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 threshold ratio between current and hottest structure counts.
  87    We say that if the ratio of the current structure count,
  88    calculated by profiling, to the hottest structure count
  89    in the program is less than this parameter, then structure
  90    reorganization is not applied. The default is 10%.  */
  91 DEFPARAM (PARAM_STRUCT_REORG_COLD_STRUCT_RATIO,
  92           "struct-reorg-cold-struct-ratio",
  93           "The threshold ratio between current and hottest structure counts",
  94           10, 0, 100)
  95
  96 /* The single function inlining limit. This is the maximum size
  97    of a function counted in internal gcc instructions (not in
  98    real machine instructions) that is eligible for inlining
  99    by the tree inliner.
 100    The default value is 450.
 101    Only functions marked inline (or methods defined in the class
 102    definition for C++) are affected by this.
 103    There are more restrictions to inlining: If inlined functions
 104    call other functions, the already inlined instructions are
 105    counted and once the recursive inline limit (see
 106    "max-inline-insns" parameter) is exceeded, the acceptable size
 107    gets decreased.  */
 108 DEFPARAM (PARAM_MAX_INLINE_INSNS_SINGLE,
 109           "max-inline-insns-single",
 110           "The maximum number of instructions in a single function eligible for inlining",
 111           450, 0, 0)
 112
 113 /* The single function inlining limit for functions that are
 114    inlined by virtue of -finline-functions (-O3).
 115    This limit should be chosen to be below or equal to the limit
 116    that is applied to functions marked inlined (or defined in the
 117    class declaration in C++) given by the "max-inline-insns-single"
 118    parameter.
 119    The default value is 90.  */
 120 DEFPARAM (PARAM_MAX_INLINE_INSNS_AUTO,
 121           "max-inline-insns-auto",
 122           "The maximum number of instructions when automatically inlining",
 123           90, 0, 0)
 124
 125 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE,
 126           "max-inline-insns-recursive",
 127           "The maximum number of instructions inline function can grow to via recursive inlining",
 128           450, 0, 0)
 129
 130 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE_AUTO,
 131           "max-inline-insns-recursive-auto",
 132           "The maximum number of instructions non-inline function can grow to via recursive inlining",
 133           450, 0, 0)
 134
 135 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH,
 136           "max-inline-recursive-depth",
 137           "The maximum depth of recursive inlining for inline functions",
 138           8, 0, 0)
 139
 140 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH_AUTO,
 141           "max-inline-recursive-depth-auto",
 142           "The maximum depth of recursive inlining for non-inline functions",
 143           8, 0, 0)
 144
 145 DEFPARAM (PARAM_MIN_INLINE_RECURSIVE_PROBABILITY,
 146           "min-inline-recursive-probability",
 147           "Inline recursively only when the probability of call being executed exceeds the parameter",
 148           10, 0, 0)
 149
 150 /* Limit the number of expansions created by the variable expansion
 151    optimization to avoid register pressure.  */
 152 DEFPARAM (PARAM_MAX_VARIABLE_EXPANSIONS,
 153           "max-variable-expansions-in-unroller",
 154           "If -fvariable-expansion-in-unroller is used, the maximum number of times that an individual variable will be expanded during loop unrolling",
 155           1, 0, 0)
 156
 157 /* Limit loop autovectorization to loops with large enough iteration count.  */
 158 DEFPARAM (PARAM_MIN_VECT_LOOP_BOUND,
 159           "min-vect-loop-bound",
 160           "If -ftree-vectorize is used, the minimal loop bound of a loop to be considered for vectorization",
 161           1, 1, 0)
 162
 163 /* The maximum number of instructions to consider when looking for an
 164    instruction to fill a delay slot.  If more than this arbitrary
 165    number of instructions is searched, the time savings from filling
 166    the delay slot will be minimal so stop searching.  Increasing
 167    values mean more aggressive optimization, making the compile time
 168    increase with probably small improvement in executable run time.  */
 169 DEFPARAM (PARAM_MAX_DELAY_SLOT_INSN_SEARCH,
