1 ; Options for the language- and target-independent parts of the compiler.
3 ; Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009
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
98 Common Var(warnings_are_errors)
99 Treat all warnings as errors
103 Treat specified warning as error
107 Print extra (possibly unwanted) warnings
110 Common Var(flag_fatal_errors)
111 Exit on the first error occurred
114 Common RejectNegative Joined UInteger
115 -Wframe-larger-than=<number> Warn if a function's stack frame requires more than <number> bytes
118 Common Var(warn_inline) Warning
119 Warn when an inlined function cannot be inlined
122 Common RejectNegative Joined UInteger Warning
125 Common RejectNegative Joined UInteger Warning
126 -Wlarger-than=<number> Warn if an object is larger than <number> bytes
129 Common Warning Var(warn_logical_op)
130 Warn when a logical operator is suspicously always evaluating to true or false
132 Wunsafe-loop-optimizations
133 Common Var(warn_unsafe_loop_optimizations) Warning
134 Warn if the loop cannot be optimized due to nontrivial assumptions.
137 Common Var(warn_missing_noreturn) Warning
138 Warn about functions which might be candidates for __attribute__((noreturn))
141 Common Var(warn_mudflap) Init(1) Warning
142 Warn about constructs not instrumented by -fmudflap
145 Common Var(warn_overflow) Init(1) Warning
146 Warn about overflow in arithmetic expressions
149 Common Var(warn_packed) Warning
150 Warn when the packed attribute has no effect on struct layout
153 Common Var(warn_padded) Warning
154 Warn when padding is required to align structure members
157 Common Var(warn_shadow) Warning
158 Warn when one local variable shadows another
161 Common Var(warn_stack_protect) Warning
162 Warn when not issuing stack smashing protection for some reason
166 Warn about code which might break strict aliasing rules
169 Common Joined UInteger Var(warn_strict_aliasing) Init(-1) Warning
170 Warn about code which might break strict aliasing rules
174 Warn about optimizations that assume that signed overflow is undefined
177 Common Joined UInteger Var(warn_strict_overflow) Init(-1) Warning
178 Warn about optimizations that assume that signed overflow is undefined
181 Common Var(warn_switch) Warning
182 Warn about enumerated switches, with no default, missing a case
185 Common Var(warn_switch_default) Warning
186 Warn about enumerated switches missing a \"default:\" statement
189 Common Var(warn_switch_enum) Warning
190 Warn about all enumerated switches missing a specific case
193 Common Var(warn_system_headers) Warning
194 Do not suppress warnings from system headers
197 Common Var(warn_type_limits) Init(-1) Warning
198 Warn if a comparison is always true or always false due to the limited range of the data type
201 Common Var(warn_uninitialized) Warning
202 Warn about uninitialized automatic variables
205 Common Var(warn_notreached) Warning
206 Warn about code that will never be executed
209 Common Var(warn_unused) Init(0) Warning
210 Enable all -Wunused- warnings
213 Common Var(warn_unused_function) Init(-1) Warning
214 Warn when a function is unused
217 Common Var(warn_unused_label) Init(-1) Warning
218 Warn when a label is unused
221 Common Var(warn_unused_parameter) Init(-1) Warning
222 Warn when a function parameter is unused
225 Common Var(warn_unused_value) Init(-1) Warning
226 Warn when an expression value is unused
229 Common Var(warn_unused_variable) Init(-1) Warning
230 Warn when a variable is unused
233 Common RejectNegative Var(warn_coverage_mismatch) Warning
234 Warn instead of error in case profiles in -fprofile-use do not match
238 -aux-info <file> Emit declaration information into <file>
251 -d<letters> Enable dumps from specific passes of the compiler
255 -dumpbase <file> Set the file basename to be used for dumps
257 ; The version of the C++ ABI in use. The following values are allowed:
259 ; 0: The version of the ABI believed most conformant with the C++ ABI
260 ; specification. This ABI may change as bugs are discovered and fixed.
261 ; Therefore, 0 will not necessarily indicate the same ABI in different
264 ; 1: The version of the ABI first used in G++ 3.2.
266 ; 2: The version of the ABI first used in G++ 3.4.
268 ; Additional positive integers will be assigned as new versions of
269 ; the ABI become the default version of the ABI.
271 Common Joined UInteger Var(flag_abi_version) Init(2)
274 Common Report Var(align_functions,0) Optimization UInteger
275 Align the start of functions
278 Common RejectNegative Joined UInteger
281 Common Report Var(align_jumps,0) Optimization UInteger
282 Align labels which are only reached by jumping
285 Common RejectNegative Joined UInteger
288 Common Report Var(align_labels,0) Optimization UInteger
292 Common RejectNegative Joined UInteger
295 Common Report Var(align_loops) Optimization UInteger
296 Align the start of loops
299 Common RejectNegative Joined UInteger
301 ; This flag is only tested if alias checking is enabled.
302 ; 0 if pointer arguments may alias each other. True in C.
