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 300.
  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 eliglible for inlining",
  54           300)
  55
  56 /* The repeated inlining limit. After this number of instructions
  57    (in the internal gcc representation, not real machine instructions)
  58    got inlined by repeated inlining, gcc starts to decrease the maximum
  59    number of inlinable instructions in the tree inliner.
  60    This is done by a linear function, see "max-inline-slope" parameter.
  61    It is necessary in order to limit the compile-time resources, that
  62    could otherwise become very high.
  63    It is recommended to set this value to twice the value of the single
  64    function limit (set by the "max-inline-insns-single" parameter) or
  65    higher. The default value is 600.
  66    Higher values mean that more inlining is done, resulting in
  67    better performance of the code, at the expense of higher
  68    compile-time resource (time, memory) requirements and larger
  69    binaries.
  70    This parameters also controls the maximum size of functions considered
  71    for inlining in the RTL inliner.  */
  72 DEFPARAM (PARAM_MAX_INLINE_INSNS,
  73           "max-inline-insns",
  74           "The maximuem number of instructions by repeated inlining before gcc starts to throttle inlining",
  75           600)
  76
  77 /* After the repeated inline limit has been exceeded (see
  78    "max-inline-insns" parameter), a linear function is used to
  79    decrease the size of single functions eligible for inlining.
  80    The slope of this linear function is given the negative
  81    reciprocal value (-1/x) of this parameter.
  82    The default vlue is 32.
  83    This linear function is used until it falls below a minimum
  84    value specified by the "min-inline-insns" parameter.  */
  85 DEFPARAM (PARAM_MAX_INLINE_SLOPE,
  86           "max-inline-slope",
  87           "The slope of the linear funtion throttling inlining after the recursive inlining limit has been reached is given by the negative reciprocal value of this parameter",
  88           32)
  89
  90 /* When gcc has inlined so many instructions (by repeated
  91    inlining) that the throttling limits the inlining very much,
  92    inlining for very small functions is still desirable to
  93    achieve good runtime performance. The size of single functions
  94    (measured in gcc instructions) which will still be eligible for
  95    inlining then is given by this parameter. It defaults to 130.
  96    Only much later (after exceeding 128 times the recursive limit)
  97    inlining is cut down completely.  */
  98 DEFPARAM (PARAM_MIN_INLINE_INSNS,
  99           "min-inline-insns",
 100           "The number of instructions in a single functions still eligible to inlining after a lot recursive inlining",
 101           130)
 102
 103 /* The maximum number of instructions to consider when looking for an
 104    instruction to fill a delay slot.  If more than this arbitrary
 105    number of instructions is searched, the time savings from filling
 106    the delay slot will be minimal so stop searching.  Increasing
 107    values mean more aggressive optimization, making the compile time
 108    increase with probably small improvement in executable run time.  */
 109 DEFPARAM (PARAM_MAX_DELAY_SLOT_INSN_SEARCH,
 110           "max-delay-slot-insn-search",
 111           "The maximum number of instructions to consider to fill a delay slot",
 112           100)
 113
 114 /* When trying to fill delay slots, the maximum number of instructions
 115    to consider when searching for a block with valid live register
 116    information.  Increasing this arbitrarily chosen value means more
 117    aggressive optimization, increasing the compile time.  This
 118    parameter should be removed when the delay slot code is rewritten
 119    to maintain the control-flow graph.  */
 120 DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
 121          "max-delay-slot-live-search",
 122          "The maximum number of instructions to consider to find accurate live register information",
 123          333)
 124
