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=[CB|priority] Set the used IRA algorithm
689 Common Joined RejectNegative
690 -fira-region=[one|all|mixed] Set regions for IRA
693 Common Report Var(flag_ira_coalesce) Init(0)
694 Do optimistic coalescing.
696 fira-share-save-slots
697 Common Report Var(flag_ira_share_save_slots) Init(1)
698 Share slots for saving different hard registers.
700 fira-share-spill-slots
701 Common Report Var(flag_ira_share_spill_slots) Init(1)
702 Share stack slots for spilled pseudo-registers.
705 Common RejectNegative Joined UInteger
706 -fira-verbose=<number> Control IRA's level of diagnostic messages.
709 Common Report Var(flag_ivopts) Init(1) Optimization
710 Optimize induction variables on trees
713 Common Var(flag_jump_tables) Init(1) Optimization
714 Use jump tables for sufficiently large switch statements
716 fkeep-inline-functions
717 Common Report Var(flag_keep_inline_functions)
718 Generate code for functions even if they are fully inlined
721 Common Report Var(flag_keep_static_consts) Init(1)
722 Emit static const variables even if they are not used
725 Common Report Var(flag_leading_underscore) Init(-1)
726 Give external symbols a leading underscore
730 Does nothing. Preserved for backward compatibility.
733 Common Report Var(flag_errno_math) Init(1) Optimization
734 Set errno after built-in math functions
737 Common Report Var(mem_report)
738 Report on permanent memory allocation
740 ; This will attempt to merge constant section constants, if 1 only
741 ; string constants and constants from constant pool, if 2 also constant
744 Common Report Var(flag_merge_constants,2) Init(1) Optimization
745 Attempt to merge identical constants and constant variables
748 Common Report Var(flag_merge_constants,1) VarExists Optimization
749 Attempt to merge identical constants across compilation units
752 Common Report Var(flag_merge_debug_strings) Init(1)
753 Attempt to merge identical debug strings across compilation units
756 Common RejectNegative Joined UInteger
757 -fmessage-length=<number> Limit diagnostics to <number> characters per line. 0 suppresses line-wrapping
760 Common Report Var(flag_modulo_sched) Optimization
761 Perform SMS based modulo scheduling before the first scheduling pass
763 fmodulo-sched-allow-regmoves
764 Common Report Var(flag_modulo_sched_allow_regmoves)
765 Perform SMS based modulo scheduling with register moves allowed
767 fmove-loop-invariants
768 Common Report Var(flag_move_loop_invariants) Init(1) Optimization
769 Move loop invariant computations out of loops
772 Common RejectNegative Report Var(flag_mudflap)
773 Add mudflap bounds-checking instrumentation for single-threaded program
776 Common RejectNegative Report VarExists Var(flag_mudflap,2)
777 Add mudflap bounds-checking instrumentation for multi-threaded program
780 Common RejectNegative Report Var(flag_mudflap_ignore_reads)
781 Ignore read operations when inserting mudflap instrumentation
784 Common Var(flag_dce) Init(1) Optimization
785 Use the RTL dead code elimination pass
788 Common Var(flag_dse) Init(1) Optimization
789 Use the RTL dead store elimination pass
791 freschedule-modulo-scheduled-loops
792 Common Report Var(flag_resched_modulo_sched) Optimization
793 Enable/Disable the traditional scheduling in loops that already passed modulo scheduling
796 Common Report Var(flag_non_call_exceptions) Optimization
797 Support synchronous non-call exceptions
