gcc/params.def

   1 /* params.def - Run-time parameters.
   2    Copyright (C) 2001, 2002, 2004, 2005 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 2, 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 COPYING.  If not, write to the Free
  19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  20 02110-1301, USA.
  21
  22 */
  23
  24 /* This file contains definitions for language-independent
  25    parameters.  The DEFPARAM macro takes 6 arguments:
  26
  27      - The enumeral corresponding to this parameter.
  28
  29      - The name that can be used to set this parameter using the
  30        command-line option `--param <name>=<value>'.
  31
  32      - A help string explaining how the parameter is used.
  33
  34      - A default value for the parameter.
  35
  36      - The minimum acceptable value for the parameter.
  37
  38      - The maximum acceptable value for the parameter (if greater than
  39      the minimum).
  40
  41    Be sure to add an entry to invoke.texi summarizing the parameter.  */
  42
  43 /* The maximum number of fields in a variable with only implicit uses
  44    for which structure aliasing will consider trying to track each
  45    field.  The default is 5.  */
  46 DEFPARAM (PARAM_SALIAS_MAX_IMPLICIT_FIELDS,
  47           "salias-max-implicit-fields",
  48           "The maximum number of fields in a structure variable without direct structure accesses that GCC will attempt to track separately",
  49           5, 0, 0)
  50
  51 /* The maximum number of array elements structure aliasing will decompose
  52    an array for.  The default is 4.  */
  53 DEFPARAM (PARAM_SALIAS_MAX_ARRAY_ELEMENTS,
  54           "salias-max-array-elements",
  55           "The maximum number of elements in an array for wich we track its elements separately",
  56           4, 0, 0)
  57
  58 /* The maximum structure size at which the scalar replacement of
  59    aggregates (SRA) pass will perform block copies.  The default
  60    value, 0, implies that GCC will select the most appropriate size
  61    itself.  */
  62 DEFPARAM (PARAM_SRA_MAX_STRUCTURE_SIZE,
  63           "sra-max-structure-size",
  64           "The maximum structure size (in bytes) for which GCC will "
  65           "use by-element copies",
  66           0, 0, 0)
  67
  68 /* The maximum number of structure fields which the SRA pass will
  69    instantiate to avoid block copies.  The default value, 0, implies
  70    that GCC will select the appropriate value itself.  */
  71 DEFPARAM (PARAM_SRA_MAX_STRUCTURE_COUNT,
  72           "sra-max-structure-count",
  73           "The maximum number of structure fields for which GCC will "
  74           "use by-element copies",
  75           0, 0, 0)
  76
  77 /* The ratio between instantiated fields and the complete structure
  78    size.  We say that if the ratio of the number of bytes in
  79    instantiated fields to the number of bytes in the complete
  80    structure exceeds this parameter, or if the number of instantiated
  81    fields to the total number of fields exceeds this parameter, then
  82    block copies are not used.  The default is 75%.  */
  83 DEFPARAM (PARAM_SRA_FIELD_STRUCTURE_RATIO,
  84           "sra-field-structure-ratio",
  85           "The threshold ratio between instantiated fields and the total structure size",
  86           75, 0, 100)
  87
  88 /* The single function inlining limit. This is the maximum size
  89    of a function counted in internal gcc instructions (not in
  90    real machine instructions) that is eligible for inlining
  91    by the tree inliner.
  92    The default value is 450.
  93    Only functions marked inline (or methods defined in the class
  94    definition for C++) are affected by this.
  95    There are more restrictions to inlining: If inlined functions
  96    call other functions, the already inlined instructions are
  97    counted and once the recursive inline limit (see
  98    "max-inline-insns" parameter) is exceeded, the acceptable size
  99    gets decreased.  */
 100 DEFPARAM (PARAM_MAX_INLINE_INSNS_SINGLE,
 101           "max-inline-insns-single",
 102           "The maximum number of instructions in a single function eligible for inlining",
 103           450, 0, 0)
 104
 105 /* The single function inlining limit for functions that are
 106    inlined by virtue of -finline-functions (-O3).
 107    This limit should be chosen to be below or equal to the limit
 108    that is applied to functions marked inlined (or defined in the
 109    class declaration in C++) given by the "max-inline-insns-single"
 110    parameter.
