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
570 fguess-branch-probability
571 Common Report Var(flag_guess_branch_prob) Optimization
572 Enable guessing of branch probabilities
574 ; Nonzero means ignore `#ident' directives. 0 means handle them.
575 ; Generate position-independent code for executables if possible
576 ; On SVR4 targets, it also controls whether or not to emit a
577 ; string identifying the compiler.
579 Common Report Var(flag_no_ident,0)
580 Process #ident directives
583 Common Report Var(flag_if_conversion) Optimization
584 Perform conversion of conditional jumps to branchless equivalents
587 Common Report Var(flag_if_conversion2) Optimization
588 Perform conversion of conditional jumps to conditional execution
590 ; -finhibit-size-directive inhibits output of .size for ELF.
591 ; This is used only for compiling crtstuff.c,
592 ; and it may be extended to other effects
593 ; needed for crtstuff.c on other systems.
594 finhibit-size-directive
595 Common Report Var(flag_inhibit_size_directive)
596 Do not generate .size directives
599 Common Report Var(flag_indirect_inlining)
600 Perform indirect inlining
602 ; Nonzero means that functions declared `inline' will be treated
603 ; as `static'. Prevents generation of zillions of copies of unused
604 ; static inline functions; instead, `inlines' are written out
605 ; only when actually used. Used in conjunction with -g. Also
606 ; does the right thing with #pragma interface.
608 Common Report Var(flag_no_inline,0) Init(0)
609 Pay attention to the \"inline\" keyword
611 finline-small-functions
612 Common Report Var(flag_inline_small_functions) Optimization
613 Integrate simple functions into their callers when code size is known to not growth
616 Common Report Var(flag_inline_functions) Optimization
617 Integrate simple functions into their callers
619 finline-functions-called-once
620 Common Report Var(flag_inline_functions_called_once) Init(1) Optimization
621 Integrate functions called once into their callers
624 Common RejectNegative Joined UInteger
627 Common RejectNegative Joined UInteger
628 -finline-limit=<number> Limit the size of inlined functions to <number>
630 finstrument-functions
631 Common Report Var(flag_instrument_function_entry_exit)
632 Instrument function entry and exit with profiling calls
634 finstrument-functions-exclude-function-list=
635 Common RejectNegative Joined
636 -finstrument-functions-exclude-function-list=name,... Do not instrument listed functions
638 finstrument-functions-exclude-file-list=
639 Common RejectNegative Joined
640 -finstrument-functions-exclude-file-list=filename,... Do not instrument functions listed in files
643 Common Report Var(flag_ipa_cp) Optimization
644 Perform Interprocedural constant propagation
647 Common Report Var(flag_ipa_cp_clone) Optimization
648 Perform cloning to make Interprocedural constant propagation stronger
651 Common Report Var(flag_ipa_pure_const) Init(0) Optimization
652 Discover pure and const functions
655 Common Report Var(flag_ipa_pta) Init(0) Optimization
656 Perform interprocedural points-to analysis
659 Common Report Var(flag_ipa_reference) Init(0) Optimization
660 Discover readonly and non addressable static variables
663 Common Report Var(flag_ipa_type_escape) Init(0) Optimization
664 Type based escape and alias analysis
667 Common Report Var(flag_ipa_matrix_reorg) Optimization
668 Perform matrix layout flattening and transposing based
669 on profiling information.
672 Common Report Var(flag_ipa_struct_reorg)
673 Perform structure layout optimizations based
674 on profiling information.
677 Common Report Var(flag_ira) Init(0)
678 Use integrated register allocator.
681 Common Joined RejectNegative
682 -fira-algorithm=[regional|CB|mixed] Set the used IRA algorithm
685 Common Report Var(flag_ira_coalesce) Init(0)
686 Do optimistic coalescing.
688 fira-share-save-slots
689 Common Report Var(flag_ira_share_save_slots) Init(1)
690 Share slots for saving different hard registers.
692 fira-share-spill-slots
693 Common Report Var(flag_ira_share_spill_slots) Init(1)
694 Share stack slots for spilled pseudo-registers.
697 Common RejectNegative Joined UInteger
698 -fira-verbose=<number> Control IRA's level of diagnostic messages.