303 ; 1 if pointer arguments may not alias each other but may alias
305 ; 2 if pointer arguments may not alias each other and may not
306 ; alias global variables.
307 ; 3 if pointer arguments may not alias anything. True in Fortran.
308 ; Set by the front end.
310 Common Report Var(flag_argument_noalias,0) Optimization
311 Specify that arguments may alias each other and globals
314 Common Report Var(flag_argument_noalias,1) VarExists Optimization
315 Assume arguments may alias globals but not each other
317 fargument-noalias-global
318 Common Report Var(flag_argument_noalias,2) VarExists Optimization
319 Assume arguments alias neither each other nor globals
321 fargument-noalias-anything
322 Common Report Var(flag_argument_noalias,3) VarExists Optimization
323 Assume arguments alias no other storage
325 fasynchronous-unwind-tables
326 Common Report Var(flag_asynchronous_unwind_tables) Optimization
327 Generate unwind tables that are exact at each instruction boundary
330 Common Report Var(flag_auto_inc_dec) Init(1)
331 Generate auto-inc/dec instructions
333 ; -fcheck-bounds causes gcc to generate array bounds checks.
334 ; For C, C++ and ObjC: defaults off.
335 ; For Java: defaults to on.
336 ; For Fortran: defaults to off.
338 Common Report Var(flag_bounds_check)
339 Generate code to check bounds before indexing arrays
342 Common Report Var(flag_branch_on_count_reg) Init(1) Optimization
343 Replace add, compare, branch with branch on count register
345 fbranch-probabilities
346 Common Report Var(flag_branch_probabilities) Optimization
347 Use profiling information for branch probabilities
349 fbranch-target-load-optimize
350 Common Report Var(flag_branch_target_load_optimize) Optimization
351 Perform branch target load optimization before prologue / epilogue threading
353 fbranch-target-load-optimize2
354 Common Report Var(flag_branch_target_load_optimize2) Optimization
355 Perform branch target load optimization after prologue / epilogue threading
358 Common Report Var(flag_btr_bb_exclusive) Optimization
359 Restrict target load migration not to re-use registers in any basic block
362 Common Joined RejectNegative
363 -fcall-saved-<register> Mark <register> as being preserved across functions
366 Common Joined RejectNegative
367 -fcall-used-<register> Mark <register> as being corrupted by function calls
369 ; Nonzero for -fcaller-saves: allocate values in regs that need to
370 ; be saved across function calls, if that produces overall better code.
371 ; Optional now, so people can test it.
373 Common Report Var(flag_caller_saves) Optimization
374 Save registers around function calls
377 Common Report Var(flag_check_data_deps)
378 Compare the results of several data dependence analyzers.
381 Common Report Var(flag_no_common,0) Optimization
382 Do not put uninitialized globals in the common section
385 Common Var(flag_conserve_stack) Optimization
386 Do not perform optimizations increasing noticeably stack usage
389 Common Report Var(flag_cprop_registers) Optimization
390 Perform a register copy-propagation optimization pass
393 Common Report Var(flag_crossjumping) Optimization
394 Perform cross-jumping optimization
397 Common Report Var(flag_cse_follow_jumps) Optimization
398 When running CSE, follow jumps to their targets
401 Common Report Var(flag_cse_skip_blocks) Optimization
402 When running CSE, follow conditional jumps
405 Common Report Var(flag_cx_limited_range) Optimization
406 Omit range reduction step when performing complex division
409 Common Report Var(flag_cx_fortran_rules) Optimization
410 Complex multiplication and division follow Fortran rules
413 Common Report Var(flag_data_sections) Optimization
414 Place data items into their own section
418 List all available debugging counters with their limits and counts.
421 Common RejectNegative Joined
422 -fdbg-cnt=<counter>:<limit>[,<counter>:<limit>,...] Set the debug counter limit.
425 Common Joined RejectNegative
426 Map one directory name to another in debug information
428 ; Nonzero for -fdefer-pop: don't pop args after each function call
429 ; instead save them up to pop many calls' args with one insns.
431 Common Report Var(flag_defer_pop) Optimization
432 Defer popping functions args from stack until later
435 Common Report Var(flag_delayed_branch) Optimization
436 Attempt to fill delay slots of branch instructions
438 fdelete-null-pointer-checks
439 Common Report Var(flag_delete_null_pointer_checks) Optimization
440 Delete useless null pointer checks
442 fdiagnostics-show-location=
443 Common Joined RejectNegative
444 -fdiagnostics-show-location=[once|every-line] How often to emit source location at the beginning of line-wrapped diagnostics
