gcc/params.def

   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>.
   5
   6 This file is part of GCC.
   7
   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
  11 version.
  12
  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
  16 for more details.
  17
  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/>.  */
  21
  22 /* This file contains definitions for language-independent
  23    parameters.  The DEFPARAM macro takes 6 arguments:
  24
  25      - The enumeral corresponding to this parameter.
  26
  27      - The name that can be used to set this parameter using the
  28        command-line option `--param <name>=<value>'.
  29
  30      - A help string explaining how the parameter is used.
  31
  32      - A default value for the parameter.
  33
  34      - The minimum acceptable value for the parameter.
  35
  36      - The maximum acceptable value for the parameter (if greater than
  37      the minimum).
  38
  39    Be sure to add an entry to invoke.texi summarizing the parameter.  */
  40
  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
  44    itself.  */
  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",
  49           0, 0, 0)
  50
  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",
  58           0, 0, 0)
  59
  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",
  69           75, 0, 100)
  70
  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",
  79           10, 0, 100)
  80
  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",
  86           2, 0, 50)
  87
  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
  91    by the tree inliner.
  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
  99    gets decreased.  */
 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",
 103           450, 0, 0)
 104
 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"
 110    parameter.
 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",
 115           90, 0, 0)
 116
 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",
 120           450, 0, 0)
 121
 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",
 125           450, 0, 0)
 126
 127 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH,
 128           "max-inline-recursive-depth",
 129           "The maximum depth of recursive inlining for inline functions",
 130           8, 0, 0)
 131
 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",
 135           8, 0, 0)
 136
 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",
 140           10, 0, 0)
 141
 142 /* Limit the number of expansions created by the variable expansion
 143    optimization to avoid register pressure.  */
 144 DEFPARAM (PARAM_MAX_VARIABLE_EXPANSIONS,
 145           "max-variable-expansions-in-unroller",
 146           "If -fvariable-expansion-in-unroller is used, the maximum number of times that an individual variable will be expanded during loop unrolling",
 147           1, 0, 0)
 148
 149 /* Limit loop autovectorization to loops with large enough iteration count.  */
 150 DEFPARAM (PARAM_MIN_VECT_LOOP_BOUND,
 151           "min-vect-loop-bound",
 152           "If -ftree-vectorize is used, the minimal loop bound of a loop to be considered for vectorization",
 153           1, 1, 0)
 154
 155 /* The maximum number of instructions to consider when looking for an
 156    instruction to fill a delay slot.  If more than this arbitrary
 157    number of instructions is searched, the time savings from filling
 158    the delay slot will be minimal so stop searching.  Increasing
 159    values mean more aggressive optimization, making the compile time
 160    increase with probably small improvement in executable run time.  */
 161 DEFPARAM (PARAM_MAX_DELAY_SLOT_INSN_SEARCH,
 162           "max-delay-slot-insn-search",
 163           "The maximum number of instructions to consider to fill a delay slot",
 164           100, 0, 0)
 165
 166 /* When trying to fill delay slots, the maximum number of instructions
 167    to consider when searching for a block with valid live register
