gcc/params.def

   1 /* params.def - Run-time parameters.
   2    Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007
   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 number of fields in a variable with only implicit uses
  42    for which structure aliasing will consider trying to track each
  43    field.  The default is 5.  */
  44 DEFPARAM (PARAM_SALIAS_MAX_IMPLICIT_FIELDS,
  45           "salias-max-implicit-fields",
  46           "The maximum number of fields in a structure variable without direct structure accesses that GCC will attempt to track separately",
  47           5, 0, 0)
  48
  49 /* The maximum number of array elements structure aliasing will decompose
  50    an array for.  The default is 4.  */
  51 DEFPARAM (PARAM_SALIAS_MAX_ARRAY_ELEMENTS,
  52           "salias-max-array-elements",
  53           "The maximum number of elements in an array for wich we track its elements separately",
  54           4, 0, 0)
  55
  56 /* The maximum structure size at which the scalar replacement of
  57    aggregates (SRA) pass will perform block copies.  The default
  58    value, 0, implies that GCC will select the most appropriate size
  59    itself.  */
  60 DEFPARAM (PARAM_SRA_MAX_STRUCTURE_SIZE,
  61           "sra-max-structure-size",
  62           "The maximum structure size (in bytes) for which GCC will "
  63           "use by-element copies",
  64           0, 0, 0)
  65
  66 /* The maximum number of structure fields which the SRA pass will
  67    instantiate to avoid block copies.  The default value, 0, implies
  68    that GCC will select the appropriate value itself.  */
  69 DEFPARAM (PARAM_SRA_MAX_STRUCTURE_COUNT,
  70           "sra-max-structure-count",
  71           "The maximum number of structure fields for which GCC will "
  72           "use by-element copies",
  73           0, 0, 0)
  74
  75 /* The ratio between instantiated fields and the complete structure
  76    size.  We say that if the ratio of the number of bytes in
  77    instantiated fields to the number of bytes in the complete
  78    structure exceeds this parameter, or if the number of instantiated
  79    fields to the total number of fields exceeds this parameter, then
  80    block copies are not used.  The default is 75%.  */
  81 DEFPARAM (PARAM_SRA_FIELD_STRUCTURE_RATIO,
  82           "sra-field-structure-ratio",
  83           "The threshold ratio between instantiated fields and the total structure size",
  84           75, 0, 100)
  85
  86 /* The single function inlining limit. This is the maximum size
  87    of a function counted in internal gcc instructions (not in
  88    real machine instructions) that is eligible for inlining
  89    by the tree inliner.
  90    The default value is 450.
  91    Only functions marked inline (or methods defined in the class
  92    definition for C++) are affected by this.
  93    There are more restrictions to inlining: If inlined functions
  94    call other functions, the already inlined instructions are
  95    counted and once the recursive inline limit (see
  96    "max-inline-insns" parameter) is exceeded, the acceptable size
  97    gets decreased.  */
  98 DEFPARAM (PARAM_MAX_INLINE_INSNS_SINGLE,
  99           "max-inline-insns-single",
 100           "The maximum number of instructions in a single function eligible for inlining",
 101           450, 0, 0)
 102
 103 /* The single function inlining limit for functions that are
 104    inlined by virtue of -finline-functions (-O3).
 105    This limit should be chosen to be below or equal to the limit
 106    that is applied to functions marked inlined (or defined in the
 107    class declaration in C++) given by the "max-inline-insns-single"
 108    parameter.
