gcc/params.def

   1 /* params.def - Run-time parameters.
   2    Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
   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 40.  */
  82 DEFPARAM (PARAM_MAX_INLINE_INSNS_AUTO,
  83           "max-inline-insns-auto",
  84           "The maximum number of instructions when automatically inlining",
  85           40, 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 on probability of entry BB.  */
 121 DEFPARAM (PARAM_PARTIAL_INLINING_ENTRY_PROBABILITY,
 122           "partial-inlining-entry-probability",
 123           "Maximum probability of the entry BB of split region (in percent relative to entry BB of the function) to make partial inlining happen",
 124           70, 0, 0)
 125
 126 /* Limit the number of expansions created by the variable expansion
 127    optimization to avoid register pressure.  */
 128 DEFPARAM (PARAM_MAX_VARIABLE_EXPANSIONS,
 129           "max-variable-expansions-in-unroller",
 130           "If -fvariable-expansion-in-unroller is used, the maximum number of times that an individual variable will be expanded during loop unrolling",
 131           1, 0, 0)
 132
 133 /* Limit loop autovectorization to loops with large enough iteration count.  */
 134 DEFPARAM (PARAM_MIN_VECT_LOOP_BOUND,
 135           "min-vect-loop-bound",
 136           "If -ftree-vectorize is used, the minimal loop bound of a loop to be considered for vectorization",
 137           1, 1, 0)
 138
 139 /* The maximum number of instructions to consider when looking for an
 140    instruction to fill a delay slot.  If more than this arbitrary
 141    number of instructions is searched, the time savings from filling
 142    the delay slot will be minimal so stop searching.  Increasing
 143    values mean more aggressive optimization, making the compile time
 144    increase with probably small improvement in executable run time.  */
 145 DEFPARAM (PARAM_MAX_DELAY_SLOT_INSN_SEARCH,
 146           "max-delay-slot-insn-search",
 147           "The maximum number of instructions to consider to fill a delay slot",
 148           100, 0, 0)
 149
 150 /* When trying to fill delay slots, the maximum number of instructions
 151    to consider when searching for a block with valid live register
 152    information.  Increasing this arbitrarily chosen value means more
 153    aggressive optimization, increasing the compile time.  This
 154    parameter should be removed when the delay slot code is rewritten
 155    to maintain the control-flow graph.  */
 156 DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
 157          "max-delay-slot-live-search",
 158          "The maximum number of instructions to consider to find accurate live register information",
 159          333, 0, 0)
 160
 161 /* This parameter limits the number of branch elements that the
 162    scheduler will track anti-dependencies through without resetting
 163    the tracking mechanism.  Large functions with few calls or barriers
 164    can generate lists containing many 1000's of dependencies.  Generally
 165    the compiler either uses all available memory, or runs for far too long.  */
 166 DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
 167          "max-pending-list-length",
 168          "The maximum length of scheduling's pending operations list",
 169          32, 0, 0)
 170
 171 DEFPARAM(PARAM_LARGE_FUNCTION_INSNS,
 172          "large-function-insns",
 173          "The size of function body to be considered large",
 174          2700, 0, 0)
 175 DEFPARAM(PARAM_LARGE_FUNCTION_GROWTH,
 176          "large-function-growth",
 177          "Maximal growth due to inlining of large function (in percent)",
 178          100, 0, 0)
 179 DEFPARAM(PARAM_LARGE_UNIT_INSNS,
 180          "large-unit-insns",
 181          "The size of translation unit to be considered large",
 182          10000, 0, 0)
 183 DEFPARAM(PARAM_INLINE_UNIT_GROWTH,
 184          "inline-unit-growth",
 185          "How much can given compilation unit grow because of the inlining (in percent)",
