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 RejectNegative 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 RejectNegative 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 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 ; -finhibit-size-directive inhibits output of .size for ELF.
657 ; This is used only for compiling crtstuff.c,
658 ; and it may be extended to other effects
659 ; needed for crtstuff.c on other systems.
660 finhibit-size-directive
661 Common Report Var(flag_inhibit_size_directive)
662 Do not generate .size directives
665 Common Report Var(flag_indirect_inlining)
666 Perform indirect inlining
668 ; Nonzero means that functions declared `inline' will be treated
669 ; as `static'. Prevents generation of zillions of copies of unused
670 ; static inline functions; instead, `inlines' are written out
671 ; only when actually used. Used in conjunction with -g. Also
672 ; does the right thing with #pragma interface.
674 Common Report Var(flag_no_inline,0) Init(0)
675 Pay attention to the \"inline\" keyword
677 finline-small-functions
678 Common Report Var(flag_inline_small_functions) Optimization
679 Integrate simple functions into their callers when code size is known to not growth
682 Common Report Var(flag_inline_functions) Optimization
683 Integrate simple functions into their callers
685 finline-functions-called-once
686 Common Report Var(flag_inline_functions_called_once) Init(1) Optimization
687 Integrate functions called once into their callers
690 Common RejectNegative Joined UInteger
693 Common RejectNegative Joined UInteger
694 -finline-limit=<number> Limit the size of inlined functions to <number>
696 finstrument-functions
697 Common Report Var(flag_instrument_function_entry_exit)
698 Instrument function entry and exit with profiling calls
700 finstrument-functions-exclude-function-list=
701 Common RejectNegative Joined
702 -finstrument-functions-exclude-function-list=name,... Do not instrument listed functions
704 finstrument-functions-exclude-file-list=
705 Common RejectNegative Joined
706 -finstrument-functions-exclude-file-list=filename,... Do not instrument functions listed in files
709 Common Report Var(flag_ipa_cp) Optimization
710 Perform Interprocedural constant propagation
713 Common Report Var(flag_ipa_cp_clone) Optimization
714 Perform cloning to make Interprocedural constant propagation stronger
717 Common Report Var(flag_ipa_profile) Init(0) Optimization
718 Perform interprocedural profile propagation
721 Common Report Var(flag_ipa_pta) Init(0) Optimization
722 Perform interprocedural points-to analysis
725 Common Report Var(flag_ipa_pure_const) Init(0) Optimization
726 Discover pure and const functions
729 Common Report Var(flag_ipa_reference) Init(0) Optimization
730 Discover readonly and non addressable static variables
733 Common Report Var(flag_ipa_matrix_reorg) Optimization
734 Perform matrix layout flattening and transposing based
735 on profiling information.
738 Common Report Var(flag_ipa_struct_reorg)
739 Perform structure layout optimizations based
740 on profiling information.
743 Common Joined RejectNegative
744 -fira-algorithm=[CB|priority] Set the used IRA algorithm
747 Common Joined RejectNegative
748 -fira-region=[one|all|mixed] Set regions for IRA
751 Common Report Var(flag_ira_coalesce) Init(0)
752 Do optimistic coalescing.
755 Common Report Var(flag_ira_loop_pressure)
756 Use IRA based register pressure calculation
757 in RTL loop optimizations.
759 fira-share-save-slots
760 Common Report Var(flag_ira_share_save_slots) Init(1)
761 Share slots for saving different hard registers.
763 fira-share-spill-slots
764 Common Report Var(flag_ira_share_spill_slots) Init(1)
765 Share stack slots for spilled pseudo-registers.
768 Common RejectNegative Joined UInteger Var(flag_ira_verbose) Init(5)
769 -fira-verbose=<number> Control IRA's level of diagnostic messages.
772 Common Report Var(flag_ivopts) Init(1) Optimization
773 Optimize induction variables on trees
776 Common Var(flag_jump_tables) Init(1) Optimization
777 Use jump tables for sufficiently large switch statements
779 fkeep-inline-functions
780 Common Report Var(flag_keep_inline_functions)
781 Generate code for functions even if they are fully inlined
784 Common Report Var(flag_keep_static_consts) Init(1)
785 Emit static const variables even if they are not used
788 Common Report Var(flag_leading_underscore) Init(-1)
789 Give external symbols a leading underscore
793 Does nothing. Preserved for backward compatibility.
797 Enable link-time optimization.
799 ; The initial value of -1 comes from Z_DEFAULT_COMPRESSION in zlib.h.