701 Common Report Var(flag_ivopts) Init(1) Optimization
702 Optimize induction variables on trees
705 Common Var(flag_jump_tables) Init(1) Optimization
706 Use jump tables for sufficiently large switch statements
708 fkeep-inline-functions
709 Common Report Var(flag_keep_inline_functions)
710 Generate code for functions even if they are fully inlined
713 Common Report Var(flag_keep_static_consts) Init(1)
714 Emit static const variables even if they are not used
717 Common Report Var(flag_leading_underscore) Init(-1)
718 Give external symbols a leading underscore
722 Does nothing. Preserved for backward compatibility.
725 Common Report Var(flag_errno_math) Init(1) Optimization
726 Set errno after built-in math functions
729 Common Report Var(mem_report)
730 Report on permanent memory allocation
732 ; This will attempt to merge constant section constants, if 1 only
733 ; string constants and constants from constant pool, if 2 also constant
736 Common Report Var(flag_merge_constants,2) Init(1) Optimization
737 Attempt to merge identical constants and constant variables
740 Common Report Var(flag_merge_constants,1) VarExists Optimization
741 Attempt to merge identical constants across compilation units
744 Common Report Var(flag_merge_debug_strings) Init(1)
745 Attempt to merge identical debug strings across compilation units
748 Common RejectNegative Joined UInteger
749 -fmessage-length=<number> Limit diagnostics to <number> characters per line. 0 suppresses line-wrapping
