-Werror -Werror=* @gol
-Wfatal-errors -Wfloat-equal -Wformat -Wformat=2 @gol
-Wno-format-extra-args -Wformat-nonliteral @gol
--Wformat-security -Wformat-y2k @gol
+-Wformat-security -Wformat-y2k -Wignored-qualifiers @gol
-Wimplicit -Wimplicit-function-declaration -Wimplicit-int @gol
-Wimport -Wno-import -Winit-self -Winline @gol
-Wno-int-to-pointer-cast -Wno-invalid-offsetof @gol
@item Optimization Options
@xref{Optimize Options,,Options that Control Optimization}.
-@gccoptlist{-falign-functions=@var{n} -falign-jumps=@var{n} @gol
--falign-labels=@var{n} -falign-loops=@var{n} @gol
--fbounds-check -fmudflap -fmudflapth -fmudflapir @gol
--fbranch-probabilities -fprofile-values -fvpt -fbranch-target-load-optimize @gol
--fbranch-target-load-optimize2 -fbtr-bb-exclusive @gol
--fcaller-saves -fcprop-registers -fcse-follow-jumps @gol
--fcse-skip-blocks -fcx-limited-range -fdata-sections @gol
--fdelayed-branch -fdelete-null-pointer-checks -fearly-inlining @gol
--fexpensive-optimizations -ffast-math -ffloat-store @gol
--fforce-addr -fforward-propagate -ffunction-sections @gol
--fgcse -fgcse-lm -fgcse-sm -fgcse-las -fgcse-after-reload @gol
--fcrossjumping -fif-conversion -fif-conversion2 @gol
--finline-functions -finline-functions-called-once @gol
--finline-small-functions -finline-limit=@var{n} -fkeep-inline-functions @gol
--fkeep-static-consts -fmerge-constants -fmerge-all-constants @gol
--fmodulo-sched -fmodulo-sched-allow-regmoves -fno-branch-count-reg @gol
--fno-default-inline -fno-defer-pop -fmove-loop-invariants @gol
--fno-function-cse -fno-guess-branch-probability @gol
--fno-inline -fno-math-errno -fno-peephole -fno-peephole2 @gol
--funsafe-math-optimizations -funsafe-loop-optimizations @gol
--ffinite-math-only -fno-signed-zeros @gol
--fno-toplevel-reorder -fno-trapping-math -fno-zero-initialized-in-bss @gol
--fomit-frame-pointer -foptimize-register-move @gol
--foptimize-sibling-calls -fpredictive-commoning -fprefetch-loop-arrays @gol
--fprofile-generate -fprofile-use @gol
--fregmove -frename-registers @gol
--freorder-blocks -freorder-blocks-and-partition -freorder-functions @gol
--frerun-cse-after-loop @gol
--frounding-math -frtl-abstract-sequences @gol
--fschedule-insns -fschedule-insns2 @gol
--fno-sched-interblock -fno-sched-spec -fsched-spec-load @gol
--fsched-spec-load-dangerous @gol
--fsched-stalled-insns=@var{n} -fsched-stalled-insns-dep=@var{n} @gol
--fsched2-use-superblocks @gol
--fsched2-use-traces -fsee -freschedule-modulo-scheduled-loops @gol
--fsection-anchors -fsignaling-nans -fsingle-precision-constant @gol
--fno-split-wide-types -fstack-protector -fstack-protector-all @gol
--fstrict-aliasing -fstrict-overflow -ftracer -fthread-jumps @gol
--funroll-all-loops -funroll-loops -fpeel-loops @gol
--fsplit-ivs-in-unroller -funswitch-loops @gol
--fvariable-expansion-in-unroller -ftree-reassoc @gol
--ftree-pre -ftree-ccp -ftree-dce -ftree-loop-optimize @gol
--ftree-loop-linear -ftree-loop-im -ftree-loop-ivcanon -fivopts @gol
--fcheck-data-deps -ftree-parallelize-loops @gol
--ftree-dominator-opts -ftree-dse -ftree-copyrename -ftree-sink @gol
--ftree-ch -ftree-sra -ftree-ter -ftree-fre -ftree-vectorize @gol
--ftree-vect-loop-version -fvect-cost-model -ftree-salias -fipa-pta -fweb @gol
--ftree-copy-prop -ftree-store-ccp -ftree-store-copy-prop -fwhole-program @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 -fcprop-registers -fcrossjumping -fcse-follow-jumps @gol
