1 /* params.def - Run-time parameters.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
3 Free Software Foundation, Inc.
4 Written by Mark Mitchell <mark@codesourcery.com>.
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 /* This file contains definitions for language-independent
23 parameters. The DEFPARAM macro takes 6 arguments:
25 - The enumeral corresponding to this parameter.
27 - The name that can be used to set this parameter using the
28 command-line option `--param <name>=<value>'.
30 - A help string explaining how the parameter is used.
32 - A default value for the parameter.
34 - The minimum acceptable value for the parameter.
36 - The maximum acceptable value for the parameter (if greater than
39 Be sure to add an entry to invoke.texi summarizing the parameter. */
41 /* The maximum structure size at which the scalar replacement of
42 aggregates (SRA) pass will perform block copies. The default
43 value, 0, implies that GCC will select the most appropriate size
45 DEFPARAM (PARAM_SRA_MAX_STRUCTURE_SIZE,
46 "sra-max-structure-size",
47 "The maximum structure size (in bytes) for which GCC will "
48 "use by-element copies",
51 /* The maximum number of structure fields which the SRA pass will
52 instantiate to avoid block copies. The default value, 0, implies
53 that GCC will select the appropriate value itself. */
54 DEFPARAM (PARAM_SRA_MAX_STRUCTURE_COUNT,
55 "sra-max-structure-count",
56 "The maximum number of structure fields for which GCC will "
57 "use by-element copies",
60 /* The ratio between instantiated fields and the complete structure
61 size. We say that if the ratio of the number of bytes in
62 instantiated fields to the number of bytes in the complete
63 structure exceeds this parameter, or if the number of instantiated
64 fields to the total number of fields exceeds this parameter, then
65 block copies are not used. The default is 75%. */
66 DEFPARAM (PARAM_SRA_FIELD_STRUCTURE_RATIO,
67 "sra-field-structure-ratio",
68 "The threshold ratio between instantiated fields and the total structure size",
71 /* The threshold ratio between current and hottest structure counts.
72 We say that if the ratio of the current structure count,
73 calculated by profiling, to the hottest structure count
74 in the program is less than this parameter, then structure
75 reorganization is not applied. The default is 10%. */
76 DEFPARAM (PARAM_STRUCT_REORG_COLD_STRUCT_RATIO,
77 "struct-reorg-cold-struct-ratio",
78 "The threshold ratio between current and hottest structure counts",
81 /* When branch is predicted to be taken with probability lower than this
82 threshold (in percent), then it is considered well predictable. */
83 DEFPARAM (PARAM_PREDICTABLE_BRANCH_OUTCOME,
84 "predictable-branch-outcome",
85 "Maximal esitmated outcome of branch considered predictable",
88 /* The single function inlining limit. This is the maximum size
89 of a function counted in internal gcc instructions (not in
90 real machine instructions) that is eligible for inlining
92 The default value is 450.
93 Only functions marked inline (or methods defined in the class
94 definition for C++) are affected by this.
95 There are more restrictions to inlining: If inlined functions
96 call other functions, the already inlined instructions are
97 counted and once the recursive inline limit (see
98 "max-inline-insns" parameter) is exceeded, the acceptable size
100 DEFPARAM (PARAM_MAX_INLINE_INSNS_SINGLE,
101 "max-inline-insns-single",
102 "The maximum number of instructions in a single function eligible for inlining",
105 /* The single function inlining limit for functions that are
106 inlined by virtue of -finline-functions (-O3).
