB -G num -nocpp i386 Options -m486 -m386 -mieee-fp -mno-fancy-math-387 -mno-fp-ret-in-387 -msoft-float -msvr3-shlib -mno-wide-multiply -mrtd -malign-double -mreg-alloc=list -mregparm=num -malign-jumps=num -malign-loops=num -malign-functions=num HPPA Options -mdisable-fpregs -mdisable-indexing -mfast-indirect-calls -mgas -mjump-in-delay -mlong-millicode-calls -mno-disable-fpregs -mno-disable-indexing -mno-fast-indirect-calls -mno-gas -mno-jump-in-delay -mno-millicode-long-calls -mno-portable-runtime -mno-soft-float -msoft-float -mpa-risc-1-0 -mpa-risc-1-1 -mportable-runtime -mschedule=list Intel 960 Options -mcpu type -masm-compat -mclean-linkage -mcode-align -mcomplex-addr -mleaf-procedures -mic-compat -mic2.0-compat -mic3.0-compat -mintel-asm -mno-clean-linkage -mno-code-align -mno-complex-addr -mno-leaf-procedures -mno-old-align -mno-strict-align -mno-tail-call -mnumerics -mold-align -msoft-float -mstrict-align -mtail-call DEC Alpha Options -mfp-regs -mno-fp-regs -mno-soft-float -msoft-float Clipper Options -mc300 -mc400 H8/300 Options -mrelax -mh System V Options -Qy -Qn -YP,paths -Ym,dir
-fcall-saved-reg -fcall-used-reg -ffixed-reg -finhibit-size-directive -fno-common -fno-ident -fno-gnu-linker -fpcc-struct-return -fpic -fPIC -freg-struct-return -fshared-data -fshort-enums -fshort-double -fvolatile -fvolatile-global -fverbose-asm -fpack-struct +e0 +e1