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 1.2 or
+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
@gccoptlist{-c -S -E -o @var{file} -combine -no-canonical-prefixes @gol
-pipe -pass-exit-codes @gol
-x @var{language} -v -### --help@r{[}=@var{class}@r{[},@dots{}@r{]]} --target-help @gol
---version -wrapper@@@var{file} -fplugin=@var{file} -fplugin-arg-@var{name}=@var{arg}}
+--version -wrapper@@@var{file} -fplugin=@var{file} -fplugin-arg-@var{name}=@var{arg} @gol
+-fdump-ada-spec@r{[}-slim@r{]}}
@item C Language Options
@xref{C Dialect Options,,Options Controlling C Dialect}.
-fno-implicit-templates @gol
-fno-implicit-inline-templates @gol
-fno-implement-inlines -fms-extensions @gol
--fno-nonansi-builtins -fno-operator-names @gol
+-fno-nonansi-builtins -fnothrow-opt -fno-operator-names @gol
-fno-optional-diags -fpermissive @gol
-fno-pretty-templates @gol
-frepo -fno-rtti -fstats -ftemplate-depth=@var{n} @gol
-fno-default-inline -fvisibility-inlines-hidden @gol
-fvisibility-ms-compat @gol
-Wabi -Wconversion-null -Wctor-dtor-privacy @gol
--Wnon-virtual-dtor -Wreorder @gol
+-Wnoexcept -Wnon-virtual-dtor -Wreorder @gol
-Weffc++ -Wstrict-null-sentinel @gol
-Wno-non-template-friend -Wold-style-cast @gol
-Woverloaded-virtual -Wno-pmf-conversions @gol
-Wno-attributes -Wno-builtin-macro-redefined @gol
-Wc++-compat -Wc++0x-compat -Wcast-align -Wcast-qual @gol
-Wchar-subscripts -Wclobbered -Wcomment @gol
--Wconversion -Wcoverage-mismatch -Wno-deprecated @gol
+-Wconversion -Wcoverage-mismatch -Wcpp -Wno-deprecated @gol
-Wno-deprecated-declarations -Wdisabled-optimization @gol
-Wno-div-by-zero -Wempty-body -Wenum-compare -Wno-endif-labels @gol
-Werror -Werror=* @gol
-Wlogical-op -Wlong-long @gol
-Wmain -Wmissing-braces -Wmissing-field-initializers @gol
-Wmissing-format-attribute -Wmissing-include-dirs @gol
--Wmissing-noreturn -Wno-mudflap @gol
+-Wno-mudflap @gol
-Wno-multichar -Wnonnull -Wno-overflow @gol
-Woverlength-strings -Wpacked -Wpacked-bitfield-compat -Wpadded @gol
-Wparentheses -Wpedantic-ms-format -Wno-pedantic-ms-format @gol
-Wsign-compare -Wsign-conversion -Wstack-protector @gol
-Wstrict-aliasing -Wstrict-aliasing=n @gol
-Wstrict-overflow -Wstrict-overflow=@var{n} @gol
+-Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{]} @gol
-Wswitch -Wswitch-default -Wswitch-enum -Wsync-nand @gol
--Wsystem-headers -Wtrigraphs -Wtype-limits -Wundef -Wuninitialized @gol
--Wunknown-pragmas -Wno-pragmas @gol
+-Wsystem-headers -Wtrampolines -Wtrigraphs -Wtype-limits -Wundef @gol
+-Wuninitialized -Wunknown-pragmas -Wno-pragmas @gol
-Wunsuffixed-float-constants -Wunused -Wunused-function @gol
-Wunused-label -Wunused-parameter -Wno-unused-result -Wunused-value -Wunused-variable @gol
--Wvariadic-macros -Wvla @gol
+-Wunused-but-set-parameter -Wunused-but-set-variable -Wvariadic-macros -Wvla @gol
-Wvolatile-register-var -Wwrite-strings}
@item C and Objective-C-only Warning Options
-fearly-inlining -fipa-sra -fexpensive-optimizations -ffast-math @gol
-ffinite-math-only -ffloat-store -fexcess-precision=@var{style} @gol
-fforward-propagate -ffunction-sections @gol
--fgcse -fgcse-after-reload -fgcse-las -fgcse-lm @gol
+-fgcse -fgcse-after-reload -fgcse-las -fgcse-lm -fgraphite-identity @gol
-fgcse-sm -fif-conversion -fif-conversion2 -findirect-inlining @gol
-finline-functions -finline-functions-called-once -finline-limit=@var{n} @gol
-finline-small-functions -fipa-cp -fipa-cp-clone -fipa-matrix-reorg -fipa-pta @gol
--fipa-pure-const -fipa-reference -fipa-struct-reorg @gol
--fipa-type-escape -fira-algorithm=@var{algorithm} @gol
+-fipa-profile -fipa-pure-const -fipa-reference -fipa-struct-reorg @gol
+-fira-algorithm=@var{algorithm} @gol
-fira-region=@var{region} -fira-coalesce @gol
-fira-loop-pressure -fno-ira-share-save-slots @gol
-fno-ira-share-spill-slots -fira-verbose=@var{n} @gol
-fivopts -fkeep-inline-functions -fkeep-static-consts @gol
--floop-block -floop-interchange -floop-strip-mine -fgraphite-identity @gol
+-floop-block -floop-interchange -floop-strip-mine @gol
-floop-parallelize-all -flto -flto-compression-level -flto-report -fltrans @gol
-fltrans-output-list -fmerge-all-constants -fmerge-constants -fmodulo-sched @gol
-fmodulo-sched-allow-regmoves -fmove-loop-invariants -fmudflap @gol
-fno-sched-interblock -fno-sched-spec -fno-signed-zeros @gol
-fno-toplevel-reorder -fno-trapping-math -fno-zero-initialized-in-bss @gol
-fomit-frame-pointer -foptimize-register-move -foptimize-sibling-calls @gol
--fpeel-loops -fpredictive-commoning -fprefetch-loop-arrays @gol
+-fpartial-inlining -fpeel-loops -fpredictive-commoning -fprefetch-loop-arrays @gol
-fprofile-correction -fprofile-dir=@var{path} -fprofile-generate @gol
-fprofile-generate=@var{path} @gol
-fprofile-use -fprofile-use=@var{path} -fprofile-values @gol
-fsplit-wide-types -fstack-protector -fstack-protector-all @gol
-fstrict-aliasing -fstrict-overflow -fthread-jumps -ftracer @gol
-ftree-builtin-call-dce -ftree-ccp -ftree-ch -ftree-copy-prop @gol
--ftree-copyrename -ftree-dce @gol
--ftree-dominator-opts -ftree-dse -ftree-forwprop -ftree-fre -ftree-loop-im @gol
--ftree-phiprop -ftree-loop-distribution @gol
+-ftree-copyrename -ftree-dce -ftree-dominator-opts -ftree-dse @gol
+-ftree-forwprop -ftree-fre -ftree-loop-if-convert -ftree-loop-im @gol
+-ftree-phiprop -ftree-loop-distribution -ftree-loop-distribute-patterns @gol
-ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol
-ftree-parallelize-loops=@var{n} -ftree-pre -ftree-pta -ftree-reassoc @gol
-ftree-sink -ftree-sra -ftree-switch-conversion @gol
-funit-at-a-time -funroll-all-loops -funroll-loops @gol
-funsafe-loop-optimizations -funsafe-math-optimizations -funswitch-loops @gol
-fvariable-expansion-in-unroller -fvect-cost-model -fvpt -fweb @gol
--fwhole-program -fwhopr -fwpa -fuse-linker-plugin @gol
+-fwhole-program -fwhopr[=@var{n}] -fwpa -fuse-linker-plugin @gol
--param @var{name}=@var{value}
--O -O0 -O1 -O2 -O3 -Os}
+-O -O0 -O1 -O2 -O3 -Os -Ofast}
@item Preprocessor Options
@xref{Preprocessor Options,,Options Controlling the Preprocessor}.