 170           "max-delay-slot-insn-search",
 171           "The maximum number of instructions to consider to fill a delay slot",
 172           100, 0, 0)
 173
 174 /* When trying to fill delay slots, the maximum number of instructions
 175    to consider when searching for a block with valid live register
 176    information.  Increasing this arbitrarily chosen value means more
 177    aggressive optimization, increasing the compile time.  This
 178    parameter should be removed when the delay slot code is rewritten
 179    to maintain the control-flow graph.  */
 180 DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
 181          "max-delay-slot-live-search",
 182          "The maximum number of instructions to consider to find accurate live register information",
 183          333, 0, 0)
 184
 185 /* This parameter limits the number of branch elements that the
 186    scheduler will track anti-dependencies through without resetting
 187    the tracking mechanism.  Large functions with few calls or barriers
 188    can generate lists containing many 1000's of dependencies.  Generally
 189    the compiler either uses all available memory, or runs for far too long.  */
 190 DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
 191          "max-pending-list-length",
 192          "The maximum length of scheduling's pending operations list",
 193          32, 0, 0)
 194
 195 DEFPARAM(PARAM_LARGE_FUNCTION_INSNS,
 196          "large-function-insns",
 197          "The size of function body to be considered large",
 198          2700, 0, 0)
 199 DEFPARAM(PARAM_LARGE_FUNCTION_GROWTH,
 200          "large-function-growth",
 201          "Maximal growth due to inlining of large function (in percent)",
 202          100, 0, 0)
 203 DEFPARAM(PARAM_LARGE_UNIT_INSNS,
 204          "large-unit-insns",
 205          "The size of translation unit to be considered large",
 206          10000, 0, 0)
 207 DEFPARAM(PARAM_INLINE_UNIT_GROWTH,
 208          "inline-unit-growth",
 209          "how much can given compilation unit grow because of the inlining (in percent)",
 210          30, 0, 0)
 211 DEFPARAM(PARAM_INLINE_CALL_COST,
 212          "inline-call-cost",
 213          "expense of call operation relative to ordinary arithmetic operations",
 214          12, 0, 0)
 215 DEFPARAM(PARAM_LARGE_STACK_FRAME,
 216          "large-stack-frame",
 217          "The size of stack frame to be considered large",
 218          256, 0, 0)
 219 DEFPARAM(PARAM_STACK_FRAME_GROWTH,
 220          "large-stack-frame-growth",
 221          "Maximal stack frame growth due to inlining (in percent)",
 222          1000, 0, 0)
 223
 224 /* The GCSE optimization will be disabled if it would require
 225    significantly more memory than this value.  */
 226 DEFPARAM(PARAM_MAX_GCSE_MEMORY,
 227          "max-gcse-memory",
 228          "The maximum amount of memory to be allocated by GCSE",
 229          50 * 1024 * 1024, 0, 0)
 230 /* The number of repetitions of copy/const prop and PRE to run.  */
 231 DEFPARAM(PARAM_MAX_GCSE_PASSES,
 232         "max-gcse-passes",
 233         "The maximum number of passes to make when doing GCSE",
 234         1, 1, 0)
 235 /* This is the threshold ratio when to perform partial redundancy
 236    elimination after reload. We perform partial redundancy elimination
 237    when the following holds:
 238    (Redundant load execution count)
 239    ------------------------------- >= GCSE_AFTER_RELOAD_PARTIAL_FRACTION
 240    (Added loads execution count)                                          */
 241 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_PARTIAL_FRACTION,
 242         "gcse-after-reload-partial-fraction",
 243         "The threshold ratio for performing partial redundancy elimination after reload",
 244         3, 0, 0)
 245 /* This is the threshold ratio of the critical edges execution count compared to
 246    the redundant loads execution count that permits performing the load
 247    redundancy elimination in gcse after reload.  */
 248 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_CRITICAL_FRACTION,
 249         "gcse-after-reload-critical-fraction",
 250         "The threshold ratio of critical edges execution count that permit performing redundancy elimination after reload",
 251         10, 0, 0)
 252 /* This parameter limits the number of insns in a loop that will be unrolled,
 253    and by how much the loop is unrolled.