446 fdiagnostics-show-option
448 Amend appropriate diagnostic messages with the command line option that controls them
451 Common Joined RejectNegative
452 -fdump-<type> Dump various compiler internals to a file
455 Common Report Var(flag_dump_noaddr)
456 Suppress output of addresses in debugging dumps
459 Common Report Var(flag_dump_unnumbered) VarExists
460 Suppress output of instruction numbers, line number notes and addresses in debugging dumps
463 Common Report Var(flag_dwarf2_cfi_asm) Init(HAVE_GAS_CFI_DIRECTIVE)
464 Enable CFI tables via GAS assembler directives.
467 Common Report Var(flag_early_inlining) Init(1) Optimization
468 Perform early inlining
470 feliminate-dwarf2-dups
471 Common Report Var(flag_eliminate_dwarf2_dups)
472 Perform DWARF2 duplicate elimination
474 feliminate-unused-debug-symbols
475 Common Report Var(flag_debug_only_used_symbols)
476 Perform unused type elimination in debug info
478 feliminate-unused-debug-types
479 Common Report Var(flag_eliminate_unused_debug_types) Init(1)
480 Perform unused type elimination in debug info
482 femit-class-debug-always
483 Common Report Var(flag_emit_class_debug_always) Init(0)
484 Do not suppress C++ class debug information.
487 Common Report Var(flag_exceptions) Optimization
488 Enable exception handling
490 fexpensive-optimizations
491 Common Report Var(flag_expensive_optimizations) Optimization
492 Perform a number of minor, expensive optimizations
498 Common Report Var(flag_finite_math_only) Optimization
499 Assume no NaNs or infinities are generated
502 Common Joined RejectNegative
503 -ffixed-<register> Mark <register> as being unavailable to the compiler
506 Common Report Var(flag_float_store) Optimization
507 Don't allocate floats and doubles in extended-precision registers
511 Does nothing. Preserved for backward compatibility.
514 Common Report Var(flag_forward_propagate) Optimization
515 Perform a forward propagation pass on RTL
517 ; Nonzero means don't put addresses of constant functions in registers.
518 ; Used for compiling the Unix kernel, where strange substitutions are
519 ; done on the assembly output.
521 Common Report Var(flag_no_function_cse,0)
522 Allow function addresses to be held in registers
525 Common Report Var(flag_function_sections)
526 Place each function into its own section
529 Common Report Var(flag_gcse) Optimization
530 Perform global common subexpression elimination
533 Common Report Var(flag_gcse_lm) Init(1) Optimization
534 Perform enhanced load motion during global common subexpression elimination
537 Common Report Var(flag_gcse_sm) Init(0) Optimization
538 Perform store motion after global common subexpression elimination
541 Common Report Var(flag_gcse_las) Init(0) Optimization
542 Perform redundant load after store elimination in global common subexpression
546 Common Report Var(flag_gcse_after_reload) Optimization
547 Perform global common subexpression elimination after register allocation
550 ; This option is not documented yet as its semantics will change.
552 Common Report Var(flag_graphite)
553 Enable in and out of Graphite representation
556 Common Report Var(flag_loop_strip_mine) Optimization
557 Enable Loop Strip Mining transformation
560 Common Report Var(flag_loop_interchange) Optimization
561 Enable Loop Interchange transformation
564 Common Report Var(flag_loop_block) Optimization
565 Enable Loop Blocking transformation
567 ; This option is not documented as it does not perform any useful optimization.
569 Common Report Var(flag_graphite_identity) Optimization
570 Enable Graphite Identity transformation
572 fguess-branch-probability
573 Common Report Var(flag_guess_branch_prob) Optimization
574 Enable guessing of branch probabilities
576 ; Nonzero means ignore `#ident' directives. 0 means handle them.
577 ; Generate position-independent code for executables if possible
578 ; On SVR4 targets, it also controls whether or not to emit a
579 ; string identifying the compiler.
581 Common Report Var(flag_no_ident,0)
582 Process #ident directives
585 Common Report Var(flag_if_conversion) Optimization
586 Perform conversion of conditional jumps to branchless equivalents
589 Common Report Var(flag_if_conversion2) Optimization
590 Perform conversion of conditional jumps to conditional execution
592 ; -finhibit-size-directive inhibits output of .size for ELF.
593 ; This is used only for compiling crtstuff.c,
594 ; and it may be extended to other effects
595 ; needed for crtstuff.c on other systems.
596 finhibit-size-directive
597 Common Report Var(flag_inhibit_size_directive)
598 Do not generate .size directives
601 Common Report Var(flag_indirect_inlining)
602 Perform indirect inlining
604 ; Nonzero means that functions declared `inline' will be treated
605 ; as `static'. Prevents generation of zillions of copies of unused
606 ; static inline functions; instead, `inlines' are written out
607 ; only when actually used. Used in conjunction with -g. Also
608 ; does the right thing with #pragma interface.
