rtlanal.c (subreg_offset_representable_p): Check HARD_REGNO_MODE_OK.

[gcc.git] / gcc / common.opt

; Options for the language- and target-independent parts of the compiler.

; Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008
; Free Software Foundation, Inc.
;
; This file is part of GCC.
;
; GCC is free software; you can redistribute it and/or modify it under
; the terms of the GNU General Public License as published by the Free
; Software Foundation; either version 3, or (at your option) any later
; version.
;
; GCC is distributed in the hope that it will be useful, but WITHOUT ANY
; WARRANTY; without even the implied warranty of MERCHANTABILITY or
; FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
; for more details.
;
; You should have received a copy of the GNU General Public License
; along with GCC; see the file COPYING3.  If not see
; <http://www.gnu.org/licenses/>.

; See the GCC internals manual (options.texi) for a description of this file's format.

; Please try to keep this file in ASCII collating order.

-help
Common
Display this information

-help=
Common Report Joined
--help=<class>	Display descriptions of a specific class of options.  <class> is one or more of optimizers, target, warnings, undocumented, params

-target-help
Common
Alias for --help=target

;; The following three entries are to work around the gcc driver
;; program's insatiable desire to turn options starting with a
;; double dash (--) into options starting with a dash f (-f).
fhelp
Common

fhelp=
Common Joined

ftarget-help
Common

-param
Common Separate
--param <param>=<value>	Set parameter <param> to value.  See below for a complete list of parameters

-version
Common

G
Common Joined Separate UInteger
-G<number>	Put global and static data smaller than <number> bytes into a special section (on some targets)

O
Common JoinedOrMissing Optimization
-O<number>	Set optimization level to <number>

Os
Common Optimization
Optimize for space rather than speed

W
Common RejectNegative
This switch is deprecated; use -Wextra instead

Waggregate-return
Common Var(warn_aggregate_return) Warning
Warn about returning structures, unions or arrays

Warray-bounds
Common Var(warn_array_bounds) Warning
Warn if an array is accessed out of bounds

Wattributes
Common Var(warn_attributes) Init(1) Warning
Warn about inappropriate attribute usage

Wcast-align
Common Var(warn_cast_align) Warning
Warn about pointer casts which increase alignment

Wdeprecated-declarations
Common Var(warn_deprecated_decl) Init(1) Warning
Warn about uses of __attribute__((deprecated)) declarations

Wdisabled-optimization
Common Var(warn_disabled_optimization) Warning
Warn when an optimization pass is disabled

Wdisallowed-function-list=
Common RejectNegative Joined Warning
Warn on calls to these functions

Werror
Common Var(warnings_are_errors)
Treat all warnings as errors

Werror=
Common Joined
Treat specified warning as error

Wextra
Common Warning
Print extra (possibly unwanted) warnings

Wfatal-errors
Common Var(flag_fatal_errors)
Exit on the first error occurred

Wframe-larger-than=
Common RejectNegative Joined UInteger
-Wframe-larger-than=<number> Warn if a function's stack frame requires more than <number> bytes

Winline
Common Var(warn_inline) Warning
Warn when an inlined function cannot be inlined

Wlarger-than-
Common RejectNegative Joined UInteger Warning

Wlarger-than=
Common RejectNegative Joined UInteger Warning
-Wlarger-than=<number>	Warn if an object is larger than <number> bytes

Wlogical-op
Common Warning Var(warn_logical_op)
Warn when a logical operator is suspicously always evaluating to true or false

Wunsafe-loop-optimizations
Common Var(warn_unsafe_loop_optimizations) Warning
Warn if the loop cannot be optimized due to nontrivial assumptions.

Wmissing-noreturn
Common Var(warn_missing_noreturn) Warning
Warn about functions which might be candidates for __attribute__((noreturn))

Wmudflap
Common Var(warn_mudflap) Init(1) Warning
Warn about constructs not instrumented by -fmudflap

Woverflow
Common Var(warn_overflow) Init(1) Warning
Warn about overflow in arithmetic expressions

Wpacked
Common Var(warn_packed) Warning
Warn when the packed attribute has no effect on struct layout

Wpadded
Common Var(warn_padded) Warning
Warn when padding is required to align structure members

Wshadow
Common Var(warn_shadow) Warning
Warn when one local variable shadows another

Wstack-protector
Common Var(warn_stack_protect) Warning
Warn when not issuing stack smashing protection for some reason

Wstrict-aliasing
Common Warning
Warn about code which might break strict aliasing rules

Wstrict-aliasing=
Common Joined UInteger Var(warn_strict_aliasing) Init(-1) Warning
Warn about code which might break strict aliasing rules

Wstrict-overflow
Common Warning
Warn about optimizations that assume that signed overflow is undefined

Wstrict-overflow=
Common Joined UInteger Var(warn_strict_overflow) Init(-1) Warning
Warn about optimizations that assume that signed overflow is undefined

Wswitch
Common Var(warn_switch) Warning
Warn about enumerated switches, with no default, missing a case

Wswitch-default
Common Var(warn_switch_default) Warning
Warn about enumerated switches missing a \"default:\" statement