800 flto-compression-level=
801 Common Joined RejectNegative UInteger Var(flag_lto_compression_level) Init(-1)
802 -flto-compression-level=<number> Use zlib compression level <number> for IL
805 Common Report Var(flag_lto_report) Init(0) Optimization
806 Report various link-time optimization statistics
809 Common Report Var(flag_errno_math) Init(1) Optimization
810 Set errno after built-in math functions
813 Common Report Var(mem_report)
814 Report on permanent memory allocation
816 ; This will attempt to merge constant section constants, if 1 only
817 ; string constants and constants from constant pool, if 2 also constant
820 Common Report Var(flag_merge_constants,2) Init(1) Optimization
821 Attempt to merge identical constants and constant variables
824 Common Report Var(flag_merge_constants,1) VarExists Optimization
825 Attempt to merge identical constants across compilation units
828 Common Report Var(flag_merge_debug_strings) Init(1)
829 Attempt to merge identical debug strings across compilation units
832 Common RejectNegative Joined UInteger
833 -fmessage-length=<number> Limit diagnostics to <number> characters per line. 0 suppresses line-wrapping
836 Common Report Var(flag_modulo_sched) Optimization
837 Perform SMS based modulo scheduling before the first scheduling pass
839 fmodulo-sched-allow-regmoves
840 Common Report Var(flag_modulo_sched_allow_regmoves)
841 Perform SMS based modulo scheduling with register moves allowed
843 fmove-loop-invariants
844 Common Report Var(flag_move_loop_invariants) Init(1) Optimization
845 Move loop invariant computations out of loops
848 Common RejectNegative Report Var(flag_mudflap)
849 Add mudflap bounds-checking instrumentation for single-threaded program
852 Common RejectNegative Report VarExists Var(flag_mudflap,2)
853 Add mudflap bounds-checking instrumentation for multi-threaded program
856 Common RejectNegative Report Var(flag_mudflap_ignore_reads)
857 Ignore read operations when inserting mudflap instrumentation
860 Common Var(flag_dce) Init(1) Optimization
861 Use the RTL dead code elimination pass
864 Common Var(flag_dse) Init(1) Optimization
865 Use the RTL dead store elimination pass
867 freschedule-modulo-scheduled-loops
868 Common Report Var(flag_resched_modulo_sched) Optimization
869 Enable/Disable the traditional scheduling in loops that already passed modulo scheduling
872 Common Report Var(flag_non_call_exceptions) Optimization
873 Support synchronous non-call exceptions
876 Common Report Var(flag_omit_frame_pointer) Optimization
877 When possible do not generate stack frames
879 foptimize-register-move
880 Common Report Var(flag_regmove) Optimization
881 Do the full register move optimization pass
883 foptimize-sibling-calls
884 Common Report Var(flag_optimize_sibling_calls) Optimization
885 Optimize sibling and tail recursive calls
888 Common Report Var(flag_partial_inlining)
889 Perform partial inlining
892 Common Report Var(pre_ipa_mem_report)
893 Report on memory allocation before interprocedural optimization
896 Common Report Var(post_ipa_mem_report)
897 Report on memory allocation before interprocedural optimization
900 Common Report Var(flag_pack_struct) Optimization
901 Pack structure members together without holes
904 Common RejectNegative Joined UInteger Optimization
905 -fpack-struct=<number> Set initial maximum structure member alignment
908 Common Report Var(flag_pcc_struct_return,1) Init(DEFAULT_PCC_STRUCT_RETURN)
909 Return small aggregates in memory, not registers
912 Common Report Var(flag_peel_loops) Optimization
916 Common Report Var(flag_no_peephole,0) Optimization
917 Enable machine specific peephole optimizations
920 Common Report Var(flag_peephole2) Optimization
921 Enable an RTL peephole pass before sched2
924 Common Report Var(flag_pic,2)
925 Generate position-independent code if possible (large mode)
928 Common Report Var(flag_pie,2)
929 Generate position-independent code for executables if possible (large mode)
932 Common Report Var(flag_pic,1) VarExists
933 Generate position-independent code if possible (small mode)
936 Common Report Var(flag_pie,1) VarExists
937 Generate position-independent code for executables if possible (small mode)
940 Common Joined RejectNegative
941 Specify a plugin to load
944 Common Joined RejectNegative
945 -fplugin-arg-<name>-<key>[=<value>] Specify argument <key>=<value> for plugin <name>
