@table @emph
@item Overall Options
@xref{Overall Options,,Options Controlling the Kind of Output}.
-@gccoptlist{-c -S -E -o @var{file} -combine -no-canonical-prefixes @gol
+@gccoptlist{-c -S -E -o @var{file} -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} @gol
+--version -wrapper @@@var{file} -fplugin=@var{file} -fplugin-arg-@var{name}=@var{arg} @gol
-fdump-ada-spec@r{[}-slim@r{]}}
@item C Language Options
@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
-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
--Wunused-but-set-parameter -Wunused-but-set-variable -Wvariadic-macros -Wvla @gol
--Wvolatile-register-var -Wwrite-strings}
+-Wunused-label -Wunused-parameter -Wno-unused-result -Wunused-value @gol
+-Wunused-variable -Wunused-but-set-parameter -Wunused-but-set-variable @gol
+-Wvariadic-macros -Wvla -Wvolatile-register-var -Wwrite-strings}
@item C and Objective-C-only Warning Options
@gccoptlist{-Wbad-function-cast -Wmissing-declarations @gol
@item Optimization Options
@xref{Optimize Options,,Options that Control Optimization}.
-@gccoptlist{
--falign-functions[=@var{n}] -falign-jumps[=@var{n}] @gol
+@gccoptlist{-falign-functions[=@var{n}] -falign-jumps[=@var{n}] @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
--fcse-follow-jumps -fcse-skip-blocks -fcx-fortran-rules -fcx-limited-range @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 -fipa-pta @gol
--fipa-profile -fipa-pure-const -fipa-reference -fipa-struct-reorg @gol
--fira-algorithm=@var{algorithm} @gol
--fira-region=@var{region} -fira-coalesce @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} @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 -fltrans @gol
--fltrans-output-list -fmerge-all-constants -fmerge-constants -fmodulo-sched @gol
--fmodulo-sched-allow-regmoves -fmove-loop-invariants -fmudflap @gol
--fmudflapir -fmudflapth -fno-branch-count-reg -fno-default-inline @gol
+-floop-block -floop-flatten -floop-interchange -floop-strip-mine @gol
+-floop-parallelize-all -flto -flto-compression-level -flto-partition=@var{alg} @gol
+-flto-report -fltrans -fltrans-output-list -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
-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
--fpartial-inlining -fpeel-loops -fpredictive-commoning -fprefetch-loop-arrays @gol
+-fpartial-inlining -fpeel-loops -fpredictive-commoning @gol
+-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
-fsel-sched-pipelining -fsel-sched-pipelining-outer-loops @gol
-fsignaling-nans -fsingle-precision-constant -fsplit-ivs-in-unroller @gol
-fsplit-wide-types -fstack-protector -fstack-protector-all @gol
--fstrict-aliasing -fstrict-overflow -fthread-jumps -ftracer -ftree-bit-ccp @gol
+-fstrict-aliasing -fstrict-overflow -fthread-jumps -ftracer @gol
+-ftree-bit-ccp @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
-mno-fp-ret-in-387 -msoft-float @gol
-mno-wide-multiply -mrtd -malign-double @gol
-mpreferred-stack-boundary=@var{num}
--mincoming-stack-boundary=@var{num}
--mcld -mcx16 -msahf -mmovbe -mcrc32 -mrecip @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
-maes -mpclmul -mfsgsbase -mrdrnd -mf16c -mfused-madd @gol
-msse4a -m3dnow -mpopcnt -mabm -mfma4 -mxop -mlwp @gol
-minline-stringops-dynamically -mstringop-strategy=@var{alg} @gol
-mpush-args -maccumulate-outgoing-args -m128bit-long-double @gol
-m96bit-long-double -mregparm=@var{num} -msseregparm @gol
--mveclibabi=@var{type} -mpc32 -mpc64 -mpc80 -mstackrealign @gol
+-mveclibabi=@var{type} -mvect8-ret-in-mem @gol
+-mpc32 -mpc64 -mpc80 -mstackrealign @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
-mmult -mno-opts -mrepeat -ms -msatur -msdram -msim -msimnovec -mtf @gol
-mtiny=@var{n}}
+@emph{MicroBlaze Options}
+@gccoptlist{-msoft-float -mhard-float -msmall-divides -mcpu=@var{cpu} @gol
+-mmemcpy -mxl-soft-mul -mxl-soft-div -mxl-barrel-shift @gol
+-mxl-pattern-compare -mxl-stack-check -mxl-gp-opt -mno-clearbss @gol