Wswitch-enum
Common Var(warn_switch_enum) Warning
Warn about all enumerated switches missing a specific case

Wsystem-headers
Common Var(warn_system_headers) Warning
Do not suppress warnings from system headers

Wtype-limits
Common Var(warn_type_limits) Init(-1) Warning
Warn if a comparison is always true or always false due to the limited range of the data type

Wuninitialized
Common Var(warn_uninitialized) Warning
Warn about uninitialized automatic variables

Wunreachable-code
Common Var(warn_notreached) Warning
Warn about code that will never be executed

Wunused
Common Var(warn_unused) Init(0) Warning
Enable all -Wunused- warnings

Wunused-function
Common Var(warn_unused_function) Init(-1) Warning
Warn when a function is unused

Wunused-label
Common Var(warn_unused_label) Init(-1) Warning
Warn when a label is unused

Wunused-parameter
Common Var(warn_unused_parameter) Init(-1) Warning
Warn when a function parameter is unused

Wunused-value
Common Var(warn_unused_value) Init(-1) Warning
Warn when an expression value is unused

Wunused-variable
Common Var(warn_unused_variable) Init(-1) Warning
Warn when a variable is unused

Wcoverage-mismatch
Common RejectNegative Var(warn_coverage_mismatch) Warning
Warn instead of error in case profiles in -fprofile-use do not match

aux-info
Common Separate
-aux-info <file>	Emit declaration information into <file>

aux-info=
Common Joined

auxbase
Common Separate

auxbase-strip
Common Separate

d
Common Joined
-d<letters>	Enable dumps from specific passes of the compiler

dumpbase
Common Separate
-dumpbase <file>	Set the file basename to be used for dumps

; The version of the C++ ABI in use.  The following values are allowed:
;
; 0: The version of the ABI believed most conformant with the C++ ABI
;    specification.  This ABI may change as bugs are discovered and fixed.
;    Therefore, 0 will not necessarily indicate the same ABI in different
;    versions of G++.
;
; 1: The version of the ABI first used in G++ 3.2.
;
; 2: The version of the ABI first used in G++ 3.4.
;
; Additional positive integers will be assigned as new versions of
; the ABI become the default version of the ABI.
fabi-version=
Common Joined UInteger Var(flag_abi_version) Init(2)

falign-functions
Common Report Var(align_functions,0) Optimization UInteger
Align the start of functions

falign-functions=
Common RejectNegative Joined UInteger

falign-jumps
Common Report Var(align_jumps,0) Optimization UInteger
Align labels which are only reached by jumping

falign-jumps=
Common RejectNegative Joined UInteger

falign-labels
Common Report Var(align_labels,0) Optimization UInteger
Align all labels

falign-labels=
Common RejectNegative Joined UInteger

falign-loops
Common Report Var(align_loops) Optimization UInteger
Align the start of loops

falign-loops=
Common RejectNegative Joined UInteger

; This flag is only tested if alias checking is enabled.
; 0 if pointer arguments may alias each other.  True in C.
; 1 if pointer arguments may not alias each other but may alias
;   global variables.
; 2 if pointer arguments may not alias each other and may not
;   alias global variables.
; 3 if pointer arguments may not alias anything.  True in Fortran.
;   Set by the front end.
fargument-alias
Common Report Var(flag_argument_noalias,0) Optimization
Specify that arguments may alias each other and globals

fargument-noalias
Common Report Var(flag_argument_noalias,1) VarExists Optimization
Assume arguments may alias globals but not each other

fargument-noalias-global
Common Report Var(flag_argument_noalias,2) VarExists Optimization
Assume arguments alias neither each other nor globals

fargument-noalias-anything
Common Report Var(flag_argument_noalias,3) VarExists Optimization
Assume arguments alias no other storage

fasynchronous-unwind-tables
Common Report Var(flag_asynchronous_unwind_tables) Optimization
Generate unwind tables that are exact at each instruction boundary

fauto-inc-dec
Common Report Var(flag_auto_inc_dec) Init(1)
Generate auto-inc/dec instructions

; -fcheck-bounds causes gcc to generate array bounds checks.
; For C, C++ and ObjC: defaults off.
; For Java: defaults to on.
; For Fortran: defaults to off.
fbounds-check
Common Report Var(flag_bounds_check)
Generate code to check bounds before indexing arrays

fbranch-count-reg
Common Report Var(flag_branch_on_count_reg) Init(1) Optimization
Replace add, compare, branch with branch on count register

fbranch-probabilities
Common Report Var(flag_branch_probabilities) Optimization
Use profiling information for branch probabilities

fbranch-target-load-optimize
Common Report Var(flag_branch_target_load_optimize) Optimization
Perform branch target load optimization before prologue / epilogue threading

fbranch-target-load-optimize2
Common Report Var(flag_branch_target_load_optimize2) Optimization
Perform branch target load optimization after prologue / epilogue threading

fbtr-bb-exclusive
Common Report Var(flag_btr_bb_exclusive) Optimization
Restrict target load migration not to re-use registers in any basic block

fcall-saved-
Common Joined RejectNegative
-fcall-saved-<register>	Mark <register> as being preserved across functions

fcall-used-
Common Joined RejectNegative
-fcall-used-<register>	Mark <register> as being corrupted by function calls

