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, 59 Temple Place - Suite 330, Boston, MA
  20 02111-1307, USA.
  21
  22 */
  23
  24 /* This file contains definitions for language-independent
  25    parameters.  The DEFPARAM macro takes 4 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    Be sure to add an entry to invoke.texi summarizing the parameter.  */
  37
  38 /* The maximum structure size at which the scalar replacement of
  39    aggregates (SRA) pass will perform block copies.  The default
  40    value, 0, implies that GCC will select the most appropriate size
  41    itself.  */
  42 DEFPARAM (PARAM_SRA_MAX_STRUCTURE_SIZE,
  43           "sra-max-structure-size",
  44           "The maximum structure size (in bytes) at which GCC will do block copies",
  45           0, 0, 0)
  46
  47 /* The ratio between instantiated fields and the complete structure
  48    size.  We say that if the ratio of the number of bytes in
  49    instantiated fields to the number of bytes in the complete
  50    structure exceeds this parameter, then block copies are not used.
  51    The default is 75%.  */
  52 DEFPARAM (PARAM_SRA_FIELD_STRUCTURE_RATIO,
  53           "sra-field-structure-ratio",
  54           "The threshold ratio between instantiated fields and the total structure size",
  55           75, 0, 100)
  56
  57 /* The single function inlining limit. This is the maximum size
  58    of a function counted in internal gcc instructions (not in
  59    real machine instructions) that is eligible for inlining
  60    by the tree inliner.
  61    The default value is 500.
  62    Only functions marked inline (or methods defined in the class
  63    definition for C++) are affected by this, unless you set the
  64    -finline-functions (included in -O3) compiler option.
  65    There are more restrictions to inlining: If inlined functions
  66    call other functions, the already inlined instructions are
  67    counted and once the recursive inline limit (see
  68    "max-inline-insns" parameter) is exceeded, the acceptable size
  69    gets decreased.  */
  70 DEFPARAM (PARAM_MAX_INLINE_INSNS_SINGLE,
  71           "max-inline-insns-single",
  72           "The maximum number of instructions in a single function eligible for inlining",
  73           500, 0, 0)
  74
  75 /* The single function inlining limit for functions that are
  76    inlined by virtue of -finline-functions (-O3).
  77    This limit should be chosen to be below or equal to the limit
  78    that is applied to functions marked inlined (or defined in the
  79    class declaration in C++) given by the "max-inline-insns-single"
  80    parameter.
  81    The default value is 150.  */
  82 DEFPARAM (PARAM_MAX_INLINE_INSNS_AUTO,
  83           "max-inline-insns-auto",
  84           "The maximum number of instructions when automatically inlining",
  85           120, 0, 0)
  86
  87 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE,
  88           "max-inline-insns-recursive",
  89           "The maximum number of instructions inline function can grow to via recursive inlining",
  90           500, 0, 0)
  91
  92 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE_AUTO,
  93           "max-inline-insns-recursive-auto",
  94           "The maximum number of instructions non-inline function can grow to via recursive inlining",
  95           500, 0, 0)
  96
  97 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH,
  98           "max-inline-recursive-depth",
  99           "The maximum depth of recursive inlining for inline functions",
 100           8, 0, 0)
 101
 102 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH_AUTO,
 103           "max-inline-recursive-depth-auto",
 104           "The maximum depth of recursive inlining for non-inline functions",
 105           8, 0, 0)
 106
 107 /* Limit the number of expansions created by the variable expansion
 108    optimization to avoid register pressure.  */
 109 DEFPARAM (PARAM_MAX_VARIABLE_EXPANSIONS,
 110           "max-variable-expansions-in-unroller",
 111           "If -fvariable-expansion-in-unroller is used, the maximum number of \
 112            times that an individual variable will be expanded \
 113            during loop unrolling",