@item Directory Options
@xref{Directory Options,,Options for Directory Search}.
-@gccoptlist{-B@var{prefix} -I@var{dir} -iquote@var{dir} -L@var{dir}
--specs=@var{file} -I- --sysroot=@var{dir}}
-
-@item Target Options
-@c I wrote this xref this way to avoid overfull hbox. -- rms
-@xref{Target Options}.
-@gccoptlist{-V @var{version} -b @var{machine}}
+@gccoptlist{-B@var{prefix} -I@var{dir} -iplugindir=@var{dir}}
+-iquote@var{dir} -L@var{dir} -specs=@var{file} -I-
+--sysroot=@var{dir}
@item Machine Dependent Options
@xref{Submodel Options,,Hardware Models and Configurations}.
-mcpu=@var{cpu}}
@emph{GNU/Linux Options}
-@gccoptlist{-muclibc}
+@gccoptlist{-mglibc -muclibc -mbionic -mandroid @gol
+-tno-android-cc -tno-android-ld}
@emph{H8/300 Options}
@gccoptlist{-mrelax -mh -ms -mn -mint32 -malign-300}
-mincoming-stack-boundary=@var{num}
-mcld -mcx16 -msahf -mmovbe -mcrc32 -mrecip @gol
-mmmx -msse -msse2 -msse3 -mssse3 -msse4.1 -msse4.2 -msse4 -mavx @gol
--maes -mpclmul -mfused-madd @gol
+-maes -mpclmul -mfsgsbase -mrdrnd -mf16c -mfused-madd @gol
-msse4a -m3dnow -mpopcnt -mabm -mfma4 -mxop -mlwp @gol
-mthreads -mno-align-stringops -minline-all-stringops @gol
-minline-stringops-dynamically -mstringop-strategy=@var{alg} @gol
-momit-leaf-frame-pointer -mno-red-zone -mno-tls-direct-seg-refs @gol
-mcmodel=@var{code-model} -mabi=@var{name} @gol
-m32 -m64 -mlarge-data-threshold=@var{num} @gol
--msse2avx}
+-msse2avx -mfentry}
@emph{IA-64 Options}
@gccoptlist{-mbig-endian -mlittle-endian -mgnu-as -mgnu-ld -mno-pic @gol
@emph{RS/6000 and PowerPC Options}
@gccoptlist{-mcpu=@var{cpu-type} @gol
-mtune=@var{cpu-type} @gol
+-mcmodel=@var{code-model} @gol
-mpower -mno-power -mpower2 -mno-power2 @gol
-mpowerpc -mpowerpc64 -mno-powerpc @gol
-maltivec -mno-altivec @gol
-mcall-sysv -mcall-netbsd @gol
-maix-struct-return -msvr4-struct-return @gol
-mabi=@var{abi-type} -msecure-plt -mbss-plt @gol
+-mblock-move-inline-limit=@var{num} @gol
-misel -mno-isel @gol
-misel=yes -misel=no @gol
-mspe -mno-spe @gol
-mfloat-gprs=yes -mfloat-gprs=no -mfloat-gprs=single -mfloat-gprs=double @gol
-mprototype -mno-prototype @gol
-msim -mmvme -mads -myellowknife -memb -msdata @gol
--msdata=@var{opt} -mvxworks -G @var{num} -pthread}
+-msdata=@var{opt} -mvxworks -G @var{num} -pthread @gol
+-mrecip -mrecip=@var{opt} -mno-recip -mrecip-precision -mno-recip-precision}
@emph{RX Options}
@gccoptlist{-m64bit-doubles -m32bit-doubles -fpu -nofpu@gol
--mcpu= -patch=@gol
+-mcpu=@gol
-mbig-endian-data -mlittle-endian-data @gol
-msmall-data @gol
-msim -mno-sim@gol
-mprefergot -musermode -multcost=@var{number} -mdiv=@var{strategy} @gol
-mdivsi3_libfunc=@var{name} -mfixed-range=@var{register-range} @gol
-madjust-unroll -mindexed-addressing -mgettrcost=@var{number} -mpt-fixed @gol
--minvalid-symbols}
+-maccumulate-outgoing-args -minvalid-symbols}
@emph{SPARC Options}
@gccoptlist{-mcpu=@var{cpu-type} @gol
-mtda=@var{n} -msda=@var{n} -mzda=@var{n} @gol
-mapp-regs -mno-app-regs @gol
-mdisable-callt -mno-disable-callt @gol
+-mv850e2v3 @gol
+-mv850e2 @gol
-mv850e1 @gol
-mv850e @gol
-mv850 -mbig-switch}
@emph{Xtensa Options}
@gccoptlist{-mconst16 -mno-const16 @gol
-mfused-madd -mno-fused-madd @gol
+-mforce-no-pic @gol
-mserialize-volatile -mno-serialize-volatile @gol
-mtext-section-literals -mno-text-section-literals @gol
-mtarget-align -mno-target-align @gol
-fshort-double -fshort-wchar @gol
-fverbose-asm -fpack-struct[=@var{n}] -fstack-check @gol
-fstack-limit-register=@var{reg} -fstack-limit-symbol=@var{sym} @gol
--fno-stack-limit -fargument-alias -fargument-noalias @gol
--fargument-noalias-global -fargument-noalias-anything @gol
+-fno-stack-limit @gol
-fleading-underscore -ftls-model=@var{model} @gol
-ftrapv -fwrapv -fbounds-check @gol
-fvisibility}
@item @var{file}.h
C, C++, Objective-C or Objective-C++ header file to be turned into a
-precompiled header.
+precompiled header (default), or C, C++ header file to be turned into an
+Ada spec (via the @option{-fdump-ada-spec} switch).
