1 ; Options for the language- and target-independent parts of the compiler.
3 ; Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008
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 three 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).
52 --param <param>=<value> Set parameter <param> to value. See below for a complete list of parameters
58 Common Joined Separate UInteger
59 -G<number> Put global and static data smaller than <number> bytes into a special section (on some targets)
62 Common JoinedOrMissing Optimization
63 -O<number> Set optimization level to <number>
67 Optimize for space rather than speed
71 This switch is deprecated; use -Wextra instead
74 Common Var(warn_aggregate_return) Warning
75 Warn about returning structures, unions or arrays
78 Common Var(warn_array_bounds) Warning
79 Warn if an array is accessed out of bounds
82 Common Var(warn_attributes) Init(1) Warning
83 Warn about inappropriate attribute usage
86 Common Var(warn_cast_align) Warning
87 Warn about pointer casts which increase alignment
89 Wdeprecated-declarations
90 Common Var(warn_deprecated_decl) Init(1) Warning
91 Warn about uses of __attribute__((deprecated)) declarations
93 Wdisabled-optimization
94 Common Var(warn_disabled_optimization) Warning
95 Warn when an optimization pass is disabled
97 Wdisallowed-function-list=
98 Common RejectNegative Joined Warning
99 Warn on calls to these functions
102 Common Var(warnings_are_errors)
103 Treat all warnings as errors
107 Treat specified warning as error
111 Print extra (possibly unwanted) warnings
114 Common Var(flag_fatal_errors)
115 Exit on the first error occurred
118 Common RejectNegative Joined UInteger
119 -Wframe-larger-than=<number> Warn if a function's stack frame requires more than <number> bytes
122 Common Var(warn_inline) Warning
123 Warn when an inlined function cannot be inlined
126 Common RejectNegative Joined UInteger Warning
129 Common RejectNegative Joined UInteger Warning
130 -Wlarger-than=<number> Warn if an object is larger than <number> bytes
133 Common Warning Var(warn_logical_op)
134 Warn when a logical operator is suspicously always evaluating to true or false
136 Wunsafe-loop-optimizations
137 Common Var(warn_unsafe_loop_optimizations) Warning
138 Warn if the loop cannot be optimized due to nontrivial assumptions.
141 Common Var(warn_missing_noreturn) Warning
142 Warn about functions which might be candidates for __attribute__((noreturn))
145 Common Var(warn_mudflap) Init(1) Warning
146 Warn about constructs not instrumented by -fmudflap
149 Common Var(warn_overflow) Init(1) Warning
150 Warn about overflow in arithmetic expressions
153 Common Var(warn_packed) Warning
154 Warn when the packed attribute has no effect on struct layout
157 Common Var(warn_padded) Warning
158 Warn when padding is required to align structure members
161 Common Var(warn_shadow) Warning
162 Warn when one local variable shadows another
165 Common Var(warn_stack_protect) Warning
166 Warn when not issuing stack smashing protection for some reason
170 Warn about code which might break strict aliasing rules
173 Common Joined UInteger Var(warn_strict_aliasing) Init(-1) Warning
174 Warn about code which might break strict aliasing rules
178 Warn about optimizations that assume that signed overflow is undefined
181 Common Joined UInteger Var(warn_strict_overflow) Init(-1) Warning
182 Warn about optimizations that assume that signed overflow is undefined
185 Common Var(warn_switch) Warning
186 Warn about enumerated switches, with no default, missing a case
189 Common Var(warn_switch_default) Warning
190 Warn about enumerated switches missing a \"default:\" statement
193 Common Var(warn_switch_enum) Warning
194 Warn about all enumerated switches missing a specific case
197 Common Var(warn_system_headers) Warning
198 Do not suppress warnings from system headers
201 Common Var(warn_type_limits) Init(-1) Warning
202 Warn if a comparison is always true or always false due to the limited range of the data type
205 Common Var(warn_uninitialized) Warning
206 Warn about uninitialized automatic variables
209 Common Var(warn_notreached) Warning
210 Warn about code that will never be executed
213 Common Var(warn_unused) Init(0) Warning
214 Enable all -Wunused- warnings
217 Common Var(warn_unused_function) Init(-1) Warning
218 Warn when a function is unused
221 Common Var(warn_unused_label) Init(-1) Warning
222 Warn when a label is unused
225 Common Var(warn_unused_parameter) Init(-1) Warning
226 Warn when a function parameter is unused
229 Common Var(warn_unused_value) Init(-1) Warning
230 Warn when an expression value is unused
233 Common Var(warn_unused_variable) Init(-1) Warning
234 Warn when a variable is unused
237 Common RejectNegative Var(warn_coverage_mismatch) Warning
238 Warn instead of error in case profiles in -fprofile-use do not match
242 -aux-info <file> Emit declaration information into <file>
255 -d<letters> Enable dumps from specific passes of the compiler
259 -dumpbase <file> Set the file basename to be used for dumps
261 ; The version of the C++ ABI in use. The following values are allowed:
263 ; 0: The version of the ABI believed most conformant with the C++ ABI
264 ; specification. This ABI may change as bugs are discovered and fixed.
