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 threshold ratio between current and hottest structure counts.
  42    We say that if the ratio of the current structure count,
  43    calculated by profiling, to the hottest structure count
  44    in the program is less than this parameter, then structure
  45    reorganization is not applied. The default is 10%.  */
  46 DEFPARAM (PARAM_STRUCT_REORG_COLD_STRUCT_RATIO,
  47           "struct-reorg-cold-struct-ratio",
  48           "The threshold ratio between current and hottest structure counts",
  49           10, 0, 100)
  50
  51 /* When branch is predicted to be taken with probability lower than this
  52    threshold (in percent), then it is considered well predictable. */
  53 DEFPARAM (PARAM_PREDICTABLE_BRANCH_OUTCOME,
  54           "predictable-branch-outcome",
  55           "Maximal estimated outcome of branch considered predictable",
  56           2, 0, 50)
  57
  58 /* The single function inlining limit. This is the maximum size
  59    of a function counted in internal gcc instructions (not in
  60    real machine instructions) that is eligible for inlining
  61    by the tree inliner.
  62    The default value is 450.
  63    Only functions marked inline (or methods defined in the class
  64    definition for C++) are affected by this.
  65    There are more restrictions to inlining: If inlined functions
  66    call other functions, the already inlined instructions are
  67    counted and once the recursive inline limit (see
  68    "max-inline-insns" parameter) is exceeded, the acceptable size
  69    gets decreased.  */
  70 DEFPARAM (PARAM_MAX_INLINE_INSNS_SINGLE,
  71           "max-inline-insns-single",
  72           "The maximum number of instructions in a single function eligible for inlining",
  73           400, 0, 0)
  74
  75 /* The single function inlining limit for functions that are
  76    inlined by virtue of -finline-functions (-O3).
  77    This limit should be chosen to be below or equal to the limit
  78    that is applied to functions marked inlined (or defined in the
  79    class declaration in C++) given by the "max-inline-insns-single"
  80    parameter.
  81    The default value is 90.  */
  82 DEFPARAM (PARAM_MAX_INLINE_INSNS_AUTO,
  83           "max-inline-insns-auto",
  84           "The maximum number of instructions when automatically inlining",
  85           50, 0, 0)
  86
  87 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE,
  88           "max-inline-insns-recursive",
  89           "The maximum number of instructions inline function can grow to via recursive inlining",
  90           450, 0, 0)
  91
  92 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE_AUTO,
  93           "max-inline-insns-recursive-auto",
  94           "The maximum number of instructions non-inline function can grow to via recursive inlining",
  95           450, 0, 0)
  96
  97 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH,
  98           "max-inline-recursive-depth",
  99           "The maximum depth of recursive inlining for inline functions",
 100           8, 0, 0)
 101
 102 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH_AUTO,
 103           "max-inline-recursive-depth-auto",
 104           "The maximum depth of recursive inlining for non-inline functions",
 105           8, 0, 0)
 106
 107 DEFPARAM (PARAM_MIN_INLINE_RECURSIVE_PROBABILITY,
 108           "min-inline-recursive-probability",
 109           "Inline recursively only when the probability of call being executed exceeds the parameter",
 110           10, 0, 0)
 111
 112 /* Limit of iterations of early inliner.  This basically bounds number of
 113    nested indirect calls early inliner can resolve.  Deeper chains are still
 114    handled by late inlining.  */
 115 DEFPARAM (PARAM_EARLY_INLINER_MAX_ITERATIONS,
 116           "max-early-inliner-iterations",
 117           "The maximum number of nested indirect inlining performed by early inliner",
 118           10, 0, 0)
 119
 120 /* Limit the number of expansions created by the variable expansion
 121    optimization to avoid register pressure.  */
 122 DEFPARAM (PARAM_MAX_VARIABLE_EXPANSIONS,
 123           "max-variable-expansions-in-unroller",
 124           "If -fvariable-expansion-in-unroller is used, the maximum number of times that an individual variable will be expanded during loop unrolling",
 125           1, 0, 0)
 126
 127 /* Limit loop autovectorization to loops with large enough iteration count.  */
 128 DEFPARAM (PARAM_MIN_VECT_LOOP_BOUND,
 129           "min-vect-loop-bound",
 130           "If -ftree-vectorize is used, the minimal loop bound of a loop to be considered for vectorization",
 131           1, 1, 0)
 132
 133 /* The maximum number of instructions to consider when looking for an
