-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} @gol
--fdump-ada-spec@r{[}-slim@r{]}} -fdump-go-spec=@var{file}
+-fdump-ada-spec@r{[}-slim@r{]} -fdump-go-spec=@var{file}}
@item C Language Options
@xref{C Dialect Options,,Options Controlling C Dialect}.
@item C++ Language Options
@xref{C++ Dialect Options,,Options Controlling C++ Dialect}.
@gccoptlist{-fabi-version=@var{n} -fno-access-control -fcheck-new @gol
--fconserve-space -ffriend-injection @gol
+-fconserve-space -fconstexpr-depth=@var{n} -ffriend-injection @gol
-fno-elide-constructors @gol
-fno-enforce-eh-specs @gol
-ffor-scope -fno-for-scope -fno-gnu-keywords @gol
@gccoptlist{-fconstant-string-class=@var{class-name} @gol
-fgnu-runtime -fnext-runtime @gol
-fno-nil-receivers @gol
+-fobjc-abi-version=@var{n} @gol
-fobjc-call-cxx-cdtors @gol
-fobjc-direct-dispatch @gol
-fobjc-exceptions @gol
-fobjc-gc @gol
+-fobjc-nilcheck @gol
-fobjc-std=objc1 @gol
-freplace-objc-classes @gol
-fzero-link @gol
@xref{Language Independent Options,,Options to Control Diagnostic Messages Formatting}.
@gccoptlist{-fmessage-length=@var{n} @gol
-fdiagnostics-show-location=@r{[}once@r{|}every-line@r{]} @gol
--fdiagnostics-show-option}
+-fno-diagnostics-show-option}
@item Warning Options
@xref{Warning Options,,Options to Request or Suppress Warnings}.
-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 -Wcpp -Wno-deprecated @gol
+-Wconversion -Wcoverage-mismatch -Wno-cpp -Wno-deprecated @gol
-Wno-deprecated-declarations -Wdisabled-optimization @gol
-Wno-div-by-zero -Wdouble-promotion -Wempty-body -Wenum-compare @gol
-Wno-endif-labels -Werror -Werror=* @gol
-Wformat-security -Wformat-y2k @gol
-Wframe-larger-than=@var{len} -Wjump-misses-init -Wignored-qualifiers @gol
-Wimplicit -Wimplicit-function-declaration -Wimplicit-int @gol
--Winit-self -Winline @gol
+-Winit-self -Winline -Wmaybe-uninitialized @gol
-Wno-int-to-pointer-cast -Wno-invalid-offsetof @gol
-Winvalid-pch -Wlarger-than=@var{len} -Wunsafe-loop-optimizations @gol
-Wlogical-op -Wlong-long @gol
--Wmain -Wmissing-braces -Wmissing-field-initializers @gol
+-Wmain -Wmaybe-uninitialized -Wmissing-braces -Wmissing-field-initializers @gol
-Wmissing-format-attribute -Wmissing-include-dirs @gol
-Wno-mudflap @gol
-Wno-multichar -Wnonnull -Wno-overflow @gol
-fcompare-debug@r{[}=@var{opts}@r{]} -fcompare-debug-second @gol
-feliminate-dwarf2-dups -feliminate-unused-debug-types @gol
-feliminate-unused-debug-symbols -femit-class-debug-always @gol
--fenable-icf-debug @gol
+-fdebug-types-section @gol
-fmem-report -fpre-ipa-mem-report -fpost-ipa-mem-report -fprofile-arcs @gol
-frandom-seed=@var{string} -fsched-verbose=@var{n} @gol
-fsel-sched-verbose -fsel-sched-dump-cfg -fsel-sched-pipelining-verbose @gol
-finline-functions -finline-functions-called-once -finline-limit=@var{n} @gol
-finline-small-functions -fipa-cp -fipa-cp-clone -fipa-matrix-reorg @gol
-fipa-pta -fipa-profile -fipa-pure-const -fipa-reference @gol
--fipa-struct-reorg -fira-algorithm=@var{algorithm} @gol
+-fira-algorithm=@var{algorithm} @gol
-fira-region=@var{region} @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-flatten -floop-interchange -floop-strip-mine @gol
--floop-parallelize-all -flto -flto-compression-level
+-floop-parallelize-all -flto -flto-compression-level @gol
-flto-partition=@var{alg} -flto-report -fmerge-all-constants @gol
-fmerge-constants -fmodulo-sched -fmodulo-sched-allow-regmoves @gol
-fmove-loop-invariants fmudflap -fmudflapir -fmudflapth -fno-branch-count-reg @gol
-ftree-builtin-call-dce -ftree-ccp -ftree-ch -ftree-copy-prop @gol
-ftree-copyrename -ftree-dce -ftree-dominator-opts -ftree-dse @gol
-ftree-forwprop -ftree-fre -ftree-loop-if-convert @gol
--ftree-loop-if-convert-memory-writes -ftree-loop-im @gol
+-ftree-loop-if-convert-stores -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
@item Directory Options
@xref{Directory Options,,Options for Directory Search}.
-@gccoptlist{-B@var{prefix} -I@var{dir} -iplugindir=@var{dir}}
--iquote@var{dir} -L@var{dir} -specs=@var{file} -I-
---sysroot=@var{dir}
+@gccoptlist{-B@var{prefix} -I@var{dir} -iplugindir=@var{dir} @gol
+-iquote@var{dir} -L@var{dir} -specs=@var{file} -I- @gol
+--sysroot=@var{dir}}
@item Machine Dependent Options
@xref{Submodel Options,,Hardware Models and Configurations}.
@c Try and put the significant identifier (CPU or system) first,
@c so users have a clue at guessing where the ones they want will be.