265 ; Therefore, 0 will not necessarily indicate the same ABI in different
268 ; 1: The version of the ABI first used in G++ 3.2.
270 ; 2: The version of the ABI first used in G++ 3.4.
272 ; Additional positive integers will be assigned as new versions of
273 ; the ABI become the default version of the ABI.
275 Common Joined UInteger Var(flag_abi_version) Init(2)
278 Common Report Var(align_functions,0) Optimization UInteger
279 Align the start of functions
282 Common RejectNegative Joined UInteger
285 Common Report Var(align_jumps,0) Optimization UInteger
286 Align labels which are only reached by jumping
289 Common RejectNegative Joined UInteger
292 Common Report Var(align_labels,0) Optimization UInteger
296 Common RejectNegative Joined UInteger
299 Common Report Var(align_loops) Optimization UInteger
300 Align the start of loops
303 Common RejectNegative Joined UInteger
305 ; This flag is only tested if alias checking is enabled.
306 ; 0 if pointer arguments may alias each other. True in C.
307 ; 1 if pointer arguments may not alias each other but may alias
309 ; 2 if pointer arguments may not alias each other and may not
310 ; alias global variables.
311 ; 3 if pointer arguments may not alias anything. True in Fortran.
312 ; Set by the front end.
314 Common Report Var(flag_argument_noalias,0) Optimization
315 Specify that arguments may alias each other and globals
318 Common Report Var(flag_argument_noalias,1) VarExists Optimization
319 Assume arguments may alias globals but not each other
321 fargument-noalias-global
322 Common Report Var(flag_argument_noalias,2) VarExists Optimization
323 Assume arguments alias neither each other nor globals
325 fargument-noalias-anything
326 Common Report Var(flag_argument_noalias,3) VarExists Optimization
327 Assume arguments alias no other storage
329 fasynchronous-unwind-tables
330 Common Report Var(flag_asynchronous_unwind_tables) Optimization
331 Generate unwind tables that are exact at each instruction boundary
334 Common Report Var(flag_auto_inc_dec) Init(1)
335 Generate auto-inc/dec instructions
337 ; -fcheck-bounds causes gcc to generate array bounds checks.
338 ; For C, C++ and ObjC: defaults off.
339 ; For Java: defaults to on.
340 ; For Fortran: defaults to off.
342 Common Report Var(flag_bounds_check)
343 Generate code to check bounds before indexing arrays
346 Common Report Var(flag_branch_on_count_reg) Init(1) Optimization
347 Replace add, compare, branch with branch on count register
349 fbranch-probabilities
350 Common Report Var(flag_branch_probabilities) Optimization
351 Use profiling information for branch probabilities
353 fbranch-target-load-optimize
354 Common Report Var(flag_branch_target_load_optimize) Optimization
355 Perform branch target load optimization before prologue / epilogue threading
357 fbranch-target-load-optimize2
358 Common Report Var(flag_branch_target_load_optimize2) Optimization
359 Perform branch target load optimization after prologue / epilogue threading
362 Common Report Var(flag_btr_bb_exclusive) Optimization
363 Restrict target load migration not to re-use registers in any basic block
366 Common Joined RejectNegative
367 -fcall-saved-<register> Mark <register> as being preserved across functions
370 Common Joined RejectNegative
371 -fcall-used-<register> Mark <register> as being corrupted by function calls
373 ; Nonzero for -fcaller-saves: allocate values in regs that need to
374 ; be saved across function calls, if that produces overall better code.
375 ; Optional now, so people can test it.
377 Common Report Var(flag_caller_saves) Optimization
378 Save registers around function calls
381 Common Report Var(flag_check_data_deps)
382 Compare the results of several data dependence analyzers.
385 Common Report Var(flag_no_common,0) Optimization
386 Do not put uninitialized globals in the common section
389 Common Var(flag_conserve_stack,0) Optimization
390 Do not perform optimizations increasing noticeably stack usage
393 Common Report Var(flag_cprop_registers) Optimization
394 Perform a register copy-propagation optimization pass
397 Common Report Var(flag_crossjumping) Optimization
398 Perform cross-jumping optimization
401 Common Report Var(flag_cse_follow_jumps) Optimization
402 When running CSE, follow jumps to their targets
405 Common Report Var(flag_cse_skip_blocks) Optimization
406 When running CSE, follow conditional jumps
409 Common Report Var(flag_cx_limited_range) Optimization
410 Omit range reduction step when performing complex division
413 Common Report Var(flag_cx_fortran_rules) Optimization
414 Complex multiplication and division follow Fortran rules
417 Common Report Var(flag_data_sections) Optimization
418 Place data items into their own section
422 List all available debugging counters with their limits and counts.
425 Common RejectNegative Joined
426 -fdbg-cnt=<counter>:<limit>[,<counter>:<limit>,...] Set the debug counter limit.
429 Common Joined RejectNegative
430 Map one directory name to another in debug information
432 ; Nonzero for -fdefer-pop: don't pop args after each function call
433 ; instead save them up to pop many calls' args with one insns.
