@gccoptlist{-ansi -std=@var{standard} -fgnu89-inline @gol
-aux-info @var{filename} @gol
-fno-asm -fno-builtin -fno-builtin-@var{function} @gol
--fhosted -ffreestanding -fopenmp -fms-extensions @gol
+-fhosted -ffreestanding -fopenmp -fms-extensions -fplan9-extensions @gol
-trigraphs -no-integrated-cpp -traditional -traditional-cpp @gol
-fallow-single-precision -fcond-mismatch -flax-vector-conversions @gol
-fsigned-bitfields -fsigned-char @gol
-fobjc-direct-dispatch @gol
-fobjc-exceptions @gol
-fobjc-gc @gol
+-fobjc-std=objc1 @gol
-freplace-objc-classes @gol
-fzero-link @gol
-gen-decls @gol
@item Warning Options
@xref{Warning Options,,Options to Request or Suppress Warnings}.
-@gccoptlist{-fsyntax-only -pedantic -pedantic-errors @gol
+@gccoptlist{-fsyntax-only fmax-errors=@var{n} -pedantic @gol
+-pedantic-errors @gol
-w -Wextra -Wall -Waddress -Waggregate-return -Warray-bounds @gol
-Wno-attributes -Wno-builtin-macro-redefined @gol
-Wc++-compat -Wc++0x-compat -Wcast-align -Wcast-qual @gol
-falign-labels[=@var{n}] -falign-loops[=@var{n}] -fassociative-math @gol
-fauto-inc-dec -fbranch-probabilities -fbranch-target-load-optimize @gol
-fbranch-target-load-optimize2 -fbtr-bb-exclusive -fcaller-saves @gol
--fcheck-data-deps -fconserve-stack -fcprop-registers -fcrossjumping @gol
+-fcheck-data-deps -fcombine-stack-adjustments -fconserve-stack @gol
+-fcprop-registers -fcrossjumping @gol
-fcse-follow-jumps -fcse-skip-blocks -fcx-fortran-rules @gol
-fcx-limited-range @gol
-fdata-sections -fdce -fdce @gol
-fdelayed-branch -fdelete-null-pointer-checks -fdse -fdse @gol
-fearly-inlining -fipa-sra -fexpensive-optimizations -ffast-math @gol
-ffinite-math-only -ffloat-store -fexcess-precision=@var{style} @gol
--fforward-propagate -ffunction-sections @gol
+-fforward-propagate -ffp-contract=@var{style} -ffunction-sections @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 @gol
-fipa-pta -fipa-profile -fipa-pure-const -fipa-reference @gol
-fipa-struct-reorg -fira-algorithm=@var{algorithm} @gol
--fira-region=@var{region} -fira-coalesce @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-interchange -floop-strip-mine @gol
--floop-parallelize-all -flto -flto-compression-level -flto-report @gol
--fltrans -fltrans-output-list -fmerge-all-constants -fmerge-constants @gol
--fmodulo-sched -fmodulo-sched-allow-regmoves -fmove-loop-invariants @gol
--fmudflap -fmudflapir -fmudflapth -fno-branch-count-reg @gol
+-floop-block -floop-flatten -floop-interchange -floop-strip-mine @gol
+-floop-parallelize-all -flto -flto-compression-level
+-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
-fno-default-inline @gol
-fno-defer-pop -fno-function-cse -fno-guess-branch-probability @gol
-fno-inline -fno-math-errno -fno-peephole -fno-peephole2 @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[=@var{n}] -fwpa -fuse-linker-plugin @gol
+-fwhole-program -fwpa -fuse-linker-plugin @gol
--param @var{name}=@var{value}
-O -O0 -O1 -O2 -O3 -Os -Ofast}
-mno-wide-multiply -mrtd -malign-double @gol
-mpreferred-stack-boundary=@var{num}
-mincoming-stack-boundary=@var{num} @gol
--mcld -mcx16 -msahf -mmovbe -mcrc32 -mrecip @gol
+-mcld -mcx16 -msahf -mmovbe -mcrc32 -mrecip -mvzeroupper @gol
-mmmx -msse -msse2 -msse3 -mssse3 -msse4.1 -msse4.2 -msse4 -mavx @gol
-maes -mpclmul -mfsgsbase -mrdrnd -mf16c -mfused-madd @gol
--msse4a -m3dnow -mpopcnt -mabm -mfma4 -mxop -mlwp @gol
+-msse4a -m3dnow -mpopcnt -mabm -mbmi -mtbm -mfma4 -mxop -mlwp @gol
-mthreads -mno-align-stringops -minline-all-stringops @gol