-@emph{ARC Options}
-@gccoptlist{-EB -EL @gol
--mmangle-cpu -mcpu=@var{cpu} -mtext=@var{text-section} @gol
--mdata=@var{data-section} -mrodata=@var{readonly-data-section}}
-
@emph{ARM Options}
@gccoptlist{-mapcs-frame -mno-apcs-frame @gol
-mabi=@var{name} @gol
-mapcs-reentrant -mno-apcs-reentrant @gol
-msched-prolog -mno-sched-prolog @gol
-mlittle-endian -mbig-endian -mwords-little-endian @gol
--mfloat-abi=@var{name} -msoft-float -mhard-float -mfpe @gol
+-mfloat-abi=@var{name} -mfpe @gol
-mfp16-format=@var{name}
-mthumb-interwork -mno-thumb-interwork @gol
-mcpu=@var{name} -march=@var{name} -mfpu=@var{name} @gol
-melf -maout -melinux -mlinux -sim -sim2 @gol
-mmul-bug-workaround -mno-mul-bug-workaround}
-@emph{CRX Options}
-@gccoptlist{-mmac -mpush-args}
-
@emph{Darwin Options}
@gccoptlist{-all_load -allowable_client -arch -arch_errors_fatal @gol
-arch_only -bind_at_load -bundle -bundle_loader @gol
-masm=@var{dialect} -mno-fancy-math-387 @gol
-mno-fp-ret-in-387 -msoft-float @gol
-mno-wide-multiply -mrtd -malign-double @gol
--mpreferred-stack-boundary=@var{num}
+-mpreferred-stack-boundary=@var{num} @gol
-mincoming-stack-boundary=@var{num} @gol
-mcld -mcx16 -msahf -mmovbe -mcrc32 -mrecip -mvzeroupper @gol
-mmmx -msse -msse2 -msse3 -mssse3 -msse4.1 -msse4.2 -msse4 -mavx @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 -mfentry -m8bit-idiv}
+-msse2avx -mfentry -m8bit-idiv @gol
+-mavx256-split-unaligned-load -mavx256-split-unaligned-store}
+
+@emph{i386 and x86-64 Windows Options}
+@gccoptlist{-mconsole -mcygwin -mno-cygwin -mdll @gol
+-mnop-fun-dllimport -mthread @gol
+-municode -mwin32 -mwindows -fno-set-stack-executable}
@emph{IA-64 Options}
@gccoptlist{-mbig-endian -mlittle-endian -mgnu-as -mgnu-ld -mno-pic @gol
-mshared-library-id=n -mid-shared-library -mno-id-shared-library @gol
-mxgot -mno-xgot}
-@emph{M68hc1x Options}
-@gccoptlist{-m6811 -m6812 -m68hc11 -m68hc12 -m68hcs12 @gol
--mauto-incdec -minmax -mlong-calls -mshort @gol
--msoft-reg-count=@var{count}}
-
@emph{MCore Options}
@gccoptlist{-mhardlit -mno-hardlit -mdiv -mno-div -mrelax-immediates @gol
-mno-relax-immediates -mwide-bitfields -mno-wide-bitfields @gol
-mdivide-traps -mdivide-breaks @gol
-mmemcpy -mno-memcpy -mlong-calls -mno-long-calls @gol
-mmad -mno-mad -mfused-madd -mno-fused-madd -nocpp @gol
+-mfix-24k -mno-fix-24k @gol
-mfix-r4000 -mno-fix-r4000 -mfix-r4400 -mno-fix-r4400 @gol
-mfix-r10000 -mno-fix-r10000 -mfix-vr4120 -mno-fix-vr4120 @gol
-mfix-vr4130 -mno-fix-vr4130 -mfix-sb1 -mno-fix-sb1 @gol
-mno-am33 -mam33 -mam33-2 -mam34 @gol
-mtune=@var{cpu-type} @gol
-mreturn-pointer-on-d0 @gol
--mno-crt0 -mrelax -mliw}
+-mno-crt0 -mrelax -mliw -msetlb}
@emph{PDP-11 Options}
@gccoptlist{-mfpu -msoft-float -mac0 -mno-ac0 -m40 -m45 -m10 @gol
-mprototype -mno-prototype @gol
-msim -mmvme -mads -myellowknife -memb -msdata @gol
-msdata=@var{opt} -mvxworks -G @var{num} -pthread @gol
--mrecip -mrecip=@var{opt} -mno-recip -mrecip-precision
+-mrecip -mrecip=@var{opt} -mno-recip -mrecip-precision @gol
-mno-recip-precision @gol
-mveclibabi=@var{type} -mfriz -mno-friz}
@emph{Solaris 2 Options}
@gccoptlist{-mimpure-text -mno-impure-text @gol
--threads -pthreads -pthread}
+-pthreads -pthread}
@emph{SPARC Options}
@gccoptlist{-mcpu=@var{cpu-type} @gol
@emph{x86-64 Options}
See i386 and x86-64 Options.
-@emph{i386 and x86-64 Windows Options}
-@gccoptlist{-mconsole -mcygwin -mno-cygwin -mdll
--mnop-fun-dllimport -mthread @gol
--municode -mwin32 -mwindows -fno-set-stack-executable}
-
@emph{Xstormy16 Options}
@gccoptlist{-msim}
Version 4 implements a standard mangling for vector types.
+Version 5 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.
+
See also @option{-Wabi}.
@item -fno-access-control
This option is no longer useful on most targets, now that support has
been added for putting variables into BSS without making them common.
+@item -fconstexpr-depth=@var{n}
+@opindex fconstexpr-depth
+Set the maximum nested evaluation depth for C++0x constexpr functions
+to @var{n}. A limit is needed to detect endless recursion during
+constant expression evaluation. The minimum specified by the standard
+is 512.