; Nonzero for -fcaller-saves: allocate values in regs that need to
; be saved across function calls, if that produces overall better code.
; Optional now, so people can test it.
fcaller-saves
Common Report Var(flag_caller_saves) Optimization
Save registers around function calls

fcheck-data-deps
Common Report Var(flag_check_data_deps)
Compare the results of several data dependence analyzers.

fcommon
Common Report Var(flag_no_common,0) Optimization
Do not put uninitialized globals in the common section

fcprop-registers
Common Report Var(flag_cprop_registers) Optimization
Perform a register copy-propagation optimization pass

fcrossjumping
Common Report Var(flag_crossjumping) Optimization
Perform cross-jumping optimization

fcse-follow-jumps
Common Report Var(flag_cse_follow_jumps) Optimization
When running CSE, follow jumps to their targets

fcse-skip-blocks
Common Report Var(flag_cse_skip_blocks) Optimization
When running CSE, follow conditional jumps

fcx-limited-range
Common Report Var(flag_cx_limited_range) Optimization
Omit range reduction step when performing complex division

fcx-fortran-rules
Common Report Var(flag_cx_fortran_rules) Optimization
Complex multiplication and division follow Fortran rules

fdata-sections
Common Report Var(flag_data_sections) Optimization
Place data items into their own section

fdbg-cnt-list
Common Report
List all available debugging counters with their limits and counts.

fdbg-cnt=
Common RejectNegative Joined
-fdbg-cnt=<counter>:<limit>[,<counter>:<limit>,...]    Set the debug counter limit.   

fdebug-prefix-map=
Common Joined RejectNegative
Map one directory name to another in debug information

; Nonzero for -fdefer-pop: don't pop args after each function call
; instead save them up to pop many calls' args with one insns.
fdefer-pop
Common Report Var(flag_defer_pop) Optimization
Defer popping functions args from stack until later

fdelayed-branch
Common Report Var(flag_delayed_branch) Optimization
Attempt to fill delay slots of branch instructions

fdelete-null-pointer-checks
Common Report Var(flag_delete_null_pointer_checks) Optimization
Delete useless null pointer checks

fdiagnostics-show-location=
Common Joined RejectNegative
-fdiagnostics-show-location=[once|every-line]	How often to emit source location at the beginning of line-wrapped diagnostics

fdiagnostics-show-option
Common
Amend appropriate diagnostic messages with the command line option that controls them

fdump-
Common Joined RejectNegative
-fdump-<type>	Dump various compiler internals to a file

fdump-noaddr
Common Report Var(flag_dump_noaddr)
Suppress output of addresses in debugging dumps

fdump-unnumbered
Common Report Var(flag_dump_unnumbered) VarExists
Suppress output of instruction numbers, line number notes and addresses in debugging dumps

fdwarf2-cfi-asm
Common Report Var(flag_dwarf2_cfi_asm) Init(HAVE_GAS_CFI_DIRECTIVE)
Enable CFI tables via GAS assembler directives.

fearly-inlining
Common Report Var(flag_early_inlining) Init(1) Optimization
Perform early inlining

feliminate-dwarf2-dups
Common Report Var(flag_eliminate_dwarf2_dups)
Perform DWARF2 duplicate elimination

feliminate-unused-debug-symbols
Common Report Var(flag_debug_only_used_symbols)
Perform unused type elimination in debug info

feliminate-unused-debug-types
Common Report Var(flag_eliminate_unused_debug_types) Init(1)
Perform unused type elimination in debug info

femit-class-debug-always
Common Report Var(flag_emit_class_debug_always) Init(0)
Do not suppress C++ class debug information.

fexceptions
Common Report Var(flag_exceptions) Optimization
Enable exception handling

fexpensive-optimizations
Common Report Var(flag_expensive_optimizations) Optimization
Perform a number of minor, expensive optimizations

ffast-math
Common

ffinite-math-only
Common Report Var(flag_finite_math_only) Optimization
Assume no NaNs or infinities are generated

ffixed-
Common Joined RejectNegative
-ffixed-<register>	Mark <register> as being unavailable to the compiler

ffloat-store
Common Report Var(flag_float_store) Optimization
Don't allocate floats and doubles in extended-precision registers

fforce-addr
Common
Does nothing.  Preserved for backward compatibility.

fforward-propagate
Common Report Var(flag_forward_propagate) Optimization
Perform a forward propagation pass on RTL