-minline-stringops-dynamically -mstringop-strategy=@var{alg} @gol
-mpush-args -maccumulate-outgoing-args -m128bit-long-double @gol
@emph{MN10300 Options}
@gccoptlist{-mmult-bug -mno-mult-bug @gol
--mam33 -mno-am33 @gol
--mam33-2 -mno-am33-2 @gol
+-mno-am33 -mam33 -mam33-2 -mam34 @gol
+-mtune=@var{cpu-type} @gol
-mreturn-pointer-on-d0 @gol
-mno-crt0 -mrelax}
-mint16 -mno-int32 -mfloat32 -mno-float64 @gol
-mfloat64 -mno-float32 -mabshi -mno-abshi @gol
-mbranch-expensive -mbranch-cheap @gol
--msplit -mno-split -munix-asm -mdec-asm}
+-munix-asm -mdec-asm}
@emph{picoChip Options}
@gccoptlist{-mae=@var{ae_type} -mvliw-lookahead=@var{N} @gol
-fno-stack-limit -fsplit-stack @gol
-fleading-underscore -ftls-model=@var{model} @gol
-ftrapv -fwrapv -fbounds-check @gol
--fvisibility}
+-fvisibility -fstrict-volatile-bitfields}
@end table
@menu
accepted with this option. @xref{Unnamed Fields,,Unnamed struct/union
fields within structs/unions}, for details.
+@item -fplan9-extensions
+Accept some non-standard constructs used in Plan 9 code.
+
+This enables @option{-fms-extensions}, permits passing pointers to
+structures with anonymous fields to functions which expect pointers to
+elements of the type of the field, and permits referring to anonymous
+fields declared using a typedef. @xref{Unnamed Fields,,Unnamed
+struct/union fields within structs/unions}, for details. This is only
+supported for C, not C++.
+
@item -trigraphs
@opindex trigraphs
Support ISO C trigraphs. The @option{-ansi} option (and @option{-std}
GNU runtime has a different garbage collection implementation that
does not require special compiler flags.
+@item -fobjc-std=objc1
+@opindex fobjc-std
+Conform to the language syntax of Objective-C 1.0, the language
+recognized by GCC 4.0. This only affects the Objective-C additions to
+the C/C++ language; it does not affect conformance to C/C++ standards,
+which is controlled by the separate C/C++ dialect option flags. When
+this option is used with the Objective-C or Objective-C++ compiler,
+any Objective-C syntax that is not recognized by GCC 4.0 is rejected.
+This is useful if you need to make sure that your Objective-C code can
+be compiled with older versions of GCC.
+
@item -freplace-objc-classes
@opindex freplace-objc-classes
Emit a special marker instructing @command{ld(1)} not to statically link in
@opindex fsyntax-only
Check the code for syntax errors, but don't do anything beyond that.
+@item -fmax-errors=@var{n}
+@opindex fmax-errors
+Limits the maximum number of error messages to @var{n}, at which point
+GCC bails out rather than attempting to continue processing the source
+code. If @var{n} is 0 (the default), there is no limit on the number
+of error messages produced. If @option{-Wfatal-errors} is also
+specified, then @option{-Wfatal-errors} takes precedence over this
+option.
+
@item -w
@opindex w
Inhibit all warning messages.
This option is enabled by default at optimization levels @option{-O},
@option{-O2}, @option{-O3}, @option{-Os}.
+@item -ffp-contract=@var{style}
+@opindex ffp-contract
+@option{-ffp-contract=off} disables floating-point expression contraction.
+@option{-ffp-contract=fast} enables floating-point expression contraction
+such as forming of fused multiply-add operations if the target has
+native support for them.
+@option{-ffp-contract=on} enables floating-point expression contraction
+if allowed by the language standard. This is currently not implemented
+and treated equal to @option{-ffp-contract=off}.