 186          30, 0, 0)
 187 DEFPARAM(PARAM_IPCP_UNIT_GROWTH,
 188          "ipcp-unit-growth",
 189          "How much can given compilation unit grow because of the interprocedural constant propagation (in percent)",
 190          10, 0, 0)
 191 DEFPARAM(PARAM_EARLY_INLINING_INSNS,
 192          "early-inlining-insns",
 193          "Maximal estimated growth of function body caused by early inlining of single call",
 194          8, 0, 0)
 195 DEFPARAM(PARAM_LARGE_STACK_FRAME,
 196          "large-stack-frame",
 197          "The size of stack frame to be considered large",
 198          256, 0, 0)
 199 DEFPARAM(PARAM_STACK_FRAME_GROWTH,
 200          "large-stack-frame-growth",
 201          "Maximal stack frame growth due to inlining (in percent)",
 202          1000, 0, 0)
 203
 204 /* The GCSE optimization will be disabled if it would require
 205    significantly more memory than this value.  */
 206 DEFPARAM(PARAM_MAX_GCSE_MEMORY,
 207          "max-gcse-memory",
 208          "The maximum amount of memory to be allocated by GCSE",
 209          50 * 1024 * 1024, 0, 0)
 210
 211 /* This is the threshold ratio when to perform partial redundancy
 212    elimination after reload. We perform partial redundancy elimination
 213    when the following holds:
 214    (Redundant load execution count)
 215    ------------------------------- >= GCSE_AFTER_RELOAD_PARTIAL_FRACTION
 216    (Added loads execution count)                                          */
 217 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_PARTIAL_FRACTION,
 218         "gcse-after-reload-partial-fraction",
 219         "The threshold ratio for performing partial redundancy elimination after reload",
 220         3, 0, 0)
 221 /* This is the threshold ratio of the critical edges execution count compared to
 222    the redundant loads execution count that permits performing the load
 223    redundancy elimination in gcse after reload.  */
 224 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_CRITICAL_FRACTION,
 225         "gcse-after-reload-critical-fraction",
 226         "The threshold ratio of critical edges execution count that permit performing redundancy elimination after reload",
 227         10, 0, 0)
 228 /* This parameter limits the number of insns in a loop that will be unrolled,
 229    and by how much the loop is unrolled.
 230
 231    This limit should be at most half of the peeling limits:  loop unroller
 232    decides to not unroll loops that iterate fewer than 2*number of allowed
 233    unrollings and thus we would have loops that are neither peeled or unrolled
 234    otherwise.  */
 235 DEFPARAM(PARAM_MAX_UNROLLED_INSNS,
 236          "max-unrolled-insns",
 237          "The maximum number of instructions to consider to unroll in a loop",
 238          200, 0, 0)
 239 /* This parameter limits how many times the loop is unrolled depending
 240    on number of insns really executed in each iteration.  */
 241 DEFPARAM(PARAM_MAX_AVERAGE_UNROLLED_INSNS,
 242          "max-average-unrolled-insns",
 243          "The maximum number of instructions to consider to unroll in a loop on average",
 244          80, 0, 0)
 245 /* The maximum number of unrollings of a single loop.  */
 246 DEFPARAM(PARAM_MAX_UNROLL_TIMES,
 247         "max-unroll-times",
 248         "The maximum number of unrollings of a single loop",
 249         8, 0, 0)
 250 /* The maximum number of insns of a peeled loop.  */
 251 DEFPARAM(PARAM_MAX_PEELED_INSNS,
 252         "max-peeled-insns",
 253         "The maximum number of insns of a peeled loop",
 254         400, 0, 0)
 255 /* The maximum number of peelings of a single loop.  */
 256 DEFPARAM(PARAM_MAX_PEEL_TIMES,
 257         "max-peel-times",
 258         "The maximum number of peelings of a single loop",
 259         16, 0, 0)
 260 /* The maximum number of insns of a peeled loop.  */
 261 DEFPARAM(PARAM_MAX_COMPLETELY_PEELED_INSNS,
 262         "max-completely-peeled-insns",
 263         "The maximum number of insns of a completely peeled loop",
 264         400, 0, 0)