; Nonzero means don't put addresses of constant functions in registers.
; Used for compiling the Unix kernel, where strange substitutions are
; done on the assembly output.
ffunction-cse
Common Report Var(flag_no_function_cse,0)
Allow function addresses to be held in registers

ffunction-sections
Common Report Var(flag_function_sections)
Place each function into its own section

fgcse
Common Report Var(flag_gcse) Optimization
Perform global common subexpression elimination

fgcse-lm
Common Report Var(flag_gcse_lm) Init(1) Optimization
Perform enhanced load motion during global common subexpression elimination

fgcse-sm
Common Report Var(flag_gcse_sm) Init(0) Optimization
Perform store motion after global common subexpression elimination

fgcse-las
Common Report Var(flag_gcse_las) Init(0) Optimization
Perform redundant load after store elimination in global common subexpression
elimination

fgcse-after-reload
Common Report Var(flag_gcse_after_reload) Optimization
Perform global common subexpression elimination after register allocation
has finished

fguess-branch-probability
Common Report Var(flag_guess_branch_prob) Optimization
Enable guessing of branch probabilities

; Nonzero means ignore `#ident' directives.  0 means handle them.
; Generate position-independent code for executables if possible
; On SVR4 targets, it also controls whether or not to emit a
; string identifying the compiler.
fident
Common Report Var(flag_no_ident,0)
Process #ident directives

fif-conversion
Common Report Var(flag_if_conversion) Optimization
Perform conversion of conditional jumps to branchless equivalents

fif-conversion2
Common Report Var(flag_if_conversion2) Optimization
Perform conversion of conditional jumps to conditional execution

; -finhibit-size-directive inhibits output of .size for ELF.
; This is used only for compiling crtstuff.c,
; and it may be extended to other effects
; needed for crtstuff.c on other systems.
finhibit-size-directive
Common Report Var(flag_inhibit_size_directive)
Do not generate .size directives

findirect-inlining
Common Report Var(flag_indirect_inlining)
Perform indirect inlining

; Nonzero means that functions declared `inline' will be treated
; as `static'.  Prevents generation of zillions of copies of unused
; static inline functions; instead, `inlines' are written out
; only when actually used.  Used in conjunction with -g.  Also
; does the right thing with #pragma interface.
finline
Common Report Var(flag_no_inline,0) Init(0)
Pay attention to the \"inline\" keyword

finline-small-functions
Common Report Var(flag_inline_small_functions) Optimization
Integrate simple functions into their callers when code size is known to not growth

finline-functions
Common Report Var(flag_inline_functions) Optimization
Integrate simple functions into their callers

finline-functions-called-once
Common Report Var(flag_inline_functions_called_once) Init(1) Optimization
Integrate functions called once into their callers

finline-limit-
Common RejectNegative Joined UInteger

finline-limit=
Common RejectNegative Joined UInteger
-finline-limit=<number>	Limit the size of inlined functions to <number>

finstrument-functions
Common Report Var(flag_instrument_function_entry_exit)
Instrument function entry and exit with profiling calls

finstrument-functions-exclude-function-list=
Common RejectNegative Joined
-finstrument-functions-exclude-function-list=name,...  Do not instrument listed functions

finstrument-functions-exclude-file-list=
Common RejectNegative Joined
-finstrument-functions-exclude-file-list=filename,...  Do not instrument functions listed in files

fipa-cp
Common Report Var(flag_ipa_cp) Optimization
Perform Interprocedural constant propagation

fipa-pure-const
Common Report Var(flag_ipa_pure_const) Init(0) Optimization
Discover pure and const functions

fipa-pta
Common Report Var(flag_ipa_pta) Init(0) Optimization
Perform interprocedural points-to analysis

fipa-reference
Common Report Var(flag_ipa_reference) Init(0) Optimization
Discover readonly and non addressable static variables

fipa-type-escape
Common Report Var(flag_ipa_type_escape) Init(0) Optimization
Type based escape and alias analysis

fipa-matrix-reorg
Common Report Var(flag_ipa_matrix_reorg) Optimization
Perform matrix layout flattening and transposing based
on profiling information.

fipa-struct-reorg
Common Report Var(flag_ipa_struct_reorg)
Perform structure layout optimizations based
on profiling information.

fivopts
Common Report Var(flag_ivopts) Init(1) Optimization
Optimize induction variables on trees

fjump-tables
Common Var(flag_jump_tables) Init(1) Optimization
Use jump tables for sufficiently large switch statements

fkeep-inline-functions
Common Report Var(flag_keep_inline_functions)
Generate code for functions even if they are fully inlined

fkeep-static-consts
Common Report Var(flag_keep_static_consts) Init(1)
Emit static const variables even if they are not used

fleading-underscore
Common Report Var(flag_leading_underscore) Init(-1)
Give external symbols a leading underscore

floop-optimize
Common
Does nothing.  Preserved for backward compatibility.

