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 single function inlining limit. This is the maximum size
  39    of a function counted in internal gcc instructions (not in
  40    real machine instructions) that is eligible for inlining
  41    by the tree inliner.
  42    The default value is 500.
  43    Only functions marked inline (or methods defined in the class
  44    definition for C++) are affected by this, unless you set the
  45    -finline-functions (included in -O3) compiler option.
  46    There are more restrictions to inlining: If inlined functions
  47    call other functions, the already inlined instructions are
  48    counted and once the recursive inline limit (see
  49    "max-inline-insns" parameter) is exceeded, the acceptable size
  50    gets decreased.  */
  51 DEFPARAM (PARAM_MAX_INLINE_INSNS_SINGLE,
  52           "max-inline-insns-single",
  53           "The maximum number of instructions in a single function eligible for inlining",
  54           500)
  55
  56 /* The single function inlining limit for functions that are
  57    inlined by virtue of -finline-functions (-O3).
  58    This limit should be chosen to be below or equal to the limit
  59    that is applied to functions marked inlined (or defined in the
  60    class declaration in C++) given by the "max-inline-insns-single"
  61    parameter.
  62    The default value is 150.  */
  63 DEFPARAM (PARAM_MAX_INLINE_INSNS_AUTO,
  64           "max-inline-insns-auto",
  65           "The maximum number of instructions when automatically inlining",
  66           120)
  67
  68 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE,
  69           "max-inline-insns-recursive",
  70           "The maximum number of instructions inline function can grow to via recursive inlining",
  71           500)
  72
  73 DEFPARAM (PARAM_MAX_INLINE_INSNS_RECURSIVE_AUTO,
  74           "max-inline-insns-recursive-auto",
  75           "The maximum number of instructions non-inline function can grow to via recursive inlining",
  76           500)
  77
  78 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH,
  79           "max-inline-recursive-depth",
  80           "The maximum depth of recursive inlining for inline functions",
  81           8)
  82
  83 DEFPARAM (PARAM_MAX_INLINE_RECURSIVE_DEPTH_AUTO,
  84           "max-inline-recursive-depth-auto",
  85           "The maximum depth of recursive inlining for non-inline functions",
  86           8)
  87
  88 /* For languages that (still) use the RTL inliner, we can specify
  89    limits for the RTL inliner separately.
  90    The parameter here defines the maximum number of RTL instructions
  91    a function may have to be eligible for inlining in the RTL inliner.
  92    The default value is 600.  */
  93 DEFPARAM (PARAM_MAX_INLINE_INSNS_RTL,
  94           "max-inline-insns-rtl",
  95           "The maximum number of instructions for the RTL inliner",
  96           600)
  97
  98 /* The maximum number of instructions to consider when looking for an
  99    instruction to fill a delay slot.  If more than this arbitrary
 100    number of instructions is searched, the time savings from filling
 101    the delay slot will be minimal so stop searching.  Increasing
 102    values mean more aggressive optimization, making the compile time
 103    increase with probably small improvement in executable run time.  */
 104 DEFPARAM (PARAM_MAX_DELAY_SLOT_INSN_SEARCH,
 105           "max-delay-slot-insn-search",
 106           "The maximum number of instructions to consider to fill a delay slot",
 107           100)
 108
 109 /* When trying to fill delay slots, the maximum number of instructions
 110    to consider when searching for a block with valid live register
 111    information.  Increasing this arbitrarily chosen value means more
 112    aggressive optimization, increasing the compile time.  This
 113    parameter should be removed when the delay slot code is rewritten
 114    to maintain the control-flow graph.  */
 115 DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
 116          "max-delay-slot-live-search",
 117          "The maximum number of instructions to consider to find accurate live register information",
 118          333)
 119
 120 /* This parameter limits the number of branch elements that the
 121    scheduler will track anti-dependencies through without resetting