800 Common Report Var(flag_omit_frame_pointer) Optimization
801 When possible do not generate stack frames
803 foptimize-register-move
804 Common Report Var(flag_regmove) Optimization
805 Do the full register move optimization pass
807 foptimize-sibling-calls
808 Common Report Var(flag_optimize_sibling_calls) Optimization
809 Optimize sibling and tail recursive calls
812 Common Report Var(pre_ipa_mem_report)
813 Report on memory allocation before interprocedural optimization
816 Common Report Var(post_ipa_mem_report)
817 Report on memory allocation before interprocedural optimization
820 Common Report Var(flag_pack_struct) Optimization
821 Pack structure members together without holes
824 Common RejectNegative Joined UInteger Optimization
825 -fpack-struct=<number> Set initial maximum structure member alignment
828 Common Report Var(flag_pcc_struct_return,1) VarExists
829 Return small aggregates in memory, not registers
832 Common Report Var(flag_peel_loops) Optimization
836 Common Report Var(flag_no_peephole,0) Optimization
837 Enable machine specific peephole optimizations
840 Common Report Var(flag_peephole2) Optimization
841 Enable an RTL peephole pass before sched2
844 Common Report Var(flag_pic,2)
845 Generate position-independent code if possible (large mode)
848 Common Report Var(flag_pie,2)
849 Generate position-independent code for executables if possible (large mode)
852 Common Report Var(flag_pic,1) VarExists
853 Generate position-independent code if possible (small mode)
856 Common Report Var(flag_pie,1) VarExists
857 Generate position-independent code for executables if possible (small mode)
859 fpredictive-commoning
860 Common Report Var(flag_predictive_commoning) Optimization
861 Run predictive commoning optimization.
863 fprefetch-loop-arrays
864 Common Report Var(flag_prefetch_loop_arrays) Optimization
865 Generate prefetch instructions, if available, for arrays in loops
868 Common Report Var(profile_flag)
869 Enable basic program profiling code
872 Common Report Var(profile_arc_flag)
873 Insert arc-based program profiling code
876 Common Joined RejectNegative
877 Set the top-level directory for storing the profile data.
878 The default is 'pwd'.
881 Common Report Var(flag_profile_correction)
882 Enable correction of flow inconsistent profile data input
886 Enable common options for generating profile info for profile feedback directed optimizations
889 Common Joined RejectNegative
890 Enable common options for generating profile info for profile feedback directed optimizations, and set -fprofile-dir=
893 Common Var(flag_profile_use)
894 Enable common options for performing profile feedback directed optimizations
897 Common Joined RejectNegative
898 Enable common options for performing profile feedback directed optimizations, and set -fprofile-dir=
901 Common Report Var(flag_profile_values)
902 Insert code to profile values of expressions
908 Common Joined RejectNegative
909 -frandom-seed=<string> Make compile reproducible using <string>
911 ; This switch causes the command line that was used to create an
912 ; object file to be recorded into the object file. The exact format
913 ; of this recording is target and binary file format dependent.
914 ; It is related to the -fverbose-asm switch, but that switch only
915 ; records information in the assembler output file as comments, so
916 ; they never reach the object file.
