gcc/params.def

   1 /* params.def - Run-time parameters.
   2    Copyright (C) 2001, 2002 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 100.
  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 100.  */
  63 DEFPARAM (PARAM_MAX_INLINE_INSNS_AUTO,
  64           "max-inline-insns-auto",
  65           "The maximum number of instructions when automatically inlining",
  66           150)
  67
  68 /* The repeated inlining limit.  After this number of instructions
  69    (in the internal gcc representation, not real machine instructions)
  70    got inlined by repeated inlining, gcc starts to decrease the maximum
  71    number of inlinable instructions in the tree inliner.
  72    This is done by a linear function, see "max-inline-slope" parameter.
  73    It is necessary in order to limit the compile-time resources, that
  74    could otherwise become very high.
  75    It is recommended to set this value to twice the value of the single
  76    function limit (set by the "max-inline-insns-single" parameter) or
  77    higher.  The default value is 200.
  78    Higher values mean that more inlining is done, resulting in
  79    better performance of the code, at the expense of higher
  80    compile-time resource (time, memory) requirements and larger
  81    binaries.  */
  82 DEFPARAM (PARAM_MAX_INLINE_INSNS,
  83           "max-inline-insns",
  84           "The maximum number of instructions by repeated inlining before gcc starts to throttle inlining",
  85           200)
  86
  87 /* After the repeated inline limit has been exceeded (see
  88    "max-inline-insns" parameter), a linear function is used to
  89    decrease the size of single functions eligible for inlining.
  90    The slope of this linear function is given the negative
  91    reciprocal value (-1/x) of this parameter.
  92    The default value is 32.
  93    This linear function is used until it falls below a minimum
  94    value specified by the "min-inline-insns" parameter.  */
  95 DEFPARAM (PARAM_MAX_INLINE_SLOPE,
  96           "max-inline-slope",
  97           "The slope of the linear function throttling inlining after the recursive inlining limit has been reached is given by the negative reciprocal value of this parameter",
  98           32)
  99
 100 /* When gcc has inlined so many instructions (by repeated
 101    inlining) that the throttling limits the inlining very much,
 102    inlining for very small functions is still desirable to
 103    achieve good runtime performance.  The size of single functions
 104    (measured in gcc instructions) which will still be eligible for
 105    inlining then is given by this parameter.  It defaults to 130.
 106    Only much later (after exceeding 128 times the recursive limit)
 107    inlining is cut down completely.  */
 108 DEFPARAM (PARAM_MIN_INLINE_INSNS,
 109           "min-inline-insns",
 110           "The number of instructions in a single functions still eligible to inlining after a lot recursive inlining",
 111           10)
 112
 113 /* For languages that (still) use the RTL inliner, we can specify
 114    limits for the RTL inliner separately.
 115    The parameter here defines the maximum number of RTL instructions
 116    a function may have to be eligible for inlining in the RTL inliner.
