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
555 Common Report Var(flag_graphite)
556 Enable in and out of Graphite representation
559 Common Report Var(flag_loop_strip_mine) Optimization
560 Enable Loop Strip Mining transformation
563 Common Report Var(flag_loop_interchange) Optimization
564 Enable Loop Interchange transformation
567 Common Report Var(flag_loop_block) Optimization
568 Enable Loop Blocking transformation
571 Common Report Var(flag_graphite_identity) Optimization
572 Enable Graphite Identity transformation
574 fguess-branch-probability
575 Common Report Var(flag_guess_branch_prob) Optimization
576 Enable guessing of branch probabilities
578 ; Nonzero means ignore `#ident' directives. 0 means handle them.
579 ; Generate position-independent code for executables if possible
580 ; On SVR4 targets, it also controls whether or not to emit a
581 ; string identifying the compiler.
583 Common Report Var(flag_no_ident,0)
584 Process #ident directives
587 Common Report Var(flag_if_conversion) Optimization
588 Perform conversion of conditional jumps to branchless equivalents
591 Common Report Var(flag_if_conversion2) Optimization
592 Perform conversion of conditional jumps to conditional execution
594 ; -finhibit-size-directive inhibits output of .size for ELF.
595 ; This is used only for compiling crtstuff.c,
596 ; and it may be extended to other effects
597 ; needed for crtstuff.c on other systems.
598 finhibit-size-directive
599 Common Report Var(flag_inhibit_size_directive)
600 Do not generate .size directives
603 Common Report Var(flag_indirect_inlining)
604 Perform indirect inlining
606 ; Nonzero means that functions declared `inline' will be treated
607 ; as `static'. Prevents generation of zillions of copies of unused
608 ; static inline functions; instead, `inlines' are written out
609 ; only when actually used. Used in conjunction with -g. Also
610 ; does the right thing with #pragma interface.
612 Common Report Var(flag_no_inline,0) Init(0)
613 Pay attention to the \"inline\" keyword
615 finline-small-functions
616 Common Report Var(flag_inline_small_functions) Optimization
617 Integrate simple functions into their callers when code size is known to not growth
620 Common Report Var(flag_inline_functions) Optimization
621 Integrate simple functions into their callers
623 finline-functions-called-once
624 Common Report Var(flag_inline_functions_called_once) Init(1) Optimization
625 Integrate functions called once into their callers
628 Common RejectNegative Joined UInteger
631 Common RejectNegative Joined UInteger
632 -finline-limit=<number> Limit the size of inlined functions to <number>
634 finstrument-functions
635 Common Report Var(flag_instrument_function_entry_exit)
636 Instrument function entry and exit with profiling calls
638 finstrument-functions-exclude-function-list=
639 Common RejectNegative Joined
640 -finstrument-functions-exclude-function-list=name,... Do not instrument listed functions
642 finstrument-functions-exclude-file-list=
643 Common RejectNegative Joined
644 -finstrument-functions-exclude-file-list=filename,... Do not instrument functions listed in files
647 Common Report Var(flag_ipa_cp) Optimization
648 Perform Interprocedural constant propagation
651 Common Report Var(flag_ipa_cp_clone) Optimization
652 Perform cloning to make Interprocedural constant propagation stronger
655 Common Report Var(flag_ipa_pure_const) Init(0) Optimization
656 Discover pure and const functions
659 Common Report Var(flag_ipa_pta) Init(0) Optimization
660 Perform interprocedural points-to analysis
663 Common Report Var(flag_ipa_reference) Init(0) Optimization
664 Discover readonly and non addressable static variables
667 Common Report Var(flag_ipa_type_escape) Init(0) Optimization
668 Type based escape and alias analysis
671 Common Report Var(flag_ipa_matrix_reorg) Optimization
672 Perform matrix layout flattening and transposing based
673 on profiling information.
676 Common Report Var(flag_ipa_struct_reorg)
677 Perform structure layout optimizations based
678 on profiling information.
