1 ; Options for the language- and target-independent parts of the compiler.
3 ; Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
4 ; Free Software Foundation, Inc.
6 ; This file is part of GCC.
8 ; GCC is free software; you can redistribute it and/or modify it under
9 ; the terms of the GNU General Public License as published by the Free
10 ; Software Foundation; either version 3, or (at your option) any later
13 ; GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 ; WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 ; FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 ; You should have received a copy of the GNU General Public License
19 ; along with GCC; see the file COPYING3. If not see
20 ; <http://www.gnu.org/licenses/>.
22 ; See the GCC internals manual (options.texi) for a description of this file's format.
24 ; Please try to keep this file in ASCII collating order.
28 Display this information
32 --help=<class> Display descriptions of a specific class of options. <class> is one or more of optimizers, target, warnings, undocumented, params
36 Alias for --help=target
38 ;; The following four entries are to work around the gcc driver
39 ;; program's insatiable desire to turn options starting with a
40 ;; double dash (--) into options starting with a dash f (-f).
55 --param <param>=<value> Set parameter <param> to value. See below for a complete list of parameters
61 Common JoinedOrMissing Optimization
62 -O<number> Set optimization level to <number>
66 Optimize for space rather than speed
70 Optimize for speed disregarding exact standards compliance
73 Common RejectNegative Var(extra_warnings) Warning
74 This switch is deprecated; use -Wextra instead
77 Common Var(warn_aggregate_return) Warning
78 Warn about returning structures, unions or arrays
81 Common Var(warn_array_bounds) Warning
82 Warn if an array is accessed out of bounds
85 Common Var(warn_attributes) Init(1) Warning
86 Warn about inappropriate attribute usage
89 Common Var(warn_cast_align) Warning
90 Warn about pointer casts which increase alignment
93 Common Var(warn_cpp) Init(1) Warning
94 Warn when a #warning directive is encountered
96 Wdeprecated-declarations
97 Common Var(warn_deprecated_decl) Init(1) Warning
98 Warn about uses of __attribute__((deprecated)) declarations
100 Wdisabled-optimization
101 Common Var(warn_disabled_optimization) Warning
102 Warn when an optimization pass is disabled
105 Common Var(warnings_are_errors)
106 Treat all warnings as errors
110 Treat specified warning as error
113 Common Var(extra_warnings) Warning
114 Print extra (possibly unwanted) warnings
117 Common Var(flag_fatal_errors)
118 Exit on the first error occurred
121 Common RejectNegative Joined UInteger
122 -Wframe-larger-than=<number> Warn if a function's stack frame requires more than <number> bytes
