When you run the compiler, it usually performs all the necessary steps to convert source code into object code. For source files written in C or C++ the necessary steps are as follows:
Pre-processing
Compilation
Assembly
Linking
The "overall" options allow you to stop this process before the final step. For example, the -c option says not to run the linker. Then the output consists of object code files output by the assembler.
Other options are passed on to one stage 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.
See Section 1.3, for a summary of special options for compiling C++ programs.
The gcc program accepts options and file names as operands. Many options have multi-letter names; therefore multiple single-letter options may not be grouped: -dr is very different from -d -r.
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 -L more than once, the directories are searched in the order specified.
Many options have long names starting with -f or with -W : for example, -fforce-mem, -fstrength-reduce, -Wformat and so on. Most of these have both positive and negative forms; the negative form of -ffoo would be -fno-foo. This manual documents only one of these two forms, whichever one is not the default.
Here is a summary of all the options, grouped by type. Explanations are in the following sections.
See Section 1.2.
-c -S -E -o file -pipe -v -x language
See Section 1.4.
-ansi -fallow-single-precision -fcond-mismatch -fno-asm -fno-builtin -ffreestanding -fhosted -fsigned-bitfields -fsigned-char -funsigned-bitfields -funsigned-char -fwritable-strings -traditional -traditional-cpp -trigraphs
See Section 1.5.
-fall-virtual -fdollars-in-identifiers -felide-constructors -fenum-int-equiv -fexternal-templates -ffor-scope -fno-for-scope -fhandle-signatures -fmemoize-lookups -fname-mangling-version-n -fno-default-inline -fno-gnu-keywords -fnonnull-objects -fguiding-decls -foperator-names -fstrict-prototype -fthis-is-variable -ftemplate-depth-n -nostdinc++ -traditional +en
See Section 1.6.
-fsyntax-only -pedantic -pedantic-errors -w -W -Wall -Waggregate-return -Wbad-function-cast -Wcast-align -Wcast-qual -Wchar-subscript -Wcomment -Wconversion -Werror -Wformat -Wid-clash-len -Wimplicit -Wimplicit-int -Wimplicit-function-declarations -Wimport -Winline -Wlarger-than-len -Wmain -Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wno-import -Wold-style-cast -Woverloaded-virtual -Wparentheses -Wpointer-arith -Wredundant-decls -Wreorder -Wreturn-type i -Wshadow -Wsign-compare -Wstrict-prototypes -Wswitch -Wsynth -Wtemplate-debugging -Wtraditional -Wtrigraphs -Wundef -Wuninitialized -Wunused -Wwrite-strings
See Section 1.7.
-a -ax -dletters -fpretend-float -fprofile-arcs -ftest-coverage -g -glevel -gcoff -gdwarf -gdwarf-1 -gdwarf-1+ -gdwarf-2 -ggdb -gstabs -gstabs+ -gxcoff -gxcoff+ -p -pg -print-file-name=library -print-libgcc-file-name -print-prog-name=program -print-search-dirs -save-temps
See Section 1.8.
-fbranch-probabilities -fcaller-saves -fcse-follow-jumps -fcse-skip-blocks -fdelayed-branch -fexpensive-optimizations -ffast-math -ffloat-store -fforce-addr -fforce-mem -ffunction-sections -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
See Section 1.9.
-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
See Section 1.10.
-Wa,option
See Section 1.11.
object-file-name -llibrary -nostartfiles -nodefaultlibs -nostdlib -s -static -shared -symbolic -Wl,option -Xlinker option -u symbol
See Section 1.12.
-Bprefix -Idir -I- -Ldir -specs=file
See Section 1.13.1.
ERC32 Options -malign-jumps=num -malign-loops=num -malign-functions=num -mapp-regs -mepilogue -mfpu -mhard-float -mno-fpu -msoft-float -mno-app-regs -mno-epilogue -mno-unaligned-doubles -mv7 -mcba -mcca -mcda -mcpu=cpu