681 Common Report Var(flag_ira) Init(0)
682 Use integrated register allocator.
685 Common Joined RejectNegative
686 -fira-algorithm=[regional|CB|mixed] Set the used IRA algorithm
689 Common Report Var(flag_ira_coalesce) Init(0)
690 Do optimistic coalescing.
692 fira-share-save-slots
693 Common Report Var(flag_ira_share_save_slots) Init(1)
694 Share slots for saving different hard registers.
696 fira-share-spill-slots
697 Common Report Var(flag_ira_share_spill_slots) Init(1)
698 Share stack slots for spilled pseudo-registers.
701 Common RejectNegative Joined UInteger
702 -fira-verbose=<number> Control IRA's level of diagnostic messages.
705 Common Report Var(flag_ivopts) Init(1) Optimization
706 Optimize induction variables on trees
709 Common Var(flag_jump_tables) Init(1) Optimization
710 Use jump tables for sufficiently large switch statements
712 fkeep-inline-functions
713 Common Report Var(flag_keep_inline_functions)
714 Generate code for functions even if they are fully inlined
717 Common Report Var(flag_keep_static_consts) Init(1)
718 Emit static const variables even if they are not used
721 Common Report Var(flag_leading_underscore) Init(-1)
722 Give external symbols a leading underscore
726 Does nothing. Preserved for backward compatibility.
729 Common Report Var(flag_errno_math) Init(1) Optimization
730 Set errno after built-in math functions
733 Common Report Var(mem_report)
734 Report on permanent memory allocation
736 ; This will attempt to merge constant section constants, if 1 only
737 ; string constants and constants from constant pool, if 2 also constant
740 Common Report Var(flag_merge_constants,2) Init(1) Optimization
741 Attempt to merge identical constants and constant variables
744 Common Report Var(flag_merge_constants,1) VarExists Optimization
745 Attempt to merge identical constants across compilation units
748 Common Report Var(flag_merge_debug_strings) Init(1)
749 Attempt to merge identical debug strings across compilation units
752 Common RejectNegative Joined UInteger
753 -fmessage-length=<number> Limit diagnostics to <number> characters per line. 0 suppresses line-wrapping
756 Common Report Var(flag_modulo_sched) Optimization
757 Perform SMS based modulo scheduling before the first scheduling pass
759 fmodulo-sched-allow-regmoves
760 Common Report Var(flag_modulo_sched_allow_regmoves)
761 Perform SMS based modulo scheduling with register moves allowed
763 fmove-loop-invariants
764 Common Report Var(flag_move_loop_invariants) Init(1) Optimization
765 Move loop invariant computations out of loops
768 Common RejectNegative Report Var(flag_mudflap)
769 Add mudflap bounds-checking instrumentation for single-threaded program
772 Common RejectNegative Report VarExists Var(flag_mudflap,2)
773 Add mudflap bounds-checking instrumentation for multi-threaded program
776 Common RejectNegative Report Var(flag_mudflap_ignore_reads)
777 Ignore read operations when inserting mudflap instrumentation
780 Common Var(flag_dce) Init(1) Optimization
781 Use the RTL dead code elimination pass
784 Common Var(flag_dse) Init(1) Optimization
785 Use the RTL dead store elimination pass
787 freschedule-modulo-scheduled-loops
788 Common Report Var(flag_resched_modulo_sched) Optimization
789 Enable/Disable the traditional scheduling in loops that already passed modulo scheduling
792 Common Report Var(flag_non_call_exceptions) Optimization
793 Support synchronous non-call exceptions