918 Common Report Var(flag_record_gcc_switches)
919 Record gcc command line switches in the object file.
922 Common Report Var(flag_pcc_struct_return,0) VarExists Optimization
923 Return small aggregates in registers
926 Common Report Var(flag_regmove) Optimization
927 Enables a register move optimization
930 Common Report Var(flag_rename_registers) Init(2) Optimization
931 Perform a register renaming optimization pass
934 Common Report Var(flag_reorder_blocks) Optimization
935 Reorder basic blocks to improve code placement
937 freorder-blocks-and-partition
938 Common Report Var(flag_reorder_blocks_and_partition) Optimization
939 Reorder basic blocks and partition into hot and cold sections
942 Common Report Var(flag_reorder_functions) Optimization
943 Reorder functions to improve code placement
945 frerun-cse-after-loop
946 Common Report Var(flag_rerun_cse_after_loop) Init(2) Optimization
947 Add a common subexpression elimination pass after loop optimizations
951 Does nothing. Preserved for backward compatibility.
954 Common Report Var(flag_rounding_math) Optimization
955 Disable optimizations that assume default FP rounding behavior
958 Common Report Var(flag_schedule_interblock) Init(1) Optimization
959 Enable scheduling across basic blocks
962 Common Report Var(flag_schedule_speculative) Init(1) Optimization
963 Allow speculative motion of non-loads
966 Common Report Var(flag_schedule_speculative_load) Optimization
967 Allow speculative motion of some loads
969 fsched-spec-load-dangerous
970 Common Report Var(flag_schedule_speculative_load_dangerous) Optimization
971 Allow speculative motion of more loads
974 Common RejectNegative Joined
975 -fsched-verbose=<number> Set the verbosity level of the scheduler
977 fsched2-use-superblocks
978 Common Report Var(flag_sched2_use_superblocks) Optimization
979 If scheduling post reload, do superblock scheduling
982 Common Report Var(flag_sched2_use_traces) Optimization
983 If scheduling post reload, do trace scheduling
986 Common Report Var(flag_schedule_insns) Optimization
987 Reschedule instructions before register allocation
990 Common Report Var(flag_schedule_insns_after_reload) Optimization
991 Reschedule instructions after register allocation
993 ; This flag should be on when a target implements non-trivial
994 ; scheduling hooks, maybe saving some information for its own sake.
995 ; On IA64, for example, this is used for correct bundling.
996 fselective-scheduling
997 Common Report Var(flag_selective_scheduling) Optimization
998 Schedule instructions using selective scheduling algorithm
1000 fselective-scheduling2
1001 Common Report Var(flag_selective_scheduling2) Optimization
1002 Run selective scheduling after reload
1004 fsel-sched-pipelining
1005 Common Report Var(flag_sel_sched_pipelining) Init(0) Optimization
1006 Perform software pipelining of inner loops during selective scheduling
1008 fsel-sched-pipelining-outer-loops
1009 Common Report Var(flag_sel_sched_pipelining_outer_loops) Init(0) Optimization
1010 Perform software pipelining of outer loops during selective scheduling
1012 fsel-sched-reschedule-pipelined
1013 Common Report Var(flag_sel_sched_reschedule_pipelined) Init(0) Optimization
1014 Reschedule pipelined regions without pipelining
1016 ; sched_stalled_insns means that insns can be moved prematurely from the queue
1017 ; of stalled insns into the ready list.
1018 fsched-stalled-insns
1019 Common Report Var(flag_sched_stalled_insns) Optimization UInteger
1020 Allow premature scheduling of queued insns
1022 fsched-stalled-insns=
1023 Common RejectNegative Joined UInteger
1024 -fsched-stalled-insns=<number> Set number of queued insns that can be prematurely scheduled
1026 ; sched_stalled_insns_dep controls how many recently scheduled cycles will
1027 ; be examined for a dependency on a stalled insn that is candidate for
1028 ; premature removal from the queue of stalled insns into the ready list (has
1029 ; an effect only if the flag 'sched_stalled_insns' is set).
1030 fsched-stalled-insns-dep
1031 Common Report Var(flag_sched_stalled_insns_dep,1) Init(1) Optimization UInteger
1032 Set dependence distance checking in premature scheduling of queued insns
1034 fsched-stalled-insns-dep=
1035 Common RejectNegative Joined UInteger
1036 -fsched-stalled-insns-dep=<number> Set dependence distance checking in premature scheduling of queued insns
