gcc/params.def

   1 /* params.def - Run-time parameters.
   2    Copyright (C) 2001, 2002, 2004 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)
  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)
  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)
  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)
  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)
  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)
  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)
 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)
 106
 107 /* For languages that (still) use the RTL inliner, we can specify
 108    limits for the RTL inliner separately.
 109    The parameter here defines the maximum number of RTL instructions
 110    a function may have to be eligible for inlining in the RTL inliner.
 111    The default value is 600.  */
 112 DEFPARAM (PARAM_MAX_INLINE_INSNS_RTL,
 113           "max-inline-insns-rtl",
 114           "The maximum number of instructions for the RTL inliner",
 115           600)
 116
 117 /* Limit the number of expansions created by the variable expansion
 118    optimization to avoid register pressure.  */
 119 DEFPARAM (PARAM_MAX_VARIABLE_EXPANSIONS,
 120           "max-variable-expansions-in-unroller",
 121           "If -fvariable-expansion-in-unroller is used, the maximum number of \
 122            times that an individual variable will be expanded \
 123            during loop unrolling",
 124           1)
 125
 126 /* The maximum number of instructions to consider when looking for an
 127    instruction to fill a delay slot.  If more than this arbitrary
 128    number of instructions is searched, the time savings from filling
 129    the delay slot will be minimal so stop searching.  Increasing
 130    values mean more aggressive optimization, making the compile time
 131    increase with probably small improvement in executable run time.  */
 132 DEFPARAM (PARAM_MAX_DELAY_SLOT_INSN_SEARCH,
 133           "max-delay-slot-insn-search",
 134           "The maximum number of instructions to consider to fill a delay slot",
 135           100)
 136
 137 /* When trying to fill delay slots, the maximum number of instructions
 138    to consider when searching for a block with valid live register
 139    information.  Increasing this arbitrarily chosen value means more
 140    aggressive optimization, increasing the compile time.  This
 141    parameter should be removed when the delay slot code is rewritten
 142    to maintain the control-flow graph.  */
 143 DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
 144          "max-delay-slot-live-search",
 145          "The maximum number of instructions to consider to find accurate live register information",
 146          333)
 147
 148 /* This parameter limits the number of branch elements that the
 149    scheduler will track anti-dependencies through without resetting
 150    the tracking mechanism.  Large functions with few calls or barriers
 151    can generate lists containing many 1000's of dependencies.  Generally
 152    the compiler either uses all available memory, or runs for far too long.  */
 153 DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
 154          "max-pending-list-length",
 155          "The maximum length of scheduling's pending operations list",
 156          32)
 157
 158 DEFPARAM(PARAM_LARGE_FUNCTION_INSNS,
 159          "large-function-insns",
 160          "The size of function body to be considered large",
 161          3000)
 162 DEFPARAM(PARAM_LARGE_FUNCTION_GROWTH,
 163          "large-function-growth",
 164          "Maximal growth due to inlining of large function (in percent)",
 165          100)
 166 DEFPARAM(PARAM_INLINE_UNIT_GROWTH,
 167          "inline-unit-growth",
 168          "how much can given compilation unit grow because of the inlining (in percent)",
 169          50)
 170
 171 /* The GCSE optimization will be disabled if it would require
 172    significantly more memory than this value.  */
 173 DEFPARAM(PARAM_MAX_GCSE_MEMORY,
 174          "max-gcse-memory",
 175          "The maximum amount of memory to be allocated by GCSE",
 176          50 * 1024 * 1024)
 177 /* The number of repetitions of copy/const prop and PRE to run.  */
 178 DEFPARAM(PARAM_MAX_GCSE_PASSES,
 179         "max-gcse-passes",
 180         "The maximum number of passes to make when doing GCSE",
 181         1)
 182 /* This is the threshold ratio when to perform partial redundancy
 183    elimination after reload. We perform partial redundancy elimination
 184    when the following holds:
 185    (Redundant load execution count)
 186    ------------------------------- >= GCSE_AFTER_RELOAD_PARTIAL_FRACTION
 187    (Added loads execution count)                                          */
 188 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_PARTIAL_FRACTION,
 189         "gcse-after-reload-partial-fraction",
 190         "The threshold ratio for performing partial redundancy elimination \
 191          after reload.",
 192         3)
 193 /* This is the threshold ratio of the critical edges execution count compared to
 194    the redundant loads execution count that permits performing the load
 195    redundancy elimination in gcse after reload.  */
 196 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_CRITICAL_FRACTION,
 197         "gcse-after-reload-critical-fraction",
 198         "The threshold ratio of critical edges execution count that permit \
 199          performing redundancy elimination after reload.",
 200         10)
 201 /* This parameter limits the number of insns in a loop that will be unrolled,
 202    and by how much the loop is unrolled.
