gcc/params.def

   1 /* params.def - Run-time parameters.
   2    Copyright (C) 2001-2013 Free Software Foundation, Inc.
   3    Written by Mark Mitchell <mark@codesourcery.com>.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 /* This file contains definitions for language-independent
  22    parameters.  The DEFPARAM macro takes 6 arguments:
  23
  24      - The enumeral corresponding to this parameter.
  25
  26      - The name that can be used to set this parameter using the
  27        command-line option `--param <name>=<value>'.
  28
  29      - A help string explaining how the parameter is used.
  30
  31      - A default value for the parameter.
  32
  33      - The minimum acceptable value for the parameter.
  34
  35      - The maximum acceptable value for the parameter (if greater than
  36      the minimum).
  37
  38    Be sure to add an entry to invoke.texi summarizing the parameter.  */
  39
  40 /* When branch is predicted to be taken with probability lower than this
  41    threshold (in percent), then it is considered well predictable. */
  42 DEFPARAM (PARAM_PREDICTABLE_BRANCH_OUTCOME,
  43           "predictable-branch-outcome",
  44           "Maximal estimated outcome of branch considered predictable",
  45           2, 0, 50)
  46
  47 DEFPARAM (PARAM_INLINE_MIN_SPEEDUP,
  48           "inline-min-speedup",
  49           "The minimal estimated speedup allowing inliner to ignore inline-insns-single and inline-isnsns-auto",
  50           10, 0, 0)
  51
  52 /* The single function inlining limit. This is the maximum size
  53    of a function counted in internal gcc instructions (not in
  54    real machine instructions) that is eligible for inlining
  55    by the tree inliner.
  56    The default value is 450.
  57    Only functions marked inline (or methods defined in the class
  58    definition for C++) are affected by this.
  59    There are more restrictions to inlining: If inlined functions
  60    call other functions, the already inlined instructions are
  61    counted and once the recursive inline limit (see
  62    "max-inline-insns" parameter) is exceeded, the acceptable size
  63    gets decreased.  */
  64 DEFPARAM (PARAM_MAX_INLINE_INSNS_SINGLE,
  65           "max-inline-insns-single",
  66           "The maximum number of instructions in a single function eligible for inlining",
  67           400, 0, 0)
  68
  69 /* The single function inlining limit for functions that are
  70    inlined by virtue of -finline-functions (-O3).
  71    This limit should be chosen to be below or equal to the limit
  72    that is applied to functions marked inlined (or defined in the
  73    class declaration in C++) given by the "max-inline-insns-single"
  74    parameter.
  75    The default value is 40.  */
  76 DEFPARAM (PARAM_MAX_INLINE_INSNS_AUTO,
  77           "max-inline-insns-auto",
  78           "The maximum number of instructions when automatically inlining",
  79           40, 0, 0)
  80
  81 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE,
  82           "max-inline-insns-recursive",
  83           "The maximum number of instructions inline function can grow to via recursive inlining",
  84           450, 0, 0)
  85
  86 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE_AUTO,
  87           "max-inline-insns-recursive-auto",
  88           "The maximum number of instructions non-inline function can grow to via recursive inlining",
  89           450, 0, 0)
  90
  91 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH,
  92           "max-inline-recursive-depth",
  93           "The maximum depth of recursive inlining for inline functions",
  94           8, 0, 0)
  95
  96 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH_AUTO,
  97           "max-inline-recursive-depth-auto",
  98           "The maximum depth of recursive inlining for non-inline functions",
  99           8, 0, 0)
 100
 101 DEFPARAM (PARAM_MIN_INLINE_RECURSIVE_PROBABILITY,
 102           "min-inline-recursive-probability",
 103           "Inline recursively only when the probability of call being executed exceeds the parameter",
 104           10, 0, 0)
 105
 106 /* Limit of iterations of early inliner.  This basically bounds number of
 107    nested indirect calls early inliner can resolve.  Deeper chains are still
 108    handled by late inlining.  */
 109 DEFPARAM (PARAM_EARLY_INLINER_MAX_ITERATIONS,
 110           "max-early-inliner-iterations",
 111           "The maximum number of nested indirect inlining performed by early inliner",
 112           1, 0, 0)
 113
 114 /* Limit on probability of entry BB.  */
 115 DEFPARAM (PARAM_COMDAT_SHARING_PROBABILITY,
 116           "comdat-sharing-probability",
 117           "Probability that COMDAT function will be shared with different compilation unit",
 118           20, 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 /* This parameter limits the number of backtracking attempts when using the
 172    haifa scheduler for modulo scheduling.  */