947 fpredictive-commoning
948 Common Report Var(flag_predictive_commoning) Optimization
949 Run predictive commoning optimization.
951 fprefetch-loop-arrays
952 Common Report Var(flag_prefetch_loop_arrays) Init(-1) Optimization
953 Generate prefetch instructions, if available, for arrays in loops
956 Common Report Var(profile_flag)
957 Enable basic program profiling code
960 Common Report Var(profile_arc_flag)
961 Insert arc-based program profiling code
964 Common Joined RejectNegative
965 Set the top-level directory for storing the profile data.
966 The default is 'pwd'.
969 Common Report Var(flag_profile_correction)
970 Enable correction of flow inconsistent profile data input
974 Enable common options for generating profile info for profile feedback directed optimizations
977 Common Joined RejectNegative
978 Enable common options for generating profile info for profile feedback directed optimizations, and set -fprofile-dir=
981 Common Var(flag_profile_use)
982 Enable common options for performing profile feedback directed optimizations
985 Common Joined RejectNegative
986 Enable common options for performing profile feedback directed optimizations, and set -fprofile-dir=
989 Common Report Var(flag_profile_values)
990 Insert code to profile values of expressions
996 Common Joined RejectNegative
997 -frandom-seed=<string> Make compile reproducible using <string>
999 ; This switch causes the command line that was used to create an
1000 ; object file to be recorded into the object file. The exact format
1001 ; of this recording is target and binary file format dependent.
1002 ; It is related to the -fverbose-asm switch, but that switch only
1003 ; records information in the assembler output file as comments, so
1004 ; they never reach the object file.
1005 frecord-gcc-switches
1006 Common Report Var(flag_record_gcc_switches)
1007 Record gcc command line switches in the object file.
1010 Common Report Var(flag_pcc_struct_return,0) VarExists Optimization
1011 Return small aggregates in registers
1014 Common Report Var(flag_regmove) Optimization
1015 Enables a register move optimization
1018 Common Report Var(flag_rename_registers) Init(2) Optimization
1019 Perform a register renaming optimization pass
1022 Common Report Var(flag_reorder_blocks) Optimization
1023 Reorder basic blocks to improve code placement
1025 freorder-blocks-and-partition
1026 Common Report Var(flag_reorder_blocks_and_partition) Optimization
1027 Reorder basic blocks and partition into hot and cold sections
1030 Common Report Var(flag_reorder_functions) Optimization
1031 Reorder functions to improve code placement
1033 frerun-cse-after-loop
1034 Common Report Var(flag_rerun_cse_after_loop) Init(2) Optimization
1035 Add a common subexpression elimination pass after loop optimizations
1039 Does nothing. Preserved for backward compatibility.
1042 Common Report Var(flag_rounding_math) Optimization
1043 Disable optimizations that assume default FP rounding behavior
1046 Common Report Var(flag_schedule_interblock) Init(1) Optimization
1047 Enable scheduling across basic blocks
1050 Common Report Var(flag_sched_pressure) Init(0) Optimization
1051 Enable register pressure sensitive insn scheduling
1054 Common Report Var(flag_schedule_speculative) Init(1) Optimization
1055 Allow speculative motion of non-loads
1058 Common Report Var(flag_schedule_speculative_load) Optimization
1059 Allow speculative motion of some loads
1061 fsched-spec-load-dangerous
1062 Common Report Var(flag_schedule_speculative_load_dangerous) Optimization
1063 Allow speculative motion of more loads
1066 Common RejectNegative Joined
1067 -fsched-verbose=<number> Set the verbosity level of the scheduler
1069 fsched2-use-superblocks
1070 Common Report Var(flag_sched2_use_superblocks) Optimization
1071 If scheduling post reload, do superblock scheduling
1075 Does nothing. Preserved for backward compatibility.
1078 Common Report Var(flag_schedule_insns) Optimization
1079 Reschedule instructions before register allocation
1082 Common Report Var(flag_schedule_insns_after_reload) Optimization
1083 Reschedule instructions after register allocation
1085 ; This flag should be on when a target implements non-trivial
1086 ; scheduling hooks, maybe saving some information for its own sake.