@item @var{file}.cc
@itemx @var{file}.cp
@itemx @var{file}.HPP
@itemx @var{file}.h++
@itemx @var{file}.tcc
-C++ header file to be turned into a precompiled header.
+C++ header file to be turned into a precompiled header or Ada spec.
@item @var{file}.f
@itemx @var{file}.for
@item -###
@opindex ###
-Like @option{-v} except the commands are not executed and all command
-arguments are quoted. This is useful for shell scripts to capture the
-driver-generated command lines.
+Like @option{-v} except the commands are not executed and arguments
+are quoted unless they contain only alphanumeric characters or @code{./-_}.
+This is useful for shell scripts to capture the driver-generated command lines.
@item -pipe
@opindex pipe
Define an argument called @var{key} with a value of @var{value}
for the plugin called @var{name}.
+@item -fdump-ada-spec@r{[}-slim@r{]}
+For C and C++ source and include files, generate corresponding Ada
+specs. @xref{Generating Ada Bindings for C and C++ headers,,, gnat_ugn,
+GNAT User's Guide}, which provides detailed documentation on this feature.
+
@include @value{srcdir}/../libiberty/at-file.texi
@end table
@w{@uref{http://gcc.gnu.org/c99status.html}} for more information. The
names @samp{c9x} and @samp{iso9899:199x} are deprecated.
+@item c1x
+ISO C1X, the draft of the next revision of the ISO C standard.
+Support is limited and experimental and features enabled by this
+option may be changed or removed if changed in or removed from the
+standard draft.
+
@item gnu90
@itemx gnu89
GNU dialect of ISO C90 (including some C99 features). This
GNU dialect of ISO C99. When ISO C99 is fully implemented in GCC,
this will become the default. The name @samp{gnu9x} is deprecated.
+@item gnu1x
+GNU dialect of ISO C1X. Support is limited and experimental and
+features enabled by this option may be changed or removed if changed
+in or removed from the standard draft.
+
@item c++98
The 1998 ISO C++ standard plus amendments. Same as @option{-ansi} for
C++ code.
ANSI/ISO C@. These include @code{ffs}, @code{alloca}, @code{_exit},
@code{index}, @code{bzero}, @code{conjf}, and other related functions.
+@item -fnothrow-opt
+@opindex fnothrow-opt
+Treat a @code{throw()} exception specification as though it were a
+@code{noexcept} 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 will actually make the
+function smaller because 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 will result in a call
+to @code{terminate} rather than @code{unexpected}.
+
@item -fno-operator-names
@opindex fno-operator-names
Do not treat the operator name keywords @code{and}, @code{bitand},
Emit statistics about front-end processing at the end of the compilation.
This information is generally only useful to the G++ development team.
+@item -fstrict-enums
+@opindex fstrict-enums
+Allow the compiler to optimize using the assumption that a value of
+enumeration type can only be one of the values of the enumeration (as
+defined in the C++ standard; basically, a value which 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 enumeration type.
+
@item -ftemplate-depth=@var{n}
@opindex ftemplate-depth
Set the maximum instantiation depth for template classes to @var{n}.
destructors in that class are private, and it has neither friends nor
public static member functions.
+@item -Wnoexcept @r{(C++ and Objective-C++ only)}
+@opindex Wnoexcept
+@opindex Wno-noexcept
+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. @samp{throw()} or @samp{noexcept}) but is known by
+the compiler to never throw an exception.
+
@item -Wnon-virtual-dtor @r{(C++ and Objective-C++ only)}
@opindex Wnon-virtual-dtor
@opindex Wno-non-virtual-dtor
If a source file was changed between @option{-fprofile-gen} and
@option{-fprofile-use}, the files with the profile feedback can fail
to match the source file and GCC can not use the profile feedback
-information. By default, GCC emits an error message in this case.
-The option @option{-Wcoverage-mismatch} emits a warning instead of an
-error. GCC does not use appropriate feedback profiles, so using this
-option can result in poorly optimized code. This option is useful
-only in the case of very minor changes such as bug fixes to an
-existing code-base.
+information. By default, this warning is enabled and is treated as an
+error. @option{-Wno-coverage-mismatch} can be used to disable the
+warning or @option{-Wno-error=coverage-mismatch} can be used to
+disable the error. Disable the error for this warning can result in
+poorly optimized code, so disabling the error is useful only in the
+case of very minor changes such as bug fixes to an existing code-base.
+Completely disabling the warning is not recommended.
@end table
language-specific options also refer to @ref{C++ Dialect Options} and
@ref{Objective-C and Objective-C++ Dialect Options}.
+When an unrecognized warning label is requested (e.g.,
+@option{-Wunknown-warning}), GCC will emit a diagnostic stating
+that the option is not recognized. However, if the @samp{-Wno-} form
+is used, the behavior is slightly different: No diagnostic will be
+produced for @option{-Wno-unknown-warning} unless other diagnostics
+are being produced. This allows the use of new @option{-Wno-} options
+with old compilers, but if something goes wrong, the compiler will
+warn that an unrecognized option was used.
+
@table @gcctabopt
@item -pedantic
@opindex pedantic
-Wc++0x-compat @gol
-Wchar-subscripts @gol
-Wenum-compare @r{(in C/Objc; this is on by default in C++)} @gol
--Wimplicit-int @gol
--Wimplicit-function-declaration @gol
+-Wimplicit-int @r{(C and Objective-C only)} @gol
+-Wimplicit-function-declaration @r{(C and Objective-C only)} @gol
-Wcomment @gol
-Wformat @gol
-Wmain @r{(only for C/ObjC and unless} @option{-ffreestanding}@r{)} @gol
-Wsign-compare @gol
-Wtype-limits @gol
-Wuninitialized @gol
--Wunused-parameter @r{(only with} @option{-Wunused} @r{or} @option{-Wall}@r{)} @gol
+-Wunused-parameter @r{(only with} @option{-Wunused} @r{or} @option{-Wall}@r{)} @gol
+-Wunused-but-set-parameter @r{(only with} @option{-Wunused} @r{or} @option{-Wall}@r{)} @gol
}
The option @option{-Wextra} also prints warning messages for the
comment, or whenever a Backslash-Newline appears in a @samp{//} comment.
This warning is enabled by @option{-Wall}.
+@item -Wno-cpp \
+@r{(C, Objective-C, C++, Objective-C++ and Fortran only)}
+
+Suppress warning messages emitted by @code{#warning} directives.
+
@item -Wformat
@opindex Wformat
@opindex Wno-format
@option{-pedantic-errors}. This warning is also enabled by
@option{-Wall}.
-@item -Wimplicit
+@item -Wimplicit @r{(C and Objective-C only)}
@opindex Wimplicit
@opindex Wno-implicit
Same as @option{-Wimplicit-int} and @option{-Wimplicit-function-declaration}.