 168    information.  Increasing this arbitrarily chosen value means more
 169    aggressive optimization, increasing the compile time.  This
 170    parameter should be removed when the delay slot code is rewritten
 171    to maintain the control-flow graph.  */
 172 DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
 173          "max-delay-slot-live-search",
 174          "The maximum number of instructions to consider to find accurate live register information",
 175          333, 0, 0)
 176
 177 /* This parameter limits the number of branch elements that the
 178    scheduler will track anti-dependencies through without resetting
 179    the tracking mechanism.  Large functions with few calls or barriers
 180    can generate lists containing many 1000's of dependencies.  Generally
 181    the compiler either uses all available memory, or runs for far too long.  */
 182 DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
 183          "max-pending-list-length",
 184          "The maximum length of scheduling's pending operations list",
 185          32, 0, 0)
 186
 187 DEFPARAM(PARAM_LARGE_FUNCTION_INSNS,
 188          "large-function-insns",
 189          "The size of function body to be considered large",
 190          2700, 0, 0)
 191 DEFPARAM(PARAM_LARGE_FUNCTION_GROWTH,
 192          "large-function-growth",
 193          "Maximal growth due to inlining of large function (in percent)",
 194          100, 0, 0)
 195 DEFPARAM(PARAM_LARGE_UNIT_INSNS,
 196          "large-unit-insns",
 197          "The size of translation unit to be considered large",
 198          10000, 0, 0)
 199 DEFPARAM(PARAM_INLINE_UNIT_GROWTH,
 200          "inline-unit-growth",
 201          "how much can given compilation unit grow because of the inlining (in percent)",
 202          30, 0, 0)
 203 DEFPARAM(PARAM_IPCP_UNIT_GROWTH,
 204          "ipcp-unit-growth",
 205          "how much can given compilation unit grow because of the interprocedural constant propagation (in percent)",
 206          10, 0, 0)
 207 DEFPARAM(PARAM_INLINE_CALL_COST,
 208          "inline-call-cost",
 209          "expense of call operation relative to ordinary arithmetic operations",
 210          12, 0, 0)
 211 DEFPARAM(PARAM_LARGE_STACK_FRAME,
 212          "large-stack-frame",
 213          "The size of stack frame to be considered large",
 214          256, 0, 0)
 215 DEFPARAM(PARAM_STACK_FRAME_GROWTH,
 216          "large-stack-frame-growth",
 217          "Maximal stack frame growth due to inlining (in percent)",
 218          1000, 0, 0)
 219
 220 /* The GCSE optimization will be disabled if it would require
 221    significantly more memory than this value.  */
 222 DEFPARAM(PARAM_MAX_GCSE_MEMORY,
 223          "max-gcse-memory",
 224          "The maximum amount of memory to be allocated by GCSE",
 225          50 * 1024 * 1024, 0, 0)
 226
 227 /* This is the threshold ratio when to perform partial redundancy
 228    elimination after reload. We perform partial redundancy elimination
 229    when the following holds:
 230    (Redundant load execution count)
 231    ------------------------------- >= GCSE_AFTER_RELOAD_PARTIAL_FRACTION
 232    (Added loads execution count)                                          */
 233 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_PARTIAL_FRACTION,
 234         "gcse-after-reload-partial-fraction",
 235         "The threshold ratio for performing partial redundancy elimination after reload",
 236         3, 0, 0)
 237 /* This is the threshold ratio of the critical edges execution count compared to
 238    the redundant loads execution count that permits performing the load
 239    redundancy elimination in gcse after reload.  */
 240 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_CRITICAL_FRACTION,
 241         "gcse-after-reload-critical-fraction",
 242         "The threshold ratio of critical edges execution count that permit performing redundancy elimination after reload",
 243         10, 0, 0)
 244 /* This parameter limits the number of insns in a loop that will be unrolled,
 245    and by how much the loop is unrolled.