752 Common Report Var(flag_modulo_sched) Optimization
753 Perform SMS based modulo scheduling before the first scheduling pass
755 fmodulo-sched-allow-regmoves
756 Common Report Var(flag_modulo_sched_allow_regmoves)
757 Perform SMS based modulo scheduling with register moves allowed
759 fmove-loop-invariants
760 Common Report Var(flag_move_loop_invariants) Init(1) Optimization
761 Move loop invariant computations out of loops
764 Common RejectNegative Report Var(flag_mudflap)
765 Add mudflap bounds-checking instrumentation for single-threaded program
768 Common RejectNegative Report VarExists Var(flag_mudflap,2)
769 Add mudflap bounds-checking instrumentation for multi-threaded program
772 Common RejectNegative Report Var(flag_mudflap_ignore_reads)
773 Ignore read operations when inserting mudflap instrumentation
776 Common Var(flag_dce) Init(1) Optimization
777 Use the RTL dead code elimination pass
780 Common Var(flag_dse) Init(1) Optimization
781 Use the RTL dead store elimination pass
783 freschedule-modulo-scheduled-loops
784 Common Report Var(flag_resched_modulo_sched) Optimization
785 Enable/Disable the traditional scheduling in loops that already passed modulo scheduling
788 Common Report Var(flag_non_call_exceptions) Optimization
789 Support synchronous non-call exceptions
792 Common Report Var(flag_omit_frame_pointer) Optimization
793 When possible do not generate stack frames
795 foptimize-register-move
796 Common Report Var(flag_regmove) Optimization
797 Do the full register move optimization pass
799 foptimize-sibling-calls
800 Common Report Var(flag_optimize_sibling_calls) Optimization
801 Optimize sibling and tail recursive calls
804 Common Report Var(pre_ipa_mem_report)
805 Report on memory allocation before interprocedural optimization
808 Common Report Var(post_ipa_mem_report)
809 Report on memory allocation before interprocedural optimization
812 Common Report Var(flag_pack_struct) Optimization
813 Pack structure members together without holes
816 Common RejectNegative Joined UInteger Optimization
817 -fpack-struct=<number> Set initial maximum structure member alignment
820 Common Report Var(flag_pcc_struct_return,1) VarExists
821 Return small aggregates in memory, not registers
824 Common Report Var(flag_peel_loops) Optimization
828 Common Report Var(flag_no_peephole,0) Optimization
829 Enable machine specific peephole optimizations
832 Common Report Var(flag_peephole2) Optimization
833 Enable an RTL peephole pass before sched2
836 Common Report Var(flag_pic,2)
837 Generate position-independent code if possible (large mode)
840 Common Report Var(flag_pie,2)
841 Generate position-independent code for executables if possible (large mode)
844 Common Report Var(flag_pic,1) VarExists
845 Generate position-independent code if possible (small mode)
848 Common Report Var(flag_pie,1) VarExists
849 Generate position-independent code for executables if possible (small mode)
851 fpredictive-commoning
852 Common Report Var(flag_predictive_commoning) Optimization
853 Run predictive commoning optimization.
855 fprefetch-loop-arrays
856 Common Report Var(flag_prefetch_loop_arrays) Optimization
857 Generate prefetch instructions, if available, for arrays in loops
860 Common Report Var(profile_flag)
861 Enable basic program profiling code
864 Common Report Var(profile_arc_flag)
865 Insert arc-based program profiling code
868 Common Joined RejectNegative
869 Set the top-level directory for storing the profile data.
870 The default is 'pwd'.
873 Common Report Var(flag_profile_correction)
874 Enable correction of flow inconsistent profile data input
878 Enable common options for generating profile info for profile feedback directed optimizations
881 Common Joined RejectNegative
882 Enable common options for generating profile info for profile feedback directed optimizations, and set -fprofile-dir=
885 Common Var(flag_profile_use)
886 Enable common options for performing profile feedback directed optimizations
889 Common Joined RejectNegative
890 Enable common options for performing profile feedback directed optimizations, and set -fprofile-dir=
893 Common Report Var(flag_profile_values)
894 Insert code to profile values of expressions
900 Common Joined RejectNegative
901 -frandom-seed=<string> Make compile reproducible using <string>
903 ; This switch causes the command line that was used to create an
904 ; object file to be recorded into the object file. The exact format
905 ; of this recording is target and binary file format dependent.
906 ; It is related to the -fverbose-asm switch, but that switch only
907 ; records information in the assembler output file as comments, so
908 ; they never reach the object file.
910 Common Report Var(flag_record_gcc_switches)
911 Record gcc command line switches in the object file.
914 Common Report Var(flag_pcc_struct_return,0) VarExists Optimization
915 Return small aggregates in registers
918 Common Report Var(flag_regmove) Optimization
919 Enables a register move optimization
922 Common Report Var(flag_rename_registers) Init(2) Optimization
923 Perform a register renaming optimization pass
926 Common Report Var(flag_reorder_blocks) Optimization
927 Reorder basic blocks to improve code placement
929 freorder-blocks-and-partition
930 Common Report Var(flag_reorder_blocks_and_partition) Optimization
931 Reorder basic blocks and partition into hot and cold sections
934 Common Report Var(flag_reorder_functions) Optimization
935 Reorder functions to improve code placement
937 frerun-cse-after-loop
938 Common Report Var(flag_rerun_cse_after_loop) Init(2) Optimization
939 Add a common subexpression elimination pass after loop optimizations
943 Does nothing. Preserved for backward compatibility.
946 Common Report Var(flag_rounding_math) Optimization
947 Disable optimizations that assume default FP rounding behavior
950 Common Report Var(flag_schedule_interblock) Init(1) Optimization
951 Enable scheduling across basic blocks
954 Common Report Var(flag_schedule_speculative) Init(1) Optimization
955 Allow speculative motion of non-loads
958 Common Report Var(flag_schedule_speculative_load) Optimization
959 Allow speculative motion of some loads
961 fsched-spec-load-dangerous
962 Common Report Var(flag_schedule_speculative_load_dangerous) Optimization
963 Allow speculative motion of more loads
966 Common RejectNegative Joined
967 -fsched-verbose=<number> Set the verbosity level of the scheduler
969 fsched2-use-superblocks
970 Common Report Var(flag_sched2_use_superblocks) Optimization
971 If scheduling post reload, do superblock scheduling
974 Common Report Var(flag_sched2_use_traces) Optimization
975 If scheduling post reload, do trace scheduling
978 Common Report Var(flag_schedule_insns) Optimization
979 Reschedule instructions before register allocation
982 Common Report Var(flag_schedule_insns_after_reload) Optimization
983 Reschedule instructions after register allocation
985 ; This flag should be on when a target implements non-trivial
986 ; scheduling hooks, maybe saving some information for its own sake.
987 ; On IA64, for example, this is used for correct bundling.
988 fselective-scheduling
989 Common Report Var(flag_selective_scheduling) Optimization
990 Schedule instructions using selective scheduling algorithm
992 fselective-scheduling2
993 Common Report Var(flag_selective_scheduling2) Optimization
994 Run selective scheduling after reload
996 fsel-sched-pipelining
997 Common Report Var(flag_sel_sched_pipelining) Init(0) Optimization
998 Perform software pipelining of inner loops during selective scheduling
1000 fsel-sched-pipelining-outer-loops
1001 Common Report Var(flag_sel_sched_pipelining_outer_loops) Init(0) Optimization
1002 Perform software pipelining of outer loops during selective scheduling
1004 fsel-sched-reschedule-pipelined
1005 Common Report Var(flag_sel_sched_reschedule_pipelined) Init(0) Optimization
1006 Reschedule pipelined regions without pipelining
1008 ; sched_stalled_insns means that insns can be moved prematurely from the queue
1009 ; of stalled insns into the ready list.