107 This limit should be chosen to be below or equal to the limit
108 that is applied to functions marked inlined (or defined in the
109 class declaration in C++) given by the "max-inline-insns-single"
111 The default value is 90. */
112 DEFPARAM (PARAM_MAX_INLINE_INSNS_AUTO,
113 "max-inline-insns-auto",
114 "The maximum number of instructions when automatically inlining",
117 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE,
118 "max-inline-insns-recursive",
119 "The maximum number of instructions inline function can grow to via recursive inlining",
122 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE_AUTO,
123 "max-inline-insns-recursive-auto",
124 "The maximum number of instructions non-inline function can grow to via recursive inlining",
127 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH,
128 "max-inline-recursive-depth",
129 "The maximum depth of recursive inlining for inline functions",
132 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH_AUTO,
133 "max-inline-recursive-depth-auto",
134 "The maximum depth of recursive inlining for non-inline functions",
137 DEFPARAM (PARAM_MIN_INLINE_RECURSIVE_PROBABILITY,
138 "min-inline-recursive-probability",
139 "Inline recursively only when the probability of call being executed exceeds the parameter",
142 /* Limit of iterations of early inliner. This basically bounds number of
143 nested indirect calls early inliner can resolve. Deeper chains are still
144 handled by late inlining. */
145 DEFPARAM (PARAM_EARLY_INLINER_MAX_ITERATIONS,
146 "max-early-inliner-iterations",
147 "The maximum number of nested indirect inlining performed by early inliner",
150 /* Limit the number of expansions created by the variable expansion
151 optimization to avoid register pressure. */
152 DEFPARAM (PARAM_MAX_VARIABLE_EXPANSIONS,
153 "max-variable-expansions-in-unroller",
154 "If -fvariable-expansion-in-unroller is used, the maximum number of times that an individual variable will be expanded during loop unrolling",
157 /* Limit loop autovectorization to loops with large enough iteration count. */
158 DEFPARAM (PARAM_MIN_VECT_LOOP_BOUND,
159 "min-vect-loop-bound",
160 "If -ftree-vectorize is used, the minimal loop bound of a loop to be considered for vectorization",
163 /* The maximum number of instructions to consider when looking for an
164 instruction to fill a delay slot. If more than this arbitrary
165 number of instructions is searched, the time savings from filling
166 the delay slot will be minimal so stop searching. Increasing
167 values mean more aggressive optimization, making the compile time
168 increase with probably small improvement in executable run time. */
169 DEFPARAM (PARAM_MAX_DELAY_SLOT_INSN_SEARCH,
170 "max-delay-slot-insn-search",
171 "The maximum number of instructions to consider to fill a delay slot",
174 /* When trying to fill delay slots, the maximum number of instructions
175 to consider when searching for a block with valid live register
176 information. Increasing this arbitrarily chosen value means more
177 aggressive optimization, increasing the compile time. This
178 parameter should be removed when the delay slot code is rewritten
179 to maintain the control-flow graph. */
180 DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
181 "max-delay-slot-live-search",
182 "The maximum number of instructions to consider to find accurate live register information",
185 /* This parameter limits the number of branch elements that the
186 scheduler will track anti-dependencies through without resetting
187 the tracking mechanism. Large functions with few calls or barriers
188 can generate lists containing many 1000's of dependencies. Generally
189 the compiler either uses all available memory, or runs for far too long. */
190 DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
191 "max-pending-list-length",
192 "The maximum length of scheduling's pending operations list",
195 DEFPARAM(PARAM_LARGE_FUNCTION_INSNS,
196 "large-function-insns",
197 "The size of function body to be considered large",
199 DEFPARAM(PARAM_LARGE_FUNCTION_GROWTH,
200 "large-function-growth",
201 "Maximal growth due to inlining of large function (in percent)",
203 DEFPARAM(PARAM_LARGE_UNIT_INSNS,
205 "The size of translation unit to be considered large",
207 DEFPARAM(PARAM_INLINE_UNIT_GROWTH,
208 "inline-unit-growth",
209 "how much can given compilation unit grow because of the inlining (in percent)",
211 DEFPARAM(PARAM_IPCP_UNIT_GROWTH,
213 "how much can given compilation unit grow because of the interprocedural constant propagation (in percent)",
215 DEFPARAM(PARAM_INLINE_CALL_COST,
217 "expense of call operation relative to ordinary arithmetic operations",
219 DEFPARAM(PARAM_LARGE_STACK_FRAME,
221 "The size of stack frame to be considered large",
223 DEFPARAM(PARAM_STACK_FRAME_GROWTH,
224 "large-stack-frame-growth",
225 "Maximal stack frame growth due to inlining (in percent)",
228 /* The GCSE optimization will be disabled if it would require
229 significantly more memory than this value. */
230 DEFPARAM(PARAM_MAX_GCSE_MEMORY,
232 "The maximum amount of memory to be allocated by GCSE",
233 50 * 1024 * 1024, 0, 0)
235 /* This is the threshold ratio when to perform partial redundancy
236 elimination after reload. We perform partial redundancy elimination
237 when the following holds:
238 (Redundant load execution count)
239 ------------------------------- >= GCSE_AFTER_RELOAD_PARTIAL_FRACTION
240 (Added loads execution count) */
241 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_PARTIAL_FRACTION,
242 "gcse-after-reload-partial-fraction",
243 "The threshold ratio for performing partial redundancy elimination after reload",
245 /* This is the threshold ratio of the critical edges execution count compared to
246 the redundant loads execution count that permits performing the load
247 redundancy elimination in gcse after reload. */
248 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_CRITICAL_FRACTION,
249 "gcse-after-reload-critical-fraction",
250 "The threshold ratio of critical edges execution count that permit performing redundancy elimination after reload",
252 /* This parameter limits the number of insns in a loop that will be unrolled,
253 and by how much the loop is unrolled.