 246
 247    This limit should be at most half of the peeling limits:  loop unroller
 248    decides to not unroll loops that iterate fewer than 2*number of allowed
 249    unrollings and thus we would have loops that are neither peeled or unrolled
 250    otherwise.  */
 251 DEFPARAM(PARAM_MAX_UNROLLED_INSNS,
 252          "max-unrolled-insns",
 253          "The maximum number of instructions to consider to unroll in a loop",
 254          200, 0, 0)
 255 /* This parameter limits how many times the loop is unrolled depending
 256    on number of insns really executed in each iteration.  */
 257 DEFPARAM(PARAM_MAX_AVERAGE_UNROLLED_INSNS,
 258          "max-average-unrolled-insns",
 259          "The maximum number of instructions to consider to unroll in a loop on average",
 260          80, 0, 0)
 261 /* The maximum number of unrollings of a single loop.  */
 262 DEFPARAM(PARAM_MAX_UNROLL_TIMES,
 263         "max-unroll-times",
 264         "The maximum number of unrollings of a single loop",
 265         8, 0, 0)
 266 /* The maximum number of insns of a peeled loop.  */
 267 DEFPARAM(PARAM_MAX_PEELED_INSNS,
 268         "max-peeled-insns",
 269         "The maximum number of insns of a peeled loop",
 270         400, 0, 0)
 271 /* The maximum number of peelings of a single loop.  */
 272 DEFPARAM(PARAM_MAX_PEEL_TIMES,
 273         "max-peel-times",
 274         "The maximum number of peelings of a single loop",
 275         16, 0, 0)
 276 /* The maximum number of insns of a peeled loop.  */
 277 DEFPARAM(PARAM_MAX_COMPLETELY_PEELED_INSNS,
 278         "max-completely-peeled-insns",
 279         "The maximum number of insns of a completely peeled loop",
 280         400, 0, 0)
 281 /* The maximum number of peelings of a single loop that is peeled completely.  */
 282 DEFPARAM(PARAM_MAX_COMPLETELY_PEEL_TIMES,
 283         "max-completely-peel-times",
 284         "The maximum number of peelings of a single loop that is peeled completely",
 285         16, 0, 0)
 286 /* The maximum number of insns of a peeled loop that rolls only once.  */
 287 DEFPARAM(PARAM_MAX_ONCE_PEELED_INSNS,
 288         "max-once-peeled-insns",
 289         "The maximum number of insns of a peeled loop that rolls only once",
 290         400, 0, 0)
 291
 292 /* The maximum number of insns of an unswitched loop.  */
 293 DEFPARAM(PARAM_MAX_UNSWITCH_INSNS,
 294         "max-unswitch-insns",
 295         "The maximum number of insns of an unswitched loop",
 296         50, 0, 0)
 297 /* The maximum level of recursion in unswitch_single_loop.  */
 298 DEFPARAM(PARAM_MAX_UNSWITCH_LEVEL,
 299         "max-unswitch-level",
 300         "The maximum number of unswitchings in a single loop",
 301         3, 0, 0)
 302
 303 /* The maximum number of iterations of a loop the brute force algorithm
 304    for analysis of # of iterations of the loop tries to evaluate.  */
 305 DEFPARAM(PARAM_MAX_ITERATIONS_TO_TRACK,
 306         "max-iterations-to-track",
 307         "Bound on the number of iterations the brute force # of iterations analysis algorithm evaluates",
 308         1000, 0, 0)
 309 /* A cutoff to avoid costly computations of the number of iterations in
 310    the doloop transformation.  */
 311 DEFPARAM(PARAM_MAX_ITERATIONS_COMPUTATION_COST,
 312         "max-iterations-computation-cost",
 313         "Bound on the cost of an expression to compute the number of iterations",
 314         10, 0, 0)
 315
 316 /* This parameter is used to tune SMS MAX II calculations.  */
 317 DEFPARAM(PARAM_SMS_MAX_II_FACTOR,
 318          "sms-max-ii-factor",
 319          "A factor for tuning the upper bound that swing modulo scheduler uses for scheduling a loop",
 320          100, 0, 0)
 321 DEFPARAM(PARAM_SMS_DFA_HISTORY,
 322          "sms-dfa-history",
 323          "The number of cycles the swing modulo scheduler considers when checking conflicts using DFA",
 324          0, 0, 0)
 325 DEFPARAM(PARAM_SMS_LOOP_AVERAGE_COUNT_THRESHOLD,
 326          "sms-loop-average-count-threshold",
 327          "A threshold on the average loop count considered by the swing modulo scheduler",
 328          0, 0, 0)
 329
 330 DEFPARAM(HOT_BB_COUNT_FRACTION,
 331          "hot-bb-count-fraction",
 332          "Select fraction of the maximal count of repetitions of basic block in program given basic block needs to have to be considered hot",
 333          10000, 0, 0)
 334 DEFPARAM(HOT_BB_FREQUENCY_FRACTION,
 335          "hot-bb-frequency-fraction",
 336          "Select fraction of the maximal frequency of executions of basic block in function given basic block needs to have to be considered hot",
 337          1000, 0, 0)
 338
 339 DEFPARAM (PARAM_ALIGN_THRESHOLD,
 340           "align-threshold",
 341           "Select fraction of the maximal frequency of executions of basic block in function given basic block get alignment",
 342           100, 0, 0)
 343
 344 DEFPARAM (PARAM_ALIGN_LOOP_ITERATIONS,
 345           "align-loop-iterations",
 346           "Loops iterating at least selected number of iterations will get loop alignement.",
 347           4, 0, 0)
 348
 349 /* For guessed profiles, the loops having unknown number of iterations
 350    are predicted to iterate relatively few (10) times at average.