 134    instruction to fill a delay slot.  If more than this arbitrary
 135    number of instructions is searched, the time savings from filling
 136    the delay slot will be minimal so stop searching.  Increasing
 137    values mean more aggressive optimization, making the compile time
 138    increase with probably small improvement in executable run time.  */
 139 DEFPARAM (PARAM_MAX_DELAY_SLOT_INSN_SEARCH,
 140           "max-delay-slot-insn-search",
 141           "The maximum number of instructions to consider to fill a delay slot",
 142           100, 0, 0)
 143
 144 /* When trying to fill delay slots, the maximum number of instructions
 145    to consider when searching for a block with valid live register
 146    information.  Increasing this arbitrarily chosen value means more
 147    aggressive optimization, increasing the compile time.  This
 148    parameter should be removed when the delay slot code is rewritten
 149    to maintain the control-flow graph.  */
 150 DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
 151          "max-delay-slot-live-search",
 152          "The maximum number of instructions to consider to find accurate live register information",
 153          333, 0, 0)
 154
 155 /* This parameter limits the number of branch elements that the
 156    scheduler will track anti-dependencies through without resetting
 157    the tracking mechanism.  Large functions with few calls or barriers
 158    can generate lists containing many 1000's of dependencies.  Generally
 159    the compiler either uses all available memory, or runs for far too long.  */
 160 DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
 161          "max-pending-list-length",
 162          "The maximum length of scheduling's pending operations list",
 163          32, 0, 0)
 164
 165 DEFPARAM(PARAM_LARGE_FUNCTION_INSNS,
 166          "large-function-insns",
 167          "The size of function body to be considered large",
 168          2700, 0, 0)
 169 DEFPARAM(PARAM_LARGE_FUNCTION_GROWTH,
 170          "large-function-growth",
 171          "Maximal growth due to inlining of large function (in percent)",
 172          100, 0, 0)
 173 DEFPARAM(PARAM_LARGE_UNIT_INSNS,
 174          "large-unit-insns",
 175          "The size of translation unit to be considered large",
 176          10000, 0, 0)
 177 DEFPARAM(PARAM_INLINE_UNIT_GROWTH,
 178          "inline-unit-growth",
 179          "How much can given compilation unit grow because of the inlining (in percent)",
 180          30, 0, 0)
 181 DEFPARAM(PARAM_IPCP_UNIT_GROWTH,
 182          "ipcp-unit-growth",
 183          "How much can given compilation unit grow because of the interprocedural constant propagation (in percent)",
 184          10, 0, 0)
 185 DEFPARAM(PARAM_EARLY_INLINING_INSNS,
 186          "early-inlining-insns",
 187          "Maximal estimated growth of function body caused by early inlining of single call",
 188          8, 0, 0)
 189 DEFPARAM(PARAM_LARGE_STACK_FRAME,
 190          "large-stack-frame",
 191          "The size of stack frame to be considered large",
 192          256, 0, 0)
 193 DEFPARAM(PARAM_STACK_FRAME_GROWTH,
 194          "large-stack-frame-growth",
 195          "Maximal stack frame growth due to inlining (in percent)",
 196          1000, 0, 0)
 197
 198 /* The GCSE optimization will be disabled if it would require
 199    significantly more memory than this value.  */
 200 DEFPARAM(PARAM_MAX_GCSE_MEMORY,
 201          "max-gcse-memory",
 202          "The maximum amount of memory to be allocated by GCSE",
 203          50 * 1024 * 1024, 0, 0)
 204
 205 /* This is the threshold ratio when to perform partial redundancy
 206    elimination after reload. We perform partial redundancy elimination
 207    when the following holds:
 208    (Redundant load execution count)
 209    ------------------------------- >= GCSE_AFTER_RELOAD_PARTIAL_FRACTION
 210    (Added loads execution count)                                          */
 211 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_PARTIAL_FRACTION,
 212         "gcse-after-reload-partial-fraction",
 213         "The threshold ratio for performing partial redundancy elimination after reload",
 214         3, 0, 0)
 215 /* This is the threshold ratio of the critical edges execution count compared to
 216    the redundant loads execution count that permits performing the load
 217    redundancy elimination in gcse after reload.  */
 218 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_CRITICAL_FRACTION,
 219         "gcse-after-reload-critical-fraction",
 220         "The threshold ratio of critical edges execution count that permit performing redundancy elimination after reload",
 221         10, 0, 0)
 222 /* This parameter limits the number of insns in a loop that will be unrolled,
 223    and by how much the loop is unrolled.
