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 Joined Separate UInteger
62 -G<number> Put global and static data smaller than <number> bytes into a special section (on some targets)
65 Common JoinedOrMissing Optimization
66 -O<number> Set optimization level to <number>
70 Optimize for space rather than speed
74 Optimize for speed disregarding exact standards compliance
77 Common RejectNegative Var(extra_warnings) Warning
78 This switch is deprecated; use -Wextra instead
81 Common Var(warn_aggregate_return) Warning
82 Warn about returning structures, unions or arrays
85 Common Var(warn_array_bounds) Warning
86 Warn if an array is accessed out of bounds
89 Common Var(warn_attributes) Init(1) Warning
90 Warn about inappropriate attribute usage
93 Common Var(warn_cast_align) Warning
94 Warn about pointer casts which increase alignment
97 Common Var(warn_cpp) Init(1) Warning
98 Warn when a #warning directive is encountered
100 Wdeprecated-declarations
101 Common Var(warn_deprecated_decl) Init(1) Warning
102 Warn about uses of __attribute__((deprecated)) declarations
104 Wdisabled-optimization
105 Common Var(warn_disabled_optimization) Warning
106 Warn when an optimization pass is disabled
109 Common Var(warnings_are_errors)
110 Treat all warnings as errors
114 Treat specified warning as error
117 Common Var(extra_warnings) Warning
118 Print extra (possibly unwanted) warnings
121 Common Var(flag_fatal_errors)
122 Exit on the first error occurred
125 Common RejectNegative Joined UInteger
126 -Wframe-larger-than=<number> Warn if a function's stack frame requires more than <number> bytes
129 Common Var(warn_inline) Warning
130 Warn when an inlined function cannot be inlined
133 Common RejectNegative Joined UInteger Warning Undocumented
136 Common RejectNegative Joined UInteger Warning
137 -Wlarger-than=<number> Warn if an object is larger than <number> bytes
139 Wunsafe-loop-optimizations
140 Common Var(warn_unsafe_loop_optimizations) Warning
141 Warn if the loop cannot be optimized due to nontrivial assumptions.
144 Common Var(warn_missing_noreturn) Warning
145 Warn about functions which might be candidates for __attribute__((noreturn))
148 Common Var(warn_mudflap) Init(1) Warning
149 Warn about constructs not instrumented by -fmudflap
152 Common Var(warn_overflow) Init(1) Warning
153 Warn about overflow in arithmetic expressions
156 Common Var(warn_packed) Warning
157 Warn when the packed attribute has no effect on struct layout
160 Common Var(warn_padded) Warning
161 Warn when padding is required to align structure members
164 Common Var(warn_shadow) Warning
165 Warn when one local variable shadows another
168 Common Var(warn_stack_protect) Warning
169 Warn when not issuing stack smashing protection for some reason
173 Warn about code which might break strict aliasing rules
176 Common Joined UInteger Var(warn_strict_aliasing) Init(-1) Warning
177 Warn about code which might break strict aliasing rules
181 Warn about optimizations that assume that signed overflow is undefined
184 Common Joined UInteger Var(warn_strict_overflow) Init(-1) Warning
185 Warn about optimizations that assume that signed overflow is undefined
187 Wsuggest-attribute=const
188 Common Var(warn_suggest_attribute_const) Warning
189 Warn about functions which might be candidates for __attribute__((const))
191 Wsuggest-attribute=pure
192 Common Var(warn_suggest_attribute_pure) Warning
193 Warn about functions which might be candidates for __attribute__((pure))
195 Wsuggest-attribute=noreturn
196 Common Var(warn_suggest_attribute_noreturn) Warning
197 Warn about functions which might be candidates for __attribute__((noreturn))
200 Common Var(warn_switch) Warning
201 Warn about enumerated switches, with no default, missing a case
204 Common Var(warn_switch_default) Warning
205 Warn about enumerated switches missing a \"default:\" statement
208 Common Var(warn_switch_enum) Warning
209 Warn about all enumerated switches missing a specific case
212 Common Var(warn_system_headers) Warning
213 Do not suppress warnings from system headers
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 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 fguess-branch-probability
633 Common Report Var(flag_guess_branch_prob) Optimization
634 Enable guessing of branch probabilities
636 ; Nonzero means ignore `#ident' directives. 0 means handle them.