+-mxl-multiply-high -mxl-float-convert -mxl-float-sqrt @gol
+-mxl-mode-@var{app-model}}
+
@emph{MIPS Options}
@gccoptlist{-EL -EB -march=@var{arch} -mtune=@var{arch} @gol
-mips1 -mips2 -mips3 -mips4 -mips32 -mips32r2 @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}
-msplit -mno-split -munix-asm -mdec-asm}
@emph{picoChip Options}
-@gccoptlist{-mae=@var{ae_type} -mvliw-lookahead=@var{N}
+@gccoptlist{-mae=@var{ae_type} -mvliw-lookahead=@var{N} @gol
-msymbol-as-address -mno-inefficient-warnings}
@emph{PowerPC Options}
-madjust-unroll -mindexed-addressing -mgettrcost=@var{number} -mpt-fixed @gol
-maccumulate-outgoing-args -minvalid-symbols}
+@emph{Solaris 2 Options}
+@gccoptlist{-mimpure-text -mno-impure-text @gol
+-threads -pthreads -pthread}
+
@emph{SPARC Options}
@gccoptlist{-mcpu=@var{cpu-type} @gol
-mtune=@var{cpu-type} @gol
-mfaster-structs -mno-faster-structs @gol
-mfpu -mno-fpu -mhard-float -msoft-float @gol
-mhard-quad-float -msoft-quad-float @gol
--mimpure-text -mno-impure-text -mlittle-endian @gol
+-mlittle-endian @gol
-mstack-bias -mno-stack-bias @gol
-munaligned-doubles -mno-unaligned-doubles @gol
--mv8plus -mno-v8plus -mvis -mno-vis
--threads -pthreads -pthread}
+-mv8plus -mno-v8plus -mvis -mno-vis}
@emph{SPU Options}
@gccoptlist{-mwarn-reloc -merror-reloc @gol
@emph{i386 and x86-64 Windows Options}
@gccoptlist{-mconsole -mcygwin -mno-cygwin -mdll
--mnop-fun-dllimport -mthread -municode -mwin32 -mwindows
--fno-set-stack-executable}
+-mnop-fun-dllimport -mthread @gol
+-municode -mwin32 -mwindows -fno-set-stack-executable}
@emph{Xstormy16 Options}
@gccoptlist{-msim}
-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 @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
the assembler is unable to read from a pipe; but the GNU assembler has
no trouble.
-@item -combine
-@opindex combine
-If you are compiling multiple source files, this option tells the driver
-to pass all the source files to the compiler at once (for those
-languages for which the compiler can handle this). This will allow
-intermodule analysis (IMA) to be performed by the compiler. Currently the only
-language for which this is supported is C@. If you pass source files for
-multiple languages to the driver, using this option, the driver will invoke
-the compiler(s) that support IMA once each, passing each compiler all the
-source files appropriate for it. For those languages that do not support
-IMA this option will be ignored, and the compiler will be invoked once for
-each source file in that language. If you use this option in conjunction
-with @option{-save-temps}, the compiler will generate multiple
-pre-processed files
-(one for each source file), but only one (combined) @file{.o} or
-@file{.s} file.
-
@item --help
@opindex help
Print (on the standard output) a description of the command line options
@item -fopenmp
@opindex fopenmp
-@cindex openmp parallel
+@cindex OpenMP parallel
Enable handling of OpenMP directives @code{#pragma omp} in C/C++ and
@code{!$omp} in Fortran. When @option{-fopenmp} is specified, the
compiler generates parallel code according to the OpenMP Application
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}
@item -Woverloaded-virtual @r{(C++ and Objective-C++ only)}
@opindex Woverloaded-virtual
@opindex Wno-overloaded-virtual
-@cindex overloaded virtual fn, warning
-@cindex warning for overloaded virtual fn
+@cindex overloaded virtual function, warning
+@cindex warning for overloaded virtual function
Warn when a function declaration hides virtual functions from a
base class. For example, in:
@item -fno-nil-receivers
@opindex fno-nil-receivers
-Assume that all Objective-C message dispatches (e.g.,
-@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.
+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.
@item -fobjc-call-cxx-cdtors
@opindex fobjc-call-cxx-cdtors
special @code{- (void) .cxx_destruct} method that will run
all such default destructors, in reverse order.