610 Common Report Var(flag_no_inline,0) Init(0)
611 Pay attention to the \"inline\" keyword
613 finline-small-functions
614 Common Report Var(flag_inline_small_functions) Optimization
615 Integrate simple functions into their callers when code size is known to not growth
618 Common Report Var(flag_inline_functions) Optimization
619 Integrate simple functions into their callers
621 finline-functions-called-once
622 Common Report Var(flag_inline_functions_called_once) Init(1) Optimization
623 Integrate functions called once into their callers
626 Common RejectNegative Joined UInteger
629 Common RejectNegative Joined UInteger
630 -finline-limit=<number> Limit the size of inlined functions to <number>
632 finstrument-functions
633 Common Report Var(flag_instrument_function_entry_exit)
634 Instrument function entry and exit with profiling calls
636 finstrument-functions-exclude-function-list=
637 Common RejectNegative Joined
638 -finstrument-functions-exclude-function-list=name,... Do not instrument listed functions
640 finstrument-functions-exclude-file-list=
641 Common RejectNegative Joined
642 -finstrument-functions-exclude-file-list=filename,... Do not instrument functions listed in files
645 Common Report Var(flag_ipa_cp) Optimization
646 Perform Interprocedural constant propagation
649 Common Report Var(flag_ipa_cp_clone) Optimization
650 Perform cloning to make Interprocedural constant propagation stronger
653 Common Report Var(flag_ipa_pure_const) Init(0) Optimization
654 Discover pure and const functions
657 Common Report Var(flag_ipa_pta) Init(0) Optimization
658 Perform interprocedural points-to analysis
661 Common Report Var(flag_ipa_reference) Init(0) Optimization
662 Discover readonly and non addressable static variables
665 Common Report Var(flag_ipa_type_escape) Init(0) Optimization
666 Type based escape and alias analysis
669 Common Report Var(flag_ipa_matrix_reorg) Optimization
670 Perform matrix layout flattening and transposing based
671 on profiling information.
674 Common Report Var(flag_ipa_struct_reorg)
675 Perform structure layout optimizations based
676 on profiling information.
679 Common Joined RejectNegative
680 -fira-algorithm=[CB|priority] Set the used IRA algorithm
683 Common Joined RejectNegative
684 -fira-region=[one|all|mixed] Set regions for IRA
687 Common Report Var(flag_ira_coalesce) Init(0)
688 Do optimistic coalescing.
690 fira-share-save-slots
691 Common Report Var(flag_ira_share_save_slots) Init(1)
692 Share slots for saving different hard registers.
694 fira-share-spill-slots
695 Common Report Var(flag_ira_share_spill_slots) Init(1)
696 Share stack slots for spilled pseudo-registers.
699 Common RejectNegative Joined UInteger
700 -fira-verbose=<number> Control IRA's level of diagnostic messages.
703 Common Report Var(flag_ivopts) Init(1) Optimization
704 Optimize induction variables on trees
707 Common Var(flag_jump_tables) Init(1) Optimization
708 Use jump tables for sufficiently large switch statements
710 fkeep-inline-functions
711 Common Report Var(flag_keep_inline_functions)
712 Generate code for functions even if they are fully inlined
715 Common Report Var(flag_keep_static_consts) Init(1)
716 Emit static const variables even if they are not used
719 Common Report Var(flag_leading_underscore) Init(-1)
720 Give external symbols a leading underscore
724 Does nothing. Preserved for backward compatibility.
727 Common Report Var(flag_errno_math) Init(1) Optimization
728 Set errno after built-in math functions
731 Common Report Var(mem_report)
732 Report on permanent memory allocation
734 ; This will attempt to merge constant section constants, if 1 only
735 ; string constants and constants from constant pool, if 2 also constant
738 Common Report Var(flag_merge_constants,2) Init(1) Optimization
739 Attempt to merge identical constants and constant variables
742 Common Report Var(flag_merge_constants,1) VarExists Optimization
743 Attempt to merge identical constants across compilation units
746 Common Report Var(flag_merge_debug_strings) Init(1)
747 Attempt to merge identical debug strings across compilation units
750 Common RejectNegative Joined UInteger
751 -fmessage-length=<number> Limit diagnostics to <number> characters per line. 0 suppresses line-wrapping
754 Common Report Var(flag_modulo_sched) Optimization
755 Perform SMS based modulo scheduling before the first scheduling pass
757 fmodulo-sched-allow-regmoves
758 Common Report Var(flag_modulo_sched_allow_regmoves)
759 Perform SMS based modulo scheduling with register moves allowed
761 fmove-loop-invariants
762 Common Report Var(flag_move_loop_invariants) Init(1) Optimization
763 Move loop invariant computations out of loops
766 Common RejectNegative Report Var(flag_mudflap)
767 Add mudflap bounds-checking instrumentation for single-threaded program
770 Common RejectNegative Report VarExists Var(flag_mudflap,2)
771 Add mudflap bounds-checking instrumentation for multi-threaded program
774 Common RejectNegative Report Var(flag_mudflap_ignore_reads)
775 Ignore read operations when inserting mudflap instrumentation
778 Common Var(flag_dce) Init(1) Optimization
779 Use the RTL dead code elimination pass
782 Common Var(flag_dse) Init(1) Optimization
783 Use the RTL dead store elimination pass
785 freschedule-modulo-scheduled-loops
786 Common Report Var(flag_resched_modulo_sched) Optimization
787 Enable/Disable the traditional scheduling in loops that already passed modulo scheduling
790 Common Report Var(flag_non_call_exceptions) Optimization
791 Support synchronous non-call exceptions
794 Common Report Var(flag_omit_frame_pointer) Optimization
795 When possible do not generate stack frames