796 Common Report Var(flag_omit_frame_pointer) Optimization
797 When possible do not generate stack frames
799 foptimize-register-move
800 Common Report Var(flag_regmove) Optimization
801 Do the full register move optimization pass
803 foptimize-sibling-calls
804 Common Report Var(flag_optimize_sibling_calls) Optimization
805 Optimize sibling and tail recursive calls
808 Common Report Var(pre_ipa_mem_report)
809 Report on memory allocation before interprocedural optimization
812 Common Report Var(post_ipa_mem_report)
813 Report on memory allocation before interprocedural optimization
816 Common Report Var(flag_pack_struct) Optimization
817 Pack structure members together without holes
820 Common RejectNegative Joined UInteger Optimization
821 -fpack-struct=<number> Set initial maximum structure member alignment
824 Common Report Var(flag_pcc_struct_return,1) VarExists
825 Return small aggregates in memory, not registers
828 Common Report Var(flag_peel_loops) Optimization
832 Common Report Var(flag_no_peephole,0) Optimization
833 Enable machine specific peephole optimizations
836 Common Report Var(flag_peephole2) Optimization
837 Enable an RTL peephole pass before sched2
840 Common Report Var(flag_pic,2)
841 Generate position-independent code if possible (large mode)
844 Common Report Var(flag_pie,2)
845 Generate position-independent code for executables if possible (large mode)
848 Common Report Var(flag_pic,1) VarExists
849 Generate position-independent code if possible (small mode)
852 Common Report Var(flag_pie,1) VarExists
853 Generate position-independent code for executables if possible (small mode)
855 fpredictive-commoning
856 Common Report Var(flag_predictive_commoning) Optimization
857 Run predictive commoning optimization.
859 fprefetch-loop-arrays
860 Common Report Var(flag_prefetch_loop_arrays) Optimization
861 Generate prefetch instructions, if available, for arrays in loops
864 Common Report Var(profile_flag)
865 Enable basic program profiling code
868 Common Report Var(profile_arc_flag)
869 Insert arc-based program profiling code
872 Common Joined RejectNegative
873 Set the top-level directory for storing the profile data.
874 The default is 'pwd'.
877 Common Report Var(flag_profile_correction)
878 Enable correction of flow inconsistent profile data input
882 Enable common options for generating profile info for profile feedback directed optimizations
885 Common Joined RejectNegative
886 Enable common options for generating profile info for profile feedback directed optimizations, and set -fprofile-dir=
889 Common Var(flag_profile_use)
890 Enable common options for performing profile feedback directed optimizations
893 Common Joined RejectNegative
894 Enable common options for performing profile feedback directed optimizations, and set -fprofile-dir=
897 Common Report Var(flag_profile_values)
898 Insert code to profile values of expressions
904 Common Joined RejectNegative
905 -frandom-seed=<string> Make compile reproducible using <string>
907 ; This switch causes the command line that was used to create an
908 ; object file to be recorded into the object file. The exact format
909 ; of this recording is target and binary file format dependent.
910 ; It is related to the -fverbose-asm switch, but that switch only
911 ; records information in the assembler output file as comments, so
912 ; they never reach the object file.