 111    The default value is 90.  */
 112 DEFPARAM (PARAM_MAX_INLINE_INSNS_AUTO,
 113           "max-inline-insns-auto",
 114           "The maximum number of instructions when automatically inlining",
 115           90, 0, 0)
 116
 117 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE,
 118           "max-inline-insns-recursive",
 119           "The maximum number of instructions inline function can grow to via recursive inlining",
 120           450, 0, 0)
 121
 122 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE_AUTO,
 123           "max-inline-insns-recursive-auto",
 124           "The maximum number of instructions non-inline function can grow to via recursive inlining",
 125           450, 0, 0)
 126
 127 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH,
 128           "max-inline-recursive-depth",
 129           "The maximum depth of recursive inlining for inline functions",
 130           8, 0, 0)
 131
 132 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH_AUTO,
 133           "max-inline-recursive-depth-auto",
 134           "The maximum depth of recursive inlining for non-inline functions",
 135           8, 0, 0)
 136
 137 DEFPARAM (PARAM_MIN_INLINE_RECURSIVE_PROBABILITY,
 138           "min-inline-recursive-probability",
 139           "Inline recursively only when the probability of call being executed exceeds the parameter",
 140           10, 0, 0)
 141
 142 /* Limit the number of expansions created by the variable expansion
 143    optimization to avoid register pressure.  */
 144 DEFPARAM (PARAM_MAX_VARIABLE_EXPANSIONS,
 145           "max-variable-expansions-in-unroller",
 146           "If -fvariable-expansion-in-unroller is used, the maximum number of times that an individual variable will be expanded during loop unrolling",
 147           1, 0, 0)
 148
 149 /* Limit loop autovectorization to loops with large enough iteration count.  */
 150 DEFPARAM (PARAM_MIN_VECT_LOOP_BOUND,
 151           "min-vect-loop-bound",
 152           "If -ftree-vectorize is used, the minimal loop bound of a loop to be considered for vectorization",
 153           0, 0, 0)
 154
 155 /* The maximum number of instructions to consider when looking for an
 156    instruction to fill a delay slot.  If more than this arbitrary
 157    number of instructions is searched, the time savings from filling
 158    the delay slot will be minimal so stop searching.  Increasing
 159    values mean more aggressive optimization, making the compile time
 160    increase with probably small improvement in executable run time.  */
 161 DEFPARAM (PARAM_MAX_DELAY_SLOT_INSN_SEARCH,
 162           "max-delay-slot-insn-search",
 163           "The maximum number of instructions to consider to fill a delay slot",
 164           100, 0, 0)
 165
 166 /* When trying to fill delay slots, the maximum number of instructions
 167    to consider when searching for a block with valid live register
 168    information.  Increasing this arbitrarily chosen value means more
 169    aggressive optimization, increasing the compile time.  This
 170    parameter should be removed when the delay slot code is rewritten
 171    to maintain the control-flow graph.  */
 172 DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
 173          "max-delay-slot-live-search",
 174          "The maximum number of instructions to consider to find accurate live register information",
 175          333, 0, 0)
 176
 177 /* This parameter limits the number of branch elements that the
 178    scheduler will track anti-dependencies through without resetting
 179    the tracking mechanism.  Large functions with few calls or barriers
 180    can generate lists containing many 1000's of dependencies.  Generally
 181    the compiler either uses all available memory, or runs for far too long.  */
 182 DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
 183          "max-pending-list-length",
 184          "The maximum length of scheduling's pending operations list",
 185          32, 0, 0)
 186
 187 DEFPARAM(PARAM_LARGE_FUNCTION_INSNS,
 188          "large-function-insns",