 109    The default value is 90.  */
 110 DEFPARAM (PARAM_MAX_INLINE_INSNS_AUTO,
 111           "max-inline-insns-auto",
 112           "The maximum number of instructions when automatically inlining",
 113           90, 0, 0)
 114
 115 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE,
 116           "max-inline-insns-recursive",
 117           "The maximum number of instructions inline function can grow to via recursive inlining",
 118           450, 0, 0)
 119
 120 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE_AUTO,
 121           "max-inline-insns-recursive-auto",
 122           "The maximum number of instructions non-inline function can grow to via recursive inlining",
 123           450, 0, 0)
 124
 125 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH,
 126           "max-inline-recursive-depth",
 127           "The maximum depth of recursive inlining for inline functions",
 128           8, 0, 0)
 129
 130 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH_AUTO,
 131           "max-inline-recursive-depth-auto",
 132           "The maximum depth of recursive inlining for non-inline functions",
 133           8, 0, 0)
 134
 135 DEFPARAM (PARAM_MIN_INLINE_RECURSIVE_PROBABILITY,
 136           "min-inline-recursive-probability",
 137           "Inline recursively only when the probability of call being executed exceeds the parameter",
 138           10, 0, 0)
 139
 140 /* Limit the number of expansions created by the variable expansion
 141    optimization to avoid register pressure.  */
 142 DEFPARAM (PARAM_MAX_VARIABLE_EXPANSIONS,
 143           "max-variable-expansions-in-unroller",
 144           "If -fvariable-expansion-in-unroller is used, the maximum number of times that an individual variable will be expanded during loop unrolling",
 145           1, 0, 0)
 146
 147 /* Limit loop autovectorization to loops with large enough iteration count.  */
 148 DEFPARAM (PARAM_MIN_VECT_LOOP_BOUND,
 149           "min-vect-loop-bound",
 150           "If -ftree-vectorize is used, the minimal loop bound of a loop to be considered for vectorization",
 151           1, 1, 0)
 152
 153 /* The maximum number of instructions to consider when looking for an
 154    instruction to fill a delay slot.  If more than this arbitrary
 155    number of instructions is searched, the time savings from filling
 156    the delay slot will be minimal so stop searching.  Increasing
 157    values mean more aggressive optimization, making the compile time
 158    increase with probably small improvement in executable run time.  */
 159 DEFPARAM (PARAM_MAX_DELAY_SLOT_INSN_SEARCH,
 160           "max-delay-slot-insn-search",
 161           "The maximum number of instructions to consider to fill a delay slot",
 162           100, 0, 0)
 163
 164 /* When trying to fill delay slots, the maximum number of instructions
 165    to consider when searching for a block with valid live register
 166    information.  Increasing this arbitrarily chosen value means more
 167    aggressive optimization, increasing the compile time.  This
 168    parameter should be removed when the delay slot code is rewritten
 169    to maintain the control-flow graph.  */
 170 DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
 171          "max-delay-slot-live-search",
 172          "The maximum number of instructions to consider to find accurate live register information",
 173          333, 0, 0)
 174
 175 /* This parameter limits the number of branch elements that the
 176    scheduler will track anti-dependencies through without resetting
 177    the tracking mechanism.  Large functions with few calls or barriers
 178    can generate lists containing many 1000's of dependencies.  Generally
 179    the compiler either uses all available memory, or runs for far too long.  */
 180 DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
 181          "max-pending-list-length",
 182          "The maximum length of scheduling's pending operations list",
 183          32, 0, 0)
 184
 185 DEFPARAM(PARAM_LARGE_FUNCTION_INSNS,