914 Common Report Var(flag_record_gcc_switches)
915 Record gcc command line switches in the object file.
918 Common Report Var(flag_pcc_struct_return,0) VarExists Optimization
919 Return small aggregates in registers
922 Common Report Var(flag_regmove) Optimization
923 Enables a register move optimization
926 Common Report Var(flag_rename_registers) Init(2) Optimization
927 Perform a register renaming optimization pass
930 Common Report Var(flag_reorder_blocks) Optimization
931 Reorder basic blocks to improve code placement
933 freorder-blocks-and-partition
934 Common Report Var(flag_reorder_blocks_and_partition) Optimization
935 Reorder basic blocks and partition into hot and cold sections
938 Common Report Var(flag_reorder_functions) Optimization
939 Reorder functions to improve code placement
941 frerun-cse-after-loop
942 Common Report Var(flag_rerun_cse_after_loop) Init(2) Optimization
943 Add a common subexpression elimination pass after loop optimizations
947 Does nothing. Preserved for backward compatibility.
950 Common Report Var(flag_rounding_math) Optimization
951 Disable optimizations that assume default FP rounding behavior
954 Common Report Var(flag_schedule_interblock) Init(1) Optimization
955 Enable scheduling across basic blocks
958 Common Report Var(flag_schedule_speculative) Init(1) Optimization
959 Allow speculative motion of non-loads
962 Common Report Var(flag_schedule_speculative_load) Optimization
963 Allow speculative motion of some loads
965 fsched-spec-load-dangerous
966 Common Report Var(flag_schedule_speculative_load_dangerous) Optimization
967 Allow speculative motion of more loads
970 Common RejectNegative Joined
971 -fsched-verbose=<number> Set the verbosity level of the scheduler
973 fsched2-use-superblocks
974 Common Report Var(flag_sched2_use_superblocks) Optimization
975 If scheduling post reload, do superblock scheduling
978 Common Report Var(flag_sched2_use_traces) Optimization
979 If scheduling post reload, do trace scheduling
982 Common Report Var(flag_schedule_insns) Optimization
983 Reschedule instructions before register allocation
986 Common Report Var(flag_schedule_insns_after_reload) Optimization
987 Reschedule instructions after register allocation
989 ; This flag should be on when a target implements non-trivial
990 ; scheduling hooks, maybe saving some information for its own sake.
991 ; On IA64, for example, this is used for correct bundling.
992 fselective-scheduling
993 Common Report Var(flag_selective_scheduling) Optimization
994 Schedule instructions using selective scheduling algorithm
996 fselective-scheduling2
997 Common Report Var(flag_selective_scheduling2) Optimization
998 Run selective scheduling after reload
1000 fsel-sched-pipelining
1001 Common Report Var(flag_sel_sched_pipelining) Init(0) Optimization
1002 Perform software pipelining of inner loops during selective scheduling
1004 fsel-sched-pipelining-outer-loops
1005 Common Report Var(flag_sel_sched_pipelining_outer_loops) Init(0) Optimization
1006 Perform software pipelining of outer loops during selective scheduling
1008 fsel-sched-reschedule-pipelined
1009 Common Report Var(flag_sel_sched_reschedule_pipelined) Init(0) Optimization
1010 Reschedule pipelined regions without pipelining
1012 ; sched_stalled_insns means that insns can be moved prematurely from the queue
1013 ; of stalled insns into the ready list.
1014 fsched-stalled-insns
1015 Common Report Var(flag_sched_stalled_insns) Optimization UInteger
1016 Allow premature scheduling of queued insns
1018 fsched-stalled-insns=
1019 Common RejectNegative Joined UInteger
1020 -fsched-stalled-insns=<number> Set number of queued insns that can be prematurely scheduled
1022 ; sched_stalled_insns_dep controls how many recently scheduled cycles will
1023 ; be examined for a dependency on a stalled insn that is candidate for
1024 ; premature removal from the queue of stalled insns into the ready list (has
1025 ; an effect only if the flag 'sched_stalled_insns' is set).
1026 fsched-stalled-insns-dep
1027 Common Report Var(flag_sched_stalled_insns_dep,1) Init(1) Optimization UInteger
1028 Set dependence distance checking in premature scheduling of queued insns
1030 fsched-stalled-insns-dep=
1031 Common RejectNegative Joined UInteger
1032 -fsched-stalled-insns-dep=<number> Set dependence distance checking in premature scheduling of queued insns