 203
 204    This limit should be at most half of the peeling limits:  loop unroller
 205    decides to not unroll loops that iterate fewer than 2*number of allowed
 206    unrollings and thus we would have loops that are neither peeled or unrolled
 207    otherwise.  */
 208 DEFPARAM(PARAM_MAX_UNROLLED_INSNS,
 209          "max-unrolled-insns",
 210          "The maximum number of instructions to consider to unroll in a loop",
 211          200)
 212 /* This parameter limits how many times the loop is unrolled depending
 213    on number of insns really executed in each iteration.  */
 214 DEFPARAM(PARAM_MAX_AVERAGE_UNROLLED_INSNS,
 215          "max-average-unrolled-insns",
 216          "The maximum number of instructions to consider to unroll in a loop on average",
 217          80)
 218 /* The maximum number of unrollings of a single loop.  */
 219 DEFPARAM(PARAM_MAX_UNROLL_TIMES,
 220         "max-unroll-times",
 221         "The maximum number of unrollings of a single loop",
 222         8)
 223 /* The maximum number of insns of a peeled loop.  */
 224 DEFPARAM(PARAM_MAX_PEELED_INSNS,
 225         "max-peeled-insns",
 226         "The maximum number of insns of a peeled loop",
 227         400)
 228 /* The maximum number of peelings of a single loop.  */
 229 DEFPARAM(PARAM_MAX_PEEL_TIMES,
 230         "max-peel-times",
 231         "The maximum number of peelings of a single loop",
 232         16)
 233 /* The maximum number of insns of a peeled loop.  */
 234 DEFPARAM(PARAM_MAX_COMPLETELY_PEELED_INSNS,
 235         "max-completely-peeled-insns",
 236         "The maximum number of insns of a completely peeled loop",
 237         400)
 238 /* The maximum number of peelings of a single loop that is peeled completely.  */
 239 DEFPARAM(PARAM_MAX_COMPLETELY_PEEL_TIMES,
 240         "max-completely-peel-times",
 241         "The maximum number of peelings of a single loop that is peeled completely",
 242         16)
 243 /* The maximum number of insns of a peeled loop that rolls only once.  */
 244 DEFPARAM(PARAM_MAX_ONCE_PEELED_INSNS,
 245         "max-once-peeled-insns",
 246         "The maximum number of insns of a peeled loop that rolls only once",
 247         400)
 248
 249 /* The maximum number of insns of an unswitched loop.  */
 250 DEFPARAM(PARAM_MAX_UNSWITCH_INSNS,
 251         "max-unswitch-insns",
 252         "The maximum number of insns of an unswitched loop",
 253         50)
 254 /* The maximum level of recursion in unswitch_single_loop.  */
 255 DEFPARAM(PARAM_MAX_UNSWITCH_LEVEL,
 256         "max-unswitch-level",
 257         "The maximum number of unswitchings in a single loop",
 258         3)
 259
 260 /* The maximum number of iterations of a loop the brute force algorithm
 261    for analysis of # of iterations of the loop tries to evaluate.  */
 262 DEFPARAM(PARAM_MAX_ITERATIONS_TO_TRACK,
 263         "max-iterations-to-track",
 264         "Bound on the number of iterations the brute force # of iterations \
 265          analysis algorithm evaluates",
 266         1000)
 267
 268 DEFPARAM(PARAM_MAX_SMS_LOOP_NUMBER,
 269          "max-sms-loop-number",
 270          "Maximum number of loops to perform swing modulo scheduling on \
 271           (mainly for debugging)",
 272          -1)
 273
 274 /* This parameter is used to tune SMS MAX II calculations.  */
 275 DEFPARAM(PARAM_SMS_MAX_II_FACTOR,
 276          "sms-max-ii-factor",
