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