+-fcse-skip-blocks -fcx-limited-range -fdata-sections -fdce -fdce @gol
+-fdelayed-branch -fdelete-null-pointer-checks -fdse -fdse @gol
+-fearly-inlining -fexpensive-optimizations -ffast-math @gol
+-ffinite-math-only -ffloat-store -fforward-propagate @gol
+-ffunction-sections -fgcse -fgcse-after-reload -fgcse-las -fgcse-lm @gol
+-fgcse-sm -fif-conversion -fif-conversion2 -finline-functions @gol
+-finline-functions-called-once -finline-limit=@var{n} @gol
+-finline-small-functions -fipa-cp -fipa-marix-reorg -fipa-pta @gol
+-fipa-pure-const -fipa-reference -fipa-struct-reorg @gol
+-fipa-type-escape -fivopts -fkeep-inline-functions -fkeep-static-consts @gol
+-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
+-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
+-fpeel-loops -fpredictive-commoning -fprefetch-loop-arrays @gol
+-fprofile-generate -fprofile-use -fprofile-values -freciprocal-math @gol
+-fregmove -frename-registers -freorder-blocks @gol
+-freorder-blocks-and-partition -freorder-functions @gol
+-frerun-cse-after-loop -freschedule-modulo-scheduled-loops @gol
+-frounding-math -frtl-abstract-sequences -fsched2-use-superblocks @gol
+-fsched2-use-traces -fsched-spec-load -fsched-spec-load-dangerous @gol
+-fsched-stalled-insns-dep[=@var{n}] -fsched-stalled-insns[=@var{n}] @gol
+-fschedule-insns -fschedule-insns2 -fsection-anchors -fsee @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-ccp @gol
+-ftree-ch -ftree-copy-prop -ftree-copyrename -ftree-dce @gol
+-ftree-dominator-opts -ftree-dse -ftree-fre -ftree-loop-im @gol
+-ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol
+-ftree-parallelize-loops=@var{n} -ftree-pre -ftree-reassoc -ftree-salias @gol
+-ftree-sink -ftree-sra -ftree-store-ccp -ftree-ter @gol
+-ftree-vect-loop-version -ftree-vectorize -ftree-vrp -funit-at-a-time @gol
+-funroll-all-loops -funroll-loops -funsafe-loop-optimizations @gol
+-funsafe-math-optimizations -funswitch-loops @gol
+-fvariable-expansion-in-unroller -fvect-cost-model -fvpt -fweb @gol
+-fwhole-program @gol
--param @var{name}=@var{value}
-O -O0 -O1 -O2 -O3 -Os}
-mpowerpc-gpopt -mno-powerpc-gpopt @gol
-mpowerpc-gfxopt -mno-powerpc-gfxopt @gol
-mmfcrf -mno-mfcrf -mpopcntb -mno-popcntb -mfprnd -mno-fprnd @gol
--mcmpb -mno-cmpb -mmfpgpr -mno-mfpgpr -mdfp -mno-dfp @gol
+-mcmpb -mno-cmpb -mmfpgpr -mno-mfpgpr -mhard-dfp -mno-hard-dfp @gol
-mnew-mnemonics -mold-mnemonics @gol
-mfull-toc -mminimal-toc -mno-fp-in-toc -mno-sum-in-toc @gol
-m64 -m32 -mxl-compat -mno-xl-compat -mpe @gol
-fshort-double -fshort-wchar @gol
-fverbose-asm -fpack-struct[=@var{n}] -fstack-check @gol
-fstack-limit-register=@var{reg} -fstack-limit-symbol=@var{sym} @gol
--fargument-alias -fargument-noalias @gol
--fargument-noalias-global -fargument-noalias-anything
+-fno-stack-limit -fargument-alias -fargument-noalias @gol
+-fargument-noalias-global -fargument-noalias-anything @gol
-fleading-underscore -ftls-model=@var{model} @gol
-ftrapv -fwrapv -fbounds-check @gol
-fvisibility}
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
-Program Interface v2.5 @w{@uref{http://www.openmp.org/}}.
+Program Interface v2.5 @w{@uref{http://www.openmp.org/}}. This option
+implies @option{-pthread}, and thus is only supported on targets that
+have support for @option{-pthread}.