 224
 225    This limit should be at most half of the peeling limits:  loop unroller
 226    decides to not unroll loops that iterate fewer than 2*number of allowed
 227    unrollings and thus we would have loops that are neither peeled or unrolled
 228    otherwise.  */
 229 DEFPARAM(PARAM_MAX_UNROLLED_INSNS,
 230          "max-unrolled-insns",
 231          "The maximum number of instructions to consider to unroll in a loop",
 232          200, 0, 0)
 233 /* This parameter limits how many times the loop is unrolled depending
 234    on number of insns really executed in each iteration.  */
 235 DEFPARAM(PARAM_MAX_AVERAGE_UNROLLED_INSNS,
 236          "max-average-unrolled-insns",
 237          "The maximum number of instructions to consider to unroll in a loop on average",
 238          80, 0, 0)
 239 /* The maximum number of unrollings of a single loop.  */
 240 DEFPARAM(PARAM_MAX_UNROLL_TIMES,
 241         "max-unroll-times",
 242         "The maximum number of unrollings of a single loop",
 243         8, 0, 0)
 244 /* The maximum number of insns of a peeled loop.  */
 245 DEFPARAM(PARAM_MAX_PEELED_INSNS,
 246         "max-peeled-insns",
 247         "The maximum number of insns of a peeled loop",
 248         400, 0, 0)
 249 /* The maximum number of peelings of a single loop.  */
 250 DEFPARAM(PARAM_MAX_PEEL_TIMES,
 251         "max-peel-times",
 252         "The maximum number of peelings of a single loop",
 253         16, 0, 0)
 254 /* The maximum number of insns of a peeled loop.  */
 255 DEFPARAM(PARAM_MAX_COMPLETELY_PEELED_INSNS,
 256         "max-completely-peeled-insns",
 257         "The maximum number of insns of a completely peeled loop",
 258         400, 0, 0)
 259 /* The maximum number of peelings of a single loop that is peeled completely.  */
 260 DEFPARAM(PARAM_MAX_COMPLETELY_PEEL_TIMES,
 261         "max-completely-peel-times",
 262         "The maximum number of peelings of a single loop that is peeled completely",
 263         16, 0, 0)
 264 /* The maximum number of insns of a peeled loop that rolls only once.  */
 265 DEFPARAM(PARAM_MAX_ONCE_PEELED_INSNS,
 266         "max-once-peeled-insns",
 267         "The maximum number of insns of a peeled loop that rolls only once",
 268         400, 0, 0)
 269 /* The maximum depth of a loop nest we completely peel.  */
 270 DEFPARAM(PARAM_MAX_UNROLL_ITERATIONS,
 271          "max-completely-peel-loop-nest-depth",
 272          "The maximum depth of a loop nest we completely peel",
 273          8, 0, 0)
 274
 275 /* The maximum number of insns of an unswitched loop.  */
 276 DEFPARAM(PARAM_MAX_UNSWITCH_INSNS,
 277         "max-unswitch-insns",
 278         "The maximum number of insns of an unswitched loop",
 279         50, 0, 0)
 280 /* The maximum level of recursion in unswitch_single_loop.  */
 281 DEFPARAM(PARAM_MAX_UNSWITCH_LEVEL,
 282         "max-unswitch-level",
 283         "The maximum number of unswitchings in a single loop",
 284         3, 0, 0)
 285
 286 /* The maximum number of iterations of a loop the brute force algorithm
 287    for analysis of # of iterations of the loop tries to evaluate.  */
 288 DEFPARAM(PARAM_MAX_ITERATIONS_TO_TRACK,
 289         "max-iterations-to-track",
 290         "Bound on the number of iterations the brute force # of iterations analysis algorithm evaluates",
 291         1000, 0, 0)
 292 /* A cutoff to avoid costly computations of the number of iterations in
 293    the doloop transformation.  */
 294 DEFPARAM(PARAM_MAX_ITERATIONS_COMPUTATION_COST,
 295         "max-iterations-computation-cost",
 296         "Bound on the cost of an expression to compute the number of iterations",
 297         10, 0, 0)
 298
 299 /* This parameter is used to tune SMS MAX II calculations.  */
 300 DEFPARAM(PARAM_SMS_MAX_II_FACTOR,
 301          "sms-max-ii-factor",
 302          "A factor for tuning the upper bound that swing modulo scheduler uses for scheduling a loop",
 303          100, 0, 0)
 304 DEFPARAM(PARAM_SMS_DFA_HISTORY,
 305          "sms-dfa-history",
 306          "The number of cycles the swing modulo scheduler considers when checking conflicts using DFA",
 307          0, 0, 0)
 308 DEFPARAM(PARAM_SMS_LOOP_AVERAGE_COUNT_THRESHOLD,
 309          "sms-loop-average-count-threshold",
 310          "A threshold on the average loop count considered by the swing modulo scheduler",
 311          0, 0, 0)
 312
 313 DEFPARAM(HOT_BB_COUNT_FRACTION,
 314          "hot-bb-count-fraction",
 315          "Select fraction of the maximal count of repetitions of basic block in program given basic block needs to have to be considered hot",
 316          10000, 0, 0)
 317 DEFPARAM(HOT_BB_FREQUENCY_FRACTION,
 318          "hot-bb-frequency-fraction",
 319          "Select fraction of the maximal frequency of executions of basic block in function given basic block needs to have to be considered hot",
 320          1000, 0, 0)
 321
 322 DEFPARAM (PARAM_ALIGN_THRESHOLD,
 323           "align-threshold",
 324           "Select fraction of the maximal frequency of executions of basic block in function given basic block get alignment",
 325           100, 0, 0)
 326
 327 DEFPARAM (PARAM_ALIGN_LOOP_ITERATIONS,
 328           "align-loop-iterations",
 329           "Loops iterating at least selected number of iterations will get loop alignement.",
 330           4, 0, 0)
 331
 332 /* For guessed profiles, the loops having unknown number of iterations
 333    are predicted to iterate relatively few (10) times at average.