+
@item -fno-deduce-init-list
@opindex fno-deduce-init-list
Disable deduction of a template type parameter as
@cindex Objective-C and Objective-C++ options, command line
@cindex options, Objective-C and Objective-C++
(NOTE: This manual does not describe the Objective-C and Objective-C++
-languages themselves. See @xref{Standards,,Language Standards
+languages themselves. @xref{Standards,,Language Standards
Supported by GCC}, for references.)
This section describes the command-line options that are only meaningful
Assume that all Objective-C message dispatches (@code{[receiver
message:arg]}) in this translation unit ensure that the receiver is
not @code{nil}. This allows for more efficient entry points in the
-runtime to be used. Currently, this option is only available in
-conjunction with the NeXT runtime on Mac OS X 10.3 and later.
+runtime to be used. This option is only available in conjunction with
+the NeXT runtime and ABI version 0 or 1.
+
+@item -fobjc-abi-version=@var{n}
+@opindex fobjc-abi-version
+Use version @var{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 support 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.
@item -fobjc-call-cxx-cdtors
@opindex fobjc-call-cxx-cdtors
GNU runtime has a different garbage collection implementation that
does not require special compiler flags.
+@item -fobjc-nilcheck
+@opindex fobjc-nilcheck
+For the NeXT runtime with version 2 of the ABI, check for a nil
+receiver in method invocations before doing the actual method call.
+This is the default and can be disabled using
+@option{-fno-objc-nilcheck}. 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 nothing when the GNU runtime, or an older
+version of the NeXT runtime ABI, is used.
+
@item -fobjc-std=objc1
@opindex fobjc-std
Conform to the language syntax of Objective-C 1.0, the language
prefix) for physical lines that result from the process of breaking
a message which is too long to fit on a single line.
-@item -fdiagnostics-show-option
+@item -fno-diagnostics-show-option
+@opindex fno-diagnostics-show-option
@opindex fdiagnostics-show-option
-This option instructs the diagnostic machinery to add text to each
-diagnostic emitted, which indicates which command line option directly
-controls that diagnostic, when such an option is known to the
-diagnostic machinery.
+By default, each diagnostic emitted includes text which indicates the
+command line option that directly controls the diagnostic (if such an
+option is known to the diagnostic machinery). Specifying the
+@option{-fno-diagnostics-show-option} flag suppresses that behavior.
@item -Wcoverage-mismatch
@opindex Wcoverage-mismatch
negative form, to be used to negate @option{-Werror} for specific
warnings, for example @option{-Wno-error=switch} makes
@option{-Wswitch} warnings not be errors, even when @option{-Werror}
-is in effect. You can use the @option{-fdiagnostics-show-option}
-option to have each controllable warning amended with the option which
-controls it, to determine what to use with this option.
+is in effect.
+
+The warning message for each controllable warning includes the
+option which controls the warning. That option can then be used with
+@option{-Werror=} and @option{-Wno-error=} as described above.
+(Printing of the option in the warning message can be disabled using the
+@option{-fno-diagnostics-show-option} flag.)
Note that specifying @option{-Werror=}@var{foo} automatically implies
@option{-W}@var{foo}. However, @option{-Wno-error=}@var{foo} does not
-Wcomment @gol
-Wformat @gol
-Wmain @r{(only for C/ObjC and unless} @option{-ffreestanding}@r{)} @gol
+-Wmaybe-uninitialized @gol
-Wmissing-braces @gol
-Wnonnull @gol
-Wparentheses @gol
comment, or whenever a Backslash-Newline appears in a @samp{//} comment.
This warning is enabled by @option{-Wall}.
-@item -Wno-cpp \
+@item -Wno-cpp
@r{(C, Objective-C, C++, Objective-C++ and Fortran only)}
Suppress warning messages emitted by @code{#warning} directives.
floating-point unit implement @code{float} in hardware, but emulate
@code{double} in software. On such a machine, doing computations
using @code{double} values is much more expensive because of the
-overhead required for software emulation.
+overhead required for software emulation.
It is easy to accidentally do computations with @code{double} because
floating-point literals are implicitly of type @code{double}. For
@group
float area(float radius)
@{
- return 3.14159 * radius * radius;
+ return 3.14159 * radius * radius;
@}
@end group
@end smallexample
@end group
@end smallexample
-Also warn for dangerous uses of the
+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.
+inside the conditional expression instead.
This warning is enabled by @option{-Wall}.
computations may be deleted by data flow analysis before the warnings
are printed.
-These warnings are made optional because GCC is not smart
-enough to see all the reasons why the code might be correct
+@item -Wmaybe-uninitialized
+@opindex Wmaybe-uninitialized
+@opindex Wno-maybe-uninitialized
+For an automatic variable, if there exists a path from the function
+entry to a use of the variable that is initialized, but there exist
+some other paths the variable is not initialized, the compiler will
+emit a warning if it can not prove the uninitialized paths do not
+happen at runtime. These warnings are made optional because GCC is
+not smart enough to see all the reasons why the code might be correct
despite appearing to have an error. Here is one example of how
this can happen:
@noindent
If the value of @code{y} is always 1, 2 or 3, then @code{x} is
-always initialized, but GCC doesn't know this. Here is
-another common case:
-
-@smallexample
-@{
- int save_y;
- if (change_y) save_y = y, y = new_y;
- @dots{}
- if (change_y) y = save_y;
-@}
-@end smallexample
-
-@noindent
-This has no bug because @code{save_y} is used only if it is set.