@item -fms-extensions
@opindex fms-extensions
@gccoptlist{-Wclobbered @gol
-Wempty-body @gol
+-Wignored-qualifiers @gol
-Wmissing-field-initializers @gol
-Wmissing-parameter-type @r{(C only)} @gol
-Wold-style-declaration @r{(C only)} @gol
Same as @option{-Wimplicit-int} and @option{-Wimplicit-function-declaration}.
This warning is enabled by @option{-Wall}.
+@item -Wignored-qualifiers
+@opindex Wignored-qualifiers
+@opindex Wno-ignored-qualifiers
+Warn if the return type of a function has a type qualifier
+such as @code{const}. For ISO C such a type qualifier has no effect,
+since the value returned by a function is not an lvalue.
+For C++, the warning is only emitted for scalar types or @code{void}.
+ISO C prohibits qualified @code{void} return types on function
+definitions, so such return types always receive a warning
+even without this option.
+
+This warning is also enabled by @option{-Wextra}.
+
@item -Wmain
@opindex Wmain
Warn if the type of @samp{main} is suspicious. @samp{main} should be a
without a value), and about a @code{return} statement with a
expression in a function whose return-type is @code{void}.
-Also warn if the return type of a function has a type qualifier
-such as @code{const}. For ISO C such a type qualifier has no effect,
-since the value returned by a function is not an lvalue.
-For C++, the warning is only emitted for scalar types or @code{void}.
-ISO C prohibits qualified @code{void} return types on function
-definitions, so such return types always receive a warning
-even without this option.
-
For C++, a function without return type always produces a diagnostic
message, even when @option{-Wno-return-type} is specified. The only
exceptions are @samp{main} and functions defined in system headers.
Does not warn about incomplete types.
@item -Wstrict-overflow
-@item -Wstrict-overflow=@var{n}
+@itemx -Wstrict-overflow=@var{n}
@opindex Wstrict-overflow
This option is only active when @option{-fstrict-overflow} is active.
It warns about cases where the compiler optimizes based on the
compilation time.
@option{-O} turns on the following optimization flags:
-@gccoptlist{-fdefer-pop @gol
+@gccoptlist{
+-fauto-inc-dec @gol
+-fcprop-registers @gol
+-fdce @gol
+-fdefer-pop @gol
-fdelayed-branch @gol
+-fdse @gol
-fguess-branch-probability @gol
--fcprop-registers @gol
--fif-conversion @gol
-fif-conversion2 @gol
+-fif-conversion @gol
+-finline-small-functions @gol
+-fipa-pure-const @gol
+-fipa-reference @gol
+-fmerge-constants
-fsplit-wide-types @gol
-ftree-ccp @gol
+-ftree-ch @gol
+-ftree-copyrename @gol
-ftree-dce @gol
-ftree-dominator-opts @gol
-ftree-dse @gol
--ftree-ter @gol
--ftree-sra @gol
--ftree-copyrename @gol
-ftree-fre @gol
--ftree-ch @gol
--funit-at-a-time @gol
--finline-small-functions @gol
--fmerge-constants}
+-ftree-sra @gol
+-ftree-ter @gol
+-funit-at-a-time}
@option{-O} also turns on @option{-fomit-frame-pointer} on machines
where doing so does not interfere with debugging.
@option{-O2} turns on all optimization flags specified by @option{-O}. It
also turns on the following optimization flags:
@gccoptlist{-fthread-jumps @gol
+-falign-functions -falign-jumps @gol
+-falign-loops -falign-labels @gol
+-fcaller-saves @gol
-fcrossjumping @gol
--foptimize-sibling-calls @gol
-fcse-follow-jumps -fcse-skip-blocks @gol
--fgcse -fgcse-lm @gol
+-fdelete-null-pointer-checks @gol
-fexpensive-optimizations @gol
--frerun-cse-after-loop @gol
--fcaller-saves @gol
+-fgcse -fgcse-lm @gol
+-foptimize-sibling-calls @gol
-fpeephole2 @gol
--fschedule-insns -fschedule-insns2 @gol
--fsched-interblock -fsched-spec @gol
-fregmove @gol
--fstrict-aliasing -fstrict-overflow @gol
--fdelete-null-pointer-checks @gol
-freorder-blocks -freorder-functions @gol
--falign-functions -falign-jumps @gol
--falign-loops -falign-labels @gol
--ftree-vrp @gol
--ftree-pre}
+-frerun-cse-after-loop @gol
+-fsched-interblock -fsched-spec @gol
+-fschedule-insns -fschedule-insns2 @gol
+-fstrict-aliasing -fstrict-overflow @gol
+-ftree-pre @gol
+-ftree-vrp}
Please note the warning under @option{-fgcse} about
invoking @option{-O2} on programs that use computed gotos.
Disabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
-@item -fforce-addr
-@opindex fforce-addr
-Force memory address constants to be copied into registers before
-doing arithmetic on them.
-
@item -fforward-propagate
@opindex fforward-propagate
Perform a forward propagation pass on RTL. The pass tries to combine two
optimization is turned on, use the @option{-fno-keep-static-consts} option.
@item -fmerge-constants
+@opindex fmerge-constants
Attempt to merge identical constants (string constants and floating point
constants) across compilation units.
Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
@item -fmerge-all-constants
+@opindex fmerge-all-constants
Attempt to merge identical constants and identical variables.
This option implies @option{-fmerge-constants}. In addition to
The default is @option{-fzero-initialized-in-bss}.
-@item -fbounds-check
-@opindex fbounds-check
-For front-ends that support it, generate additional code to check that
-indices used to access arrays are within the declared range. This is
-currently only supported by the Java and Fortran front-ends, where
-this option defaults to true and false respectively.
-
@item -fmudflap -fmudflapth -fmudflapir
@opindex fmudflap
@opindex fmudflapth
@item -fcse-follow-jumps
@opindex fcse-follow-jumps
-In common subexpression elimination, scan through jump instructions
+In common subexpression elimination (CSE), scan through jump instructions
when the target of the jump is not reached by any other path. For
example, when CSE encounters an @code{if} statement with an
@code{else} clause, CSE will follow the jump when the condition
if it finds this kind of loop.
@item -fcrossjumping
-@opindex crossjumping
+@opindex fcrossjumping
Perform cross-jumping transformation. This transformation unifies equivalent code and save code size. The
resulting code may or may not perform better than without cross-jumping.
Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+@item -fauto-inc-dec
+@opindex fauto-inc-dec
+Combine increments or decrements of addresses with memory accesses.
+This pass is always skipped on architectures that do not have
+instructions to support this. Enabled by default at @option{-O} and
+higher on architectures that support this.
+
+@item -fdce
+@opindex fdce
+Perform dead code elimination (DCE) on RTL.
+Enabled by default at @option{-O} and higher.
+
+@item -fdse
+@opindex fdse
+Perform dead store elimination (DSE) on RTL.
+Enabled by default at @option{-O} and higher.
+
@item -fif-conversion
-@opindex if-conversion
+@opindex fif-conversion
Attempt to transform conditional jumps into branch-less equivalents. This
include use of conditional moves, min, max, set flags and abs instructions, and
some tricks doable by standard arithmetics. The use of conditional execution
Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
@item -fif-conversion2
-@opindex if-conversion2
+@opindex fif-conversion2
Use conditional execution (where available) to transform conditional jumps into
branch-less equivalents.
sense when scheduling before register allocation, i.e.@: with
@option{-fschedule-insns} or at @option{-O2} or higher.
-@item -fsched-stalled-insns=@var{n}
+@item -fsched-stalled-insns
+@itemx -fsched-stalled-insns=@var{n}
@opindex fsched-stalled-insns
Define how many insns (if any) can be moved prematurely from the queue
of stalled insns into the ready list, during the second scheduling pass.
-
-@item -fsched-stalled-insns-dep=@var{n}
+@option{-fno-sched-stalled-insns} means that no insns will be moved
+prematurely, @option{-fsched-stalled-insns=0} means there is no limit
+on how many queued insns can be moved prematurely.
+@option{-fsched-stalled-insns} without a value is equivalent to
+@option{-fsched-stalled-insns=1}.
+
+@item -fsched-stalled-insns-dep
+@itemx -fsched-stalled-insns-dep=@var{n}
@opindex fsched-stalled-insns-dep
Define how many insn groups (cycles) will be examined for a dependency
on a stalled insn that is candidate for premature removal from the queue
-of stalled insns. Has an effect only during the second scheduling pass,
-and only if @option{-fsched-stalled-insns} is used and its value is not zero.