1087 ; On IA64, for example, this is used for correct bundling.
1088 fselective-scheduling
1089 Common Report Var(flag_selective_scheduling) Optimization
1090 Schedule instructions using selective scheduling algorithm
1092 fselective-scheduling2
1093 Common Report Var(flag_selective_scheduling2) Optimization
1094 Run selective scheduling after reload
1096 fsel-sched-pipelining
1097 Common Report Var(flag_sel_sched_pipelining) Init(0) Optimization
1098 Perform software pipelining of inner loops during selective scheduling
1100 fsel-sched-pipelining-outer-loops
1101 Common Report Var(flag_sel_sched_pipelining_outer_loops) Init(0) Optimization
1102 Perform software pipelining of outer loops during selective scheduling
1104 fsel-sched-reschedule-pipelined
1105 Common Report Var(flag_sel_sched_reschedule_pipelined) Init(0) Optimization
1106 Reschedule pipelined regions without pipelining
1108 ; sched_stalled_insns means that insns can be moved prematurely from the queue
1109 ; of stalled insns into the ready list.
1110 fsched-stalled-insns
1111 Common Report Var(flag_sched_stalled_insns) Optimization UInteger
1112 Allow premature scheduling of queued insns
1114 fsched-stalled-insns=
1115 Common RejectNegative Joined UInteger
1116 -fsched-stalled-insns=<number> Set number of queued insns that can be prematurely scheduled
1118 ; sched_stalled_insns_dep controls how many recently scheduled cycles will
1119 ; be examined for a dependency on a stalled insn that is candidate for
1120 ; premature removal from the queue of stalled insns into the ready list (has
1121 ; an effect only if the flag 'sched_stalled_insns' is set).
1122 fsched-stalled-insns-dep
1123 Common Report Var(flag_sched_stalled_insns_dep,1) Init(1) Optimization UInteger
1124 Set dependence distance checking in premature scheduling of queued insns
1126 fsched-stalled-insns-dep=
1127 Common RejectNegative Joined UInteger
1128 -fsched-stalled-insns-dep=<number> Set dependence distance checking in premature scheduling of queued insns