@end group
@end smallexample
+Also warn for dangerous uses of the
+?: with omitted middle operand GNU extension. When the condition
+in the ?: operator is a boolean expression the omitted value will
+be always 1. Often the user expects it to be a value computed
+inside the conditional expression instead.
+
This warning is enabled by @option{-Wall}.
@item -Wsequence-point
the program (trigraphs within comments are not warned about).
This warning is enabled by @option{-Wall}.
+@item -Wunused-but-set-parameter
+@opindex Wunused-but-set-parameter
+@opindex Wno-unused-but-set-parameter
+Warn whenever a function parameter is assigned to, but otherwise unused
+(aside from its declaration).
+
+To suppress this warning use the @samp{unused} attribute
+(@pxref{Variable Attributes}).
+
+This warning is also enabled by @option{-Wunused} together with
+@option{-Wextra}.
+
+@item -Wunused-but-set-variable
+@opindex Wunused-but-set-variable
+@opindex Wno-unused-but-set-variable
+Warn whenever a local variable is assigned to, but otherwise unused
+(aside from its declaration).
+This warning is enabled by @option{-Wall}.
+
+To suppress this warning use the @samp{unused} attribute
+(@pxref{Variable Attributes}).
+
+This warning is also enabled by @option{-Wunused}, which is enabled
+by @option{-Wall}.
+
@item -Wunused-function
@opindex Wunused-function
@opindex Wno-unused-function
false positives.
@end table
+@item -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{]}
+@opindex Wsuggest-attribute=
+@opindex Wno-suggest-attribute=
+Warn for cases where adding an attribute may be beneficial. The
+attributes currently supported are listed below.
+
+@table @gcctabopt
+@item -Wsuggest-attribute=pure
+@itemx -Wsuggest-attribute=const
+@itemx -Wsuggest-attribute=noreturn
+@opindex Wsuggest-attribute=pure
+@opindex Wno-suggest-attribute=pure
+@opindex Wsuggest-attribute=const
+@opindex Wno-suggest-attribute=const
+@opindex Wsuggest-attribute=noreturn
+@opindex Wno-suggest-attribute=noreturn
+
+Warn about functions which might be candidates for attributes
+@code{pure}, @code{const} or @code{noreturn}. The compiler only warns for
+functions visible in other compilation units or (in the case of @code{pure} and
+@code{const}) if it cannot prove that the function returns normally. A function
+returns normally if it doesn't contain an infinite loop nor returns abnormally
+by throwing, calling @code{abort()} or trapping. This analysis requires option
+@option{-fipa-pure-const}, which is enabled by default at @option{-O} and
+higher. Higher optimization levels improve the accuracy of the analysis.
+@end table
+
@item -Warray-bounds
@opindex Wno-array-bounds
@opindex Warray-bounds
This option is only active when @option{-ftree-vrp} is active
-(default for -O2 and above). It warns about subscripts to arrays
+(default for @option{-O2} and above). It warns about subscripts to arrays
that are always out of bounds. This warning is enabled by @option{-Wall}.
@item -Wno-div-by-zero
option will @emph{not} warn about unknown pragmas in system
headers---for that, @option{-Wunknown-pragmas} must also be used.
+@item -Wtrampolines
+@opindex Wtrampolines
+@opindex Wno-trampolines
+ 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 special treatment. But,
+ for most targets, it is made up of code and thus requires the stack
+ to be made executable in order for the program to work properly.
+
@item -Wfloat-equal
@opindex Wfloat-equal
@opindex Wno-float-equal
@item -Wshadow
@opindex Wshadow
@opindex Wno-shadow
-Warn whenever a local variable shadows another local variable, parameter or
-global variable or whenever a built-in function is shadowed.
+Warn whenever a local variable or type declaration shadows another variable,
+parameter, type, or class member (in C++), or whenever a built-in function
+is shadowed. Note that in C++, the compiler will not warn if a local variable
+shadows a struct/class/enum, but will warn if it shadows an explicit typedef.
@item -Wlarger-than=@var{len}
@opindex Wlarger-than=@var{len}
This warning is included in @option{-Wextra}. To get other @option{-Wextra}
warnings without this one, use @samp{-Wextra -Wno-missing-field-initializers}.
-@item -Wmissing-noreturn
-@opindex Wmissing-noreturn
-@opindex Wno-missing-noreturn
-Warn about functions which might be candidates for attribute @code{noreturn}.
-Note these are only possible candidates, not absolute ones. Care should
-be taken to manually verify functions actually do not ever return before
-adding the @code{noreturn} attribute, otherwise subtle code generation
-bugs could be introduced. You will not get a warning for @code{main} in
-hosted C environments.
-
@item -Wmissing-format-attribute
@opindex Wmissing-format-attribute
@opindex Wno-missing-format-attribute
The restrictions on @samp{offsetof} may be relaxed in a future version
of the C++ standard.
-@item -Wno-int-to-pointer-cast @r{(C and Objective-C only)}
+@item -Wno-int-to-pointer-cast
@opindex Wno-int-to-pointer-cast
@opindex Wint-to-pointer-cast
Suppress warnings from casts to pointer type of an integer of a
-different size.
+different size. In C++, casting to a pointer type of smaller size is
+an error. @option{Wint-to-pointer-cast} is enabled by default.
+
@item -Wno-pointer-to-int-cast @r{(C and Objective-C only)}
@opindex Wno-pointer-to-int-cast
-fif-conversion2 @gol
-fif-conversion @gol
-fipa-pure-const @gol
+-fipa-profile @gol
-fipa-reference @gol
-fmerge-constants
-fsplit-wide-types @gol
-findirect-inlining @gol
-fipa-sra @gol
-foptimize-sibling-calls @gol
+-fpartial-inlining @gol
-fpeephole2 @gol
-fregmove @gol
-freorder-blocks -freorder-functions @gol
-falign-labels -freorder-blocks -freorder-blocks-and-partition @gol
-fprefetch-loop-arrays -ftree-vect-loop-version}
+@item -Ofast
+@opindex Ofast
+Disregard strict standards compliance. @option{-Ofast} enables all
+@option{-O3} optimizations. It also enables optimizations that are not
+valid for all standard compliant programs.
+It turns on @option{-ffast-math}.
+
If you use multiple @option{-O} options, with or without level numbers,
the last such option is the one that is effective.
@end table
layout in order to better utilize spatial locality. This transformation is
affective for programs containing arrays of structures. Available in two
compilation modes: profile-based (enabled with @option{-fprofile-generate})
-or static (which uses built-in heuristics). Require @option{-fipa-type-escape}
-to provide the safety of this transformation. It works only in whole program
+or static (which uses built-in heuristics). It works only in whole program
mode, so it requires @option{-fwhole-program} and @option{-combine} to be
enabled. Structures considered @samp{cold} by this transformation are not
affected (see @option{--param struct-reorg-cold-struct-ratio=@var{value}}).