1035 Common Report Var(flag_section_anchors) Optimization
1036 Access data in the same section from shared anchor points
1038 frtl-abstract-sequences
1039 Common Report Var(flag_rtl_seqabstr) Optimization
1040 Perform sequence abstraction optimization on RTL
1043 Common Report Var(flag_see) Init(0)
1044 Eliminate redundant sign extensions using LCM.
1047 Common C ObjC C++ ObjC++ Report Var(flag_show_column) Init(0)
1048 Show column numbers in diagnostics, when available. Default off
1051 Common Report Var(flag_signaling_nans) Optimization
1052 Disable optimizations observable by IEEE signaling NaNs
1055 Common Report Var(flag_signed_zeros) Init(1) Optimization
1056 Disable floating point optimizations that ignore the IEEE signedness of zero
1058 fsingle-precision-constant
1059 Common Report Var(flag_single_precision_constant) Optimization
1060 Convert floating point constants to single precision constants
1062 fsplit-ivs-in-unroller
1063 Common Report Var(flag_split_ivs_in_unroller) Init(1) Optimization
1064 Split lifetimes of induction variables when loops are unrolled
1067 Common Report Var(flag_split_wide_types) Optimization
1068 Split wide types into independent registers
1070 fvariable-expansion-in-unroller
1071 Common Report Var(flag_variable_expansion_in_unroller) Optimization
1072 Apply variable expansion when loops are unrolled
1075 Common Report RejectNegative Joined
1076 -fstack-check=[no|generic|specific] Insert stack checking code into the program
1080 Insert stack checking code into the program. Same as -fstack-check=specific
1085 fstack-limit-register=
1086 Common RejectNegative Joined
1087 -fstack-limit-register=<register> Trap if the stack goes past <register>
1089 fstack-limit-symbol=
1090 Common RejectNegative Joined
1091 -fstack-limit-symbol=<name> Trap if the stack goes past symbol <name>
1094 Common Report Var(flag_stack_protect, 1)
1095 Use propolice as a stack protection method
1097 fstack-protector-all
1098 Common Report RejectNegative Var(flag_stack_protect, 2) VarExists
1099 Use a stack protection method for every function
1103 Does nothing. Preserved for backward compatibility.
1105 ; Nonzero if we should do (language-dependent) alias analysis.
1106 ; Typically, this analysis will assume that expressions of certain
1107 ; types do not alias expressions of certain other types. Only used
1108 ; if alias analysis (in general) is enabled.
1110 Common Report Var(flag_strict_aliasing) Optimization
1111 Assume strict aliasing rules apply
1114 Common Report Var(flag_strict_overflow)
1115 Treat signed overflow as undefined
1118 Common Report Var(flag_syntax_only)
1119 Check for syntax errors, then stop
1122 Common Report Var(flag_test_coverage)
1123 Create data files needed by \"gcov\"
1126 Common Report Var(flag_thread_jumps) Optimization
1127 Perform jump threading optimizations
1130 Common Report Var(time_report)
1131 Report the time taken by each compiler pass
1134 Common Joined RejectNegative
1135 -ftls-model=[global-dynamic|local-dynamic|initial-exec|local-exec] Set the default thread-local storage code generation model
1138 Common Report Var(flag_toplevel_reorder) Init(2) Optimization
1139 Reorder top level functions, variables, and asms
1142 Common Report Var(flag_tracer)
1143 Perform superblock formation via tail duplication
1145 ; Zero means that floating-point math operations cannot generate a
1146 ; (user-visible) trap. This is the case, for example, in nonstop
1147 ; IEEE 754 arithmetic.