1130 fsched-group-heuristic
1131 Common Report Var(flag_sched_group_heuristic) Init(1) Optimization
1132 Enable the group heuristic in the scheduler
1134 fsched-critical-path-heuristic
1135 Common Report Var(flag_sched_critical_path_heuristic) Init(1) Optimization
1136 Enable the critical path heuristic in the scheduler
1138 fsched-spec-insn-heuristic
1139 Common Report Var(flag_sched_spec_insn_heuristic) Init(1) Optimization
1140 Enable the speculative instruction heuristic in the scheduler
1142 fsched-rank-heuristic
1143 Common Report Var(flag_sched_rank_heuristic) Init(1) Optimization
1144 Enable the rank heuristic in the scheduler
1146 fsched-last-insn-heuristic
1147 Common Report Var(flag_sched_last_insn_heuristic) Init(1) Optimization
1148 Enable the last instruction heuristic in the scheduler
1150 fsched-dep-count-heuristic
1151 Common Report Var(flag_sched_dep_count_heuristic) Init(1) Optimization
1152 Enable the dependent count heuristic in the scheduler
1155 Common Report Var(flag_section_anchors) Optimization
1156 Access data in the same section from shared anchor points
1160 Does nothing. Preserved for backward compatibility.
1163 Common Report Var(flag_zee) Init(0)
1164 Eliminate redundant zero extensions on targets that support implicit extensions.
1167 Common Report Var(flag_show_column) Init(1)
1168 Show column numbers in diagnostics, when available. Default on
1171 Common Report Var(flag_signaling_nans) Optimization
1172 Disable optimizations observable by IEEE signaling NaNs
1175 Common Report Var(flag_signed_zeros) Init(1) Optimization
1176 Disable floating point optimizations that ignore the IEEE signedness of zero
1178 fsingle-precision-constant
1179 Common Report Var(flag_single_precision_constant) Optimization
1180 Convert floating point constants to single precision constants
1182 fsplit-ivs-in-unroller
1183 Common Report Var(flag_split_ivs_in_unroller) Init(1) Optimization
1184 Split lifetimes of induction variables when loops are unrolled
1187 Common Report Var(flag_split_wide_types) Optimization
1188 Split wide types into independent registers
1190 fvariable-expansion-in-unroller
1191 Common Report Var(flag_variable_expansion_in_unroller) Optimization
1192 Apply variable expansion when loops are unrolled
1195 Common Report RejectNegative Joined
1196 -fstack-check=[no|generic|specific] Insert stack checking code into the program
1200 Insert stack checking code into the program. Same as -fstack-check=specific
1205 fstack-limit-register=
1206 Common RejectNegative Joined
1207 -fstack-limit-register=<register> Trap if the stack goes past <register>
1209 fstack-limit-symbol=
1210 Common RejectNegative Joined
1211 -fstack-limit-symbol=<name> Trap if the stack goes past symbol <name>
1214 Common Report Var(flag_stack_protect, 1)
1215 Use propolice as a stack protection method
1217 fstack-protector-all
1218 Common Report RejectNegative Var(flag_stack_protect, 2) VarExists
1219 Use a stack protection method for every function
1223 Does nothing. Preserved for backward compatibility.
1225 ; Nonzero if we should do (language-dependent) alias analysis.
1226 ; Typically, this analysis will assume that expressions of certain
1227 ; types do not alias expressions of certain other types. Only used
1228 ; if alias analysis (in general) is enabled.
1230 Common Report Var(flag_strict_aliasing) Optimization
1231 Assume strict aliasing rules apply
1234 Common Report Var(flag_strict_overflow)
1235 Treat signed overflow as undefined
1238 Common Report Var(flag_syntax_only)
1239 Check for syntax errors, then stop
1242 Common Report Var(flag_test_coverage)
1243 Create data files needed by \"gcov\"
1246 Common Report Var(flag_thread_jumps) Optimization
1247 Perform jump threading optimizations
1250 Common Report Var(time_report)
1251 Report the time taken by each compiler pass
1254 Common Joined RejectNegative
1255 -ftls-model=[global-dynamic|local-dynamic|initial-exec|local-exec] Set the default thread-local storage code generation model
1258 Common Report Var(flag_toplevel_reorder) Init(2) Optimization
1259 Reorder top level functions, variables, and asms
1262 Common Report Var(flag_tracer)
1263 Perform superblock formation via tail duplication
1265 ; Zero means that floating-point math operations cannot generate a
1266 ; (user-visible) trap. This is the case, for example, in nonstop
1267 ; IEEE 754 arithmetic.