 173 DEFPARAM(PARAM_MAX_MODULO_BACKTRACK_ATTEMPTS,
 174          "max-modulo-backtrack-attempts",
 175          "The maximum number of backtrack attempts the scheduler should make when modulo scheduling a loop",
 176          40, 0, 0)
 177
 178 DEFPARAM(PARAM_LARGE_FUNCTION_INSNS,
 179          "large-function-insns",
 180          "The size of function body to be considered large",
 181          2700, 0, 0)
 182 DEFPARAM(PARAM_LARGE_FUNCTION_GROWTH,
 183          "large-function-growth",
 184          "Maximal growth due to inlining of large function (in percent)",
 185          100, 0, 0)
 186 DEFPARAM(PARAM_LARGE_UNIT_INSNS,
 187          "large-unit-insns",
 188          "The size of translation unit to be considered large",
 189          10000, 0, 0)
 190 DEFPARAM(PARAM_INLINE_UNIT_GROWTH,
 191          "inline-unit-growth",
 192          "How much can given compilation unit grow because of the inlining (in percent)",
 193          30, 0, 0)
 194 DEFPARAM(PARAM_IPCP_UNIT_GROWTH,
 195          "ipcp-unit-growth",
 196          "How much can given compilation unit grow because of the interprocedural constant propagation (in percent)",
 197          10, 0, 0)
 198 DEFPARAM(PARAM_EARLY_INLINING_INSNS,
 199          "early-inlining-insns",
 200          "Maximal estimated growth of function body caused by early inlining of single call",
 201          11, 0, 0)
 202 DEFPARAM(PARAM_LARGE_STACK_FRAME,
 203          "large-stack-frame",
 204          "The size of stack frame to be considered large",
 205          256, 0, 0)
 206 DEFPARAM(PARAM_STACK_FRAME_GROWTH,
 207          "large-stack-frame-growth",
 208          "Maximal stack frame growth due to inlining (in percent)",
 209          1000, 0, 0)
 210
 211 /* The GCSE optimization will be disabled if it would require
 212    significantly more memory than this value.  */
 213 DEFPARAM(PARAM_MAX_GCSE_MEMORY,
 214          "max-gcse-memory",
 215          "The maximum amount of memory to be allocated by GCSE",
 216          50 * 1024 * 1024, 0, 0)
 217
 218 /* The GCSE optimization of an expression will avoided if the ratio of
 219    insertions to deletions is greater than this value.  */
 220 DEFPARAM(PARAM_MAX_GCSE_INSERTION_RATIO,
 221          "max-gcse-insertion-ratio",
 222          "The maximum ratio of insertions to deletions of expressions in GCSE",
 223          20, 0, 0)
 224
 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
 243 /* GCSE will use GCSE_COST_DISTANCE_RATION as a scaling factor
 244    to calculate maximum distance for which an expression is allowed to move
 245    from its rtx_cost.  */
 246 DEFPARAM(PARAM_GCSE_COST_DISTANCE_RATIO,
 247          "gcse-cost-distance-ratio",
 248          "Scaling factor in calculation of maximum distance an expression can be moved by GCSE optimizations",
 249          10, 0, 0)
 250 /* GCSE won't restrict distance for which an expression with rtx_cost greater
 251    than COSTS_N_INSN(GCSE_UNRESTRICTED_COST) is allowed to move.  */
 252 DEFPARAM(PARAM_GCSE_UNRESTRICTED_COST,
 253          "gcse-unrestricted-cost",
 254          "Cost at which GCSE optimizations will not constraint the distance an expression can travel",
 255          3, 0, 0)
 256
 257 /* How deep from a given basic block the dominator tree should be searched
 258    for expressions to hoist to the block.  The value of 0 will avoid limiting
 259    the search.  */
 260 DEFPARAM(PARAM_MAX_HOIST_DEPTH,
 261          "max-hoist-depth",
 262          "Maximum depth of search in the dominator tree for expressions to hoist",
 263          30, 0, 0)
 264
 265 /* This parameter limits the number of insns in a loop that will be unrolled,
 266    and by how much the loop is unrolled.
 267
 268    This limit should be at most half of the peeling limits:  loop unroller
 269    decides to not unroll loops that iterate fewer than 2*number of allowed
 270    unrollings and thus we would have loops that are neither peeled or unrolled
 271    otherwise.  */
 272 DEFPARAM(PARAM_MAX_UNROLLED_INSNS,
 273          "max-unrolled-insns",
 274          "The maximum number of instructions to consider to unroll in a loop",
 275          200, 0, 0)
 276 /* This parameter limits how many times the loop is unrolled depending
 277    on number of insns really executed in each iteration.  */
 278 DEFPARAM(PARAM_MAX_AVERAGE_UNROLLED_INSNS,
 279          "max-average-unrolled-insns",
 280          "The maximum number of instructions to consider to unroll in a loop on average",
 281          80, 0, 0)
 282 /* The maximum number of unrollings of a single loop.  */
 283 DEFPARAM(PARAM_MAX_UNROLL_TIMES,
 284         "max-unroll-times",
 285         "The maximum number of unrollings of a single loop",
 286         8, 0, 0)
 287 /* The maximum number of insns of a peeled loop.  */
 288 DEFPARAM(PARAM_MAX_PEELED_INSNS,
 289         "max-peeled-insns",
 290         "The maximum number of insns of a peeled loop",
 291         100, 0, 0)
 292 /* The maximum number of peelings of a single loop.  */