1039 Common Report Var(flag_section_anchors) Optimization
1040 Access data in the same section from shared anchor points
1042 frtl-abstract-sequences
1043 Common Report Var(flag_rtl_seqabstr) Optimization
1044 Perform sequence abstraction optimization on RTL
1047 Common Report Var(flag_see) Init(0)
1048 Eliminate redundant sign extensions using LCM.
1051 Common C ObjC C++ ObjC++ Report Var(flag_show_column) Init(0)
1052 Show column numbers in diagnostics, when available. Default off
1055 Common Report Var(flag_signaling_nans) Optimization
1056 Disable optimizations observable by IEEE signaling NaNs
1059 Common Report Var(flag_signed_zeros) Init(1) Optimization
1060 Disable floating point optimizations that ignore the IEEE signedness of zero
1062 fsingle-precision-constant
1063 Common Report Var(flag_single_precision_constant) Optimization
1064 Convert floating point constants to single precision constants
1066 fsplit-ivs-in-unroller
1067 Common Report Var(flag_split_ivs_in_unroller) Init(1) Optimization
1068 Split lifetimes of induction variables when loops are unrolled
1071 Common Report Var(flag_split_wide_types) Optimization
1072 Split wide types into independent registers
1074 fvariable-expansion-in-unroller
1075 Common Report Var(flag_variable_expansion_in_unroller) Optimization
1076 Apply variable expansion when loops are unrolled
1079 Common Report RejectNegative Joined
1080 -fstack-check=[no|generic|specific] Insert stack checking code into the program
1084 Insert stack checking code into the program. Same as -fstack-check=specific
1089 fstack-limit-register=
1090 Common RejectNegative Joined
1091 -fstack-limit-register=<register> Trap if the stack goes past <register>
1093 fstack-limit-symbol=
1094 Common RejectNegative Joined
1095 -fstack-limit-symbol=<name> Trap if the stack goes past symbol <name>
1098 Common Report Var(flag_stack_protect, 1)
1099 Use propolice as a stack protection method
1101 fstack-protector-all
1102 Common Report RejectNegative Var(flag_stack_protect, 2) VarExists
1103 Use a stack protection method for every function
1107 Does nothing. Preserved for backward compatibility.
1109 ; Nonzero if we should do (language-dependent) alias analysis.
1110 ; Typically, this analysis will assume that expressions of certain
1111 ; types do not alias expressions of certain other types. Only used
1112 ; if alias analysis (in general) is enabled.
1114 Common Report Var(flag_strict_aliasing) Optimization
1115 Assume strict aliasing rules apply
1118 Common Report Var(flag_strict_overflow)
1119 Treat signed overflow as undefined
1122 Common Report Var(flag_syntax_only)
1123 Check for syntax errors, then stop
1126 Common Report Var(flag_test_coverage)
1127 Create data files needed by \"gcov\"
1130 Common Report Var(flag_thread_jumps) Optimization
1131 Perform jump threading optimizations
1134 Common Report Var(time_report)
1135 Report the time taken by each compiler pass
1138 Common Joined RejectNegative
1139 -ftls-model=[global-dynamic|local-dynamic|initial-exec|local-exec] Set the default thread-local storage code generation model
1142 Common Report Var(flag_toplevel_reorder) Init(2) Optimization
1143 Reorder top level functions, variables, and asms
1146 Common Report Var(flag_tracer)
1147 Perform superblock formation via tail duplication
1149 ; Zero means that floating-point math operations cannot generate a
1150 ; (user-visible) trap. This is the case, for example, in nonstop
1151 ; IEEE 754 arithmetic.