255 This limit should be at most half of the peeling limits: loop unroller
256 decides to not unroll loops that iterate fewer than 2*number of allowed
257 unrollings and thus we would have loops that are neither peeled or unrolled
259 DEFPARAM(PARAM_MAX_UNROLLED_INSNS,
260 "max-unrolled-insns",
261 "The maximum number of instructions to consider to unroll in a loop",
263 /* This parameter limits how many times the loop is unrolled depending
264 on number of insns really executed in each iteration. */
265 DEFPARAM(PARAM_MAX_AVERAGE_UNROLLED_INSNS,
266 "max-average-unrolled-insns",
267 "The maximum number of instructions to consider to unroll in a loop on average",
269 /* The maximum number of unrollings of a single loop. */
270 DEFPARAM(PARAM_MAX_UNROLL_TIMES,
272 "The maximum number of unrollings of a single loop",
274 /* The maximum number of insns of a peeled loop. */
275 DEFPARAM(PARAM_MAX_PEELED_INSNS,
277 "The maximum number of insns of a peeled loop",
279 /* The maximum number of peelings of a single loop. */
280 DEFPARAM(PARAM_MAX_PEEL_TIMES,
282 "The maximum number of peelings of a single loop",
284 /* The maximum number of insns of a peeled loop. */
285 DEFPARAM(PARAM_MAX_COMPLETELY_PEELED_INSNS,
286 "max-completely-peeled-insns",
287 "The maximum number of insns of a completely peeled loop",
289 /* The maximum number of peelings of a single loop that is peeled completely. */
290 DEFPARAM(PARAM_MAX_COMPLETELY_PEEL_TIMES,
291 "max-completely-peel-times",
292 "The maximum number of peelings of a single loop that is peeled completely",
294 /* The maximum number of insns of a peeled loop that rolls only once. */
295 DEFPARAM(PARAM_MAX_ONCE_PEELED_INSNS,
296 "max-once-peeled-insns",
297 "The maximum number of insns of a peeled loop that rolls only once",
300 /* The maximum number of insns of an unswitched loop. */
301 DEFPARAM(PARAM_MAX_UNSWITCH_INSNS,
302 "max-unswitch-insns",
303 "The maximum number of insns of an unswitched loop",
305 /* The maximum level of recursion in unswitch_single_loop. */
306 DEFPARAM(PARAM_MAX_UNSWITCH_LEVEL,
307 "max-unswitch-level",
308 "The maximum number of unswitchings in a single loop",
311 /* The maximum number of iterations of a loop the brute force algorithm
312 for analysis of # of iterations of the loop tries to evaluate. */
313 DEFPARAM(PARAM_MAX_ITERATIONS_TO_TRACK,
314 "max-iterations-to-track",
315 "Bound on the number of iterations the brute force # of iterations analysis algorithm evaluates",
317 /* A cutoff to avoid costly computations of the number of iterations in
318 the doloop transformation. */
319 DEFPARAM(PARAM_MAX_ITERATIONS_COMPUTATION_COST,
320 "max-iterations-computation-cost",
321 "Bound on the cost of an expression to compute the number of iterations",
324 /* This parameter is used to tune SMS MAX II calculations. */
325 DEFPARAM(PARAM_SMS_MAX_II_FACTOR,
327 "A factor for tuning the upper bound that swing modulo scheduler uses for scheduling a loop",
329 DEFPARAM(PARAM_SMS_DFA_HISTORY,
331 "The number of cycles the swing modulo scheduler considers when checking conflicts using DFA",
333 DEFPARAM(PARAM_SMS_LOOP_AVERAGE_COUNT_THRESHOLD,
334 "sms-loop-average-count-threshold",
335 "A threshold on the average loop count considered by the swing modulo scheduler",
338 DEFPARAM(HOT_BB_COUNT_FRACTION,
339 "hot-bb-count-fraction",
340 "Select fraction of the maximal count of repetitions of basic block in program given basic block needs to have to be considered hot",
342 DEFPARAM(HOT_BB_FREQUENCY_FRACTION,
343 "hot-bb-frequency-fraction",