 334    For functions containing one loop with large known number of iterations
 335    and other loops having unbounded loops we would end up predicting all
 336    the other loops cold that is not usually the case.  So we need to artificially
 337    flatten the profile.
 338
 339    We need to cut the maximal predicted iterations to large enough iterations
 340    so the loop appears important, but safely within HOT_BB_COUNT_FRACTION
 341    range.  */
 342
 343 DEFPARAM(PARAM_MAX_PREDICTED_ITERATIONS,
 344          "max-predicted-iterations",
 345          "The maximum number of loop iterations we predict statically",
 346          100, 0, 0)
 347 DEFPARAM(TRACER_DYNAMIC_COVERAGE_FEEDBACK,
 348          "tracer-dynamic-coverage-feedback",
 349          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is available",
 350          95, 0, 100)
 351 DEFPARAM(TRACER_DYNAMIC_COVERAGE,
 352          "tracer-dynamic-coverage",
 353          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is not available",
 354          75, 0, 100)
 355 DEFPARAM(TRACER_MAX_CODE_GROWTH,
 356          "tracer-max-code-growth",
 357          "Maximal code growth caused by tail duplication (in percent)",
 358          100, 0, 0)
 359 DEFPARAM(TRACER_MIN_BRANCH_RATIO,
 360          "tracer-min-branch-ratio",
 361          "Stop reverse growth if the reverse probability of best edge is less than this threshold (in percent)",
 362          10, 0, 100)
 363 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK,
 364          "tracer-min-branch-probability-feedback",
 365          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is available",
 366          80, 0, 100)
 367 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY,
 368          "tracer-min-branch-probability",
 369          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is not available",
 370          50, 0, 100)
 371
 372 /* The maximum number of incoming edges to consider for crossjumping.  */
 373 DEFPARAM(PARAM_MAX_CROSSJUMP_EDGES,
 374          "max-crossjump-edges",
 375          "The maximum number of incoming edges to consider for crossjumping",
 376          100, 0, 0)
 377
 378 /* The minimum number of matching instructions to consider for crossjumping.  */
 379 DEFPARAM(PARAM_MIN_CROSSJUMP_INSNS,
 380      "min-crossjump-insns",
 381      "The minimum number of matching instructions to consider for crossjumping",
 382      5, 0, 0)
 383
 384 /* The maximum number expansion factor when copying basic blocks.  */
 385 DEFPARAM(PARAM_MAX_GROW_COPY_BB_INSNS,
 386      "max-grow-copy-bb-insns",
 387      "The maximum expansion factor when copying basic blocks",
 388      8, 0, 0)
 389
 390 /* The maximum number of insns to duplicate when unfactoring computed gotos.  */
 391 DEFPARAM(PARAM_MAX_GOTO_DUPLICATION_INSNS,
 392      "max-goto-duplication-insns",
 393      "The maximum number of insns to duplicate when unfactoring computed gotos",
 394      8, 0, 0)
 395
 396 /* The maximum length of path considered in cse.  */
 397 DEFPARAM(PARAM_MAX_CSE_PATH_LENGTH,
 398          "max-cse-path-length",
 399          "The maximum length of path considered in cse",
 400          10, 0, 0)
 401 DEFPARAM(PARAM_MAX_CSE_INSNS,
 402          "max-cse-insns",
 403          "The maximum instructions CSE process before flushing",
 404          1000, 0, 0)
 405
 406 /* The cost of expression in loop invariant motion that is considered
 407    expensive.  */
 408 DEFPARAM(PARAM_LIM_EXPENSIVE,
 409          "lim-expensive",
 410          "The minimum cost of an expensive expression in the loop invariant motion",
 411          20, 0, 0)
 412
 413 /* Bound on number of candidates for induction variables below that
 414    all candidates are considered for each use in induction variable
 415    optimizations.  */
 416