797 foptimize-register-move
798 Common Report Var(flag_regmove) Optimization
799 Do the full register move optimization pass
801 foptimize-sibling-calls
802 Common Report Var(flag_optimize_sibling_calls) Optimization
803 Optimize sibling and tail recursive calls
806 Common Report Var(pre_ipa_mem_report)
807 Report on memory allocation before interprocedural optimization
810 Common Report Var(post_ipa_mem_report)
811 Report on memory allocation before interprocedural optimization
814 Common Report Var(flag_pack_struct) Optimization
815 Pack structure members together without holes
818 Common RejectNegative Joined UInteger Optimization
819 -fpack-struct=<number> Set initial maximum structure member alignment
822 Common Report Var(flag_pcc_struct_return,1) VarExists
823 Return small aggregates in memory, not registers
826 Common Report Var(flag_peel_loops) Optimization
830 Common Report Var(flag_no_peephole,0) Optimization
831 Enable machine specific peephole optimizations
834 Common Report Var(flag_peephole2) Optimization
835 Enable an RTL peephole pass before sched2
838 Common Report Var(flag_pic,2)
839 Generate position-independent code if possible (large mode)
842 Common Report Var(flag_pie,2)
843 Generate position-independent code for executables if possible (large mode)
846 Common Report Var(flag_pic,1) VarExists
847 Generate position-independent code if possible (small mode)
850 Common Report Var(flag_pie,1) VarExists
851 Generate position-independent code for executables if possible (small mode)
853 fpredictive-commoning
854 Common Report Var(flag_predictive_commoning) Optimization
855 Run predictive commoning optimization.
857 fprefetch-loop-arrays
858 Common Report Var(flag_prefetch_loop_arrays) Optimization
859 Generate prefetch instructions, if available, for arrays in loops
862 Common Report Var(profile_flag)
863 Enable basic program profiling code
866 Common Report Var(profile_arc_flag)
867 Insert arc-based program profiling code
870 Common Joined RejectNegative
871 Set the top-level directory for storing the profile data.
872 The default is 'pwd'.
875 Common Report Var(flag_profile_correction)
876 Enable correction of flow inconsistent profile data input
880 Enable common options for generating profile info for profile feedback directed optimizations
883 Common Joined RejectNegative
884 Enable common options for generating profile info for profile feedback directed optimizations, and set -fprofile-dir=
887 Common Var(flag_profile_use)
888 Enable common options for performing profile feedback directed optimizations
891 Common Joined RejectNegative
892 Enable common options for performing profile feedback directed optimizations, and set -fprofile-dir=
895 Common Report Var(flag_profile_values)
896 Insert code to profile values of expressions
902 Common Joined RejectNegative
903 -frandom-seed=<string> Make compile reproducible using <string>
905 ; This switch causes the command line that was used to create an
906 ; object file to be recorded into the object file. The exact format
907 ; of this recording is target and binary file format dependent.
908 ; It is related to the -fverbose-asm switch, but that switch only
909 ; records information in the assembler output file as comments, so
910 ; they never reach the object file.
912 Common Report Var(flag_record_gcc_switches)
913 Record gcc command line switches in the object file.
916 Common Report Var(flag_pcc_struct_return,0) VarExists Optimization
917 Return small aggregates in registers
920 Common Report Var(flag_regmove) Optimization
921 Enables a register move optimization
924 Common Report Var(flag_rename_registers) Init(2) Optimization
925 Perform a register renaming optimization pass
928 Common Report Var(flag_reorder_blocks) Optimization
929 Reorder basic blocks to improve code placement
931 freorder-blocks-and-partition
932 Common Report Var(flag_reorder_blocks_and_partition) Optimization
933 Reorder basic blocks and partition into hot and cold sections
936 Common Report Var(flag_reorder_functions) Optimization
937 Reorder functions to improve code placement
939 frerun-cse-after-loop
940 Common Report Var(flag_rerun_cse_after_loop) Init(2) Optimization
941 Add a common subexpression elimination pass after loop optimizations
945 Does nothing. Preserved for backward compatibility.
948 Common Report Var(flag_rounding_math) Optimization
949 Disable optimizations that assume default FP rounding behavior
952 Common Report Var(flag_schedule_interblock) Init(1) Optimization
953 Enable scheduling across basic blocks
956 Common Report Var(flag_schedule_speculative) Init(1) Optimization
957 Allow speculative motion of non-loads
960 Common Report Var(flag_schedule_speculative_load) Optimization
961 Allow speculative motion of some loads
963 fsched-spec-load-dangerous
964 Common Report Var(flag_schedule_speculative_load_dangerous) Optimization
965 Allow speculative motion of more loads
968 Common RejectNegative Joined
969 -fsched-verbose=<number> Set the verbosity level of the scheduler
971 fsched2-use-superblocks
972 Common Report Var(flag_sched2_use_superblocks) Optimization
973 If scheduling post reload, do superblock scheduling
976 Common Report Var(flag_sched2_use_traces) Optimization
977 If scheduling post reload, do trace scheduling
980 Common Report Var(flag_schedule_insns) Optimization
981 Reschedule instructions before register allocation
984 Common Report Var(flag_schedule_insns_after_reload) Optimization
985 Reschedule instructions after register allocation
987 ; This flag should be on when a target implements non-trivial
988 ; scheduling hooks, maybe saving some information for its own sake.