 293 DEFPARAM(PARAM_MAX_PEEL_TIMES,
 294         "max-peel-times",
 295         "The maximum number of peelings of a single loop",
 296         16, 0, 0)
 297 /* The maximum number of peelings of a single loop that is peeled completely.  */
 298 DEFPARAM(PARAM_MAX_PEEL_BRANCHES,
 299         "max-peel-branches",
 300         "The maximum number of branches on the path through the peeled sequence",
 301         32, 0, 0)
 302 /* The maximum number of insns of a peeled loop.  */
 303 DEFPARAM(PARAM_MAX_COMPLETELY_PEELED_INSNS,
 304         "max-completely-peeled-insns",
 305         "The maximum number of insns of a completely peeled loop",
 306         100, 0, 0)
 307 /* The maximum number of peelings of a single loop that is peeled completely.  */
 308 DEFPARAM(PARAM_MAX_COMPLETELY_PEEL_TIMES,
 309         "max-completely-peel-times",
 310         "The maximum number of peelings of a single loop that is peeled completely",
 311         16, 0, 0)
 312 /* The maximum number of insns of a peeled loop that rolls only once.  */
 313 DEFPARAM(PARAM_MAX_ONCE_PEELED_INSNS,
 314         "max-once-peeled-insns",
 315         "The maximum number of insns of a peeled loop that rolls only once",
 316         400, 0, 0)
 317 /* The maximum depth of a loop nest we completely peel.  */
 318 DEFPARAM(PARAM_MAX_UNROLL_ITERATIONS,
 319          "max-completely-peel-loop-nest-depth",
 320          "The maximum depth of a loop nest we completely peel",
 321          8, 0, 0)
 322
 323 /* The maximum number of insns of an unswitched loop.  */
 324 DEFPARAM(PARAM_MAX_UNSWITCH_INSNS,
 325         "max-unswitch-insns",
 326         "The maximum number of insns of an unswitched loop",
 327         50, 0, 0)
 328 /* The maximum level of recursion in unswitch_single_loop.  */
 329 DEFPARAM(PARAM_MAX_UNSWITCH_LEVEL,
 330         "max-unswitch-level",
 331         "The maximum number of unswitchings in a single loop",
 332         3, 0, 0)
 333
 334 /* The maximum number of iterations of a loop the brute force algorithm
 335    for analysis of # of iterations of the loop tries to evaluate.  */
 336 DEFPARAM(PARAM_MAX_ITERATIONS_TO_TRACK,
 337         "max-iterations-to-track",
 338         "Bound on the number of iterations the brute force # of iterations analysis algorithm evaluates",
 339         1000, 0, 0)
 340 /* A cutoff to avoid costly computations of the number of iterations in
 341    the doloop transformation.  */
 342 DEFPARAM(PARAM_MAX_ITERATIONS_COMPUTATION_COST,
 343         "max-iterations-computation-cost",
 344         "Bound on the cost of an expression to compute the number of iterations",
 345         10, 0, 0)
 346
 347 /* This parameter is used to tune SMS MAX II calculations.  */
 348 DEFPARAM(PARAM_SMS_MAX_II_FACTOR,
 349          "sms-max-ii-factor",
 350          "A factor for tuning the upper bound that swing modulo scheduler uses for scheduling a loop",
 351          100, 0, 0)
 352 /* The minimum value of stage count that swing modulo scheduler will generate.  */
 353 DEFPARAM(PARAM_SMS_MIN_SC,
 354         "sms-min-sc",
 355         "The minimum value of stage count that swing modulo scheduler will generate.",
 356         2, 1, 1)
 357 DEFPARAM(PARAM_SMS_DFA_HISTORY,
 358          "sms-dfa-history",
 359          "The number of cycles the swing modulo scheduler considers when checking conflicts using DFA",
 360          0, 0, 0)
 361 DEFPARAM(PARAM_SMS_LOOP_AVERAGE_COUNT_THRESHOLD,
 362          "sms-loop-average-count-threshold",
 363          "A threshold on the average loop count considered by the swing modulo scheduler",
 364          0, 0, 0)
 365
 366 DEFPARAM(HOT_BB_COUNT_WS_PERMILLE,
 367          "hot-bb-count-ws-permille",
 368          "A basic block profile count is considered hot if it contributes to "
 369          "the given permillage of the entire profiled execution",
 370          999, 0, 1000)
 371 DEFPARAM(HOT_BB_FREQUENCY_FRACTION,
 372          "hot-bb-frequency-fraction",
 373          "Select fraction of the maximal frequency of executions of basic block in function given basic block needs to have to be considered hot",
 374          1000, 0, 0)
 375
 376 DEFPARAM (PARAM_ALIGN_THRESHOLD,
 377           "align-threshold",
 378           "Select fraction of the maximal frequency of executions of basic block in function given basic block get alignment",
 379           100, 1, 0)
 380
 381 DEFPARAM (PARAM_ALIGN_LOOP_ITERATIONS,
 382           "align-loop-iterations",
 383           "Loops iterating at least selected number of iterations will get loop alignement.",
 384           4, 0, 0)
 385
 386 /* For guessed profiles, the loops having unknown number of iterations
 387    are predicted to iterate relatively few (10) times at average.
 388    For functions containing one loop with large known number of iterations
 389    and other loops having unbounded loops we would end up predicting all
 390    the other loops cold that is not usually the case.  So we need to artificially
 391    flatten the profile.