637 ; Generate position-independent code for executables if possible
638 ; On SVR4 targets, it also controls whether or not to emit a
639 ; string identifying the compiler.
641 Common Report Var(flag_no_ident,0)
642 Process #ident directives
645 Common Report Var(flag_if_conversion) Optimization
646 Perform conversion of conditional jumps to branchless equivalents
649 Common Report Var(flag_if_conversion2) Optimization
650 Perform conversion of conditional jumps to conditional execution
652 ; -finhibit-size-directive inhibits output of .size for ELF.
653 ; This is used only for compiling crtstuff.c,
654 ; and it may be extended to other effects
655 ; needed for crtstuff.c on other systems.
656 finhibit-size-directive
657 Common Report Var(flag_inhibit_size_directive)
658 Do not generate .size directives
661 Common Report Var(flag_indirect_inlining)
662 Perform indirect inlining
664 ; Nonzero means that functions declared `inline' will be treated
665 ; as `static'. Prevents generation of zillions of copies of unused
666 ; static inline functions; instead, `inlines' are written out
667 ; only when actually used. Used in conjunction with -g. Also
668 ; does the right thing with #pragma interface.
670 Common Report Var(flag_no_inline,0) Init(0)
671 Pay attention to the \"inline\" keyword
673 finline-small-functions
674 Common Report Var(flag_inline_small_functions) Optimization
675 Integrate simple functions into their callers when code size is known to not growth
678 Common Report Var(flag_inline_functions) Optimization
679 Integrate simple functions into their callers
681 finline-functions-called-once
682 Common Report Var(flag_inline_functions_called_once) Init(1) Optimization
683 Integrate functions called once into their callers
686 Common RejectNegative Joined UInteger
689 Common RejectNegative Joined UInteger
690 -finline-limit=<number> Limit the size of inlined functions to <number>
692 finstrument-functions
693 Common Report Var(flag_instrument_function_entry_exit)
694 Instrument function entry and exit with profiling calls
696 finstrument-functions-exclude-function-list=
697 Common RejectNegative Joined
698 -finstrument-functions-exclude-function-list=name,... Do not instrument listed functions
700 finstrument-functions-exclude-file-list=
701 Common RejectNegative Joined
702 -finstrument-functions-exclude-file-list=filename,... Do not instrument functions listed in files
705 Common Report Var(flag_ipa_cp) Optimization
706 Perform Interprocedural constant propagation
709 Common Report Var(flag_ipa_cp_clone) Optimization
710 Perform cloning to make Interprocedural constant propagation stronger
713 Common Report Var(flag_ipa_profile) Init(0) Optimization
714 Perform interprocedural profile propagation
717 Common Report Var(flag_ipa_pta) Init(0) Optimization
718 Perform interprocedural points-to analysis
721 Common Report Var(flag_ipa_pure_const) Init(0) Optimization
722 Discover pure and const functions
725 Common Report Var(flag_ipa_reference) Init(0) Optimization
726 Discover readonly and non addressable static variables
729 Common Report Var(flag_ipa_matrix_reorg) Optimization
730 Perform matrix layout flattening and transposing based
731 on profiling information.
734 Common Report Var(flag_ipa_struct_reorg)
735 Perform structure layout optimizations based
736 on profiling information.
739 Common Joined RejectNegative
740 -fira-algorithm=[CB|priority] Set the used IRA algorithm
743 Common Joined RejectNegative
744 -fira-region=[one|all|mixed] Set regions for IRA
747 Common Report Var(flag_ira_coalesce) Init(0)
748 Do optimistic coalescing.
751 Common Report Var(flag_ira_loop_pressure)
752 Use IRA based register pressure calculation
753 in RTL loop optimizations.
755 fira-share-save-slots
756 Common Report Var(flag_ira_share_save_slots) Init(1)
757 Share slots for saving different hard registers.
759 fira-share-spill-slots
760 Common Report Var(flag_ira_share_spill_slots) Init(1)
761 Share stack slots for spilled pseudo-registers.
764 Common RejectNegative Joined UInteger Var(flag_ira_verbose) Init(5)
765 -fira-verbose=<number> Control IRA's level of diagnostic messages.