 117    The default value is 600.  */
 118 DEFPARAM (PARAM_MAX_INLINE_INSNS_RTL,
 119           "max-inline-insns-rtl",
 120           "The maximum number of instructions for the RTL inliner",
 121           600)
 122
 123 /* The maximum number of instructions to consider when looking for an
 124    instruction to fill a delay slot.  If more than this arbitrary
 125    number of instructions is searched, the time savings from filling
 126    the delay slot will be minimal so stop searching.  Increasing
 127    values mean more aggressive optimization, making the compile time
 128    increase with probably small improvement in executable run time.  */
 129 DEFPARAM (PARAM_MAX_DELAY_SLOT_INSN_SEARCH,
 130           "max-delay-slot-insn-search",
 131           "The maximum number of instructions to consider to fill a delay slot",
 132           100)
 133
 134 /* When trying to fill delay slots, the maximum number of instructions
 135    to consider when searching for a block with valid live register
 136    information.  Increasing this arbitrarily chosen value means more
 137    aggressive optimization, increasing the compile time.  This
 138    parameter should be removed when the delay slot code is rewritten
 139    to maintain the control-flow graph.  */
 140 DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
 141          "max-delay-slot-live-search",
 142          "The maximum number of instructions to consider to find accurate live register information",
 143          333)
 144
 145 /* This parameter limits the number of branch elements that the
 146    scheduler will track anti-dependencies through without resetting
 147    the tracking mechanism.  Large functions with few calls or barriers
 148    can generate lists containing many 1000's of dependencies.  Generally
 149    the compiler either uses all available memory, or runs for far too long.  */
 150 DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
 151          "max-pending-list-length",
 152          "The maximum length of scheduling's pending operations list",
 153          32)
 154
 155 DEFPARAM(PARAM_LARGE_FUNCTION_INSNS,
 156          "large-function-insns",
 157          "The size of function body to be considered large",
 158          10000)
 159 DEFPARAM(PARAM_LARGE_FUNCTION_GROWTH,
 160          "large-function-growth",
 161          "Maximal growth due to inlining of large function (in percent)",
 162          100)
 163 DEFPARAM(PARAM_INLINE_UNIT_GROWTH,
 164          "inline-unit-growth",
 165          "how much can given compilation unit grow because of the inlining (in percent)",
 166          50)
 167
 168 /* The GCSE optimization will be disabled if it would require
 169    significantly more memory than this value.  */
 170 DEFPARAM(PARAM_MAX_GCSE_MEMORY,
 171          "max-gcse-memory",
 172          "The maximum amount of memory to be allocated by GCSE",
 173          50 * 1024 * 1024)
 174 /* The number of repetitions of copy/const prop and PRE to run.  */
 175 DEFPARAM(PARAM_MAX_GCSE_PASSES,
 176         "max-gcse-passes",
 177         "The maximum number of passes to make when doing GCSE",
 178         1)
 179
 180 /* This parameter limits the number of insns in a loop that will be unrolled,
 181    and by how much the loop is unrolled.  */
 182 DEFPARAM(PARAM_MAX_UNROLLED_INSNS,
 183          "max-unrolled-insns",
 184          "The maximum number of instructions to consider to unroll in a loop",
 185          200)
 186 /* This parameter limits how many times the loop is unrolled depending
 187    on number of insns really executed in each iteration.  */
 188 DEFPARAM(PARAM_MAX_AVERAGE_UNROLLED_INSNS,
 189          "max-average-unrolled-insns",
 190          "The maximum number of instructions to consider to unroll in a loop on average",
 191          80)
 192 /* The maximum number of unrollings of a single loop.  */
 193 DEFPARAM(PARAM_MAX_UNROLL_TIMES,
 194         "max-unroll-times",
 195         "The maximum number of unrollings of a single loop",
 196         8)
 197 /* The maximum number of insns of a peeled loop.  */
 198 DEFPARAM(PARAM_MAX_PEELED_INSNS,
 199         "max-peeled-insns",
 200         "The maximum number of insns of a peeled loop",
 201         120)
 202 /* The maximum number of peelings of a single loop.  */
 203 DEFPARAM(PARAM_MAX_PEEL_TIMES,
 204         "max-peel-times",
 205         "The maximum number of peelings of a single loop",
 206         16)
 207 /* The maximum number of insns of a peeled loop.  */