+
+The default is @option{-ffp-contract=fast}.
+
@item -fomit-frame-pointer
@opindex fomit-frame-pointer
Don't keep the frame pointer in a register for functions that
decent code and the smallest size code, and the default value usually
give the best results in most cases and for most architectures.
-@item -fira-coalesce
-@opindex fira-coalesce
-Do optimistic register coalescing. This option might be profitable for
-architectures with big regular register files.
-
@item -fira-loop-pressure
@opindex fira-loop-pressure
Use IRA to evaluate register pressure in loops for decision to move
Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+@item -fcombine-stack-adjustments
+@opindex fcombine-stack-adjustments
+Tracks stack adjustments (pushes and pops) and stack memory references
+and then tries to find ways to combine them.
+
+Enabled by default at @option{-O1} and higher.
+
@item -fconserve-stack
@opindex fconserve-stack
Attempt to minimize stack usage. The compiler will attempt to use less
performance and allow further loop optimizations to take place.
@item -floop-interchange
+@opindex floop-interchange
Perform loop interchange transformations on loops. Interchanging two
nested loops switches the inner and outer loops. For example, given a
loop like:
Graphite loop transformation infrastructure.
@item -floop-strip-mine
+@opindex floop-strip-mine
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
enable the Graphite loop transformation infrastructure.
@item -floop-block
+@opindex 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. The strip length can be changed
are also performed by the code generator CLooG, like index splitting and
dead code elimination in loops.
+@item -floop-flatten
+@opindex floop-flatten
+Removes the loop nesting structure: transforms the loop nest into a
+single loop. This transformation can be useful to vectorize all the
+levels of the loop nest.
+
@item -floop-parallelize-all
+@opindex floop-parallelize-all
Use the Graphite data dependence analysis to identify loops that can
be parallelized. Parallelize all the loops that can be analyzed to
not contain loop carried dependences without checking that it is
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{-flto} or @option{-fwhopr} this flag can be used to
+@option{-flto} this flag can be used to
compile many smaller scale programs since the functions and variables become
local for the whole combined compilation unit, not for the single source file
itself.
This option implies @option{-fwhole-file} for Fortran programs.
-@item -flto
+@item -flto[=@var{n}]
@opindex flto
This option runs the standard link-time optimizer. When invoked
with source code, it generates GIMPLE (one of GCC's internal
optimizations the @option{-flto} flag needs to be passed to both the
compile and the link commands.
+To make whole program optimization effective, it is necesary to make
+certain whole program assumptions. The compiler needs to know
+what functions and variables can be accessed by libraries and runtime
+outside of the link time optimized unit. When supported by the linker,
+the linker plugin (see @option{-fuse-linker-plugin}) passes to the
+compiler information about used and externally visible symbols. When
+the linker plugin is not available, @option{-fwhole-program} should be
+used to allow the compiler to make these assumptions, which will lead
+to more aggressive optimization decisions.
+
Note that when a file is compiled with @option{-flto}, the generated
object file will be larger than a regular object file because it will
contain GIMPLE bytecodes and the usual final code. This means that
will be extracted and linked as usual, but they will not participate
in the LTO optimization process.
-Link time optimizations do not require the presence of the whole
-program to operate. If the program does not require any symbols to
-be exported, it is possible to combine @option{-flto} and
-@option{-fwhopr} with @option{-fwhole-program} to allow the
-interprocedural optimizers to use more aggressive assumptions which
-may lead to improved optimization opportunities.
+Link time optimizations do not require the presence of the whole program to
+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.
+Use of @option{-fwhole-program} is not needed when linker plugin is
+active (see @option{-fuse-linker-plugin}).
Regarding portability: the current implementation of LTO makes no
attempt at generating bytecode that can be ported between different
GCC will not work with an older/newer version of GCC.
Link time optimization does not play well with generating debugging
-information. Combining @option{-flto} or @option{-fwhopr} with
-@option{-g} is experimental.
+information. Combining @option{-flto} with
+@option{-g} is currently experimental and expected to produce wrong
+results.
-This option is disabled by default.