768 Common Report Var(flag_ivopts) Init(1) Optimization
769 Optimize induction variables on trees
772 Common Var(flag_jump_tables) Init(1) Optimization
773 Use jump tables for sufficiently large switch statements
775 fkeep-inline-functions
776 Common Report Var(flag_keep_inline_functions)
777 Generate code for functions even if they are fully inlined
780 Common Report Var(flag_keep_static_consts) Init(1)
781 Emit static const variables even if they are not used
784 Common Report Var(flag_leading_underscore) Init(-1)
785 Give external symbols a leading underscore
789 Does nothing. Preserved for backward compatibility.
793 Enable link-time optimization.
795 ; The initial value of -1 comes from Z_DEFAULT_COMPRESSION in zlib.h.
796 flto-compression-level=
797 Common Joined UInteger Var(flag_lto_compression_level) Init(-1)
798 -flto-compression-level=<number> Use zlib compression level <number> for IL
801 Common Report Var(flag_lto_report) Init(0) Optimization
802 Report various link-time optimization statistics
805 Common Report Var(flag_errno_math) Init(1) Optimization
806 Set errno after built-in math functions
809 Common Report Var(mem_report)
810 Report on permanent memory allocation
812 ; This will attempt to merge constant section constants, if 1 only
813 ; string constants and constants from constant pool, if 2 also constant
816 Common Report Var(flag_merge_constants,2) Init(1) Optimization
817 Attempt to merge identical constants and constant variables
820 Common Report Var(flag_merge_constants,1) VarExists Optimization
821 Attempt to merge identical constants across compilation units
824 Common Report Var(flag_merge_debug_strings) Init(1)
825 Attempt to merge identical debug strings across compilation units
828 Common RejectNegative Joined UInteger
829 -fmessage-length=<number> Limit diagnostics to <number> characters per line. 0 suppresses line-wrapping
832 Common Report Var(flag_modulo_sched) Optimization
833 Perform SMS based modulo scheduling before the first scheduling pass
835 fmodulo-sched-allow-regmoves
836 Common Report Var(flag_modulo_sched_allow_regmoves)
837 Perform SMS based modulo scheduling with register moves allowed
839 fmove-loop-invariants
840 Common Report Var(flag_move_loop_invariants) Init(1) Optimization
841 Move loop invariant computations out of loops
844 Common RejectNegative Report Var(flag_mudflap)
845 Add mudflap bounds-checking instrumentation for single-threaded program
848 Common RejectNegative Report VarExists Var(flag_mudflap,2)
849 Add mudflap bounds-checking instrumentation for multi-threaded program
852 Common RejectNegative Report Var(flag_mudflap_ignore_reads)
853 Ignore read operations when inserting mudflap instrumentation
856 Common Var(flag_dce) Init(1) Optimization
857 Use the RTL dead code elimination pass
860 Common Var(flag_dse) Init(1) Optimization
861 Use the RTL dead store elimination pass
863 freschedule-modulo-scheduled-loops
864 Common Report Var(flag_resched_modulo_sched) Optimization
865 Enable/Disable the traditional scheduling in loops that already passed modulo scheduling
868 Common Report Var(flag_non_call_exceptions) Optimization
869 Support synchronous non-call exceptions
872 Common Report Var(flag_omit_frame_pointer) Optimization
873 When possible do not generate stack frames
875 foptimize-register-move
876 Common Report Var(flag_regmove) Optimization
877 Do the full register move optimization pass
879 foptimize-sibling-calls
880 Common Report Var(flag_optimize_sibling_calls) Optimization
881 Optimize sibling and tail recursive calls
884 Common Report Var(pre_ipa_mem_report)
885 Report on memory allocation before interprocedural optimization
888 Common Report Var(post_ipa_mem_report)
889 Report on memory allocation before interprocedural optimization
892 Common Report Var(flag_pack_struct) Optimization
893 Pack structure members together without holes
896 Common RejectNegative Joined UInteger Optimization
897 -fpack-struct=<number> Set initial maximum structure member alignment
900 Common Report Var(flag_pcc_struct_return,1) Init(DEFAULT_PCC_STRUCT_RETURN)
901 Return small aggregates in memory, not registers
904 Common Report Var(flag_peel_loops) Optimization
908 Common Report Var(flag_no_peephole,0) Optimization
909 Enable machine specific peephole optimizations
912 Common Report Var(flag_peephole2) Optimization
913 Enable an RTL peephole pass before sched2
916 Common Report Var(flag_pic,2)
917 Generate position-independent code if possible (large mode)
920 Common Report Var(flag_pie,2)
921 Generate position-independent code for executables if possible (large mode)
924 Common Report Var(flag_pic,1) VarExists
925 Generate position-independent code if possible (small mode)
928 Common Report Var(flag_pie,1) VarExists
929 Generate position-independent code for executables if possible (small mode)
932 Common Joined RejectNegative
933 Specify a plugin to load
936 Common Joined RejectNegative
937 -fplugin-arg-<name>-<key>[=<value>] Specify argument <key>=<value> for plugin <name>