-The @code{- (id) .cxx_construct} and/or @code{- (void) .cxx_destruct} methods
-thusly generated will only operate on instance variables declared in the
-current Objective-C class, and not those inherited from superclasses. It
-is the responsibility of the Objective-C runtime to invoke all such methods
-in an object's inheritance hierarchy. The @code{- (id) .cxx_construct} methods
-will be invoked by the runtime immediately after a new object
-instance is allocated; the @code{- (void) .cxx_destruct} methods will
-be invoked immediately before the runtime deallocates an object instance.
+The @code{- (id) .cxx_construct} and @code{- (void) .cxx_destruct}
+methods thusly generated will only operate on instance variables
+declared in the current Objective-C class, and not those inherited
+from superclasses. It is the responsibility of the Objective-C
+runtime to invoke all such methods in an object's inheritance
+hierarchy. The @code{- (id) .cxx_construct} methods will be invoked
+by the runtime immediately after a new object instance is allocated;
+the @code{- (void) .cxx_destruct} methods will be invoked immediately
+before the runtime deallocates an object instance.
As of this writing, only the NeXT runtime on Mac OS X 10.4 and later has
support for invoking the @code{- (id) .cxx_construct} and
@item -fobjc-exceptions
@opindex fobjc-exceptions
-Enable syntactic support for structured exception handling in Objective-C,
-similar to what is offered by C++ and Java. This option is
-unavailable in conjunction with the NeXT runtime on Mac OS X 10.2 and
-earlier.
-
-@smallexample
- @@try @{
- @dots{}
- @@throw expr;
- @dots{}
- @}
- @@catch (AnObjCClass *exc) @{
- @dots{}
- @@throw expr;
- @dots{}
- @@throw;
- @dots{}
- @}
- @@catch (AnotherClass *exc) @{
- @dots{}
- @}
- @@catch (id allOthers) @{
- @dots{}
- @}
- @@finally @{
- @dots{}
- @@throw expr;
- @dots{}
- @}
-@end smallexample
-
-The @code{@@throw} statement may appear anywhere in an Objective-C or
-Objective-C++ program; when used inside of a @code{@@catch} block, the
-@code{@@throw} may appear without an argument (as shown above), in which case
-the object caught by the @code{@@catch} will be rethrown.
-
-Note that only (pointers to) Objective-C objects may be thrown and
-caught using this scheme. When an object is thrown, it will be caught
-by the nearest @code{@@catch} clause capable of handling objects of that type,
-analogously to how @code{catch} blocks work in C++ and Java. A
-@code{@@catch(id @dots{})} clause (as shown above) may also be provided to catch
-any and all Objective-C exceptions not caught by previous @code{@@catch}
-clauses (if any).
-
-The @code{@@finally} clause, if present, will be executed upon exit from the
-immediately preceding @code{@@try @dots{} @@catch} section. This will happen
-regardless of whether any exceptions are thrown, caught or rethrown
-inside the @code{@@try @dots{} @@catch} section, analogously to the behavior
-of the @code{finally} clause in Java.
-
-There are several caveats to using the new exception mechanism:
-
-@itemize @bullet
-@item
-Although currently designed to be binary compatible with @code{NS_HANDLER}-style
-idioms provided by the @code{NSException} class, the new
-exceptions can only be used on Mac OS X 10.3 (Panther) and later
-systems, due to additional functionality needed in the (NeXT) Objective-C
-runtime.
-
-@item
-As mentioned above, the new exceptions do not support handling
-types other than Objective-C objects. Furthermore, when used from
-Objective-C++, the Objective-C exception model does not interoperate with C++
-exceptions at this time. This means you cannot @code{@@throw} an exception
-from Objective-C and @code{catch} it in C++, or vice versa
-(i.e., @code{throw @dots{} @@catch}).
-@end itemize
-
-The @option{-fobjc-exceptions} switch also enables the use of synchronization
-blocks for thread-safe execution:
-
-@smallexample
- @@synchronized (ObjCClass *guard) @{
- @dots{}
- @}
-@end smallexample
-
-Upon entering the @code{@@synchronized} block, a thread of execution shall
-first check whether a lock has been placed on the corresponding @code{guard}
-object by another thread. If it has, the current thread shall wait until
-the other thread relinquishes its lock. Once @code{guard} becomes available,
-the current thread will place its own lock on it, execute the code contained in
-the @code{@@synchronized} block, and finally relinquish the lock (thereby
-making @code{guard} available to other threads).