+If you specify the optional @var{n}, the optimization and code
+generation done at link time 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. The default value for @var{n} is 1.
-@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
-all the function bodies in memory, the callgraph is analyzed and
-optimization decisions are made (whole program analysis or WPA). Once
-optimization decisions are made, the callgraph is partitioned and the
-different sections are compiled separately (local transformations or
-LTRANS)@. This process allows optimizations on very large programs
-that otherwise would not fit in memory. This option enables
-@option{-fwpa} and @option{-fltrans} automatically.
-
-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.
-
-You can also specify @option{-fwhopr=jobserver} to use GNU make's
+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 parallel.
+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
GNU make.
-Disabled by default.
-
-@item -fwpa
-@opindex fwpa
-This is an internal option used by GCC when compiling with
-@option{-fwhopr}. You should never need to use it.
-
-This option runs the link-time optimizer in the whole-program-analysis
-(WPA) mode, which reads in summary information from all inputs and
-performs a whole-program analysis based on summary information only.
-It generates object files for subsequent runs of the link-time
-optimizer where individual object files are optimized using both
-summary information from the WPA mode and the actual function bodies.
-It then drives the LTRANS phase.
-
-Disabled by default.
-
-@item -fltrans
-@opindex fltrans
-This is an internal option used by GCC when compiling with
-@option{-fwhopr}. You should never need to use it.
-
-This option runs the link-time optimizer in the local-transformation (LTRANS)
-mode, which reads in output from a previous run of the LTO in WPA mode.
-In the LTRANS mode, LTO optimizes an object and produces the final assembly.
-
-Disabled by default.
-
-@item -fltrans-output-list=@var{file}
-@opindex fltrans-output-list
-This is an internal option used by GCC when compiling with
-@option{-fwhopr}. You should never need to use it.
-
-This option specifies a file to which the names of LTRANS output files are
-written. This option is only meaningful in conjunction with @option{-fwpa}.
+This option is disabled by default.
-Disabled by default.
+@item -flto-partition=@var{alg}
+@opindex flto-partition
+Specify the partitioning algorithm used by the link time optimizer.
+The value is either @code{1to1} to specify a partitioning mirroring
+the original source files or @code{balanced} to specify partitioning
+into equally sized chunks (whenever possible). Specifying @code{none}
+as an algorithm disables partitioning and streaming completely. The
+default value is @code{balanced}.
@item -flto-compression-level=@var{n}
This option specifies the level of compression used for intermediate
language written to LTO object files, and is only meaningful in
-conjunction with LTO mode (@option{-fwhopr}, @option{-flto}). Valid
+conjunction with LTO mode (@option{-flto}). Valid
values are 0 (no compression) to 9 (maximum compression). Values
outside this range are clamped to either 0 or 9. If the option is not
given, a default balanced compression setting is used.
Prints a report with internal details on the workings of the link-time
optimizer. The contents of this report vary from version to version,
it is meant to be useful to GCC developers when processing object
-files in LTO mode (via @option{-fwhopr} or @option{-flto}).
+files in LTO mode (via @option{-flto}).
Disabled by default.
@item early-inlining-insns
Specify growth that early inliner can make. In effect it increases amount of
-inlining for code having large abstraction penalty. The default value is 8.
+inlining for code having large abstraction penalty. The default value is 10.
@item max-early-inliner-iterations
@itemx max-early-inliner-iterations
indirect calls early inliner can resolve. Deeper chains are still handled by
late inlining.
+@item comdat-sharing-probability
+@itemx comdat-sharing-probability
+Probability (in percent) that C++ inline function with comdat visibility
+will be shared acroess multiple compilation units. The default value is 20.
+
@item min-vect-loop-bound
The minimum number of iterations under which a loop will not get vectorized
when @option{-ftree-vectorize} is used. The number of iterations after
@option{devirt-type-list-size} is the maximum number of types it
stores per a single formal parameter of a function.
+@item lto-partitions
+Specify desired nuber of partitions produced during WHOPR copmilation.
+Number of partitions should exceed number of CPUs used for compilatoin.
+Default value is 32.
+
+@item lto-minpartition
+Size of minimal paritition for WHOPR (in estimated instructions).
+This prevents expenses of splitting very small programs into too many
+partitions.