+of stalled insns. This has an effect only during the second scheduling pass,
+and only if @option{-fsched-stalled-insns} is used.
+@option{-fno-sched-stalled-insns-dep} is equivalent to
+@option{-fsched-stalled-insns-dep=0}.
+@option{-fsched-stalled-insns-dep} without a value is equivalent to
+@option{-fsched-stalled-insns-dep=1}.
@item -fsched2-use-superblocks
@opindex fsched2-use-superblocks
@item -fsee
@opindex fsee
-Eliminates redundant extension instructions and move the non redundant
-ones to optimal placement using LCM.
+Eliminate redundant sign extension instructions and move the non-redundant
+ones to optimal placement using lazy code motion (LCM).
@item -freschedule-modulo-scheduled-loops
-@opindex fscheduling-in-modulo-scheduled-loops
+@opindex freschedule-modulo-scheduled-loops
The modulo scheduling comes before the traditional scheduling, if a loop
was modulo scheduled we may want to prevent the later scheduling passes
from changing its schedule, we use this option to control that.
Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
@item -ftree-reassoc
-Perform Reassociation on trees This flag is enabled by default
+@opindex ftree-reassoc
+Perform reassociation on trees. This flag is enabled by default
at @option{-O} and higher.
@item -ftree-pre
-Perform Partial Redundancy Elimination (PRE) on trees. This flag is
+@opindex ftree-pre
+Perform partial redundancy elimination (PRE) on trees. This flag is
enabled by default at @option{-O2} and @option{-O3}.
@item -ftree-fre
-Perform Full Redundancy Elimination (FRE) on trees. The difference
+@opindex ftree-fre
+Perform full redundancy elimination (FRE) on trees. The difference
between FRE and PRE is that FRE only considers expressions
that are computed on all paths leading to the redundant computation.
This analysis is faster than PRE, though it exposes fewer redundancies.
This flag is enabled by default at @option{-O} and higher.
@item -ftree-copy-prop
+@opindex ftree-copy-prop
Perform copy propagation on trees. This pass eliminates unnecessary
copy operations. This flag is enabled by default at @option{-O} and
higher.
-@item -ftree-store-copy-prop
-Perform copy propagation of memory loads and stores. This pass
-eliminates unnecessary copy operations in memory references
-(structures, global variables, arrays, etc). This flag is enabled by
-default at @option{-O2} and higher.
-
@item -ftree-salias
+@opindex ftree-salias
Perform structural alias analysis on trees. This flag
is enabled by default at @option{-O} and higher.
+@item -fipa-pure-const
+@opindex fipa-pure-const
+Discover which functions are pure or constant.
+Enabled by default at @option{-O} and higher.
+
+@item -fipa-reference
+@opindex fipa-reference
+Discover which static variables do not escape cannot escape the
+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). Require @option{-fipa-type-escape}
+to provide the safety of this transformation. It works only in whole program
+mode, so it requires @option{-fwhole-program} and @option{-combine} to be
+enabled. Structures considered @samp{cold} by this transformation are not
+affected (see @option{--param struct-reorg-cold-struct-ratio=@var{value}}).
+
+With this flag, the program debug info reflects a new structure layout.
+
@item -fipa-pta
+@opindex fipa-pta
Perform interprocedural pointer analysis.
+@item -fipa-cp
+@opindex fipa-cp
+Perform interprocedural constant propagation.
+This optimization analyzes the program to determine when values passed
+to functions are constants and then optimizes accordingly.
+This optimization can substantially increase performance
+if the application has constants passed to functions, but
+because this optimization can create multiple copies of functions,
+it may significantly increase code size.
+
+@item -fipa-matrix-reorg
+@opindex fipa-matrix-reorg
+Perform matrix flattening and transposing.
+Matrix flattening tries to replace a m-dimensional matrix
+with its equivalent n-dimensional matrix, where n < m.
+This reduces the level of indirection needed for accessing the elements
+of the matrix. The second optimization is matrix transposing that
+attemps to change the order of the matrix's dimensions in order to
+improve cache locality.
+Both optimizations need fwhole-program flag.
+Transposing is enabled only if profiling information is avaliable.
+
+
@item -ftree-sink
+@opindex ftree-sink
Perform forward store motion on trees. This flag is
enabled by default at @option{-O} and higher.