fmath-errno
Common Report Var(flag_errno_math) Init(1) Optimization
Set errno after built-in math functions

fmem-report
Common Report Var(mem_report)
Report on permanent memory allocation

; This will attempt to merge constant section constants, if 1 only
; string constants and constants from constant pool, if 2 also constant
; variables.
fmerge-all-constants
Common Report Var(flag_merge_constants,2) Init(1) Optimization
Attempt to merge identical constants and constant variables

fmerge-constants
Common Report Var(flag_merge_constants,1) VarExists Optimization
Attempt to merge identical constants across compilation units

fmerge-debug-strings
Common Report Var(flag_merge_debug_strings) Init(1)
Attempt to merge identical debug strings across compilation units

fmessage-length=
Common RejectNegative Joined UInteger
-fmessage-length=<number>	Limit diagnostics to <number> characters per line.  0 suppresses line-wrapping

fmodulo-sched
Common Report Var(flag_modulo_sched) Optimization
Perform SMS based modulo scheduling before the first scheduling pass

fmodulo-sched-allow-regmoves
Common Report Var(flag_modulo_sched_allow_regmoves)
Perform SMS based modulo scheduling with register moves allowed

fmove-loop-invariants
Common Report Var(flag_move_loop_invariants) Init(1) Optimization
Move loop invariant computations out of loops

fmudflap
Common RejectNegative Report Var(flag_mudflap)
Add mudflap bounds-checking instrumentation for single-threaded program

fmudflapth
Common RejectNegative Report VarExists Var(flag_mudflap,2)
Add mudflap bounds-checking instrumentation for multi-threaded program

fmudflapir
Common RejectNegative Report Var(flag_mudflap_ignore_reads)
Ignore read operations when inserting mudflap instrumentation

fdce
Common Var(flag_dce) Init(1) Optimization
Use the RTL dead code elimination pass

fdse
Common Var(flag_dse) Init(1) Optimization
Use the RTL dead store elimination pass

freschedule-modulo-scheduled-loops
Common Report Var(flag_resched_modulo_sched) Optimization
Enable/Disable the traditional scheduling in loops that already passed modulo scheduling

fnon-call-exceptions
Common Report Var(flag_non_call_exceptions) Optimization
Support synchronous non-call exceptions

fomit-frame-pointer
Common Report Var(flag_omit_frame_pointer) Optimization
When possible do not generate stack frames

foptimize-register-move
Common Report Var(flag_regmove) Optimization
Do the full register move optimization pass

foptimize-sibling-calls
Common Report Var(flag_optimize_sibling_calls) Optimization
Optimize sibling and tail recursive calls

fpre-ipa-mem-report
Common Report Var(pre_ipa_mem_report)
Report on memory allocation before interprocedural optimization

fpost-ipa-mem-report
Common Report Var(post_ipa_mem_report)
Report on memory allocation before interprocedural optimization

fpack-struct
Common Report Var(flag_pack_struct) Optimization
Pack structure members together without holes

fpack-struct=
Common RejectNegative Joined UInteger Optimization
-fpack-struct=<number>	Set initial maximum structure member alignment

fpcc-struct-return
Common Report Var(flag_pcc_struct_return,1) VarExists
Return small aggregates in memory, not registers

fpeel-loops
Common Report Var(flag_peel_loops) Optimization
Perform loop peeling

fpeephole
Common Report Var(flag_no_peephole,0) Optimization
Enable machine specific peephole optimizations

fpeephole2
Common Report Var(flag_peephole2) Optimization
Enable an RTL peephole pass before sched2

fPIC
Common Report Var(flag_pic,2)
Generate position-independent code if possible (large mode)

fPIE
Common Report Var(flag_pie,2)
Generate position-independent code for executables if possible (large mode)

fpic
Common Report Var(flag_pic,1) VarExists
Generate position-independent code if possible (small mode)

fpie
Common Report Var(flag_pie,1) VarExists
Generate position-independent code for executables if possible (small mode)

fpredictive-commoning
Common Report Var(flag_predictive_commoning) Optimization
Run predictive commoning optimization.

fprefetch-loop-arrays
Common Report Var(flag_prefetch_loop_arrays) Optimization
Generate prefetch instructions, if available, for arrays in loops

fprofile
Common Report Var(profile_flag)
Enable basic program profiling code

fprofile-arcs
Common Report Var(profile_arc_flag)
Insert arc-based program profiling code

fprofile-dir=
Common Joined RejectNegative
Set the top-level directory for storing the profile data.
The default is 'pwd'.

fprofile-generate
Common
Enable common options for generating profile info for profile feedback directed optimizations

fprofile-generate=
Common Joined RejectNegative
Enable common options for generating profile info for profile feedback directed optimizations, and set -fprofile-dir=

fprofile-use
Common Var(flag_profile_use)
Enable common options for performing profile feedback directed optimizations

fprofile-use=
Common Joined RejectNegative
Enable common options for performing profile feedback directed optimizations, and set -fprofile-dir=

fprofile-values
Common Report Var(flag_profile_values)
Insert code to profile values of expressions

frandom-seed
Common

frandom-seed=
Common Joined RejectNegative
-frandom-seed=<string>	Make compile reproducible using <string>

; This switch causes the command line that was used to create an
; object file to be recorded into the object file.  The exact format
; of this recording is target and binary file format dependent.
; It is related to the -fverbose-asm switch, but that switch only
; records information in the assembler output file as comments, so
; they never reach the object file.
frecord-gcc-switches
Common Report Var(flag_record_gcc_switches)
Record gcc command line switches in the object file.