 122    the tracking mechanism.  Large functions with few calls or barriers
 123    can generate lists containing many 1000's of dependencies.  Generally
 124    the compiler either uses all available memory, or runs for far too long.  */
 125 DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
 126          "max-pending-list-length",
 127          "The maximum length of scheduling's pending operations list",
 128          32)
 129
 130 DEFPARAM(PARAM_LARGE_FUNCTION_INSNS,
 131          "large-function-insns",
 132          "The size of function body to be considered large",
 133          3000)
 134 DEFPARAM(PARAM_LARGE_FUNCTION_GROWTH,
 135          "large-function-growth",
 136          "Maximal growth due to inlining of large function (in percent)",
 137          100)
 138 DEFPARAM(PARAM_INLINE_UNIT_GROWTH,
 139          "inline-unit-growth",
 140          "how much can given compilation unit grow because of the inlining (in percent)",
 141          50)
 142
 143 /* The GCSE optimization will be disabled if it would require
 144    significantly more memory than this value.  */
 145 DEFPARAM(PARAM_MAX_GCSE_MEMORY,
 146          "max-gcse-memory",
 147          "The maximum amount of memory to be allocated by GCSE",
 148          50 * 1024 * 1024)
 149 /* The number of repetitions of copy/const prop and PRE to run.  */
 150 DEFPARAM(PARAM_MAX_GCSE_PASSES,
 151         "max-gcse-passes",
 152         "The maximum number of passes to make when doing GCSE",
 153         1)
 154 /* This is the threshold ratio when to perform partial redundancy
 155    elimination after reload. We perform partial redundancy elimination
 156    when the following holds:
 157    (Redundant load execution count)
 158    ------------------------------- >= GCSE_AFTER_RELOAD_PARTIAL_FRACTION
 159    (Added loads execution count)                                          */
 160 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_PARTIAL_FRACTION,
 161         "gcse-after-reload-partial-fraction",
 162         "The threshold ratio for performing partial redundancy elimination \
 163          after reload.",
 164         3)
 165 /* This is the threshold ratio of the critical edges execution count compared to
 166    the redundant loads execution count that permits performing the load
 167    redundancy elimination in gcse after reload.  */
 168 DEFPARAM(PARAM_GCSE_AFTER_RELOAD_CRITICAL_FRACTION,
 169         "gcse-after-reload-critical-fraction",
 170         "The threshold ratio of critical edges execution count that permit \
 171          performing redundancy elimination after reload.",
 172         10)
 173 /* This parameter limits the number of insns in a loop that will be unrolled,
 174    and by how much the loop is unrolled.
 175
 176    This limit should be at most half of the peeling limits:  loop unroller
 177    decides to not unroll loops that iterate fewer than 2*number of allowed
 178    unrollings and thus we would have loops that are neither peeled or unrolled
 179    otherwise.  */
 180 DEFPARAM(PARAM_MAX_UNROLLED_INSNS,
 181          "max-unrolled-insns",
 182          "The maximum number of instructions to consider to unroll in a loop",
 183          200)
 184 /* This parameter limits how many times the loop is unrolled depending
 185    on number of insns really executed in each iteration.  */
 186 DEFPARAM(PARAM_MAX_AVERAGE_UNROLLED_INSNS,
 187          "max-average-unrolled-insns",
 188          "The maximum number of instructions to consider to unroll in a loop on average",
 189          80)
 190 /* The maximum number of unrollings of a single loop.  */
 191 DEFPARAM(PARAM_MAX_UNROLL_TIMES,
 192         "max-unroll-times",
 193         "The maximum number of unrollings of a single loop",
 194         8)
 195 /* The maximum number of insns of a peeled loop.  */
 196 DEFPARAM(PARAM_MAX_PEELED_INSNS,
 197         "max-peeled-insns",
 198         "The maximum number of insns of a peeled loop",
 199         400)
 200 /* The maximum number of peelings of a single loop.  */
 201 DEFPARAM(PARAM_MAX_PEEL_TIMES,
 202         "max-peel-times",
 203         "The maximum number of peelings of a single loop",
 204         16)
 205 /* The maximum number of insns of a peeled loop.  */
 206 DEFPARAM(PARAM_MAX_COMPLETELY_PEELED_INSNS,
 207         "max-completely-peeled-insns",