 392
 393    We need to cut the maximal predicted iterations to large enough iterations
 394    so the loop appears important, but safely within maximum hotness
 395    range.  */
 396
 397 DEFPARAM(PARAM_MAX_PREDICTED_ITERATIONS,
 398          "max-predicted-iterations",
 399          "The maximum number of loop iterations we predict statically",
 400          100, 0, 0)
 401 DEFPARAM(TRACER_DYNAMIC_COVERAGE_FEEDBACK,
 402          "tracer-dynamic-coverage-feedback",
 403          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is available",
 404          95, 0, 100)
 405 DEFPARAM(TRACER_DYNAMIC_COVERAGE,
 406          "tracer-dynamic-coverage",
 407          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is not available",
 408          75, 0, 100)
 409 DEFPARAM(TRACER_MAX_CODE_GROWTH,
 410          "tracer-max-code-growth",
 411          "Maximal code growth caused by tail duplication (in percent)",
 412          100, 0, 0)
 413 DEFPARAM(TRACER_MIN_BRANCH_RATIO,
 414          "tracer-min-branch-ratio",
 415          "Stop reverse growth if the reverse probability of best edge is less than this threshold (in percent)",
 416          10, 0, 100)
 417 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK,
 418          "tracer-min-branch-probability-feedback",
 419          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is available",
 420          80, 0, 100)
 421 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY,
 422          "tracer-min-branch-probability",
 423          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is not available",
 424          50, 0, 100)
 425
 426 /* The maximum number of incoming edges to consider for crossjumping.  */
 427 DEFPARAM(PARAM_MAX_CROSSJUMP_EDGES,
 428          "max-crossjump-edges",
 429          "The maximum number of incoming edges to consider for crossjumping",
 430          100, 0, 0)
 431
 432 /* The minimum number of matching instructions to consider for crossjumping.  */
 433 DEFPARAM(PARAM_MIN_CROSSJUMP_INSNS,
 434      "min-crossjump-insns",
 435      "The minimum number of matching instructions to consider for crossjumping",
 436      5, 1, 0)
 437
 438 /* The maximum number expansion factor when copying basic blocks.  */
 439 DEFPARAM(PARAM_MAX_GROW_COPY_BB_INSNS,
 440      "max-grow-copy-bb-insns",
 441      "The maximum expansion factor when copying basic blocks",
 442      8, 0, 0)
 443
 444 /* The maximum number of insns to duplicate when unfactoring computed gotos.  */
 445 DEFPARAM(PARAM_MAX_GOTO_DUPLICATION_INSNS,
 446      "max-goto-duplication-insns",
 447      "The maximum number of insns to duplicate when unfactoring computed gotos",
 448      8, 0, 0)
 449
 450 /* The maximum length of path considered in cse.  */
 451 DEFPARAM(PARAM_MAX_CSE_PATH_LENGTH,
 452          "max-cse-path-length",
 453          "The maximum length of path considered in cse",
 454          10, 1, 0)
 455 DEFPARAM(PARAM_MAX_CSE_INSNS,
 456          "max-cse-insns",
 457          "The maximum instructions CSE process before flushing",
 458          1000, 0, 0)
 459
 460 /* The cost of expression in loop invariant motion that is considered
 461    expensive.  */
 462 DEFPARAM(PARAM_LIM_EXPENSIVE,
 463          "lim-expensive",
 464          "The minimum cost of an expensive expression in the loop invariant motion",
 465          20, 0, 0)
 466
 467 /* Bound on number of candidates for induction variables below that
 468    all candidates are considered for each use in induction variable
 469    optimizations.  */
 470
 471 DEFPARAM(PARAM_IV_CONSIDER_ALL_CANDIDATES_BOUND,
 472          "iv-consider-all-candidates-bound",
 473          "Bound on number of candidates below that all candidates are considered in iv optimizations",
 474          30, 0, 0)
 475
 476 /* The induction variable optimizations give up on loops that contain more
 477    induction variable uses.  */
 478
 479 DEFPARAM(PARAM_IV_MAX_CONSIDERED_USES,
 480          "iv-max-considered-uses",
 481          "Bound on number of iv uses in loop optimized in iv optimizations",
 482          250, 0, 0)
 483
 484 /* If there are at most this number of ivs in the set, try removing unnecessary
 485    ivs from the set always.  */
 486
 487 DEFPARAM(PARAM_IV_ALWAYS_PRUNE_CAND_SET_BOUND,
 488          "iv-always-prune-cand-set-bound",
 489          "If number of candidates in the set is smaller, we always try to remove unused ivs during its optimization",
 490          10, 0, 0)
 491
 492 DEFPARAM(PARAM_SCEV_MAX_EXPR_SIZE,
 493          "scev-max-expr-size",
 494          "Bound on size of expressions used in the scalar evolutions analyzer",
 495          100, 0, 0)
 496
 497 DEFPARAM(PARAM_SCEV_MAX_EXPR_COMPLEXITY,
 498          "scev-max-expr-complexity",
 499          "Bound on the complexity of the expressions in the scalar evolutions analyzer",
 500          10, 0, 0)
 501
 502 DEFPARAM(PARAM_OMEGA_MAX_VARS,
 503          "omega-max-vars",
 504          "Bound on the number of variables in Omega constraint systems",
 505          128, 0, 0)
 506
 507 DEFPARAM(PARAM_OMEGA_MAX_GEQS,
 508          "omega-max-geqs",
 509          "Bound on the number of inequalities in Omega constraint systems",
 510          256, 0, 0)
 511
 512 DEFPARAM(PARAM_OMEGA_MAX_EQS,
 513          "omega-max-eqs",
 514          "Bound on the number of equalities in Omega constraint systems",
 515          128, 0, 0)
 516
 517 DEFPARAM(PARAM_OMEGA_MAX_WILD_CARDS,
 518          "omega-max-wild-cards",
 519          "Bound on the number of wild cards in Omega constraint systems",
 520          18, 0, 0)