 265 /* The maximum number of peelings of a single loop that is peeled completely.  */
 266 DEFPARAM(PARAM_MAX_COMPLETELY_PEEL_TIMES,
 267         "max-completely-peel-times",
 268         "The maximum number of peelings of a single loop that is peeled completely",
 269         16, 0, 0)
 270 /* The maximum number of insns of a peeled loop that rolls only once.  */
 271 DEFPARAM(PARAM_MAX_ONCE_PEELED_INSNS,
 272         "max-once-peeled-insns",
 273         "The maximum number of insns of a peeled loop that rolls only once",
 274         400, 0, 0)
 275 /* The maximum depth of a loop nest we completely peel.  */
 276 DEFPARAM(PARAM_MAX_UNROLL_ITERATIONS,
 277          "max-completely-peel-loop-nest-depth",
 278          "The maximum depth of a loop nest we completely peel",
 279          8, 0, 0)
 280
 281 /* The maximum number of insns of an unswitched loop.  */
 282 DEFPARAM(PARAM_MAX_UNSWITCH_INSNS,
 283         "max-unswitch-insns",
 284         "The maximum number of insns of an unswitched loop",
 285         50, 0, 0)
 286 /* The maximum level of recursion in unswitch_single_loop.  */
 287 DEFPARAM(PARAM_MAX_UNSWITCH_LEVEL,
 288         "max-unswitch-level",
 289         "The maximum number of unswitchings in a single loop",
 290         3, 0, 0)
 291
 292 /* The maximum number of iterations of a loop the brute force algorithm
 293    for analysis of # of iterations of the loop tries to evaluate.  */
 294 DEFPARAM(PARAM_MAX_ITERATIONS_TO_TRACK,
 295         "max-iterations-to-track",
 296         "Bound on the number of iterations the brute force # of iterations analysis algorithm evaluates",
 297         1000, 0, 0)
 298 /* A cutoff to avoid costly computations of the number of iterations in
 299    the doloop transformation.  */
 300 DEFPARAM(PARAM_MAX_ITERATIONS_COMPUTATION_COST,
 301         "max-iterations-computation-cost",
 302         "Bound on the cost of an expression to compute the number of iterations",
 303         10, 0, 0)
 304
 305 /* This parameter is used to tune SMS MAX II calculations.  */
 306 DEFPARAM(PARAM_SMS_MAX_II_FACTOR,
 307          "sms-max-ii-factor",
 308          "A factor for tuning the upper bound that swing modulo scheduler uses for scheduling a loop",
 309          100, 0, 0)
 310 DEFPARAM(PARAM_SMS_DFA_HISTORY,
 311          "sms-dfa-history",
 312          "The number of cycles the swing modulo scheduler considers when checking conflicts using DFA",
 313          0, 0, 0)
 314 DEFPARAM(PARAM_SMS_LOOP_AVERAGE_COUNT_THRESHOLD,
 315          "sms-loop-average-count-threshold",
 316          "A threshold on the average loop count considered by the swing modulo scheduler",
 317          0, 0, 0)
 318
 319 DEFPARAM(HOT_BB_COUNT_FRACTION,
 320          "hot-bb-count-fraction",
 321          "Select fraction of the maximal count of repetitions of basic block in program given basic block needs to have to be considered hot",
 322          10000, 0, 0)
 323 DEFPARAM(HOT_BB_FREQUENCY_FRACTION,
 324          "hot-bb-frequency-fraction",
 325          "Select fraction of the maximal frequency of executions of basic block in function given basic block needs to have to be considered hot",
 326          1000, 0, 0)
 327
 328 DEFPARAM (PARAM_ALIGN_THRESHOLD,
 329           "align-threshold",
 330           "Select fraction of the maximal frequency of executions of basic block in function given basic block get alignment",
 331           100, 0, 0)
 332
 333 DEFPARAM (PARAM_ALIGN_LOOP_ITERATIONS,
 334           "align-loop-iterations",
 335           "Loops iterating at least selected number of iterations will get loop alignement.",
 336           4, 0, 0)
 337
 338 /* For guessed profiles, the loops having unknown number of iterations
 339    are predicted to iterate relatively few (10) times at average.
 340    For functions containing one loop with large known number of iterations
 341    and other loops having unbounded loops we would end up predicting all
 342    the other loops cold that is not usually the case.  So we need to artificially
 343    flatten the profile.