 351    For functions containing one loop with large known number of iterations
 352    and other loops having unbounded loops we would end up predicting all
 353    the other loops cold that is not usually the case.  So we need to artificially
 354    flatten the profile.
 355
 356    We need to cut the maximal predicted iterations to large enough iterations
 357    so the loop appears important, but safely within HOT_BB_COUNT_FRACTION
 358    range.  */
 359
 360 DEFPARAM(PARAM_MAX_PREDICTED_ITERATIONS,
 361          "max-predicted-iterations",
 362          "The maximum number of loop iterations we predict statically",
 363          100, 0, 0)
 364 DEFPARAM(TRACER_DYNAMIC_COVERAGE_FEEDBACK,
 365          "tracer-dynamic-coverage-feedback",
 366          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is available",
 367          95, 0, 100)
 368 DEFPARAM(TRACER_DYNAMIC_COVERAGE,
 369          "tracer-dynamic-coverage",
 370          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is not available",
 371          75, 0, 100)
 372 DEFPARAM(TRACER_MAX_CODE_GROWTH,
 373          "tracer-max-code-growth",
 374          "Maximal code growth caused by tail duplication (in percent)",
 375          100, 0, 0)
 376 DEFPARAM(TRACER_MIN_BRANCH_RATIO,
 377          "tracer-min-branch-ratio",
 378          "Stop reverse growth if the reverse probability of best edge is less than this threshold (in percent)",
 379          10, 0, 100)
 380 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK,
 381          "tracer-min-branch-probability-feedback",
 382          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is available",
 383          80, 0, 100)
 384 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY,
 385          "tracer-min-branch-probability",
 386          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is not available",
 387          50, 0, 100)
 388
 389 /* The maximum number of incoming edges to consider for crossjumping.  */
 390 DEFPARAM(PARAM_MAX_CROSSJUMP_EDGES,
 391          "max-crossjump-edges",
 392          "The maximum number of incoming edges to consider for crossjumping",
 393          100, 0, 0)
 394
 395 /* The minimum number of matching instructions to consider for crossjumping.  */
 396 DEFPARAM(PARAM_MIN_CROSSJUMP_INSNS,
 397      "min-crossjump-insns",
 398      "The minimum number of matching instructions to consider for crossjumping",
 399      5, 0, 0)
 400
 401 /* The maximum number expansion factor when copying basic blocks.  */
 402 DEFPARAM(PARAM_MAX_GROW_COPY_BB_INSNS,
 403      "max-grow-copy-bb-insns",
 404      "The maximum expansion factor when copying basic blocks",
 405      8, 0, 0)
 406
 407 /* The maximum number of insns to duplicate when unfactoring computed gotos.  */
 408 DEFPARAM(PARAM_MAX_GOTO_DUPLICATION_INSNS,
 409      "max-goto-duplication-insns",
 410      "The maximum number of insns to duplicate when unfactoring computed gotos",
 411      8, 0, 0)
 412
 413 /* The maximum length of path considered in cse.  */
 414 DEFPARAM(PARAM_MAX_CSE_PATH_LENGTH,
 415          "max-cse-path-length",
 416          "The maximum length of path considered in cse",
 417          10, 0, 0)
 418 DEFPARAM(PARAM_MAX_CSE_INSNS,
 419          "max-cse-insns",
 420          "The maximum instructions CSE process before flushing",
 421          1000, 0, 0)
 422
 423 /* The cost of expression in loop invariant motion that is considered
 424    expensive.  */
 425 DEFPARAM(PARAM_LIM_EXPENSIVE,
 426          "lim-expensive",
 427          "The minimum cost of an expensive expression in the loop invariant motion",