939 fpredictive-commoning
940 Common Report Var(flag_predictive_commoning) Optimization
941 Run predictive commoning optimization.
943 fprefetch-loop-arrays
944 Common Report Var(flag_prefetch_loop_arrays) Optimization
945 Generate prefetch instructions, if available, for arrays in loops
948 Common Report Var(profile_flag)
949 Enable basic program profiling code
952 Common Report Var(profile_arc_flag)
953 Insert arc-based program profiling code
956 Common Joined RejectNegative
957 Set the top-level directory for storing the profile data.
958 The default is 'pwd'.
961 Common Report Var(flag_profile_correction)
962 Enable correction of flow inconsistent profile data input
966 Enable common options for generating profile info for profile feedback directed optimizations
969 Common Joined RejectNegative
970 Enable common options for generating profile info for profile feedback directed optimizations, and set -fprofile-dir=
973 Common Var(flag_profile_use)
974 Enable common options for performing profile feedback directed optimizations
977 Common Joined RejectNegative
978 Enable common options for performing profile feedback directed optimizations, and set -fprofile-dir=
981 Common Report Var(flag_profile_values)
982 Insert code to profile values of expressions
988 Common Joined RejectNegative
989 -frandom-seed=<string> Make compile reproducible using <string>
991 ; This switch causes the command line that was used to create an
992 ; object file to be recorded into the object file. The exact format
993 ; of this recording is target and binary file format dependent.
994 ; It is related to the -fverbose-asm switch, but that switch only
995 ; records information in the assembler output file as comments, so
996 ; they never reach the object file.
998 Common Report Var(flag_record_gcc_switches)
999 Record gcc command line switches in the object file.
1002 Common Report Var(flag_pcc_struct_return,0) VarExists Optimization
1003 Return small aggregates in registers
1006 Common Report Var(flag_regmove) Optimization
1007 Enables a register move optimization
1010 Common Report Var(flag_rename_registers) Init(2) Optimization
1011 Perform a register renaming optimization pass
1014 Common Report Var(flag_reorder_blocks) Optimization
1015 Reorder basic blocks to improve code placement
1017 freorder-blocks-and-partition
1018 Common Report Var(flag_reorder_blocks_and_partition) Optimization
1019 Reorder basic blocks and partition into hot and cold sections
1022 Common Report Var(flag_reorder_functions) Optimization
1023 Reorder functions to improve code placement
1025 frerun-cse-after-loop
1026 Common Report Var(flag_rerun_cse_after_loop) Init(2) Optimization
1027 Add a common subexpression elimination pass after loop optimizations
1031 Does nothing. Preserved for backward compatibility.
1034 Common Report Var(flag_rounding_math) Optimization
1035 Disable optimizations that assume default FP rounding behavior
1038 Common Report Var(flag_schedule_interblock) Init(1) Optimization
1039 Enable scheduling across basic blocks
1042 Common Report Var(flag_sched_pressure) Init(0) Optimization
1043 Enable register pressure sensitive insn scheduling
1046 Common Report Var(flag_schedule_speculative) Init(1) Optimization
1047 Allow speculative motion of non-loads
1050 Common Report Var(flag_schedule_speculative_load) Optimization
1051 Allow speculative motion of some loads
1053 fsched-spec-load-dangerous
1054 Common Report Var(flag_schedule_speculative_load_dangerous) Optimization
1055 Allow speculative motion of more loads
1058 Common RejectNegative Joined
1059 -fsched-verbose=<number> Set the verbosity level of the scheduler
1061 fsched2-use-superblocks
1062 Common Report Var(flag_sched2_use_superblocks) Optimization
1063 If scheduling post reload, do superblock scheduling
1067 Does nothing. Preserved for backward compatibility.
1070 Common Report Var(flag_schedule_insns) Optimization
1071 Reschedule instructions before register allocation
1074 Common Report Var(flag_schedule_insns_after_reload) Optimization
1075 Reschedule instructions after register allocation
1077 ; This flag should be on when a target implements non-trivial
1078 ; scheduling hooks, maybe saving some information for its own sake.