freg-struct-return
Common Report Var(flag_pcc_struct_return,0) VarExists Optimization
Return small aggregates in registers

fregmove
Common Report Var(flag_regmove) Optimization
Enables a register move optimization

frename-registers
Common Report Var(flag_rename_registers) Init(2) Optimization
Perform a register renaming optimization pass

freorder-blocks
Common Report Var(flag_reorder_blocks) Optimization
Reorder basic blocks to improve code placement

freorder-blocks-and-partition
Common Report Var(flag_reorder_blocks_and_partition) Optimization
Reorder basic blocks and partition into hot and cold sections

freorder-functions
Common Report Var(flag_reorder_functions) Optimization
Reorder functions to improve code placement

frerun-cse-after-loop
Common Report Var(flag_rerun_cse_after_loop) Init(2) Optimization
Add a common subexpression elimination pass after loop optimizations

frerun-loop-opt
Common
Does nothing.  Preserved for backward compatibility.

frounding-math
Common Report Var(flag_rounding_math) Optimization
Disable optimizations that assume default FP rounding behavior

fsched-interblock
Common Report Var(flag_schedule_interblock) Init(1) Optimization
Enable scheduling across basic blocks

fsched-spec
Common Report Var(flag_schedule_speculative) Init(1) Optimization
Allow speculative motion of non-loads

fsched-spec-load
Common Report Var(flag_schedule_speculative_load) Optimization
Allow speculative motion of some loads

fsched-spec-load-dangerous
Common Report Var(flag_schedule_speculative_load_dangerous) Optimization
Allow speculative motion of more loads

fsched-verbose=
Common RejectNegative Joined
-fsched-verbose=<number>	Set the verbosity level of the scheduler

fsched2-use-superblocks
Common Report Var(flag_sched2_use_superblocks) Optimization
If scheduling post reload, do superblock scheduling

fsched2-use-traces
Common Report Var(flag_sched2_use_traces) Optimization
If scheduling post reload, do trace scheduling

fschedule-insns
Common Report Var(flag_schedule_insns) Optimization
Reschedule instructions before register allocation

fschedule-insns2
Common Report Var(flag_schedule_insns_after_reload) Optimization
Reschedule instructions after register allocation

; sched_stalled_insns means that insns can be moved prematurely from the queue
; of stalled insns into the ready list.
fsched-stalled-insns
Common Report Var(flag_sched_stalled_insns) Optimization UInteger
Allow premature scheduling of queued insns

fsched-stalled-insns=
Common RejectNegative Joined UInteger
-fsched-stalled-insns=<number>	Set number of queued insns that can be prematurely scheduled

; sched_stalled_insns_dep controls how many recently scheduled cycles will
; be examined for a dependency on a stalled insn that is candidate for
; premature removal from the queue of stalled insns into the ready list (has
; an effect only if the flag 'sched_stalled_insns' is set).
fsched-stalled-insns-dep
Common Report Var(flag_sched_stalled_insns_dep,1) Init(1) Optimization UInteger
Set dependence distance checking in premature scheduling of queued insns

fsched-stalled-insns-dep=
Common RejectNegative Joined UInteger
-fsched-stalled-insns-dep=<number>	Set dependence distance checking in premature scheduling of queued insns

fsection-anchors
Common Report Var(flag_section_anchors) Optimization
Access data in the same section from shared anchor points

frtl-abstract-sequences
Common Report Var(flag_rtl_seqabstr) Optimization
Perform sequence abstraction optimization on RTL

fsee
Common Report Var(flag_see) Init(0)
Eliminate redundant sign extensions using LCM.

fshow-column
Common C ObjC C++ ObjC++ Report Var(flag_show_column) Init(0)
Show column numbers in diagnostics, when available.  Default off

fsignaling-nans
Common Report Var(flag_signaling_nans) Optimization
Disable optimizations observable by IEEE signaling NaNs

fsigned-zeros
Common Report Var(flag_signed_zeros) Init(1) Optimization
Disable floating point optimizations that ignore the IEEE signedness of zero

fsingle-precision-constant
Common Report Var(flag_single_precision_constant) Optimization
Convert floating point constants to single precision constants

fsplit-ivs-in-unroller
Common Report Var(flag_split_ivs_in_unroller) Init(1) Optimization
Split lifetimes of induction variables when loops are unrolled

fsplit-wide-types
Common Report Var(flag_split_wide_types) Optimization
Split wide types into independent registers

fvariable-expansion-in-unroller
Common Report Var(flag_variable_expansion_in_unroller) Optimization
Apply variable expansion when loops are unrolled

fstack-check=
Common Report RejectNegative Joined
-fstack-check=[no|generic|specific]	Insert stack checking code into the program

fstack-check
Common Report
Insert stack checking code into the program.  Same as -fstack-check=specific

fstack-limit
Common

fstack-limit-register=
Common RejectNegative Joined
-fstack-limit-register=<register>	Trap if the stack goes past <register>

fstack-limit-symbol=
Common RejectNegative Joined
-fstack-limit-symbol=<name>	Trap if the stack goes past symbol <name>

fstack-protector
Common Report Var(flag_stack_protect, 1)
Use propolice as a stack protection method

fstack-protector-all
Common Report RejectNegative Var(flag_stack_protect, 2) VarExists
Use a stack protection method for every function

fstrength-reduce
Common
Does nothing.  Preserved for backward compatibility.