 186          "large-function-insns",
 187          "The size of function body to be considered large",
 188          2700, 0, 0)
 189 DEFPARAM(PARAM_LARGE_FUNCTION_GROWTH,
 190          "large-function-growth",
 191          "Maximal growth due to inlining of large function (in percent)",
 192          100, 0, 0)
 193 DEFPARAM(PARAM_LARGE_UNIT_INSNS,
 194          "large-unit-insns",
 195          "The size of translation unit to be considered large",
 196          10000, 0, 0)
 197 DEFPARAM(PARAM_INLINE_UNIT_GROWTH,
 198          "inline-unit-growth",
 199          "how much can given compilation unit grow because of the inlining (in percent)",
 200          30, 0, 0)
 201 DEFPARAM(PARAM_INLINE_CALL_COST,
 202          "inline-call-cost",
 203          "expense of call operation relative to ordinary arithmetic operations",
 204          12, 0, 0)
 205 DEFPARAM(PARAM_LARGE_STACK_FRAME,
 206          "large-stack-frame",
 207          "The size of stack frame to be considered large",
 208          256, 0, 0)
 209 DEFPARAM(PARAM_STACK_FRAME_GROWTH,
 210          "large-stack-frame-growth",
 211          "Maximal stack frame growth due to inlining (in percent)",
 212          1000, 0, 0)
 213
 214 /* The GCSE optimization will be disabled if it would require
 215    significantly more memory than this value.  */
 216 DEFPARAM(PARAM_MAX_GCSE_MEMORY,
 217          "max-gcse-memory",
 218          "The maximum amount of memory to be allocated by GCSE",
 219          50 * 1024 * 1024, 0, 0)
 220 /* The number of repetitions of copy/const prop and PRE to run.  */
 221 DEFPARAM(PARAM_MAX_GCSE_PASSES,
 222         "max-gcse-passes",
 223         "The maximum number of passes to make when doing GCSE",
 224         1, 1, 0)
 225 /* This is the threshold ratio when to perform partial redundancy
 226    elimination after reload. We perform partial redundancy elimination
 227    when the following holds:
 228    (Redundant load execution count)
 229    ------------------------------- >= GCSE_AFTER_RELOAD_PARTIAL_FRACTION
 230    (Added loads execution count)                                          */
 231 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_PARTIAL_FRACTION,
 232         "gcse-after-reload-partial-fraction",
 233         "The threshold ratio for performing partial redundancy elimination after reload",
 234         3, 0, 0)
 235 /* This is the threshold ratio of the critical edges execution count compared to
 236    the redundant loads execution count that permits performing the load
 237    redundancy elimination in gcse after reload.  */
 238 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_CRITICAL_FRACTION,
 239         "gcse-after-reload-critical-fraction",
 240         "The threshold ratio of critical edges execution count that permit performing redundancy elimination after reload",
 241         10, 0, 0)
 242 /* This parameter limits the number of insns in a loop that will be unrolled,
 243    and by how much the loop is unrolled.
 244
 245    This limit should be at most half of the peeling limits:  loop unroller
 246    decides to not unroll loops that iterate fewer than 2*number of allowed
 247    unrollings and thus we would have loops that are neither peeled or unrolled
 248    otherwise.  */
 249 DEFPARAM(PARAM_MAX_UNROLLED_INSNS,
 250          "max-unrolled-insns",
 251          "The maximum number of instructions to consider to unroll in a loop",
 252          200, 0, 0)
 253 /* This parameter limits how many times the loop is unrolled depending
 254    on number of insns really executed in each iteration.  */
 255 DEFPARAM(PARAM_MAX_AVERAGE_UNROLLED_INSNS,
 256          "max-average-unrolled-insns",
 257          "The maximum number of instructions to consider to unroll in a loop on average",
 258          80, 0, 0)
 259 /* The maximum number of unrollings of a single loop.  */
 260 DEFPARAM(PARAM_MAX_UNROLL_TIMES,
 261         "max-unroll-times",
 262         "The maximum number of unrollings of a single loop",
 263         8, 0, 0)