989 ; On IA64, for example, this is used for correct bundling.
990 fselective-scheduling
991 Common Report Var(flag_selective_scheduling) Optimization
992 Schedule instructions using selective scheduling algorithm
994 fselective-scheduling2
995 Common Report Var(flag_selective_scheduling2) Optimization
996 Run selective scheduling after reload
998 fsel-sched-pipelining
999 Common Report Var(flag_sel_sched_pipelining) Init(0) Optimization
1000 Perform software pipelining of inner loops during selective scheduling
1002 fsel-sched-pipelining-outer-loops
1003 Common Report Var(flag_sel_sched_pipelining_outer_loops) Init(0) Optimization
1004 Perform software pipelining of outer loops during selective scheduling
1006 fsel-sched-reschedule-pipelined
1007 Common Report Var(flag_sel_sched_reschedule_pipelined) Init(0) Optimization
1008 Reschedule pipelined regions without pipelining
1010 ; sched_stalled_insns means that insns can be moved prematurely from the queue
1011 ; of stalled insns into the ready list.
1012 fsched-stalled-insns
1013 Common Report Var(flag_sched_stalled_insns) Optimization UInteger
1014 Allow premature scheduling of queued insns
1016 fsched-stalled-insns=
1017 Common RejectNegative Joined UInteger
1018 -fsched-stalled-insns=<number> Set number of queued insns that can be prematurely scheduled
1020 ; sched_stalled_insns_dep controls how many recently scheduled cycles will
1021 ; be examined for a dependency on a stalled insn that is candidate for
1022 ; premature removal from the queue of stalled insns into the ready list (has
1023 ; an effect only if the flag 'sched_stalled_insns' is set).
1024 fsched-stalled-insns-dep
1025 Common Report Var(flag_sched_stalled_insns_dep,1) Init(1) Optimization UInteger
1026 Set dependence distance checking in premature scheduling of queued insns
1028 fsched-stalled-insns-dep=
1029 Common RejectNegative Joined UInteger
1030 -fsched-stalled-insns-dep=<number> Set dependence distance checking in premature scheduling of queued insns
1033 Common Report Var(flag_section_anchors) Optimization
1034 Access data in the same section from shared anchor points
1036 frtl-abstract-sequences
1037 Common Report Var(flag_rtl_seqabstr) Optimization
1038 Perform sequence abstraction optimization on RTL
1041 Common Report Var(flag_see) Init(0)
1042 Eliminate redundant sign extensions using LCM.
1045 Common C ObjC C++ ObjC++ Report Var(flag_show_column) Init(0)
1046 Show column numbers in diagnostics, when available. Default off
1049 Common Report Var(flag_signaling_nans) Optimization
1050 Disable optimizations observable by IEEE signaling NaNs
1053 Common Report Var(flag_signed_zeros) Init(1) Optimization
1054 Disable floating point optimizations that ignore the IEEE signedness of zero
1056 fsingle-precision-constant
1057 Common Report Var(flag_single_precision_constant) Optimization
1058 Convert floating point constants to single precision constants
1060 fsplit-ivs-in-unroller
1061 Common Report Var(flag_split_ivs_in_unroller) Init(1) Optimization
1062 Split lifetimes of induction variables when loops are unrolled
1065 Common Report Var(flag_split_wide_types) Optimization
1066 Split wide types into independent registers
1068 fvariable-expansion-in-unroller
1069 Common Report Var(flag_variable_expansion_in_unroller) Optimization
1070 Apply variable expansion when loops are unrolled
1073 Common Report RejectNegative Joined
1074 -fstack-check=[no|generic|specific] Insert stack checking code into the program
1078 Insert stack checking code into the program. Same as -fstack-check=specific
1083 fstack-limit-register=
1084 Common RejectNegative Joined
1085 -fstack-limit-register=<register> Trap if the stack goes past <register>
1087 fstack-limit-symbol=
1088 Common RejectNegative Joined
1089 -fstack-limit-symbol=<name> Trap if the stack goes past symbol <name>
1092 Common Report Var(flag_stack_protect, 1)
1093 Use propolice as a stack protection method
1095 fstack-protector-all
1096 Common Report RejectNegative Var(flag_stack_protect, 2) VarExists
1097 Use a stack protection method for every function
1101 Does nothing. Preserved for backward compatibility.
1103 ; Nonzero if we should do (language-dependent) alias analysis.