 114           1, 0, 0)
 115
 116 /* The maximum number of instructions to consider when looking for an
 117    instruction to fill a delay slot.  If more than this arbitrary
 118    number of instructions is searched, the time savings from filling
 119    the delay slot will be minimal so stop searching.  Increasing
 120    values mean more aggressive optimization, making the compile time
 121    increase with probably small improvement in executable run time.  */
 122 DEFPARAM (PARAM_MAX_DELAY_SLOT_INSN_SEARCH,
 123           "max-delay-slot-insn-search",
 124           "The maximum number of instructions to consider to fill a delay slot",
 125           100, 0, 0)
 126
 127 /* When trying to fill delay slots, the maximum number of instructions
 128    to consider when searching for a block with valid live register
 129    information.  Increasing this arbitrarily chosen value means more
 130    aggressive optimization, increasing the compile time.  This
 131    parameter should be removed when the delay slot code is rewritten
 132    to maintain the control-flow graph.  */
 133 DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
 134          "max-delay-slot-live-search",
 135          "The maximum number of instructions to consider to find accurate live register information",
 136          333, 0, 0)
 137
 138 /* This parameter limits the number of branch elements that the
 139    scheduler will track anti-dependencies through without resetting
 140    the tracking mechanism.  Large functions with few calls or barriers
 141    can generate lists containing many 1000's of dependencies.  Generally
 142    the compiler either uses all available memory, or runs for far too long.  */
 143 DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
 144          "max-pending-list-length",
 145          "The maximum length of scheduling's pending operations list",
 146          32, 0, 0)
 147
 148 DEFPARAM(PARAM_LARGE_FUNCTION_INSNS,
 149          "large-function-insns",
 150          "The size of function body to be considered large",
 151          3000, 0, 0)
 152 DEFPARAM(PARAM_LARGE_FUNCTION_GROWTH,
 153          "large-function-growth",
 154          "Maximal growth due to inlining of large function (in percent)",
 155          100, 0, 0)
 156 DEFPARAM(PARAM_INLINE_UNIT_GROWTH,
 157          "inline-unit-growth",
 158          "how much can given compilation unit grow because of the inlining (in percent)",
 159          50, 0, 0)
 160
 161 /* The GCSE optimization will be disabled if it would require
 162    significantly more memory than this value.  */
 163 DEFPARAM(PARAM_MAX_GCSE_MEMORY,
 164          "max-gcse-memory",
 165          "The maximum amount of memory to be allocated by GCSE",
 166          50 * 1024 * 1024, 0, 0)
 167 /* The number of repetitions of copy/const prop and PRE to run.  */
 168 DEFPARAM(PARAM_MAX_GCSE_PASSES,
 169         "max-gcse-passes",
 170         "The maximum number of passes to make when doing GCSE",
 171         1, 1, 0)
 172 /* This is the threshold ratio when to perform partial redundancy
 173    elimination after reload. We perform partial redundancy elimination
 174    when the following holds:
 175    (Redundant load execution count)
 176    ------------------------------- >= GCSE_AFTER_RELOAD_PARTIAL_FRACTION
 177    (Added loads execution count)                                          */
 178 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_PARTIAL_FRACTION,
 179         "gcse-after-reload-partial-fraction",
 180         "The threshold ratio for performing partial redundancy elimination after reload.",
 181         3, 0, 0)
 182 /* This is the threshold ratio of the critical edges execution count compared to
 183    the redundant loads execution count that permits performing the load
 184    redundancy elimination in gcse after reload.  */
 185 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_CRITICAL_FRACTION,
 186         "gcse-after-reload-critical-fraction",
 187         "The threshold ratio of critical edges execution count that permit performing redundancy elimination after reload.",
 188         10, 0, 0)
 189 /* This parameter limits the number of insns in a loop that will be unrolled,
 190    and by how much the loop is unrolled.