1079 ; On IA64, for example, this is used for correct bundling.
1080 fselective-scheduling
1081 Common Report Var(flag_selective_scheduling) Optimization
1082 Schedule instructions using selective scheduling algorithm
1084 fselective-scheduling2
1085 Common Report Var(flag_selective_scheduling2) Optimization
1086 Run selective scheduling after reload
1088 fsel-sched-pipelining
1089 Common Report Var(flag_sel_sched_pipelining) Init(0) Optimization
1090 Perform software pipelining of inner loops during selective scheduling
1092 fsel-sched-pipelining-outer-loops
1093 Common Report Var(flag_sel_sched_pipelining_outer_loops) Init(0) Optimization
1094 Perform software pipelining of outer loops during selective scheduling
1096 fsel-sched-reschedule-pipelined
1097 Common Report Var(flag_sel_sched_reschedule_pipelined) Init(0) Optimization
1098 Reschedule pipelined regions without pipelining
1100 ; sched_stalled_insns means that insns can be moved prematurely from the queue
1101 ; of stalled insns into the ready list.
1102 fsched-stalled-insns
1103 Common Report Var(flag_sched_stalled_insns) Optimization UInteger
1104 Allow premature scheduling of queued insns
1106 fsched-stalled-insns=
1107 Common RejectNegative Joined UInteger
1108 -fsched-stalled-insns=<number> Set number of queued insns that can be prematurely scheduled
1110 ; sched_stalled_insns_dep controls how many recently scheduled cycles will
1111 ; be examined for a dependency on a stalled insn that is candidate for
1112 ; premature removal from the queue of stalled insns into the ready list (has
1113 ; an effect only if the flag 'sched_stalled_insns' is set).
1114 fsched-stalled-insns-dep
1115 Common Report Var(flag_sched_stalled_insns_dep,1) Init(1) Optimization UInteger
1116 Set dependence distance checking in premature scheduling of queued insns
1118 fsched-stalled-insns-dep=
1119 Common RejectNegative Joined UInteger
1120 -fsched-stalled-insns-dep=<number> Set dependence distance checking in premature scheduling of queued insns