125 Common Var(warn_inline) Warning
126 Warn when an inlined function cannot be inlined
129 Common RejectNegative Joined UInteger Warning Undocumented
132 Common RejectNegative Joined UInteger Warning
133 -Wlarger-than=<number> Warn if an object is larger than <number> bytes
135 Wunsafe-loop-optimizations
136 Common Var(warn_unsafe_loop_optimizations) Warning
137 Warn if the loop cannot be optimized due to nontrivial assumptions.
140 Common Var(warn_missing_noreturn) Warning
141 Warn about functions which might be candidates for __attribute__((noreturn))
144 Common Var(warn_mudflap) Init(1) Warning
145 Warn about constructs not instrumented by -fmudflap
148 Common Var(warn_overflow) Init(1) Warning
149 Warn about overflow in arithmetic expressions
152 Common Var(warn_packed) Warning
153 Warn when the packed attribute has no effect on struct layout
156 Common Var(warn_padded) Warning
157 Warn when padding is required to align structure members
160 Common Var(warn_shadow) Warning
161 Warn when one local variable shadows another
164 Common Var(warn_stack_protect) Warning
165 Warn when not issuing stack smashing protection for some reason
169 Warn about code which might break strict aliasing rules
172 Common Joined RejectNegative UInteger Var(warn_strict_aliasing) Init(-1) Warning
173 Warn about code which might break strict aliasing rules
177 Warn about optimizations that assume that signed overflow is undefined
180 Common Joined RejectNegative UInteger Var(warn_strict_overflow) Init(-1) Warning
181 Warn about optimizations that assume that signed overflow is undefined
183 Wsuggest-attribute=const
184 Common Var(warn_suggest_attribute_const) Warning
185 Warn about functions which might be candidates for __attribute__((const))
187 Wsuggest-attribute=pure
188 Common Var(warn_suggest_attribute_pure) Warning
189 Warn about functions which might be candidates for __attribute__((pure))
191 Wsuggest-attribute=noreturn
192 Common Var(warn_suggest_attribute_noreturn) Warning
193 Warn about functions which might be candidates for __attribute__((noreturn))
196 Common Var(warn_switch) Warning
197 Warn about enumerated switches, with no default, missing a case
200 Common Var(warn_switch_default) Warning
201 Warn about enumerated switches missing a \"default:\" statement
204 Common Var(warn_switch_enum) Warning
205 Warn about all enumerated switches missing a specific case
208 Common Var(warn_system_headers) Warning
209 Do not suppress warnings from system headers
212 Common Var(warn_trampolines) Warning
213 Warn whenever a trampoline is generated
216 Common Var(warn_type_limits) Init(-1) Warning
217 Warn if a comparison is always true or always false due to the limited range of the data type
220 Common Var(warn_uninitialized) Init(-1) Warning
221 Warn about uninitialized automatic variables
225 Does nothing. Preserved for backward compatibility.
228 Common Var(warn_unused) Init(0) Warning
229 Enable all -Wunused- warnings
231 Wunused-but-set-parameter
232 Common Var(warn_unused_but_set_parameter) Init(-1) Warning
233 Warn when a function parameter is only set, otherwise unused
235 Wunused-but-set-variable
236 Common Var(warn_unused_but_set_variable) Init(-1) Warning
237 Warn when a variable is only set, otherwise unused
240 Common Var(warn_unused_function) Init(-1) Warning
241 Warn when a function is unused
244 Common Var(warn_unused_label) Init(-1) Warning
245 Warn when a label is unused
248 Common Var(warn_unused_parameter) Init(-1) Warning
249 Warn when a function parameter is unused
252 Common Var(warn_unused_value) Init(-1) Warning
253 Warn when an expression value is unused
256 Common Var(warn_unused_variable) Init(-1) Warning
257 Warn when a variable is unused
260 Common Var(warn_coverage_mismatch) Init(1) Warning
261 Warn in case profiles in -fprofile-use do not match
265 -aux-info <file> Emit declaration information into <file>
278 -d<letters> Enable dumps from specific passes of the compiler
282 -dumpbase <file> Set the file basename to be used for dumps
286 -dumpdir <dir> Set the directory name to be used for dumps
288 ; The version of the C++ ABI in use. The following values are allowed:
290 ; 0: The version of the ABI believed most conformant with the C++ ABI
291 ; specification. This ABI may change as bugs are discovered and fixed.
292 ; Therefore, 0 will not necessarily indicate the same ABI in different
295 ; 1: The version of the ABI first used in G++ 3.2.
297 ; 2: The version of the ABI first used in G++ 3.4 (and current default).
299 ; 3: The version of the ABI that fixes the missing underscore
300 ; in template non-type arguments of pointer type.
302 ; 4: The version of the ABI that introduces unambiguous mangling of
305 ; Additional positive integers will be assigned as new versions of
306 ; the ABI become the default version of the ABI.
308 Common Joined RejectNegative UInteger Var(flag_abi_version) Init(2)
311 Common Report Var(align_functions,0) Optimization UInteger
312 Align the start of functions
315 Common RejectNegative Joined UInteger
318 Common Report Var(align_jumps,0) Optimization UInteger
319 Align labels which are only reached by jumping
322 Common RejectNegative Joined UInteger
325 Common Report Var(align_labels,0) Optimization UInteger
329 Common RejectNegative Joined UInteger
332 Common Report Var(align_loops) Optimization UInteger
333 Align the start of loops
336 Common RejectNegative Joined UInteger
340 Does nothing. Preserved for backward compatibility.
344 Does nothing. Preserved for backward compatibility.
346 fargument-noalias-global
348 Does nothing. Preserved for backward compatibility.
350 fargument-noalias-anything
352 Does nothing. Preserved for backward compatibility.
354 fasynchronous-unwind-tables
355 Common Report Var(flag_asynchronous_unwind_tables) Optimization
356 Generate unwind tables that are exact at each instruction boundary
359 Common Report Var(flag_auto_inc_dec) Init(1)
360 Generate auto-inc/dec instructions
362 ; -fcheck-bounds causes gcc to generate array bounds checks.
363 ; For C, C++ and ObjC: defaults off.
364 ; For Java: defaults to on.
365 ; For Fortran: defaults to off.
367 Common Report Var(flag_bounds_check)
368 Generate code to check bounds before indexing arrays
371 Common Report Var(flag_branch_on_count_reg) Init(1) Optimization
372 Replace add, compare, branch with branch on count register
374 fbranch-probabilities
375 Common Report Var(flag_branch_probabilities) Optimization
376 Use profiling information for branch probabilities
378 fbranch-target-load-optimize
379 Common Report Var(flag_branch_target_load_optimize) Optimization
380 Perform branch target load optimization before prologue / epilogue threading
382 fbranch-target-load-optimize2
383 Common Report Var(flag_branch_target_load_optimize2) Optimization
384 Perform branch target load optimization after prologue / epilogue threading
387 Common Report Var(flag_btr_bb_exclusive) Optimization
388 Restrict target load migration not to re-use registers in any basic block
391 Common Joined RejectNegative
392 -fcall-saved-<register> Mark <register> as being preserved across functions
395 Common Joined RejectNegative
396 -fcall-used-<register> Mark <register> as being corrupted by function calls
398 ; Nonzero for -fcaller-saves: allocate values in regs that need to
399 ; be saved across function calls, if that produces overall better code.
400 ; Optional now, so people can test it.
402 Common Report Var(flag_caller_saves) Optimization
403 Save registers around function calls
406 Common Report Var(flag_check_data_deps)
407 Compare the results of several data dependence analyzers.
410 Common Report Var(flag_no_common,0) Optimization
411 Do not put uninitialized globals in the common section
414 Common JoinedOrMissing RejectNegative Var(flag_compare_debug_opt)
415 -fcompare-debug[=<opts>] Compile with and without e.g. -gtoggle, and compare the final-insns dump
417 fcompare-debug-second
418 Common RejectNegative Var(flag_compare_debug)
419 Run only the second compilation of -fcompare-debug
422 Common Var(flag_conserve_stack) Optimization
423 Do not perform optimizations increasing noticeably stack usage
426 Common Report Var(flag_cprop_registers) Optimization
427 Perform a register copy-propagation optimization pass
430 Common Report Var(flag_crossjumping) Optimization
431 Perform cross-jumping optimization
434 Common Report Var(flag_cse_follow_jumps) Optimization
435 When running CSE, follow jumps to their targets
439 Does nothing. Preserved for backward compatibility.
442 Common Report Var(flag_cx_limited_range) Optimization
443 Omit range reduction step when performing complex division
446 Common Report Var(flag_cx_fortran_rules) Optimization
447 Complex multiplication and division follow Fortran rules
450 Common Report Var(flag_data_sections) Optimization
451 Place data items into their own section
455 List all available debugging counters with their limits and counts.
458 Common RejectNegative Joined
459 -fdbg-cnt=<counter>:<limit>[,<counter>:<limit>,...] Set the debug counter limit.
462 Common Joined RejectNegative
463 Map one directory name to another in debug information
465 ; Nonzero for -fdefer-pop: don't pop args after each function call
466 ; instead save them up to pop many calls' args with one insns.