1153 Common Report Var(flag_trapping_math) Init(1) Optimization
1154 Assume floating-point operations can trap
1157 Common Report Var(flag_trapv) Optimization
1158 Trap for signed overflow in addition, subtraction and multiplication
1161 Common Report Var(flag_tree_ccp) Optimization
1162 Enable SSA-CCP optimization on trees
1166 Does nothing. Preserved for backward compatibility.
1169 Common Report Var(flag_tree_ch) Optimization
1170 Enable loop header copying on trees
1173 Common Report Var(flag_tree_copyrename) Optimization
1174 Replace SSA temporaries with better names in copies
1177 Common Report Var(flag_tree_copy_prop) Optimization
1178 Enable copy propagation on trees
1180 ftree-store-copy-prop
1182 Does nothing. Preserved for backward compatibility.
1185 Common Report Var(flag_tree_cselim) Init(2) Optimization
1186 Transform condition stores into unconditional ones
1188 ftree-switch-conversion
1189 Common Report Var(flag_tree_switch_conversion) Optimization
1190 Perform conversions of switch initializations.
1193 Common Report Var(flag_tree_dce) Optimization
1194 Enable SSA dead code elimination optimization on trees
1196 ftree-dominator-opts
1197 Common Report Var(flag_tree_dom) Optimization
1198 Enable dominator optimizations
1201 Common Report Var(flag_tree_dse) Optimization
1202 Enable dead store elimination
1205 Common Report Var(flag_tree_fre) Optimization
1206 Enable Full Redundancy Elimination (FRE) on trees
1208 ftree-loop-distribution
1209 Common Report Var(flag_tree_loop_distribution) Optimization
1210 Enable loop distribution on trees
1213 Common Report Var(flag_tree_loop_im) Init(1) Optimization
1214 Enable loop invariant motion on trees
1217 Common Report Var(flag_tree_loop_linear) Optimization
1218 Enable linear loop transforms on trees
1221 Common Report Var(flag_tree_loop_ivcanon) Init(1) Optimization
1222 Create canonical induction variables in loops
1225 Common Report Var(flag_tree_loop_optimize) Init(1) Optimization
1226 Enable loop optimizations on tree level
1228 ftree-parallelize-loops=
1229 Common Report Joined UInteger Var(flag_tree_parallelize_loops) Init(1)
1230 Enable automatic parallelization of loops
1233 Common Report Var(flag_tree_pre) Optimization
1234 Enable SSA-PRE optimization on trees
1237 Common Report Var(flag_tree_reassoc) Init(1) Optimization
1238 Enable reassociation on tree level
1242 Does nothing. Preserved for backward compatibility.
1245 Common Report Var(flag_tree_sink) Optimization
1246 Enable SSA code sinking on trees
1249 Common Report Var(flag_tree_sra) Optimization
1250 Perform scalar replacement of aggregates
1253 Common Report Var(flag_tree_ter) Init(1) Optimization
1254 Replace temporary expressions in the SSA->normal pass
1257 Common Report Var(flag_tree_live_range_split) Optimization
1258 Perform live range splitting during the SSA->normal pass
1261 Common Report Var(flag_tree_vrp) Init(0) Optimization
1262 Perform Value Range Propagation on trees
1265 Common Report Var(flag_unit_at_a_time) Init(1) Optimization
1266 Compile whole compilation unit at a time
1269 Common Report Var(flag_unroll_loops) Optimization
1270 Perform loop unrolling when iteration count is known
1273 Common Report Var(flag_unroll_all_loops) Optimization
1274 Perform loop unrolling for all loops
1276 ; Nonzero means that loop optimizer may assume that the induction variables
1277 ; that control loops do not overflow and that the loops with nontrivial
1278 ; exit condition are not infinite
1279 funsafe-loop-optimizations
1280 Common Report Var(flag_unsafe_loop_optimizations) Optimization
1281 Allow loop optimizations to assume that the loops behave in normal way
1284 Common Report Var(flag_associative_math)
1285 Allow optimization for floating-point arithmetic which may change the
1286 result of the operation due to rounding.
1289 Common Report Var(flag_reciprocal_math)
1290 Same as -fassociative-math for expressions which include division.
1292 ; Nonzero means that unsafe floating-point math optimizations are allowed
1293 ; for the sake of speed. IEEE compliance is not guaranteed, and operations
1294 ; are allowed to assume that their arguments and results are "normal"
1295 ; (e.g., nonnegative for SQRT).