@item -ftree-ccp
+@opindex ftree-ccp
Perform sparse conditional constant propagation (CCP) on trees. This
pass only operates on local scalar variables and is enabled by default
at @option{-O} and higher.
@item -ftree-store-ccp
+@opindex ftree-store-ccp
Perform sparse conditional constant propagation (CCP) on trees. This
pass operates on both local scalar variables and memory stores and
loads (global variables, structures, arrays, etc). This flag is
enabled by default at @option{-O2} and higher.
@item -ftree-dce
+@opindex ftree-dce
Perform dead code elimination (DCE) on trees. This flag is enabled by
default at @option{-O} and higher.
@item -ftree-dominator-opts
+@opindex ftree-dominator-opts
Perform a variety of simple scalar cleanups (constant/copy
propagation, redundancy elimination, range propagation and expression
simplification) based on a dominator tree traversal. This also
flag is enabled by default at @option{-O} and higher.
@item -ftree-ch
+@opindex ftree-ch
Perform loop header copying on trees. This is beneficial since it increases
effectiveness of code motion optimizations. It also saves one jump. This flag
is enabled by default at @option{-O} and higher. It is not enabled
for @option{-Os}, since it usually increases code size.
@item -ftree-loop-optimize
+@opindex ftree-loop-optimize
Perform loop optimizations on trees. This flag is enabled by default
at @option{-O} and higher.
@item -ftree-loop-linear
+@opindex ftree-loop-linear
Perform linear loop transformations on tree. This flag can improve cache
performance and allow further loop optimizations to take place.
@item -fcheck-data-deps
+@opindex fcheck-data-deps
Compare the results of several data dependence analyzers. This option
is used for debugging the data dependence analyzers.
@item -ftree-loop-im
+@opindex ftree-loop-im
Perform loop invariant motion on trees. This pass moves only invariants that
would be hard to handle at RTL level (function calls, operations that expand to
nontrivial sequences of insns). With @option{-funswitch-loops} it also moves
store motion.
@item -ftree-loop-ivcanon
+@opindex ftree-loop-ivcanon
Create a canonical counter for number of iterations in the loop for that
determining number of iterations requires complicated analysis. Later
optimizations then may determine the number easily. Useful especially
in connection with unrolling.
@item -fivopts
+@opindex fivopts
Perform induction variable optimizations (strength reduction, induction
variable merging and induction variable elimination) on trees.
@item -ftree-parallelize-loops=n
-@opindex ftree-parallelize-loops=n
+@opindex ftree-parallelize-loops
Parallelize loops, i.e., split their iteration space to run in n threads.
This is only possible for loops whose iterations are independent
and can be arbitrarily reordered. The optimization is only
profitable on multiprocessor machines, for loops that are CPU-intensive,
-rather than constrained e.g. by memory bandwidth.
+rather than constrained e.g. by memory bandwidth. This option
+implies @option{-pthread}, and thus is only supported on targets
+that have support for @option{-pthread}.
@item -ftree-sra
+@opindex ftree-sra
Perform scalar replacement of aggregates. This pass replaces structure
references with scalars to prevent committing structures to memory too
early. This flag is enabled by default at @option{-O} and higher.
@item -ftree-copyrename
+@opindex ftree-copyrename
Perform copy renaming on trees. This pass attempts to rename compiler
temporaries to other variables at copy locations, usually resulting in
variable names which more closely resemble the original variables. This flag
is enabled by default at @option{-O} and higher.
@item -ftree-ter
+@opindex ftree-ter
Perform temporary expression replacement during the SSA->normal phase. Single
use/single def temporaries are replaced at their use location with their
defining expression. This results in non-GIMPLE code, but gives the expanders
enabled by default at @option{-O} and higher.
@item -ftree-vectorize
+@opindex ftree-vectorize
Perform loop vectorization on trees.
@item -ftree-vect-loop-version
except at level @option{-Os} where it is disabled.
@item -fvect-cost-model
+@opindex fvect-cost-model
Enable cost model for vectorization.
@item -ftree-vrp
+@opindex ftree-vrp
Perform Value Range Propagation on trees. This is similar to the
constant propagation pass, but instead of values, ranges of values are
propagated. This allows the optimizers to remove unnecessary range
Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
@item -fno-toplevel-reorder
+@opindex fno-toplevel-reorder
Do not reorder top-level functions, variables, and @code{asm}
statements. Output them in the same order that they appear in the
input file. When this option is used, unreferenced static variables
This option is not supported for Fortran programs.