+always initialized, but GCC doesn't know this. To suppress the
+warning, the user needs to provide a default case with assert(0) or
+similar code.
@cindex @code{longjmp} warnings
This option also warns when a non-volatile automatic variable might be
@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
option will increase the size of debugging information by as much as a
factor of two.
+@item -fno-debug-types-section
+@opindex fno-debug-types-section
+@opindex fdebug-types-section
+By default when using DWARF v4 or higher type DIEs will 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 separate
+comdat sections since the linker will then be able to remove duplicates.
+But not all DWARF consumers support .debug_types sections yet.
+
@item -gstabs+
@opindex gstabs+
Produce debugging information in stabs format (if that is supported),
This option works only with DWARF 2.
-@item -fenable-icf-debug
-@opindex fenable-icf-debug
-Generate additional debug information to support identical code folding (ICF).
-This option only works with DWARF version 2 or higher.
-
@item -fno-merge-debug-strings
@opindex fmerge-debug-strings
@opindex fno-merge-debug-strings
optimizations that have a flag are listed in this section.
Most optimizations are only enabled if an @option{-O} level is set on
-the command line. Otherwise they are disabled, even if individual
+the command line. Otherwise they are disabled, even if individual
optimization flags are specified.
Depending on the target and how GCC was configured, a slightly different
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}.
+It turns on @option{-ffast-math} and the Fortran-specific
+@option{-fno-protect-parens}.
If you use multiple @option{-O} options, with or without level numbers,
the last such option is the one that is effective.
@item -fsched-group-heuristic
@opindex fsched-group-heuristic
-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 @option{-fschedule-insns}
+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 @option{-fschedule-insns}
or @option{-fschedule-insns2} or at @option{-O2} or higher.
@item -fsched-critical-path-heuristic
@opindex fsched-critical-path-heuristic
-Enable the critical-path heuristic in the scheduler. This heuristic favors
-instructions on the critical path. This is enabled by default when
-scheduling is enabled, i.e.@: with @option{-fschedule-insns}
+Enable the critical-path heuristic in the scheduler. This heuristic favors
+instructions on the critical path. This is enabled by default when
+scheduling is enabled, i.e.@: with @option{-fschedule-insns}
or @option{-fschedule-insns2} or at @option{-O2} or higher.
@item -fsched-spec-insn-heuristic
@opindex fsched-spec-insn-heuristic
-Enable the speculative instruction heuristic in the scheduler. This
-heuristic favors speculative instructions with greater dependency weakness.
-This is enabled by default when scheduling is enabled, i.e.@:
-with @option{-fschedule-insns} or @option{-fschedule-insns2}
+Enable the speculative instruction heuristic in the scheduler. This
+heuristic favors speculative instructions with greater dependency weakness.
+This is enabled by default when scheduling is enabled, i.e.@:
+with @option{-fschedule-insns} or @option{-fschedule-insns2}
or at @option{-O2} or higher.
@item -fsched-rank-heuristic
@opindex fsched-rank-heuristic
-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 @option{-fschedule-insns} or @option{-fschedule-insns2} or
+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 @option{-fschedule-insns} or @option{-fschedule-insns2} or
at @option{-O2} or higher.
@item -fsched-last-insn-heuristic
@opindex fsched-last-insn-heuristic
-Enable the last-instruction heuristic in the scheduler. This heuristic
+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 @option{-fschedule-insns} or @option{-fschedule-insns2} or
+scheduled. This is enabled by default when scheduling is enabled,
+i.e.@: with @option{-fschedule-insns} or @option{-fschedule-insns2} or
at @option{-O2} or higher.
@item -fsched-dep-count-heuristic
@opindex fsched-dep-count-heuristic
-Enable the dependent-count heuristic in the scheduler. This heuristic
-favors the instruction that has more instructions depending on it.
-This is enabled by default when scheduling is enabled, i.e.@:
-with @option{-fschedule-insns} or @option{-fschedule-insns2} or
+Enable the dependent-count heuristic in the scheduler. This heuristic
+favors the instruction that has more instructions depending on it.
+This is enabled by default when scheduling is enabled, i.e.@:
+with @option{-fschedule-insns} or @option{-fschedule-insns2} or
at @option{-O2} or higher.
@item -freschedule-modulo-scheduled-loops
compilation unit.
Enabled by default at @option{-O} and higher.
-@item -fipa-struct-reorg
-@opindex fipa-struct-reorg
-Perform structure reorganization optimization, that change C-like structures
-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). It works only in whole program
-mode, so it requires @option{-fwhole-program} to be
-enabled. Structures considered @samp{cold} by this transformation are not
-affected (see @option{--param struct-reorg-cold-struct-ratio=@var{value}}).
-
-With this flag, the program debug info reflects a new structure layout.
-
@item -fipa-pta
@opindex fipa-pta
Perform interprocedural pointer analysis and interprocedural modification
GIMPLE files from @file{libfoo.a} and pass 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 linker plugin support and/or do not
+If you are not using a linker with linker plugin support and/or do not
enable linker plugin then the objects inside @file{libfoo.a}
will be extracted and linked as usual, but they will not participate
in the LTO optimization process.
operate. If the program does not require any symbols to be exported, it is
possible to combine @option{-flto} and with @option{-fwhole-program} to allow
the interprocedural optimizers to use more aggressive assumptions which may
-lead to improved optimization opportunities.
+lead to improved optimization opportunities.
Use of @option{-fwhole-program} is not needed when linker plugin is
active (see @option{-fuse-linker-plugin}).
environment variable @env{MAKE} may be used to override the program
used. The default value for @var{n} is 1.
-You can also specify @option{-flto=jobserver} to use GNU make's
-job server mode to determine the number of parallel jobs. This
+You can also specify @option{-flto=jobserver} 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.