 344
 345    We need to cut the maximal predicted iterations to large enough iterations
 346    so the loop appears important, but safely within HOT_BB_COUNT_FRACTION
 347    range.  */
 348
 349 DEFPARAM(PARAM_MAX_PREDICTED_ITERATIONS,
 350          "max-predicted-iterations",
 351          "The maximum number of loop iterations we predict statically",
 352          100, 0, 0)
 353 DEFPARAM(TRACER_DYNAMIC_COVERAGE_FEEDBACK,
 354          "tracer-dynamic-coverage-feedback",
 355          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is available",
 356          95, 0, 100)
 357 DEFPARAM(TRACER_DYNAMIC_COVERAGE,
 358          "tracer-dynamic-coverage",
 359          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is not available",
 360          75, 0, 100)
 361 DEFPARAM(TRACER_MAX_CODE_GROWTH,
 362          "tracer-max-code-growth",
 363          "Maximal code growth caused by tail duplication (in percent)",
 364          100, 0, 0)
 365 DEFPARAM(TRACER_MIN_BRANCH_RATIO,
 366          "tracer-min-branch-ratio",
 367          "Stop reverse growth if the reverse probability of best edge is less than this threshold (in percent)",
 368          10, 0, 100)
 369 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK,
 370          "tracer-min-branch-probability-feedback",
 371          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is available",
 372          80, 0, 100)
 373 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY,
 374          "tracer-min-branch-probability",
 375          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is not available",
 376          50, 0, 100)
 377
 378 /* The maximum number of incoming edges to consider for crossjumping.  */
 379 DEFPARAM(PARAM_MAX_CROSSJUMP_EDGES,
 380          "max-crossjump-edges",
 381          "The maximum number of incoming edges to consider for crossjumping",
 382          100, 0, 0)
 383
 384 /* The minimum number of matching instructions to consider for crossjumping.  */
 385 DEFPARAM(PARAM_MIN_CROSSJUMP_INSNS,
 386      "min-crossjump-insns",
 387      "The minimum number of matching instructions to consider for crossjumping",
 388      5, 0, 0)
 389
 390 /* The maximum number expansion factor when copying basic blocks.  */
 391 DEFPARAM(PARAM_MAX_GROW_COPY_BB_INSNS,
 392      "max-grow-copy-bb-insns",
 393      "The maximum expansion factor when copying basic blocks",
 394      8, 0, 0)
 395
 396 /* The maximum number of insns to duplicate when unfactoring computed gotos.  */
 397 DEFPARAM(PARAM_MAX_GOTO_DUPLICATION_INSNS,
 398      "max-goto-duplication-insns",
 399      "The maximum number of insns to duplicate when unfactoring computed gotos",
 400      8, 0, 0)
 401
 402 /* The maximum length of path considered in cse.  */
 403 DEFPARAM(PARAM_MAX_CSE_PATH_LENGTH,
 404          "max-cse-path-length",
 405          "The maximum length of path considered in cse",
 406          10, 0, 0)
 407 DEFPARAM(PARAM_MAX_CSE_INSNS,
 408          "max-cse-insns",
 409          "The maximum instructions CSE process before flushing",
 410          1000, 0, 0)
 411
 412 /* The cost of expression in loop invariant motion that is considered
 413    expensive.  */
 414 DEFPARAM(PARAM_LIM_EXPENSIVE,
 415          "lim-expensive",
 416          "The minimum cost of an expensive expression in the loop invariant motion",
 417          20, 0, 0)
 418
 419 /* Bound on number of candidates for induction variables below that
 420    all candidates are considered for each use in induction variable
 421    optimizations.  */
 422
 423 DEFPARAM(PARAM_IV_CONSIDER_ALL_CANDIDATES_BOUND,
 424          "iv-consider-all-candidates-bound",
 425          "Bound on number of candidates below that all candidates are considered in iv optimizations",
 426          30, 0, 0)
 427
 428 /* The induction variable optimizations give up on loops that contain more
 429    induction variable uses.  */
 430
 431 DEFPARAM(PARAM_IV_MAX_CONSIDERED_USES,
 432          "iv-max-considered-uses",
 433          "Bound on number of iv uses in loop optimized in iv optimizations",
 434          250, 0, 0)
 435