 521
 522 DEFPARAM(PARAM_OMEGA_HASH_TABLE_SIZE,
 523          "omega-hash-table-size",
 524          "Bound on the size of the hash table in Omega constraint systems",
 525          550, 0, 0)
 526
 527 DEFPARAM(PARAM_OMEGA_MAX_KEYS,
 528          "omega-max-keys",
 529          "Bound on the number of keys in Omega constraint systems",
 530          500, 0, 0)
 531
 532 DEFPARAM(PARAM_OMEGA_ELIMINATE_REDUNDANT_CONSTRAINTS,
 533          "omega-eliminate-redundant-constraints",
 534          "When set to 1, use expensive methods to eliminate all redundant constraints",
 535          0, 0, 1)
 536
 537 DEFPARAM(PARAM_VECT_MAX_VERSION_FOR_ALIGNMENT_CHECKS,
 538          "vect-max-version-for-alignment-checks",
 539          "Bound on number of runtime checks inserted by the vectorizer's loop versioning for alignment check",
 540          6, 0, 0)
 541
 542 DEFPARAM(PARAM_VECT_MAX_VERSION_FOR_ALIAS_CHECKS,
 543          "vect-max-version-for-alias-checks",
 544          "Bound on number of runtime checks inserted by the vectorizer's loop versioning for alias check",
 545          10, 0, 0)
 546
 547 DEFPARAM(PARAM_MAX_CSELIB_MEMORY_LOCATIONS,
 548          "max-cselib-memory-locations",
 549          "The maximum memory locations recorded by cselib",
 550          500, 0, 0)
 551
 552 #ifdef ENABLE_GC_ALWAYS_COLLECT
 553 # define GGC_MIN_EXPAND_DEFAULT 0
 554 # define GGC_MIN_HEAPSIZE_DEFAULT 0
 555 #else
 556 # define GGC_MIN_EXPAND_DEFAULT 30
 557 # define GGC_MIN_HEAPSIZE_DEFAULT 4096
 558 #endif
 559
 560 DEFPARAM(GGC_MIN_EXPAND,
 561          "ggc-min-expand",
 562          "Minimum heap expansion to trigger garbage collection, as a percentage of the total size of the heap",
 563          GGC_MIN_EXPAND_DEFAULT, 0, 0)
 564
 565 DEFPARAM(GGC_MIN_HEAPSIZE,
 566          "ggc-min-heapsize",
 567          "Minimum heap size before we start collecting garbage, in kilobytes",
 568          GGC_MIN_HEAPSIZE_DEFAULT, 0, 0)
 569
 570 #undef GGC_MIN_EXPAND_DEFAULT
 571 #undef GGC_MIN_HEAPSIZE_DEFAULT
 572
 573 DEFPARAM(PARAM_MAX_RELOAD_SEARCH_INSNS,
 574          "max-reload-search-insns",
 575          "The maximum number of instructions to search backward when looking for equivalent reload",
 576          100, 0, 0)
 577
 578 DEFPARAM(PARAM_SINK_FREQUENCY_THRESHOLD,
 579          "sink-frequency-threshold",
 580          "Target block's relative execution frequency (as a percentage) required to sink a statement",
 581          75, 0, 100)
 582
 583 DEFPARAM(PARAM_MAX_SCHED_REGION_BLOCKS,
 584          "max-sched-region-blocks",
 585          "The maximum number of blocks in a region to be considered for interblock scheduling",
 586          10, 0, 0)
 587
 588 DEFPARAM(PARAM_MAX_SCHED_REGION_INSNS,
 589          "max-sched-region-insns",
 590          "The maximum number of insns in a region to be considered for interblock scheduling",
 591          100, 0, 0)
 592
 593 DEFPARAM(PARAM_MAX_PIPELINE_REGION_BLOCKS,
 594          "max-pipeline-region-blocks",
 595          "The maximum number of blocks in a region to be considered for interblock scheduling",
 596          15, 0, 0)
 597
 598 DEFPARAM(PARAM_MAX_PIPELINE_REGION_INSNS,
 599          "max-pipeline-region-insns",
 600          "The maximum number of insns in a region to be considered for interblock scheduling",
 601          200, 0, 0)
 602
 603 DEFPARAM(PARAM_MIN_SPEC_PROB,
 604          "min-spec-prob",
 605          "The minimum probability of reaching a source block for interblock speculative scheduling",
 606          40, 0, 0)
 607
 608 DEFPARAM(PARAM_MAX_SCHED_EXTEND_REGIONS_ITERS,
 609          "max-sched-extend-regions-iters",
 610          "The maximum number of iterations through CFG to extend regions",
 611          0, 0, 0)
 612
 613 DEFPARAM(PARAM_MAX_SCHED_INSN_CONFLICT_DELAY,
 614          "max-sched-insn-conflict-delay",
 615          "The maximum conflict delay for an insn to be considered for speculative motion",
 616          3, 1, 10)
 617
 618 DEFPARAM(PARAM_SCHED_SPEC_PROB_CUTOFF,
 619          "sched-spec-prob-cutoff",
 620          "The minimal probability of speculation success (in percents), so that speculative insn will be scheduled.",
 621          40, 0, 100)
 622
 623 DEFPARAM(PARAM_SCHED_STATE_EDGE_PROB_CUTOFF,
 624          "sched-state-edge-prob-cutoff",
 625          "The minimum probability an edge must have for the scheduler to save its state across it.",
 626          10, 0, 100)
 627
 628 DEFPARAM(PARAM_SELSCHED_MAX_LOOKAHEAD,
 629          "selsched-max-lookahead",
 630          "The maximum size of the lookahead window of selective scheduling",
 631          50, 0, 0)
 632
 633 DEFPARAM(PARAM_SELSCHED_MAX_SCHED_TIMES,
 634          "selsched-max-sched-times",
 635          "Maximum number of times that an insn could be scheduled",
 636          2, 0, 0)
 637
 638 DEFPARAM(PARAM_SELSCHED_INSNS_TO_RENAME,
 639          "selsched-insns-to-rename",
 640          "Maximum number of instructions in the ready list that are considered eligible for renaming",
 641          2, 0, 0)
 642
 643 DEFPARAM (PARAM_SCHED_MEM_TRUE_DEP_COST,
 644           "sched-mem-true-dep-cost",
 645           "Minimal distance between possibly conflicting store and load",
 646           1, 0, 0)
 647
 648 DEFPARAM(PARAM_MAX_LAST_VALUE_RTL,
 649          "max-last-value-rtl",
 650          "The maximum number of RTL nodes that can be recorded as combiner's last value",
 651          10000, 0, 0)
 652
 653 /* INTEGER_CST nodes are shared for values [{-1,0} .. N) for
 654    {signed,unsigned} integral types.  This determines N.