 208 DEFPARAM(PARAM_MAX_COMPLETELY_PEELED_INSNS,
 209         "max-completely-peeled-insns",
 210         "The maximum number of insns of a completely peeled loop",
 211         120)
 212 /* The maximum number of peelings of a single loop that is peeled completely.  */
 213 DEFPARAM(PARAM_MAX_COMPLETELY_PEEL_TIMES,
 214         "max-completely-peel-times",
 215         "The maximum number of peelings of a single loop that is peeled completely",
 216         16)
 217 /* The maximum number of insns of a peeled loop that rolls only once.  */
 218 DEFPARAM(PARAM_MAX_ONCE_PEELED_INSNS,
 219         "max-once-peeled-insns",
 220         "The maximum number of insns of a peeled loop that rolls only once",
 221         200)
 222
 223 /* The maximum number of insns of an unswitched loop.  */
 224 DEFPARAM(PARAM_MAX_UNSWITCH_INSNS,
 225         "max-unswitch-insns",
 226         "The maximum number of insns of an unswitched loop",
 227         50)
 228 /* The maximum level of recursion in unswitch_single_loop.  */
 229 DEFPARAM(PARAM_MAX_UNSWITCH_LEVEL,
 230         "max-unswitch-level",
 231         "The maximum number of unswitchings in a single loop",
 232         3)
 233
 234 DEFPARAM(HOT_BB_COUNT_FRACTION,
 235          "hot-bb-count-fraction",
 236          "Select fraction of the maximal count of repetitions of basic block in \
 237 program given basic block needs to have to be considered hot",
 238          10000)
 239 DEFPARAM(HOT_BB_FREQUENCY_FRACTION,
 240          "hot-bb-frequency-fraction",
 241          "Select fraction of the maximal frequency of executions of basic \
 242 block in function given basic block needs to have to be considered hot",
 243          1000)
 244 DEFPARAM(TRACER_DYNAMIC_COVERAGE_FEEDBACK,
 245          "tracer-dynamic-coverage-feedback",
 246          "The percentage of function, weighted by execution frequency, that \
 247 must be covered by trace formation. Used when profile feedback is available",
 248          95)
 249 DEFPARAM(TRACER_DYNAMIC_COVERAGE,
 250          "tracer-dynamic-coverage",
 251          "The percentage of function, weighted by execution frequency, that \
 252 must be covered by trace formation. Used when profile feedback is not available",
 253          75)
 254 DEFPARAM(TRACER_MAX_CODE_GROWTH,
 255          "tracer-max-code-growth",
 256          "Maximal code growth caused by tail duplication (in percent)",
 257          100)
 258 DEFPARAM(TRACER_MIN_BRANCH_RATIO,
 259          "tracer-min-branch-ratio",
 260          "Stop reverse growth if the reverse probability of best edge is less \
 261 than this threshold (in percent)",
 262          10)
 263 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK,
 264          "tracer-min-branch-probability-feedback",
 265          "Stop forward growth if the probability of best edge is less than \
 266 this threshold (in percent). Used when profile feedback is available",
 267          80)
 268 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY,
 269          "tracer-min-branch-probability",
 270          "Stop forward growth if the probability of best edge is less than \
 271 this threshold (in percent). Used when profile feedback is not available",
 272          50)
 273
 274 /* The maximum number of incoming edges to consider for crossjumping.  */
 275 DEFPARAM(PARAM_MAX_CROSSJUMP_EDGES,
 276          "max-crossjump-edges",
 277          "The maximum number of incoming edges to consider for crossjumping",
 278          100)
 279
 280 /* The maximum length of path considered in cse.  */
 281 DEFPARAM(PARAM_MAX_CSE_PATH_LENGTH,
 282          "max-cse-path-length",
 283          "The maximum length of path considered in cse",
 284          10)
 285
 286 #ifdef ENABLE_GC_ALWAYS_COLLECT
 287 # define GGC_MIN_EXPAND_DEFAULT 0
 288 # define GGC_MIN_HEAPSIZE_DEFAULT 0
 289 #else
 290 # define GGC_MIN_EXPAND_DEFAULT 30
 291 # define GGC_MIN_HEAPSIZE_DEFAULT 4096
 292 #endif
 293
 294 DEFPARAM(GGC_MIN_EXPAND,
 295          "ggc-min-expand",
 296          "Minimum heap expansion to trigger garbage collection, as \
 297 a percentage of the total size of the heap",
 298          GGC_MIN_EXPAND_DEFAULT)
 299
 300 DEFPARAM(GGC_MIN_HEAPSIZE,
 301          "ggc-min-heapsize",
 302          "Minimum heap size before we start collecting garbage, in kilobytes",
 303          GGC_MIN_HEAPSIZE_DEFAULT)
 304
 305 #undef GGC_MIN_EXPAND_DEFAULT
 306 #undef GGC_MIN_HEAPSIZE_DEFAULT
 307
 308 /*
 309 Local variables:
 310 mode:c
 311 End: */