 417 DEFPARAM(PARAM_IV_CONSIDER_ALL_CANDIDATES_BOUND,
 418          "iv-consider-all-candidates-bound",
 419          "Bound on number of candidates below that all candidates are considered in iv optimizations",
 420          30, 0, 0)
 421
 422 /* The induction variable optimizations give up on loops that contain more
 423    induction variable uses.  */
 424
 425 DEFPARAM(PARAM_IV_MAX_CONSIDERED_USES,
 426          "iv-max-considered-uses",
 427          "Bound on number of iv uses in loop optimized in iv optimizations",
 428          250, 0, 0)
 429
 430 /* If there are at most this number of ivs in the set, try removing unnecessary
 431    ivs from the set always.  */
 432
 433 DEFPARAM(PARAM_IV_ALWAYS_PRUNE_CAND_SET_BOUND,
 434          "iv-always-prune-cand-set-bound",
 435          "If number of candidates in the set is smaller, we always try to remove unused ivs during its optimization",
 436          10, 0, 0)
 437
 438 DEFPARAM(PARAM_SCEV_MAX_EXPR_SIZE,
 439          "scev-max-expr-size",
 440          "Bound on size of expressions used in the scalar evolutions analyzer",
 441          20, 0, 0)
 442
 443 DEFPARAM(PARAM_OMEGA_MAX_VARS,
 444          "omega-max-vars",
 445          "Bound on the number of variables in Omega constraint systems",
 446          128, 0, 0)
 447
 448 DEFPARAM(PARAM_OMEGA_MAX_GEQS,
 449          "omega-max-geqs",
 450          "Bound on the number of inequalities in Omega constraint systems",
 451          256, 0, 0)
 452
 453 DEFPARAM(PARAM_OMEGA_MAX_EQS,
 454          "omega-max-eqs",
 455          "Bound on the number of equalities in Omega constraint systems",
 456          128, 0, 0)
 457
 458 DEFPARAM(PARAM_OMEGA_MAX_WILD_CARDS,
 459          "omega-max-wild-cards",
 460          "Bound on the number of wild cards in Omega constraint systems",
 461          18, 0, 0)
 462
 463 DEFPARAM(PARAM_OMEGA_HASH_TABLE_SIZE,
 464          "omega-hash-table-size",
 465          "Bound on the size of the hash table in Omega constraint systems",
 466          550, 0, 0)
 467
 468 DEFPARAM(PARAM_OMEGA_MAX_KEYS,
 469          "omega-max-keys",
 470          "Bound on the number of keys in Omega constraint systems",
 471          500, 0, 0)
 472
 473 DEFPARAM(PARAM_OMEGA_ELIMINATE_REDUNDANT_CONSTRAINTS,
 474          "omega-eliminate-redundant-constraints",
 475          "When set to 1, use expensive methods to eliminate all redundant constraints",
 476          0, 0, 1)
 477
 478 DEFPARAM(PARAM_VECT_MAX_VERSION_FOR_ALIGNMENT_CHECKS,
 479          "vect-max-version-for-alignment-checks",
 480          "Bound on number of runtime checks inserted by the vectorizer's loop versioning for alignment check",
 481          6, 0, 0)
 482
 483 DEFPARAM(PARAM_VECT_MAX_VERSION_FOR_ALIAS_CHECKS,
 484          "vect-max-version-for-alias-checks",
 485          "Bound on number of runtime checks inserted by the vectorizer's loop versioning for alias check",
 486          10, 0, 0)
 487
 488 DEFPARAM(PARAM_MAX_CSELIB_MEMORY_LOCATIONS,
 489          "max-cselib-memory-locations",
 490          "The maximum memory locations recorded by cselib",
 491          500, 0, 0)
 492
 493 #ifdef ENABLE_GC_ALWAYS_COLLECT
 494 # define GGC_MIN_EXPAND_DEFAULT 0
 495 # define GGC_MIN_HEAPSIZE_DEFAULT 0
 496 #else
 497 # define GGC_MIN_EXPAND_DEFAULT 30
 498 # define GGC_MIN_HEAPSIZE_DEFAULT 4096
 499 #endif
 500
 501 DEFPARAM(GGC_MIN_EXPAND,
 502          "ggc-min-expand",
 503          "Minimum heap expansion to trigger garbage collection, as a percentage of the total size of the heap",
 504          GGC_MIN_EXPAND_DEFAULT, 0, 0)
 505
 506 DEFPARAM(GGC_MIN_HEAPSIZE,
 507          "ggc-min-heapsize",
 508          "Minimum heap size before we start collecting garbage, in kilobytes",
 509          GGC_MIN_HEAPSIZE_DEFAULT, 0, 0)
 510
 511 #undef GGC_MIN_EXPAND_DEFAULT
 512 #undef GGC_MIN_HEAPSIZE_DEFAULT
 513