 191
 192    This limit should be at most half of the peeling limits:  loop unroller
 193    decides to not unroll loops that iterate fewer than 2*number of allowed
 194    unrollings and thus we would have loops that are neither peeled or unrolled
 195    otherwise.  */
 196 DEFPARAM(PARAM_MAX_UNROLLED_INSNS,
 197          "max-unrolled-insns",
 198          "The maximum number of instructions to consider to unroll in a loop",
 199          200, 0, 0)
 200 /* This parameter limits how many times the loop is unrolled depending
 201    on number of insns really executed in each iteration.  */
 202 DEFPARAM(PARAM_MAX_AVERAGE_UNROLLED_INSNS,
 203          "max-average-unrolled-insns",
 204          "The maximum number of instructions to consider to unroll in a loop on average",
 205          80, 0, 0)
 206 /* The maximum number of unrollings of a single loop.  */
 207 DEFPARAM(PARAM_MAX_UNROLL_TIMES,
 208         "max-unroll-times",
 209         "The maximum number of unrollings of a single loop",
 210         8, 0, 0)
 211 /* The maximum number of insns of a peeled loop.  */
 212 DEFPARAM(PARAM_MAX_PEELED_INSNS,
 213         "max-peeled-insns",
 214         "The maximum number of insns of a peeled loop",
 215         400, 0, 0)
 216 /* The maximum number of peelings of a single loop.  */
 217 DEFPARAM(PARAM_MAX_PEEL_TIMES,
 218         "max-peel-times",
 219         "The maximum number of peelings of a single loop",
 220         16, 0, 0)
 221 /* The maximum number of insns of a peeled loop.  */
 222 DEFPARAM(PARAM_MAX_COMPLETELY_PEELED_INSNS,
 223         "max-completely-peeled-insns",
 224         "The maximum number of insns of a completely peeled loop",
 225         400, 0, 0)
 226 /* The maximum number of peelings of a single loop that is peeled completely.  */
 227 DEFPARAM(PARAM_MAX_COMPLETELY_PEEL_TIMES,
 228         "max-completely-peel-times",
 229         "The maximum number of peelings of a single loop that is peeled completely",
 230         16, 0, 0)
 231 /* The maximum number of insns of a peeled loop that rolls only once.  */
 232 DEFPARAM(PARAM_MAX_ONCE_PEELED_INSNS,
 233         "max-once-peeled-insns",
 234         "The maximum number of insns of a peeled loop that rolls only once",
 235         400, 0, 0)
 236
 237 /* The maximum number of insns of an unswitched loop.  */
 238 DEFPARAM(PARAM_MAX_UNSWITCH_INSNS,
 239         "max-unswitch-insns",
 240         "The maximum number of insns of an unswitched loop",
 241         50, 0, 0)
 242 /* The maximum level of recursion in unswitch_single_loop.  */
 243 DEFPARAM(PARAM_MAX_UNSWITCH_LEVEL,
 244         "max-unswitch-level",
 245         "The maximum number of unswitchings in a single loop",
 246         3, 0, 0)
 247
 248 /* The maximum number of iterations of a loop the brute force algorithm
 249    for analysis of # of iterations of the loop tries to evaluate.  */
 250 DEFPARAM(PARAM_MAX_ITERATIONS_TO_TRACK,
 251         "max-iterations-to-track",
 252         "Bound on the number of iterations the brute force # of iterations analysis algorithm evaluates",
 253         1000, 0, 0)
 254
 255 DEFPARAM(PARAM_MAX_SMS_LOOP_NUMBER,
 256          "max-sms-loop-number",
 257          "Maximum number of loops to perform swing modulo scheduling on (mainly for debugging)",
 258          -1, -1, -1)
 259
 260 /* This parameter is used to tune SMS MAX II calculations.  */
 261 DEFPARAM(PARAM_SMS_MAX_II_FACTOR,
 262          "sms-max-ii-factor",
 263          "A factor for tuning the upper bound that swing modulo scheduler uses for scheduling a loop",
 264          100, 0, 0)
 265 DEFPARAM(PARAM_SMS_DFA_HISTORY,
 266          "sms-dfa-history",