468 Common Report Var(flag_defer_pop) Optimization
469 Defer popping functions args from stack until later
472 Common Report Var(flag_delayed_branch) Optimization
473 Attempt to fill delay slots of branch instructions
475 fdelete-null-pointer-checks
476 Common Report Var(flag_delete_null_pointer_checks) Init(1) Optimization
477 Delete useless null pointer checks
479 fdiagnostics-show-location=
480 Common Joined RejectNegative
481 -fdiagnostics-show-location=[once|every-line] How often to emit source location at the beginning of line-wrapped diagnostics
483 fdiagnostics-show-option
484 Common Var(flag_diagnostics_show_option) Init(1)
485 Amend appropriate diagnostic messages with the command line option that controls them
488 Common Joined RejectNegative
489 -fdump-<type> Dump various compiler internals to a file
492 Common RejectNegative Joined Var(flag_dump_final_insns)
493 -fdump-final-insns=filename Dump to filename the insns at the end of translation
496 Common Report Var(flag_dump_noaddr)
497 Suppress output of addresses in debugging dumps
500 Common Report Var(flag_dump_unnumbered) VarExists
501 Suppress output of instruction numbers, line number notes and addresses in debugging dumps
503 fdump-unnumbered-links
504 Common Report Var(flag_dump_unnumbered_links) VarExists
505 Suppress output of previous and next insn numbers in debugging dumps
508 Common Report Var(flag_dwarf2_cfi_asm) Init(HAVE_GAS_CFI_DIRECTIVE)
509 Enable CFI tables via GAS assembler directives.
512 Common Report Var(flag_early_inlining) Init(1) Optimization
513 Perform early inlining
515 feliminate-dwarf2-dups
516 Common Report Var(flag_eliminate_dwarf2_dups)
517 Perform DWARF2 duplicate elimination
520 Common Report Var(flag_ipa_sra) Init(0) Optimization
521 Perform interprocedural reduction of aggregates
523 feliminate-unused-debug-symbols
524 Common Report Var(flag_debug_only_used_symbols)
525 Perform unused type elimination in debug info
527 feliminate-unused-debug-types
528 Common Report Var(flag_eliminate_unused_debug_types) Init(1)
529 Perform unused type elimination in debug info
531 femit-class-debug-always
532 Common Report Var(flag_emit_class_debug_always) Init(0)
533 Do not suppress C++ class debug information.
536 Common Report Var(flag_enable_icf_debug)
537 Generate debug information to support Identical Code Folding (ICF)
540 Common Report Var(flag_exceptions) Optimization
541 Enable exception handling
543 fexpensive-optimizations
544 Common Report Var(flag_expensive_optimizations) Optimization
545 Perform a number of minor, expensive optimizations
548 Common Joined RejectNegative
549 -fexcess-precision=[fast|standard] Specify handling of excess floating-point precision
555 Common Report Var(flag_finite_math_only) Optimization
556 Assume no NaNs or infinities are generated
559 Common Joined RejectNegative
560 -ffixed-<register> Mark <register> as being unavailable to the compiler
563 Common Report Var(flag_float_store) Optimization
564 Don't allocate floats and doubles in extended-precision registers
568 Does nothing. Preserved for backward compatibility.
571 Common Report Var(flag_forward_propagate) Optimization
572 Perform a forward propagation pass on RTL
574 ; Nonzero means don't put addresses of constant functions in registers.
575 ; Used for compiling the Unix kernel, where strange substitutions are
576 ; done on the assembly output.
578 Common Report Var(flag_no_function_cse,0)
579 Allow function addresses to be held in registers
582 Common Report Var(flag_function_sections)
583 Place each function into its own section
586 Common Report Var(flag_gcse) Optimization
587 Perform global common subexpression elimination
590 Common Report Var(flag_gcse_lm) Init(1) Optimization
591 Perform enhanced load motion during global common subexpression elimination
594 Common Report Var(flag_gcse_sm) Init(0) Optimization
595 Perform store motion after global common subexpression elimination
598 Common Report Var(flag_gcse_las) Init(0) Optimization
599 Perform redundant load after store elimination in global common subexpression
603 Common Report Var(flag_gcse_after_reload) Optimization
604 Perform global common subexpression elimination after register allocation
607 ; This option is not documented yet as its semantics will change.
609 Common Report Var(flag_graphite)
610 Enable in and out of Graphite representation
613 Common Report Var(flag_graphite_identity) Optimization
614 Enable Graphite Identity transformation
616 floop-parallelize-all
617 Common Report Var(flag_loop_parallelize_all) Optimization
618 Mark all loops as parallel
621 Common Report Var(flag_loop_strip_mine) Optimization
622 Enable Loop Strip Mining transformation
625 Common Report Var(flag_loop_interchange) Optimization
626 Enable Loop Interchange transformation
629 Common Report Var(flag_loop_block) Optimization
630 Enable Loop Blocking transformation
632 fstrict-volatile-bitfields
633 Common Report Var(flag_strict_volatile_bitfields) Init(-1)
634 Force bitfield accesses to match their type width
636 fguess-branch-probability
637 Common Report Var(flag_guess_branch_prob) Optimization
638 Enable guessing of branch probabilities
640 ; Nonzero means ignore `#ident' directives. 0 means handle them.
641 ; Generate position-independent code for executables if possible
642 ; On SVR4 targets, it also controls whether or not to emit a
643 ; string identifying the compiler.
645 Common Report Var(flag_no_ident,0)
646 Process #ident directives
649 Common Report Var(flag_if_conversion) Optimization
650 Perform conversion of conditional jumps to branchless equivalents
653 Common Report Var(flag_if_conversion2) Optimization
654 Perform conversion of conditional jumps to conditional execution
656 ftree-loop-if-convert
657 Common Report Var(flag_tree_loop_if_convert) Init(-1) Optimization
658 Convert conditional jumps in innermost loops to branchless equivalents
660 ; -finhibit-size-directive inhibits output of .size for ELF.
661 ; This is used only for compiling crtstuff.c,
662 ; and it may be extended to other effects
663 ; needed for crtstuff.c on other systems.