 254
 255    This limit should be at most half of the peeling limits:  loop unroller
 256    decides to not unroll loops that iterate fewer than 2*number of allowed
 257    unrollings and thus we would have loops that are neither peeled or unrolled
 258    otherwise.  */
 259 DEFPARAM(PARAM_MAX_UNROLLED_INSNS,
 260          "max-unrolled-insns",
 261          "The maximum number of instructions to consider to unroll in a loop",
 262          200, 0, 0)
 263 /* This parameter limits how many times the loop is unrolled depending
 264    on number of insns really executed in each iteration.  */
 265 DEFPARAM(PARAM_MAX_AVERAGE_UNROLLED_INSNS,
 266          "max-average-unrolled-insns",
 267          "The maximum number of instructions to consider to unroll in a loop on average",
 268          80, 0, 0)
 269 /* The maximum number of unrollings of a single loop.  */
 270 DEFPARAM(PARAM_MAX_UNROLL_TIMES,
 271         "max-unroll-times",
 272         "The maximum number of unrollings of a single loop",
 273         8, 0, 0)
 274 /* The maximum number of insns of a peeled loop.  */
 275 DEFPARAM(PARAM_MAX_PEELED_INSNS,
 276         "max-peeled-insns",
 277         "The maximum number of insns of a peeled loop",
 278         400, 0, 0)
 279 /* The maximum number of peelings of a single loop.  */
 280 DEFPARAM(PARAM_MAX_PEEL_TIMES,
 281         "max-peel-times",
 282         "The maximum number of peelings of a single loop",
 283         16, 0, 0)
 284 /* The maximum number of insns of a peeled loop.  */
 285 DEFPARAM(PARAM_MAX_COMPLETELY_PEELED_INSNS,
 286         "max-completely-peeled-insns",
 287         "The maximum number of insns of a completely peeled loop",
 288         400, 0, 0)
 289 /* The maximum number of peelings of a single loop that is peeled completely.  */
 290 DEFPARAM(PARAM_MAX_COMPLETELY_PEEL_TIMES,
 291         "max-completely-peel-times",
 292         "The maximum number of peelings of a single loop that is peeled completely",
 293         16, 0, 0)
 294 /* The maximum number of insns of a peeled loop that rolls only once.  */
 295 DEFPARAM(PARAM_MAX_ONCE_PEELED_INSNS,
 296         "max-once-peeled-insns",
 297         "The maximum number of insns of a peeled loop that rolls only once",
 298         400, 0, 0)
 299
 300 /* The maximum number of insns of an unswitched loop.  */
 301 DEFPARAM(PARAM_MAX_UNSWITCH_INSNS,
 302         "max-unswitch-insns",
 303         "The maximum number of insns of an unswitched loop",
 304         50, 0, 0)
 305 /* The maximum level of recursion in unswitch_single_loop.  */
 306 DEFPARAM(PARAM_MAX_UNSWITCH_LEVEL,
 307         "max-unswitch-level",
 308         "The maximum number of unswitchings in a single loop",
 309         3, 0, 0)
 310
 311 /* The maximum number of iterations of a loop the brute force algorithm
 312    for analysis of # of iterations of the loop tries to evaluate.  */
 313 DEFPARAM(PARAM_MAX_ITERATIONS_TO_TRACK,
 314         "max-iterations-to-track",
 315         "Bound on the number of iterations the brute force # of iterations analysis algorithm evaluates",
 316         1000, 0, 0)
 317 /* A cutoff to avoid costly computations of the number of iterations in
 318    the doloop transformation.  */
 319 DEFPARAM(PARAM_MAX_ITERATIONS_COMPUTATION_COST,
 320         "max-iterations-computation-cost",
 321         "Bound on the cost of an expression to compute the number of iterations",
 322         10, 0, 0)
 323
 324 /* This parameter is used to tune SMS MAX II calculations.  */
 325 DEFPARAM(PARAM_SMS_MAX_II_FACTOR,