 514 DEFPARAM(PARAM_MAX_RELOAD_SEARCH_INSNS,
 515          "max-reload-search-insns",
 516          "The maximum number of instructions to search backward when looking for equivalent reload",
 517          100, 0, 0)
 518
 519 DEFPARAM(PARAM_MAX_SCHED_REGION_BLOCKS,
 520          "max-sched-region-blocks",
 521          "The maximum number of blocks in a region to be considered for interblock scheduling",
 522          10, 0, 0)
 523
 524 DEFPARAM(PARAM_MAX_SCHED_REGION_INSNS,
 525          "max-sched-region-insns",
 526          "The maximum number of insns in a region to be considered for interblock scheduling",
 527          100, 0, 0)
 528
 529 DEFPARAM(PARAM_MAX_PIPELINE_REGION_BLOCKS,
 530          "max-pipeline-region-blocks",
 531          "The maximum number of blocks in a region to be considered for interblock scheduling",
 532          15, 0, 0)
 533
 534 DEFPARAM(PARAM_MAX_PIPELINE_REGION_INSNS,
 535          "max-pipeline-region-insns",
 536          "The maximum number of insns in a region to be considered for interblock scheduling",
 537          200, 0, 0)
 538
 539 DEFPARAM(PARAM_MIN_SPEC_PROB,
 540          "min-spec-prob",
 541          "The minimum probability of reaching a source block for interblock speculative scheduling",
 542          40, 0, 0)
 543
 544 DEFPARAM(PARAM_MAX_SCHED_EXTEND_REGIONS_ITERS,
 545          "max-sched-extend-regions-iters",
 546          "The maximum number of iterations through CFG to extend regions",
 547          0, 0, 0)
 548
 549 DEFPARAM(PARAM_MAX_SCHED_INSN_CONFLICT_DELAY,
 550          "max-sched-insn-conflict-delay",
 551          "The maximum conflict delay for an insn to be considered for speculative motion",
 552          3, 1, 10)
 553
 554 DEFPARAM(PARAM_SCHED_SPEC_PROB_CUTOFF,
 555          "sched-spec-prob-cutoff",
 556          "The minimal probability of speculation success (in percents), so that speculative insn will be scheduled.",
 557          40, 0, 100)
 558
 559 DEFPARAM(PARAM_SELSCHED_MAX_LOOKAHEAD,
 560          "selsched-max-lookahead",
 561          "The maximum size of the lookahead window of selective scheduling",
 562          50, 0, 0)
 563
 564 DEFPARAM(PARAM_SELSCHED_MAX_SCHED_TIMES,
 565          "selsched-max-sched-times",
 566          "Maximum number of times that an insn could be scheduled",
 567          2, 0, 0)
 568
 569 DEFPARAM(PARAM_SELSCHED_INSNS_TO_RENAME,
 570          "selsched-insns-to-rename",
 571          "Maximum number of instructions in the ready list that are considered eligible for renaming",
 572          2, 0, 0)
 573
 574 DEFPARAM (PARAM_SCHED_MEM_TRUE_DEP_COST,
 575           "sched-mem-true-dep-cost",
 576           "Minimal distance between possibly conflicting store and load",
 577           1, 0, 0)
 578
 579 DEFPARAM(PARAM_MAX_LAST_VALUE_RTL,
 580          "max-last-value-rtl",
 581          "The maximum number of RTL nodes that can be recorded as combiner's last value",
 582          10000, 0, 0)
 583
 584 /* INTEGER_CST nodes are shared for values [{-1,0} .. N) for
 585    {signed,unsigned} integral types.  This determines N.
 586    Experimentation shows 256 to be a good value.  */
 587 DEFPARAM (PARAM_INTEGER_SHARE_LIMIT,
 588           "integer-share-limit",
 589           "The upper bound for sharing integer constants",
 590           256, 2, 2)
 591
 592 /* Incremental SSA updates for virtual operands may be very slow if
 593    there is a large number of mappings to process.  In those cases, it
 594    is faster to rewrite the virtual symbols from scratch as if they
 595    had been recently introduced.  This heuristic cannot be applied to
 596    SSA mappings for real SSA names, only symbols kept in FUD chains.
 597
 598    PARAM_MIN_VIRTUAL_MAPPINGS specifies the minimum number of virtual
 599    mappings that should be registered to trigger the heuristic.