664 finhibit-size-directive
665 Common Report Var(flag_inhibit_size_directive)
666 Do not generate .size directives
669 Common Report Var(flag_indirect_inlining)
670 Perform indirect inlining
672 ; Nonzero means that functions declared `inline' will be treated
673 ; as `static'. Prevents generation of zillions of copies of unused
674 ; static inline functions; instead, `inlines' are written out
675 ; only when actually used. Used in conjunction with -g. Also
676 ; does the right thing with #pragma interface.
678 Common Report Var(flag_no_inline,0) Init(0)
679 Pay attention to the \"inline\" keyword
681 finline-small-functions
682 Common Report Var(flag_inline_small_functions) Optimization
683 Integrate simple functions into their callers when code size is known to not growth
686 Common Report Var(flag_inline_functions) Optimization
687 Integrate simple functions into their callers
689 finline-functions-called-once
690 Common Report Var(flag_inline_functions_called_once) Init(1) Optimization
691 Integrate functions called once into their callers
694 Common RejectNegative Joined UInteger
697 Common RejectNegative Joined UInteger
698 -finline-limit=<number> Limit the size of inlined functions to <number>
700 finstrument-functions
701 Common Report Var(flag_instrument_function_entry_exit)
702 Instrument function entry and exit with profiling calls
704 finstrument-functions-exclude-function-list=
705 Common RejectNegative Joined
706 -finstrument-functions-exclude-function-list=name,... Do not instrument listed functions
708 finstrument-functions-exclude-file-list=
709 Common RejectNegative Joined
710 -finstrument-functions-exclude-file-list=filename,... Do not instrument functions listed in files
713 Common Report Var(flag_ipa_cp) Optimization
714 Perform Interprocedural constant propagation
717 Common Report Var(flag_ipa_cp_clone) Optimization
718 Perform cloning to make Interprocedural constant propagation stronger
721 Common Report Var(flag_ipa_profile) Init(0) Optimization
722 Perform interprocedural profile propagation
725 Common Report Var(flag_ipa_pta) Init(0) Optimization
726 Perform interprocedural points-to analysis
729 Common Report Var(flag_ipa_pure_const) Init(0) Optimization
730 Discover pure and const functions
733 Common Report Var(flag_ipa_reference) Init(0) Optimization
734 Discover readonly and non addressable static variables
737 Common Report Var(flag_ipa_matrix_reorg) Optimization
738 Perform matrix layout flattening and transposing based
739 on profiling information.
742 Common Report Var(flag_ipa_struct_reorg)
743 Perform structure layout optimizations based
744 on profiling information.
747 Common Joined RejectNegative
748 -fira-algorithm=[CB|priority] Set the used IRA algorithm
751 Common Joined RejectNegative
752 -fira-region=[one|all|mixed] Set regions for IRA
755 Common Report Var(flag_ira_coalesce) Init(0)
756 Do optimistic coalescing.
759 Common Report Var(flag_ira_loop_pressure)
760 Use IRA based register pressure calculation
761 in RTL loop optimizations.
763 fira-share-save-slots
764 Common Report Var(flag_ira_share_save_slots) Init(1)
765 Share slots for saving different hard registers.
767 fira-share-spill-slots
768 Common Report Var(flag_ira_share_spill_slots) Init(1)
769 Share stack slots for spilled pseudo-registers.
772 Common RejectNegative Joined UInteger Var(flag_ira_verbose) Init(5)
773 -fira-verbose=<number> Control IRA's level of diagnostic messages.
776 Common Report Var(flag_ivopts) Init(1) Optimization
777 Optimize induction variables on trees
780 Common Var(flag_jump_tables) Init(1) Optimization
781 Use jump tables for sufficiently large switch statements
783 fkeep-inline-functions
784 Common Report Var(flag_keep_inline_functions)
785 Generate code for functions even if they are fully inlined
788 Common Report Var(flag_keep_static_consts) Init(1)
789 Emit static const variables even if they are not used
792 Common Report Var(flag_leading_underscore) Init(-1)
793 Give external symbols a leading underscore
797 Does nothing. Preserved for backward compatibility.
801 Enable link-time optimization.
803 ; The initial value of -1 comes from Z_DEFAULT_COMPRESSION in zlib.h.
804 flto-compression-level=
805 Common Joined RejectNegative UInteger Var(flag_lto_compression_level) Init(-1)
806 -flto-compression-level=<number> Use zlib compression level <number> for IL
809 Common Report Var(flag_lto_report) Init(0) Optimization
810 Report various link-time optimization statistics
813 Common Report Var(flag_errno_math) Init(1) Optimization
814 Set errno after built-in math functions
817 Common Report Var(mem_report)
818 Report on permanent memory allocation
820 ; This will attempt to merge constant section constants, if 1 only
821 ; string constants and constants from constant pool, if 2 also constant
824 Common Report Var(flag_merge_constants,2) Init(1) Optimization
825 Attempt to merge identical constants and constant variables
828 Common Report Var(flag_merge_constants,1) VarExists Optimization
829 Attempt to merge identical constants across compilation units
832 Common Report Var(flag_merge_debug_strings) Init(1)
833 Attempt to merge identical debug strings across compilation units
836 Common RejectNegative Joined UInteger
837 -fmessage-length=<number> Limit diagnostics to <number> characters per line. 0 suppresses line-wrapping
840 Common Report Var(flag_modulo_sched) Optimization
841 Perform SMS based modulo scheduling before the first scheduling pass
843 fmodulo-sched-allow-regmoves
844 Common Report Var(flag_modulo_sched_allow_regmoves)
845 Perform SMS based modulo scheduling with register moves allowed
847 fmove-loop-invariants
848 Common Report Var(flag_move_loop_invariants) Init(1) Optimization
849 Move loop invariant computations out of loops
852 Common RejectNegative Report Var(flag_mudflap)
853 Add mudflap bounds-checking instrumentation for single-threaded program
856 Common RejectNegative Report VarExists Var(flag_mudflap,2)
857 Add mudflap bounds-checking instrumentation for multi-threaded program
860 Common RejectNegative Report Var(flag_mudflap_ignore_reads)
861 Ignore read operations when inserting mudflap instrumentation
864 Common Var(flag_dce) Init(1) Optimization
865 Use the RTL dead code elimination pass
868 Common Var(flag_dse) Init(1) Optimization
869 Use the RTL dead store elimination pass
871 freschedule-modulo-scheduled-loops