 436 /* If there are at most this number of ivs in the set, try removing unnecessary
 437    ivs from the set always.  */
 438
 439 DEFPARAM(PARAM_IV_ALWAYS_PRUNE_CAND_SET_BOUND,
 440          "iv-always-prune-cand-set-bound",
 441          "If number of candidates in the set is smaller, we always try to remove unused ivs during its optimization",
 442          10, 0, 0)
 443
 444 DEFPARAM(PARAM_SCEV_MAX_EXPR_SIZE,
 445          "scev-max-expr-size",
 446          "Bound on size of expressions used in the scalar evolutions analyzer",
 447          20, 0, 0)
 448
 449 DEFPARAM(PARAM_OMEGA_MAX_VARS,
 450          "omega-max-vars",
 451          "Bound on the number of variables in Omega constraint systems",
 452          128, 0, 0)
 453
 454 DEFPARAM(PARAM_OMEGA_MAX_GEQS,
 455          "omega-max-geqs",
 456          "Bound on the number of inequalities in Omega constraint systems",
 457          256, 0, 0)
 458
 459 DEFPARAM(PARAM_OMEGA_MAX_EQS,
 460          "omega-max-eqs",
 461          "Bound on the number of equalities in Omega constraint systems",
 462          128, 0, 0)
 463
 464 DEFPARAM(PARAM_OMEGA_MAX_WILD_CARDS,
 465          "omega-max-wild-cards",
 466          "Bound on the number of wild cards in Omega constraint systems",
 467          18, 0, 0)
 468
 469 DEFPARAM(PARAM_OMEGA_HASH_TABLE_SIZE,
 470          "omega-hash-table-size",
 471          "Bound on the size of the hash table in Omega constraint systems",
 472          550, 0, 0)
 473
 474 DEFPARAM(PARAM_OMEGA_MAX_KEYS,
 475          "omega-max-keys",
 476          "Bound on the number of keys in Omega constraint systems",
 477          500, 0, 0)
 478
 479 DEFPARAM(PARAM_OMEGA_ELIMINATE_REDUNDANT_CONSTRAINTS,
 480          "omega-eliminate-redundant-constraints",
 481          "When set to 1, use expensive methods to eliminate all redundant constraints",
 482          0, 0, 1)
 483
 484 DEFPARAM(PARAM_VECT_MAX_VERSION_FOR_ALIGNMENT_CHECKS,
 485          "vect-max-version-for-alignment-checks",
 486          "Bound on number of runtime checks inserted by the vectorizer's loop versioning for alignment check",
 487          6, 0, 0)
 488
 489 DEFPARAM(PARAM_VECT_MAX_VERSION_FOR_ALIAS_CHECKS,
 490          "vect-max-version-for-alias-checks",
 491          "Bound on number of runtime checks inserted by the vectorizer's loop versioning for alias check",
 492          10, 0, 0)
 493
 494 DEFPARAM(PARAM_MAX_CSELIB_MEMORY_LOCATIONS,
 495          "max-cselib-memory-locations",
 496          "The maximum memory locations recorded by cselib",
 497          500, 0, 0)
 498
 499 #ifdef ENABLE_GC_ALWAYS_COLLECT
 500 # define GGC_MIN_EXPAND_DEFAULT 0
 501 # define GGC_MIN_HEAPSIZE_DEFAULT 0
 502 #else
 503 # define GGC_MIN_EXPAND_DEFAULT 30
 504 # define GGC_MIN_HEAPSIZE_DEFAULT 4096
 505 #endif
 506
 507 DEFPARAM(GGC_MIN_EXPAND,
 508          "ggc-min-expand",
 509          "Minimum heap expansion to trigger garbage collection, as a percentage of the total size of the heap",
 510          GGC_MIN_EXPAND_DEFAULT, 0, 0)
 511
 512 DEFPARAM(GGC_MIN_HEAPSIZE,
 513          "ggc-min-heapsize",
 514          "Minimum heap size before we start collecting garbage, in kilobytes",
 515          GGC_MIN_HEAPSIZE_DEFAULT, 0, 0)
 516
 517 #undef GGC_MIN_EXPAND_DEFAULT
 518 #undef GGC_MIN_HEAPSIZE_DEFAULT
 519
 520 DEFPARAM(PARAM_MAX_RELOAD_SEARCH_INSNS,
 521          "max-reload-search-insns",
 522          "The maximum number of instructions to search backward when looking for equivalent reload",
 523          100, 0, 0)
 524
 525 DEFPARAM(PARAM_MAX_SCHED_REGION_BLOCKS,
 526          "max-sched-region-blocks",
 527          "The maximum number of blocks in a region to be considered for interblock scheduling",
 528          10, 0, 0)
 529
 530 DEFPARAM(PARAM_MAX_SCHED_REGION_INSNS,
 531          "max-sched-region-insns",
 532          "The maximum number of insns in a region to be considered for interblock scheduling",
 533          100, 0, 0)
 534
 535 DEFPARAM(PARAM_MAX_PIPELINE_REGION_BLOCKS,
 536          "max-pipeline-region-blocks",
 537          "The maximum number of blocks in a region to be considered for interblock scheduling",
 538          15, 0, 0)
 539