-
-Unlike Java, Objective-C does not allow for entire methods to be marked
-@code{@@synchronized}. Note that throwing exceptions out of
-@code{@@synchronized} blocks is allowed, and will cause the guarding object
-to be unlocked properly.
+Enable syntactic support for structured exception handling in
+Objective-C, similar to what is offered by C++ and Java. This option
+is required to use the Objective-C keywords @code{@@try},
+@code{@@throw}, @code{@@catch}, @code{@@finally} and
+@code{@@synchronized}. This option is available with both the GNU
+runtime and the NeXT runtime (but not available in conjunction with
+the NeXT runtime on Mac OS X 10.2 and earlier).
@item -fobjc-gc
@opindex fobjc-gc
-Enable garbage collection (GC) in Objective-C and Objective-C++ programs.
+Enable garbage collection (GC) in Objective-C and Objective-C++
+programs. This option is only available with the NeXT runtime; the
+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
suppresses this behavior and causes calls to @code{objc_getClass("@dots{}")}
to be retained. This is useful in Zero-Link debugging mode, since it allows
for individual class implementations to be modified during program execution.
+The GNU runtime currently always retains calls to @code{objc_get_class("@dots{}")}
+regardless of command line options.
@item -gen-decls
@opindex gen-decls
over the precise meaning of the sequence point rules in subtle cases.
Links to discussions of the problem, including proposed formal
definitions, may be found on the GCC readings page, at
-@w{@uref{http://gcc.gnu.org/readings.html}}.
+@uref{http://gcc.gnu.org/@/readings.html}.
This warning is enabled by @option{-Wall} for C and C++.
@option{-femit-struct-debug-reduced} and @option{-femit-struct-debug-baseonly},
which will serve for most needs.
-A specification has the syntax
+A specification has the syntax@*
[@samp{dir:}|@samp{ind:}][@samp{ord:}|@samp{gen:}](@samp{any}|@samp{sys}|@samp{base}|@samp{none})
The optional first word limits the specification to
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
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} and @option{-combine} to be
+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}}).
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{-combine}, @option{-flto} or @option{-fwhopr} this flag can be used to
+@option{-flto} or @option{-fwhopr} 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.
Disabled by default.
+@item -flto-partition=@var{alg}
+@opindex flto-partition
+Specify partitioning algorithm used by @option{-fwhopr} mode. The value is
+either @code{1to1} to specify partitioning corresponding to source files
+or @code{balanced} to specify partitioning into, if possible, equally sized
+chunks. The default value is @code{balanced}.
+
@item -fwpa
@opindex fwpa
This is an internal option used by GCC when compiling with
@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
@table @code
@item %include <@var{file}>
-@cindex %include
+@cindex @code{%include}
Search for @var{file} and insert its text at the current point in the
specs file.
@item %include_noerr <@var{file}>
-@cindex %include_noerr
+@cindex @code{%include_noerr}
Just like @samp{%include}, but do not generate an error message if the include
file cannot be found.
@item %rename @var{old_name} @var{new_name}
-@cindex %rename
+@cindex @code{%rename}
Rename the spec string @var{old_name} to @var{new_name}.
@end table
* M68hc1x Options::
* MCore Options::
* MeP Options::
+* MicroBlaze Options::
* MIPS Options::
* MMIX Options::
* MN10300 Options::
* S/390 and zSeries Options::
* Score Options::
* SH Options::
+* Solaris 2 Options::
* SPARC Options::
* SPU Options::
* System V Options::
@itemx -dynamic
@itemx -exported_symbols_list
@itemx -filelist
+@need 800
@itemx -flat_namespace
@itemx -force_flat_namespace
@itemx -headerpad_max_install_names
@itemx -multi_module
@itemx -multiply_defined
@itemx -multiply_defined_unused
+@need 800
@itemx -noall_load
@itemx -no_dead_strip_inits_and_terms
@itemx -nofixprebinding
@itemx -prebind
@itemx -prebind_all_twolevel_modules
@itemx -private_bundle
+@need 800
@itemx -read_only_relocs
@itemx -sectalign
@itemx -sectobjectsymbols
@itemx -sectorder
@itemx -segaddr
@itemx -segs_read_only_addr
+@need 800
@itemx -segs_read_write_addr
@itemx -seg_addr_table
@itemx -seg_addr_table_filename
@itemx -single_module
@itemx -static
@itemx -sub_library
+@need 800
@itemx -sub_umbrella
@itemx -twolevel_namespace
@itemx -umbrella
@var{cpu-type} are:
@table @emph
@item generic
-Produce code optimized for the most common IA32/AMD64/EM64T processors.