872 Common Report Var(flag_resched_modulo_sched) Optimization
873 Enable/Disable the traditional scheduling in loops that already passed modulo scheduling
876 Common Report Var(flag_non_call_exceptions) Optimization
877 Support synchronous non-call exceptions
880 Common Report Var(flag_omit_frame_pointer) Optimization
881 When possible do not generate stack frames
883 foptimize-register-move
884 Common Report Var(flag_regmove) Optimization
885 Do the full register move optimization pass
887 foptimize-sibling-calls
888 Common Report Var(flag_optimize_sibling_calls) Optimization
889 Optimize sibling and tail recursive calls
892 Common Report Var(flag_partial_inlining)
893 Perform partial inlining
896 Common Report Var(pre_ipa_mem_report)
897 Report on memory allocation before interprocedural optimization
900 Common Report Var(post_ipa_mem_report)
901 Report on memory allocation before interprocedural optimization
904 Common Report Var(flag_pack_struct) Optimization
905 Pack structure members together without holes
908 Common RejectNegative Joined UInteger Optimization
909 -fpack-struct=<number> Set initial maximum structure member alignment
912 Common Report Var(flag_pcc_struct_return,1) Init(DEFAULT_PCC_STRUCT_RETURN)
913 Return small aggregates in memory, not registers
916 Common Report Var(flag_peel_loops) Optimization
920 Common Report Var(flag_no_peephole,0) Optimization
921 Enable machine specific peephole optimizations
924 Common Report Var(flag_peephole2) Optimization
925 Enable an RTL peephole pass before sched2
928 Common Report Var(flag_pic,2)
929 Generate position-independent code if possible (large mode)
932 Common Report Var(flag_pie,2)
933 Generate position-independent code for executables if possible (large mode)
936 Common Report Var(flag_pic,1) VarExists
937 Generate position-independent code if possible (small mode)
940 Common Report Var(flag_pie,1) VarExists
941 Generate position-independent code for executables if possible (small mode)
944 Common Joined RejectNegative
945 Specify a plugin to load
948 Common Joined RejectNegative
949 -fplugin-arg-<name>-<key>[=<value>] Specify argument <key>=<value> for plugin <name>
951 fpredictive-commoning
952 Common Report Var(flag_predictive_commoning) Optimization
953 Run predictive commoning optimization.
955 fprefetch-loop-arrays
956 Common Report Var(flag_prefetch_loop_arrays) Init(-1) Optimization
957 Generate prefetch instructions, if available, for arrays in loops
960 Common Report Var(profile_flag)
961 Enable basic program profiling code
964 Common Report Var(profile_arc_flag)
965 Insert arc-based program profiling code
968 Common Joined RejectNegative
969 Set the top-level directory for storing the profile data.
970 The default is 'pwd'.
973 Common Report Var(flag_profile_correction)
974 Enable correction of flow inconsistent profile data input
978 Enable common options for generating profile info for profile feedback directed optimizations
981 Common Joined RejectNegative
982 Enable common options for generating profile info for profile feedback directed optimizations, and set -fprofile-dir=
985 Common Var(flag_profile_use)
986 Enable common options for performing profile feedback directed optimizations
989 Common Joined RejectNegative
990 Enable common options for performing profile feedback directed optimizations, and set -fprofile-dir=
993 Common Report Var(flag_profile_values)
994 Insert code to profile values of expressions
1000 Common Joined RejectNegative
1001 -frandom-seed=<string> Make compile reproducible using <string>
1003 ; This switch causes the command line that was used to create an
1004 ; object file to be recorded into the object file. The exact format
1005 ; of this recording is target and binary file format dependent.
1006 ; It is related to the -fverbose-asm switch, but that switch only
1007 ; records information in the assembler output file as comments, so
1008 ; they never reach the object file.
1009 frecord-gcc-switches
1010 Common Report Var(flag_record_gcc_switches)
1011 Record gcc command line switches in the object file.
1014 Common Report Var(flag_pcc_struct_return,0) VarExists Optimization
1015 Return small aggregates in registers
1018 Common Report Var(flag_regmove) Optimization
1019 Enables a register move optimization
1022 Common Report Var(flag_rename_registers) Init(2) Optimization
1023 Perform a register renaming optimization pass
1026 Common Report Var(flag_reorder_blocks) Optimization
1027 Reorder basic blocks to improve code placement
1029 freorder-blocks-and-partition
1030 Common Report Var(flag_reorder_blocks_and_partition) Optimization
1031 Reorder basic blocks and partition into hot and cold sections
1034 Common Report Var(flag_reorder_functions) Optimization
1035 Reorder functions to improve code placement
1037 frerun-cse-after-loop
1038 Common Report Var(flag_rerun_cse_after_loop) Init(2) Optimization
1039 Add a common subexpression elimination pass after loop optimizations
1043 Does nothing. Preserved for backward compatibility.
1046 Common Report Var(flag_rounding_math) Optimization
1047 Disable optimizations that assume default FP rounding behavior
1050 Common Report Var(flag_schedule_interblock) Init(1) Optimization
1051 Enable scheduling across basic blocks
1054 Common Report Var(flag_sched_pressure) Init(0) Optimization
1055 Enable register pressure sensitive insn scheduling
1058 Common Report Var(flag_schedule_speculative) Init(1) Optimization
1059 Allow speculative motion of non-loads
1062 Common Report Var(flag_schedule_speculative_load) Optimization
1063 Allow speculative motion of some loads
1065 fsched-spec-load-dangerous
1066 Common Report Var(flag_schedule_speculative_load_dangerous) Optimization
1067 Allow speculative motion of more loads
1070 Common RejectNegative Joined
1071 -fsched-verbose=<number> Set the verbosity level of the scheduler
1073 fsched2-use-superblocks
1074 Common Report Var(flag_sched2_use_superblocks) Optimization
1075 If scheduling post reload, do superblock scheduling
1079 Does nothing. Preserved for backward compatibility.
1082 Common Report Var(flag_schedule_insns) Optimization
1083 Reschedule instructions before register allocation
1086 Common Report Var(flag_schedule_insns_after_reload) Optimization
1087 Reschedule instructions after register allocation
1089 ; This flag should be on when a target implements non-trivial
1090 ; scheduling hooks, maybe saving some information for its own sake.