1122 fsched-group-heuristic
1123 Common Report Var(flag_sched_group_heuristic) Init(1) Optimization
1124 Enable the group heuristic in the scheduler
1126 fsched-critical-path-heuristic
1127 Common Report Var(flag_sched_critical_path_heuristic) Init(1) Optimization
1128 Enable the critical path heuristic in the scheduler
1130 fsched-spec-insn-heuristic
1131 Common Report Var(flag_sched_spec_insn_heuristic) Init(1) Optimization
1132 Enable the speculative instruction heuristic in the scheduler
1134 fsched-rank-heuristic
1135 Common Report Var(flag_sched_rank_heuristic) Init(1) Optimization
1136 Enable the rank heuristic in the scheduler
1138 fsched-last-insn-heuristic
1139 Common Report Var(flag_sched_last_insn_heuristic) Init(1) Optimization
1140 Enable the last instruction heuristic in the scheduler
1142 fsched-dep-count-heuristic
1143 Common Report Var(flag_sched_dep_count_heuristic) Init(1) Optimization
1144 Enable the dependent count heuristic in the scheduler
1147 Common Report Var(flag_section_anchors) Optimization
1148 Access data in the same section from shared anchor points
1152 Does nothing. Preserved for backward compatibility.
1155 Common Report Var(flag_zee) Init(0)
1156 Eliminate redundant zero extensions on targets that support implicit extensions.
1159 Common Report Var(flag_show_column) Init(1)
1160 Show column numbers in diagnostics, when available. Default on
1163 Common Report Var(flag_signaling_nans) Optimization
1164 Disable optimizations observable by IEEE signaling NaNs
1167 Common Report Var(flag_signed_zeros) Init(1) Optimization
1168 Disable floating point optimizations that ignore the IEEE signedness of zero
1170 fsingle-precision-constant
1171 Common Report Var(flag_single_precision_constant) Optimization
1172 Convert floating point constants to single precision constants
1174 fsplit-ivs-in-unroller
1175 Common Report Var(flag_split_ivs_in_unroller) Init(1) Optimization
1176 Split lifetimes of induction variables when loops are unrolled
1179 Common Report Var(flag_split_wide_types) Optimization
1180 Split wide types into independent registers
1182 fvariable-expansion-in-unroller
1183 Common Report Var(flag_variable_expansion_in_unroller) Optimization
1184 Apply variable expansion when loops are unrolled
1187 Common Report RejectNegative Joined
1188 -fstack-check=[no|generic|specific] Insert stack checking code into the program
1192 Insert stack checking code into the program. Same as -fstack-check=specific
1197 fstack-limit-register=
1198 Common RejectNegative Joined
1199 -fstack-limit-register=<register> Trap if the stack goes past <register>
1201 fstack-limit-symbol=
1202 Common RejectNegative Joined
1203 -fstack-limit-symbol=<name> Trap if the stack goes past symbol <name>
1206 Common Report Var(flag_stack_protect, 1)
1207 Use propolice as a stack protection method
1209 fstack-protector-all
1210 Common Report RejectNegative Var(flag_stack_protect, 2) VarExists
1211 Use a stack protection method for every function
1215 Does nothing. Preserved for backward compatibility.
1217 ; Nonzero if we should do (language-dependent) alias analysis.
1218 ; Typically, this analysis will assume that expressions of certain
1219 ; types do not alias expressions of certain other types. Only used
1220 ; if alias analysis (in general) is enabled.
1222 Common Report Var(flag_strict_aliasing) Optimization
1223 Assume strict aliasing rules apply
1226 Common Report Var(flag_strict_overflow)
1227 Treat signed overflow as undefined
1230 Common Report Var(flag_syntax_only)
1231 Check for syntax errors, then stop
1234 Common Report Var(flag_test_coverage)
1235 Create data files needed by \"gcov\"
1238 Common Report Var(flag_thread_jumps) Optimization
1239 Perform jump threading optimizations
1242 Common Report Var(time_report)
1243 Report the time taken by each compiler pass
1246 Common Joined RejectNegative
1247 -ftls-model=[global-dynamic|local-dynamic|initial-exec|local-exec] Set the default thread-local storage code generation model
1250 Common Report Var(flag_toplevel_reorder) Init(2) Optimization
1251 Reorder top level functions, variables, and asms
1254 Common Report Var(flag_tracer)
1255 Perform superblock formation via tail duplication
1257 ; Zero means that floating-point math operations cannot generate a
1258 ; (user-visible) trap. This is the case, for example, in nonstop
1259 ; IEEE 754 arithmetic.