1296 funsafe-math-optimizations
1297 Common Report Var(flag_unsafe_math_optimizations) Optimization
1298 Allow math optimizations that may violate IEEE or ISO standards
1301 Common Report Var(flag_unswitch_loops) Optimization
1302 Perform loop unswitching
1305 Common Report Var(flag_unwind_tables) Optimization
1306 Just generate unwind tables for exception handling
1309 Common Report Var(flag_var_tracking) VarExists Optimization
1310 Perform variable tracking
1312 fvar-tracking-uninit
1313 Common Report Var(flag_var_tracking_uninit) Optimization
1314 Perform variable tracking and also tag variables that are uninitialized
1317 Common Report Var(flag_tree_vectorize) Optimization
1318 Enable loop vectorization on trees
1321 Common Report Var(flag_vect_cost_model) Optimization
1322 Enable use of cost model in vectorization
1324 ftree-vect-loop-version
1325 Common Report Var(flag_tree_vect_loop_version) Init(1) Optimization
1326 Enable loop versioning when doing loop vectorization on trees
1328 ftree-vectorizer-verbose=
1329 Common RejectNegative Joined
1330 -ftree-vectorizer-verbose=<number> Set the verbosity level of the vectorizer
1333 Common Report Var(flag_tree_scev_cprop) Init(1) Optimization
1334 Enable copy propagation of scalar-evolution information.
1336 ; -fverbose-asm causes extra commentary information to be produced in
1337 ; the generated assembly code (to make it more readable). This option
1338 ; is generally only of use to those who actually need to read the
1339 ; generated assembly code (perhaps while debugging the compiler itself).
1340 ; -fno-verbose-asm, the default, causes the extra information
1341 ; to not be added and is useful when comparing two assembler files.
1343 Common Report Var(flag_verbose_asm)
1344 Add extra commentary to assembler output
1347 Common Joined RejectNegative
1348 -fvisibility=[default|internal|hidden|protected] Set the default symbol visibility
1352 Common Report Var(flag_value_profile_transformations) Optimization
1353 Use expression value profiles in optimizations
1356 Common Report Var(flag_web) Init(2) Optimization
1357 Construct webs and split unrelated uses of single variable
1359 ftree-builtin-call-dce
1360 Common Report Var(flag_tree_builtin_call_dce) Init(0) Optimization
1361 Enable conditional dead code elimination for builtin calls
1364 Common Report Var(flag_whole_program) Init(0) Optimization
1365 Perform whole program optimizations
1368 Common Report Var(flag_wrapv) Optimization
1369 Assume signed arithmetic overflow wraps around
1371 fzero-initialized-in-bss
1372 Common Report Var(flag_zero_initialized_in_bss) Init(1)
1373 Put zero initialized data in the bss section
1376 Common JoinedOrMissing
1377 Generate debug information in default format
1380 Common JoinedOrMissing Negative(gdwarf-2)
1381 Generate debug information in COFF format
1384 Common JoinedOrMissing Negative(gstabs)
1385 Generate debug information in DWARF v2 format
1388 Common JoinedOrMissing
1389 Generate debug information in default extended format
1392 Common JoinedOrMissing Negative(gstabs+)
1393 Generate debug information in STABS format
1396 Common JoinedOrMissing Negative(gvms)
1397 Generate debug information in extended STABS format
1400 Common JoinedOrMissing Negative(gxcoff)
1401 Generate debug information in VMS format
1404 Common JoinedOrMissing Negative(gxcoff+)
1405 Generate debug information in XCOFF format
1408 Common JoinedOrMissing Negative(gcoff)
1409 Generate debug information in extended XCOFF format
1412 Common Joined Separate
1413 -o <file> Place output into <file>
1416 Common Var(profile_flag)
1417 Enable function profiling
1420 Common Var(pedantic)
1421 Issue warnings needed for strict compliance to the standard
1425 Like -pedantic but issue them as errors
1428 Common Var(quiet_flag)
1429 Do not display functions compiled or elapsed time
1432 Common Var(version_flag)
1433 Display the compiler's version
1436 Common Var(inhibit_warnings)
1440 Common RejectNegative Negative(pie)
1441 Create a shared library
1444 Common RejectNegative Negative(shared)
1445 Create a position independent executable
1447 ; This comment is to ensure we retain the blank line above.