+Produce code optimized for the most common IA32/@/AMD64/@/EM64T processors.
If you know the CPU on which your code will run, then you should use
the corresponding @option{-mtune} option instead of
@option{-mtune=generic}. But, if you do not know exactly what CPU users
@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.
modules with the same value, including any libraries. This includes
the system libraries and startup modules.
+@item -mvect8-ret-in-mem
+@opindex mvect8-ret-in-mem
+Return 8-byte vectors in memory instead of MMX registers. This is the
+default on Solaris~8 and 9 and VxWorks to match the ABI of the Sun
+Studio compilers until version 12. Later compiler versions (starting
+with Studio 12 Update~1) follow the ABI used by other x86 targets, which
+is the default on Solaris~10 and later. @emph{Only} use this option if
+you need to remain compatible with existing code produced by those
+previous compiler versions or older versions of GCC.
+
@item -mpc32
@itemx -mpc64
@itemx -mpc80
@itemx -mssse3
@itemx -mno-ssse3
@itemx -msse4.1
+@need 800
@itemx -mno-sse4.1
@itemx -msse4.2
@itemx -mno-sse4.2
@itemx -maes
@itemx -mno-aes
@itemx -mpclmul
+@need 800
@itemx -mno-pclmul
@itemx -mfsgsbase
@itemx -mno-fsgsbase
@itemx -msse4a
@itemx -mno-sse4a
@itemx -mfma4
+@need 800
@itemx -mno-fma4
@itemx -mxop
@itemx -mno-xop
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.
@end table
+@node MicroBlaze Options
+@subsection MicroBlaze Options
+@cindex MicroBlaze Options
+
+@table @gcctabopt
+
+@item -msoft-float
+@opindex msoft-float
+Use software emulation for floating point (default).
+
+@item -mhard-float
+@opindex mhard-float
+Use hardware floating point instructions.
+
+@item -mmemcpy
+@opindex mmemcpy
+Do not optimize block moves, use @code{memcpy}.
+
+@item -mno-clearbss
+@opindex mno-clearbss
+This option is deprecated. Use @option{-fno-zero-initialized-in-bss} instead.
+
+@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
+@var{Z} is compatiblity 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}.
+
+@item -mxl-soft-mul
+@opindex mxl-soft-mul
+Use software multiply emulation (default).
+
+@item -mxl-soft-div
+@opindex mxl-soft-div
+Use software emulation for divides (default).
+
+@item -mxl-barrel-shift
+@opindex mxl-barrel-shift
+Use the hardware barrel shifter.
+
+@item -mxl-pattern-compare
+@opindex mxl-pattern-compare
+Use pattern compare instructions.
+
+@item -msmall-divides
+@opindex msmall-divides
+Use table lookup optimization for small signed integer divisions.
+
+@item -mxl-stack-check
+@opindex mxl-stack-check
+This option is deprecated. Use -fstack-check instead.
+
+@item -mxl-gp-opt
+@opindex mxl-gp-opt
+Use GP relative sdata/sbss sections.
+
+@item -mxl-multiply-high
+@opindex mxl-multiply-high
+Use multiply high instructions for high part of 32x32 multiply.
+
+@item -mxl-float-convert
+@opindex mxl-float-convert
+Use hardware floating point converstion instructions.
+
+@item -mxl-float-sqrt
+@opindex mxl-float-sqrt
+Use hardware floating point square root instruction.
+
+@item -mxl-mode-@var{app-model}
+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
+@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
+processor reset to the bootloader rather than the application.
+
+@item novectors
+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{-mxl-mode-@var{app-model}}.
+
+@end table
+
@node MIPS Options
@subsection MIPS Options
@cindex MIPS options
can use @option{-mgp32} to get 32-bit code instead.
For information about the O64 ABI, see
-@w{@uref{http://gcc.gnu.org/projects/mipso64-abi.html}}.
+@uref{http://gcc.gnu.org/@/projects/@/mipso64-abi.html}.