1269 Common Report Var(flag_trapping_math) Init(1) Optimization
1270 Assume floating-point operations can trap
1273 Common Report Var(flag_trapv) Optimization
1274 Trap for signed overflow in addition, subtraction and multiplication
1277 Common Report Var(flag_tree_ccp) Optimization
1278 Enable SSA-CCP optimization on trees
1282 Does nothing. Preserved for backward compatibility.
1285 Common Report Var(flag_tree_ch) Optimization
1286 Enable loop header copying on trees
1289 Common Report Var(flag_tree_copyrename) Optimization
1290 Replace SSA temporaries with better names in copies
1293 Common Report Var(flag_tree_copy_prop) Optimization
1294 Enable copy propagation on trees
1296 ftree-store-copy-prop
1298 Does nothing. Preserved for backward compatibility.
1301 Common Report Var(flag_tree_cselim) Init(2) Optimization
1302 Transform condition stores into unconditional ones
1304 ftree-switch-conversion
1305 Common Report Var(flag_tree_switch_conversion) Optimization
1306 Perform conversions of switch initializations.
1309 Common Report Var(flag_tree_dce) Optimization
1310 Enable SSA dead code elimination optimization on trees
1312 ftree-dominator-opts
1313 Common Report Var(flag_tree_dom) Optimization
1314 Enable dominator optimizations
1317 Common Report Var(flag_tree_dse) Optimization
1318 Enable dead store elimination
1321 Common Report Var(flag_tree_forwprop) Init(1) Optimization
1322 Enable forward propagation on trees
1325 Common Report Var(flag_tree_fre) Optimization
1326 Enable Full Redundancy Elimination (FRE) on trees
1328 ftree-loop-distribution
1329 Common Report Var(flag_tree_loop_distribution) Optimization
1330 Enable loop distribution on trees
1333 Common Report Var(flag_tree_loop_im) Init(1) Optimization
1334 Enable loop invariant motion on trees
1337 Common Report Var(flag_tree_loop_linear) Optimization
1338 Enable linear loop transforms on trees
1341 Common Report Var(flag_tree_loop_ivcanon) Init(1) Optimization
1342 Create canonical induction variables in loops
1345 Common Report Var(flag_tree_loop_optimize) Init(1) Optimization
1346 Enable loop optimizations on tree level
1348 ftree-parallelize-loops=
1349 Common Report Joined RejectNegative UInteger Var(flag_tree_parallelize_loops) Init(1)
1350 Enable automatic parallelization of loops
1353 Common Report Var(flag_tree_phiprop) Init(1) Optimization
1354 Enable hoisting loads from conditional pointers.
1357 Common Report Var(flag_tree_pre) Optimization
1358 Enable SSA-PRE optimization on trees
1361 Common Report Var(flag_tree_pta) Init(1) Optimization
1362 Perform function-local points-to analysis on trees.
1365 Common Report Var(flag_tree_reassoc) Init(1) Optimization
1366 Enable reassociation on tree level
1370 Does nothing. Preserved for backward compatibility.
1373 Common Report Var(flag_tree_sink) Optimization
1374 Enable SSA code sinking on trees
1377 Common Report Var(flag_tree_sra) Optimization
1378 Perform scalar replacement of aggregates
1381 Common Report Var(flag_tree_ter) Init(1) Optimization
1382 Replace temporary expressions in the SSA->normal pass
1385 Common Report Var(flag_tree_live_range_split) Optimization
1386 Perform live range splitting during the SSA->normal pass
1389 Common Report Var(flag_tree_vrp) Init(0) Optimization
1390 Perform Value Range Propagation on trees
1393 Common Report Var(flag_unit_at_a_time) Init(1) Optimization
1394 Compile whole compilation unit at a time
1397 Common Report Var(flag_unroll_loops) Optimization
1398 Perform loop unrolling when iteration count is known
1401 Common Report Var(flag_unroll_all_loops) Optimization
1402 Perform loop unrolling for all loops
1404 ; Nonzero means that loop optimizer may assume that the induction variables
1405 ; that control loops do not overflow and that the loops with nontrivial
1406 ; exit condition are not infinite
1407 funsafe-loop-optimizations
1408 Common Report Var(flag_unsafe_loop_optimizations) Optimization
1409 Allow loop optimizations to assume that the loops behave in normal way
1412 Common Report Var(flag_associative_math)
1413 Allow optimization for floating-point arithmetic which may change the
1414 result of the operation due to rounding.
1417 Common Report Var(flag_reciprocal_math)
1418 Same as -fassociative-math for expressions which include division.
1420 ; Nonzero means that unsafe floating-point math optimizations are allowed
1421 ; for the sake of speed. IEEE compliance is not guaranteed, and operations
1422 ; are allowed to assume that their arguments and results are "normal"
1423 ; (e.g., nonnegative for SQRT).
1424 funsafe-math-optimizations
1425 Common Report Var(flag_unsafe_math_optimizations) Optimization
1426 Allow math optimizations that may violate IEEE or ISO standards
1429 Common Report Var(flag_unswitch_loops) Optimization
1430 Perform loop unswitching
1433 Common Report Var(flag_unwind_tables) Optimization
1434 Just generate unwind tables for exception handling
1440 Common Report Var(flag_var_tracking) VarExists Optimization
1441 Perform variable tracking
1443 fvar-tracking-assignments
1444 Common Report Var(flag_var_tracking_assignments) VarExists Optimization
1445 Perform variable tracking by annotating assignments
1447 fvar-tracking-assignments-toggle
1448 Common Report Var(flag_var_tracking_assignments_toggle) VarExists Optimization
1449 Toggle -fvar-tracking-assignments
1451 fvar-tracking-uninit
1452 Common Report Var(flag_var_tracking_uninit) Optimization
1453 Perform variable tracking and also tag variables that are uninitialized
1456 Common Report Var(flag_tree_vectorize) Optimization
1457 Enable loop vectorization on trees
1460 Common Report Var(flag_tree_slp_vectorize) Init(2) Optimization
1461 Enable basic block vectorization (SLP) on trees
1464 Common Report Var(flag_vect_cost_model) Optimization
1465 Enable use of cost model in vectorization
1467 ftree-vect-loop-version
1468 Common Report Var(flag_tree_vect_loop_version) Init(1) Optimization
1469 Enable loop versioning when doing loop vectorization on trees
1471 ftree-vectorizer-verbose=
1472 Common RejectNegative Joined
1473 -ftree-vectorizer-verbose=<number> Set the verbosity level of the vectorizer
