* analyze_brprob: New file.
From-SVN: r43252
This commit is contained in:
parent
aa18f20e74
commit
17d6c819b2
@ -1,3 +1,7 @@
|
||||
Tue Jun 12 12:21:40 CEST 2001 Jan Hubicka <jh@suse.cz>
|
||||
|
||||
* analyze_brprob: New file.
|
||||
|
||||
2001-06-11 Mark Mitchell <mark@codesourcery.com>
|
||||
|
||||
* gcc_build: Output information about the commands used to
|
||||
|
149
contrib/analyze_brprob
Executable file
149
contrib/analyze_brprob
Executable file
@ -0,0 +1,149 @@
|
||||
#!/usr/bin/awk -f
|
||||
# Script to analyze experimental results of our branch prediction heursitics
|
||||
# Contributed by Jan Hubicka, SuSE inc.
|
||||
# Copyright (C) 2001 Free Software Foundation, Inc.
|
||||
#
|
||||
# This file is part of GNU CC.
|
||||
#
|
||||
# GNU CC 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.
|
||||
#
|
||||
# GNU CC 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 GNU CC; see the file COPYING. If not, write to
|
||||
# the Free Software Foundation, 59 Temple Place - Suite 330,
|
||||
# Boston, MA 02111-1307, USA.
|
||||
#
|
||||
#
|
||||
# This script is used to calculate two basic properties of the branch prediction
|
||||
# heursitics - coverage and hitrate. Coverage is number of executions of given
|
||||
# branch matched by the heuristics and hitrate is probability that once branch is
|
||||
# predicted as taken it is really taken.
|
||||
#
|
||||
# These values are usefull to determine quality of given heuristics and hitrate
|
||||
# may be directly used in predict.c.
|
||||
#
|
||||
# Usage:
|
||||
# step 1: compile and profile your program. You need to use -fprofile-arcs
|
||||
# flag to get the profiles
|
||||
# step 2: Generate log files. The information about given heuristics are
|
||||
# saved into *.life dumps. You need to pass -df swtich to compiler as well
|
||||
# as -fbranch-probabilities to get results of profiling noted in the dumps.
|
||||
# Ensure that there is no "Arc profiling: some edge counts were bad." warnings.
|
||||
# Keep the -fprofile-arcs switch to ensure that CFGs match.
|
||||
# step 3: Run this script to concatetation of all *.life files:
|
||||
# analyze_brprob `find . -name *.life`
|
||||
# the information is collected and print once all files are parsed. This
|
||||
# may take a while.
|
||||
# Note that script does use bc to perform long arithmetic.
|
||||
# step 4: Read the results. Basically following table is printed:
|
||||
# (this is just example from very early stages of branch prediction pass
|
||||
# development, so please don't take these numbers seriously)
|
||||
#
|
||||
#HEURISTICS BRANCHES (REL) HITRATE COVERAGE (REL)
