* src/ios.cc [_GLIBCPP_HAVE_UNISTD_H]: Include unistd.h.

[thirdparty/gcc.git] / gcc / params.def

/* params.def - Run-time parameters.
   Copyright (C) 2001 Free Software Foundation, Inc.
   Written by Mark Mitchell <mark@codesourcery.com>.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.

*/

/* This file contains definitions for language-independent
   parameters.  The DEFPARAM macro takes 4 arguments:

     - The enumeral corresponding to this parameter.

     - The name that can be used to set this parameter using the 
       command-line option `--param <name>=<value>'.

     - A help string explaining how the parameter is used.

     - A default value for the parameter.

   Be sure to add an entry to invoke.texi summarizing the parameter.  */

/* The single function inlining limit. This is the maximum size
   of a function counted in internal gcc instructions (not in
   real machine instructions) that is eligible for inlining
   by the tree inliner.
   The default value is 300.
   Only functions marked inline (or methods defined in the class
   definition for C++) are affected by this, unless you set the
   -finline-functions (included in -O3) compiler option.
   There are more restrictions to inlining: If inlined functions
   call other functions, the already inlined instructions are
   counted and once the recursive inline limit (see 
   "max-inline-insns" parameter) is exceeded, the acceptable size
   gets decreased.  */
DEFPARAM (PARAM_MAX_INLINE_INSNS_SINGLE,
	  "max-inline-insns-single",
	  "The maximum number of instructions in a single function eliglible for inlining",
	  300)

/* The repeated inlining limit. After this number of instructions 
   (in the internal gcc representation, not real machine instructions)
   got inlined by repeated inlining, gcc starts to decrease the maximum
   number of inlinable instructions in the tree inliner.
   This is done by a linear function, see "max-inline-slope" parameter.
   It is necessary in order to limit the compile-time resources, that 
   could otherwise become very high.
   It is recommended to set this value to twice the value of the single
   function limit (set by the "max-inline-insns-single" parameter) or
   higher. The default value is 600.
   Higher values mean that more inlining is done, resulting in
   better performance of the code, at the expense of higher 
   compile-time resource (time, memory) requirements and larger
   binaries.  
   This parameters also controls the maximum size of functions considered
   for inlining in the RTL inliner.  */
DEFPARAM (PARAM_MAX_INLINE_INSNS,
	  "max-inline-insns",
	  "The maximuem number of instructions by repeated inlining before gcc starts to throttle inlining",
	  600)

/* After the repeated inline limit has been exceeded (see
   "max-inline-insns" parameter), a linear function is used to
   decrease the size of single functions eligible for inlining.
   The slope of this linear function is given the negative
   reciprocal value (-1/x) of this parameter. 
   The default vlue is 32.
   This linear function is used until it falls below a minimum
   value specified by the "min-inline-insns" parameter.  */
DEFPARAM (PARAM_MAX_INLINE_SLOPE,
	  "max-inline-slope",
	  "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",
	  32)

/* When gcc has inlined so many instructions (by repeated
   inlining) that the throttling limits the inlining very much,
   inlining for very small functions is still desirable to
   achieve good runtime performance. The size of single functions 
   (measured in gcc instructions) which will still be eligible for 
   inlining then is given by this parameter. It defaults to 130.
   Only much later (after exceeding 128 times the recursive limit)
   inlining is cut down completely.  */
DEFPARAM (PARAM_MIN_INLINE_INSNS,
	  "min-inline-insns",
	  "The number of instructions in a single functions still eligible to inlining after a lot recursive inlining",
	  130)

/* The maximum number of instructions to consider when looking for an
   instruction to fill a delay slot.  If more than this arbitrary
   number of instructions is searched, the time savings from filling
   the delay slot will be minimal so stop searching.  Increasing
   values mean more aggressive optimization, making the compile time
   increase with probably small improvement in executable run time.  */
DEFPARAM (PARAM_MAX_DELAY_SLOT_INSN_SEARCH,
	  "max-delay-slot-insn-search",
	  "The maximum number of instructions to consider to fill a delay slot",
	  100)