 326          "sms-max-ii-factor",
 327          "A factor for tuning the upper bound that swing modulo scheduler uses for scheduling a loop",
 328          100, 0, 0)
 329 DEFPARAM(PARAM_SMS_DFA_HISTORY,
 330          "sms-dfa-history",
 331          "The number of cycles the swing modulo scheduler considers when checking conflicts using DFA",
 332          0, 0, 0)
 333 DEFPARAM(PARAM_SMS_LOOP_AVERAGE_COUNT_THRESHOLD,
 334          "sms-loop-average-count-threshold",
 335          "A threshold on the average loop count considered by the swing modulo scheduler",
 336          0, 0, 0)
 337
 338 DEFPARAM(HOT_BB_COUNT_FRACTION,
 339          "hot-bb-count-fraction",
 340          "Select fraction of the maximal count of repetitions of basic block in program given basic block needs to have to be considered hot",
 341          10000, 0, 0)
 342 DEFPARAM(HOT_BB_FREQUENCY_FRACTION,
 343          "hot-bb-frequency-fraction",
 344          "Select fraction of the maximal frequency of executions of basic block in function given basic block needs to have to be considered hot",
 345          1000, 0, 0)
 346
 347 DEFPARAM (PARAM_ALIGN_THRESHOLD,
 348           "align-threshold",
 349           "Select fraction of the maximal frequency of executions of basic block in function given basic block get alignment",
 350           100, 0, 0)
 351
 352 DEFPARAM (PARAM_ALIGN_LOOP_ITERATIONS,
 353           "align-loop-iterations",
 354           "Loops iterating at least selected number of iterations will get loop alignement.",
 355           4, 0, 0)
 356
 357 /* For guessed profiles, the loops having unknown number of iterations
 358    are predicted to iterate relatively few (10) times at average.
 359    For functions containing one loop with large known number of iterations
 360    and other loops having unbounded loops we would end up predicting all
 361    the other loops cold that is not usually the case.  So we need to artificially
 362    flatten the profile.
 363
 364    We need to cut the maximal predicted iterations to large enough iterations
 365    so the loop appears important, but safely within HOT_BB_COUNT_FRACTION
 366    range.  */
 367
 368 DEFPARAM(PARAM_MAX_PREDICTED_ITERATIONS,
 369          "max-predicted-iterations",
 370          "The maximum number of loop iterations we predict statically",
 371          100, 0, 0)
 372 DEFPARAM(TRACER_DYNAMIC_COVERAGE_FEEDBACK,
 373          "tracer-dynamic-coverage-feedback",
 374          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is available",
 375          95, 0, 100)
 376 DEFPARAM(TRACER_DYNAMIC_COVERAGE,
 377          "tracer-dynamic-coverage",
 378          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is not available",
 379          75, 0, 100)
 380 DEFPARAM(TRACER_MAX_CODE_GROWTH,
 381          "tracer-max-code-growth",
 382          "Maximal code growth caused by tail duplication (in percent)",
 383          100, 0, 0)
 384 DEFPARAM(TRACER_MIN_BRANCH_RATIO,
 385          "tracer-min-branch-ratio",
 386          "Stop reverse growth if the reverse probability of best edge is less than this threshold (in percent)",
 387          10, 0, 100)
 388 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK,
 389          "tracer-min-branch-probability-feedback",
 390          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is available",
 391          80, 0, 100)
 392 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY,
 393          "tracer-min-branch-probability",