1149 Common Report Var(flag_trapping_math) Init(1) Optimization
1150 Assume floating-point operations can trap
1153 Common Report Var(flag_trapv) Optimization
1154 Trap for signed overflow in addition, subtraction and multiplication
1157 Common Report Var(flag_tree_ccp) Optimization
1158 Enable SSA-CCP optimization on trees
1162 Does nothing. Preserved for backward compatibility.
1165 Common Report Var(flag_tree_ch) Optimization
1166 Enable loop header copying on trees
1169 Common Report Var(flag_tree_copyrename) Optimization
1170 Replace SSA temporaries with better names in copies
1173 Common Report Var(flag_tree_copy_prop) Optimization
1174 Enable copy propagation on trees
1176 ftree-store-copy-prop
1178 Does nothing. Preserved for backward compatibility.
1181 Common Report Var(flag_tree_cselim) Init(2) Optimization
1182 Transform condition stores into unconditional ones
1184 ftree-switch-conversion
1185 Common Report Var(flag_tree_switch_conversion) Optimization
1186 Perform conversions of switch initializations.
1189 Common Report Var(flag_tree_dce) Optimization
1190 Enable SSA dead code elimination optimization on trees
1192 ftree-dominator-opts
1193 Common Report Var(flag_tree_dom) Optimization
1194 Enable dominator optimizations
1197 Common Report Var(flag_tree_dse) Optimization
1198 Enable dead store elimination
1201 Common Report Var(flag_tree_fre) Optimization
1202 Enable Full Redundancy Elimination (FRE) on trees
1204 ftree-loop-distribution
1205 Common Report Var(flag_tree_loop_distribution) Optimization
1206 Enable loop distribution on trees
1209 Common Report Var(flag_tree_loop_im) Init(1) Optimization
1210 Enable loop invariant motion on trees
1213 Common Report Var(flag_tree_loop_linear) Optimization
1214 Enable linear loop transforms on trees
1217 Common Report Var(flag_tree_loop_ivcanon) Init(1) Optimization
1218 Create canonical induction variables in loops
1221 Common Report Var(flag_tree_loop_optimize) Init(1) Optimization
1222 Enable loop optimizations on tree level
1224 ftree-parallelize-loops=
1225 Common Report Joined UInteger Var(flag_tree_parallelize_loops) Init(1)
1226 Enable automatic parallelization of loops
1229 Common Report Var(flag_tree_pre) Optimization
1230 Enable SSA-PRE optimization on trees
1233 Common Report Var(flag_tree_reassoc) Init(1) Optimization
1234 Enable reassociation on tree level
1238 Does nothing. Preserved for backward compatibility.
1241 Common Report Var(flag_tree_sink) Optimization
1242 Enable SSA code sinking on trees
1245 Common Report Var(flag_tree_sra) Optimization
1246 Perform scalar replacement of aggregates
1249 Common Report Var(flag_tree_ter) Init(1) Optimization
1250 Replace temporary expressions in the SSA->normal pass
1253 Common Report Var(flag_tree_live_range_split) Optimization
1254 Perform live range splitting during the SSA->normal pass
1257 Common Report Var(flag_tree_vrp) Init(0) Optimization
1258 Perform Value Range Propagation on trees
1261 Common Report Var(flag_unit_at_a_time) Init(1) Optimization
1262 Compile whole compilation unit at a time
1265 Common Report Var(flag_unroll_loops) Optimization
1266 Perform loop unrolling when iteration count is known
1269 Common Report Var(flag_unroll_all_loops) Optimization
1270 Perform loop unrolling for all loops
1272 ; Nonzero means that loop optimizer may assume that the induction variables
1273 ; that control loops do not overflow and that the loops with nontrivial
1274 ; exit condition are not infinite
1275 funsafe-loop-optimizations
1276 Common Report Var(flag_unsafe_loop_optimizations) Optimization
1277 Allow loop optimizations to assume that the loops behave in normal way
1280 Common Report Var(flag_associative_math)
1281 Allow optimization for floating-point arithmetic which may change the
1282 result of the operation due to rounding.
1285 Common Report Var(flag_reciprocal_math)
1286 Same as -fassociative-math for expressions which include division.
1288 ; Nonzero means that unsafe floating-point math optimizations are allowed
1289 ; for the sake of speed. IEEE compliance is not guaranteed, and operations
1290 ; are allowed to assume that their arguments and results are "normal"
1291 ; (e.g., nonnegative for SQRT).