The parent Makefile will need a @samp{+} prepended to the command recipe
-for this to work. This will likely only work if @env{MAKE} is
+for this to work. This will likely only work if @env{MAKE} is
GNU make.
This option is disabled by default.
Disabled by default.
@item -fuse-linker-plugin
-Enables the use of linker plugin during link time optimization. This option
-relies on the linker plugin support in linker that is available in @code{gold}
-or in GNU ld 2.21.51 or newer..
-
-This option enables the extraction of object files with GIMPLE bytecode out of
-library archives. This improves the quality of optimization by exposing more
-code the the link time optimizer. This information specify what symbols
-can be accessed externally (by non-LTO object or during dynamic linking).
-Resulting code quality improvements on binaries (and shared libraries that do
-use hidden visibility) is similar to @code{-fwhole-program}. See
-@option{-flto} for a description on the effect of this flag and how to use it.
+Enables the use of a linker plugin during link time optimization. This
+option relies on plugin support in the linker, which is available 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 optimization 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 visibility) are similar to @code{-fwhole-program}.
+See @option{-flto} for a description of the effect of this flag and how to
+use it.
Enabled by default when LTO support in GCC is enabled and GCC was compiled
-with linker supporting plugins (GNU ld or @code{gold}).
+with a linker supporting plugins (GNU ld 2.21 or newer or gold).
@item -fcompare-elim
@opindex fcompare-elim
@var{name} are given in the following table:
@table @gcctabopt
-@item struct-reorg-cold-struct-ratio
-The threshold ratio (as a percentage) between a structure frequency
-and the frequency of the hottest structure in the program. This parameter
-is used by struct-reorg optimization enabled by @option{-fipa-struct-reorg}.
-We say that if the ratio of a structure frequency, calculated by profiling,
-to the hottest structure frequency in the program is less than this
-parameter, then structure reorganization is not applied to this structure.
-The default is 10.
-
@item predictable-branch-outcome
When branch is predicted to be taken with probability lower than this threshold
(in percent), then it is considered well predictable. The default is 10.
internal representation) in a single function that the tree inliner
will consider for inlining. This only affects functions declared
inline and methods implemented in a class declaration (C++).
-The default value is 300.
+The default value is 400.
@item max-inline-insns-auto
When you use @option{-finline-functions} (included in @option{-O3}),
@item hot-bb-frequency-fraction
Select fraction of the entry block frequency of executions of basic block in
-function given basic block needs to have to be considered hot
+function given basic block needs to have to be considered hot.
@item max-predicted-iterations
The maximum number of loop iterations we predict statically. This is useful
The maximum number of best instructions in the ready list that are considered
for renaming in the selective scheduler. The default value is 2.
+@item sms-min-sc
+The minimum value of stage count that swing modulo scheduler will
+generate. The default value is 2.
+
@item max-last-value-rtl
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. The default
The maximum number of namespaces to consult for suggestions when C++
name lookup fails for an identifier. The default is 1000.
+@item max-stores-to-sink
+The maximum number of conditional stores paires that can be sunk. Set to 0
+if either vectorization (@option{-ftree-vectorize}) or if-conversion
+(@option{-ftree-loop-if-convert}) is disabled. The default is 2.
+
@end table
@end table
string. All lines after this directive up to the next directive or
blank line are considered to be the text for the spec string. If this
results in an empty string then the spec will be deleted. (Or, if the
-spec did not exist, then nothing will happened.) Otherwise, if the spec
+spec did not exist, then nothing will happen.) Otherwise, if the spec
does not currently exist a new spec will be created. If the spec does
exist then its contents will be overridden by the text of this
directive, unless the first character of that text is the @samp{+}
@c in Machine Dependent Options
@menu
-* ARC Options::
* ARM Options::
* AVR Options::
* Blackfin Options::
* CRIS Options::
-* CRX Options::
* Darwin Options::
* DEC Alpha Options::
* DEC Alpha/VMS Options::
* M32C Options::
* M32R/D Options::
* M680x0 Options::
-* M68hc1x Options::
* MCore Options::
* MeP Options::
* MicroBlaze Options::
* zSeries Options::
@end menu
-@node ARC Options
-@subsection ARC Options
-@cindex ARC Options
-
-These options are defined for ARC implementations:
-
-@table @gcctabopt
-@item -EL
-@opindex EL
-Compile code for little endian mode. This is the default.
-
-@item -EB
-@opindex EB
-Compile code for big endian mode.
-
-@item -mmangle-cpu
-@opindex mmangle-cpu
-Prepend the name of the cpu to all public symbol names.
-In multiple-processor systems, there are many ARC variants with different
-instruction and register set characteristics. This flag prevents code
-compiled for one cpu to be linked with code compiled for another.
-No facility exists for handling variants that are ``almost identical''.
-This is an all or nothing option.
-
-@item -mcpu=@var{cpu}
-@opindex mcpu
-Compile code for ARC variant @var{cpu}.
-Which variants are supported depend on the configuration.
-All variants support @option{-mcpu=base}, this is the default.
-
-@item -mtext=@var{text-section}
-@itemx -mdata=@var{data-section}
-@itemx -mrodata=@var{readonly-data-section}
-@opindex mtext
-@opindex mdata
-@opindex mrodata
-Put functions, data, and readonly data in @var{text-section},
-@var{data-section}, and @var{readonly-data-section} respectively
-by default. This can be overridden with the @code{section} attribute.
-@xref{Variable Attributes}.
-
-@end table
-
@node ARM Options
@subsection ARM Options
@cindex ARM options
compile your entire program with the same ABI, and link with a
compatible set of libraries.