; Nonzero if we should do (language-dependent) alias analysis.
; Typically, this analysis will assume that expressions of certain
; types do not alias expressions of certain other types.  Only used
; if alias analysis (in general) is enabled.
fstrict-aliasing
Common Report Var(flag_strict_aliasing) Optimization
Assume strict aliasing rules apply

fstrict-overflow
Common Report Var(flag_strict_overflow)
Treat signed overflow as undefined

fsyntax-only
Common Report Var(flag_syntax_only)
Check for syntax errors, then stop

ftest-coverage
Common Report Var(flag_test_coverage)
Create data files needed by \"gcov\"

fthread-jumps
Common Report Var(flag_thread_jumps) Optimization
Perform jump threading optimizations

ftime-report
Common Report Var(time_report)
Report the time taken by each compiler pass

ftls-model=
Common Joined RejectNegative
-ftls-model=[global-dynamic|local-dynamic|initial-exec|local-exec]	Set the default thread-local storage code generation model

ftoplevel-reorder
Common Report Var(flag_toplevel_reorder) Init(2) Optimization
Reorder top level functions, variables, and asms

ftracer
Common Report Var(flag_tracer)
Perform superblock formation via tail duplication

; Zero means that floating-point math operations cannot generate a
; (user-visible) trap.  This is the case, for example, in nonstop
; IEEE 754 arithmetic.
ftrapping-math
Common Report Var(flag_trapping_math) Init(1) Optimization
Assume floating-point operations can trap

ftrapv
Common Report Var(flag_trapv) Optimization
Trap for signed overflow in addition, subtraction and multiplication

ftree-ccp
Common Report Var(flag_tree_ccp) Optimization
Enable SSA-CCP optimization on trees

ftree-store-ccp
Common Report Var(flag_tree_store_ccp) Optimization
Enable SSA-CCP optimization for stores and loads

ftree-ch
Common Report Var(flag_tree_ch) Optimization
Enable loop header copying on trees

ftree-copyrename
Common Report Var(flag_tree_copyrename) Optimization
Replace SSA temporaries with better names in copies

ftree-copy-prop
Common Report Var(flag_tree_copy_prop) Optimization
Enable copy propagation on trees

ftree-store-copy-prop
Common
Does nothing.  Preserved for backward compatibility.

ftree-cselim
Common Report Var(flag_tree_cselim) Init(2) Optimization
Transform condition stores into unconditional ones

ftree-switch-conversion
Common Report Var(flag_tree_switch_conversion) Optimization
Perform conversions of switch initializations.

ftree-dce
Common Report Var(flag_tree_dce) Optimization
Enable SSA dead code elimination optimization on trees

ftree-dominator-opts
Common Report Var(flag_tree_dom) Optimization
Enable dominator optimizations

ftree-dse
Common Report Var(flag_tree_dse) Optimization
Enable dead store elimination

ftree-fre
Common Report Var(flag_tree_fre) Optimization
Enable Full Redundancy Elimination (FRE) on trees

ftree-loop-distribution
Common Report Var(flag_tree_loop_distribution) Optimization
Enable loop distribution on trees

ftree-loop-im
Common Report Var(flag_tree_loop_im) Init(1) Optimization
Enable loop invariant motion on trees

ftree-loop-linear
Common Report Var(flag_tree_loop_linear) Optimization
Enable linear loop transforms on trees

ftree-loop-ivcanon
Common Report Var(flag_tree_loop_ivcanon) Init(1) Optimization
Create canonical induction variables in loops

ftree-loop-optimize
Common Report Var(flag_tree_loop_optimize) Init(1) Optimization
Enable loop optimizations on tree level

ftree-parallelize-loops=
Common Report Joined UInteger Var(flag_tree_parallelize_loops) Init(1)
Enable automatic parallelization of loops

ftree-pre
Common Report Var(flag_tree_pre) Optimization
Enable SSA-PRE optimization on trees

ftree-reassoc
Common Report Var(flag_tree_reassoc) Init(1) Optimization
Enable reassociation on tree level

ftree-salias
Common
Does nothing.  Preserved for backward compatibility.

ftree-sink
Common Report Var(flag_tree_sink) Optimization
Enable SSA code sinking on trees

ftree-sra
Common Report Var(flag_tree_sra) Optimization
Perform scalar replacement of aggregates

ftree-ter
Common Report Var(flag_tree_ter) Init(1) Optimization
Replace temporary expressions in the SSA->normal pass

ftree-lrs
Common Report Var(flag_tree_live_range_split) Optimization
Perform live range splitting during the SSA->normal pass

ftree-vrp
Common Report Var(flag_tree_vrp) Init(0) Optimization
Perform Value Range Propagation on trees

funit-at-a-time
Common Report Var(flag_unit_at_a_time) Init(1) Optimization
Compile whole compilation unit at a time

funroll-loops
Common Report Var(flag_unroll_loops) Optimization
Perform loop unrolling when iteration count is known

funroll-all-loops
Common Report Var(flag_unroll_all_loops) Optimization
Perform loop unrolling for all loops