 189          "The size of function body to be considered large",
 190          2700, 0, 0)
 191 DEFPARAM(PARAM_LARGE_FUNCTION_GROWTH,
 192          "large-function-growth",
 193          "Maximal growth due to inlining of large function (in percent)",
 194          100, 0, 0)
 195 DEFPARAM(PARAM_LARGE_UNIT_INSNS,
 196          "large-unit-insns",
 197          "The size of translation unit to be considered large",
 198          10000, 0, 0)
 199 DEFPARAM(PARAM_INLINE_UNIT_GROWTH,
 200          "inline-unit-growth",
 201          "how much can given compilation unit grow because of the inlining (in percent)",
 202          30, 0, 0)
 203 DEFPARAM(PARAM_INLINE_CALL_COST,
 204          "inline-call-cost",
 205          "expense of call operation relative to ordinary arithmetic operations",
 206          16, 0, 0)
 207 DEFPARAM(PARAM_LARGE_STACK_FRAME,
 208          "large-stack-frame",
 209          "The size of stack frame to be considered large",
 210          256, 0, 0)
 211 DEFPARAM(PARAM_STACK_FRAME_GROWTH,
 212          "large-stack-frame-growth",
 213          "Maximal stack frame growth due to inlining (in percent)",
 214          1000, 0, 0)
 215
 216 /* The GCSE optimization will be disabled if it would require
 217    significantly more memory than this value.  */
 218 DEFPARAM(PARAM_MAX_GCSE_MEMORY,
 219          "max-gcse-memory",
 220          "The maximum amount of memory to be allocated by GCSE",
 221          50 * 1024 * 1024, 0, 0)
 222 /* The number of repetitions of copy/const prop and PRE to run.  */
 223 DEFPARAM(PARAM_MAX_GCSE_PASSES,
 224         "max-gcse-passes",
 225         "The maximum number of passes to make when doing GCSE",
 226         1, 1, 0)
 227 /* This is the threshold ratio when to perform partial redundancy
 228    elimination after reload. We perform partial redundancy elimination
 229    when the following holds:
 230    (Redundant load execution count)
 231    ------------------------------- >= GCSE_AFTER_RELOAD_PARTIAL_FRACTION
 232    (Added loads execution count)                                          */
 233 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_PARTIAL_FRACTION,
 234         "gcse-after-reload-partial-fraction",
 235         "The threshold ratio for performing partial redundancy elimination after reload",
 236         3, 0, 0)
 237 /* This is the threshold ratio of the critical edges execution count compared to
 238    the redundant loads execution count that permits performing the load
 239    redundancy elimination in gcse after reload.  */
 240 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_CRITICAL_FRACTION,
 241         "gcse-after-reload-critical-fraction",
 242         "The threshold ratio of critical edges execution count that permit performing redundancy elimination after reload",
 243         10, 0, 0)
 244 /* This parameter limits the number of insns in a loop that will be unrolled,
 245    and by how much the loop is unrolled.
 246
 247    This limit should be at most half of the peeling limits:  loop unroller
 248    decides to not unroll loops that iterate fewer than 2*number of allowed
 249    unrollings and thus we would have loops that are neither peeled or unrolled
 250    otherwise.  */
 251 DEFPARAM(PARAM_MAX_UNROLLED_INSNS,
 252          "max-unrolled-insns",
 253          "The maximum number of instructions to consider to unroll in a loop",
 254          200, 0, 0)
 255 /* This parameter limits how many times the loop is unrolled depending
 256    on number of insns really executed in each iteration.  */
 257 DEFPARAM(PARAM_MAX_AVERAGE_UNROLLED_INSNS,
 258          "max-average-unrolled-insns",
 259          "The maximum number of instructions to consider to unroll in a loop on average",
 260          80, 0, 0)
 261 /* The maximum number of unrollings of a single loop.  */
 262 DEFPARAM(PARAM_MAX_UNROLL_TIMES,
 263         "max-unroll-times",
 264         "The maximum number of unrollings of a single loop",
 265         8, 0, 0)
 266 /* The maximum number of insns of a peeled loop.  */
 267 DEFPARAM(PARAM_MAX_PEELED_INSNS,
 268         "max-peeled-insns",