-@item -mhard-float
-@opindex mhard-float
-Equivalent to @option{-mfloat-abi=hard}.
-
-@item -msoft-float
-@opindex msoft-float
-Equivalent to @option{-mfloat-abi=soft}.
-
@item -mlittle-endian
@opindex mlittle-endian
Generate code for a processor running in little-endian mode. This is
restricting which instructions can be used, it specifies that GCC should
tune the performance of the code as if the target were of the type
specified in this option, but still choosing the instructions that it
-will generate based on the cpu specified by a @option{-mcpu=} option.
+will generate based on the CPU specified by a @option{-mcpu=} option.
For some ARM implementations better performance can be obtained by using
this option.
and has length @code{((pc[-3]) & 0xff000000)}.
@item -mthumb
+@itemx -marm
+@opindex marm
@opindex mthumb
-Generate code for the Thumb instruction set. The default is to
-use the 32-bit ARM instruction set.
-This option automatically enables either 16-bit Thumb-1 or
-mixed 16/32-bit Thumb-2 instructions based on the @option{-mcpu=@var{name}}
-and @option{-march=@var{name}} options. This option is not passed to the
-assembler. If you want to force assembler files to be interpreted as Thumb code,
-either add a @samp{.thumb} directive to the source or pass the @option{-mthumb}
-option directly to the assembler by prefixing it with @option{-Wa}.
+
+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
+configuring GCC with the @option{--with-mode=}@var{state}
+configure option.
@item -mtpcs-frame
@opindex mtpcs-frame
0x40000000 and zero-initialized data at 0x80000000.
@end table
-@node CRX Options
-@subsection CRX Options
-@cindex CRX Options
-
-These options are defined specifically for the CRX ports.
-
-@table @gcctabopt
-
-@item -mmac
-@opindex mmac
-Enable the use of multiply-accumulate instructions. Disabled by default.
-
-@item -mpush-args
-@opindex mpush-args
-Push instructions will be used to pass outgoing arguments when functions
-are called. Enabled by default.
-@end table
-
@node Darwin Options
@subsection Darwin Options
@cindex Darwin options
@code{sqrt} instructions for the 387. Specify this option to avoid
generating those instructions. This option is the default on FreeBSD,
OpenBSD and NetBSD@. This option is overridden when @option{-march}
-indicates that the target cpu will always have an FPU and so the
+indicates that the target CPU will always have an FPU and so the
instruction will not need emulation. As of revision 2.6.1, these
instructions are not generated unless you also use the
@option{-funsafe-math-optimizations} switch.
@opindex mvzeroupper
This option instructs GCC to emit a @code{vzeroupper} instruction
before a transfer of control flow out of the function to minimize
-AVX to SSE transition penalty as well as remove unnecessary zeroupper
+AVX to SSE transition penalty as well as remove unnecessary zeroupper
intrinsics.
@item -mcx16
using the function attribute @samp{ms_abi}/@samp{sysv_abi}.
@xref{Function Attributes}.
+@item -mtls-dialect=@var{type}
+@opindex mtls-dialect
+Generate code to access thread-local storage using the @samp{gnu} or
+@samp{gnu2} conventions. @samp{gnu} is the conservative default;
+@samp{gnu2} is more efficient, but it may add compile- and run-time
+requirements that cannot be satisfied on all systems.
+
@item -mpush-args
@itemx -mno-push-args
@opindex mpush-args
to 255, 8bit unsigned integer divide will be used instead of
32bit/64bit integer divide.
+@item -mavx256-split-unaligned-load
+@item -mavx256-split-unaligned-store
+@opindex avx256-split-unaligned-load
+@opindex avx256-split-unaligned-store
+Split 32-byte AVX unaligned load and store.
+
@end table
These @samp{-m} switches are supported in addition to the above
about addresses and sizes of sections.
@end table
+@node i386 and x86-64 Windows Options
+@subsection i386 and x86-64 Windows Options
+@cindex i386 and x86-64 Windows Options
+
+These additional options are available for Windows targets:
+
+@table @gcctabopt
+@item -mconsole
+@opindex mconsole
+This option is available for Cygwin and MinGW targets. It
+specifies that a console application is to be generated, by
+instructing the linker to set the PE header subsystem type
+required for console applications.
+This is the default behavior for Cygwin and MinGW targets.
+
+@item -mdll
+@opindex mdll
+This option is available for Cygwin and MinGW targets. It
+specifies that a DLL - a dynamic link library - is to be
+generated, enabling the selection of the required runtime
+startup object and entry point.
+
+@item -mnop-fun-dllimport
+@opindex mnop-fun-dllimport
+This option is available for Cygwin and MinGW targets. It
+specifies that the dllimport attribute should be ignored.
+
+@item -mthread
+@opindex mthread
+This option is available for MinGW targets. It specifies
+that MinGW-specific thread support is to be used.
+
+@item -municode
+@opindex municode
+This option is available for mingw-w64 targets. It specifies
+that the UNICODE macro is getting pre-defined and that the
+unicode capable runtime startup code is chosen.
+
+@item -mwin32
+@opindex mwin32
+This option is available for Cygwin and MinGW targets. It
+specifies that the typical Windows pre-defined macros are to
+be set in the pre-processor, but does not influence the choice
+of runtime library/startup code.
+
+@item -mwindows
+@opindex mwindows
+This option is available for Cygwin and MinGW targets. It
+specifies that a GUI application is to be generated by
+instructing the linker to set the PE header subsystem type
+appropriately.
+
+@item -fno-set-stack-executable
+@opindex fno-set-stack-executable
+This option is available for MinGW targets. It specifies that
+the executable flag for stack used by nested functions isn't
+set. This is necessary for binaries running in kernel mode of
+Windows, as there the user32 API, which is used to set executable
+privileges, isn't available.