 540 DEFPARAM(PARAM_MAX_PIPELINE_REGION_INSNS,
 541          "max-pipeline-region-insns",
 542          "The maximum number of insns in a region to be considered for interblock scheduling",
 543          200, 0, 0)
 544
 545 DEFPARAM(PARAM_MIN_SPEC_PROB,
 546          "min-spec-prob",
 547          "The minimum probability of reaching a source block for interblock speculative scheduling",
 548          40, 0, 0)
 549
 550 DEFPARAM(PARAM_MAX_SCHED_EXTEND_REGIONS_ITERS,
 551          "max-sched-extend-regions-iters",
 552          "The maximum number of iterations through CFG to extend regions",
 553          0, 0, 0)
 554
 555 DEFPARAM(PARAM_MAX_SCHED_INSN_CONFLICT_DELAY,
 556          "max-sched-insn-conflict-delay",
 557          "The maximum conflict delay for an insn to be considered for speculative motion",
 558          3, 1, 10)
 559
 560 DEFPARAM(PARAM_SCHED_SPEC_PROB_CUTOFF,
 561          "sched-spec-prob-cutoff",
 562          "The minimal probability of speculation success (in percents), so that speculative insn will be scheduled.",
 563          40, 0, 100)
 564
 565 DEFPARAM(PARAM_SELSCHED_MAX_LOOKAHEAD,
 566          "selsched-max-lookahead",
 567          "The maximum size of the lookahead window of selective scheduling",
 568          50, 0, 0)
 569
 570 DEFPARAM(PARAM_SELSCHED_MAX_SCHED_TIMES,
 571          "selsched-max-sched-times",
 572          "Maximum number of times that an insn could be scheduled",
 573          2, 0, 0)
 574
 575 DEFPARAM(PARAM_SELSCHED_INSNS_TO_RENAME,
 576          "selsched-insns-to-rename",
 577          "Maximum number of instructions in the ready list that are considered eligible for renaming",
 578          2, 0, 0)
 579
 580 DEFPARAM (PARAM_SCHED_MEM_TRUE_DEP_COST,
 581           "sched-mem-true-dep-cost",
 582           "Minimal distance between possibly conflicting store and load",
 583           1, 0, 0)
 584
 585 DEFPARAM(PARAM_MAX_LAST_VALUE_RTL,
 586          "max-last-value-rtl",
 587          "The maximum number of RTL nodes that can be recorded as combiner's last value",
 588          10000, 0, 0)
 589
 590 /* INTEGER_CST nodes are shared for values [{-1,0} .. N) for
 591    {signed,unsigned} integral types.  This determines N.
 592    Experimentation shows 256 to be a good value.  */
 593 DEFPARAM (PARAM_INTEGER_SHARE_LIMIT,
 594           "integer-share-limit",
 595           "The upper bound for sharing integer constants",
 596           256, 2, 2)
 597
 598 /* Incremental SSA updates for virtual operands may be very slow if
 599    there is a large number of mappings to process.  In those cases, it
 600    is faster to rewrite the virtual symbols from scratch as if they
 601    had been recently introduced.  This heuristic cannot be applied to
 602    SSA mappings for real SSA names, only symbols kept in FUD chains.
 603
 604    PARAM_MIN_VIRTUAL_MAPPINGS specifies the minimum number of virtual
 605    mappings that should be registered to trigger the heuristic.
 606
 607    PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO specifies the ratio between
 608    mappings and symbols.  If the number of virtual mappings is
 609    PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO bigger than the number of
 610    virtual symbols to be updated, then the updater switches to a full
 611    update for those symbols.  */
 612 DEFPARAM (PARAM_MIN_VIRTUAL_MAPPINGS,
 613           "min-virtual-mappings",
 614           "Minimum number of virtual mappings to consider switching to full virtual renames",
 615           100, 0, 0)
 616
 617 DEFPARAM (PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO,
 618           "virtual-mappings-ratio",
 619           "Ratio between virtual mappings and virtual symbols to do full virtual renames",
 620           3, 0, 0)
 621
 622 DEFPARAM (PARAM_SSP_BUFFER_SIZE,
 623           "ssp-buffer-size",
 624           "The lower bound for a buffer to be considered for stack smashing protection",
 625           8, 1, 0)
 626
 627 /* When we thread through a block we have to make copies of the
 628    statements within the block.  Clearly for large blocks the code
 629    duplication is bad.