 394          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is not available",
 395          50, 0, 100)
 396
 397 /* The maximum number of incoming edges to consider for crossjumping.  */
 398 DEFPARAM(PARAM_MAX_CROSSJUMP_EDGES,
 399          "max-crossjump-edges",
 400          "The maximum number of incoming edges to consider for crossjumping",
 401          100, 0, 0)
 402
 403 /* The minimum number of matching instructions to consider for crossjumping.  */
 404 DEFPARAM(PARAM_MIN_CROSSJUMP_INSNS,
 405      "min-crossjump-insns",
 406      "The minimum number of matching instructions to consider for crossjumping",
 407      5, 0, 0)
 408
 409 /* The maximum number expansion factor when copying basic blocks.  */
 410 DEFPARAM(PARAM_MAX_GROW_COPY_BB_INSNS,
 411      "max-grow-copy-bb-insns",
 412      "The maximum expansion factor when copying basic blocks",
 413      8, 0, 0)
 414
 415 /* The maximum number of insns to duplicate when unfactoring computed gotos.  */
 416 DEFPARAM(PARAM_MAX_GOTO_DUPLICATION_INSNS,
 417      "max-goto-duplication-insns",
 418      "The maximum number of insns to duplicate when unfactoring computed gotos",
 419      8, 0, 0)
 420
 421 /* The maximum length of path considered in cse.  */
 422 DEFPARAM(PARAM_MAX_CSE_PATH_LENGTH,
 423          "max-cse-path-length",
 424          "The maximum length of path considered in cse",
 425          10, 0, 0)
 426 DEFPARAM(PARAM_MAX_CSE_INSNS,
 427          "max-cse-insns",
 428          "The maximum instructions CSE process before flushing",
 429          1000, 0, 0)
 430
 431 /* The cost of expression in loop invariant motion that is considered
 432    expensive.  */
 433 DEFPARAM(PARAM_LIM_EXPENSIVE,
 434          "lim-expensive",
 435          "The minimum cost of an expensive expression in the loop invariant motion",
 436          20, 0, 0)
 437
 438 /* Bound on number of candidates for induction variables below that
 439    all candidates are considered for each use in induction variable
 440    optimizations.  */
 441
 442 DEFPARAM(PARAM_IV_CONSIDER_ALL_CANDIDATES_BOUND,
 443          "iv-consider-all-candidates-bound",
 444          "Bound on number of candidates below that all candidates are considered in iv optimizations",
 445          30, 0, 0)
 446
 447 /* The induction variable optimizations give up on loops that contain more
 448    induction variable uses.  */
 449
 450 DEFPARAM(PARAM_IV_MAX_CONSIDERED_USES,
 451          "iv-max-considered-uses",
 452          "Bound on number of iv uses in loop optimized in iv optimizations",
 453          250, 0, 0)
 454
 455 /* If there are at most this number of ivs in the set, try removing unnecessary
 456    ivs from the set always.  */
 457
 458 DEFPARAM(PARAM_IV_ALWAYS_PRUNE_CAND_SET_BOUND,
 459          "iv-always-prune-cand-set-bound",
 460          "If number of candidates in the set is smaller, we always try to remove unused ivs during its optimization",
 461          10, 0, 0)
 462
 463 DEFPARAM(PARAM_SCEV_MAX_EXPR_SIZE,
 464          "scev-max-expr-size",
 465          "Bound on size of expressions used in the scalar evolutions analyzer",
 466          20, 0, 0)
 467
 468 DEFPARAM(PARAM_OMEGA_MAX_VARS,
 469          "omega-max-vars",
 470          "Bound on the number of variables in Omega constraint systems",
 471          128, 0, 0)
 472
 473 DEFPARAM(PARAM_OMEGA_MAX_GEQS,
 474          "omega-max-geqs",
 475          "Bound on the number of inequalities in Omega constraint systems",
 476          256, 0, 0)
 477