 269         "The maximum number of insns of a peeled loop",
 270         400, 0, 0)
 271 /* The maximum number of peelings of a single loop.  */
 272 DEFPARAM(PARAM_MAX_PEEL_TIMES,
 273         "max-peel-times",
 274         "The maximum number of peelings of a single loop",
 275         16, 0, 0)
 276 /* The maximum number of insns of a peeled loop.  */
 277 DEFPARAM(PARAM_MAX_COMPLETELY_PEELED_INSNS,
 278         "max-completely-peeled-insns",
 279         "The maximum number of insns of a completely peeled loop",
 280         400, 0, 0)
 281 /* The maximum number of peelings of a single loop that is peeled completely.  */
 282 DEFPARAM(PARAM_MAX_COMPLETELY_PEEL_TIMES,
 283         "max-completely-peel-times",
 284         "The maximum number of peelings of a single loop that is peeled completely",
 285         16, 0, 0)
 286 /* The maximum number of insns of a peeled loop that rolls only once.  */
 287 DEFPARAM(PARAM_MAX_ONCE_PEELED_INSNS,
 288         "max-once-peeled-insns",
 289         "The maximum number of insns of a peeled loop that rolls only once",
 290         400, 0, 0)
 291
 292 /* The maximum number of insns of an unswitched loop.  */
 293 DEFPARAM(PARAM_MAX_UNSWITCH_INSNS,
 294         "max-unswitch-insns",
 295         "The maximum number of insns of an unswitched loop",
 296         50, 0, 0)
 297 /* The maximum level of recursion in unswitch_single_loop.  */
 298 DEFPARAM(PARAM_MAX_UNSWITCH_LEVEL,
 299         "max-unswitch-level",
 300         "The maximum number of unswitchings in a single loop",
 301         3, 0, 0)
 302
 303 /* The maximum number of iterations of a loop the brute force algorithm
 304    for analysis of # of iterations of the loop tries to evaluate.  */
 305 DEFPARAM(PARAM_MAX_ITERATIONS_TO_TRACK,
 306         "max-iterations-to-track",
 307         "Bound on the number of iterations the brute force # of iterations analysis algorithm evaluates",
 308         1000, 0, 0)
 309 /* A cutoff to avoid costly computations of the number of iterations in
 310    the doloop transformation.  */
 311 DEFPARAM(PARAM_MAX_ITERATIONS_COMPUTATION_COST,
 312         "max-iterations-computation-cost",
 313         "Bound on the cost of an expression to compute the number of iterations",
 314         10, 0, 0)
 315
 316 DEFPARAM(PARAM_MAX_SMS_LOOP_NUMBER,
 317          "max-sms-loop-number",
 318          "Maximum number of loops to perform swing modulo scheduling on (mainly for debugging)",
 319          -1, -1, -1)
 320
 321 /* This parameter is used to tune SMS MAX II calculations.  */
 322 DEFPARAM(PARAM_SMS_MAX_II_FACTOR,
 323          "sms-max-ii-factor",
 324          "A factor for tuning the upper bound that swing modulo scheduler uses for scheduling a loop",
 325          100, 0, 0)
 326 DEFPARAM(PARAM_SMS_DFA_HISTORY,
 327          "sms-dfa-history",
 328          "The number of cycles the swing modulo scheduler considers when checking conflicts using DFA",
 329          0, 0, 0)
 330 DEFPARAM(PARAM_SMS_LOOP_AVERAGE_COUNT_THRESHOLD,
 331          "sms-loop-average-count-threshold",
 332          "A threshold on the average loop count considered by the swing modulo scheduler",
 333          0, 0, 0)
 334
 335 DEFPARAM(HOT_BB_COUNT_FRACTION,
 336          "hot-bb-count-fraction",
 337          "Select fraction of the maximal count of repetitions of basic block in program given basic block needs to have to be considered hot",
 338          10000, 0, 0)
 339 DEFPARAM(HOT_BB_FREQUENCY_FRACTION,
 340          "hot-bb-frequency-fraction",
 341          "Select fraction of the maximal frequency of executions of basic block in function given basic block needs to have to be considered hot",
 342          1000, 0, 0)
 343
 344 /* For guessed profiles, the loops having unknown number of iterations
 345    are predicted to iterate relatively few (10) times at average.
 346    For functions containing one loop with large known number of iterations
 347    and other loops having unbounded loops we would end up predicting all
 348    the other loops cold that is not usually the case.  So we need to artificially
 349    flatten the profile.