+
@end table
@end table
@item core2
Intel Core2 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3 and SSSE3
instruction set support.
+@item corei7
+Intel Core i7 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1
+and SSE4.2 instruction set support.
@item atom
Intel Atom CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3 and SSSE3
instruction set support.
@itemx -mno-popcnt
@itemx -mabm
@itemx -mno-abm
+@itemx -mbmi
+@itemx -mno-bmi
+@itemx -mtbm
+@itemx -mno-tbm
@opindex mmmx
@opindex mno-mmx
@opindex msse
@opindex mno-3dnow
These switches enable or disable the use of instructions in the MMX,
SSE, SSE2, SSE3, SSSE3, SSE4.1, AVX, AES, PCLMUL, FSGSBASE, RDRND,
-F16C, SSE4A, FMA4, XOP, LWP, ABM or 3DNow!@: extended instruction sets.
+F16C, SSE4A, FMA4, XOP, LWP, ABM, BMI, 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.
instructions can be suppressed with the @option{-mno-cld} compiler option
in this case.
+@item -mvzeroupper
+@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
+intrinsics.
+
@item -mcx16
@opindex mcx16
This option will enable GCC to use CMPXCHG16B instruction in generated code.
@samp{34kc}, @samp{34kf2_1}, @samp{34kf1_1},
@samp{74kc}, @samp{74kf2_1}, @samp{74kf1_1}, @samp{74kf3_2},
@samp{1004kc}, @samp{1004kf2_1}, @samp{1004kf1_1},
-@samp{loongson2e}, @samp{loongson2f},
+@samp{loongson2e}, @samp{loongson2f}, @samp{loongson3a},
@samp{m4k},
@samp{octeon},
@samp{orion},
Do not generate code which uses features specific to the AM33 processor. This
is the default.
+@item -mam33-2
+@opindex mam33-2
+Generate code which uses features specific to the AM33/2.0 processor.
+
+@item -mam34
+@opindex mam34
+Generate code which uses features specific to the AM34 processor.
+
+@item -mtune=@var{cpu-type}
+@opindex mtune
+Use the timing characteristics of the indicated CPU type when
+scheduling instructions. This does not change the targeted processor
+type. The CPU type must be one of @samp{mn10300}, @samp{am33},
+@samp{am33-2} or @samp{am34}.
+
@item -mreturn-pointer-on-d0
@opindex mreturn-pointer-on-d0
When generating a function which returns a pointer, return the pointer
@opindex mbranch-cheap
Do not pretend that branches are expensive. This is the default.
-@item -msplit
-@opindex msplit
-Generate code for a system with split I&D@.
-
-@item -mno-split
-@opindex mno-split
-Generate code for a system without split I&D@. This is the default.
-
@item -munix-asm
@opindex munix-asm
Use Unix assembler syntax. This is the default when configured for
required for console applications.
This is the default behavior for Cygwin and MinGW targets.
-@item -mcygwin
-@opindex mcygwin
-This option is available for Cygwin targets. It specifies that
-the Cygwin internal interface is to be used for predefined
-preprocessor macros, C runtime libraries and related linker
-paths and options. For Cygwin targets this is the default behavior.
-This option is deprecated and will be removed in a future release.
-
-@item -mno-cygwin
-@opindex mno-cygwin
-This option is available for Cygwin targets. It specifies that
-the MinGW internal interface is to be used instead of Cygwin's, by
-setting MinGW-related predefined macros and linker paths and default
-library options.
-This option is deprecated and will be removed in a future release.
-
@item -mdll
@opindex mdll
This option is available for Cygwin and MinGW targets. It
is at @uref{http://gcc.gnu.org/@/wiki/@/Visibility}.
@item -fstrict-volatile-bitfields
+@opindex 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
+anyway) should use a single access of the width of the
+field'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
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
+If the target requires strict alignment, and honoring the field
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.
+If the field has @code{packed} attribute, the access is done without
+honoring the field type. If the field doesn't have @code{packed}
+attribute, the access is done honoring the field type. In both cases,
+GCC assumes that the user knows something about the target hardware
+that it is unaware of.
The default value of this option is determined by the application binary
interface for the target processor.
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