1476 Common Report Var(flag_tree_scev_cprop) Init(1) Optimization
1477 Enable copy propagation of scalar-evolution information.
1479 ; -fverbose-asm causes extra commentary information to be produced in
1480 ; the generated assembly code (to make it more readable). This option
1481 ; is generally only of use to those who actually need to read the
1482 ; generated assembly code (perhaps while debugging the compiler itself).
1483 ; -fno-verbose-asm, the default, causes the extra information
1484 ; to not be added and is useful when comparing two assembler files.
1486 Common Report Var(flag_verbose_asm)
1487 Add extra commentary to assembler output
1490 Common Joined RejectNegative
1491 -fvisibility=[default|internal|hidden|protected] Set the default symbol visibility
1495 Common Report Var(flag_value_profile_transformations) Optimization
1496 Use expression value profiles in optimizations
1499 Common Report Var(flag_web) Init(2) Optimization
1500 Construct webs and split unrelated uses of single variable
1504 Enable partitioned link-time optimization
1507 Common RejectNegative UInteger Joined Var(flag_whopr)
1508 Enable partitioned link-time optimization with specified number of parallel jobs
1510 ftree-builtin-call-dce
1511 Common Report Var(flag_tree_builtin_call_dce) Init(0) Optimization
1512 Enable conditional dead code elimination for builtin calls
1515 Common Report Var(flag_whole_program) Init(0) Optimization
1516 Perform whole program optimizations
1519 Common Report Var(flag_wrapv) Optimization
1520 Assume signed arithmetic overflow wraps around
1522 fzero-initialized-in-bss
1523 Common Report Var(flag_zero_initialized_in_bss) Init(1)
1524 Put zero initialized data in the bss section
1527 Common JoinedOrMissing
1528 Generate debug information in default format
1531 Common JoinedOrMissing Negative(gdwarf-)
1532 Generate debug information in COFF format
1535 Common Joined UInteger Var(dwarf_version) Init(2) Negative(gstabs)
1536 Generate debug information in DWARF v2 (or later) format
1539 Common JoinedOrMissing
1540 Generate debug information in default extended format
1543 Common JoinedOrMissing Negative(gstabs+)
1544 Generate debug information in STABS format
1547 Common JoinedOrMissing Negative(gvms)
1548 Generate debug information in extended STABS format
1551 Common RejectNegative Var(dwarf_strict,0) Init(-1)
1552 Emit DWARF additions beyond selected version
1555 Common Report RejectNegative Var(dwarf_strict,1) VarExists
1556 Don't emit DWARF additions beyond selected version
1559 Common Report Var(flag_gtoggle)
1560 Toggle debug information generation
1563 Common JoinedOrMissing Negative(gxcoff)
1564 Generate debug information in VMS format
1567 Common JoinedOrMissing Negative(gxcoff+)
1568 Generate debug information in XCOFF format
1571 Common JoinedOrMissing Negative(gcoff)
1572 Generate debug information in extended XCOFF format
1575 Common Joined Var(plugindir_string) Init(0)
1576 -iplugindir=<dir> Set <dir> to be the default plugin directory
1579 Common Joined Separate
1580 -o <file> Place output into <file>
1583 Common Var(profile_flag)
1584 Enable function profiling
1587 Common Var(pedantic)
1588 Issue warnings needed for strict compliance to the standard
1592 Like -pedantic but issue them as errors
1595 Common Var(quiet_flag)
1596 Do not display functions compiled or elapsed time
1599 Common Var(version_flag)
1600 Display the compiler's version
1603 Common Var(inhibit_warnings)
1607 Common RejectNegative Negative(pie)
1608 Create a shared library
1611 Common RejectNegative Negative(shared)
1612 Create a position independent executable
1614 ; This comment is to ensure we retain the blank line above.