GCC supports a variant of the o32 ABI in which floating-point registers
are 64 rather than 32 bits wide. You can select this combination with
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
@itemx -mno-powerpc-gpopt
@itemx -mpowerpc-gfxopt
@itemx -mno-powerpc-gfxopt
+@need 800
@itemx -mpowerpc64
@itemx -mno-powerpc64
@itemx -mmfcrf
@itemx -mno-popcntd
@itemx -mfprnd
@itemx -mno-fprnd
+@need 800
@itemx -mcmpb
@itemx -mno-cmpb
@itemx -mmfpgpr
of symbol loads. The default is @option{-mno-invalid-symbols}.
@end table
+@node Solaris 2 Options
+@subsection Solaris 2 Options
+@cindex Solaris 2 options
+
+These @samp{-m} options are supported on Solaris 2:
+
+@table @gcctabopt
+@item -mimpure-text
+@opindex mimpure-text
+@option{-mimpure-text}, used in addition to @option{-shared}, tells
+the compiler to not pass @option{-z text} to the linker when linking a
+shared object. Using this option, you can link position-dependent
+code into a shared object.
+
+@option{-mimpure-text} suppresses the ``relocations remain against
+allocatable but non-writable sections'' linker error message.
+However, the necessary relocations will trigger copy-on-write, and the
+shared object is not actually shared across processes. Instead of
+using @option{-mimpure-text}, you should compile all source code with
+@option{-fpic} or @option{-fPIC}.
+
+@end table
+
+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
+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 -pthread
+@opindex pthread
+This is a synonym for @option{-pthreads}.
+@end table
+
@node SPARC Options
@subsection SPARC Options
@cindex SPARC options
acknowledges that their resulting code will not be directly in line with
the rules of the ABI@.
-@item -mimpure-text
-@opindex mimpure-text
-@option{-mimpure-text}, used in addition to @option{-shared}, tells
-the compiler to not pass @option{-z text} to the linker when linking a
-shared object. Using this option, you can link position-dependent
-code into a shared object.
-
-@option{-mimpure-text} suppresses the ``relocations remain against
-allocatable but non-writable sections'' linker error message.
-However, the necessary relocations will trigger copy-on-write, and the
-shared object is not actually shared across processes. Instead of
-using @option{-mimpure-text}, you should compile all source code with
-@option{-fpic} or @option{-fPIC}.
-
-This option is only available on SunOS and Solaris.
-
@item -mcpu=@var{cpu_type}
@opindex mcpu
Set the instruction set, register set, and instruction scheduling parameters
Otherwise, assume no such offset is present.
@end table
-These switches are supported in addition to the above on Solaris:
-
-@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
-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 -pthread
-@opindex pthread
-This is a synonym for @option{-pthreads}.
-@end table
-
@node SPU Options
@subsection SPU Options
@cindex SPU options
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
if the @var{file} parameter is a substring of the file name, it is
considered to be a match.
-For example,
-@code{-finstrument-functions-exclude-file-list=/bits/stl,include/sys}
+For example:
+
+@smallexample
+-finstrument-functions-exclude-file-list=/bits/stl,include/sys
+@end smallexample
+
+@noindent
will exclude any inline function defined in files whose pathnames
contain @code{/bits/stl} or @code{include/sys}.
@option{-Wl,--defsym,__stack_limit=0x7ffe0000} to enforce a stack limit
of 128KB@. Note that this may only work with the GNU linker.
+@item -fsplit-stack
+@opindex fsplit-stack
+Generate code to automatically split the stack before it overflows.
+The resulting program has a discontiguous stack which can only
+overflow if the program is unable to allocate any more memory. This
+is most useful when running threaded programs, as it is no longer
+necessary to calculate a good stack size to use for each thread. This
+is currently only implemented for the i386 and x86_64 backends running
+GNU/Linux.
+
+When code compiled with @option{-fsplit-stack} calls code compiled
+without @option{-fsplit-stack}, there may not be much stack space
+available for the latter code to run. If compiling all code,
+including library code, with @option{-fsplit-stack} is not an option,
+then the linker can fix up these calls so that the code compiled
+without @option{-fsplit-stack} always has a large stack. Support for
+this is implemented in the gold linker in GNU binutils release 2.21
+and later.
+
@item -fleading-underscore
@opindex fleading-underscore
This option and its counterpart, @option{-fno-leading-underscore}, forcibly
the DSOs.
An overview of these techniques, their benefits and how to use them
-is at @w{@uref{http://gcc.gnu.org/wiki/Visibility}}.
+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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