 350
 351    We need to cut the maximal predicted iterations to large enough iterations
 352    so the loop appears important, but safely within HOT_BB_COUNT_FRACTION
 353    range.  */
 354
 355 DEFPARAM(PARAM_MAX_PREDICTED_ITERATIONS,
 356          "max-predicted-iterations",
 357          "The maximum number of loop iterations we predict statically",
 358          100, 0, 0)
 359 DEFPARAM(TRACER_DYNAMIC_COVERAGE_FEEDBACK,
 360          "tracer-dynamic-coverage-feedback",
 361          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is available",
 362          95, 0, 100)
 363 DEFPARAM(TRACER_DYNAMIC_COVERAGE,
 364          "tracer-dynamic-coverage",
 365          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is not available",
 366          75, 0, 100)
 367 DEFPARAM(TRACER_MAX_CODE_GROWTH,
 368          "tracer-max-code-growth",
 369          "Maximal code growth caused by tail duplication (in percent)",
 370          100, 0, 0)
 371 DEFPARAM(TRACER_MIN_BRANCH_RATIO,
 372          "tracer-min-branch-ratio",
 373          "Stop reverse growth if the reverse probability of best edge is less than this threshold (in percent)",
 374          10, 0, 100)
 375 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK,
 376          "tracer-min-branch-probability-feedback",
 377          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is available",
 378          80, 0, 100)
 379 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY,
 380          "tracer-min-branch-probability",
 381          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is not available",
 382          50, 0, 100)
 383
 384 /* The maximum number of incoming edges to consider for crossjumping.  */
 385 DEFPARAM(PARAM_MAX_CROSSJUMP_EDGES,
 386          "max-crossjump-edges",
 387          "The maximum number of incoming edges to consider for crossjumping",
 388          100, 0, 0)
 389
 390 /* The minimum number of matching instructions to consider for crossjumping.  */
 391 DEFPARAM(PARAM_MIN_CROSSJUMP_INSNS,
 392      "min-crossjump-insns",
 393      "The minimum number of matching instructions to consider for crossjumping",
 394      5, 0, 0)
 395
 396 /* The maximum number expansion factor when copying basic blocks.  */
 397 DEFPARAM(PARAM_MAX_GROW_COPY_BB_INSNS,
 398      "max-grow-copy-bb-insns",
 399      "The maximum expansion factor when copying basic blocks",
 400      8, 0, 0)
 401
 402 /* The maximum number of insns to duplicate when unfactoring computed gotos.  */
 403 DEFPARAM(PARAM_MAX_GOTO_DUPLICATION_INSNS,
 404      "max-goto-duplication-insns",
 405      "The maximum number of insns to duplicate when unfactoring computed gotos",
 406      8, 0, 0)
 407
 408 /* The maximum length of path considered in cse.  */
 409 DEFPARAM(PARAM_MAX_CSE_PATH_LENGTH,
 410          "max-cse-path-length",
 411          "The maximum length of path considered in cse",
 412          10, 0, 0)
 413 DEFPARAM(PARAM_MAX_CSE_INSNS,
 414          "max-cse-insns",
 415          "The maximum instructions CSE process before flushing",
 416          1000, 0, 0)
 417
 418 /* The cost of expression in loop invariant motion that is considered
 419    expensive.  */
 420 DEFPARAM(PARAM_LIM_EXPENSIVE,
 421          "lim-expensive",
 422          "The minimum cost of an expensive expression in the loop invariant motion",
 423          20, 0, 0)
 424
 425 /* Bound on number of candidates for induction variables below that
 426    all candidates are considered for each use in induction variable
 427    optimizations.  */
 428
 429 DEFPARAM(PARAM_IV_CONSIDER_ALL_CANDIDATES_BOUND,
 430          "iv-consider-all-candidates-bound",
 431          "Bound on number of candidates below that all candidates are considered in iv optimizations",
 432          30, 0, 0)
 433
 434 /* The induction variable optimizations give up on loops that contain more
 435    induction variable uses.  */
 436
 437 DEFPARAM(PARAM_IV_MAX_CONSIDERED_USES,
 438          "iv-max-considered-uses",
 439          "Bound on number of iv uses in loop optimized in iv optimizations",
 440          250, 0, 0)
 441
 442 /* If there are at most this number of ivs in the set, try removing unnecessary
 443    ivs from the set always.  */
 444
 445 DEFPARAM(PARAM_IV_ALWAYS_PRUNE_CAND_SET_BOUND,
 446          "iv-always-prune-cand-set-bound",
 447          "If number of candidates in the set is smaller, we always try to remove unused ivs during its optimization",