 478 DEFPARAM(PARAM_OMEGA_MAX_EQS,
 479          "omega-max-eqs",
 480          "Bound on the number of equalities in Omega constraint systems",
 481          128, 0, 0)
 482
 483 DEFPARAM(PARAM_OMEGA_MAX_WILD_CARDS,
 484          "omega-max-wild-cards",
 485          "Bound on the number of wild cards in Omega constraint systems",
 486          18, 0, 0)
 487
 488 DEFPARAM(PARAM_OMEGA_HASH_TABLE_SIZE,
 489          "omega-hash-table-size",
 490          "Bound on the size of the hash table in Omega constraint systems",
 491          550, 0, 0)
 492
 493 DEFPARAM(PARAM_OMEGA_MAX_KEYS,
 494          "omega-max-keys",
 495          "Bound on the number of keys in Omega constraint systems",
 496          500, 0, 0)
 497
 498 DEFPARAM(PARAM_OMEGA_ELIMINATE_REDUNDANT_CONSTRAINTS,
 499          "omega-eliminate-redundant-constraints",
 500          "When set to 1, use expensive methods to eliminate all redundant constraints",
 501          0, 0, 1)
 502
 503 DEFPARAM(PARAM_VECT_MAX_VERSION_FOR_ALIGNMENT_CHECKS,
 504          "vect-max-version-for-alignment-checks",
 505          "Bound on number of runtime checks inserted by the vectorizer's loop versioning for alignment check",
 506          6, 0, 0)
 507
 508 DEFPARAM(PARAM_VECT_MAX_VERSION_FOR_ALIAS_CHECKS,
 509          "vect-max-version-for-alias-checks",
 510          "Bound on number of runtime checks inserted by the vectorizer's loop versioning for alias check",
 511          10, 0, 0)
 512
 513 DEFPARAM(PARAM_MAX_CSELIB_MEMORY_LOCATIONS,
 514          "max-cselib-memory-locations",
 515          "The maximum memory locations recorded by cselib",
 516          500, 0, 0)
 517 DEFPARAM(PARAM_MAX_FLOW_MEMORY_LOCATIONS,
 518          "max-flow-memory-locations",
 519          "The maximum memory locations recorded by flow",
 520          100, 0, 0)
 521
 522 #ifdef ENABLE_GC_ALWAYS_COLLECT
 523 # define GGC_MIN_EXPAND_DEFAULT 0
 524 # define GGC_MIN_HEAPSIZE_DEFAULT 0
 525 #else
 526 # define GGC_MIN_EXPAND_DEFAULT 30
 527 # define GGC_MIN_HEAPSIZE_DEFAULT 4096
 528 #endif
 529
 530 DEFPARAM(GGC_MIN_EXPAND,
 531          "ggc-min-expand",
 532          "Minimum heap expansion to trigger garbage collection, as a percentage of the total size of the heap",
 533          GGC_MIN_EXPAND_DEFAULT, 0, 0)
 534
 535 DEFPARAM(GGC_MIN_HEAPSIZE,
 536          "ggc-min-heapsize",
 537          "Minimum heap size before we start collecting garbage, in kilobytes",
 538          GGC_MIN_HEAPSIZE_DEFAULT, 0, 0)
 539
 540 #undef GGC_MIN_EXPAND_DEFAULT
 541 #undef GGC_MIN_HEAPSIZE_DEFAULT
 542
 543 DEFPARAM(PARAM_MAX_RELOAD_SEARCH_INSNS,
 544          "max-reload-search-insns",
 545          "The maximum number of instructions to search backward when looking for equivalent reload",
 546          100, 0, 0)
 547
 548 DEFPARAM(PARAM_MAX_ALIASED_VOPS,
 549          "max-aliased-vops",
 550          "The maximum number of virtual operators that a function is allowed to have before triggering memory partitioning heuristics",
 551          100, 0, 0)
 552
 553 DEFPARAM(PARAM_AVG_ALIASED_VOPS,
 554          "avg-aliased-vops",
 555          "The average number of virtual operators that memory statements are allowed to have before triggering memory partitioning heuristics",
 556          1, 0, 0)
 557
 558 DEFPARAM(PARAM_MAX_SCHED_REGION_BLOCKS,
 559          "max-sched-region-blocks",
 560          "The maximum number of blocks in a region to be considered for interblock scheduling",
 561          10, 0, 0)
 562
 563 DEFPARAM(PARAM_MAX_SCHED_REGION_INSNS,