344 "Select fraction of the maximal frequency of executions of basic block in function given basic block needs to have to be considered hot",
347 DEFPARAM (PARAM_ALIGN_THRESHOLD,
349 "Select fraction of the maximal frequency of executions of basic block in function given basic block get alignment",
352 DEFPARAM (PARAM_ALIGN_LOOP_ITERATIONS,
353 "align-loop-iterations",
354 "Loops iterating at least selected number of iterations will get loop alignement.",
357 /* For guessed profiles, the loops having unknown number of iterations
358 are predicted to iterate relatively few (10) times at average.
359 For functions containing one loop with large known number of iterations
360 and other loops having unbounded loops we would end up predicting all
361 the other loops cold that is not usually the case. So we need to artificially
364 We need to cut the maximal predicted iterations to large enough iterations
365 so the loop appears important, but safely within HOT_BB_COUNT_FRACTION
368 DEFPARAM(PARAM_MAX_PREDICTED_ITERATIONS,
369 "max-predicted-iterations",
370 "The maximum number of loop iterations we predict statically",
372 DEFPARAM(TRACER_DYNAMIC_COVERAGE_FEEDBACK,
373 "tracer-dynamic-coverage-feedback",
374 "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is available",
376 DEFPARAM(TRACER_DYNAMIC_COVERAGE,
377 "tracer-dynamic-coverage",
378 "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is not available",
380 DEFPARAM(TRACER_MAX_CODE_GROWTH,
381 "tracer-max-code-growth",
382 "Maximal code growth caused by tail duplication (in percent)",
384 DEFPARAM(TRACER_MIN_BRANCH_RATIO,
385 "tracer-min-branch-ratio",
386 "Stop reverse growth if the reverse probability of best edge is less than this threshold (in percent)",
388 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK,
389 "tracer-min-branch-probability-feedback",
390 "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is available",
392 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY,
393 "tracer-min-branch-probability",
394 "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is not available",
397 /* The maximum number of incoming edges to consider for crossjumping. */
398 DEFPARAM(PARAM_MAX_CROSSJUMP_EDGES,
399 "max-crossjump-edges",
400 "The maximum number of incoming edges to consider for crossjumping",
403 /* The minimum number of matching instructions to consider for crossjumping. */
404 DEFPARAM(PARAM_MIN_CROSSJUMP_INSNS,
405 "min-crossjump-insns",
406 "The minimum number of matching instructions to consider for crossjumping",
409 /* The maximum number expansion factor when copying basic blocks. */
410 DEFPARAM(PARAM_MAX_GROW_COPY_BB_INSNS,
411 "max-grow-copy-bb-insns",
412 "The maximum expansion factor when copying basic blocks",
415 /* The maximum number of insns to duplicate when unfactoring computed gotos. */
416 DEFPARAM(PARAM_MAX_GOTO_DUPLICATION_INSNS,
417 "max-goto-duplication-insns",
418 "The maximum number of insns to duplicate when unfactoring computed gotos",
421 /* The maximum length of path considered in cse. */
422 DEFPARAM(PARAM_MAX_CSE_PATH_LENGTH,
423 "max-cse-path-length",
424 "The maximum length of path considered in cse",
426 DEFPARAM(PARAM_MAX_CSE_INSNS,
428 "The maximum instructions CSE process before flushing",
431 /* The cost of expression in loop invariant motion that is considered
433 DEFPARAM(PARAM_LIM_EXPENSIVE,
435 "The minimum cost of an expensive expression in the loop invariant motion",
438 /* Bound on number of candidates for induction variables below that