 630
 631    PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS specifies the maximum number
 632    of statements and PHI nodes allowed in a block which is going to
 633    be duplicated for thread jumping purposes.
 634
 635    Some simple analysis showed that more than 99% of the jump
 636    threading opportunities are for blocks with less than 15
 637    statements.  So we can get the benefits of jump threading
 638    without excessive code bloat for pathological cases with the
 639    throttle set at 15 statements.  */
 640 DEFPARAM (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS,
 641           "max-jump-thread-duplication-stmts",
 642           "Maximum number of statements allowed in a block that needs to be duplicated when threading jumps",
 643           15, 0, 0)
 644
 645 /* This is the maximum number of fields a variable may have before the pointer analysis machinery
 646    will stop trying to treat it in a field-sensitive manner.
 647    There are programs out there with thousands of fields per structure, and handling them
 648    field-sensitively is not worth the cost.  */
 649 DEFPARAM (PARAM_MAX_FIELDS_FOR_FIELD_SENSITIVE,
 650           "max-fields-for-field-sensitive",
 651           "Maximum number of fields in a structure before pointer analysis treats the structure as a single variable",
 652           0, 0, 0)
 653
 654 DEFPARAM(PARAM_MAX_SCHED_READY_INSNS,
 655          "max-sched-ready-insns",
 656          "The maximum number of instructions ready to be issued to be considered by the scheduler during the first scheduling pass",
 657          100, 0, 0)
 658
 659 /* Prefetching and cache-optimizations related parameters.  Default values are
 660    usually set by machine description.  */
 661
 662 /* The number of insns executed before prefetch is completed.  */
 663
 664 DEFPARAM (PARAM_PREFETCH_LATENCY,
 665          "prefetch-latency",
 666          "The number of insns executed before prefetch is completed",
 667          200, 0, 0)
 668
 669 /* The number of prefetches that can run at the same time.  */
 670
 671 DEFPARAM (PARAM_SIMULTANEOUS_PREFETCHES,
 672           "simultaneous-prefetches",
 673           "The number of prefetches that can run at the same time",
 674           3, 0, 0)
 675
 676 /* The size of L1 cache in kB.  */
 677
 678 DEFPARAM (PARAM_L1_CACHE_SIZE,
 679           "l1-cache-size",
 680           "The size of L1 cache",
 681           64, 0, 0)
 682
 683 /* The size of L1 cache line in bytes.  */
 684
 685 DEFPARAM (PARAM_L1_CACHE_LINE_SIZE,
 686           "l1-cache-line-size",
 687           "The size of L1 cache line",
 688           32, 0, 0)
 689
 690 /* The size of L2 cache in kB.  */
 691
 692 DEFPARAM (PARAM_L2_CACHE_SIZE,
 693           "l2-cache-size",
 694           "The size of L2 cache",
 695           512, 0, 0)
 696
 697 /* Whether we should use canonical types rather than deep "structural"
 698    type checking.  Setting this value to 1 (the default) improves
 699    compilation performance in the C++ and Objective-C++ front end;
 700    this value should only be set to zero to work around bugs in the
 701    canonical type system by disabling it.  */
 702
 703 DEFPARAM (PARAM_USE_CANONICAL_TYPES,
 704           "use-canonical-types",
 705           "Whether to use canonical types",
 706           1, 0, 1)
 707
 708 DEFPARAM (PARAM_MAX_PARTIAL_ANTIC_LENGTH,
 709           "max-partial-antic-length",
 710           "Maximum length of partial antic set when performing tree pre optimization",
 711           100, 0, 0)
 712
 713 /* The following is used as a stop-gap limit for cases where really huge
 714    SCCs blow up memory and compile-time use too much.  If we hit this limit,
 715    SCCVN and such FRE and PRE will be not done at all for the current