 264 /* The maximum number of insns of a peeled loop.  */
 265 DEFPARAM(PARAM_MAX_PEELED_INSNS,
 266         "max-peeled-insns",
 267         "The maximum number of insns of a peeled loop",
 268         400, 0, 0)
 269 /* The maximum number of peelings of a single loop.  */
 270 DEFPARAM(PARAM_MAX_PEEL_TIMES,
 271         "max-peel-times",
 272         "The maximum number of peelings of a single loop",
 273         16, 0, 0)
 274 /* The maximum number of insns of a peeled loop.  */
 275 DEFPARAM(PARAM_MAX_COMPLETELY_PEELED_INSNS,
 276         "max-completely-peeled-insns",
 277         "The maximum number of insns of a completely peeled loop",
 278         400, 0, 0)
 279 /* The maximum number of peelings of a single loop that is peeled completely.  */
 280 DEFPARAM(PARAM_MAX_COMPLETELY_PEEL_TIMES,
 281         "max-completely-peel-times",
 282         "The maximum number of peelings of a single loop that is peeled completely",
 283         16, 0, 0)
 284 /* The maximum number of insns of a peeled loop that rolls only once.  */
 285 DEFPARAM(PARAM_MAX_ONCE_PEELED_INSNS,
 286         "max-once-peeled-insns",
 287         "The maximum number of insns of a peeled loop that rolls only once",
 288         400, 0, 0)
 289
 290 /* The maximum number of insns of an unswitched loop.  */
 291 DEFPARAM(PARAM_MAX_UNSWITCH_INSNS,
 292         "max-unswitch-insns",
 293         "The maximum number of insns of an unswitched loop",
 294         50, 0, 0)
 295 /* The maximum level of recursion in unswitch_single_loop.  */
 296 DEFPARAM(PARAM_MAX_UNSWITCH_LEVEL,
 297         "max-unswitch-level",
 298         "The maximum number of unswitchings in a single loop",
 299         3, 0, 0)
 300
 301 /* The maximum number of iterations of a loop the brute force algorithm
 302    for analysis of # of iterations of the loop tries to evaluate.  */
 303 DEFPARAM(PARAM_MAX_ITERATIONS_TO_TRACK,
 304         "max-iterations-to-track",
 305         "Bound on the number of iterations the brute force # of iterations analysis algorithm evaluates",
 306         1000, 0, 0)
 307 /* A cutoff to avoid costly computations of the number of iterations in
 308    the doloop transformation.  */
 309 DEFPARAM(PARAM_MAX_ITERATIONS_COMPUTATION_COST,
 310         "max-iterations-computation-cost",
 311         "Bound on the cost of an expression to compute the number of iterations",
 312         10, 0, 0)
 313
 314 /* This parameter is used to tune SMS MAX II calculations.  */
 315 DEFPARAM(PARAM_SMS_MAX_II_FACTOR,
 316          "sms-max-ii-factor",
 317          "A factor for tuning the upper bound that swing modulo scheduler uses for scheduling a loop",
 318          100, 0, 0)
 319 DEFPARAM(PARAM_SMS_DFA_HISTORY,
 320          "sms-dfa-history",
 321          "The number of cycles the swing modulo scheduler considers when checking conflicts using DFA",
 322          0, 0, 0)
 323 DEFPARAM(PARAM_SMS_LOOP_AVERAGE_COUNT_THRESHOLD,
 324          "sms-loop-average-count-threshold",
 325          "A threshold on the average loop count considered by the swing modulo scheduler",
 326          0, 0, 0)
 327
 328 DEFPARAM(HOT_BB_COUNT_FRACTION,
 329          "hot-bb-count-fraction",
 330          "Select fraction of the maximal count of repetitions of basic block in program given basic block needs to have to be considered hot",
 331          10000, 0, 0)
 332 DEFPARAM(HOT_BB_FREQUENCY_FRACTION,
 333          "hot-bb-frequency-fraction",
 334          "Select fraction of the maximal frequency of executions of basic block in function given basic block needs to have to be considered hot",
 335          1000, 0, 0)
 336
 337 /* For guessed profiles, the loops having unknown number of iterations
 338    are predicted to iterate relatively few (10) times at average.
 339    For functions containing one loop with large known number of iterations
 340    and other loops having unbounded loops we would end up predicting all
 341    the other loops cold that is not usually the case.  So we need to artificially
 342    flatten the profile.