@item -fipa-pta
@opindex fipa-pta
-Perform interprocedural pointer analysis. This option is experimental
-and does not affect generated code.
+Perform interprocedural pointer analysis and interprocedural modification
+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.
+
+@item -fipa-profile
+@opindex fipa-profile
+Perform interprocedural profile propagation. The functions called only from
+cold functions are marked as cold. Also functions executed once (such as
+@code{cold}, @code{noreturn}, static constructors or destructors) are identified. Cold
+functions and loop less parts of functions executed once are then optimized for
+size.
+Enabled by default at @option{-O} and higher.
@item -fipa-cp
@opindex fipa-cp
Perform loop strip mining transformations on loops. Strip mining
splits a loop into two nested loops. The outer loop has strides
equal to the strip size and the inner loop has strides of the
-original loop within a strip. For example, given a loop like:
+original loop within a strip. The strip length can be changed
+using the @option{loop-block-tile-size} parameter. For example,
+given a loop like:
@smallexample
DO I = 1, N
A(I) = A(I) + C
@end smallexample
loop strip mining will transform the loop as if the user had written:
@smallexample
-DO II = 1, N, 4
- DO I = II, min (II + 3, N)
+DO II = 1, N, 51
+ DO I = II, min (II + 50, N)
A(I) = A(I) + C
ENDDO
ENDDO
@item -floop-block
Perform loop blocking transformations on loops. Blocking strip mines
each loop in the loop nest such that the memory accesses of the
-element loops fit inside caches. For example, given a loop like:
+element loops fit inside caches. The strip length can be changed
+using the @option{loop-block-tile-size} parameter. For example, given
+a loop like:
@smallexample
DO I = 1, N
DO J = 1, M
@end smallexample
loop blocking will transform the loop as if the user had written:
@smallexample
-DO II = 1, N, 64
- DO JJ = 1, M, 64
- DO I = II, min (II + 63, N)
- DO J = JJ, min (JJ + 63, M)
+DO II = 1, N, 51
+ DO JJ = 1, M, 51
+ DO I = II, min (II + 50, N)
+ DO J = JJ, min (JJ + 50, M)
A(J, I) = B(I) + C(J)
ENDDO
ENDDO
Compare the results of several data dependence analyzers. This option
is used for debugging the data dependence analyzers.
+@item -ftree-loop-if-convert
+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
+vectorization pass to handle these loops. This is enabled by default
+if vectorization is enabled.
+
@item -ftree-loop-distribution
Perform loop distribution. This flag can improve cache performance on
big loop bodies and allow further loop optimizations, like
ENDDO
@end smallexample
+@item -ftree-loop-distribute-patterns
+Perform loop distribution of patterns that can be code generated with
+calls to a library. This flag is enabled by default at @option{-O3}.
+
+This pass distributes the initialization loops and generates a call to
+memset zero. For example, the loop
+@smallexample
+DO I = 1, N
+ A(I) = 0
+ B(I) = A(I) + I
+ENDDO
+@end smallexample
+is transformed to
+@smallexample
+DO I = 1, N
+ A(I) = 0
+ENDDO
+DO I = 1, N
+ B(I) = A(I) + I
+ENDDO
+@end smallexample
+and the initialization loop is transformed into a call to memset zero.
+
@item -ftree-loop-im
@opindex ftree-loop-im
Perform loop invariant motion on trees. This pass moves only invariants that
With this option, the compiler will create multiple copies of some
local variables when unrolling a loop which can result in superior code.
+@item -fpartial-inlining
+@opindex fpartial-inlining
+Inline parts of functions. This option has any effect only
+when inlining itself is turned on by the @option{-finline-functions}
+or @option{-finline-small-functions} options.
+
+Enabled at level @option{-O2}.
+
@item -fpredictive-commoning
@opindex fpredictive-commoning
Perform predictive commoning optimization, i.e., reusing computations
Assume that the current compilation unit represents the whole program being
compiled. All public functions and variables with the exception of @code{main}
and those merged by attribute @code{externally_visible} become static functions
-and in effect are optimized more aggressively by interprocedural optimizers.
+and in effect are optimized more aggressively by interprocedural optimizers. If @command{gold} is used as the linker plugin, @code{externally_visible} attributes are automatically added to functions (not variable yet due to a current @command{gold} issue) that are accessed outside of LTO objects according to resolution file produced by @command{gold}. For other linkers that cannot generate resolution file, explicit @code{externally_visible} attributes are still necessary.
While this option is equivalent to proper use of the @code{static} keyword for
programs consisting of a single file, in combination with option
@option{-combine}, @option{-flto} or @option{-fwhopr} this flag can be used to
was mixing languages before, all you need to add is @option{-flto} to
all the compile and link commands.
+If LTO encounters objects with C linkage declared with incompatible
+types in separate translation units to be linked together (undefined
+behavior according to ISO C99 6.2.7), a non-fatal diagnostic may be
+issued. The behavior is still undefined at runtime.
+
If object files containing GIMPLE bytecode are stored in a library
archive, say @file{libfoo.a}, it is possible to extract and use them
in an LTO link if you are using @command{gold} as the linker (which,
This option is disabled by default.
-@item -fwhopr
+@item -fwhopr[=@var{n}]
@opindex fwhopr
This option is identical in functionality to @option{-flto} but it
differs in how the final link stage is executed. Instead of loading
that otherwise would not fit in memory. This option enables
@option{-fwpa} and @option{-fltrans} automatically.
-Disabled by default.
+If you specify the optional @var{n} the link stage is executed in
+parallel using @var{n} parallel jobs by utilizing an installed
+@command{make} program. The environment variable @env{MAKE} may be
+used to override the program used.
-This option is experimental.
+Disabled by default.
@item -fwpa
@opindex fwpa
by the compiler will be investigated. To those functions, a different
(more restrictive) limit compared to functions declared inline can
be applied.
-The default value is 50.
+The default value is 40.
@item large-function-insns
The limit specifying really large functions. For functions larger than this
vectorization needs to be greater than the value specified by this option
to allow vectorization. The default value is 0.
+@item gcse-cost-distance-ratio
+Scaling factor in calculation of maximum distance an expression
+can be moved by GCSE optimizations. This is currently supported only in
+code hoisting pass. The bigger the ratio, the more agressive code hoisting
+will be with simple expressions, i.e., the expressions which have cost
+less than @option{gcse-unrestricted-cost}. Specifying 0 will disable
+hoisting of simple expressions. The default value is 10.
+
+@item gcse-unrestricted-cost
+Cost, roughly measured as the cost of a single typical machine
+instruction, at which GCSE optimizations will not constrain
+the distance an expression can travel. This is currently
+supported only in code hoisting pass. The lesser the cost,
+the more aggressive code hoisting will be. Specifying 0 will
+allow all expressions to travel unrestricted distances.