-@item -fno-cprop-registers
-@opindex fno-cprop-registers
+@item -fcprop-registers
+@opindex fcprop-registers
After register allocation and post-register allocation instruction splitting,
we perform a copy-propagation pass to try to reduce scheduling dependencies
and occasionally eliminate the copy.
-Disabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
+Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
@item -fprofile-generate
@opindex fprofile-generate
@item -ffast-math
@opindex ffast-math
-Sets @option{-fno-math-errno}, @option{-funsafe-math-optimizations}, @*
-@option{-fno-trapping-math}, @option{-ffinite-math-only},
-@option{-fno-rounding-math}, @option{-fno-signaling-nans},
-@option{-fno-signed-zeros} and @option{fcx-limited-range}.
+Sets @option{-fno-math-errno}, @option{-funsafe-math-optimizations},
+@option{-ffinite-math-only}, @option{-fno-rounding-math},
+@option{-fno-signaling-nans} and @option{-fcx-limited-range}.
This option causes the preprocessor macro @code{__FAST_MATH__} to be defined.
an exact implementation of IEEE or ISO rules/specifications for
math functions. It may, however, yield faster code for programs
that do not require the guarantees of these specifications.
-Enables @option{-freciprocal-math} and @option{-fassociative-math}.
+Enables @option{-fno-signed-zeros}, @option{-fno-trapping-math},
+@option{-fassociative-math} and @option{-freciprocal-math}.
The default is @option{-fno-unsafe-math-optimizations}.
@item -fassociative-math
-@opindex -fassociative-math
+@opindex fassociative-math
Allow re-association of operands in series of floating-point operations.
This violates the ISO C and C++ language standard by possibly changing
thus cannot be used on a code which relies on rounding behavior like
@code{(x + 2**52) - 2**52)}. May also reorder floating-point comparisons
and thus may not be used when ordered comparisons are required.
-This flag doesn't make much sense without @option{-fno-signed-zeros}
-or @option{-fno-trapping-math} or with @option{-frounding-math}.
+This option requires that both @option{-fno-signed-zeros} and
+@option{-fno-trapping-math} be in effect. Moreover, it doesn't make
+much sense with @option{-frounding-math}.
The default is @option{-fno-associative-math}.
@item -freciprocal-math
-@opindex -freciprocal-math
+@opindex freciprocal-math
Allow the reciprocal of a value to be used instead of dividing by
the value if this enables optimizations. For example @code{x / y}
@opindex fno-trapping-math
Compile code assuming that floating-point operations cannot generate
user-visible traps. These traps include division by zero, overflow,
-underflow, inexact result and invalid operation. This option implies
-@option{-fno-signaling-nans}. Setting this option may allow faster
-code if one relies on ``non-stop'' IEEE arithmetic, for example.
+underflow, inexact result and invalid operation. This option requires
+that @option{-fno-signaling-nans} be in effect. Setting this option may
+allow faster code if one relies on ``non-stop'' IEEE arithmetic, for example.
This option should never be turned on by any @option{-O} option since
it can result in incorrect output for programs which depend on
implicitly converting it to double precision constant.
@item -fcx-limited-range
-@itemx -fno-cx-limited-range
@opindex fcx-limited-range
-@opindex fno-cx-limited-range
When enabled, this option states that a range reduction step is not
needed when performing complex division. The default is
@option{-fno-cx-limited-range}, but is enabled by @option{-ffast-math}.
branch target registers in within any basic block.
@item -fstack-protector
+@opindex fstack-protector
Emit extra code to check for buffer overflows, such as stack smashing
attacks. This is done by adding a guard variable to functions with
vulnerable objects. This includes functions that call alloca, and
If a guard check fails, an error message is printed and the program exits.
@item -fstack-protector-all
+@opindex fstack-protector-all
Like @option{-fstack-protector} except that all functions are protected.
@item -fsection-anchors
structure exceeds this parameter, then block copies are not used. The
default is 75.
+@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 max-crossjump-edges
The maximum number of incoming edges to consider for crossjumping.
The algorithm used by @option{-fcrossjumping} is @math{O(N^2)} in
taken into account. For function not declared inline, recursive inlining
happens only when @option{-finline-functions} (included in @option{-O3}) is
enabled and @option{--param max-inline-recursive-depth-auto} is used. The
-default value is 450.