 343
 344    We need to cut the maximal predicted iterations to large enough iterations
 345    so the loop appears important, but safely within HOT_BB_COUNT_FRACTION
 346    range.  */
 347
 348 DEFPARAM(PARAM_MAX_PREDICTED_ITERATIONS,
 349          "max-predicted-iterations",
 350          "The maximum number of loop iterations we predict statically",
 351          100, 0, 0)
 352 DEFPARAM(TRACER_DYNAMIC_COVERAGE_FEEDBACK,
 353          "tracer-dynamic-coverage-feedback",
 354          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is available",
 355          95, 0, 100)
 356 DEFPARAM(TRACER_DYNAMIC_COVERAGE,
 357          "tracer-dynamic-coverage",
 358          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is not available",
 359          75, 0, 100)
 360 DEFPARAM(TRACER_MAX_CODE_GROWTH,
 361          "tracer-max-code-growth",
 362          "Maximal code growth caused by tail duplication (in percent)",
 363          100, 0, 0)
 364 DEFPARAM(TRACER_MIN_BRANCH_RATIO,
 365          "tracer-min-branch-ratio",
 366          "Stop reverse growth if the reverse probability of best edge is less than this threshold (in percent)",
 367          10, 0, 100)
 368 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK,
 369          "tracer-min-branch-probability-feedback",
 370          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is available",
 371          80, 0, 100)
 372 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY,
 373          "tracer-min-branch-probability",
 374          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is not available",
 375          50, 0, 100)
 376
 377 /* The maximum number of incoming edges to consider for crossjumping.  */
 378 DEFPARAM(PARAM_MAX_CROSSJUMP_EDGES,
 379          "max-crossjump-edges",
 380          "The maximum number of incoming edges to consider for crossjumping",
 381          100, 0, 0)
 382
 383 /* The minimum number of matching instructions to consider for crossjumping.  */
 384 DEFPARAM(PARAM_MIN_CROSSJUMP_INSNS,
 385      "min-crossjump-insns",
 386      "The minimum number of matching instructions to consider for crossjumping",
 387      5, 0, 0)
 388
 389 /* The maximum number expansion factor when copying basic blocks.  */
 390 DEFPARAM(PARAM_MAX_GROW_COPY_BB_INSNS,
 391      "max-grow-copy-bb-insns",
 392      "The maximum expansion factor when copying basic blocks",
 393      8, 0, 0)
 394
 395 /* The maximum number of insns to duplicate when unfactoring computed gotos.  */
 396 DEFPARAM(PARAM_MAX_GOTO_DUPLICATION_INSNS,
 397      "max-goto-duplication-insns",
 398      "The maximum number of insns to duplicate when unfactoring computed gotos",
 399      8, 0, 0)
 400
 401 /* The maximum length of path considered in cse.  */
 402 DEFPARAM(PARAM_MAX_CSE_PATH_LENGTH,
 403          "max-cse-path-length",
 404          "The maximum length of path considered in cse",
 405          10, 0, 0)
 406 DEFPARAM(PARAM_MAX_CSE_INSNS,
 407          "max-cse-insns",
 408          "The maximum instructions CSE process before flushing",
 409          1000, 0, 0)
 410
 411 /* The cost of expression in loop invariant motion that is considered
 412    expensive.  */
 413 DEFPARAM(PARAM_LIM_EXPENSIVE,
 414          "lim-expensive",
 415          "The minimum cost of an expensive expression in the loop invariant motion",
 416          20, 0, 0)
 417
 418 /* Bound on number of candidates for induction variables below that
 419    all candidates are considered for each use in induction variable
 420    optimizations.  */
 421