 564          "max-sched-region-insns",
 565          "The maximum number of insns in a region to be considered for interblock scheduling",
 566          100, 0, 0)
 567
 568 DEFPARAM(PARAM_MIN_SPEC_PROB,
 569          "min-spec-prob",
 570          "The minimum probability of reaching a source block for interblock speculative scheduling",
 571          40, 0, 0)
 572
 573 DEFPARAM(PARAM_MAX_SCHED_EXTEND_REGIONS_ITERS,
 574          "max-sched-extend-regions-iters",
 575          "The maximum number of iterations through CFG to extend regions",
 576          0, 0, 0)
 577
 578 DEFPARAM(PARAM_MAX_SCHED_INSN_CONFLICT_DELAY,
 579          "max-sched-insn-conflict-delay",
 580          "The maximum conflict delay for an insn to be considered for speculative motion",
 581          3, 1, 10)
 582
 583 DEFPARAM(PARAM_SCHED_SPEC_PROB_CUTOFF,
 584          "sched-spec-prob-cutoff",
 585          "The minimal probability of speculation success (in percents), so that speculative insn will be scheduled.",
 586          40, 0, 100)
 587
 588 DEFPARAM(PARAM_MAX_LAST_VALUE_RTL,
 589          "max-last-value-rtl",
 590          "The maximum number of RTL nodes that can be recorded as combiner's last value",
 591          10000, 0, 0)
 592
 593 /* INTEGER_CST nodes are shared for values [{-1,0} .. N) for
 594    {signed,unsigned} integral types.  This determines N.
 595    Experimentation shows 256 to be a good value.  */
 596 DEFPARAM (PARAM_INTEGER_SHARE_LIMIT,
 597           "integer-share-limit",
 598           "The upper bound for sharing integer constants",
 599           256, 2, 2)
 600
 601 /* Incremental SSA updates for virtual operands may be very slow if
 602    there is a large number of mappings to process.  In those cases, it
 603    is faster to rewrite the virtual symbols from scratch as if they
 604    had been recently introduced.  This heuristic cannot be applied to
 605    SSA mappings for real SSA names, only symbols kept in FUD chains.
 606
 607    PARAM_MIN_VIRTUAL_MAPPINGS specifies the minimum number of virtual
 608    mappings that should be registered to trigger the heuristic.
 609
 610    PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO specifies the ratio between
 611    mappings and symbols.  If the number of virtual mappings is
 612    PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO bigger than the number of
 613    virtual symbols to be updated, then the updater switches to a full
 614    update for those symbols.  */
 615 DEFPARAM (PARAM_MIN_VIRTUAL_MAPPINGS,
 616           "min-virtual-mappings",
 617           "Minimum number of virtual mappings to consider switching to full virtual renames",
 618           100, 0, 0)
 619
 620 DEFPARAM (PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO,
 621           "virtual-mappings-ratio",
 622           "Ratio between virtual mappings and virtual symbols to do full virtual renames",
 623           3, 0, 0)
 624
 625 DEFPARAM (PARAM_SSP_BUFFER_SIZE,
 626           "ssp-buffer-size",
 627           "The lower bound for a buffer to be considered for stack smashing protection",
 628           8, 1, 0)
 629
 630 /* When we thread through a block we have to make copies of the
 631    statements within the block.  Clearly for large blocks the code
 632    duplication is bad.
 633
 634    PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS specifies the maximum number
 635    of statements and PHI nodes allowed in a block which is going to
 636    be duplicated for thread jumping purposes.