/* When trying to fill delay slots, the maximum number of instructions
   to consider when searching for a block with valid live register
   information.  Increasing this arbitrarily chosen value means more
   aggressive optimization, increasing the compile time.  This
   parameter should be removed when the delay slot code is rewritten
   to maintain the control-flow graph.  */
DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
	 "max-delay-slot-live-search",
	 "The maximum number of instructions to consider to find accurate live register information",
	 333)

/* This parameter limits the number of branch elements that the 
   scheduler will track anti-dependencies through without resetting
   the tracking mechanism.  Large functions with few calls or barriers 
   can generate lists containing many 1000's of dependencies.  Generally 
   the compiler either uses all available memory, or runs for far too long.  */
DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
	 "max-pending-list-length",
	 "The maximum length of scheduling's pending operations list",
	 32)

/* The GCSE optimization will be disabled if it would require
   significantly more memory than this value.  */
DEFPARAM(PARAM_MAX_GCSE_MEMORY,
	 "max-gcse-memory",
	 "The maximum amount of memory to be allocated by GCSE",
	 50 * 1024 * 1024)
/* The number of repetitions of copy/const prop and PRE to run.  */
DEFPARAM(PARAM_MAX_GCSE_PASSES,
	"max-gcse-passes",
	"The maximum number of passes to make when doing GCSE",
	1)

/* This parameter limits the number of insns in a loop that will be unrolled,
   and by how much the loop is unrolled.  */
DEFPARAM(PARAM_MAX_UNROLLED_INSNS,
	 "max-unrolled-insns",
	 "The maximum number of instructions to consider to unroll in a loop",
	 100)

DEFPARAM(HOT_BB_COUNT_FRACTION,
	 "hot-bb-count-fraction",
	 "Select fraction of the maximal count of repetitions of basic block in \
program given basic block needs to have to be considered hot",
	 10000)
DEFPARAM(HOT_BB_FREQUENCY_FRACTION,
	 "hot-bb-frequency-fraction",
	 "Select fraction of the maximal frequency of executions of basic \
block in function given basic block needs to have to be considered hot",
	 1000)
DEFPARAM(TRACER_DYNAMIC_COVERAGE_FEEDBACK,
	 "tracer-dynamic-coverage-feedback",
	 "The percentage of function, weighted by execution frequency, that \
must be covered by trace formation. Used when profile feedback is available",
	 95)
DEFPARAM(TRACER_DYNAMIC_COVERAGE,
	 "tracer-dynamic-coverage",
	 "The percentage of function, weighted by execution frequency, that \
must be covered by trace formation. Used when profile feedback is not available",
	 75)
DEFPARAM(TRACER_MAX_CODE_GROWTH,
	 "tracer-max-code-growth",
	 "Maximal code growth caused by tail duplication (in percents)",
	 100)
DEFPARAM(TRACER_MIN_BRANCH_RATIO,
	 "tracer-min-branch-ratio",
	 "Stop reverse growth if the reverse probability of best edge is less \
than this threshold (in percents)",
	 10)
DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK,
	 "tracer-min-branch-probability-feedback",
	 "Stop forward growth if the probability of best edge is less than \
this threshold (in percents). Used when profile feedback is available",
	 30)
DEFPARAM(TRACER_MIN_BRANCH_PROBABILITY,
	 "tracer-min-branch-probability",
	 "Stop forward growth if the probability of best edge is less than \
this threshold (in percents). Used when profile feedback is not available",
	 50)

#ifdef ENABLE_GC_ALWAYS_COLLECT
# define GGC_MIN_EXPAND_DEFAULT 0
#else
# define GGC_MIN_EXPAND_DEFAULT 30
#endif

DEFPARAM(GGC_MIN_EXPAND,
	 "ggc-min-expand",
	 "Minimum heap expansion to trigger garbage collection, as \
a percentage of the total size of the heap.",
	 GGC_MIN_EXPAND_DEFAULT)

#undef GGC_MIN_EXPAND_DEFAULT

DEFPARAM(GGC_MIN_HEAPSIZE,
	 "ggc-min-heapsize",
	 "Minimum heap size before we start collecting garbage, in kilobytes.",
	 4096)

/*
Local variables:
mode:c
End: */