439 all candidates are considered for each use in induction variable
442 DEFPARAM(PARAM_IV_CONSIDER_ALL_CANDIDATES_BOUND,
443 "iv-consider-all-candidates-bound",
444 "Bound on number of candidates below that all candidates are considered in iv optimizations",
447 /* The induction variable optimizations give up on loops that contain more
448 induction variable uses. */
450 DEFPARAM(PARAM_IV_MAX_CONSIDERED_USES,
451 "iv-max-considered-uses",
452 "Bound on number of iv uses in loop optimized in iv optimizations",
455 /* If there are at most this number of ivs in the set, try removing unnecessary
456 ivs from the set always. */
458 DEFPARAM(PARAM_IV_ALWAYS_PRUNE_CAND_SET_BOUND,
459 "iv-always-prune-cand-set-bound",
460 "If number of candidates in the set is smaller, we always try to remove unused ivs during its optimization",
463 DEFPARAM(PARAM_SCEV_MAX_EXPR_SIZE,
464 "scev-max-expr-size",
465 "Bound on size of expressions used in the scalar evolutions analyzer",
468 DEFPARAM(PARAM_OMEGA_MAX_VARS,
470 "Bound on the number of variables in Omega constraint systems",
473 DEFPARAM(PARAM_OMEGA_MAX_GEQS,
475 "Bound on the number of inequalities in Omega constraint systems",
478 DEFPARAM(PARAM_OMEGA_MAX_EQS,
480 "Bound on the number of equalities in Omega constraint systems",
483 DEFPARAM(PARAM_OMEGA_MAX_WILD_CARDS,
484 "omega-max-wild-cards",
485 "Bound on the number of wild cards in Omega constraint systems",
488 DEFPARAM(PARAM_OMEGA_HASH_TABLE_SIZE,
489 "omega-hash-table-size",
490 "Bound on the size of the hash table in Omega constraint systems",
493 DEFPARAM(PARAM_OMEGA_MAX_KEYS,
495 "Bound on the number of keys in Omega constraint systems",
498 DEFPARAM(PARAM_OMEGA_ELIMINATE_REDUNDANT_CONSTRAINTS,
499 "omega-eliminate-redundant-constraints",
500 "When set to 1, use expensive methods to eliminate all redundant constraints",
503 DEFPARAM(PARAM_VECT_MAX_VERSION_FOR_ALIGNMENT_CHECKS,
504 "vect-max-version-for-alignment-checks",
505 "Bound on number of runtime checks inserted by the vectorizer's loop versioning for alignment check",
508 DEFPARAM(PARAM_VECT_MAX_VERSION_FOR_ALIAS_CHECKS,
509 "vect-max-version-for-alias-checks",
510 "Bound on number of runtime checks inserted by the vectorizer's loop versioning for alias check",
513 DEFPARAM(PARAM_MAX_CSELIB_MEMORY_LOCATIONS,
514 "max-cselib-memory-locations",
515 "The maximum memory locations recorded by cselib",
518 #ifdef ENABLE_GC_ALWAYS_COLLECT
519 # define GGC_MIN_EXPAND_DEFAULT 0
520 # define GGC_MIN_HEAPSIZE_DEFAULT 0
522 # define GGC_MIN_EXPAND_DEFAULT 30
523 # define GGC_MIN_HEAPSIZE_DEFAULT 4096
526 DEFPARAM(GGC_MIN_EXPAND,
528 "Minimum heap expansion to trigger garbage collection, as a percentage of the total size of the heap",
529 GGC_MIN_EXPAND_DEFAULT, 0, 0)
531 DEFPARAM(GGC_MIN_HEAPSIZE,
533 "Minimum heap size before we start collecting garbage, in kilobytes",
534 GGC_MIN_HEAPSIZE_DEFAULT, 0, 0)
536 #undef GGC_MIN_EXPAND_DEFAULT
537 #undef GGC_MIN_HEAPSIZE_DEFAULT
539 DEFPARAM(PARAM_MAX_RELOAD_SEARCH_INSNS,
540 "max-reload-search-insns",
541 "The maximum number of instructions to search backward when looking for equivalent reload",
544 DEFPARAM(PARAM_MAX_SCHED_REGION_BLOCKS,
545 "max-sched-region-blocks",
546 "The maximum number of blocks in a region to be considered for interblock scheduling",
549 DEFPARAM(PARAM_MAX_SCHED_REGION_INSNS,
550 "max-sched-region-insns",
551 "The maximum number of insns in a region to be considered for interblock scheduling",
554 DEFPARAM(PARAM_MAX_PIPELINE_REGION_BLOCKS,
555 "max-pipeline-region-blocks",