 267          "The number of cycles the swing modulo scheduler considers when \
 268           checking conflicts using DFA",
 269          0, 0, 0)
 270 DEFPARAM(PARAM_SMS_LOOP_AVERAGE_COUNT_THRESHOLD,
 271          "sms-loop-average-count-threshold",
 272          "A threshold on the average loop count considered by the swing modulo scheduler",
 273          0, 0, 0)
 274
 275 DEFPARAM(HOT_BB_COUNT_FRACTION,
 276          "hot-bb-count-fraction",
 277          "Select fraction of the maximal count of repetitions of basic block in program given basic block needs to have to be considered hot",
 278          10000, 0, 0)
 279 DEFPARAM(HOT_BB_FREQUENCY_FRACTION,
 280          "hot-bb-frequency-fraction",
 281          "Select fraction of the maximal frequency of executions of basic block in function given basic block needs to have to be considered hot",
 282          1000, 0, 0)
 283 DEFPARAM(TRACER_DYNAMIC_COVERAGE_FEEDBACK,
 284          "tracer-dynamic-coverage-feedback",
 285          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is available",
 286          95, 0, 100)
 287 DEFPARAM(TRACER_DYNAMIC_COVERAGE,
 288          "tracer-dynamic-coverage",
 289          "The percentage of function, weighted by execution frequency, that must be covered by trace formation. Used when profile feedback is not available",
 290          75, 0, 100)
 291 DEFPARAM(TRACER_MAX_CODE_GROWTH,
 292          "tracer-max-code-growth",
 293          "Maximal code growth caused by tail duplication (in percent)",
 294          100, 0, 0)
 295 DEFPARAM(TRACER_MIN_BRANCH_RATIO,
 296          "tracer-min-branch-ratio",
 297          "Stop reverse growth if the reverse probability of best edge is less than this threshold (in percent)",
 298          10, 0, 100)
 299 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK,
 300          "tracer-min-branch-probability-feedback",
 301          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is available",
 302          80, 0, 100)
 303 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY,
 304          "tracer-min-branch-probability",
 305          "Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is not available",
 306          50, 0, 100)
 307
 308 /* The maximum number of incoming edges to consider for crossjumping.  */
 309 DEFPARAM(PARAM_MAX_CROSSJUMP_EDGES,
 310          "max-crossjump-edges",
 311          "The maximum number of incoming edges to consider for crossjumping",
 312          100, 0, 0)
 313
 314 /* The minimum number of matching instructions to consider for crossjumping.  */
 315 DEFPARAM(PARAM_MIN_CROSSJUMP_INSNS,
 316      "min-crossjump-insns",
 317      "The minimum number of matching instructions to consider for crossjumping",
 318      5, 0, 0)
 319
 320 /* The maximum number of insns to duplicate when unfactoring computed gotos.  */
 321 DEFPARAM(PARAM_MAX_GOTO_DUPLICATION_INSNS,
 322      "max-goto-duplication-insns",
 323      "The maximum number of insns to duplicate when unfactoring computed gotos",
 324      8, 0, 0)
 325
 326 /* The maximum length of path considered in cse.  */
 327 DEFPARAM(PARAM_MAX_CSE_PATH_LENGTH,
 328          "max-cse-path-length",
 329          "The maximum length of path considered in cse",
 330          10, 0, 0)
 331
 332 /* The cost of expression in loop invariant motion that is considered
 333    expensive.  */
 334 DEFPARAM(PARAM_LIM_EXPENSIVE,
 335          "lim-expensive",
 336          "The minimum cost of an expensive expression in the loop invariant motion",
 337          20, 0, 0)
 338
 339 /* Bound on number of candidates for induction variables below that
 340    all candidates are considered for each use in induction variable
 341    optimizations.  */
 342