 428          20, 0, 0)
 429
 430 /* Bound on number of candidates for induction variables below that
 431    all candidates are considered for each use in induction variable
 432    optimizations.  */
 433
 434 DEFPARAM(PARAM_IV_CONSIDER_ALL_CANDIDATES_BOUND,
 435          "iv-consider-all-candidates-bound",
 436          "Bound on number of candidates below that all candidates are considered in iv optimizations",
 437          30, 0, 0)
 438
 439 /* The induction variable optimizations give up on loops that contain more
 440    induction variable uses.  */
 441
 442 DEFPARAM(PARAM_IV_MAX_CONSIDERED_USES,
 443          "iv-max-considered-uses",
 444          "Bound on number of iv uses in loop optimized in iv optimizations",
 445          250, 0, 0)
 446
 447 /* If there are at most this number of ivs in the set, try removing unnecessary
 448    ivs from the set always.  */
 449
 450 DEFPARAM(PARAM_IV_ALWAYS_PRUNE_CAND_SET_BOUND,
 451          "iv-always-prune-cand-set-bound",
 452          "If number of candidates in the set is smaller, we always try to remove unused ivs during its optimization",
 453          10, 0, 0)
 454
 455 DEFPARAM(PARAM_SCEV_MAX_EXPR_SIZE,
 456          "scev-max-expr-size",
 457          "Bound on size of expressions used in the scalar evolutions analyzer",
 458          20, 0, 0)
 459
 460 DEFPARAM(PARAM_OMEGA_MAX_VARS,
 461          "omega-max-vars",
 462          "Bound on the number of variables in Omega constraint systems",
 463          128, 0, 0)
 464
 465 DEFPARAM(PARAM_OMEGA_MAX_GEQS,
 466          "omega-max-geqs",
 467          "Bound on the number of inequalities in Omega constraint systems",
 468          256, 0, 0)
 469
 470 DEFPARAM(PARAM_OMEGA_MAX_EQS,
 471          "omega-max-eqs",
 472          "Bound on the number of equalities in Omega constraint systems",
 473          128, 0, 0)
 474
 475 DEFPARAM(PARAM_OMEGA_MAX_WILD_CARDS,
 476          "omega-max-wild-cards",
 477          "Bound on the number of wild cards in Omega constraint systems",
 478          18, 0, 0)
 479
 480 DEFPARAM(PARAM_OMEGA_HASH_TABLE_SIZE,
 481          "omega-hash-table-size",
 482          "Bound on the size of the hash table in Omega constraint systems",
 483          550, 0, 0)
 484
 485 DEFPARAM(PARAM_OMEGA_MAX_KEYS,
 486          "omega-max-keys",
 487          "Bound on the number of keys in Omega constraint systems",
 488          500, 0, 0)
 489
 490 DEFPARAM(PARAM_OMEGA_ELIMINATE_REDUNDANT_CONSTRAINTS,
 491          "omega-eliminate-redundant-constraints",
 492          "When set to 1, use expensive methods to eliminate all redundant constraints",
 493          0, 0, 1)
 494
 495 DEFPARAM(PARAM_VECT_MAX_VERSION_FOR_ALIGNMENT_CHECKS,
 496          "vect-max-version-for-alignment-checks",
 497          "Bound on number of runtime checks inserted by the vectorizer's loop versioning for alignment check",
 498          6, 0, 0)
 499
 500 DEFPARAM(PARAM_VECT_MAX_VERSION_FOR_ALIAS_CHECKS,
 501          "vect-max-version-for-alias-checks",
 502          "Bound on number of runtime checks inserted by the vectorizer's loop versioning for alias check",
 503          10, 0, 0)
 504
 505 DEFPARAM(PARAM_MAX_CSELIB_MEMORY_LOCATIONS,
 506          "max-cselib-memory-locations",
 507          "The maximum memory locations recorded by cselib",
 508          500, 0, 0)
 509
 510 #ifdef ENABLE_GC_ALWAYS_COLLECT
 511 # define GGC_MIN_EXPAND_DEFAULT 0
 512 # define GGC_MIN_HEAPSIZE_DEFAULT 0
 513 #else
 514 # define GGC_MIN_EXPAND_DEFAULT 30
 515 # define GGC_MIN_HEAPSIZE_DEFAULT 4096
 516 #endif
 517