556 "The maximum number of blocks in a region to be considered for interblock scheduling",
559 DEFPARAM(PARAM_MAX_PIPELINE_REGION_INSNS,
560 "max-pipeline-region-insns",
561 "The maximum number of insns in a region to be considered for interblock scheduling",
564 DEFPARAM(PARAM_MIN_SPEC_PROB,
566 "The minimum probability of reaching a source block for interblock speculative scheduling",
569 DEFPARAM(PARAM_MAX_SCHED_EXTEND_REGIONS_ITERS,
570 "max-sched-extend-regions-iters",
571 "The maximum number of iterations through CFG to extend regions",
574 DEFPARAM(PARAM_MAX_SCHED_INSN_CONFLICT_DELAY,
575 "max-sched-insn-conflict-delay",
576 "The maximum conflict delay for an insn to be considered for speculative motion",
579 DEFPARAM(PARAM_SCHED_SPEC_PROB_CUTOFF,
580 "sched-spec-prob-cutoff",
581 "The minimal probability of speculation success (in percents), so that speculative insn will be scheduled.",
584 DEFPARAM(PARAM_SELSCHED_MAX_LOOKAHEAD,
585 "selsched-max-lookahead",
586 "The maximum size of the lookahead window of selective scheduling",
589 DEFPARAM(PARAM_SELSCHED_MAX_SCHED_TIMES,
590 "selsched-max-sched-times",
591 "Maximum number of times that an insn could be scheduled",
594 DEFPARAM(PARAM_SELSCHED_INSNS_TO_RENAME,
595 "selsched-insns-to-rename",
596 "Maximum number of instructions in the ready list that are considered eligible for renaming",
599 DEFPARAM (PARAM_SCHED_MEM_TRUE_DEP_COST,
600 "sched-mem-true-dep-cost",
601 "Minimal distance between possibly conflicting store and load",
604 DEFPARAM(PARAM_MAX_LAST_VALUE_RTL,
605 "max-last-value-rtl",
606 "The maximum number of RTL nodes that can be recorded as combiner's last value",
609 /* INTEGER_CST nodes are shared for values [{-1,0} .. N) for
610 {signed,unsigned} integral types. This determines N.
611 Experimentation shows 256 to be a good value. */
612 DEFPARAM (PARAM_INTEGER_SHARE_LIMIT,
613 "integer-share-limit",
614 "The upper bound for sharing integer constants",
617 /* Incremental SSA updates for virtual operands may be very slow if
618 there is a large number of mappings to process. In those cases, it
619 is faster to rewrite the virtual symbols from scratch as if they
620 had been recently introduced. This heuristic cannot be applied to
621 SSA mappings for real SSA names, only symbols kept in FUD chains.
623 PARAM_MIN_VIRTUAL_MAPPINGS specifies the minimum number of virtual
624 mappings that should be registered to trigger the heuristic.
626 PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO specifies the ratio between
627 mappings and symbols. If the number of virtual mappings is
628 PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO bigger than the number of
629 virtual symbols to be updated, then the updater switches to a full
630 update for those symbols. */
631 DEFPARAM (PARAM_MIN_VIRTUAL_MAPPINGS,
632 "min-virtual-mappings",
633 "Minimum number of virtual mappings to consider switching to full virtual renames",
636 DEFPARAM (PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO,
637 "virtual-mappings-ratio",
638 "Ratio between virtual mappings and virtual symbols to do full virtual renames",
641 DEFPARAM (PARAM_SSP_BUFFER_SIZE,
643 "The lower bound for a buffer to be considered for stack smashing protection",
646 /* When we thread through a block we have to make copies of the
647 statements within the block. Clearly for large blocks the code
650 PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS specifies the maximum number
651 of statements and PHI nodes allowed in a block which is going to
652 be duplicated for thread jumping purposes.