1010 fsched-stalled-insns
1011 Common Report Var(flag_sched_stalled_insns) Optimization UInteger
1012 Allow premature scheduling of queued insns
1014 fsched-stalled-insns=
1015 Common RejectNegative Joined UInteger
1016 -fsched-stalled-insns=<number> Set number of queued insns that can be prematurely scheduled
1018 ; sched_stalled_insns_dep controls how many recently scheduled cycles will
1019 ; be examined for a dependency on a stalled insn that is candidate for
1020 ; premature removal from the queue of stalled insns into the ready list (has
1021 ; an effect only if the flag 'sched_stalled_insns' is set).
1022 fsched-stalled-insns-dep
1023 Common Report Var(flag_sched_stalled_insns_dep,1) Init(1) Optimization UInteger
1024 Set dependence distance checking in premature scheduling of queued insns
1026 fsched-stalled-insns-dep=
1027 Common RejectNegative Joined UInteger
1028 -fsched-stalled-insns-dep=<number> Set dependence distance checking in premature scheduling of queued insns
1031 Common Report Var(flag_section_anchors) Optimization
1032 Access data in the same section from shared anchor points
1034 frtl-abstract-sequences
1035 Common Report Var(flag_rtl_seqabstr) Optimization
1036 Perform sequence abstraction optimization on RTL
1039 Common Report Var(flag_see) Init(0)
1040 Eliminate redundant sign extensions using LCM.
1043 Common C ObjC C++ ObjC++ Report Var(flag_show_column) Init(0)
1044 Show column numbers in diagnostics, when available. Default off
1047 Common Report Var(flag_signaling_nans) Optimization
1048 Disable optimizations observable by IEEE signaling NaNs
1051 Common Report Var(flag_signed_zeros) Init(1) Optimization
1052 Disable floating point optimizations that ignore the IEEE signedness of zero
1054 fsingle-precision-constant
1055 Common Report Var(flag_single_precision_constant) Optimization
1056 Convert floating point constants to single precision constants
1058 fsplit-ivs-in-unroller
1059 Common Report Var(flag_split_ivs_in_unroller) Init(1) Optimization
1060 Split lifetimes of induction variables when loops are unrolled
1063 Common Report Var(flag_split_wide_types) Optimization
1064 Split wide types into independent registers
1066 fvariable-expansion-in-unroller
1067 Common Report Var(flag_variable_expansion_in_unroller) Optimization
1068 Apply variable expansion when loops are unrolled
1071 Common Report RejectNegative Joined
1072 -fstack-check=[no|generic|specific] Insert stack checking code into the program
1076 Insert stack checking code into the program. Same as -fstack-check=specific
1081 fstack-limit-register=
1082 Common RejectNegative Joined
1083 -fstack-limit-register=<register> Trap if the stack goes past <register>
1085 fstack-limit-symbol=
1086 Common RejectNegative Joined
1087 -fstack-limit-symbol=<name> Trap if the stack goes past symbol <name>
1090 Common Report Var(flag_stack_protect, 1)
1091 Use propolice as a stack protection method
1093 fstack-protector-all
1094 Common Report RejectNegative Var(flag_stack_protect, 2) VarExists
1095 Use a stack protection method for every function
1099 Does nothing. Preserved for backward compatibility.
1101 ; Nonzero if we should do (language-dependent) alias analysis.
1102 ; Typically, this analysis will assume that expressions of certain
1103 ; types do not alias expressions of certain other types. Only used
1104 ; if alias analysis (in general) is enabled.
1106 Common Report Var(flag_strict_aliasing) Optimization
1107 Assume strict aliasing rules apply
1110 Common Report Var(flag_strict_overflow)
1111 Treat signed overflow as undefined
1114 Common Report Var(flag_syntax_only)
1115 Check for syntax errors, then stop
1118 Common Report Var(flag_test_coverage)
1119 Create data files needed by \"gcov\"
1122 Common Report Var(flag_thread_jumps) Optimization
1123 Perform jump threading optimizations
1126 Common Report Var(time_report)
1127 Report the time taken by each compiler pass
1130 Common Joined RejectNegative
1131 -ftls-model=[global-dynamic|local-dynamic|initial-exec|local-exec] Set the default thread-local storage code generation model
1134 Common Report Var(flag_toplevel_reorder) Init(2) Optimization
1135 Reorder top level functions, variables, and asms
1138 Common Report Var(flag_tracer)
1139 Perform superblock formation via tail duplication
1141 ; Zero means that floating-point math operations cannot generate a
1142 ; (user-visible) trap. This is the case, for example, in nonstop
1143 ; IEEE 754 arithmetic.