 637
 638    Some simple analysis showed that more than 99% of the jump
 639    threading opportunities are for blocks with less than 15
 640    statements.  So we can get the benefits of jump threading
 641    without excessive code bloat for pathological cases with the
 642    throttle set at 15 statements.  */
 643 DEFPARAM (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS,
 644           "max-jump-thread-duplication-stmts",
 645           "Maximum number of statements allowed in a block that needs to be duplicated when threading jumps",
 646           15, 0, 0)
 647
 648 /* This is the maximum number of fields a variable may have before the pointer analysis machinery
 649    will stop trying to treat it in a field-sensitive manner.
 650    There are programs out there with thousands of fields per structure, and handling them
 651    field-sensitively is not worth the cost.  */
 652 DEFPARAM (PARAM_MAX_FIELDS_FOR_FIELD_SENSITIVE,
 653           "max-fields-for-field-sensitive",
 654           "Maximum number of fields in a structure before pointer analysis treats the structure as a single variable",
 655           100, 0, 0)
 656
 657 DEFPARAM(PARAM_MAX_SCHED_READY_INSNS,
 658          "max-sched-ready-insns",
 659          "The maximum number of instructions ready to be issued to be considered by the scheduler during the first scheduling pass",
 660          100, 0, 0)
 661
 662 /* Prefetching and cache-optimizations related parameters.  Default values are
 663    usually set by machine description.  */
 664
 665 /* The number of insns executed before prefetch is completed.  */
 666
 667 DEFPARAM (PARAM_PREFETCH_LATENCY,
 668          "prefetch-latency",
 669          "The number of insns executed before prefetch is completed",
 670          200, 0, 0)
 671
 672 /* The number of prefetches that can run at the same time.  */
 673
 674 DEFPARAM (PARAM_SIMULTANEOUS_PREFETCHES,
 675           "simultaneous-prefetches",
 676           "The number of prefetches that can run at the same time",
 677           3, 0, 0)
 678
 679 /* The size of L1 cache in kB.  */
 680
 681 DEFPARAM (PARAM_L1_CACHE_SIZE,
 682           "l1-cache-size",
 683           "The size of L1 cache",
 684           64, 0, 0)
 685
 686 /* The size of L1 cache line in bytes.  */
 687
 688 DEFPARAM (PARAM_L1_CACHE_LINE_SIZE,
 689           "l1-cache-line-size",
 690           "The size of L1 cache line",
 691           32, 0, 0)
 692
 693 /* The size of L2 cache in kB.  */
 694
 695 DEFPARAM (PARAM_L2_CACHE_SIZE,
 696           "l2-cache-size",
 697           "The size of L2 cache",
 698           512, 0, 0)
 699
 700 /* Whether we should use canonical types rather than deep "structural"
 701    type checking.  Setting this value to 1 (the default) improves
 702    compilation performance in the C++ and Objective-C++ front end;
 703    this value should only be set to zero to work around bugs in the
 704    canonical type system by disabling it.  */
 705
 706 DEFPARAM (PARAM_USE_CANONICAL_TYPES,
 707           "use-canonical-types",
 708           "Whether to use canonical types",
 709           1, 0, 1)
 710
 711 DEFPARAM (PARAM_MAX_PARTIAL_ANTIC_LENGTH,
 712           "max-partial-antic-length",
 713           "Maximum length of partial antic set when performing tree pre optimization",
 714           100, 0, 0)
 715
 716 /* The following is used as a stop-gap limit for cases where really huge
 717    SCCs blow up memory and compile-time use too much.  If we hit this limit,
 718    SCCVN and such FRE and PRE will be not done at all for the current
 719    function.  */
 720
 721 DEFPARAM (PARAM_SCCVN_MAX_SCC_SIZE,
 722           "sccvn-max-scc-size",
 723           "Maximum size of a SCC before SCCVN stops processing a function",
 724           10000, 10, 0)
 725
 726
 727 DEFPARAM (PARAM_DF_DOUBLE_QUEUE_THRESHOLD_FACTOR,
 728           "df-double-queue-threshold-factor",
 729           "Multiplier used for determining the double-queueing threshold",
 730           2, 0, 0)
 731
 732 /*
 733 Local variables:
 734 mode:c
 735 End:
 736 */