1261 Common Report Var(flag_trapping_math) Init(1) Optimization
1262 Assume floating-point operations can trap
1265 Common Report Var(flag_trapv) Optimization
1266 Trap for signed overflow in addition, subtraction and multiplication
1269 Common Report Var(flag_tree_ccp) Optimization
1270 Enable SSA-CCP optimization on trees
1274 Does nothing. Preserved for backward compatibility.
1277 Common Report Var(flag_tree_ch) Optimization
1278 Enable loop header copying on trees
1281 Common Report Var(flag_tree_copyrename) Optimization
1282 Replace SSA temporaries with better names in copies
1285 Common Report Var(flag_tree_copy_prop) Optimization
1286 Enable copy propagation on trees
1288 ftree-store-copy-prop
1290 Does nothing. Preserved for backward compatibility.
1293 Common Report Var(flag_tree_cselim) Init(2) Optimization
1294 Transform condition stores into unconditional ones
1296 ftree-switch-conversion
1297 Common Report Var(flag_tree_switch_conversion) Optimization
1298 Perform conversions of switch initializations.
1301 Common Report Var(flag_tree_dce) Optimization
1302 Enable SSA dead code elimination optimization on trees
1304 ftree-dominator-opts
1305 Common Report Var(flag_tree_dom) Optimization
1306 Enable dominator optimizations
1309 Common Report Var(flag_tree_dse) Optimization
1310 Enable dead store elimination
1313 Common Report Var(flag_tree_forwprop) Init(1) Optimization
1314 Enable forward propagation on trees
1317 Common Report Var(flag_tree_fre) Optimization
1318 Enable Full Redundancy Elimination (FRE) on trees
1320 ftree-loop-distribution
1321 Common Report Var(flag_tree_loop_distribution) Optimization
1322 Enable loop distribution on trees
1325 Common Report Var(flag_tree_loop_im) Init(1) Optimization
1326 Enable loop invariant motion on trees
1329 Common Report Var(flag_tree_loop_linear) Optimization
1330 Enable linear loop transforms on trees
1333 Common Report Var(flag_tree_loop_ivcanon) Init(1) Optimization
1334 Create canonical induction variables in loops
1337 Common Report Var(flag_tree_loop_optimize) Init(1) Optimization
1338 Enable loop optimizations on tree level
1340 ftree-parallelize-loops=
1341 Common Report Joined UInteger Var(flag_tree_parallelize_loops) Init(1)
1342 Enable automatic parallelization of loops
1345 Common Report Var(flag_tree_phiprop) Init(1) Optimization
1346 Enable hoisting loads from conditional pointers.
1349 Common Report Var(flag_tree_pre) Optimization
1350 Enable SSA-PRE optimization on trees
1353 Common Report Var(flag_tree_pta) Init(1) Optimization
1354 Perform function-local points-to analysis on trees.
1357 Common Report Var(flag_tree_reassoc) Init(1) Optimization
1358 Enable reassociation on tree level
1362 Does nothing. Preserved for backward compatibility.
1365 Common Report Var(flag_tree_sink) Optimization
1366 Enable SSA code sinking on trees
1369 Common Report Var(flag_tree_sra) Optimization
1370 Perform scalar replacement of aggregates
1373 Common Report Var(flag_tree_ter) Init(1) Optimization
1374 Replace temporary expressions in the SSA->normal pass
1377 Common Report Var(flag_tree_live_range_split) Optimization
1378 Perform live range splitting during the SSA->normal pass
1381 Common Report Var(flag_tree_vrp) Init(0) Optimization
1382 Perform Value Range Propagation on trees
1385 Common Report Var(flag_unit_at_a_time) Init(1) Optimization
1386 Compile whole compilation unit at a time
1389 Common Report Var(flag_unroll_loops) Optimization
1390 Perform loop unrolling when iteration count is known
1393 Common Report Var(flag_unroll_all_loops) Optimization
1394 Perform loop unrolling for all loops
1396 ; Nonzero means that loop optimizer may assume that the induction variables
1397 ; that control loops do not overflow and that the loops with nontrivial
1398 ; exit condition are not infinite
1399 funsafe-loop-optimizations
1400 Common Report Var(flag_unsafe_loop_optimizations) Optimization
1401 Allow loop optimizations to assume that the loops behave in normal way
1404 Common Report Var(flag_associative_math)
1405 Allow optimization for floating-point arithmetic which may change the
1406 result of the operation due to rounding.
1409 Common Report Var(flag_reciprocal_math)
1410 Same as -fassociative-math for expressions which include division.
1412 ; Nonzero means that unsafe floating-point math optimizations are allowed
1413 ; for the sake of speed. IEEE compliance is not guaranteed, and operations
1414 ; are allowed to assume that their arguments and results are "normal"
1415 ; (e.g., nonnegative for SQRT).
1416 funsafe-math-optimizations
1417 Common Report Var(flag_unsafe_math_optimizations) Optimization
1418 Allow math optimizations that may violate IEEE or ISO standards
1421 Common Report Var(flag_unswitch_loops) Optimization
1422 Perform loop unswitching
1425 Common Report Var(flag_unwind_tables) Optimization
1426 Just generate unwind tables for exception handling
1432 Common Report Var(flag_var_tracking) VarExists Optimization
1433 Perform variable tracking
1435 fvar-tracking-assignments
1436 Common Report Var(flag_var_tracking_assignments) VarExists Optimization
1437 Perform variable tracking by annotating assignments
1439 fvar-tracking-assignments-toggle
1440 Common Report Var(flag_var_tracking_assignments_toggle) VarExists Optimization
1441 Toggle -fvar-tracking-assignments
1443 fvar-tracking-uninit
1444 Common Report Var(flag_var_tracking_uninit) Optimization
1445 Perform variable tracking and also tag variables that are uninitialized
1448 Common Report Var(flag_tree_vectorize) Optimization
1449 Enable loop vectorization on trees
1452 Common Report Var(flag_tree_slp_vectorize) Init(2) Optimization
1453 Enable basic block vectorization (SLP) on trees
1456 Common Report Var(flag_vect_cost_model) Optimization
1457 Enable use of cost model in vectorization
1459 ftree-vect-loop-version
1460 Common Report Var(flag_tree_vect_loop_version) Init(1) Optimization
1461 Enable loop versioning when doing loop vectorization on trees
1463 ftree-vectorizer-verbose=
1464 Common RejectNegative Joined
1465 -ftree-vectorizer-verbose=<number> Set the verbosity level of the vectorizer