1104 ; Typically, this analysis will assume that expressions of certain
1105 ; types do not alias expressions of certain other types. Only used
1106 ; if alias analysis (in general) is enabled.
1108 Common Report Var(flag_strict_aliasing) Optimization
1109 Assume strict aliasing rules apply
1112 Common Report Var(flag_strict_overflow)
1113 Treat signed overflow as undefined
1116 Common Report Var(flag_syntax_only)
1117 Check for syntax errors, then stop
1120 Common Report Var(flag_test_coverage)
1121 Create data files needed by \"gcov\"
1124 Common Report Var(flag_thread_jumps) Optimization
1125 Perform jump threading optimizations
1128 Common Report Var(time_report)
1129 Report the time taken by each compiler pass
1132 Common Joined RejectNegative
1133 -ftls-model=[global-dynamic|local-dynamic|initial-exec|local-exec] Set the default thread-local storage code generation model
1136 Common Report Var(flag_toplevel_reorder) Init(2) Optimization
1137 Reorder top level functions, variables, and asms
1140 Common Report Var(flag_tracer)
1141 Perform superblock formation via tail duplication
1143 ; Zero means that floating-point math operations cannot generate a
1144 ; (user-visible) trap. This is the case, for example, in nonstop
1145 ; IEEE 754 arithmetic.
1147 Common Report Var(flag_trapping_math) Init(1) Optimization
1148 Assume floating-point operations can trap
1151 Common Report Var(flag_trapv) Optimization
1152 Trap for signed overflow in addition, subtraction and multiplication
1155 Common Report Var(flag_tree_ccp) Optimization
1156 Enable SSA-CCP optimization on trees
1160 Does nothing. Preserved for backward compatibility.
1163 Common Report Var(flag_tree_ch) Optimization
1164 Enable loop header copying on trees
1167 Common Report Var(flag_tree_copyrename) Optimization
1168 Replace SSA temporaries with better names in copies
1171 Common Report Var(flag_tree_copy_prop) Optimization
1172 Enable copy propagation on trees
1174 ftree-store-copy-prop
1176 Does nothing. Preserved for backward compatibility.
1179 Common Report Var(flag_tree_cselim) Init(2) Optimization
1180 Transform condition stores into unconditional ones
1182 ftree-switch-conversion
1183 Common Report Var(flag_tree_switch_conversion) Optimization
1184 Perform conversions of switch initializations.
1187 Common Report Var(flag_tree_dce) Optimization
1188 Enable SSA dead code elimination optimization on trees
1190 ftree-dominator-opts
1191 Common Report Var(flag_tree_dom) Optimization
1192 Enable dominator optimizations
1195 Common Report Var(flag_tree_dse) Optimization
1196 Enable dead store elimination
1199 Common Report Var(flag_tree_fre) Optimization
1200 Enable Full Redundancy Elimination (FRE) on trees
1202 ftree-loop-distribution
1203 Common Report Var(flag_tree_loop_distribution) Optimization
1204 Enable loop distribution on trees
1207 Common Report Var(flag_tree_loop_im) Init(1) Optimization
1208 Enable loop invariant motion on trees
1211 Common Report Var(flag_tree_loop_linear) Optimization
1212 Enable linear loop transforms on trees
1215 Common Report Var(flag_tree_loop_ivcanon) Init(1) Optimization
1216 Create canonical induction variables in loops
1219 Common Report Var(flag_tree_loop_optimize) Init(1) Optimization
1220 Enable loop optimizations on tree level
1222 ftree-parallelize-loops=
1223 Common Report Joined UInteger Var(flag_tree_parallelize_loops) Init(1)
1224 Enable automatic parallelization of loops
1227 Common Report Var(flag_tree_pre) Optimization
1228 Enable SSA-PRE optimization on trees
1231 Common Report Var(flag_tree_reassoc) Init(1) Optimization
1232 Enable reassociation on tree level
1236 Does nothing. Preserved for backward compatibility.
1239 Common Report Var(flag_tree_sink) Optimization
1240 Enable SSA code sinking on trees
1243 Common Report Var(flag_tree_sra) Optimization
1244 Perform scalar replacement of aggregates
1247 Common Report Var(flag_tree_ter) Init(1) Optimization
1248 Replace temporary expressions in the SSA->normal pass
1251 Common Report Var(flag_tree_live_range_split) Optimization
1252 Perform live range splitting during the SSA->normal pass
1255 Common Report Var(flag_tree_vrp) Init(0) Optimization
1256 Perform Value Range Propagation on trees
1259 Common Report Var(flag_unit_at_a_time) Init(1) Optimization
1260 Compile whole compilation unit at a time
1263 Common Report Var(flag_unroll_loops) Optimization
1264 Perform loop unrolling when iteration count is known
1267 Common Report Var(flag_unroll_all_loops) Optimization
1268 Perform loop unrolling for all loops
1270 ; Nonzero means that loop optimizer may assume that the induction variables
1271 ; that control loops do not overflow and that the loops with nontrivial
1272 ; exit condition are not infinite
1273 funsafe-loop-optimizations
1274 Common Report Var(flag_unsafe_loop_optimizations) Optimization
1275 Allow loop optimizations to assume that the loops behave in normal way
1278 Common Report Var(flag_associative_math)
1279 Allow optimization for floating-point arithmetic which may change the
1280 result of the operation due to rounding.