 518 DEFPARAM(GGC_MIN_EXPAND,
 519          "ggc-min-expand",
 520          "Minimum heap expansion to trigger garbage collection, as a percentage of the total size of the heap",
 521          GGC_MIN_EXPAND_DEFAULT, 0, 0)
 522
 523 DEFPARAM(GGC_MIN_HEAPSIZE,
 524          "ggc-min-heapsize",
 525          "Minimum heap size before we start collecting garbage, in kilobytes",
 526          GGC_MIN_HEAPSIZE_DEFAULT, 0, 0)
 527
 528 #undef GGC_MIN_EXPAND_DEFAULT
 529 #undef GGC_MIN_HEAPSIZE_DEFAULT
 530
 531 DEFPARAM(PARAM_MAX_RELOAD_SEARCH_INSNS,
 532          "max-reload-search-insns",
 533          "The maximum number of instructions to search backward when looking for equivalent reload",
 534          100, 0, 0)
 535
 536 DEFPARAM(PARAM_MAX_SCHED_REGION_BLOCKS,
 537          "max-sched-region-blocks",
 538          "The maximum number of blocks in a region to be considered for interblock scheduling",
 539          10, 0, 0)
 540
 541 DEFPARAM(PARAM_MAX_SCHED_REGION_INSNS,
 542          "max-sched-region-insns",
 543          "The maximum number of insns in a region to be considered for interblock scheduling",
 544          100, 0, 0)
 545
 546 DEFPARAM(PARAM_MAX_PIPELINE_REGION_BLOCKS,
 547          "max-pipeline-region-blocks",
 548          "The maximum number of blocks in a region to be considered for interblock scheduling",
 549          15, 0, 0)
 550
 551 DEFPARAM(PARAM_MAX_PIPELINE_REGION_INSNS,
 552          "max-pipeline-region-insns",
 553          "The maximum number of insns in a region to be considered for interblock scheduling",
 554          200, 0, 0)
 555
 556 DEFPARAM(PARAM_MIN_SPEC_PROB,
 557          "min-spec-prob",
 558          "The minimum probability of reaching a source block for interblock speculative scheduling",
 559          40, 0, 0)
 560
 561 DEFPARAM(PARAM_MAX_SCHED_EXTEND_REGIONS_ITERS,
 562          "max-sched-extend-regions-iters",
 563          "The maximum number of iterations through CFG to extend regions",
 564          0, 0, 0)
 565
 566 DEFPARAM(PARAM_MAX_SCHED_INSN_CONFLICT_DELAY,
 567          "max-sched-insn-conflict-delay",
 568          "The maximum conflict delay for an insn to be considered for speculative motion",
 569          3, 1, 10)
 570
 571 DEFPARAM(PARAM_SCHED_SPEC_PROB_CUTOFF,
 572          "sched-spec-prob-cutoff",
 573          "The minimal probability of speculation success (in percents), so that speculative insn will be scheduled.",
 574          40, 0, 100)
 575
 576 DEFPARAM(PARAM_SELSCHED_MAX_LOOKAHEAD,
 577          "selsched-max-lookahead",
 578          "The maximum size of the lookahead window of selective scheduling",
 579          50, 0, 0)
 580
 581 DEFPARAM(PARAM_SELSCHED_MAX_SCHED_TIMES,
 582          "selsched-max-sched-times",
 583          "Maximum number of times that an insn could be scheduled",
 584          2, 0, 0)
 585
 586 DEFPARAM(PARAM_SELSCHED_INSNS_TO_RENAME,
 587          "selsched-insns-to-rename",
 588          "Maximum number of instructions in the ready list that are considered eligible for renaming",
 589          2, 0, 0)
 590
 591 DEFPARAM (PARAM_SCHED_MEM_TRUE_DEP_COST,
 592           "sched-mem-true-dep-cost",
 593           "Minimal distance between possibly conflicting store and load",
 594           1, 0, 0)
 595
 596 DEFPARAM(PARAM_MAX_LAST_VALUE_RTL,
 597          "max-last-value-rtl",
 598          "The maximum number of RTL nodes that can be recorded as combiner's last value",
 599          10000, 0, 0)
 600
 601 /* INTEGER_CST nodes are shared for values [{-1,0} .. N) for
 602    {signed,unsigned} integral types.  This determines N.