+
+@item -mpe-aligned-commons
+@opindex mpe-aligned-commons
+This option is available for Cygwin and MinGW targets. It
+specifies that the GNU extension to the PE file format that
+permits the correct alignment of COMMON variables should be
+used when generating code. It will be enabled by default if
+GCC detects that the target assembler found during configuration
+supports the feature.
+@end table
+
+See also under @ref{i386 and x86-64 Options} for standard options.
+
@node IA-64 Options
@subsection IA-64 Options
@cindex IA-64 Options
@end table
-@node M68hc1x Options
-@subsection M68hc1x Options
-@cindex M68hc1x options
-
-These are the @samp{-m} options defined for the 68hc11 and 68hc12
-microcontrollers. The default values for these options depends on
-which style of microcontroller was selected when the compiler was configured;
-the defaults for the most common choices are given below.
-
-@table @gcctabopt
-@item -m6811
-@itemx -m68hc11
-@opindex m6811
-@opindex m68hc11
-Generate output for a 68HC11. This is the default
-when the compiler is configured for 68HC11-based systems.
-
-@item -m6812
-@itemx -m68hc12
-@opindex m6812
-@opindex m68hc12
-Generate output for a 68HC12. This is the default
-when the compiler is configured for 68HC12-based systems.
-
-@item -m68S12
-@itemx -m68hcs12
-@opindex m68S12
-@opindex m68hcs12
-Generate output for a 68HCS12.
-
-@item -mauto-incdec
-@opindex mauto-incdec
-Enable the use of 68HC12 pre and post auto-increment and auto-decrement
-addressing modes.
-
-@item -minmax
-@itemx -mnominmax
-@opindex minmax
-@opindex mnominmax
-Enable the use of 68HC12 min and max instructions.
-
-@item -mlong-calls
-@itemx -mno-long-calls
-@opindex mlong-calls
-@opindex mno-long-calls
-Treat all calls as being far away (near). If calls are assumed to be
-far away, the compiler will use the @code{call} instruction to
-call a function and the @code{rtc} instruction for returning.
-
-@item -mshort
-@opindex mshort
-Consider type @code{int} to be 16 bits wide, like @code{short int}.
-
-@item -msoft-reg-count=@var{count}
-@opindex msoft-reg-count
-Specify the number of pseudo-soft registers which are used for the
-code generation. The maximum number is 32. Using more pseudo-soft
-register may or may not result in better code depending on the program.
-The default is 4 for 68HC11 and 2 for 68HC12.
-
-@end table
-
@node MCore Options
@subsection MCore Options
@cindex MCore options
@item -mcpu=@var{cpu-type}
@opindex mcpu=
Use features of and schedule code for given CPU.
-Supported values are in the format @samp{v@var{X}.@var{YY}.@var{Z}},
-where @var{X} is a major version, @var{YY} is the minor version, and
+Supported values are in the format @samp{v@var{X}.@var{YY}.@var{Z}},
+where @var{X} is a major version, @var{YY} is the minor version, and
@var{Z} is compatibility code. Example values are @samp{v3.00.a},
-@samp{v4.00.b}, @samp{v5.00.a}, @samp{v5.00.b}, @samp{v5.00.b}, @samp{v6.00.a}.
+@samp{v4.00.b}, @samp{v5.00.a}, @samp{v5.00.b}, @samp{v5.00.b}, @samp{v6.00.a}.
@item -mxl-soft-mul
@opindex mxl-soft-mul
Use hardware floating point square root instruction.
@item -mxl-mode-@var{app-model}
-Select application model @var{app-model}. Valid models are
+Select application model @var{app-model}. Valid models are
@table @samp
@item executable
normal executable (default), uses startup code @file{crt0.o}.
@item xmdstub
-for use with Xilinx Microprocessor Debugger (XMD) based
-software intrusive debug agent called xmdstub. This uses startup file
+for use with Xilinx Microprocessor Debugger (XMD) based
+software intrusive debug agent called xmdstub. This uses startup file
@file{crt1.o} and sets the start address of the program to be 0x800.
@item bootstrap
for applications that are loaded using a bootloader.
-This model uses startup file @file{crt2.o} which does not contain a processor
-reset vector handler. This is suitable for transferring control on a
+This model uses startup file @file{crt2.o} which does not contain a processor
+reset vector handler. This is suitable for transferring control on a
processor reset to the bootloader rather than the application.
@item novectors
-for applications that do not require any of the
+for applications that do not require any of the
MicroBlaze vectors. This option may be useful for applications running
within a monitoring application. This model uses @file{crt3.o} as a startup file.
@end table
-Option @option{-xl-mode-@var{app-model}} is a deprecated alias for
+Option @option{-xl-mode-@var{app-model}} is a deprecated alias for
@option{-mxl-mode-@var{app-model}}.
@end table
Tell the MIPS assembler to not run its preprocessor over user
assembler files (with a @samp{.s} suffix) when assembling them.
+@item -mfix-24k
+@item -mno-fix-24k
+@opindex mfix-24k
+@opindex mno-fix-24k
+Work around the 24K E48 (lost data on stores during refill) errata.
+The workarounds are implemented by the assembler rather than by GCC.
+
@item -mfix-r4000
@itemx -mno-fix-r4000
@opindex mfix-r4000
instructions. This option defines the preprocessor macro
@samp{__NO_LIW__}.
+@item -msetlb
+@opindex msetlb
+Allow the compiler to generate the @emph{SETLB} and @emph{Lcc}
+instructions if the target is the @samp{AM33} or later. This is the
+default. This option defines the preprocessor macro @samp{__SETLB__}.