435 Common Report Var(flag_defer_pop) Optimization
436 Defer popping functions args from stack until later
439 Common Report Var(flag_delayed_branch) Optimization
440 Attempt to fill delay slots of branch instructions
442 fdelete-null-pointer-checks
443 Common Report Var(flag_delete_null_pointer_checks) Optimization
444 Delete useless null pointer checks
446 fdiagnostics-show-location=
447 Common Joined RejectNegative
448 -fdiagnostics-show-location=[once|every-line] How often to emit source location at the beginning of line-wrapped diagnostics
450 fdiagnostics-show-option
452 Amend appropriate diagnostic messages with the command line option that controls them
455 Common Joined RejectNegative
456 -fdump-<type> Dump various compiler internals to a file
459 Common Report Var(flag_dump_noaddr)
460 Suppress output of addresses in debugging dumps
463 Common Report Var(flag_dump_unnumbered) VarExists
464 Suppress output of instruction numbers, line number notes and addresses in debugging dumps
467 Common Report Var(flag_dwarf2_cfi_asm) Init(HAVE_GAS_CFI_DIRECTIVE)
468 Enable CFI tables via GAS assembler directives.
471 Common Report Var(flag_early_inlining) Init(1) Optimization
472 Perform early inlining
474 feliminate-dwarf2-dups
475 Common Report Var(flag_eliminate_dwarf2_dups)
476 Perform DWARF2 duplicate elimination
478 feliminate-unused-debug-symbols
479 Common Report Var(flag_debug_only_used_symbols)
480 Perform unused type elimination in debug info
482 feliminate-unused-debug-types
483 Common Report Var(flag_eliminate_unused_debug_types) Init(1)
484 Perform unused type elimination in debug info
486 femit-class-debug-always
487 Common Report Var(flag_emit_class_debug_always) Init(0)
488 Do not suppress C++ class debug information.
491 Common Report Var(flag_exceptions) Optimization
492 Enable exception handling
494 fexpensive-optimizations
495 Common Report Var(flag_expensive_optimizations) Optimization
496 Perform a number of minor, expensive optimizations
502 Common Report Var(flag_finite_math_only) Optimization
503 Assume no NaNs or infinities are generated
506 Common Joined RejectNegative
507 -ffixed-<register> Mark <register> as being unavailable to the compiler
510 Common Report Var(flag_float_store) Optimization
511 Don't allocate floats and doubles in extended-precision registers
515 Does nothing. Preserved for backward compatibility.
518 Common Report Var(flag_forward_propagate) Optimization
519 Perform a forward propagation pass on RTL
521 ; Nonzero means don't put addresses of constant functions in registers.
522 ; Used for compiling the Unix kernel, where strange substitutions are
523 ; done on the assembly output.
525 Common Report Var(flag_no_function_cse,0)
526 Allow function addresses to be held in registers
529 Common Report Var(flag_function_sections)
530 Place each function into its own section
533 Common Report Var(flag_gcse) Optimization
534 Perform global common subexpression elimination
537 Common Report Var(flag_gcse_lm) Init(1) Optimization
538 Perform enhanced load motion during global common subexpression elimination
541 Common Report Var(flag_gcse_sm) Init(0) Optimization
542 Perform store motion after global common subexpression elimination
545 Common Report Var(flag_gcse_las) Init(0) Optimization
546 Perform redundant load after store elimination in global common subexpression
550 Common Report Var(flag_gcse_after_reload) Optimization
551 Perform global common subexpression elimination after register allocation
554 ; This option is not documented yet as its semantics will change.
556 Common Report Var(flag_graphite)
557 Enable in and out of Graphite representation
560 Common Report Var(flag_loop_strip_mine) Optimization
561 Enable Loop Strip Mining transformation
564 Common Report Var(flag_loop_interchange) Optimization
565 Enable Loop Interchange transformation
568 Common Report Var(flag_loop_block) Optimization
569 Enable Loop Blocking transformation
571 ; This option is not documented as it does not perform any useful optimization.
573 Common Report Var(flag_graphite_identity) Optimization
574 Enable Graphite Identity transformation
576 fguess-branch-probability
577 Common Report Var(flag_guess_branch_prob) Optimization
578 Enable guessing of branch probabilities
580 ; Nonzero means ignore `#ident' directives. 0 means handle them.
581 ; Generate position-independent code for executables if possible
582 ; On SVR4 targets, it also controls whether or not to emit a
583 ; string identifying the compiler.
585 Common Report Var(flag_no_ident,0)
586 Process #ident directives
589 Common Report Var(flag_if_conversion) Optimization
590 Perform conversion of conditional jumps to branchless equivalents
593 Common Report Var(flag_if_conversion2) Optimization
594 Perform conversion of conditional jumps to conditional execution
596 ; -finhibit-size-directive inhibits output of .size for ELF.
597 ; This is used only for compiling crtstuff.c,
598 ; and it may be extended to other effects
599 ; needed for crtstuff.c on other systems.
600 finhibit-size-directive
601 Common Report Var(flag_inhibit_size_directive)
602 Do not generate .size directives
605 Common Report Var(flag_indirect_inlining)
606 Perform indirect inlining
608 ; Nonzero means that functions declared `inline' will be treated
609 ; as `static'. Prevents generation of zillions of copies of unused
610 ; static inline functions; instead, `inlines' are written out
611 ; only when actually used. Used in conjunction with -g. Also
612 ; does the right thing with #pragma interface.