 600
 601    PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO specifies the ratio between
 602    mappings and symbols.  If the number of virtual mappings is
 603    PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO bigger than the number of
 604    virtual symbols to be updated, then the updater switches to a full
 605    update for those symbols.  */
 606 DEFPARAM (PARAM_MIN_VIRTUAL_MAPPINGS,
 607           "min-virtual-mappings",
 608           "Minimum number of virtual mappings to consider switching to full virtual renames",
 609           100, 0, 0)
 610
 611 DEFPARAM (PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO,
 612           "virtual-mappings-ratio",
 613           "Ratio between virtual mappings and virtual symbols to do full virtual renames",
 614           3, 0, 0)
 615
 616 DEFPARAM (PARAM_SSP_BUFFER_SIZE,
 617           "ssp-buffer-size",
 618           "The lower bound for a buffer to be considered for stack smashing protection",
 619           8, 1, 0)
 620
 621 /* When we thread through a block we have to make copies of the
 622    statements within the block.  Clearly for large blocks the code
 623    duplication is bad.
 624
 625    PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS specifies the maximum number
 626    of statements and PHI nodes allowed in a block which is going to
 627    be duplicated for thread jumping purposes.
 628
 629    Some simple analysis showed that more than 99% of the jump
 630    threading opportunities are for blocks with less than 15
 631    statements.  So we can get the benefits of jump threading
 632    without excessive code bloat for pathological cases with the
 633    throttle set at 15 statements.  */
 634 DEFPARAM (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS,
 635           "max-jump-thread-duplication-stmts",
 636           "Maximum number of statements allowed in a block that needs to be duplicated when threading jumps",
 637           15, 0, 0)
 638
 639 /* This is the maximum number of fields a variable may have before the pointer analysis machinery
 640    will stop trying to treat it in a field-sensitive manner.
 641    There are programs out there with thousands of fields per structure, and handling them
 642    field-sensitively is not worth the cost.  */
 643 DEFPARAM (PARAM_MAX_FIELDS_FOR_FIELD_SENSITIVE,
 644           "max-fields-for-field-sensitive",
 645           "Maximum number of fields in a structure before pointer analysis treats the structure as a single variable",
 646           0, 0, 0)
 647
 648 DEFPARAM(PARAM_MAX_SCHED_READY_INSNS,
 649          "max-sched-ready-insns",
 650          "The maximum number of instructions ready to be issued to be considered by the scheduler during the first scheduling pass",
 651          100, 0, 0)
 652
 653 /* Prefetching and cache-optimizations related parameters.  Default values are
 654    usually set by machine description.  */
 655
 656 /* The number of insns executed before prefetch is completed.  */
 657
 658 DEFPARAM (PARAM_PREFETCH_LATENCY,
 659          "prefetch-latency",
 660          "The number of insns executed before prefetch is completed",
 661          200, 0, 0)
 662
 663 /* The number of prefetches that can run at the same time.  */
 664
 665 DEFPARAM (PARAM_SIMULTANEOUS_PREFETCHES,
 666           "simultaneous-prefetches",
 667           "The number of prefetches that can run at the same time",
 668           3, 0, 0)
 669
 670 /* The size of L1 cache in kB.  */
 671
 672 DEFPARAM (PARAM_L1_CACHE_SIZE,
 673           "l1-cache-size",
 674           "The size of L1 cache",
 675           64, 0, 0)
 676
 677 /* The size of L1 cache line in bytes.  */
 678
 679 DEFPARAM (PARAM_L1_CACHE_LINE_SIZE,
 680           "l1-cache-line-size",
 681           "The size of L1 cache line",
 682           32, 0, 0)
 683
 684 /* The size of L2 cache in kB.  */
 685
 686 DEFPARAM (PARAM_L2_CACHE_SIZE,
 687           "l2-cache-size",
 688           "The size of L2 cache",
 689           512, 0, 0)
 690
 691 /* Whether we should use canonical types rather than deep "structural"
 692    type checking.  Setting this value to 1 (the default) improves
 693    compilation performance in the C++ and Objective-C++ front end;
 694    this value should only be set to zero to work around bugs in the
 695    canonical type system by disabling it.  */
 696