654 Some simple analysis showed that more than 99% of the jump
655 threading opportunities are for blocks with less than 15
656 statements. So we can get the benefits of jump threading
657 without excessive code bloat for pathological cases with the
658 throttle set at 15 statements. */
659 DEFPARAM (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS,
660 "max-jump-thread-duplication-stmts",
661 "Maximum number of statements allowed in a block that needs to be duplicated when threading jumps",
664 /* This is the maximum number of fields a variable may have before the pointer analysis machinery
665 will stop trying to treat it in a field-sensitive manner.
666 There are programs out there with thousands of fields per structure, and handling them
667 field-sensitively is not worth the cost. */
668 DEFPARAM (PARAM_MAX_FIELDS_FOR_FIELD_SENSITIVE,
669 "max-fields-for-field-sensitive",
670 "Maximum number of fields in a structure before pointer analysis treats the structure as a single variable",
673 DEFPARAM(PARAM_MAX_SCHED_READY_INSNS,
674 "max-sched-ready-insns",
675 "The maximum number of instructions ready to be issued to be considered by the scheduler during the first scheduling pass",
678 /* Prefetching and cache-optimizations related parameters. Default values are
679 usually set by machine description. */
681 /* The number of insns executed before prefetch is completed. */
683 DEFPARAM (PARAM_PREFETCH_LATENCY,
685 "The number of insns executed before prefetch is completed",
688 /* The number of prefetches that can run at the same time. */
690 DEFPARAM (PARAM_SIMULTANEOUS_PREFETCHES,
691 "simultaneous-prefetches",
692 "The number of prefetches that can run at the same time",
695 /* The size of L1 cache in kB. */
697 DEFPARAM (PARAM_L1_CACHE_SIZE,
699 "The size of L1 cache",
702 /* The size of L1 cache line in bytes. */
704 DEFPARAM (PARAM_L1_CACHE_LINE_SIZE,
705 "l1-cache-line-size",
706 "The size of L1 cache line",
709 /* The size of L2 cache in kB. */
711 DEFPARAM (PARAM_L2_CACHE_SIZE,
713 "The size of L2 cache",
716 /* Whether we should use canonical types rather than deep "structural"
717 type checking. Setting this value to 1 (the default) improves
718 compilation performance in the C++ and Objective-C++ front end;
719 this value should only be set to zero to work around bugs in the
720 canonical type system by disabling it. */
722 DEFPARAM (PARAM_USE_CANONICAL_TYPES,
723 "use-canonical-types",
724 "Whether to use canonical types",
727 DEFPARAM (PARAM_MAX_PARTIAL_ANTIC_LENGTH,
728 "max-partial-antic-length",
729 "Maximum length of partial antic set when performing tree pre optimization",
732 /* The following is used as a stop-gap limit for cases where really huge
733 SCCs blow up memory and compile-time use too much. If we hit this limit,
734 SCCVN and such FRE and PRE will be not done at all for the current
737 DEFPARAM (PARAM_SCCVN_MAX_SCC_SIZE,
738 "sccvn-max-scc-size",
739 "Maximum size of a SCC before SCCVN stops processing a function",
742 DEFPARAM (PARAM_IRA_MAX_LOOPS_NUM,
744 "max loops number for regional RA",
747 DEFPARAM (PARAM_IRA_MAX_CONFLICT_TABLE_SIZE,
748 "ira-max-conflict-table-size",
749 "max size of conflict table in MB",
752 /* Switch initialization conversion will refuse to create arrays that are
753 bigger than this parameter times the number of switch branches. */
755 DEFPARAM (PARAM_SWITCH_CONVERSION_BRANCH_RATIO,
756 "switch-conversion-max-branch-ratio",
757 "The maximum ratio between array size and switch branches for "
758 "a switch conversion to take place",
761 /* Avoid doing loop invariant motion on very large loops. */
763 DEFPARAM (PARAM_LOOP_INVARIANT_MAX_BBS_IN_LOOP,
764 "loop-invariant-max-bbs-in-loop",
765 "max basic blocks number in loop for loop invariant motion",