614 Common Report Var(flag_no_inline,0) Init(0)
615 Pay attention to the \"inline\" keyword
617 finline-small-functions
618 Common Report Var(flag_inline_small_functions) Optimization
619 Integrate simple functions into their callers when code size is known to not growth
622 Common Report Var(flag_inline_functions) Optimization
623 Integrate simple functions into their callers
625 finline-functions-called-once
626 Common Report Var(flag_inline_functions_called_once) Init(1) Optimization
627 Integrate functions called once into their callers
630 Common RejectNegative Joined UInteger
633 Common RejectNegative Joined UInteger
634 -finline-limit=<number> Limit the size of inlined functions to <number>
636 finstrument-functions
637 Common Report Var(flag_instrument_function_entry_exit)
638 Instrument function entry and exit with profiling calls
640 finstrument-functions-exclude-function-list=
641 Common RejectNegative Joined
642 -finstrument-functions-exclude-function-list=name,... Do not instrument listed functions
644 finstrument-functions-exclude-file-list=
645 Common RejectNegative Joined
646 -finstrument-functions-exclude-file-list=filename,... Do not instrument functions listed in files
649 Common Report Var(flag_ipa_cp) Optimization
650 Perform Interprocedural constant propagation
653 Common Report Var(flag_ipa_cp_clone) Optimization
654 Perform cloning to make Interprocedural constant propagation stronger
657 Common Report Var(flag_ipa_pure_const) Init(0) Optimization
658 Discover pure and const functions
661 Common Report Var(flag_ipa_pta) Init(0) Optimization
662 Perform interprocedural points-to analysis
665 Common Report Var(flag_ipa_reference) Init(0) Optimization
666 Discover readonly and non addressable static variables
669 Common Report Var(flag_ipa_type_escape) Init(0) Optimization
670 Type based escape and alias analysis
673 Common Report Var(flag_ipa_matrix_reorg) Optimization
674 Perform matrix layout flattening and transposing based
675 on profiling information.
678 Common Report Var(flag_ipa_struct_reorg)
679 Perform structure layout optimizations based
680 on profiling information.
683 Common Joined RejectNegative
684 -fira-algorithm=[CB|priority] Set the used IRA algorithm
687 Common Joined RejectNegative
688 -fira-region=[one|all|mixed] Set regions for IRA
691 Common Report Var(flag_ira_coalesce) Init(0)
692 Do optimistic coalescing.
694 fira-share-save-slots
695 Common Report Var(flag_ira_share_save_slots) Init(1)
696 Share slots for saving different hard registers.
698 fira-share-spill-slots
699 Common Report Var(flag_ira_share_spill_slots) Init(1)
700 Share stack slots for spilled pseudo-registers.
703 Common RejectNegative Joined UInteger
704 -fira-verbose=<number> Control IRA's level of diagnostic messages.