 422 DEFPARAM(PARAM_IV_CONSIDER_ALL_CANDIDATES_BOUND,
 423          "iv-consider-all-candidates-bound",
 424          "Bound on number of candidates below that all candidates are considered in iv optimizations",
 425          30, 0, 0)
 426
 427 /* The induction variable optimizations give up on loops that contain more
 428    induction variable uses.  */
 429
 430 DEFPARAM(PARAM_IV_MAX_CONSIDERED_USES,
 431          "iv-max-considered-uses",
 432          "Bound on number of iv uses in loop optimized in iv optimizations",
 433          250, 0, 0)
 434
 435 /* If there are at most this number of ivs in the set, try removing unnecessary
 436    ivs from the set always.  */
 437
 438 DEFPARAM(PARAM_IV_ALWAYS_PRUNE_CAND_SET_BOUND,
 439          "iv-always-prune-cand-set-bound",
 440          "If number of candidates in the set is smaller, we always try to remove unused ivs during its optimization",
 441          10, 0, 0)
 442
 443 DEFPARAM(PARAM_SCEV_MAX_EXPR_SIZE,
 444          "scev-max-expr-size",
 445          "Bound on size of expressions used in the scalar evolutions analyzer",
 446          20, 0, 0)
 447
 448 DEFPARAM(PARAM_OMEGA_MAX_VARS,
 449          "omega-max-vars",
 450          "Bound on the number of variables in Omega constraint systems",
 451          128, 0, 0)
 452
 453 DEFPARAM(PARAM_OMEGA_MAX_GEQS,
 454          "omega-max-geqs",
 455          "Bound on the number of inequalities in Omega constraint systems",
 456          256, 0, 0)
 457
 458 DEFPARAM(PARAM_OMEGA_MAX_EQS,
 459          "omega-max-eqs",
 460          "Bound on the number of equalities in Omega constraint systems",
 461          128, 0, 0)
 462
 463 DEFPARAM(PARAM_OMEGA_MAX_WILD_CARDS,
 464          "omega-max-wild-cards",
 465          "Bound on the number of wild cards in Omega constraint systems",
 466          18, 0, 0)
 467
 468 DEFPARAM(PARAM_OMEGA_HASH_TABLE_SIZE,
 469          "omega-hash-table-size",
 470          "Bound on the size of the hash table in Omega constraint systems",
 471          550, 0, 0)
 472
 473 DEFPARAM(PARAM_OMEGA_MAX_KEYS,
 474          "omega-max-keys",
 475          "Bound on the number of keys in Omega constraint systems",
 476          500, 0, 0)
 477
 478 DEFPARAM(PARAM_OMEGA_ELIMINATE_REDUNDANT_CONSTRAINTS,
 479          "omega-eliminate-redundant-constraints",
 480          "When set to 1, use expensive methods to eliminate all redundant constraints",
 481          0, 0, 1)
 482
 483 DEFPARAM(PARAM_VECT_MAX_VERSION_FOR_ALIGNMENT_CHECKS,
 484          "vect-max-version-for-alignment-checks",
 485          "Bound on number of runtime checks inserted by the vectorizer's loop versioning for alignment check",
 486          6, 0, 0)
 487
 488 DEFPARAM(PARAM_VECT_MAX_VERSION_FOR_ALIAS_CHECKS,
 489          "vect-max-version-for-alias-checks",
 490          "Bound on number of runtime checks inserted by the vectorizer's loop versioning for alias check",
 491          10, 0, 0)
 492
 493 DEFPARAM(PARAM_MAX_CSELIB_MEMORY_LOCATIONS,
 494          "max-cselib-memory-locations",
 495          "The maximum memory locations recorded by cselib",
 496          500, 0, 0)
 497 DEFPARAM(PARAM_MAX_FLOW_MEMORY_LOCATIONS,
 498          "max-flow-memory-locations",
 499          "The maximum memory locations recorded by flow",
 500          100, 0, 0)
 501
 502 #ifdef ENABLE_GC_ALWAYS_COLLECT
 503 # define GGC_MIN_EXPAND_DEFAULT 0
 504 # define GGC_MIN_HEAPSIZE_DEFAULT 0
 505 #else
 506 # define GGC_MIN_EXPAND_DEFAULT 30
 507 # define GGC_MIN_HEAPSIZE_DEFAULT 4096
 508 #endif
 509
 510 DEFPARAM(GGC_MIN_EXPAND,