 603    Experimentation shows 256 to be a good value.  */
 604 DEFPARAM (PARAM_INTEGER_SHARE_LIMIT,
 605           "integer-share-limit",
 606           "The upper bound for sharing integer constants",
 607           256, 2, 2)
 608
 609 /* Incremental SSA updates for virtual operands may be very slow if
 610    there is a large number of mappings to process.  In those cases, it
 611    is faster to rewrite the virtual symbols from scratch as if they
 612    had been recently introduced.  This heuristic cannot be applied to
 613    SSA mappings for real SSA names, only symbols kept in FUD chains.
 614
 615    PARAM_MIN_VIRTUAL_MAPPINGS specifies the minimum number of virtual
 616    mappings that should be registered to trigger the heuristic.
 617
 618    PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO specifies the ratio between
 619    mappings and symbols.  If the number of virtual mappings is
 620    PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO bigger than the number of
 621    virtual symbols to be updated, then the updater switches to a full
 622    update for those symbols.  */
 623 DEFPARAM (PARAM_MIN_VIRTUAL_MAPPINGS,
 624           "min-virtual-mappings",
 625           "Minimum number of virtual mappings to consider switching to full virtual renames",
 626           100, 0, 0)
 627
 628 DEFPARAM (PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO,
 629           "virtual-mappings-ratio",
 630           "Ratio between virtual mappings and virtual symbols to do full virtual renames",
 631           3, 0, 0)
 632
 633 DEFPARAM (PARAM_SSP_BUFFER_SIZE,
 634           "ssp-buffer-size",
 635           "The lower bound for a buffer to be considered for stack smashing protection",
 636           8, 1, 0)
 637
 638 /* When we thread through a block we have to make copies of the
 639    statements within the block.  Clearly for large blocks the code
 640    duplication is bad.
 641
 642    PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS specifies the maximum number
 643    of statements and PHI nodes allowed in a block which is going to
 644    be duplicated for thread jumping purposes.
 645
 646    Some simple analysis showed that more than 99% of the jump
 647    threading opportunities are for blocks with less than 15
 648    statements.  So we can get the benefits of jump threading
 649    without excessive code bloat for pathological cases with the
 650    throttle set at 15 statements.  */
 651 DEFPARAM (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS,
 652           "max-jump-thread-duplication-stmts",
 653           "Maximum number of statements allowed in a block that needs to be duplicated when threading jumps",
 654           15, 0, 0)
 655
 656 /* This is the maximum number of fields a variable may have before the pointer analysis machinery
 657    will stop trying to treat it in a field-sensitive manner.