 208         "The maximum number of insns of a completely peeled loop",
 209         400)
 210 /* The maximum number of peelings of a single loop that is peeled completely.  */
 211 DEFPARAM(PARAM_MAX_COMPLETELY_PEEL_TIMES,
 212         "max-completely-peel-times",
 213         "The maximum number of peelings of a single loop that is peeled completely",
 214         16)
 215 /* The maximum number of insns of a peeled loop that rolls only once.  */
 216 DEFPARAM(PARAM_MAX_ONCE_PEELED_INSNS,
 217         "max-once-peeled-insns",
 218         "The maximum number of insns of a peeled loop that rolls only once",
 219         400)
 220
 221 /* The maximum number of insns of an unswitched loop.  */
 222 DEFPARAM(PARAM_MAX_UNSWITCH_INSNS,
 223         "max-unswitch-insns",
 224         "The maximum number of insns of an unswitched loop",
 225         50)
 226 /* The maximum level of recursion in unswitch_single_loop.  */
 227 DEFPARAM(PARAM_MAX_UNSWITCH_LEVEL,
 228         "max-unswitch-level",
 229         "The maximum number of unswitchings in a single loop",
 230         3)
 231
 232 /* The maximum number of iterations of a loop the brute force algorithm
 233    for analysis of # of iterations of the loop tries to evaluate.  */
 234 DEFPARAM(PARAM_MAX_ITERATIONS_TO_TRACK,
 235         "max-iterations-to-track",
 236         "Bound on the number of iterations the brute force # of iterations \
 237          analysis algorithm evaluates",
 238         1000)
 239
 240 DEFPARAM(PARAM_MAX_SMS_LOOP_NUMBER,
 241          "max-sms-loop-number",
 242          "Maximum number of loops to perform swing modulo scheduling on \
 243           (mainly for debugging)",
 244          -1)
 245
 246 /* This parameter is used to tune SMS MAX II calculations.  */
 247 DEFPARAM(PARAM_SMS_MAX_II_FACTOR,
 248          "sms-max-ii-factor",
 249          "A factor for tuning the upper bound that swing modulo scheduler uses \
 250           for scheduling a loop",
 251          100)
 252 DEFPARAM(PARAM_SMS_DFA_HISTORY,
 253          "sms-dfa-history",
 254          "The number of cycles the swing modulo scheduler considers when \
 255           checking conflicts using DFA",
 256          0)
 257 DEFPARAM(PARAM_SMS_LOOP_AVERAGE_COUNT_THRESHOLD,
 258          "sms-loop-average-count-threshold",
 259          "A threshold on the average loop count considered by the swing modulo \
 260           scheduler",
 261          0)
 262
 263 DEFPARAM(HOT_BB_COUNT_FRACTION,
 264          "hot-bb-count-fraction",
 265          "Select fraction of the maximal count of repetitions of basic block in \
 266 program given basic block needs to have to be considered hot",
 267          10000)
 268 DEFPARAM(HOT_BB_FREQUENCY_FRACTION,
 269          "hot-bb-frequency-fraction",
 270          "Select fraction of the maximal frequency of executions of basic \
 271 block in function given basic block needs to have to be considered hot",
 272          1000)
 273 DEFPARAM(TRACER_DYNAMIC_COVERAGE_FEEDBACK,
 274          "tracer-dynamic-coverage-feedback",
 275          "The percentage of function, weighted by execution frequency, that \
 276 must be covered by trace formation. Used when profile feedback is available",
 277          95)
 278 DEFPARAM(TRACER_DYNAMIC_COVERAGE,
 279          "tracer-dynamic-coverage",
 280          "The percentage of function, weighted by execution frequency, that \
 281 must be covered by trace formation. Used when profile feedback is not available",
 282          75)
 283 DEFPARAM(TRACER_MAX_CODE_GROWTH,
 284          "tracer-max-code-growth",
 285          "Maximal code growth caused by tail duplication (in percent)",
 286          100)
 287 DEFPARAM(TRACER_MIN_BRANCH_RATIO,
 288          "tracer-min-branch-ratio",
 289          "Stop reverse growth if the reverse probability of best edge is less \
 290 than this threshold (in percent)",
 291          10)
 292 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK,
 293          "tracer-min-branch-probability-feedback",
 294          "Stop forward growth if the probability of best edge is less than \
 295 this threshold (in percent). Used when profile feedback is available",
 296          80)
 297 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY,
 298          "tracer-min-branch-probability",
 299          "Stop forward growth if the probability of best edge is less than \