707 Common Report Var(flag_ivopts) Init(1) Optimization
708 Optimize induction variables on trees
711 Common Var(flag_jump_tables) Init(1) Optimization
712 Use jump tables for sufficiently large switch statements
714 fkeep-inline-functions
715 Common Report Var(flag_keep_inline_functions)
716 Generate code for functions even if they are fully inlined
719 Common Report Var(flag_keep_static_consts) Init(1)
720 Emit static const variables even if they are not used
723 Common Report Var(flag_leading_underscore) Init(-1)
724 Give external symbols a leading underscore
728 Does nothing. Preserved for backward compatibility.
731 Common Report Var(flag_errno_math) Init(1) Optimization
732 Set errno after built-in math functions
735 Common Report Var(mem_report)
736 Report on permanent memory allocation
738 ; This will attempt to merge constant section constants, if 1 only
739 ; string constants and constants from constant pool, if 2 also constant
742 Common Report Var(flag_merge_constants,2) Init(1) Optimization
743 Attempt to merge identical constants and constant variables
746 Common Report Var(flag_merge_constants,1) VarExists Optimization
747 Attempt to merge identical constants across compilation units
750 Common Report Var(flag_merge_debug_strings) Init(1)
751 Attempt to merge identical debug strings across compilation units
754 Common RejectNegative Joined UInteger
755 -fmessage-length=<number> Limit diagnostics to <number> characters per line. 0 suppresses line-wrapping
758 Common Report Var(flag_modulo_sched) Optimization
759 Perform SMS based modulo scheduling before the first scheduling pass
761 fmodulo-sched-allow-regmoves
762 Common Report Var(flag_modulo_sched_allow_regmoves)
763 Perform SMS based modulo scheduling with register moves allowed
765 fmove-loop-invariants
766 Common Report Var(flag_move_loop_invariants) Init(1) Optimization
767 Move loop invariant computations out of loops
770 Common RejectNegative Report Var(flag_mudflap)
771 Add mudflap bounds-checking instrumentation for single-threaded program
774 Common RejectNegative Report VarExists Var(flag_mudflap,2)
775 Add mudflap bounds-checking instrumentation for multi-threaded program
778 Common RejectNegative Report Var(flag_mudflap_ignore_reads)
779 Ignore read operations when inserting mudflap instrumentation
782 Common Var(flag_dce) Init(1) Optimization
783 Use the RTL dead code elimination pass
786 Common Var(flag_dse) Init(1) Optimization
787 Use the RTL dead store elimination pass
789 freschedule-modulo-scheduled-loops
790 Common Report Var(flag_resched_modulo_sched) Optimization
791 Enable/Disable the traditional scheduling in loops that already passed modulo scheduling
794 Common Report Var(flag_non_call_exceptions) Optimization
795 Support synchronous non-call exceptions
798 Common Report Var(flag_omit_frame_pointer) Optimization
799 When possible do not generate stack frames
801 foptimize-register-move
802 Common Report Var(flag_regmove) Optimization
803 Do the full register move optimization pass
805 foptimize-sibling-calls
806 Common Report Var(flag_optimize_sibling_calls) Optimization
807 Optimize sibling and tail recursive calls
810 Common Report Var(pre_ipa_mem_report)
811 Report on memory allocation before interprocedural optimization
814 Common Report Var(post_ipa_mem_report)
815 Report on memory allocation before interprocedural optimization
818 Common Report Var(flag_pack_struct) Optimization
819 Pack structure members together without holes
822 Common RejectNegative Joined UInteger Optimization
823 -fpack-struct=<number> Set initial maximum structure member alignment
826 Common Report Var(flag_pcc_struct_return,1) VarExists
827 Return small aggregates in memory, not registers
830 Common Report Var(flag_peel_loops) Optimization
834 Common Report Var(flag_no_peephole,0) Optimization
835 Enable machine specific peephole optimizations
838 Common Report Var(flag_peephole2) Optimization
839 Enable an RTL peephole pass before sched2
842 Common Report Var(flag_pic,2)
843 Generate position-independent code if possible (large mode)
846 Common Report Var(flag_pie,2)
847 Generate position-independent code for executables if possible (large mode)
850 Common Report Var(flag_pic,1) VarExists
851 Generate position-independent code if possible (small mode)
854 Common Report Var(flag_pie,1) VarExists
855 Generate position-independent code for executables if possible (small mode)
857 fpredictive-commoning
858 Common Report Var(flag_predictive_commoning) Optimization
859 Run predictive commoning optimization.
861 fprefetch-loop-arrays
862 Common Report Var(flag_prefetch_loop_arrays) Optimization
863 Generate prefetch instructions, if available, for arrays in loops
866 Common Report Var(profile_flag)
867 Enable basic program profiling code
870 Common Report Var(profile_arc_flag)
871 Insert arc-based program profiling code
874 Common Joined RejectNegative
875 Set the top-level directory for storing the profile data.
876 The default is 'pwd'.
879 Common Report Var(flag_profile_correction)
880 Enable correction of flow inconsistent profile data input
884 Enable common options for generating profile info for profile feedback directed optimizations
887 Common Joined RejectNegative
888 Enable common options for generating profile info for profile feedback directed optimizations, and set -fprofile-dir=
891 Common Var(flag_profile_use)
892 Enable common options for performing profile feedback directed optimizations
895 Common Joined RejectNegative
896 Enable common options for performing profile feedback directed optimizations, and set -fprofile-dir=
899 Common Report Var(flag_profile_values)
900 Insert code to profile values of expressions
906 Common Joined RejectNegative
907 -frandom-seed=<string> Make compile reproducible using <string>
909 ; This switch causes the command line that was used to create an
910 ; object file to be recorded into the object file. The exact format
911 ; of this recording is target and binary file format dependent.
912 ; It is related to the -fverbose-asm switch, but that switch only
913 ; records information in the assembler output file as comments, so
914 ; they never reach the object file.