1292 funsafe-math-optimizations
1293 Common Report Var(flag_unsafe_math_optimizations) Optimization
1294 Allow math optimizations that may violate IEEE or ISO standards
1297 Common Report Var(flag_unswitch_loops) Optimization
1298 Perform loop unswitching
1301 Common Report Var(flag_unwind_tables) Optimization
1302 Just generate unwind tables for exception handling
1305 Common Report Var(flag_var_tracking) VarExists Optimization
1306 Perform variable tracking
1308 fvar-tracking-uninit
1309 Common Report Var(flag_var_tracking_uninit) Optimization
1310 Perform variable tracking and also tag variables that are uninitialized
1313 Common Report Var(flag_tree_vectorize) Optimization
1314 Enable loop vectorization on trees
1317 Common Report Var(flag_vect_cost_model) Optimization
1318 Enable use of cost model in vectorization
1320 ftree-vect-loop-version
1321 Common Report Var(flag_tree_vect_loop_version) Init(1) Optimization
1322 Enable loop versioning when doing loop vectorization on trees
1324 ftree-vectorizer-verbose=
1325 Common RejectNegative Joined
1326 -ftree-vectorizer-verbose=<number> Set the verbosity level of the vectorizer
1329 Common Report Var(flag_tree_scev_cprop) Init(1) Optimization
1330 Enable copy propagation of scalar-evolution information.
1332 ; -fverbose-asm causes extra commentary information to be produced in
1333 ; the generated assembly code (to make it more readable). This option
1334 ; is generally only of use to those who actually need to read the
1335 ; generated assembly code (perhaps while debugging the compiler itself).
1336 ; -fno-verbose-asm, the default, causes the extra information
1337 ; to not be added and is useful when comparing two assembler files.
1339 Common Report Var(flag_verbose_asm)
1340 Add extra commentary to assembler output
1343 Common Joined RejectNegative
1344 -fvisibility=[default|internal|hidden|protected] Set the default symbol visibility
1348 Common Report Var(flag_value_profile_transformations) Optimization
1349 Use expression value profiles in optimizations
1352 Common Report Var(flag_web) Init(2) Optimization
1353 Construct webs and split unrelated uses of single variable
1355 ftree-builtin-call-dce
1356 Common Report Var(flag_tree_builtin_call_dce) Init(0) Optimization
1357 Enable conditional dead code elimination for builtin calls
1360 Common Report Var(flag_whole_program) Init(0) Optimization
1361 Perform whole program optimizations
1364 Common Report Var(flag_wrapv) Optimization
1365 Assume signed arithmetic overflow wraps around
1367 fzero-initialized-in-bss
1368 Common Report Var(flag_zero_initialized_in_bss) Init(1)
1369 Put zero initialized data in the bss section
1372 Common JoinedOrMissing
1373 Generate debug information in default format
1376 Common JoinedOrMissing Negative(gdwarf-2)
1377 Generate debug information in COFF format
1380 Common JoinedOrMissing Negative(gstabs)
1381 Generate debug information in DWARF v2 format
1384 Common JoinedOrMissing
1385 Generate debug information in default extended format
1388 Common JoinedOrMissing Negative(gstabs+)
1389 Generate debug information in STABS format
1392 Common JoinedOrMissing Negative(gvms)
1393 Generate debug information in extended STABS format
1396 Common JoinedOrMissing Negative(gxcoff)
1397 Generate debug information in VMS format
1400 Common JoinedOrMissing Negative(gxcoff+)
1401 Generate debug information in XCOFF format
1404 Common JoinedOrMissing Negative(gcoff)
1405 Generate debug information in extended XCOFF format
1408 Common Joined Separate
1409 -o <file> Place output into <file>
1412 Common Var(profile_flag)
1413 Enable function profiling
1416 Common Var(pedantic)
1417 Issue warnings needed for strict compliance to the standard
1421 Like -pedantic but issue them as errors
1424 Common Var(quiet_flag)
1425 Do not display functions compiled or elapsed time
1428 Common Var(version_flag)
1429 Display the compiler's version
1432 Common Var(inhibit_warnings)
1436 Common RejectNegative Negative(pie)
1437 Create a shared library
1440 Common RejectNegative Negative(shared)
1441 Create a position independent executable
1443 ; This comment is to ensure we retain the blank line above.