 511          "ggc-min-expand",
 512          "Minimum heap expansion to trigger garbage collection, as a percentage of the total size of the heap",
 513          GGC_MIN_EXPAND_DEFAULT, 0, 0)
 514
 515 DEFPARAM(GGC_MIN_HEAPSIZE,
 516          "ggc-min-heapsize",
 517          "Minimum heap size before we start collecting garbage, in kilobytes",
 518          GGC_MIN_HEAPSIZE_DEFAULT, 0, 0)
 519
 520 #undef GGC_MIN_EXPAND_DEFAULT
 521 #undef GGC_MIN_HEAPSIZE_DEFAULT
 522
 523 DEFPARAM(PARAM_MAX_RELOAD_SEARCH_INSNS,
 524          "max-reload-search-insns",
 525          "The maximum number of instructions to search backward when looking for equivalent reload",
 526          100, 0, 0)
 527
 528 DEFPARAM(PARAM_MAX_ALIASED_VOPS,
 529          "max-aliased-vops",
 530          "The maximum number of virtual operators that a function is allowed to have before triggering memory partitioning heuristics",
 531          100, 0, 0)
 532
 533 DEFPARAM(PARAM_AVG_ALIASED_VOPS,
 534          "avg-aliased-vops",
 535          "The average number of virtual operators that memory statements are allowed to have before triggering memory partitioning heuristics",
 536          1, 0, 0)
 537
 538 DEFPARAM(PARAM_MAX_SCHED_REGION_BLOCKS,
 539          "max-sched-region-blocks",
 540          "The maximum number of blocks in a region to be considered for interblock scheduling",
 541          10, 0, 0)
 542
 543 DEFPARAM(PARAM_MAX_SCHED_REGION_INSNS,
 544          "max-sched-region-insns",
 545          "The maximum number of insns in a region to be considered for interblock scheduling",
 546          100, 0, 0)
 547
 548 DEFPARAM(PARAM_MIN_SPEC_PROB,
 549          "min-spec-prob",
 550          "The minimum probability of reaching a source block for interblock speculative scheduling",
 551          40, 0, 0)
 552
 553 DEFPARAM(PARAM_MAX_SCHED_EXTEND_REGIONS_ITERS,
 554          "max-sched-extend-regions-iters",
 555          "The maximum number of iterations through CFG to extend regions",
 556          0, 0, 0)
 557
 558 DEFPARAM(PARAM_MAX_SCHED_INSN_CONFLICT_DELAY,
 559          "max-sched-insn-conflict-delay",
 560          "The maximum conflict delay for an insn to be considered for speculative motion",
 561          3, 1, 10)
 562
 563 DEFPARAM(PARAM_SCHED_SPEC_PROB_CUTOFF,
 564          "sched-spec-prob-cutoff",
 565          "The minimal probability of speculation success (in percents), so that speculative insn will be scheduled.",
 566          40, 0, 100)
 567
 568 DEFPARAM(PARAM_MAX_LAST_VALUE_RTL,
 569          "max-last-value-rtl",
 570          "The maximum number of RTL nodes that can be recorded as combiner's last value",
 571          10000, 0, 0)
 572
 573 /* INTEGER_CST nodes are shared for values [{-1,0} .. N) for
 574    {signed,unsigned} integral types.  This determines N.
 575    Experimentation shows 256 to be a good value.  */
 576 DEFPARAM (PARAM_INTEGER_SHARE_LIMIT,
 577           "integer-share-limit",
 578           "The upper bound for sharing integer constants",
 579           256, 2, 2)
 580
 581 /* Incremental SSA updates for virtual operands may be very slow if
 582    there is a large number of mappings to process.  In those cases, it
 583    is faster to rewrite the virtual symbols from scratch as if they
 584    had been recently introduced.  This heuristic cannot be applied to
 585    SSA mappings for real SSA names, only symbols kept in FUD chains.
 586
 587    PARAM_MIN_VIRTUAL_MAPPINGS specifies the minimum number of virtual
 588    mappings that should be registered to trigger the heuristic.