916 Common Report Var(flag_record_gcc_switches)
917 Record gcc command line switches in the object file.
920 Common Report Var(flag_pcc_struct_return,0) VarExists Optimization
921 Return small aggregates in registers
924 Common Report Var(flag_regmove) Optimization
925 Enables a register move optimization
928 Common Report Var(flag_rename_registers) Init(2) Optimization
929 Perform a register renaming optimization pass
932 Common Report Var(flag_reorder_blocks) Optimization
933 Reorder basic blocks to improve code placement
935 freorder-blocks-and-partition
936 Common Report Var(flag_reorder_blocks_and_partition) Optimization
937 Reorder basic blocks and partition into hot and cold sections
940 Common Report Var(flag_reorder_functions) Optimization
941 Reorder functions to improve code placement
943 frerun-cse-after-loop
944 Common Report Var(flag_rerun_cse_after_loop) Init(2) Optimization
945 Add a common subexpression elimination pass after loop optimizations
949 Does nothing. Preserved for backward compatibility.
952 Common Report Var(flag_rounding_math) Optimization
953 Disable optimizations that assume default FP rounding behavior
956 Common Report Var(flag_schedule_interblock) Init(1) Optimization
957 Enable scheduling across basic blocks
960 Common Report Var(flag_schedule_speculative) Init(1) Optimization
961 Allow speculative motion of non-loads
964 Common Report Var(flag_schedule_speculative_load) Optimization
965 Allow speculative motion of some loads
967 fsched-spec-load-dangerous
968 Common Report Var(flag_schedule_speculative_load_dangerous) Optimization
969 Allow speculative motion of more loads
972 Common RejectNegative Joined
973 -fsched-verbose=<number> Set the verbosity level of the scheduler
975 fsched2-use-superblocks
976 Common Report Var(flag_sched2_use_superblocks) Optimization
977 If scheduling post reload, do superblock scheduling
980 Common Report Var(flag_sched2_use_traces) Optimization
981 If scheduling post reload, do trace scheduling
984 Common Report Var(flag_schedule_insns) Optimization
985 Reschedule instructions before register allocation
988 Common Report Var(flag_schedule_insns_after_reload) Optimization
989 Reschedule instructions after register allocation
991 ; This flag should be on when a target implements non-trivial
992 ; scheduling hooks, maybe saving some information for its own sake.
993 ; On IA64, for example, this is used for correct bundling.
994 fselective-scheduling
995 Common Report Var(flag_selective_scheduling) Optimization
996 Schedule instructions using selective scheduling algorithm
998 fselective-scheduling2
999 Common Report Var(flag_selective_scheduling2) Optimization
1000 Run selective scheduling after reload
1002 fsel-sched-pipelining
1003 Common Report Var(flag_sel_sched_pipelining) Init(0) Optimization
1004 Perform software pipelining of inner loops during selective scheduling
1006 fsel-sched-pipelining-outer-loops
1007 Common Report Var(flag_sel_sched_pipelining_outer_loops) Init(0) Optimization
1008 Perform software pipelining of outer loops during selective scheduling
1010 fsel-sched-reschedule-pipelined
1011 Common Report Var(flag_sel_sched_reschedule_pipelined) Init(0) Optimization
1012 Reschedule pipelined regions without pipelining
1014 ; sched_stalled_insns means that insns can be moved prematurely from the queue
1015 ; of stalled insns into the ready list.
1016 fsched-stalled-insns
1017 Common Report Var(flag_sched_stalled_insns) Optimization UInteger
1018 Allow premature scheduling of queued insns
1020 fsched-stalled-insns=
1021 Common RejectNegative Joined UInteger
1022 -fsched-stalled-insns=<number> Set number of queued insns that can be prematurely scheduled
1024 ; sched_stalled_insns_dep controls how many recently scheduled cycles will
1025 ; be examined for a dependency on a stalled insn that is candidate for
1026 ; premature removal from the queue of stalled insns into the ready list (has
1027 ; an effect only if the flag 'sched_stalled_insns' is set).
1028 fsched-stalled-insns-dep
1029 Common Report Var(flag_sched_stalled_insns_dep,1) Init(1) Optimization UInteger
1030 Set dependence distance checking in premature scheduling of queued insns
1032 fsched-stalled-insns-dep=
1033 Common RejectNegative Joined UInteger
1034 -fsched-stalled-insns-dep=<number> Set dependence distance checking in premature scheduling of queued insns
1037 Common Report Var(flag_section_anchors) Optimization
1038 Access data in the same section from shared anchor points
1040 frtl-abstract-sequences
1041 Common Report Var(flag_rtl_seqabstr) Optimization
1042 Perform sequence abstraction optimization on RTL
1045 Common Report Var(flag_see) Init(0)
1046 Eliminate redundant sign extensions using LCM.
1049 Common C ObjC C++ ObjC++ Report Var(flag_show_column) Init(0)
1050 Show column numbers in diagnostics, when available. Default off
1053 Common Report Var(flag_signaling_nans) Optimization
1054 Disable optimizations observable by IEEE signaling NaNs
1057 Common Report Var(flag_signed_zeros) Init(1) Optimization
1058 Disable floating point optimizations that ignore the IEEE signedness of zero
1060 fsingle-precision-constant
1061 Common Report Var(flag_single_precision_constant) Optimization
1062 Convert floating point constants to single precision constants
1064 fsplit-ivs-in-unroller
1065 Common Report Var(flag_split_ivs_in_unroller) Init(1) Optimization
1066 Split lifetimes of induction variables when loops are unrolled
1069 Common Report Var(flag_split_wide_types) Optimization
1070 Split wide types into independent registers
1072 fvariable-expansion-in-unroller
1073 Common Report Var(flag_variable_expansion_in_unroller) Optimization
1074 Apply variable expansion when loops are unrolled
1077 Common Report RejectNegative Joined
1078 -fstack-check=[no|generic|specific] Insert stack checking code into the program
1082 Insert stack checking code into the program. Same as -fstack-check=specific
1087 fstack-limit-register=
1088 Common RejectNegative Joined
1089 -fstack-limit-register=<register> Trap if the stack goes past <register>
1091 fstack-limit-symbol=
1092 Common RejectNegative Joined
1093 -fstack-limit-symbol=<name> Trap if the stack goes past symbol <name>
1096 Common Report Var(flag_stack_protect, 1)
1097 Use propolice as a stack protection method
1099 fstack-protector-all
1100 Common Report RejectNegative Var(flag_stack_protect, 2) VarExists
1101 Use a stack protection method for every function
1105 Does nothing. Preserved for backward compatibility.
1107 ; Nonzero if we should do (language-dependent) alias analysis.