 448          10, 0, 0)
 449
 450 DEFPARAM(PARAM_SCEV_MAX_EXPR_SIZE,
 451          "scev-max-expr-size",
 452          "Bound on size of expressions used in the scalar evolutions analyzer",
 453          20, 0, 0)
 454
 455 DEFPARAM(PARAM_VECT_MAX_VERSION_CHECKS,
 456          "vect-max-version-checks",
 457          "Bound on number of runtime checks inserted by the vectorizer's loop versioning",
 458          6, 0, 0)
 459
 460 DEFPARAM(PARAM_MAX_CSELIB_MEMORY_LOCATIONS,
 461          "max-cselib-memory-locations",
 462          "The maximum memory locations recorded by cselib",
 463          500, 0, 0)
 464 DEFPARAM(PARAM_MAX_FLOW_MEMORY_LOCATIONS,
 465          "max-flow-memory-locations",
 466          "The maximum memory locations recorded by flow",
 467          100, 0, 0)
 468
 469 #ifdef ENABLE_GC_ALWAYS_COLLECT
 470 # define GGC_MIN_EXPAND_DEFAULT 0
 471 # define GGC_MIN_HEAPSIZE_DEFAULT 0
 472 #else
 473 # define GGC_MIN_EXPAND_DEFAULT 30
 474 # define GGC_MIN_HEAPSIZE_DEFAULT 4096
 475 #endif
 476
 477 DEFPARAM(GGC_MIN_EXPAND,
 478          "ggc-min-expand",
 479          "Minimum heap expansion to trigger garbage collection, as a percentage of the total size of the heap",
 480          GGC_MIN_EXPAND_DEFAULT, 0, 0)
 481
 482 DEFPARAM(GGC_MIN_HEAPSIZE,
 483          "ggc-min-heapsize",
 484          "Minimum heap size before we start collecting garbage, in kilobytes",
 485          GGC_MIN_HEAPSIZE_DEFAULT, 0, 0)
 486
 487 #undef GGC_MIN_EXPAND_DEFAULT
 488 #undef GGC_MIN_HEAPSIZE_DEFAULT
 489
 490 DEFPARAM(PARAM_MAX_RELOAD_SEARCH_INSNS,
 491          "max-reload-search-insns",
 492          "The maximum number of instructions to search backward when looking for equivalent reload",
 493          100, 0, 0)
 494
 495 DEFPARAM(PARAM_MAX_ALIASED_VOPS,
 496          "max-aliased-vops",
 497          "The maximum number of virtual operators per statement allowed to represent aliases before triggering alias grouping",
 498          10, 0, 0)
 499
 500 DEFPARAM(PARAM_MAX_SCHED_REGION_BLOCKS,
 501          "max-sched-region-blocks",
 502          "The maximum number of blocks in a region to be considered for interblock scheduling",
 503          10, 0, 0)
 504
 505 DEFPARAM(PARAM_MAX_SCHED_REGION_INSNS,
 506          "max-sched-region-insns",
 507          "The maximum number of insns in a region to be considered for interblock scheduling",
 508          100, 0, 0)
 509
 510 DEFPARAM(PARAM_MIN_SPEC_PROB,
 511          "min-spec-prob",
 512          "The minimum probability of reaching a source block for interblock speculative scheduling",
 513          40, 0, 0)
 514
 515 DEFPARAM(PARAM_MAX_SCHED_EXTEND_REGIONS_ITERS,
 516          "max-sched-extend-regions-iters",
 517          "The maximum number of iterations through CFG to extend regions",
 518          0, 0, 0)
 519
 520 DEFPARAM(PARAM_MAX_SCHED_INSN_CONFLICT_DELAY,
 521          "max-sched-insn-conflict-delay",
 522          "The maximum conflict delay for an insn to be considered for speculative motion",
 523          3, 1, 10)
 524
 525 DEFPARAM(PARAM_SCHED_SPEC_PROB_CUTOFF,
 526          "sched-spec-prob-cutoff",
 527          "The minimal probability of speculation success (in percents), so that speculative insn will be scheduled.",
 528          40, 0, 100)
 529
 530 DEFPARAM(PARAM_MAX_LAST_VALUE_RTL,
 531          "max-last-value-rtl",
 532          "The maximum number of RTL nodes that can be recorded as combiner's last value",
 533          10000, 0, 0)
 534
 535 /* INTEGER_CST nodes are shared for values [{-1,0} .. N) for
 536    {signed,unsigned} integral types.  This determines N.
 537    Experimentation shows 256 to be a good value.  */
 538 DEFPARAM (PARAM_INTEGER_SHARE_LIMIT,
 539           "integer-share-limit",
 540           "The upper bound for sharing integer constants",
 541           256, 2, 2)
 542
 543 /* Incremental SSA updates for virtual operands may be very slow if
 544    there is a large number of mappings to process.  In those cases, it
 545    is faster to rewrite the virtual symbols from scratch as if they
 546    had been recently introduced.  This heuristic cannot be applied to
 547    SSA mappings for real SSA names, only symbols kept in FUD chains.
 548
 549    PARAM_MIN_VIRTUAL_MAPPINGS specifies the minimum number of virtual
 550    mappings that should be registered to trigger the heuristic.