 300 this threshold (in percent). Used when profile feedback is not available",
 301          50)
 302
 303 /* The maximum number of incoming edges to consider for crossjumping.  */
 304 DEFPARAM(PARAM_MAX_CROSSJUMP_EDGES,
 305          "max-crossjump-edges",
 306          "The maximum number of incoming edges to consider for crossjumping",
 307          100)
 308
 309 /* The minimum number of matching instructions to consider for crossjumping.  */
 310 DEFPARAM(PARAM_MIN_CROSSJUMP_INSNS,
 311      "min-crossjump-insns",
 312      "The minimum number of matching instructions to consider for crossjumping",
 313      5)
 314
 315 /* The maximum length of path considered in cse.  */
 316 DEFPARAM(PARAM_MAX_CSE_PATH_LENGTH,
 317          "max-cse-path-length",
 318          "The maximum length of path considered in cse",
 319          10)
 320
 321 /* The cost of expression in loop invariant motion that is considered
 322    expensive.  */
 323 DEFPARAM(PARAM_LIM_EXPENSIVE,
 324          "lim-expensive",
 325          "The minimum cost of an expensive expression in the loop invariant motion",
 326          20)
 327
 328 /* Bound on number of candidates for induction variables below that
 329    all candidates are considered for each use in induction variable
 330    optimizations.  */
 331
 332 DEFPARAM(PARAM_IV_CONSIDER_ALL_CANDIDATES_BOUND,
 333          "iv-consider-all-candidates-bound",
 334          "Bound on number of candidates below that all candidates are considered in iv optimizations",
 335          30)
 336
 337 /* The induction variable optimizations give up on loops that contain more
 338    induction variable uses.  */
 339
 340 DEFPARAM(PARAM_IV_MAX_CONSIDERED_USES,
 341          "iv-max-considered-uses",
 342          "Bound on number of iv uses in loop optimized in iv optimizations",
 343          250)
 344
 345 /* The product of the next two is used to decide whether or not to
 346    use .GLOBAL_VAR.  See tree-dfa.c.  */
 347 DEFPARAM(PARAM_GLOBAL_VAR_THRESHOLD,
 348         "global-var-threshold",
 349         "Given N calls and V call-clobbered vars in a function.  Use .GLOBAL_VAR if NxV is larger than this limit",
 350         500000)
 351
 352 DEFPARAM(PARAM_MAX_CSELIB_MEMORY_LOCATIONS,
 353          "max-cselib-memory-locations",
 354          "The maximum memory locations recorded by cselib",
 355          500)
 356
 357 #ifdef ENABLE_GC_ALWAYS_COLLECT
 358 # define GGC_MIN_EXPAND_DEFAULT 0
 359 # define GGC_MIN_HEAPSIZE_DEFAULT 0
 360 #else
 361 # define GGC_MIN_EXPAND_DEFAULT 30
 362 # define GGC_MIN_HEAPSIZE_DEFAULT 4096
 363 #endif
 364
 365 DEFPARAM(GGC_MIN_EXPAND,
 366          "ggc-min-expand",
 367          "Minimum heap expansion to trigger garbage collection, as \
 368 a percentage of the total size of the heap",
 369          GGC_MIN_EXPAND_DEFAULT)
 370
 371 DEFPARAM(GGC_MIN_HEAPSIZE,
 372          "ggc-min-heapsize",
 373          "Minimum heap size before we start collecting garbage, in kilobytes",
 374          GGC_MIN_HEAPSIZE_DEFAULT)
 375
 376 #undef GGC_MIN_EXPAND_DEFAULT
 377 #undef GGC_MIN_HEAPSIZE_DEFAULT
 378
 379 DEFPARAM(PARAM_MAX_RELOAD_SEARCH_INSNS,
 380          "max-reload-search-insns",
 381          "The maximum number of instructions to search backward when looking for equivalent reload",
 382          100)
 383
 384 DEFPARAM(PARAM_MAX_ALIASED_VOPS,
 385          "max-aliased-vops",
 386          "The maximum number of virtual operands allowed to represent aliases before triggering alias grouping.",
 387          500)
 388
 389 DEFPARAM(PARAM_MAX_SCHED_REGION_BLOCKS,
 390          "max-sched-region-blocks",
 391          "The maximum number of blocks in a region to be considered for interblock scheduling",
 392          10)
 393
 394 DEFPARAM(PARAM_MAX_SCHED_REGION_INSNS,
 395          "max-sched-region-insns",
 396          "The maximum number of insns in a region to be considered for interblock scheduling",
 397          100)
 398
 399 /* INTEGER_CST nodes are shared for values [{-1,0} .. N) for
 400    {signed,unsigned} integral types.  This determines N.
 401    Experimentation shows 256 to be a good value.  */
 402 DEFPARAM (PARAM_INTEGER_SHARE_LIMIT,
 403           "integer-share-limit",
 404           "The upper bound for sharing integer constants",
 405           256)
 406
 407 /*
 408 Local variables:
 409 mode:c
 410 End: */