|
||||
#opcode 2889 83.7% 94.96%/ 97.62% 7516383 75.3%
|
||||
#pointer 246 7.1% 99.69%/ 99.86% 118791 1.2%
|
||||
#loop header 449 13.0% 98.32%/ 99.07% 43553 0.4%
|
||||
#first match 3450 100.0% 89.92%/ 97.27% 9979782 100.0%
|
||||
#loop exit 924 26.8% 88.95%/ 95.58% 9026266 90.4%
|
||||
#error return 150 4.3% 64.48%/ 86.81% 453542 4.5%
|
||||
#call 803 23.3% 51.66%/ 98.61% 3614037 36.2%
|
||||
#loop branch 51 1.5% 99.26%/ 99.27% 26854 0.3%
|
||||
#noreturn call 951 27.6% 100.00%/100.00% 1759809 17.6%
|
||||
#
|
||||
# The heuristics called "first match" is heuristics used by gcc branch
|
||||
# prediction pass and it predicts 89.92% branches correctly.
|
||||
#
|
||||
# The quality of heuristics can be rated using both, coverage and hitrate
|
||||
# parameters. For example "loop branch" heuristics (predicting loopback edge
|
||||
# as taken) have both very high hitrate and coverage, so it is very usefull.
|
||||
# On the other hand, "exit block" heuristics (predicting exit edges as not
|
||||
# taken) have good hitrate, but poor coverage, so only 3 branches has been
|
||||
# predicted. The "loop header" heuristics have problem, since it tends to
|
||||
# misspredict.
|
||||
#
|
||||
# The implementation of this script is somewhat brute force. My awk skills
|
||||
# are limited.
|
||||
|
||||
function longeval(e)
|
||||
{
|
||||
e = "echo \"scale = 2 ;"e"\" | bc"
|
||||
e | getline res
|
||||
close (e)
|
||||
return res
|
||||
}
|
||||
|
||||
BEGIN {nnames = 0}
|
||||
|
||||
/^ .* heuristics: .*.$/ {
|
||||
name=$0
|
||||
sub (/^ /,"",name)
|
||||
sub (/ heuristics: .*.$/,"",name)
|
||||
if (!(name in branches))
|
||||
{
|
||||
names[nnames] = name
|
||||
branches[name]=0
|
||||
counts[name]=0
|
||||
hits[name]=0
|
||||
phits[name]=0
|
||||
nnames++
|
||||
}
|
||||
branches[name]+=1
|
||||
}
|
||||
|
||||
/^ .* heuristics: .*. exec [0-9]* hit [0-9]* (.*.)$/ {
|
||||
name=$0
|
||||
sub (/^ /,"",name)
|
||||
sub (/ heuristics: .*. exec [0-9]* hit [0-9]* (.*.)$/,"",name)
|
||||
pred=$0
|
||||
sub (/^ .* heuristics: /,"",pred)
|
||||
sub (/. exec [0-9]* hit [0-9]* (.*.)$/,"",pred)
|
||||
count=$0
|
||||
sub (/^ .* heuristics: .*. exec /,"",count)
|
||||
sub (/ hit [0-9]* (.*.)$/,"",count)
|
||||
hit=$0
|
||||
sub (/^ .* heuristics: .*. exec [0-9]* hit /,"",hit)
|
||||
sub (/ (.*.)$/,"",hit)
|
||||
|
||||
if (int(pred) < 50.0)
|
||||
{
|
||||
hit = count - hit;
|
||||
}
|
||||
counts[name]=counts[name] "+" count
|
||||
hits[name]=hits[name] "+" hit
|
||||
if (int (hit) < (int (count) / 2))
|
||||
hit = count - hit;
|
||||
phits[name]=phits[name] "+" hit
|
||||
|
||||
#BC crashes on long strings. Irritating.
|
||||
if (length(counts[name]) > 4000)
|
||||
{
|
||||
counts[name] = longeval (counts[name])
|
||||
hits[name] = longeval (hits[name])
|
||||
phits[name] = longeval (phits[name])
|
||||
}
|
||||
}
|
||||
END {
|
||||
# Heuristics called combined predicts just everything.
|
||||
maxcounts = longeval (counts["first match"])
|
||||
maxbranches = branches["first match"]
|
||||
max = names["firat match"]
|
||||
printf("HEURISTICS BRANCHES (REL) HITRATE COVERAGE (REL)\n")
|
||||
for (i = 0; i < nnames ; i++)
|
||||
{
|
||||
name = names[i]
|
||||
counts[name] = longeval (counts[name])
|
||||
printf ("%-27s %8i %5.1f%% %6s%%/%6s%% %12s %5.1f%%\n",
|
||||
name,
|
||||
branches[name], branches[name] * 100 / maxbranches,
|
||||
longeval ("("hits[name]") * 100 /(" counts[name]"-0.00001)"),
|
||||
longeval ("("phits[name]") * 100 /(" counts[name]"-0.00001)"),
|
||||
counts[name], longeval (counts[name]" * 100 / ("maxcounts"-0.00001)"))
|
||||
}
|
||||
}
|
Loading…
Reference in New Issue
Block a user