+The default value is 3.
+
+@item max-hoist-depth
+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 will avoid limiting the search, but may slow down compilation
+of huge functions. The default value is 30.
+
@item max-unrolled-insns
The maximum number of instructions that a loop should have if that loop
is unrolled, and if the loop is unrolled, it determines how many times
@item min-insn-to-prefetch-ratio
The minimum ratio between the number of instructions and the
-number of prefetches to enable prefetching in a loop with an
-unknown trip count.
+number of prefetches to enable prefetching in a loop.
@item prefetch-min-insn-to-mem-ratio
The minimum ratio between the number of instructions and the
@option{ipa-sra-ptr-growth-factor} times the size of the original
pointer parameter.
+@item graphite-max-nb-scop-params
+To avoid exponential effects in the Graphite loop transforms, the
+number of parameters in a Static Control Part (SCoP) is bounded. The
+default value is 10 parameters. A variable whose value is unknown at
+compile time and defined outside a SCoP is a parameter of the SCoP.
+
+@item graphite-max-bbs-per-function
+To avoid exponential effects in the detection of SCoPs, the size of
+the functions analyzed by Graphite is bounded. The default value is
+100 basic blocks.
+
+@item loop-block-tile-size
+Loop blocking or strip mining transforms, enabled with
+@option{-floop-block} or @option{-floop-strip-mine}, strip mine each
+loop in the loop nest by a given number of iterations. The strip
+length can be changed using the @option{loop-block-tile-size}
+parameter. The default value is 51 iterations.
+
+@item devirt-type-list-size
+IPA-CP attempts to track all possible types passed to a function's
+parameter in order to perform devirtualization.
+@option{devirt-type-list-size} is the maximum number of types it
+stores per a single formal parameter of a function.
+
@end table
@end table
If you really need to change the search order for system directories,
use the @option{-nostdinc} and/or @option{-isystem} options.
+@item -iplugindir=@var{dir}
+Set the directory to search for plugins which are passed
+by @option{-fplugin=@var{name}} instead of
+@option{-fplugin=@var{path}/@var{name}.so}. This option is not meant
+to be used by the user, but only passed by the driver.
+
@item -iquote@var{dir}
@opindex iquote
Add the directory @var{dir} to the head of the list of directories to
The usual way to run GCC is to run the executable called @file{gcc}, or
@file{<machine>-gcc} when cross-compiling, or
@file{<machine>-gcc-<version>} to run a version other than the one that
-was installed last. Sometimes this is inconvenient, so GCC provides
-options that will switch to another cross-compiler or version.
-
-@table @gcctabopt
-@item -b @var{machine}
-@opindex b
-The argument @var{machine} specifies the target machine for compilation.
-
-The value to use for @var{machine} is the same as was specified as the
-machine type when configuring GCC as a cross-compiler. For
-example, if a cross-compiler was configured with @samp{configure
-arm-elf}, meaning to compile for an arm processor with elf binaries,
-then you would specify @option{-b arm-elf} to run that cross compiler.
-Because there are other options beginning with @option{-b}, the
-configuration must contain a hyphen, or @option{-b} alone should be one
-argument followed by the configuration in the next argument.
-
-@item -V @var{version}
-@opindex V
-The argument @var{version} specifies which version of GCC to run.
-This is useful when multiple versions are installed. For example,
-@var{version} might be @samp{4.0}, meaning to run GCC version 4.0.
-@end table
-
-The @option{-V} and @option{-b} options work by running the
-@file{<machine>-gcc-<version>} executable, so there's no real reason to
-use them if you can just run that directly.
+was installed last.
@node Submodel Options
@section Hardware Models and Configurations
@cindex hardware models and configurations, specifying
@cindex machine dependent options
-Earlier we discussed the standard option @option{-b} which chooses among
-different installed compilers for completely different target
-machines, such as VAX vs.@: 68000 vs.@: 80386.
-
-In addition, each of these target machine types can have its own
+Each target machine types can have its own
special options, starting with @samp{-m}, to choose among various
hardware models or configurations---for example, 68010 vs 68020,
floating coprocessor or none. A single installed version of the
by default. This can be overridden with the @code{section} attribute.
@xref{Variable Attributes}.
-@item -mfix-cortex-m3-ldrd
-@opindex mfix-cortex-m3-ldrd
-Some Cortex-M3 cores can cause data corruption when @code{ldrd} instructions
-with overlapping destination and base registers are used. This option avoids
-generating these instructions. This option is enabled by default when
-@option{-mcpu=cortex-m3} is specified.
-
@end table
@node ARM Options
@samp{arm1136j-s}, @samp{arm1136jf-s}, @samp{mpcore}, @samp{mpcorenovfp},
@samp{arm1156t2-s}, @samp{arm1156t2f-s}, @samp{arm1176jz-s}, @samp{arm1176jzf-s},
@samp{cortex-a5}, @samp{cortex-a8}, @samp{cortex-a9},
-@samp{cortex-r4}, @samp{cortex-r4f}, @samp{cortex-m3},
+@samp{cortex-r4}, @samp{cortex-r4f}, @samp{cortex-m4}, @samp{cortex-m3},
@samp{cortex-m1},
@samp{cortex-m0},
@samp{xscale}, @samp{iwmmxt}, @samp{iwmmxt2}, @samp{ep9312}.
If @option{-msoft-float} is specified this specifies the format of
floating point values.
+If the selected floating-point hardware includes the NEON extension
+(e.g. @option{-mfpu}=@samp{neon}), note that floating-point
+operations will not be used by GCC's auto-vectorization pass unless
+@option{-funsafe-math-optimizations} is also specified. This is
+because NEON hardware does not fully implement the IEEE 754 standard for
+floating-point arithmetic (in particular denormal values are treated as
+zero), so the use of NEON instructions may lead to a loss of precision.
+
@item -mfp16-format=@var{name}
@opindex mfp16-format
Specify the format of the @code{__fp16} half-precision floating-point type.
loader imposes this restriction, and when @option{-fpic} or @option{-fPIC}
is specified.
+@item -mfix-cortex-m3-ldrd
+@opindex mfix-cortex-m3-ldrd
+Some Cortex-M3 cores can cause data corruption when @code{ldrd} instructions
+with overlapping destination and base registers are used. This option avoids
+generating these instructions. This option is enabled by default when
+@option{-mcpu=cortex-m3} is specified.
+
@end table
@node AVR Options
@table @gcctabopt
@item -mglibc
@opindex mglibc
-Use the GNU C library instead of uClibc. This is the default except
-on @samp{*-*-linux-*uclibc*} targets.
+Use the GNU C library. This is the default except
+on @samp{*-*-linux-*uclibc*} and @samp{*-*-linux-*android*} targets.
@item -muclibc
@opindex muclibc
-Use uClibc instead of the GNU C library. This is the default on
+Use uClibc C library. This is the default on
@samp{*-*-linux-*uclibc*} targets.