 551
 552    PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO specifies the ratio between
 553    mappings and symbols.  If the number of virtual mappings is
 554    PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO bigger than the number of
 555    virtual symbols to be updated, then the updater switches to a full
 556    update for those symbols.  */
 557 DEFPARAM (PARAM_MIN_VIRTUAL_MAPPINGS,
 558           "min-virtual-mappings",
 559           "Minimum number of virtual mappings to consider switching to full virtual renames",
 560           100, 0, 0)
 561
 562 DEFPARAM (PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO,
 563           "virtual-mappings-ratio",
 564           "Ratio between virtual mappings and virtual symbols to do full virtual renames",
 565           3, 0, 0)
 566
 567 DEFPARAM (PARAM_SSP_BUFFER_SIZE,
 568           "ssp-buffer-size",
 569           "The lower bound for a buffer to be considered for stack smashing protection",
 570           8, 1, 0)
 571
 572 /* When we thread through a block we have to make copies of the
 573    statements within the block.  Clearly for large blocks the code
 574    duplication is bad.
 575
 576    PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS specifies the maximum number
 577    of statements and PHI nodes allowed in a block which is going to
 578    be duplicated for thread jumping purposes.
 579
 580    Some simple analysis showed that more than 99% of the jump
 581    threading opportunities are for blocks with less than 15
 582    statements.  So we can get the benefits of jump threading
 583    without excessive code bloat for pathological cases with the
 584    throttle set at 15 statements.  */
 585 DEFPARAM (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS,
 586           "max-jump-thread-duplication-stmts",
 587           "Maximum number of statements allowed in a block that needs to be duplicated when threading jumps",
 588           15, 0, 0)
 589
 590 /* This is the maximum number of fields a variable may have before the pointer analysis machinery
 591    will stop trying to treat it in a field-sensitive manner.
 592    There are programs out there with thousands of fields per structure, and handling them
 593    field-sensitively is not worth the cost.  */
 594 DEFPARAM (PARAM_MAX_FIELDS_FOR_FIELD_SENSITIVE,
 595           "max-fields-for-field-sensitive",
 596           "Maximum number of fields in a structure before pointer analysis treats the structure as a single variable",
 597           100, 0, 0)
 598
 599 DEFPARAM(PARAM_MAX_SCHED_READY_INSNS,
 600          "max-sched-ready-insns",
 601          "The maximum number of instructions ready to be issued to be considered by the scheduler during the first scheduling pass",
 602          100, 0, 0)
 603
 604 /* Prefetching and cache-optimizations related parameters.  Default values are
 605    usually set by machine description.  */
 606
 607 /* The number of insns executed before prefetch is completed.  */
 608
 609 DEFPARAM (PARAM_PREFETCH_LATENCY,
 610          "prefetch-latency",
 611          "The number of insns executed before prefetch is completed",
 612          200, 0, 0)
 613
 614 /* The number of prefetches that can run at the same time.  */
 615
 616 DEFPARAM (PARAM_SIMULTANEOUS_PREFETCHES,
 617           "simultaneous-prefetches",
 618           "The number of prefetches that can run at the same time",
 619           3, 0, 0)
 620
 621 /* The size of L1 cache in number of cache lines.  */
 622
 623 DEFPARAM (PARAM_L1_CACHE_SIZE,
 624           "l1-cache-size",
 625           "The size of L1 cache",
 626           1024, 0, 0)
 627
 628 /* The size of L1 cache line in bytes.  */
 629
 630 DEFPARAM (PARAM_L1_CACHE_LINE_SIZE,
 631           "l1-cache-line-size",
 632           "The size of L1 cache line",
 633           32, 0, 0)
 634
 635 #ifdef ENABLE_CHECKING
 636 # define GCC_CANONICAL_TYPES_DEFAULT 1
 637 #else
 638 # define GCC_CANONICAL_TYPES_DEFAULT 0
 639 #endif
 640
 641 /* Whether we should verify that the canonical types in the system are
 642    consistent with the "structural" typing. */
 643
 644 DEFPARAM (PARAM_VERIFY_CANONICAL_TYPES,
 645           "verify-canonical-types",
 646           "Whether to verify canonical types",
 647           GCC_CANONICAL_TYPES_DEFAULT, 0, 1)
 648 /*
 649 Local variables:
 650 mode:c
 651 End: */