 277          "A factor for tuning the upper bound that swing modulo scheduler uses \
 278           for scheduling a loop",
 279          100)
 280 DEFPARAM(PARAM_SMS_DFA_HISTORY,
 281          "sms-dfa-history",
 282          "The number of cycles the swing modulo scheduler considers when \
 283           checking conflicts using DFA",
 284          0)
 285 DEFPARAM(PARAM_SMS_LOOP_AVERAGE_COUNT_THRESHOLD,
 286          "sms-loop-average-count-threshold",
 287          "A threshold on the average loop count considered by the swing modulo \
 288           scheduler",
 289          0)
 290
 291 DEFPARAM(HOT_BB_COUNT_FRACTION,
 292          "hot-bb-count-fraction",
 293          "Select fraction of the maximal count of repetitions of basic block in \
 294 program given basic block needs to have to be considered hot",
 295          10000)
 296 DEFPARAM(HOT_BB_FREQUENCY_FRACTION,
 297          "hot-bb-frequency-fraction",
 298          "Select fraction of the maximal frequency of executions of basic \
 299 block in function given basic block needs to have to be considered hot",
 300          1000)
 301 DEFPARAM(TRACER_DYNAMIC_COVERAGE_FEEDBACK,
 302          "tracer-dynamic-coverage-feedback",
 303          "The percentage of function, weighted by execution frequency, that \
 304 must be covered by trace formation. Used when profile feedback is available",
 305          95)
 306 DEFPARAM(TRACER_DYNAMIC_COVERAGE,
 307          "tracer-dynamic-coverage",
 308          "The percentage of function, weighted by execution frequency, that \
 309 must be covered by trace formation. Used when profile feedback is not available",
 310          75)
 311 DEFPARAM(TRACER_MAX_CODE_GROWTH,
 312          "tracer-max-code-growth",
 313          "Maximal code growth caused by tail duplication (in percent)",
 314          100)
 315 DEFPARAM(TRACER_MIN_BRANCH_RATIO,
 316          "tracer-min-branch-ratio",
 317          "Stop reverse growth if the reverse probability of best edge is less \
 318 than this threshold (in percent)",
 319          10)
 320 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK,
 321          "tracer-min-branch-probability-feedback",
 322          "Stop forward growth if the probability of best edge is less than \
 323 this threshold (in percent). Used when profile feedback is available",
 324          80)
 325 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY,
 326          "tracer-min-branch-probability",
 327          "Stop forward growth if the probability of best edge is less than \
 328 this threshold (in percent). Used when profile feedback is not available",
 329          50)
 330
 331 /* The maximum number of incoming edges to consider for crossjumping.  */
 332 DEFPARAM(PARAM_MAX_CROSSJUMP_EDGES,
 333          "max-crossjump-edges",
 334          "The maximum number of incoming edges to consider for crossjumping",
 335          100)
 336
 337 /* The minimum number of matching instructions to consider for crossjumping.  */
 338 DEFPARAM(PARAM_MIN_CROSSJUMP_INSNS,
 339      "min-crossjump-insns",
 340      "The minimum number of matching instructions to consider for crossjumping",
 341      5)
 342
 343 /* The maximum length of path considered in cse.  */
 344 DEFPARAM(PARAM_MAX_CSE_PATH_LENGTH,
 345          "max-cse-path-length",
 346          "The maximum length of path considered in cse",
 347          10)
 348
 349 /* The cost of expression in loop invariant motion that is considered