1108 ; Typically, this analysis will assume that expressions of certain
1109 ; types do not alias expressions of certain other types. Only used
1110 ; if alias analysis (in general) is enabled.
1112 Common Report Var(flag_strict_aliasing) Optimization
1113 Assume strict aliasing rules apply
1116 Common Report Var(flag_strict_overflow)
1117 Treat signed overflow as undefined
1120 Common Report Var(flag_syntax_only)
1121 Check for syntax errors, then stop
1124 Common Report Var(flag_test_coverage)
1125 Create data files needed by \"gcov\"
1128 Common Report Var(flag_thread_jumps) Optimization
1129 Perform jump threading optimizations
1132 Common Report Var(time_report)
1133 Report the time taken by each compiler pass
1136 Common Joined RejectNegative
1137 -ftls-model=[global-dynamic|local-dynamic|initial-exec|local-exec] Set the default thread-local storage code generation model
1140 Common Report Var(flag_toplevel_reorder) Init(2) Optimization
1141 Reorder top level functions, variables, and asms
1144 Common Report Var(flag_tracer)
1145 Perform superblock formation via tail duplication
1147 ; Zero means that floating-point math operations cannot generate a
1148 ; (user-visible) trap. This is the case, for example, in nonstop
1149 ; IEEE 754 arithmetic.
1151 Common Report Var(flag_trapping_math) Init(1) Optimization
1152 Assume floating-point operations can trap
1155 Common Report Var(flag_trapv) Optimization
1156 Trap for signed overflow in addition, subtraction and multiplication
1159 Common Report Var(flag_tree_ccp) Optimization
1160 Enable SSA-CCP optimization on trees
1164 Does nothing. Preserved for backward compatibility.
1167 Common Report Var(flag_tree_ch) Optimization
1168 Enable loop header copying on trees
1171 Common Report Var(flag_tree_copyrename) Optimization
1172 Replace SSA temporaries with better names in copies
1175 Common Report Var(flag_tree_copy_prop) Optimization
1176 Enable copy propagation on trees
1178 ftree-store-copy-prop
1180 Does nothing. Preserved for backward compatibility.
1183 Common Report Var(flag_tree_cselim) Init(2) Optimization
1184 Transform condition stores into unconditional ones
1186 ftree-switch-conversion
1187 Common Report Var(flag_tree_switch_conversion) Optimization
1188 Perform conversions of switch initializations.
1191 Common Report Var(flag_tree_dce) Optimization
1192 Enable SSA dead code elimination optimization on trees
1194 ftree-dominator-opts
1195 Common Report Var(flag_tree_dom) Optimization
1196 Enable dominator optimizations
1199 Common Report Var(flag_tree_dse) Optimization
1200 Enable dead store elimination
1203 Common Report Var(flag_tree_fre) Optimization
1204 Enable Full Redundancy Elimination (FRE) on trees
1206 ftree-loop-distribution
1207 Common Report Var(flag_tree_loop_distribution) Optimization
1208 Enable loop distribution on trees
1211 Common Report Var(flag_tree_loop_im) Init(1) Optimization
1212 Enable loop invariant motion on trees
1215 Common Report Var(flag_tree_loop_linear) Optimization
1216 Enable linear loop transforms on trees
1219 Common Report Var(flag_tree_loop_ivcanon) Init(1) Optimization
1220 Create canonical induction variables in loops
1223 Common Report Var(flag_tree_loop_optimize) Init(1) Optimization
1224 Enable loop optimizations on tree level
1226 ftree-parallelize-loops=
1227 Common Report Joined UInteger Var(flag_tree_parallelize_loops) Init(1)
1228 Enable automatic parallelization of loops
1231 Common Report Var(flag_tree_pre) Optimization
1232 Enable SSA-PRE optimization on trees
1235 Common Report Var(flag_tree_reassoc) Init(1) Optimization
1236 Enable reassociation on tree level
1240 Does nothing. Preserved for backward compatibility.
1243 Common Report Var(flag_tree_sink) Optimization
1244 Enable SSA code sinking on trees
1247 Common Report Var(flag_tree_sra) Optimization
1248 Perform scalar replacement of aggregates
1251 Common Report Var(flag_tree_ter) Init(1) Optimization
1252 Replace temporary expressions in the SSA->normal pass
1255 Common Report Var(flag_tree_live_range_split) Optimization
1256 Perform live range splitting during the SSA->normal pass
1259 Common Report Var(flag_tree_vrp) Init(0) Optimization
1260 Perform Value Range Propagation on trees
1263 Common Report Var(flag_unit_at_a_time) Init(1) Optimization
1264 Compile whole compilation unit at a time
1267 Common Report Var(flag_unroll_loops) Optimization
1268 Perform loop unrolling when iteration count is known
1271 Common Report Var(flag_unroll_all_loops) Optimization
1272 Perform loop unrolling for all loops
1274 ; Nonzero means that loop optimizer may assume that the induction variables
1275 ; that control loops do not overflow and that the loops with nontrivial
1276 ; exit condition are not infinite
1277 funsafe-loop-optimizations
1278 Common Report Var(flag_unsafe_loop_optimizations) Optimization
1279 Allow loop optimizations to assume that the loops behave in normal way
1282 Common Report Var(flag_associative_math)
1283 Allow optimization for floating-point arithmetic which may change the
1284 result of the operation due to rounding.