 343 DEFPARAM(PARAM_IV_CONSIDER_ALL_CANDIDATES_BOUND,
 344          "iv-consider-all-candidates-bound",
 345          "Bound on number of candidates below that all candidates are considered in iv optimizations",
 346          30, 0, 0)
 347
 348 /* The induction variable optimizations give up on loops that contain more
 349    induction variable uses.  */
 350
 351 DEFPARAM(PARAM_IV_MAX_CONSIDERED_USES,
 352          "iv-max-considered-uses",
 353          "Bound on number of iv uses in loop optimized in iv optimizations",
 354          250, 0, 0)
 355
 356 /* If there are at most this number of ivs in the set, try removing unnecessary
 357    ivs from the set always.  */
 358
 359 DEFPARAM(PARAM_IV_ALWAYS_PRUNE_CAND_SET_BOUND,
 360          "iv-always-prune-cand-set-bound",
 361          "If number of candidates in the set is smaller, we always try to remove unused ivs during its optimization",
 362          10, 0, 0)
 363
 364 /* The product of the next two is used to decide whether or not to
 365    use .GLOBAL_VAR.  See tree-dfa.c.  */
 366 DEFPARAM(PARAM_GLOBAL_VAR_THRESHOLD,
 367         "global-var-threshold",
 368         "Given N calls and V call-clobbered vars in a function.  Use .GLOBAL_VAR if NxV is larger than this limit",
 369         500000, 0, 0)
 370
 371 DEFPARAM(PARAM_MAX_CSELIB_MEMORY_LOCATIONS,
 372          "max-cselib-memory-locations",
 373          "The maximum memory locations recorded by cselib",
 374          500, 0, 0)
 375
 376 #ifdef ENABLE_GC_ALWAYS_COLLECT
 377 # define GGC_MIN_EXPAND_DEFAULT 0
 378 # define GGC_MIN_HEAPSIZE_DEFAULT 0
 379 #else
 380 # define GGC_MIN_EXPAND_DEFAULT 30
 381 # define GGC_MIN_HEAPSIZE_DEFAULT 4096
 382 #endif
 383
 384 DEFPARAM(GGC_MIN_EXPAND,
 385          "ggc-min-expand",
 386          "Minimum heap expansion to trigger garbage collection, as a percentage of the total size of the heap",
 387          GGC_MIN_EXPAND_DEFAULT, 0, 0)
 388
 389 DEFPARAM(GGC_MIN_HEAPSIZE,
 390          "ggc-min-heapsize",
 391          "Minimum heap size before we start collecting garbage, in kilobytes",
 392          GGC_MIN_HEAPSIZE_DEFAULT, 0, 0)
 393
 394 #undef GGC_MIN_EXPAND_DEFAULT
 395 #undef GGC_MIN_HEAPSIZE_DEFAULT
 396
 397 DEFPARAM(PARAM_MAX_RELOAD_SEARCH_INSNS,
 398          "max-reload-search-insns",
 399          "The maximum number of instructions to search backward when looking for equivalent reload",
 400          100, 0, 0)
 401
 402 DEFPARAM(PARAM_MAX_ALIASED_VOPS,
 403          "max-aliased-vops",
 404          "The maximum number of virtual operands allowed to represent aliases before triggering alias grouping.",
 405          500, 0, 0)
 406
 407 DEFPARAM(PARAM_MAX_SCHED_REGION_BLOCKS,
 408          "max-sched-region-blocks",
 409          "The maximum number of blocks in a region to be considered for interblock scheduling",
 410          10, 0, 0)
 411
 412 DEFPARAM(PARAM_MAX_SCHED_REGION_INSNS,
 413          "max-sched-region-insns",
 414          "The maximum number of insns in a region to be considered for interblock scheduling",
 415          100, 0, 0)
 416
 417 DEFPARAM(PARAM_MAX_LAST_VALUE_RTL,
 418          "max-last-value-rtl",
 419          "The maximum number of RTL nodes that can be recorded as combiner's last value",
 420          10000, 0, 0)
 421
 422 /* INTEGER_CST nodes are shared for values [{-1,0} .. N) for
 423    {signed,unsigned} integral types.  This determines N.
 424    Experimentation shows 256 to be a good value.  */
 425 DEFPARAM (PARAM_INTEGER_SHARE_LIMIT,
 426           "integer-share-limit",
 427           "The upper bound for sharing integer constants",
 428           256, 2, 2)
 429
 430 /*
 431 Local variables:
 432 mode:c
 433 End: */