1091 ; On IA64, for example, this is used for correct bundling.
1092 fselective-scheduling
1093 Common Report Var(flag_selective_scheduling) Optimization
1094 Schedule instructions using selective scheduling algorithm
1096 fselective-scheduling2
1097 Common Report Var(flag_selective_scheduling2) Optimization
1098 Run selective scheduling after reload
1100 fsel-sched-pipelining
1101 Common Report Var(flag_sel_sched_pipelining) Init(0) Optimization
1102 Perform software pipelining of inner loops during selective scheduling
1104 fsel-sched-pipelining-outer-loops
1105 Common Report Var(flag_sel_sched_pipelining_outer_loops) Init(0) Optimization
1106 Perform software pipelining of outer loops during selective scheduling
1108 fsel-sched-reschedule-pipelined
1109 Common Report Var(flag_sel_sched_reschedule_pipelined) Init(0) Optimization
1110 Reschedule pipelined regions without pipelining
1112 ; sched_stalled_insns means that insns can be moved prematurely from the queue
1113 ; of stalled insns into the ready list.
1114 fsched-stalled-insns
1115 Common Report Var(flag_sched_stalled_insns) Optimization UInteger
1116 Allow premature scheduling of queued insns
1118 fsched-stalled-insns=
1119 Common RejectNegative Joined UInteger
1120 -fsched-stalled-insns=<number> Set number of queued insns that can be prematurely scheduled
1122 ; sched_stalled_insns_dep controls how many recently scheduled cycles will
1123 ; be examined for a dependency on a stalled insn that is candidate for
1124 ; premature removal from the queue of stalled insns into the ready list (has
1125 ; an effect only if the flag 'sched_stalled_insns' is set).
1126 fsched-stalled-insns-dep
1127 Common Report Var(flag_sched_stalled_insns_dep,1) Init(1) Optimization UInteger
1128 Set dependence distance checking in premature scheduling of queued insns
1130 fsched-stalled-insns-dep=
1131 Common RejectNegative Joined UInteger
1132 -fsched-stalled-insns-dep=<number> Set dependence distance checking in premature scheduling of queued insns
1134 fsched-group-heuristic
1135 Common Report Var(flag_sched_group_heuristic) Init(1) Optimization
1136 Enable the group heuristic in the scheduler
1138 fsched-critical-path-heuristic
1139 Common Report Var(flag_sched_critical_path_heuristic) Init(1) Optimization
1140 Enable the critical path heuristic in the scheduler
1142 fsched-spec-insn-heuristic
1143 Common Report Var(flag_sched_spec_insn_heuristic) Init(1) Optimization
1144 Enable the speculative instruction heuristic in the scheduler
1146 fsched-rank-heuristic
1147 Common Report Var(flag_sched_rank_heuristic) Init(1) Optimization
1148 Enable the rank heuristic in the scheduler
1150 fsched-last-insn-heuristic
1151 Common Report Var(flag_sched_last_insn_heuristic) Init(1) Optimization
1152 Enable the last instruction heuristic in the scheduler
1154 fsched-dep-count-heuristic
1155 Common Report Var(flag_sched_dep_count_heuristic) Init(1) Optimization
1156 Enable the dependent count heuristic in the scheduler
1159 Common Report Var(flag_section_anchors) Optimization
1160 Access data in the same section from shared anchor points
1164 Does nothing. Preserved for backward compatibility.
1167 Common Report Var(flag_zee) Init(0)
1168 Eliminate redundant zero extensions on targets that support implicit extensions.
1171 Common Report Var(flag_show_column) Init(1)
1172 Show column numbers in diagnostics, when available. Default on
1175 Common Report Var(flag_signaling_nans) Optimization
1176 Disable optimizations observable by IEEE signaling NaNs
1179 Common Report Var(flag_signed_zeros) Init(1) Optimization
1180 Disable floating point optimizations that ignore the IEEE signedness of zero
1182 fsingle-precision-constant
1183 Common Report Var(flag_single_precision_constant) Optimization
1184 Convert floating point constants to single precision constants
1186 fsplit-ivs-in-unroller
1187 Common Report Var(flag_split_ivs_in_unroller) Init(1) Optimization
1188 Split lifetimes of induction variables when loops are unrolled
1191 Common Report Var(flag_split_wide_types) Optimization
1192 Split wide types into independent registers
1194 fvariable-expansion-in-unroller
1195 Common Report Var(flag_variable_expansion_in_unroller) Optimization
1196 Apply variable expansion when loops are unrolled
1199 Common Report RejectNegative Joined
1200 -fstack-check=[no|generic|specific] Insert stack checking code into the program
1204 Insert stack checking code into the program. Same as -fstack-check=specific
1209 fstack-limit-register=
1210 Common RejectNegative Joined
1211 -fstack-limit-register=<register> Trap if the stack goes past <register>
1213 fstack-limit-symbol=
1214 Common RejectNegative Joined
1215 -fstack-limit-symbol=<name> Trap if the stack goes past symbol <name>
1218 Common Report Var(flag_stack_protect, 1)
1219 Use propolice as a stack protection method
1221 fstack-protector-all
1222 Common Report RejectNegative Var(flag_stack_protect, 2) VarExists
1223 Use a stack protection method for every function
1227 Does nothing. Preserved for backward compatibility.
1229 ; Nonzero if we should do (language-dependent) alias analysis.