 655    Experimentation shows 251 to be a good value that generates the
 656    least amount of garbage for allocating the TREE_VEC storage.  */
 657 DEFPARAM (PARAM_INTEGER_SHARE_LIMIT,
 658           "integer-share-limit",
 659           "The upper bound for sharing integer constants",
 660           251, 2, 2)
 661
 662 DEFPARAM (PARAM_SSP_BUFFER_SIZE,
 663           "ssp-buffer-size",
 664           "The lower bound for a buffer to be considered for stack smashing protection",
 665           8, 1, 0)
 666
 667 /* When we thread through a block we have to make copies of the
 668    statements within the block.  Clearly for large blocks the code
 669    duplication is bad.
 670
 671    PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS specifies the maximum number
 672    of statements and PHI nodes allowed in a block which is going to
 673    be duplicated for thread jumping purposes.
 674
 675    Some simple analysis showed that more than 99% of the jump
 676    threading opportunities are for blocks with less than 15
 677    statements.  So we can get the benefits of jump threading
 678    without excessive code bloat for pathological cases with the
 679    throttle set at 15 statements.  */
 680 DEFPARAM (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS,
 681           "max-jump-thread-duplication-stmts",
 682           "Maximum number of statements allowed in a block that needs to be duplicated when threading jumps",
 683           15, 0, 0)
 684
 685 /* This is the maximum number of fields a variable may have before the pointer analysis machinery
 686    will stop trying to treat it in a field-sensitive manner.
 687    There are programs out there with thousands of fields per structure, and handling them
 688    field-sensitively is not worth the cost.  */
 689 DEFPARAM (PARAM_MAX_FIELDS_FOR_FIELD_SENSITIVE,
 690           "max-fields-for-field-sensitive",
 691           "Maximum number of fields in a structure before pointer analysis treats the structure as a single variable",
 692           0, 0, 0)
 693
 694 DEFPARAM(PARAM_MAX_SCHED_READY_INSNS,
 695          "max-sched-ready-insns",
 696          "The maximum number of instructions ready to be issued to be considered by the scheduler during the first scheduling pass",
 697          100, 0, 0)
 698
 699 /* This is the maximum number of active local stores RTL DSE will consider.  */
 700 DEFPARAM (PARAM_MAX_DSE_ACTIVE_LOCAL_STORES,
 701           "max-dse-active-local-stores",
 702           "Maximum number of active local stores in RTL dead store elimination",
 703           5000, 0, 0)
 704
 705 /* Prefetching and cache-optimizations related parameters.  Default values are
 706    usually set by machine description.  */
 707
 708 /* The number of insns executed before prefetch is completed.  */
 709
 710 DEFPARAM (PARAM_PREFETCH_LATENCY,
 711          "prefetch-latency",
 712          "The number of insns executed before prefetch is completed",
 713          200, 0, 0)
 714
 715 /* The number of prefetches that can run at the same time.  */
 716
 717 DEFPARAM (PARAM_SIMULTANEOUS_PREFETCHES,
 718           "simultaneous-prefetches",
 719           "The number of prefetches that can run at the same time",
 720           3, 0, 0)
 721
 722 /* The size of L1 cache in kB.  */
 723
 724 DEFPARAM (PARAM_L1_CACHE_SIZE,
 725           "l1-cache-size",
 726           "The size of L1 cache",
 727           64, 0, 0)
 728
 729 /* The size of L1 cache line in bytes.  */
 730
 731 DEFPARAM (PARAM_L1_CACHE_LINE_SIZE,
 732           "l1-cache-line-size",
 733           "The size of L1 cache line",
 734           32, 0, 0)
 735
 736 /* The size of L2 cache in kB.  */
 737
 738 DEFPARAM (PARAM_L2_CACHE_SIZE,
 739           "l2-cache-size",
 740           "The size of L2 cache",
 741           512, 0, 0)
 742
 743 /* Whether we should use canonical types rather than deep "structural"
 744    type checking.  Setting this value to 1 (the default) improves
 745    compilation performance in the C++ and Objective-C++ front end;
 746    this value should only be set to zero to work around bugs in the
 747    canonical type system by disabling it.  */
 748
 749 DEFPARAM (PARAM_USE_CANONICAL_TYPES,
 750           "use-canonical-types",
 751           "Whether to use canonical types",
 752           1, 0, 1)
 753
 754 DEFPARAM (PARAM_MAX_PARTIAL_ANTIC_LENGTH,
 755           "max-partial-antic-length",
 756           "Maximum length of partial antic set when performing tree pre optimization",
 757           100, 0, 0)
 758
 759 /* The following is used as a stop-gap limit for cases where really huge
 760    SCCs blow up memory and compile-time use too much.  If we hit this limit,
 761    SCCVN and such FRE and PRE will be not done at all for the current
 762    function.  */
 763
 764 DEFPARAM (PARAM_SCCVN_MAX_SCC_SIZE,
 765           "sccvn-max-scc-size",
 766           "Maximum size of a SCC before SCCVN stops processing a function",
 767           10000, 10, 0)
 768
 769 /* The following is used as a stop-gap limit for cases where really huge
 770    functions blow up compile-time use too much.  It limits the number of