 658    There are programs out there with thousands of fields per structure, and handling them
 659    field-sensitively is not worth the cost.  */
 660 DEFPARAM (PARAM_MAX_FIELDS_FOR_FIELD_SENSITIVE,
 661           "max-fields-for-field-sensitive",
 662           "Maximum number of fields in a structure before pointer analysis treats the structure as a single variable",
 663           0, 0, 0)
 664
 665 DEFPARAM(PARAM_MAX_SCHED_READY_INSNS,
 666          "max-sched-ready-insns",
 667          "The maximum number of instructions ready to be issued to be considered by the scheduler during the first scheduling pass",
 668          100, 0, 0)
 669
 670 /* Prefetching and cache-optimizations related parameters.  Default values are
 671    usually set by machine description.  */
 672
 673 /* The number of insns executed before prefetch is completed.  */
 674
 675 DEFPARAM (PARAM_PREFETCH_LATENCY,
 676          "prefetch-latency",
 677          "The number of insns executed before prefetch is completed",
 678          200, 0, 0)
 679
 680 /* The number of prefetches that can run at the same time.  */
 681
 682 DEFPARAM (PARAM_SIMULTANEOUS_PREFETCHES,
 683           "simultaneous-prefetches",
 684           "The number of prefetches that can run at the same time",
 685           3, 0, 0)
 686
 687 /* The size of L1 cache in kB.  */
 688
 689 DEFPARAM (PARAM_L1_CACHE_SIZE,
 690           "l1-cache-size",
 691           "The size of L1 cache",
 692           64, 0, 0)
 693
 694 /* The size of L1 cache line in bytes.  */
 695
 696 DEFPARAM (PARAM_L1_CACHE_LINE_SIZE,
 697           "l1-cache-line-size",
 698           "The size of L1 cache line",
 699           32, 0, 0)
 700
 701 /* The size of L2 cache in kB.  */
 702
 703 DEFPARAM (PARAM_L2_CACHE_SIZE,
 704           "l2-cache-size",
 705           "The size of L2 cache",
 706           512, 0, 0)
 707
 708 /* Whether we should use canonical types rather than deep "structural"
 709    type checking.  Setting this value to 1 (the default) improves
 710    compilation performance in the C++ and Objective-C++ front end;
 711    this value should only be set to zero to work around bugs in the
 712    canonical type system by disabling it.  */
 713
 714 DEFPARAM (PARAM_USE_CANONICAL_TYPES,
 715           "use-canonical-types",
 716           "Whether to use canonical types",
 717           1, 0, 1)
 718
 719 DEFPARAM (PARAM_MAX_PARTIAL_ANTIC_LENGTH,
 720           "max-partial-antic-length",
 721           "Maximum length of partial antic set when performing tree pre optimization",
 722           100, 0, 0)
 723
 724 /* The following is used as a stop-gap limit for cases where really huge
 725    SCCs blow up memory and compile-time use too much.  If we hit this limit,
 726    SCCVN and such FRE and PRE will be not done at all for the current
 727    function.  */
 728
 729 DEFPARAM (PARAM_SCCVN_MAX_SCC_SIZE,
 730           "sccvn-max-scc-size",
 731           "Maximum size of a SCC before SCCVN stops processing a function",
 732           10000, 10, 0)
 733
 734 DEFPARAM (PARAM_IRA_MAX_LOOPS_NUM,
 735           "ira-max-loops-num",
 736           "max loops number for regional RA",
 737           100, 0, 0)
 738
 739 DEFPARAM (PARAM_IRA_MAX_CONFLICT_TABLE_SIZE,
 740           "ira-max-conflict-table-size",
 741           "max size of conflict table in MB",
 742           1000, 0, 0)
 743
 744 /* Switch initialization conversion will refuse to create arrays that are
 745    bigger than this parameter times the number of switch branches.  */
 746
 747 DEFPARAM (PARAM_SWITCH_CONVERSION_BRANCH_RATIO,
 748           "switch-conversion-max-branch-ratio",
 749           "The maximum ratio between array size and switch branches for "
 750           "a switch conversion to take place",
 751           8, 1, 0)
 752
 753 /* Avoid doing loop invariant motion on very large loops.  */
 754
 755 DEFPARAM (PARAM_LOOP_INVARIANT_MAX_BBS_IN_LOOP,
 756           "loop-invariant-max-bbs-in-loop",
 757           "max basic blocks number in loop for loop invariant motion",
 758           10000, 0, 0)
 759
 760 /*
 761 Local variables:
 762 mode:c
 763 End:
 764 */