 589
 590    PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO specifies the ratio between
 591    mappings and symbols.  If the number of virtual mappings is
 592    PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO bigger than the number of
 593    virtual symbols to be updated, then the updater switches to a full
 594    update for those symbols.  */
 595 DEFPARAM (PARAM_MIN_VIRTUAL_MAPPINGS,
 596           "min-virtual-mappings",
 597           "Minimum number of virtual mappings to consider switching to full virtual renames",
 598           100, 0, 0)
 599
 600 DEFPARAM (PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO,
 601           "virtual-mappings-ratio",
 602           "Ratio between virtual mappings and virtual symbols to do full virtual renames",
 603           3, 0, 0)
 604
 605 DEFPARAM (PARAM_SSP_BUFFER_SIZE,
 606           "ssp-buffer-size",
 607           "The lower bound for a buffer to be considered for stack smashing protection",
 608           8, 1, 0)
 609
 610 /* When we thread through a block we have to make copies of the
 611    statements within the block.  Clearly for large blocks the code
 612    duplication is bad.
 613
 614    PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS specifies the maximum number
 615    of statements and PHI nodes allowed in a block which is going to
 616    be duplicated for thread jumping purposes.
 617
 618    Some simple analysis showed that more than 99% of the jump
 619    threading opportunities are for blocks with less than 15
 620    statements.  So we can get the benefits of jump threading
 621    without excessive code bloat for pathological cases with the
 622    throttle set at 15 statements.  */
 623 DEFPARAM (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS,
 624           "max-jump-thread-duplication-stmts",
 625           "Maximum number of statements allowed in a block that needs to be duplicated when threading jumps",
 626           15, 0, 0)
 627
 628 /* This is the maximum number of fields a variable may have before the pointer analysis machinery
 629    will stop trying to treat it in a field-sensitive manner.
 630    There are programs out there with thousands of fields per structure, and handling them
 631    field-sensitively is not worth the cost.  */
 632 DEFPARAM (PARAM_MAX_FIELDS_FOR_FIELD_SENSITIVE,
 633           "max-fields-for-field-sensitive",
 634           "Maximum number of fields in a structure before pointer analysis treats the structure as a single variable",
 635           100, 0, 0)
 636
 637 DEFPARAM(PARAM_MAX_SCHED_READY_INSNS,
 638          "max-sched-ready-insns",
 639          "The maximum number of instructions ready to be issued to be considered by the scheduler during the first scheduling pass",
 640          100, 0, 0)
 641
 642 /* Prefetching and cache-optimizations related parameters.  Default values are
 643    usually set by machine description.  */
 644
 645 /* The number of insns executed before prefetch is completed.  */
 646
 647 DEFPARAM (PARAM_PREFETCH_LATENCY,
 648          "prefetch-latency",
 649          "The number of insns executed before prefetch is completed",
 650          200, 0, 0)
 651
 652 /* The number of prefetches that can run at the same time.  */
 653
 654 DEFPARAM (PARAM_SIMULTANEOUS_PREFETCHES,
 655           "simultaneous-prefetches",
 656           "The number of prefetches that can run at the same time",
 657           3, 0, 0)
 658
 659 /* The size of L1 cache in kB.  */
 660
 661 DEFPARAM (PARAM_L1_CACHE_SIZE,
 662           "l1-cache-size",
 663           "The size of L1 cache",
 664           64, 0, 0)
 665
 666 /* The size of L1 cache line in bytes.  */
 667
 668 DEFPARAM (PARAM_L1_CACHE_LINE_SIZE,
 669           "l1-cache-line-size",
 670           "The size of L1 cache line",
 671           32, 0, 0)
 672
 673 /* The size of L2 cache in kB.  */
 674
 675 DEFPARAM (PARAM_L2_CACHE_SIZE,
 676           "l2-cache-size",
 677           "The size of L2 cache",
 678           512, 0, 0)
 679
 680 /* Whether we should use canonical types rather than deep "structural"
 681    type checking.  Setting this value to 1 (the default) improves
 682    compilation performance in the C++ and Objective-C++ front end;
 683    this value should only be set to zero to work around bugs in the
 684    canonical type system by disabling it.  */
 685
 686 DEFPARAM (PARAM_USE_CANONICAL_TYPES,
 687           "use-canonical-types",
 688           "Whether to use canonical types",
 689           1, 0, 1)
 690 /*
 691 Local variables:
 692 mode:c
 693 End:
 694 */