 771    alias-queries we do for finding common subexpressions for memory loads and
 772    stores.  The number of alias-queries is otherwise limited by the number of
 773    stores on paths to function entry.  */
 774
 775 DEFPARAM (PARAM_SCCVN_MAX_ALIAS_QUERIES_PER_ACCESS,
 776           "sccvn-max-alias-queries-per-access",
 777           "Maximum number of disambiguations to perform per memory access",
 778           1000, 0, 0)
 779
 780 DEFPARAM (PARAM_IRA_MAX_LOOPS_NUM,
 781           "ira-max-loops-num",
 782           "Max loops number for regional RA",
 783           100, 0, 0)
 784
 785 DEFPARAM (PARAM_IRA_MAX_CONFLICT_TABLE_SIZE,
 786           "ira-max-conflict-table-size",
 787           "Max size of conflict table in MB",
 788           1000, 0, 0)
 789
 790 DEFPARAM (PARAM_IRA_LOOP_RESERVED_REGS,
 791           "ira-loop-reserved-regs",
 792           "The number of registers in each class kept unused by loop invariant motion",
 793           2, 0, 0)
 794
 795 /* Switch initialization conversion will refuse to create arrays that are
 796    bigger than this parameter times the number of switch branches.  */
 797
 798 DEFPARAM (PARAM_SWITCH_CONVERSION_BRANCH_RATIO,
 799           "switch-conversion-max-branch-ratio",
 800           "The maximum ratio between array size and switch branches for "
 801           "a switch conversion to take place",
 802           8, 1, 0)
 803
 804 /* Size of tiles when doing loop blocking.  */
 805
 806 DEFPARAM (PARAM_LOOP_BLOCK_TILE_SIZE,
 807           "loop-block-tile-size",
 808           "size of tiles for loop blocking",
 809           51, 0, 0)
 810
 811 /* Maximal number of parameters that we allow in a SCoP.  */
 812
 813 DEFPARAM (PARAM_GRAPHITE_MAX_NB_SCOP_PARAMS,
 814           "graphite-max-nb-scop-params",
 815           "maximum number of parameters in a SCoP",
 816           10, 0, 0)
 817
 818 /* Maximal number of basic blocks in the functions analyzed by Graphite.  */
 819
 820 DEFPARAM (PARAM_GRAPHITE_MAX_BBS_PER_FUNCTION,
 821           "graphite-max-bbs-per-function",
 822           "maximum number of basic blocks per function to be analyzed by Graphite",
 823           100, 0, 0)
 824
 825 /* Avoid data dependence analysis on very large loops.  */
 826 DEFPARAM (PARAM_LOOP_MAX_DATAREFS_FOR_DATADEPS,
 827           "loop-max-datarefs-for-datadeps",
 828           "Maximum number of datarefs in loop for building loop data dependencies",
 829           1000, 0, 0)
 830
 831 /* Avoid doing loop invariant motion on very large loops.  */
 832
 833 DEFPARAM (PARAM_LOOP_INVARIANT_MAX_BBS_IN_LOOP,
 834           "loop-invariant-max-bbs-in-loop",
 835           "Max basic blocks number in loop for loop invariant motion",
 836           10000, 0, 0)
 837
 838 /* Avoid SLP vectorization of large basic blocks.  */
 839 DEFPARAM (PARAM_SLP_MAX_INSNS_IN_BB,
 840           "slp-max-insns-in-bb",
 841           "Maximum number of instructions in basic block to be considered for SLP vectorization",
 842           1000, 0, 0)
 843
 844 DEFPARAM (PARAM_MIN_INSN_TO_PREFETCH_RATIO,
 845           "min-insn-to-prefetch-ratio",
 846           "Min. ratio of insns to prefetches to enable prefetching for "
 847           "a loop with an unknown trip count",
 848           9, 0, 0)
 849
 850 DEFPARAM (PARAM_PREFETCH_MIN_INSN_TO_MEM_RATIO,
 851           "prefetch-min-insn-to-mem-ratio",
 852           "Min. ratio of insns to mem ops to enable prefetching in a loop",
 853           3, 0, 0)
 854
 855 /* Set maximum hash table size for var tracking.  */
 856
 857 DEFPARAM (PARAM_MAX_VARTRACK_SIZE,
 858           "max-vartrack-size",
 859           "Max. size of var tracking hash tables",
 860           50000000, 0, 0)
 861
 862 /* Set maximum recursion depth for var tracking expression expansion
 863    and resolution.  */
 864
 865 DEFPARAM (PARAM_MAX_VARTRACK_EXPR_DEPTH,
 866           "max-vartrack-expr-depth",
 867           "Max. recursion depth for expanding var tracking expressions",
 868           12, 0, 0)
 869
 870 /* Set maximum length of value location list for which var tracking
 871    should add reverse operations.  */
 872
 873 DEFPARAM (PARAM_MAX_VARTRACK_REVERSE_OP_SIZE,
 874           "max-vartrack-reverse-op-size",
 875           "Max. size of loc list for which reverse ops should be added",
 876           50, 0, 0)
 877
 878 /* Set minimum insn uid for non-debug insns.  */
 879
 880 DEFPARAM (PARAM_MIN_NONDEBUG_INSN_UID,
 881           "min-nondebug-insn-uid",
 882           "The minimum UID to be used for a nondebug insn",
 883           0, 1, 0)
 884
 885 DEFPARAM (PARAM_IPA_SRA_PTR_GROWTH_FACTOR,
 886           "ipa-sra-ptr-growth-factor",
 887           "Maximum allowed growth of size of new parameters ipa-sra replaces "
 888           "a pointer to an aggregate with",
 889           2, 0, 0)
 890
 891 DEFPARAM (PARAM_TM_MAX_AGGREGATE_SIZE,
 892           "tm-max-aggregate-size",
 893           "Size in bytes after which thread-local aggregates should be "
 894           "instrumented with the logging functions instead of save/restore "
 895           "pairs",
 896           9, 0, 0)
 897
 898 DEFPARAM (PARAM_IPA_CP_VALUE_LIST_SIZE,