1468 Common Report Var(flag_tree_scev_cprop) Init(1) Optimization
1469 Enable copy propagation of scalar-evolution information.
1471 ; -fverbose-asm causes extra commentary information to be produced in
1472 ; the generated assembly code (to make it more readable). This option
1473 ; is generally only of use to those who actually need to read the
1474 ; generated assembly code (perhaps while debugging the compiler itself).
1475 ; -fno-verbose-asm, the default, causes the extra information
1476 ; to not be added and is useful when comparing two assembler files.
1478 Common Report Var(flag_verbose_asm)
1479 Add extra commentary to assembler output
1482 Common Joined RejectNegative
1483 -fvisibility=[default|internal|hidden|protected] Set the default symbol visibility
1487 Common Report Var(flag_value_profile_transformations) Optimization
1488 Use expression value profiles in optimizations
1491 Common Report Var(flag_web) Init(2) Optimization
1492 Construct webs and split unrelated uses of single variable
1496 Enable partitioned link-time optimization
1499 Common RejectNegative UInteger Joined Var(flag_whopr)
1500 Enable partitioned link-time optimization with specified number of parallel jobs
1502 ftree-builtin-call-dce
1503 Common Report Var(flag_tree_builtin_call_dce) Init(0) Optimization
1504 Enable conditional dead code elimination for builtin calls
1507 Common Report Var(flag_whole_program) Init(0) Optimization
1508 Perform whole program optimizations
1511 Common Report Var(flag_wrapv) Optimization
1512 Assume signed arithmetic overflow wraps around
1514 fzero-initialized-in-bss
1515 Common Report Var(flag_zero_initialized_in_bss) Init(1)
1516 Put zero initialized data in the bss section
1519 Common JoinedOrMissing
1520 Generate debug information in default format
1523 Common JoinedOrMissing Negative(gdwarf-)
1524 Generate debug information in COFF format
1527 Common Joined UInteger Var(dwarf_version) Init(2) Negative(gstabs)
1528 Generate debug information in DWARF v2 (or later) format
1531 Common JoinedOrMissing
1532 Generate debug information in default extended format
1535 Common JoinedOrMissing Negative(gstabs+)
1536 Generate debug information in STABS format
1539 Common JoinedOrMissing Negative(gvms)
1540 Generate debug information in extended STABS format
1543 Common RejectNegative Var(dwarf_strict,0) Init(-1)
1544 Emit DWARF additions beyond selected version
1547 Common Report RejectNegative Var(dwarf_strict,1) VarExists
1548 Don't emit DWARF additions beyond selected version
1551 Common Report Var(flag_gtoggle)
1552 Toggle debug information generation
1555 Common JoinedOrMissing Negative(gxcoff)
1556 Generate debug information in VMS format
1559 Common JoinedOrMissing Negative(gxcoff+)
1560 Generate debug information in XCOFF format
1563 Common JoinedOrMissing Negative(gcoff)
1564 Generate debug information in extended XCOFF format
1567 Common Joined Var(plugindir_string) Init(0)
1568 -iplugindir=<dir> Set <dir> to be the default plugin directory
1571 Common Joined Separate
1572 -o <file> Place output into <file>
1575 Common Var(profile_flag)
1576 Enable function profiling
1579 Common Var(pedantic)
1580 Issue warnings needed for strict compliance to the standard
1584 Like -pedantic but issue them as errors
1587 Common Var(quiet_flag)
1588 Do not display functions compiled or elapsed time
1591 Common Var(version_flag)
1592 Display the compiler's version
1595 Common Var(inhibit_warnings)
1599 Common RejectNegative Negative(pie)
1600 Create a shared library
1603 Common RejectNegative Negative(shared)
1604 Create a position independent executable
1606 ; This comment is to ensure we retain the blank line above.