1230 ; Typically, this analysis will assume that expressions of certain
1231 ; types do not alias expressions of certain other types. Only used
1232 ; if alias analysis (in general) is enabled.
1234 Common Report Var(flag_strict_aliasing) Optimization
1235 Assume strict aliasing rules apply
1238 Common Report Var(flag_strict_overflow)
1239 Treat signed overflow as undefined
1242 Common Report Var(flag_syntax_only)
1243 Check for syntax errors, then stop
1246 Common Report Var(flag_test_coverage)
1247 Create data files needed by \"gcov\"
1250 Common Report Var(flag_thread_jumps) Optimization
1251 Perform jump threading optimizations
1254 Common Report Var(time_report)
1255 Report the time taken by each compiler pass
1258 Common Joined RejectNegative
1259 -ftls-model=[global-dynamic|local-dynamic|initial-exec|local-exec] Set the default thread-local storage code generation model
1262 Common Report Var(flag_toplevel_reorder) Init(2) Optimization
1263 Reorder top level functions, variables, and asms
1266 Common Report Var(flag_tracer)
1267 Perform superblock formation via tail duplication
1269 ; Zero means that floating-point math operations cannot generate a
1270 ; (user-visible) trap. This is the case, for example, in nonstop
1271 ; IEEE 754 arithmetic.
1273 Common Report Var(flag_trapping_math) Init(1) Optimization
1274 Assume floating-point operations can trap
1277 Common Report Var(flag_trapv) Optimization
1278 Trap for signed overflow in addition, subtraction and multiplication
1281 Common Report Var(flag_tree_ccp) Optimization
1282 Enable SSA-CCP optimization on trees
1285 Common Report Var(flag_tree_bit_ccp) Optimization
1286 Enable SSA-BIT-CCP optimization on trees
1290 Does nothing. Preserved for backward compatibility.
1293 Common Report Var(flag_tree_ch) Optimization
1294 Enable loop header copying on trees
1297 Common Report Var(flag_tree_copyrename) Optimization
1298 Replace SSA temporaries with better names in copies
1301 Common Report Var(flag_tree_copy_prop) Optimization
1302 Enable copy propagation on trees
1304 ftree-store-copy-prop
1306 Does nothing. Preserved for backward compatibility.
1309 Common Report Var(flag_tree_cselim) Init(2) Optimization
1310 Transform condition stores into unconditional ones
1312 ftree-switch-conversion
1313 Common Report Var(flag_tree_switch_conversion) Optimization
1314 Perform conversions of switch initializations.
1317 Common Report Var(flag_tree_dce) Optimization
1318 Enable SSA dead code elimination optimization on trees
1320 ftree-dominator-opts
1321 Common Report Var(flag_tree_dom) Optimization
1322 Enable dominator optimizations
1325 Common Report Var(flag_tree_dse) Optimization
1326 Enable dead store elimination
1329 Common Report Var(flag_tree_forwprop) Init(1) Optimization
1330 Enable forward propagation on trees
1333 Common Report Var(flag_tree_fre) Optimization
1334 Enable Full Redundancy Elimination (FRE) on trees
1336 ftree-loop-distribution
1337 Common Report Var(flag_tree_loop_distribution) Optimization
1338 Enable loop distribution on trees
1340 ftree-loop-distribute-patterns
1341 Common Report Var(flag_tree_loop_distribute_patterns) Optimization
1342 Enable loop distribution for patterns transformed into a library call
1345 Common Report Var(flag_tree_loop_im) Init(1) Optimization
1346 Enable loop invariant motion on trees
1349 Common Report Var(flag_tree_loop_linear) Optimization
1350 Enable linear loop transforms on trees
1353 Common Report Var(flag_tree_loop_ivcanon) Init(1) Optimization
1354 Create canonical induction variables in loops
1357 Common Report Var(flag_tree_loop_optimize) Init(1) Optimization
1358 Enable loop optimizations on tree level
1360 ftree-parallelize-loops=
1361 Common Report Joined RejectNegative UInteger Var(flag_tree_parallelize_loops) Init(1)
1362 Enable automatic parallelization of loops
1365 Common Report Var(flag_tree_phiprop) Init(1) Optimization
1366 Enable hoisting loads from conditional pointers.
1369 Common Report Var(flag_tree_pre) Optimization
1370 Enable SSA-PRE optimization on trees
1373 Common Report Var(flag_tree_pta) Init(1) Optimization
1374 Perform function-local points-to analysis on trees.
1377 Common Report Var(flag_tree_reassoc) Init(1) Optimization
1378 Enable reassociation on tree level
1382 Does nothing. Preserved for backward compatibility.
1385 Common Report Var(flag_tree_sink) Optimization
1386 Enable SSA code sinking on trees
1389 Common Report Var(flag_tree_sra) Optimization
1390 Perform scalar replacement of aggregates
1393 Common Report Var(flag_tree_ter) Init(1) Optimization
1394 Replace temporary expressions in the SSA->normal pass
1397 Common Report Var(flag_tree_live_range_split) Optimization
1398 Perform live range splitting during the SSA->normal pass
1401 Common Report Var(flag_tree_vrp) Init(0) Optimization
1402 Perform Value Range Propagation on trees
1405 Common Report Var(flag_unit_at_a_time) Init(1) Optimization
1406 Compile whole compilation unit at a time
1409 Common Report Var(flag_unroll_loops) Optimization
1410 Perform loop unrolling when iteration count is known
1413 Common Report Var(flag_unroll_all_loops) Optimization
1414 Perform loop unrolling for all loops
1416 ; Nonzero means that loop optimizer may assume that the induction variables
1417 ; that control loops do not overflow and that the loops with nontrivial
1418 ; exit condition are not infinite
1419 funsafe-loop-optimizations
1420 Common Report Var(flag_unsafe_loop_optimizations) Optimization
1421 Allow loop optimizations to assume that the loops behave in normal way
1424 Common Report Var(flag_associative_math)
1425 Allow optimization for floating-point arithmetic which may change the
1426 result of the operation due to rounding.