 899           "ipa-cp-value-list-size",
 900           "Maximum size of a list of values associated with each parameter for "
 901           "interprocedural constant propagation",
 902           8, 0, 0)
 903
 904 DEFPARAM (PARAM_IPA_CP_EVAL_THRESHOLD,
 905           "ipa-cp-eval-threshold",
 906           "Threshold ipa-cp opportunity evaluation that is still considered "
 907           "beneficial to clone.",
 908           500, 0, 0)
 909
 910 DEFPARAM (PARAM_IPA_MAX_AGG_ITEMS,
 911           "ipa-max-agg-items",
 912           "Maximum number of aggregate content items for a parameter in "
 913           "jump functions and lattices",
 914           16, 0, 0)
 915
 916 DEFPARAM (PARAM_IPA_CP_LOOP_HINT_BONUS,
 917           "ipa-cp-loop-hint-bonus",
 918           "Compile-time bonus IPA-CP assigns to candidates which make loop "
 919           "bounds or strides known.",
 920           64, 0, 0)
 921
 922 DEFPARAM (PARAM_IPA_CP_ARRAY_INDEX_HINT_BONUS,
 923           "ipa-cp-array-index-hint-bonus",
 924           "Compile-time bonus IPA-CP assigns to candidates which make an array "
 925           "index known.",
 926           48, 0, 0)
 927
 928 /* WHOPR partitioning configuration.  */
 929
 930 DEFPARAM (PARAM_LTO_PARTITIONS,
 931           "lto-partitions",
 932           "Number of partitions the program should be split to",
 933           32, 1, 0)
 934
 935 DEFPARAM (MIN_PARTITION_SIZE,
 936           "lto-min-partition",
 937           "Minimal size of a partition for LTO (in estimated instructions)",
 938           1000, 0, 0)
 939
 940 /* Diagnostic parameters.  */
 941
 942 DEFPARAM (CXX_MAX_NAMESPACES_FOR_DIAGNOSTIC_HELP,
 943           "cxx-max-namespaces-for-diagnostic-help",
 944           "Maximum number of namespaces to search for alternatives when "
 945           "name lookup fails",
 946           1000, 0, 0)
 947
 948 /* Maximum number of conditional store pairs that can be sunk.  */
 949 DEFPARAM (PARAM_MAX_STORES_TO_SINK,
 950           "max-stores-to-sink",
 951           "Maximum number of conditional store pairs that can be sunk",
 952           2, 0, 0)
 953
 954 /* Override CASE_VALUES_THRESHOLD of when to switch from doing switch
 955    statements via if statements to using a table jump operation.  If the value
 956    is 0, the default CASE_VALUES_THRESHOLD will be used.  */
 957 DEFPARAM (PARAM_CASE_VALUES_THRESHOLD,
 958           "case-values-threshold",
 959           "The smallest number of different values for which it is best to "
 960           "use a jump-table instead of a tree of conditional branches, "
 961           "if 0, use the default for the machine",
 962           0, 0, 0)
 963
 964 /* Data race flags for C++0x memory model compliance.  */
 965 DEFPARAM (PARAM_ALLOW_LOAD_DATA_RACES,
 966           "allow-load-data-races",
 967           "Allow new data races on loads to be introduced",
 968           1, 0, 1)
 969
 970 DEFPARAM (PARAM_ALLOW_STORE_DATA_RACES,
 971           "allow-store-data-races",
 972           "Allow new data races on stores to be introduced",
 973           1, 0, 1)
 974
 975 DEFPARAM (PARAM_ALLOW_PACKED_LOAD_DATA_RACES,
 976           "allow-packed-load-data-races",
 977           "Allow new data races on packed data loads to be introduced",
 978           1, 0, 1)
 979
 980 DEFPARAM (PARAM_ALLOW_PACKED_STORE_DATA_RACES,
 981           "allow-packed-store-data-races",
 982           "Allow new data races on packed data stores to be introduced",
 983           1, 0, 1)
 984
 985 /* Reassociation width to be used by tree reassoc optimization.  */
 986 DEFPARAM (PARAM_TREE_REASSOC_WIDTH,
 987           "tree-reassoc-width",
 988           "Set the maximum number of instructions executed in parallel in "
 989           "reassociated tree. If 0, use the target dependent heuristic.",
 990           0, 0, 0)
 991
 992 DEFPARAM (PARAM_MAX_TAIL_MERGE_COMPARISONS,
 993           "max-tail-merge-comparisons",
 994           "Maximum amount of similar bbs to compare a bb with",
 995           10, 0, 0)
 996
 997 DEFPARAM (PARAM_MAX_TAIL_MERGE_ITERATIONS,
 998           "max-tail-merge-iterations",
 999           "Maximum amount of iterations of the pass over a function",
1000           2, 0, 0)
1001
1002 /* Maximum number of strings for which strlen optimization pass will
1003    track string lenths.  */
1004 DEFPARAM (PARAM_MAX_TRACKED_STRLENS,
1005           "max-tracked-strlens",
1006           "Maximum number of strings for which strlen optimization pass will "
1007           "track string lengths",
1008           1000, 0, 0)
1009
1010 /* Keep this in sync with the sched_pressure_algorithm enum.  */
1011 DEFPARAM (PARAM_SCHED_PRESSURE_ALGORITHM,
1012           "sched-pressure-algorithm",
1013           "Which -fsched-pressure algorithm to apply",
1014           1, 1, 2)
1015
1016 /* Maximum length of candidate scans in straight-line strength reduction.  */
1017 DEFPARAM (PARAM_MAX_SLSR_CANDIDATE_SCAN,
1018           "max-slsr-cand-scan",
1019           "Maximum length of candidate scans for straight-line "
1020           "strength reduction",
1021           50, 1, 999999)
1022
1023 /*
1024 Local variables:
1025 mode:c
1026 End:
1027 */