+
+@item -mbionic
+@opindex mbionic
+Use Bionic C library. This is the default on
+@samp{*-*-linux-*android*} targets.
+
+@item -mandroid
+@opindex mandroid
+Compile code compatible with Android platform. This is the default on
+@samp{*-*-linux-*android*} targets.
+
+When compiling, this option enables @option{-mbionic}, @option{-fPIC},
+@option{-fno-exceptions} and @option{-fno-rtti} by default. When linking,
+this option makes the GCC driver pass Android-specific options to the linker.
+Finally, this option causes the preprocessor macro @code{__ANDROID__}
+to be defined.
+
+@item -tno-android-cc
+@opindex tno-android-cc
+Disable compilation effects of @option{-mandroid}, i.e., do not enable
+@option{-mbionic}, @option{-fPIC}, @option{-fno-exceptions} and
+@option{-fno-rtti} by default.
+
+@item -tno-android-ld
+@opindex tno-android-ld
+Disable linking effects of @option{-mandroid}, i.e., pass standard Linux
+linking options to the linker.
+
@end table
@node H8/300 Options
@itemx -mno-aes
@itemx -mpclmul
@itemx -mno-pclmul
+@itemx -mfsgsbase
+@itemx -mno-fsgsbase
+@itemx -mrdrnd
+@itemx -mno-rdrnd
+@itemx -mf16c
+@itemx -mno-f16c
@itemx -msse4a
@itemx -mno-sse4a
@itemx -mfma4
@opindex m3dnow
@opindex mno-3dnow
These switches enable or disable the use of instructions in the MMX,
-SSE, SSE2, SSE3, SSSE3, SSE4.1, AVX, AES, PCLMUL, SSE4A, FMA4, XOP,
-LWP, ABM or 3DNow!@: extended instruction sets.
+SSE, SSE2, SSE3, SSSE3, SSE4.1, AVX, AES, PCLMUL, FSGSBASE, RDRND,
+F16C, SSE4A, FMA4, XOP, LWP, ABM or 3DNow!@: extended instruction sets.
These extensions are also available as built-in functions: see
@ref{X86 Built-in Functions}, for details of the functions enabled and
disabled by these switches.
@opindex msse2avx
Specify that the assembler should encode SSE instructions with VEX
prefix. The option @option{-mavx} turns this on by default.
+
+@item -mfentry
+@itemx -mno-fentry
+@opindex mfentry
+If profiling is active @option{-pg} put the profiling
+counter call before prologue.
+Note: On x86 architectures the attribute @code{ms_hook_prologue}
+isn't possible at the moment for @option{-mfentry} and @option{-pg}.
@end table
These @samp{-m} switches are supported in addition to the above
@samp{7400}, @samp{7450}, @samp{750}, @samp{801}, @samp{821}, @samp{823},
@samp{860}, @samp{970}, @samp{8540}, @samp{a2}, @samp{e300c2},
@samp{e300c3}, @samp{e500mc}, @samp{e500mc64}, @samp{ec603e}, @samp{G3},
-@samp{G4}, @samp{G5}, @samp{power}, @samp{power2}, @samp{power3},
+@samp{G4}, @samp{G5}, @samp{titan}, @samp{power}, @samp{power2}, @samp{power3},
@samp{power4}, @samp{power5}, @samp{power5+}, @samp{power6}, @samp{power6x},
@samp{power7}, @samp{common}, @samp{powerpc}, @samp{powerpc64}, @samp{rios},
@samp{rios1}, @samp{rios2}, @samp{rsc}, and @samp{rs64}.
architecture, registers, and mnemonics set by @option{-mcpu}, but the
scheduling parameters set by @option{-mtune}.
-@item -mswdiv
-@itemx -mno-swdiv
-@opindex mswdiv
-@opindex mno-swdiv
-Generate code to compute division as reciprocal estimate and iterative
-refinement, creating opportunities for increased throughput. This
-feature requires: optional PowerPC Graphics instruction set for single
-precision and FRE instruction for double precision, assuming divides
-cannot generate user-visible traps, and the domain values not include
-Infinities, denormals or zero denominator.
+@item -mcmodel=small
+@opindex mcmodel=small
+Generate PowerPC64 code for the small model: The TOC is limited to
+64k.
+
+@item -mcmodel=large
+@opindex mcmodel=large
+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 address
+space.
@item -maltivec
@itemx -mno-altivec
@itemx -mno-relocatable
@opindex mrelocatable
@opindex mno-relocatable
-On embedded PowerPC systems generate code that allows (does not allow)
-the program to be relocated to a different address at runtime. If you
-use @option{-mrelocatable} on any module, all objects linked together must
-be compiled with @option{-mrelocatable} or @option{-mrelocatable-lib}.
+Generate code that allows (does not allow) a static executable to be
+relocated to a different address at runtime. A simple embedded
+PowerPC system loader should relocate the entire contents of
+@code{.got2} and 4-byte locations listed in the @code{.fixup} section,
+a table of 32-bit addresses generated by this option. For this to
+work, all objects linked together must be compiled with
+@option{-mrelocatable} or @option{-mrelocatable-lib}.
+@option{-mrelocatable} code aligns the stack to an 8 byte boundary.
@item -mrelocatable-lib
@itemx -mno-relocatable-lib
@opindex mrelocatable-lib
@opindex mno-relocatable-lib
-On embedded PowerPC systems generate code that allows (does not allow)
-the program to be relocated to a different address at runtime. Modules
-compiled with @option{-mrelocatable-lib} can be linked with either modules
-compiled without @option{-mrelocatable} and @option{-mrelocatable-lib} or
-with modules compiled with the @option{-mrelocatable} options.
+Like @option{-mrelocatable}, @option{-mrelocatable-lib} generates a
+@code{.fixup} section to allow static executables to be relocated at
+runtime, but @option{-mrelocatable-lib} does not use the smaller stack
+alignment of @option{-mrelocatable}. Objects compiled with
+@option{-mrelocatable-lib} may be linked with objects compiled with
+any combination of the @option{-mrelocatable} options.
@item -mno-toc
@itemx -mtoc
in the @samp{.data} section, and all uninitialized data in the
@samp{.bss} section.
+@item -mblock-move-inline-limit=@var{num}
+@opindex mblock-move-inline-limit
+Inline all block moves (such as calls to @code{memcpy} or structure
+copies) less than or equal to @var{num} bytes. The minimum value for
+@var{num} is 32 bytes on 32-bit targets and 64 bytes on 64-bit
+targets. The default value is target-specific.
+
@item -G @var{num}
@opindex G
@cindex smaller data references (PowerPC)
Adds support for multithreading with the @dfn{pthreads} library.
This option sets flags for both the preprocessor and linker.