1429 Common Report Var(flag_reciprocal_math)
1430 Same as -fassociative-math for expressions which include division.
1432 ; Nonzero means that unsafe floating-point math optimizations are allowed
1433 ; for the sake of speed. IEEE compliance is not guaranteed, and operations
1434 ; are allowed to assume that their arguments and results are "normal"
1435 ; (e.g., nonnegative for SQRT).
1436 funsafe-math-optimizations
1437 Common Report Var(flag_unsafe_math_optimizations) Optimization
1438 Allow math optimizations that may violate IEEE or ISO standards
1441 Common Report Var(flag_unswitch_loops) Optimization
1442 Perform loop unswitching
1445 Common Report Var(flag_unwind_tables) Optimization
1446 Just generate unwind tables for exception handling
1452 Common Report Var(flag_var_tracking) VarExists Optimization
1453 Perform variable tracking
1455 fvar-tracking-assignments
1456 Common Report Var(flag_var_tracking_assignments) VarExists Optimization
1457 Perform variable tracking by annotating assignments
1459 fvar-tracking-assignments-toggle
1460 Common Report Var(flag_var_tracking_assignments_toggle) VarExists Optimization
1461 Toggle -fvar-tracking-assignments
1463 fvar-tracking-uninit
1464 Common Report Var(flag_var_tracking_uninit) Optimization
1465 Perform variable tracking and also tag variables that are uninitialized
1468 Common Report Var(flag_tree_vectorize) Optimization
1469 Enable loop vectorization on trees
1472 Common Report Var(flag_tree_slp_vectorize) Init(2) Optimization
1473 Enable basic block vectorization (SLP) on trees
1476 Common Report Var(flag_vect_cost_model) Optimization
1477 Enable use of cost model in vectorization
1479 ftree-vect-loop-version
1480 Common Report Var(flag_tree_vect_loop_version) Init(1) Optimization
1481 Enable loop versioning when doing loop vectorization on trees
1483 ftree-vectorizer-verbose=
1484 Common RejectNegative Joined
1485 -ftree-vectorizer-verbose=<number> Set the verbosity level of the vectorizer
1488 Common Report Var(flag_tree_scev_cprop) Init(1) Optimization
1489 Enable copy propagation of scalar-evolution information.
1491 ; -fverbose-asm causes extra commentary information to be produced in
1492 ; the generated assembly code (to make it more readable). This option
1493 ; is generally only of use to those who actually need to read the
1494 ; generated assembly code (perhaps while debugging the compiler itself).
1495 ; -fno-verbose-asm, the default, causes the extra information
1496 ; to not be added and is useful when comparing two assembler files.
1498 Common Report Var(flag_verbose_asm)
1499 Add extra commentary to assembler output
1502 Common Joined RejectNegative
1503 -fvisibility=[default|internal|hidden|protected] Set the default symbol visibility
1507 Common Report Var(flag_value_profile_transformations) Optimization
1508 Use expression value profiles in optimizations
1511 Common Report Var(flag_web) Init(2) Optimization
1512 Construct webs and split unrelated uses of single variable
1516 Enable partitioned link-time optimization
1519 Common RejectNegative UInteger Joined Var(flag_whopr)
1520 Enable partitioned link-time optimization with specified number of parallel jobs
1522 ftree-builtin-call-dce
1523 Common Report Var(flag_tree_builtin_call_dce) Init(0) Optimization
1524 Enable conditional dead code elimination for builtin calls
1527 Common Report Var(flag_whole_program) Init(0) Optimization
1528 Perform whole program optimizations
1531 Common Report Var(flag_wrapv) Optimization
1532 Assume signed arithmetic overflow wraps around
1534 fzero-initialized-in-bss
1535 Common Report Var(flag_zero_initialized_in_bss) Init(1)
1536 Put zero initialized data in the bss section
1539 Common JoinedOrMissing
1540 Generate debug information in default format
1543 Common JoinedOrMissing Negative(gdwarf-)
1544 Generate debug information in COFF format
1547 Common Joined UInteger Var(dwarf_version) Init(2) Negative(gstabs)
1548 Generate debug information in DWARF v2 (or later) format
1551 Common JoinedOrMissing
1552 Generate debug information in default extended format
1555 Common JoinedOrMissing Negative(gstabs+)
1556 Generate debug information in STABS format
1559 Common JoinedOrMissing Negative(gvms)
1560 Generate debug information in extended STABS format
1563 Common RejectNegative Var(dwarf_strict,0) Init(-1)
1564 Emit DWARF additions beyond selected version
1567 Common Report RejectNegative Var(dwarf_strict,1) VarExists
1568 Don't emit DWARF additions beyond selected version
1571 Common Report Var(flag_gtoggle)
1572 Toggle debug information generation
1575 Common JoinedOrMissing Negative(gxcoff)
1576 Generate debug information in VMS format
1579 Common JoinedOrMissing Negative(gxcoff+)
1580 Generate debug information in XCOFF format
1583 Common JoinedOrMissing Negative(gcoff)
1584 Generate debug information in extended XCOFF format
1587 Common Joined Var(plugindir_string) Init(0)
1588 -iplugindir=<dir> Set <dir> to be the default plugin directory
1591 Common Joined Separate MissingArgError(missing filename after %qs)
1592 -o <file> Place output into <file>
1595 Common Var(profile_flag)
1596 Enable function profiling
1599 Common Var(pedantic)
1600 Issue warnings needed for strict compliance to the standard
1604 Like -pedantic but issue them as errors
1607 Common Var(quiet_flag)
1608 Do not display functions compiled or elapsed time
1611 Common Var(version_flag)
1612 Display the compiler's version
1615 Common Var(inhibit_warnings)
1619 Common RejectNegative Negative(pie)
1620 Create a shared library
1623 Common RejectNegative Negative(shared)
1624 Create a position independent executable
1626 ; This comment is to ensure we retain the blank line above.