+default value is 8.
@item min-inline-recursive-probability
Recursive inlining is profitable only for function having deep recursion
bugs in the canonical type system are causing compilation failures,
set this value to 0 to disable canonical types.
+@item max-partial-antic-length
+Maximum length of the partial antic set computed during the tree
+partial redundancy elimination optimization (@option{-ftree-pre}) when
+optimizing at @option{-O3} and above. For some sorts of source code
+the enhanced partial redundancy elimination optimization can run away,
+consuming all of the memory available on the host machine. This
+parameter sets a limit on the length of the sets that are computed,
+which prevents the runaway behaviour. Setting a value of 0 for
+this paramter will allow an unlimited set length.
+
+@item sccvn-max-scc-size
+Maximum size of a strongly connected component (SCC) during SCCVN
+processing. If this limit is hit, SCCVN processing for the whole
+function will not be done and optimizations depending on it will
+be disabled. The default maximum SCC size is 10000.
+
@end table
@end table
Specifies that the program will be run on the simulator. This causes
the simulator BSP provided by libgloss to be linked in. This option
has effect only for @samp{bfin-elf} toolchain.
+Certain other options, such as @option{-mid-shared-library} and
+@option{-mfdpic}, imply @option{-msim}.
@item -momit-leaf-frame-pointer
@opindex momit-leaf-frame-pointer
Generate code that supports shared libraries via the library ID method.
This allows for execute in place and shared libraries in an environment
without virtual memory management. This option implies @option{-fPIC}.
+With a @samp{bfin-elf} target, this option implies @option{-msim}.
@item -mno-id-shared-library
@opindex mno-id-shared-library
assumes GOT entries and small data are within a 12-bit range from the
GOT base address; with @option{-fPIC} or @option{-fPIE}, GOT offsets
are computed with 32 bits.
+With a @samp{bfin-elf} target, this option implies @option{-msim}.
@item -minline-plt
@opindex minline-plt
@item -mrecip
@opindex mrecip
This option will enable GCC to use RCPSS and RSQRTSS instructions (and their
-vectorized variants RCPPS and RSQRTPS) instead of DIVSS and SQRTSS (and their
-vectorized variants). These instructions will be generated only when
-@option{-funsafe-math-optimizations} is enabled.
+vectorized variants RCPPS and RSQRTPS) with an additional Newton-Rhapson step
+to increase precision instead of DIVSS and SQRTSS (and their vectorized
+variants) for single precision floating point arguments. These instructions
+are generated only when @option{-funsafe-math-optimizations} is enabled
+together with @option{-finite-math-only} and @option{-fno-trapping-math}.
+Note that while the throughput of the sequence is higher than the throughput
+of the non-reciprocal instruction, the precision of the sequence can be
+decreased by up to 2 ulp (i.e. the inverse of 1.0 equals 0.99999994).
@item -mveclibabi=@var{type}
@opindex mveclibabi
@itemx -mno-cmpb
@itemx -mmfpgpr
@itemx -mno-mfpgpr
-@itemx -mdfp
-@itemx -mno-dfp
+@itemx -mhard-dfp
+@itemx -mno-hard-dfp
@opindex mpower
@opindex mno-power
@opindex mpower2
@opindex mno-cmpb
@opindex mmfpgpr
@opindex mno-mfpgpr
-@opindex mdfp
-@opindex mno-dfp
+@opindex mhard-dfp
+@opindex mno-hard-dfp
GCC supports two related instruction set architectures for the
RS/6000 and PowerPC@. The @dfn{POWER} instruction set are those
instructions supported by the @samp{rios} chip set used in the original
general purpose register instructions implemented on the POWER6X
processor and other processors that support the extended PowerPC V2.05
architecture.
-The @option{-mdfp} option allows GCC to generate the decimal floating
+The @option{-mhard-dfp} option allows GCC to generate the decimal floating
point instructions implemented on some POWER processors.
The @option{-mpowerpc64} option allows GCC to generate the additional
Not all targets provide complete support for this switch.
@item -ftls-model=@var{model}
+@opindex ftls-model
Alter the thread-local storage model to be used (@pxref{Thread-Local}).
The @var{model} argument should be one of @code{global-dynamic},
@code{local-dynamic}, @code{initial-exec} or @code{local-exec}.
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