 716    function.  */
 717
 718 DEFPARAM (PARAM_SCCVN_MAX_SCC_SIZE,
 719           "sccvn-max-scc-size",
 720           "Maximum size of a SCC before SCCVN stops processing a function",
 721           10000, 10, 0)
 722
 723 DEFPARAM (PARAM_IRA_MAX_LOOPS_NUM,
 724           "ira-max-loops-num",
 725           "Max loops number for regional RA",
 726           100, 0, 0)
 727
 728 DEFPARAM (PARAM_IRA_MAX_CONFLICT_TABLE_SIZE,
 729           "ira-max-conflict-table-size",
 730           "Max size of conflict table in MB",
 731           1000, 0, 0)
 732
 733 DEFPARAM (PARAM_IRA_LOOP_RESERVED_REGS,
 734           "ira-loop-reserved-regs",
 735           "The number of registers in each class kept unused by loop invariant motion",
 736           2, 0, 0)
 737
 738 /* Switch initialization conversion will refuse to create arrays that are
 739    bigger than this parameter times the number of switch branches.  */
 740
 741 DEFPARAM (PARAM_SWITCH_CONVERSION_BRANCH_RATIO,
 742           "switch-conversion-max-branch-ratio",
 743           "The maximum ratio between array size and switch branches for "
 744           "a switch conversion to take place",
 745           8, 1, 0)
 746
 747 /* Size of tiles when doing loop blocking.  */
 748
 749 DEFPARAM (PARAM_LOOP_BLOCK_TILE_SIZE,
 750           "loop-block-tile-size",
 751           "size of tiles for loop blocking",
 752           51, 0, 0)
 753
 754 /* Maximal number of parameters that we allow in a SCoP.  */
 755
 756 DEFPARAM (PARAM_GRAPHITE_MAX_NB_SCOP_PARAMS,
 757           "graphite-max-nb-scop-params",
 758           "maximum number of parameters in a SCoP",
 759           10, 0, 0)
 760
 761 /* Maximal number of basic blocks in the functions analyzed by Graphite.  */
 762
 763 DEFPARAM (PARAM_GRAPHITE_MAX_BBS_PER_FUNCTION,
 764           "graphite-max-bbs-per-function",
 765           "maximum number of basic blocks per function to be analyzed by Graphite",
 766           100, 0, 0)
 767
 768 /* Avoid doing loop invariant motion on very large loops.  */
 769
 770 DEFPARAM (PARAM_LOOP_INVARIANT_MAX_BBS_IN_LOOP,
 771           "loop-invariant-max-bbs-in-loop",
 772           "Max basic blocks number in loop for loop invariant motion",
 773           10000, 0, 0)
 774
 775 /* Avoid SLP vectorization of large basic blocks.  */
 776 DEFPARAM (PARAM_SLP_MAX_INSNS_IN_BB,
 777           "slp-max-insns-in-bb",
 778           "Maximum number of instructions in basic block to be considered for SLP vectorization",
 779           1000, 0, 0)
 780
 781 DEFPARAM (PARAM_MIN_INSN_TO_PREFETCH_RATIO,
 782           "min-insn-to-prefetch-ratio",
 783           "Min. ratio of insns to prefetches to enable prefetching for "
 784           "a loop with an unknown trip count",
 785           10, 0, 0)
 786
 787 DEFPARAM (PARAM_PREFETCH_MIN_INSN_TO_MEM_RATIO,
 788           "prefetch-min-insn-to-mem-ratio",
 789           "Min. ratio of insns to mem ops to enable prefetching in a loop",
 790           3, 0, 0)
 791
 792 /* Set maximum hash table size for var tracking.  */
 793
 794 DEFPARAM (PARAM_MAX_VARTRACK_SIZE,
 795           "max-vartrack-size",
 796           "Max. size of var tracking hash tables",
 797           50000000, 0, 0)
 798
 799 /* Set minimum insn uid for non-debug insns.  */
 800
 801 DEFPARAM (PARAM_MIN_NONDEBUG_INSN_UID,
 802           "min-nondebug-insn-uid",
 803           "The minimum UID to be used for a nondebug insn",
 804           0, 1, 0)
 805
 806 DEFPARAM (PARAM_IPA_SRA_PTR_GROWTH_FACTOR,
 807           "ipa-sra-ptr-growth-factor",
 808           "Maximum allowed growth of size of new parameters ipa-sra replaces "
 809           "a pointer to an aggregate with",
 810           2, 0, 0)
 811
 812 /*
 813 Local variables:
 814 mode:c
 815 End:
 816 */