+@item -mrecip
+@itemx -mno-recip
+@opindex mrecip
+This option will enable GCC to use 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 @option{-ffast-math} option when using @option{-mrecip} (or at
+least @option{-funsafe-math-optimizations},
+@option{-finite-math-only}, @option{-freciprocal-math} and
+@option{-fno-trapping-math}). Note that while the throughput of the
+sequence is generally 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) for reciprocal square
+roots.
+
+@item -mrecip=@var{opt}
+@opindex mrecip=opt
+This option allows to control which reciprocal estimate instructions
+may be used. @var{opt} is a comma separated list of options, that may
+be preceeded by a @code{!} to invert the option:
+@code{all}: enable all estimate instructions,
+@code{default}: enable the default instructions, equvalent to @option{-mrecip},
+@code{none}: disable all estimate instructions, equivalent to @option{-mno-recip};
+@code{div}: enable the reciprocal approximation instructions for both single and double precision;
+@code{divf}: enable the single precision reciprocal approximation instructions;
+@code{divd}: enable the double precision reciprocal approximation instructions;
+@code{rsqrt}: enable the reciprocal square root approximation instructions for both single and double precision;
+@code{rsqrtf}: enable the single precision reciprocal square root approximation instructions;
+@code{rsqrtd}: enable the double precision reciprocal square root approximation instructions;
+
+So for example, @option{-mrecip=all,!rsqrtd} would enable the
+all of the reciprocal estimate instructions, except for the
+@code{FRSQRTE}, @code{XSRSQRTEDP}, and @code{XVRSQRTEDP} instructions
+which handle the double precision reciprocal square root calculations.
+
+@item -mrecip-precision
+@itemx -mno-recip-precision
+@opindex mrecip-precision
+Assume (do not assume) that the reciprocal estimate instructions
+provide higher precision estimates than is mandated by the powerpc
+ABI. Selecting @option{-mcpu=power6} or @option{-mcpu=power7}
+automatically selects @option{-mrecip-precision}. 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 after three steps.
@end table
@node RX Options
This is because the RX FPU instructions are themselves unsafe.
@item -mcpu=@var{name}
-@itemx -patch=@var{name}
@opindex -mcpu
-@opindex -patch
Selects the type of RX CPU to be targeted. Currently three types are
supported, the generic @var{RX600} and @var{RX200} series hardware and
the specific @var{RX610} cpu. The default is @var{RX600}.
slows down the case of larger dividends. inv20u assumes the case of a such
a small dividend to be unlikely, and inv20l assumes it to be likely.
+@item -maccumulate-outgoing-args
+@opindex maccumulate-outgoing-args
+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.
+
@item -mdivsi3_libfunc=@var{name}
@opindex mdivsi3_libfunc=@var{name}
Set the name of the library function used for 32 bit signed division to
@opindex mno-app-regs
This option will cause r2 and r5 to be treated as fixed registers.
+@item -mv850e2v3
+@opindex mv850e2v3
+Specify that the target processor is the V850E2V3. The preprocessor
+constants @samp{__v850e2v3__} will be defined if
+this option is used.
+
+@item -mv850e2
+@opindex mv850e2
+Specify that the target processor is the V850E2. The preprocessor
+constants @samp{__v850e2__} will be defined if
+
@item -mv850e1
@opindex mv850e1
Specify that the target processor is the V850E1. The preprocessor
constants @samp{__v850e1__} and @samp{__v850e__} will be defined if
-this option is used.
@item -mv850e
@opindex mv850e
constant @samp{__v850e__} will be defined if this option is used.
If neither @option{-mv850} nor @option{-mv850e} nor @option{-mv850e1}
+nor @option{-mv850e2} nor @option{-mv850e2v3}
are defined then a default target processor will be chosen and the
relevant @samp{__v850*__} preprocessor constant will be defined.
@item -mdisable-callt
@opindex mdisable-callt
This option will suppress generation of the CALLT instruction for the
-v850e and v850e1 flavors of the v850 architecture. The default is
+v850e, v850e1, v850e2 and v850e2v3 flavors of the v850 architecture. The default is
@option{-mno-disable-callt} which allows the CALLT instruction to be used.
@end table
The default is @option{-mserialize-volatile}. Use
@option{-mno-serialize-volatile} to omit the @code{MEMW} instructions.
+@item -mforce-no-pic
+@opindex mforce-no-pic
+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.
+
@item -mtext-section-literals
@itemx -mno-text-section-literals
@opindex mtext-section-literals
@option{-Wl,--defsym,__stack_limit=0x7ffe0000} to enforce a stack limit
of 128KB@. Note that this may only work with the GNU linker.
-@cindex aliasing of parameters
-@cindex parameters, aliased
-@item -fargument-alias
-@itemx -fargument-noalias
-@itemx -fargument-noalias-global
-@itemx -fargument-noalias-anything
-@opindex fargument-alias
-@opindex fargument-noalias
-@opindex fargument-noalias-global
-@opindex fargument-noalias-anything
-Specify the possible relationships among parameters and between
-parameters and global data.
-
-@option{-fargument-alias} specifies that arguments (parameters) may
-alias each other and may alias global storage.@*
-@option{-fargument-noalias} specifies that arguments do not alias
-each other, but may alias global storage.@*
-@option{-fargument-noalias-global} specifies that arguments do not
-alias each other and do not alias global storage.
-@option{-fargument-noalias-anything} specifies that arguments do not
-alias any other storage.
-
-Each language will automatically use whatever option is required by
-the language standard. You should not need to use these options yourself.
-
@item -fleading-underscore
@opindex fleading-underscore
This option and its counterpart, @option{-fno-leading-underscore}, forcibly
An overview of these techniques, their benefits and how to use them
is at @w{@uref{http://gcc.gnu.org/wiki/Visibility}}.
+@item -fstrict-volatile-bitfields
+This option should be used if accesses to volatile bitfields (or other
+structure fields, although the compiler usually honors those types
+anyway) should use a single access in a mode of the same size as the
+container's type, aligned to a natural alignment if possible. For
+example, targets with memory-mapped peripheral registers might require
+all such accesses to be 16 bits wide; with this flag the user could
+declare all peripheral bitfields as ``unsigned short'' (assuming short
+is 16 bits on these targets) to force GCC to use 16 bit accesses
+instead of, perhaps, a more efficient 32 bit access.
+
+If this option is disabled, the compiler will use the most efficient
+instruction. In the previous example, that might be a 32-bit load
+instruction, even though that will access bytes that do not contain
+any portion of the bitfield, or memory-mapped registers unrelated to
+the one being updated.
+
+If the target requires strict alignment, and honoring the container
+type would require violating this alignment, a warning is issued.
+However, the access happens as the user requested, under the
+assumption that the user knows something about the target hardware
+that GCC is unaware of.
+
+The default value of this option is determined by the application binary
+interface for the target processor.
+
@end table
@c man end
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