1145 Common Report Var(flag_trapping_math) Init(1) Optimization
1146 Assume floating-point operations can trap
1149 Common Report Var(flag_trapv) Optimization
1150 Trap for signed overflow in addition, subtraction and multiplication
1153 Common Report Var(flag_tree_ccp) Optimization
1154 Enable SSA-CCP optimization on trees
1158 Does nothing. Preserved for backward compatibility.
1161 Common Report Var(flag_tree_ch) Optimization
1162 Enable loop header copying on trees
1165 Common Report Var(flag_tree_copyrename) Optimization
1166 Replace SSA temporaries with better names in copies
1169 Common Report Var(flag_tree_copy_prop) Optimization
1170 Enable copy propagation on trees
1172 ftree-store-copy-prop
1174 Does nothing. Preserved for backward compatibility.
1177 Common Report Var(flag_tree_cselim) Init(2) Optimization
1178 Transform condition stores into unconditional ones
1180 ftree-switch-conversion
1181 Common Report Var(flag_tree_switch_conversion) Optimization
1182 Perform conversions of switch initializations.
1185 Common Report Var(flag_tree_dce) Optimization
1186 Enable SSA dead code elimination optimization on trees
1188 ftree-dominator-opts
1189 Common Report Var(flag_tree_dom) Optimization
1190 Enable dominator optimizations
1193 Common Report Var(flag_tree_dse) Optimization
1194 Enable dead store elimination
1197 Common Report Var(flag_tree_fre) Optimization
1198 Enable Full Redundancy Elimination (FRE) on trees
1200 ftree-loop-distribution
1201 Common Report Var(flag_tree_loop_distribution) Optimization
1202 Enable loop distribution on trees
1205 Common Report Var(flag_tree_loop_im) Init(1) Optimization
1206 Enable loop invariant motion on trees
1209 Common Report Var(flag_tree_loop_linear) Optimization
1210 Enable linear loop transforms on trees
1213 Common Report Var(flag_tree_loop_ivcanon) Init(1) Optimization
1214 Create canonical induction variables in loops
1217 Common Report Var(flag_tree_loop_optimize) Init(1) Optimization
1218 Enable loop optimizations on tree level
1220 ftree-parallelize-loops=
1221 Common Report Joined UInteger Var(flag_tree_parallelize_loops) Init(1)
1222 Enable automatic parallelization of loops
1225 Common Report Var(flag_tree_pre) Optimization
1226 Enable SSA-PRE optimization on trees
1229 Common Report Var(flag_tree_reassoc) Init(1) Optimization
1230 Enable reassociation on tree level
1234 Does nothing. Preserved for backward compatibility.
1237 Common Report Var(flag_tree_sink) Optimization
1238 Enable SSA code sinking on trees
1241 Common Report Var(flag_tree_sra) Optimization
1242 Perform scalar replacement of aggregates
1245 Common Report Var(flag_tree_ter) Init(1) Optimization
1246 Replace temporary expressions in the SSA->normal pass
1249 Common Report Var(flag_tree_live_range_split) Optimization
1250 Perform live range splitting during the SSA->normal pass
1253 Common Report Var(flag_tree_vrp) Init(0) Optimization
1254 Perform Value Range Propagation on trees
1257 Common Report Var(flag_unit_at_a_time) Init(1) Optimization
1258 Compile whole compilation unit at a time
1261 Common Report Var(flag_unroll_loops) Optimization
1262 Perform loop unrolling when iteration count is known
1265 Common Report Var(flag_unroll_all_loops) Optimization
1266 Perform loop unrolling for all loops
1268 ; Nonzero means that loop optimizer may assume that the induction variables
1269 ; that control loops do not overflow and that the loops with nontrivial
1270 ; exit condition are not infinite
1271 funsafe-loop-optimizations
1272 Common Report Var(flag_unsafe_loop_optimizations) Optimization
1273 Allow loop optimizations to assume that the loops behave in normal way
1276 Common Report Var(flag_associative_math)
1277 Allow optimization for floating-point arithmetic which may change the
1278 result of the operation due to rounding.
1281 Common Report Var(flag_reciprocal_math)
1282 Same as -fassociative-math for expressions which include division.
1284 ; Nonzero means that unsafe floating-point math optimizations are allowed
1285 ; for the sake of speed. IEEE compliance is not guaranteed, and operations
1286 ; are allowed to assume that their arguments and results are "normal"
1287 ; (e.g., nonnegative for SQRT).