 697 DEFPARAM (PARAM_USE_CANONICAL_TYPES,
 698           "use-canonical-types",
 699           "Whether to use canonical types",
 700           1, 0, 1)
 701
 702 DEFPARAM (PARAM_MAX_PARTIAL_ANTIC_LENGTH,
 703           "max-partial-antic-length",
 704           "Maximum length of partial antic set when performing tree pre optimization",
 705           100, 0, 0)
 706
 707 /* The following is used as a stop-gap limit for cases where really huge
 708    SCCs blow up memory and compile-time use too much.  If we hit this limit,
 709    SCCVN and such FRE and PRE will be not done at all for the current
 710    function.  */
 711
 712 DEFPARAM (PARAM_SCCVN_MAX_SCC_SIZE,
 713           "sccvn-max-scc-size",
 714           "Maximum size of a SCC before SCCVN stops processing a function",
 715           10000, 10, 0)
 716
 717 DEFPARAM (PARAM_IRA_MAX_LOOPS_NUM,
 718           "ira-max-loops-num",
 719           "Max loops number for regional RA",
 720           100, 0, 0)
 721
 722 DEFPARAM (PARAM_IRA_MAX_CONFLICT_TABLE_SIZE,
 723           "ira-max-conflict-table-size",
 724           "Max size of conflict table in MB",
 725           1000, 0, 0)
 726
 727 DEFPARAM (PARAM_IRA_LOOP_RESERVED_REGS,
 728           "ira-loop-reserved-regs",
 729           "The number of registers in each class kept unused by loop invariant motion",
 730           2, 0, 0)
 731
 732 /* Switch initialization conversion will refuse to create arrays that are
 733    bigger than this parameter times the number of switch branches.  */
 734
 735 DEFPARAM (PARAM_SWITCH_CONVERSION_BRANCH_RATIO,
 736           "switch-conversion-max-branch-ratio",
 737           "The maximum ratio between array size and switch branches for "
 738           "a switch conversion to take place",
 739           8, 1, 0)
 740
 741 /* Size of tiles when doing loop blocking.  */
 742
 743 DEFPARAM (PARAM_LOOP_BLOCK_TILE_SIZE,
 744           "loop-block-tile-size",
 745           "size of tiles for loop blocking",
 746           51, 0, 0)
 747
 748 /* Maximal number of parameters that we allow in a SCoP.  */
 749
 750 DEFPARAM (PARAM_GRAPHITE_MAX_NB_SCOP_PARAMS,
 751           "graphite-max-nb-scop-params",
 752           "maximum number of parameters in a SCoP",
 753           10, 0, 0)
 754
 755 /* Maximal number of basic blocks in the functions analyzed by Graphite.  */
 756
 757 DEFPARAM (PARAM_GRAPHITE_MAX_BBS_PER_FUNCTION,
 758           "graphite-max-bbs-per-function",
 759           "maximum number of basic blocks per function to be analyzed by Graphite",
 760           100, 0, 0)
 761
 762 /* Avoid doing loop invariant motion on very large loops.  */
 763
 764 DEFPARAM (PARAM_LOOP_INVARIANT_MAX_BBS_IN_LOOP,
 765           "loop-invariant-max-bbs-in-loop",
 766           "Max basic blocks number in loop for loop invariant motion",
 767           10000, 0, 0)
 768
 769 /* Avoid SLP vectorization of large basic blocks.  */
 770 DEFPARAM (PARAM_SLP_MAX_INSNS_IN_BB,
 771           "slp-max-insns-in-bb",
 772           "Maximum number of instructions in basic block to be considered for SLP vectorization",
 773           1000, 0, 0)
 774
 775 DEFPARAM (PARAM_MIN_INSN_TO_PREFETCH_RATIO,
 776           "min-insn-to-prefetch-ratio",
 777           "Min. ratio of insns to prefetches to enable prefetching for "
 778           "a loop with an unknown trip count",
 779           10, 0, 0)
 780
 781 DEFPARAM (PARAM_PREFETCH_MIN_INSN_TO_MEM_RATIO,
 782           "prefetch-min-insn-to-mem-ratio",
 783           "Min. ratio of insns to mem ops to enable prefetching in a loop",
 784           3, 0, 0)
 785
 786 /* Set maximum hash table size for var tracking.  */
 787
 788 DEFPARAM (PARAM_MAX_VARTRACK_SIZE,
 789           "max-vartrack-size",
 790           "Max. size of var tracking hash tables",
 791           50000000, 0, 0)
 792
 793 /* Set minimum insn uid for non-debug insns.  */
 794
 795 DEFPARAM (PARAM_MIN_NONDEBUG_INSN_UID,
 796           "min-nondebug-insn-uid",
 797           "The minimum UID to be used for a nondebug insn",
 798           0, 1, 0)
 799
 800 DEFPARAM (PARAM_IPA_SRA_PTR_GROWTH_FACTOR,
 801           "ipa-sra-ptr-growth-factor",
 802           "Maximum allowed growth of size of new parameters ipa-sra replaces "
 803           "a pointer to an aggregate with",
 804           2, 0, 0)
 805
 806 /*
 807 Local variables:
 808 mode:c
 809 End:
 810 */