+
+@item -mnosetlb
+@opindex mnosetlb
+Do not allow the compiler to generate @emph{SETLB} or @emph{Lcc}
+instructions. This option defines the preprocessor macro
+@samp{__NO_SETLB__}.
+
@end table
@node PDP-11 Options
On System V.4 and embedded PowerPC systems compile code for the
Linux-based GNU system.
-@item -mcall-gnu
-@opindex mcall-gnu
-On System V.4 and embedded PowerPC systems compile code for the
-Hurd-based GNU system.
-
@item -mcall-freebsd
@opindex mcall-freebsd
On System V.4 and embedded PowerPC systems compile code for the
@opindex -mcpu
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}.
+the specific @var{RX610} CPU. The default is @var{RX600}.
The only difference between @var{RX600} and @var{RX610} is that the
@var{RX610} does not support the @code{MVTIPL} instruction.
@opindex mhitachi
Comply with the calling conventions defined for GCC before the Renesas
conventions were available. This option is the default for all
-targets of the SH toolchain except for @samp{sh-symbianelf}.
+targets of the SH toolchain.
@item -mnomacsave
@opindex mnomacsave
@item -maccumulate-outgoing-args
@opindex maccumulate-outgoing-args
-Reserve space once for outgoing arguments in the function prologue rather
+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.
These switches are supported in addition to the above on Solaris 2:
@table @gcctabopt
-@item -threads
-@opindex threads
-Add support for multithreading using the Solaris threads library. This
-option sets flags for both the preprocessor and linker. This option does
-not affect the thread safety of object code produced by the compiler or
-that of libraries supplied with it.
-
@item -pthreads
@opindex pthreads
Add support for multithreading using the POSIX threads library. This
The same values for @option{-mcpu=@var{cpu_type}} can be used for
@option{-mtune=@var{cpu_type}}, but the only useful values are those
-that select a particular cpu implementation. Those are @samp{cypress},
+that select a particular CPU implementation. Those are @samp{cypress},
@samp{supersparc}, @samp{hypersparc}, @samp{leon}, @samp{f930}, @samp{f934},
@samp{sparclite86x}, @samp{tsc701}, @samp{ultrasparc}, @samp{ultrasparc3},
@samp{niagara}, and @samp{niagara2}.
@item -mv850e2
@opindex mv850e2
Specify that the target processor is the V850E2. The preprocessor
-constants @samp{__v850e2__} will be defined if
+constants @samp{__v850e2__} will be defined if this option is used.
@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 -mv850es
@opindex mv850es
These are listed under @xref{i386 and x86-64 Options}.
-@node i386 and x86-64 Windows Options
-@subsection i386 and x86-64 Windows Options
-@cindex i386 and x86-64 Windows Options
-
-These additional options are available for Windows targets:
-
-@table @gcctabopt
-@item -mconsole
-@opindex mconsole
-This option is available for Cygwin and MinGW targets. It
-specifies that a console application is to be generated, by
-instructing the linker to set the PE header subsystem type
-required for console applications.
-This is the default behavior for Cygwin and MinGW targets.
-
-@item -mdll
-@opindex mdll
-This option is available for Cygwin and MinGW targets. It
-specifies that a DLL - a dynamic link library - is to be
-generated, enabling the selection of the required runtime
-startup object and entry point.
-
-@item -mnop-fun-dllimport
-@opindex mnop-fun-dllimport
-This option is available for Cygwin and MinGW targets. It
-specifies that the dllimport attribute should be ignored.
-
-@item -mthread
-@opindex mthread
-This option is available for MinGW targets. It specifies
-that MinGW-specific thread support is to be used.
-
-@item -municode
-@opindex municode
-This option is available for mingw-w64 targets. It specifies
-that the UNICODE macro is getting pre-defined and that the
-unicode capable runtime startup code is chosen.
-
-@item -mwin32
-@opindex mwin32
-This option is available for Cygwin and MinGW targets. It
-specifies that the typical Windows pre-defined macros are to
-be set in the pre-processor, but does not influence the choice
-of runtime library/startup code.
-
-@item -mwindows
-@opindex mwindows
-This option is available for Cygwin and MinGW targets. It
-specifies that a GUI application is to be generated by
-instructing the linker to set the PE header subsystem type
-appropriately.
-
-@item -fno-set-stack-executable
-@opindex fno-set-stack-executable
-This option is available for MinGW targets. It specifies that
-the executable flag for stack used by nested functions isn't
-set. This is necessary for binaries running in kernel mode of
-Windows, as there the user32 API, which is used to set executable
-privileges, isn't available.
-
-@item -mpe-aligned-commons
-@opindex mpe-aligned-commons
-This option is available for Cygwin and MinGW targets. It
-specifies that the GNU extension to the PE file format that
-permits the correct alignment of COMMON variables should be
-used when generating code. It will be enabled by default if
-GCC detects that the target assembler found during configuration
-supports the feature.
-@end table
-
-See also under @ref{i386 and x86-64 Options} for standard options.
-
@node Xstormy16 Options
@subsection Xstormy16 Options
@cindex Xstormy16 Options
the output of the preprocessor, which is the input to the compiler
proper.
+@item GCC_COMPARE_DEBUG
+@findex GCC_COMPARE_DEBUG
+Setting @env{GCC_COMPARE_DEBUG} is nearly equivalent to passing
+@option{-fcompare-debug} to the compiler driver. See the documentation
+of this option for more details.
+
@item GCC_EXEC_PREFIX
@findex GCC_EXEC_PREFIX
If @env{GCC_EXEC_PREFIX} is set, it specifies a prefix to use in the
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