 350    expensive.  */
 351 DEFPARAM(PARAM_LIM_EXPENSIVE,
 352          "lim-expensive",
 353          "The minimum cost of an expensive expression in the loop invariant motion",
 354          20)
 355
 356 /* Bound on number of candidates for induction variables below that
 357    all candidates are considered for each use in induction variable
 358    optimizations.  */
 359
 360 DEFPARAM(PARAM_IV_CONSIDER_ALL_CANDIDATES_BOUND,
 361          "iv-consider-all-candidates-bound",
 362          "Bound on number of candidates below that all candidates are considered in iv optimizations",
 363          30)
 364
 365 /* The induction variable optimizations give up on loops that contain more
 366    induction variable uses.  */
 367
 368 DEFPARAM(PARAM_IV_MAX_CONSIDERED_USES,
 369          "iv-max-considered-uses",
 370          "Bound on number of iv uses in loop optimized in iv optimizations",
 371          250)
 372
 373 /* The product of the next two is used to decide whether or not to
 374    use .GLOBAL_VAR.  See tree-dfa.c.  */
 375 DEFPARAM(PARAM_GLOBAL_VAR_THRESHOLD,
 376         "global-var-threshold",
 377         "Given N calls and V call-clobbered vars in a function.  Use .GLOBAL_VAR if NxV is larger than this limit",
 378         500000)
 379
 380 DEFPARAM(PARAM_MAX_CSELIB_MEMORY_LOCATIONS,
 381          "max-cselib-memory-locations",
 382          "The maximum memory locations recorded by cselib",
 383          500)
 384
 385 #ifdef ENABLE_GC_ALWAYS_COLLECT
 386 # define GGC_MIN_EXPAND_DEFAULT 0
 387 # define GGC_MIN_HEAPSIZE_DEFAULT 0
 388 #else
 389 # define GGC_MIN_EXPAND_DEFAULT 30
 390 # define GGC_MIN_HEAPSIZE_DEFAULT 4096
 391 #endif
 392
 393 DEFPARAM(GGC_MIN_EXPAND,
 394          "ggc-min-expand",
 395          "Minimum heap expansion to trigger garbage collection, as \
 396 a percentage of the total size of the heap",
 397          GGC_MIN_EXPAND_DEFAULT)
 398
 399 DEFPARAM(GGC_MIN_HEAPSIZE,
 400          "ggc-min-heapsize",
 401          "Minimum heap size before we start collecting garbage, in kilobytes",
 402          GGC_MIN_HEAPSIZE_DEFAULT)
 403
 404 #undef GGC_MIN_EXPAND_DEFAULT
 405 #undef GGC_MIN_HEAPSIZE_DEFAULT
 406
 407 DEFPARAM(PARAM_MAX_RELOAD_SEARCH_INSNS,
 408          "max-reload-search-insns",
 409          "The maximum number of instructions to search backward when looking for equivalent reload",
 410          100)
 411
 412 DEFPARAM(PARAM_MAX_ALIASED_VOPS,
 413          "max-aliased-vops",
 414          "The maximum number of virtual operands allowed to represent aliases before triggering alias grouping.",
 415          500)
 416
 417 DEFPARAM(PARAM_MAX_SCHED_REGION_BLOCKS,
 418          "max-sched-region-blocks",
 419          "The maximum number of blocks in a region to be considered for interblock scheduling",
 420          10)
 421
 422 DEFPARAM(PARAM_MAX_SCHED_REGION_INSNS,
 423          "max-sched-region-insns",
 424          "The maximum number of insns in a region to be considered for interblock scheduling",
 425          100)
 426
 427 /* INTEGER_CST nodes are shared for values [{-1,0} .. N) for
 428    {signed,unsigned} integral types.  This determines N.
 429    Experimentation shows 256 to be a good value.  */
 430 DEFPARAM (PARAM_INTEGER_SHARE_LIMIT,
 431           "integer-share-limit",
 432           "The upper bound for sharing integer constants",
 433           256)
 434
 435 /*
 436 Local variables:
 437 mode:c
 438 End: */