1287 Common Report Var(flag_reciprocal_math)
1288 Same as -fassociative-math for expressions which include division.
1290 ; Nonzero means that unsafe floating-point math optimizations are allowed
1291 ; for the sake of speed. IEEE compliance is not guaranteed, and operations
1292 ; are allowed to assume that their arguments and results are "normal"
1293 ; (e.g., nonnegative for SQRT).
1294 funsafe-math-optimizations
1295 Common Report Var(flag_unsafe_math_optimizations) Optimization
1296 Allow math optimizations that may violate IEEE or ISO standards
1299 Common Report Var(flag_unswitch_loops) Optimization
1300 Perform loop unswitching
1303 Common Report Var(flag_unwind_tables) Optimization
1304 Just generate unwind tables for exception handling
1307 Common Report Var(flag_var_tracking) VarExists Optimization
1308 Perform variable tracking
1310 fvar-tracking-uninit
1311 Common Report Var(flag_var_tracking_uninit) Optimization
1312 Perform variable tracking and also tag variables that are uninitialized
1315 Common Report Var(flag_tree_vectorize) Optimization
1316 Enable loop vectorization on trees
1319 Common Report Var(flag_vect_cost_model) Optimization
1320 Enable use of cost model in vectorization
1322 ftree-vect-loop-version
1323 Common Report Var(flag_tree_vect_loop_version) Init(1) Optimization
1324 Enable loop versioning when doing loop vectorization on trees
1326 ftree-vectorizer-verbose=
1327 Common RejectNegative Joined
1328 -ftree-vectorizer-verbose=<number> Set the verbosity level of the vectorizer
1331 Common Report Var(flag_tree_scev_cprop) Init(1) Optimization
1332 Enable copy propagation of scalar-evolution information.
1334 ; -fverbose-asm causes extra commentary information to be produced in
1335 ; the generated assembly code (to make it more readable). This option
1336 ; is generally only of use to those who actually need to read the
1337 ; generated assembly code (perhaps while debugging the compiler itself).
1338 ; -fno-verbose-asm, the default, causes the extra information
1339 ; to not be added and is useful when comparing two assembler files.
1341 Common Report Var(flag_verbose_asm)
1342 Add extra commentary to assembler output
1345 Common Joined RejectNegative
1346 -fvisibility=[default|internal|hidden|protected] Set the default symbol visibility
1350 Common Report Var(flag_value_profile_transformations) Optimization
1351 Use expression value profiles in optimizations
1354 Common Report Var(flag_web) Init(2) Optimization
1355 Construct webs and split unrelated uses of single variable
1357 ftree-builtin-call-dce
1358 Common Report Var(flag_tree_builtin_call_dce) Init(0) Optimization
1359 Enable conditional dead code elimination for builtin calls
1362 Common Report Var(flag_whole_program) Init(0) Optimization
1363 Perform whole program optimizations
1366 Common Report Var(flag_wrapv) Optimization
1367 Assume signed arithmetic overflow wraps around
1369 fzero-initialized-in-bss
1370 Common Report Var(flag_zero_initialized_in_bss) Init(1)
1371 Put zero initialized data in the bss section
1374 Common JoinedOrMissing
1375 Generate debug information in default format
1378 Common JoinedOrMissing Negative(gdwarf-2)
1379 Generate debug information in COFF format
1382 Common JoinedOrMissing Negative(gstabs)
1383 Generate debug information in DWARF v2 format
1386 Common JoinedOrMissing
1387 Generate debug information in default extended format
1390 Common JoinedOrMissing Negative(gstabs+)
1391 Generate debug information in STABS format
1394 Common JoinedOrMissing Negative(gvms)
1395 Generate debug information in extended STABS format
1398 Common JoinedOrMissing Negative(gxcoff)
1399 Generate debug information in VMS format
1402 Common JoinedOrMissing Negative(gxcoff+)
1403 Generate debug information in XCOFF format
1406 Common JoinedOrMissing Negative(gcoff)
1407 Generate debug information in extended XCOFF format
1410 Common Joined Separate
1411 -o <file> Place output into <file>
1414 Common Var(profile_flag)
1415 Enable function profiling
1418 Common Var(pedantic)
1419 Issue warnings needed for strict compliance to the standard
1423 Like -pedantic but issue them as errors
1426 Common Var(quiet_flag)
1427 Do not display functions compiled or elapsed time
1430 Common Var(version_flag)
1431 Display the compiler's version
1434 Common Var(inhibit_warnings)
1438 Common RejectNegative Negative(pie)
1439 Create a shared library
1442 Common RejectNegative Negative(shared)
1443 Create a position independent executable
1445 ; This comment is to ensure we retain the blank line above.