; Nonzero means that loop optimizer may assume that the induction variables
; that control loops do not overflow and that the loops with nontrivial
; exit condition are not infinite
funsafe-loop-optimizations
Common Report Var(flag_unsafe_loop_optimizations) Optimization
Allow loop optimizations to assume that the loops behave in normal way

fassociative-math
Common Report Var(flag_associative_math)
Allow optimization for floating-point arithmetic which may change the
result of the operation due to rounding.

freciprocal-math
Common Report Var(flag_reciprocal_math)
Same as -fassociative-math for expressions which include division.

; Nonzero means that unsafe floating-point math optimizations are allowed
; for the sake of speed.  IEEE compliance is not guaranteed, and operations
; are allowed to assume that their arguments and results are "normal"
; (e.g., nonnegative for SQRT).
funsafe-math-optimizations
Common Report Var(flag_unsafe_math_optimizations) Optimization
Allow math optimizations that may violate IEEE or ISO standards

funswitch-loops
Common Report Var(flag_unswitch_loops) Optimization
Perform loop unswitching

funwind-tables
Common Report Var(flag_unwind_tables) Optimization
Just generate unwind tables for exception handling

fvar-tracking
Common Report Var(flag_var_tracking) VarExists Optimization
Perform variable tracking

fvar-tracking-uninit
Common Report Var(flag_var_tracking_uninit) Optimization
Perform variable tracking and also tag variables that are uninitialized

ftree-vectorize
Common Report Var(flag_tree_vectorize) Optimization
Enable loop vectorization on trees

fvect-cost-model
Common Report Var(flag_vect_cost_model) Optimization
Enable use of cost model in vectorization

ftree-vect-loop-version
Common Report Var(flag_tree_vect_loop_version) Init(1) Optimization
Enable loop versioning when doing loop vectorization on trees

ftree-vectorizer-verbose=
Common RejectNegative Joined
-ftree-vectorizer-verbose=<number>	Set the verbosity level of the vectorizer

ftree-scev-cprop
Common Report Var(flag_tree_scev_cprop) Init(1) Optimization
Enable copy propagation of scalar-evolution information.

; -fverbose-asm causes extra commentary information to be produced in
; the generated assembly code (to make it more readable).  This option
; is generally only of use to those who actually need to read the
; generated assembly code (perhaps while debugging the compiler itself).
; -fno-verbose-asm, the default, causes the extra information
; to not be added and is useful when comparing two assembler files.
fverbose-asm
Common Report Var(flag_verbose_asm)
Add extra commentary to assembler output

fvisibility=
Common Joined RejectNegative
-fvisibility=[default|internal|hidden|protected]	Set the default symbol visibility


fvpt
Common Report Var(flag_value_profile_transformations) Optimization
Use expression value profiles in optimizations

fweb
Common Report Var(flag_web) Init(2) Optimization
Construct webs and split unrelated uses of single variable

ftree-builtin-call-dce
Common Report Var(flag_tree_builtin_call_dce) Init(0) Optimization
Enable conditional dead code elimination for builtin calls

fwhole-program
Common Report Var(flag_whole_program) Init(0) Optimization
Perform whole program optimizations

fwrapv
Common Report Var(flag_wrapv) Optimization
Assume signed arithmetic overflow wraps around

fzero-initialized-in-bss
Common Report Var(flag_zero_initialized_in_bss) Init(1)
Put zero initialized data in the bss section

g
Common JoinedOrMissing
Generate debug information in default format

gcoff
Common JoinedOrMissing Negative(gdwarf-2)
Generate debug information in COFF format

gdwarf-2
Common JoinedOrMissing Negative(gstabs)
Generate debug information in DWARF v2 format

ggdb
Common JoinedOrMissing
Generate debug information in default extended format

gstabs
Common JoinedOrMissing Negative(gstabs+)
Generate debug information in STABS format

gstabs+
Common JoinedOrMissing Negative(gvms)
Generate debug information in extended STABS format

gvms
Common JoinedOrMissing Negative(gxcoff)
Generate debug information in VMS format

gxcoff
Common JoinedOrMissing Negative(gxcoff+)
Generate debug information in XCOFF format

gxcoff+
Common JoinedOrMissing Negative(gcoff)
Generate debug information in extended XCOFF format

o
Common Joined Separate
-o <file>	Place output into <file>

p
Common Var(profile_flag)
Enable function profiling

pedantic
Common Var(pedantic)
Issue warnings needed for strict compliance to the standard

pedantic-errors
Common
Like -pedantic but issue them as errors

quiet
Common Var(quiet_flag)
Do not display functions compiled or elapsed time

version
Common Var(version_flag)
Display the compiler's version

w
Common Var(inhibit_warnings)
Suppress warnings

shared
Common RejectNegative Negative(pie)
Create a shared library

pie
Common RejectNegative Negative(shared)
Create a position independent executable

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