1288 funsafe-math-optimizations
1289 Common Report Var(flag_unsafe_math_optimizations) Optimization
1290 Allow math optimizations that may violate IEEE or ISO standards
1293 Common Report Var(flag_unswitch_loops) Optimization
1294 Perform loop unswitching
1297 Common Report Var(flag_unwind_tables) Optimization
1298 Just generate unwind tables for exception handling
1301 Common Report Var(flag_var_tracking) VarExists Optimization
1302 Perform variable tracking
1304 fvar-tracking-uninit
1305 Common Report Var(flag_var_tracking_uninit) Optimization
1306 Perform variable tracking and also tag variables that are uninitialized
1309 Common Report Var(flag_tree_vectorize) Optimization
1310 Enable loop vectorization on trees
1313 Common Report Var(flag_vect_cost_model) Optimization
1314 Enable use of cost model in vectorization
1316 ftree-vect-loop-version
1317 Common Report Var(flag_tree_vect_loop_version) Init(1) Optimization
1318 Enable loop versioning when doing loop vectorization on trees
1320 ftree-vectorizer-verbose=
1321 Common RejectNegative Joined
1322 -ftree-vectorizer-verbose=<number> Set the verbosity level of the vectorizer
1325 Common Report Var(flag_tree_scev_cprop) Init(1) Optimization
1326 Enable copy propagation of scalar-evolution information.
1328 ; -fverbose-asm causes extra commentary information to be produced in
1329 ; the generated assembly code (to make it more readable). This option
1330 ; is generally only of use to those who actually need to read the
1331 ; generated assembly code (perhaps while debugging the compiler itself).
1332 ; -fno-verbose-asm, the default, causes the extra information
1333 ; to not be added and is useful when comparing two assembler files.
1335 Common Report Var(flag_verbose_asm)
1336 Add extra commentary to assembler output
1339 Common Joined RejectNegative
1340 -fvisibility=[default|internal|hidden|protected] Set the default symbol visibility
1344 Common Report Var(flag_value_profile_transformations) Optimization
1345 Use expression value profiles in optimizations
1348 Common Report Var(flag_web) Init(2) Optimization
1349 Construct webs and split unrelated uses of single variable
1351 ftree-builtin-call-dce
1352 Common Report Var(flag_tree_builtin_call_dce) Init(0) Optimization
1353 Enable conditional dead code elimination for builtin calls
1356 Common Report Var(flag_whole_program) Init(0) Optimization
1357 Perform whole program optimizations
1360 Common Report Var(flag_wrapv) Optimization
1361 Assume signed arithmetic overflow wraps around
1363 fzero-initialized-in-bss
1364 Common Report Var(flag_zero_initialized_in_bss) Init(1)
1365 Put zero initialized data in the bss section
1368 Common JoinedOrMissing
1369 Generate debug information in default format
1372 Common JoinedOrMissing Negative(gdwarf-2)
1373 Generate debug information in COFF format
1376 Common JoinedOrMissing Negative(gstabs)
1377 Generate debug information in DWARF v2 format
1380 Common JoinedOrMissing
1381 Generate debug information in default extended format
1384 Common JoinedOrMissing Negative(gstabs+)
1385 Generate debug information in STABS format
1388 Common JoinedOrMissing Negative(gvms)
1389 Generate debug information in extended STABS format
1392 Common JoinedOrMissing Negative(gxcoff)
1393 Generate debug information in VMS format
1396 Common JoinedOrMissing Negative(gxcoff+)
1397 Generate debug information in XCOFF format
1400 Common JoinedOrMissing Negative(gcoff)
1401 Generate debug information in extended XCOFF format
1404 Common Joined Separate
1405 -o <file> Place output into <file>
1408 Common Var(profile_flag)
1409 Enable function profiling
1412 Common Var(pedantic)
1413 Issue warnings needed for strict compliance to the standard
1417 Like -pedantic but issue them as errors
1420 Common Var(quiet_flag)
1421 Do not display functions compiled or elapsed time
1424 Common Var(version_flag)
1425 Display the compiler's version
1428 Common Var(inhibit_warnings)
1432 Common RejectNegative Negative(pie)
1433 Create a shared library
1436 Common RejectNegative Negative(shared)
1437 Create a position independent executable
1439 ; This comment is to ensure we retain the blank line above.