1283 Common Report Var(flag_reciprocal_math)
1284 Same as -fassociative-math for expressions which include division.
1286 ; Nonzero means that unsafe floating-point math optimizations are allowed
1287 ; for the sake of speed. IEEE compliance is not guaranteed, and operations
1288 ; are allowed to assume that their arguments and results are "normal"
1289 ; (e.g., nonnegative for SQRT).
1290 funsafe-math-optimizations
1291 Common Report Var(flag_unsafe_math_optimizations) Optimization
1292 Allow math optimizations that may violate IEEE or ISO standards
1295 Common Report Var(flag_unswitch_loops) Optimization
1296 Perform loop unswitching
1299 Common Report Var(flag_unwind_tables) Optimization
1300 Just generate unwind tables for exception handling
1303 Common Report Var(flag_var_tracking) VarExists Optimization
1304 Perform variable tracking
1306 fvar-tracking-uninit
1307 Common Report Var(flag_var_tracking_uninit) Optimization
1308 Perform variable tracking and also tag variables that are uninitialized
1311 Common Report Var(flag_tree_vectorize) Optimization
1312 Enable loop vectorization on trees
1315 Common Report Var(flag_vect_cost_model) Optimization
1316 Enable use of cost model in vectorization
1318 ftree-vect-loop-version
1319 Common Report Var(flag_tree_vect_loop_version) Init(1) Optimization
1320 Enable loop versioning when doing loop vectorization on trees
1322 ftree-vectorizer-verbose=
1323 Common RejectNegative Joined
1324 -ftree-vectorizer-verbose=<number> Set the verbosity level of the vectorizer
1327 Common Report Var(flag_tree_scev_cprop) Init(1) Optimization
1328 Enable copy propagation of scalar-evolution information.
1330 ; -fverbose-asm causes extra commentary information to be produced in
1331 ; the generated assembly code (to make it more readable). This option
1332 ; is generally only of use to those who actually need to read the
1333 ; generated assembly code (perhaps while debugging the compiler itself).
1334 ; -fno-verbose-asm, the default, causes the extra information
1335 ; to not be added and is useful when comparing two assembler files.
1337 Common Report Var(flag_verbose_asm)
1338 Add extra commentary to assembler output
1341 Common Joined RejectNegative
1342 -fvisibility=[default|internal|hidden|protected] Set the default symbol visibility
1346 Common Report Var(flag_value_profile_transformations) Optimization
1347 Use expression value profiles in optimizations
1350 Common Report Var(flag_web) Init(2) Optimization
1351 Construct webs and split unrelated uses of single variable
1353 ftree-builtin-call-dce
1354 Common Report Var(flag_tree_builtin_call_dce) Init(0) Optimization
1355 Enable conditional dead code elimination for builtin calls
1358 Common Report Var(flag_whole_program) Init(0) Optimization
1359 Perform whole program optimizations
1362 Common Report Var(flag_wrapv) Optimization
1363 Assume signed arithmetic overflow wraps around
1365 fzero-initialized-in-bss
1366 Common Report Var(flag_zero_initialized_in_bss) Init(1)
1367 Put zero initialized data in the bss section
1370 Common JoinedOrMissing
1371 Generate debug information in default format
1374 Common JoinedOrMissing Negative(gdwarf-2)
1375 Generate debug information in COFF format
1378 Common JoinedOrMissing Negative(gstabs)
1379 Generate debug information in DWARF v2 format
1382 Common JoinedOrMissing
1383 Generate debug information in default extended format
1386 Common JoinedOrMissing Negative(gstabs+)
1387 Generate debug information in STABS format
1390 Common JoinedOrMissing Negative(gvms)
1391 Generate debug information in extended STABS format
1394 Common JoinedOrMissing Negative(gxcoff)
1395 Generate debug information in VMS format
1398 Common JoinedOrMissing Negative(gxcoff+)
1399 Generate debug information in XCOFF format
1402 Common JoinedOrMissing Negative(gcoff)
1403 Generate debug information in extended XCOFF format
1406 Common Joined Separate
1407 -o <file> Place output into <file>
1410 Common Var(profile_flag)
1411 Enable function profiling
1414 Common Var(pedantic)
1415 Issue warnings needed for strict compliance to the standard
1419 Like -pedantic but issue them as errors
1422 Common Var(quiet_flag)
1423 Do not display functions compiled or elapsed time
1426 Common Var(version_flag)
1427 Display the compiler's version
1430 Common Var(inhibit_warnings)
1434 Common RejectNegative Negative(pie)
1435 Create a shared library
1438 Common RejectNegative Negative(shared)
1439 Create a position independent executable
1441 ; This comment is to ensure we retain the blank line above.