 125 /* This parameter limits the number of branch elements that the
 126    scheduler will track anti-dependencies through without resetting
 127    the tracking mechanism.  Large functions with few calls or barriers
 128    can generate lists containing many 1000's of dependencies.  Generally
 129    the compiler either uses all available memory, or runs for far too long.  */
 130 DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
 131          "max-pending-list-length",
 132          "The maximum length of scheduling's pending operations list",
 133          32)
 134
 135 /* The GCSE optimization will be disabled if it would require
 136    significantly more memory than this value.  */
 137 DEFPARAM(PARAM_MAX_GCSE_MEMORY,
 138          "max-gcse-memory",
 139          "The maximum amount of memory to be allocated by GCSE",
 140          50 * 1024 * 1024)
 141 /* The number of repetitions of copy/const prop and PRE to run.  */
 142 DEFPARAM(PARAM_MAX_GCSE_PASSES,
 143         "max-gcse-passes",
 144         "The maximum number of passes to make when doing GCSE",
 145         1)
 146
 147 /* This parameter limits the number of insns in a loop that will be unrolled,
 148    and by how much the loop is unrolled.  */
 149 DEFPARAM(PARAM_MAX_UNROLLED_INSNS,
 150          "max-unrolled-insns",
 151          "The maximum number of instructions to consider to unroll in a loop",
 152          100)
 153
 154 DEFPARAM(HOT_BB_COUNT_FRACTION,
 155          "hot-bb-count-fraction",
 156          "Select fraction of the maximal count of repetitions of basic block in \
 157 program given basic block needs to have to be considered hot",
 158          10000)
 159 DEFPARAM(HOT_BB_FREQUENCY_FRACTION,
 160          "hot-bb-frequency-fraction",
 161          "Select fraction of the maximal frequency of executions of basic \
 162 block in function given basic block needs to have to be considered hot",
 163          1000)
 164 DEFPARAM(TRACER_DYNAMIC_COVERAGE_FEEDBACK,
 165          "tracer-dynamic-coverage-feedback",
 166          "The percentage of function, weighted by execution frequency, that \
 167 must be covered by trace formation. Used when profile feedback is available",
 168          95)
 169 DEFPARAM(TRACER_DYNAMIC_COVERAGE,
 170          "tracer-dynamic-coverage",
 171          "The percentage of function, weighted by execution frequency, that \
 172 must be covered by trace formation. Used when profile feedback is not available",
 173          75)
 174 DEFPARAM(TRACER_MAX_CODE_GROWTH,
 175          "tracer-max-code-growth",
 176          "Maximal code growth caused by tail duplication (in percents)",
 177          100)
 178 DEFPARAM(TRACER_MIN_BRANCH_RATIO,
 179          "tracer-min-branch-ratio",
 180          "Stop reverse growth if the reverse probability of best edge is less \
 181 than this threshold (in percents)",
 182          10)
 183 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK,
 184          "tracer-min-branch-probability-feedback",
 185          "Stop forward growth if the probability of best edge is less than \
 186 this threshold (in percents). Used when profile feedback is available",
 187          80)
 188 DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY,
 189          "tracer-min-branch-probability",
 190          "Stop forward growth if the probability of best edge is less than \
 191 this threshold (in percents). Used when profile feedback is not available",
 192          50)
 193
 194 #ifdef ENABLE_GC_ALWAYS_COLLECT
 195 # define GGC_MIN_EXPAND_DEFAULT 0
 196 # define GGC_MIN_HEAPSIZE_DEFAULT 0
 197 #else
 198 # define GGC_MIN_EXPAND_DEFAULT 30
 199 # define GGC_MIN_HEAPSIZE_DEFAULT 4096
 200 #endif
 201
 202 DEFPARAM(GGC_MIN_EXPAND,
 203          "ggc-min-expand",
 204          "Minimum heap expansion to trigger garbage collection, as \
 205 a percentage of the total size of the heap.",
 206          GGC_MIN_EXPAND_DEFAULT)
 207
 208 DEFPARAM(GGC_MIN_HEAPSIZE,
 209          "ggc-min-heapsize",
 210          "Minimum heap size before we start collecting garbage, in kilobytes.",
 211          GGC_MIN_HEAPSIZE_DEFAULT)
 212
 213 #undef GGC_MIN_EXPAND_DEFAULT
 214 #undef GGC_MIN_HEAPSIZE_DEFAULT
 215
 216 /*
 217 Local variables:
 218 mode:c
 219 End: */