88617fe425
* analyze_brprob.py: If there's no loop, do not calculate average number of loop iterations. From-SVN: r238590
183 lines
7.0 KiB
Python
Executable File
183 lines
7.0 KiB
Python
Executable File
#!/usr/bin/env python3
|
|
#
|
|
# Script to analyze results of our branch prediction heuristics
|
|
#
|
|
# 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 3, 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 COPYING3. If not see
|
|
# <http://www.gnu.org/licenses/>. */
|
|
#
|
|
#
|
|
#
|
|
# This script is used to calculate two basic properties of the branch prediction
|
|
# heuristics - coverage and hitrate. Coverage is number of executions
|
|
# of a given branch matched by the heuristics and hitrate is probability
|
|
# that once branch is predicted as taken it is really taken.
|
|
#
|
|
# These values are useful to determine the quality of given heuristics.
|
|
# Hitrate may be directly used in predict.def.
|
|
#
|
|
# Usage:
|
|
# Step 1: Compile and profile your program. You need to use -fprofile-generate
|
|
# flag to get the profiles.
|
|
# Step 2: Make a reference run of the intrumented application.
|
|
# Step 3: Compile the program with collected profile and dump IPA profiles
|
|
# (-fprofile-use -fdump-ipa-profile-details)
|
|
# Step 4: Collect all generated dump files:
|
|
# find . -name '*.profile' | xargs cat > dump_file
|
|
# Step 5: Run the script:
|
|
# ./analyze_brprob.py dump_file
|
|
# and read results. Basically the following table is printed:
|
|
#
|
|
# HEURISTICS BRANCHES (REL) HITRATE COVERAGE (REL)
|
|
# early return (on trees) 3 0.2% 35.83% / 93.64% 66360 0.0%
|
|
# guess loop iv compare 8 0.6% 53.35% / 53.73% 11183344 0.0%
|
|
# call 18 1.4% 31.95% / 69.95% 51880179 0.2%
|
|
# loop guard 23 1.8% 84.13% / 84.85% 13749065956 42.2%
|
|
# opcode values positive (on trees) 42 3.3% 15.71% / 84.81% 6771097902 20.8%
|
|
# opcode values nonequal (on trees) 226 17.6% 72.48% / 72.84% 844753864 2.6%
|
|
# loop exit 231 18.0% 86.97% / 86.98% 8952666897 27.5%
|
|
# loop iterations 239 18.6% 91.10% / 91.10% 3062707264 9.4%
|
|
# DS theory 281 21.9% 82.08% / 83.39% 7787264075 23.9%
|
|
# no prediction 293 22.9% 46.92% / 70.70% 2293267840 7.0%
|
|
# guessed loop iterations 313 24.4% 76.41% / 76.41% 10782750177 33.1%
|
|
# first match 708 55.2% 82.30% / 82.31% 22489588691 69.0%
|
|
# combined 1282 100.0% 79.76% / 81.75% 32570120606 100.0%
|
|
#
|
|
#
|
|
# The heuristics called "first match" is a heuristics used by GCC branch
|
|
# prediction pass and it predicts 55.2% branches correctly. As you can,
|
|
# the heuristics has very good covertage (69.05%). On the other hand,
|
|
# "opcode values nonequal (on trees)" heuristics has good hirate, but poor
|
|
# coverage.
|
|
|
|
import sys
|
|
import os
|
|
import re
|
|
import argparse
|
|
|
|
from math import *
|
|
|
|
def percentage(a, b):
|
|
return 100.0 * a / b
|
|
|
|
def average(values):
|
|
return 1.0 * sum(values) / len(values)
|
|
|
|
def average_cutoff(values, cut):
|
|
l = len(values)
|
|
skip = floor(l * cut / 2)
|
|
if skip > 0:
|
|
values.sort()
|
|
values = values[skip:-skip]
|
|
return average(values)
|
|
|
|
def median(values):
|
|
values.sort()
|
|
return values[int(len(values) / 2)]
|
|
|
|
class Summary:
|
|
def __init__(self, name):
|
|
self.name = name
|
|
self.branches = 0
|
|
self.count = 0
|
|
self.hits = 0
|
|
self.fits = 0
|
|
|
|
def get_hitrate(self):
|
|
return self.hits / self.count
|
|
|
|
def count_formatted(self):
|
|
v = self.count
|
|
for unit in ['','K','M','G','T','P','E','Z']:
|
|
if v < 1000:
|
|
return "%3.2f%s" % (v, unit)
|
|
v /= 1000.0
|
|
return "%.1f%s" % (v, 'Y')
|
|
|
|
class Profile:
|
|
def __init__(self, filename):
|
|
self.filename = filename
|
|
self.heuristics = {}
|
|
self.niter_vector = []
|
|
|
|
def add(self, name, prediction, count, hits):
|
|
if not name in self.heuristics:
|
|
self.heuristics[name] = Summary(name)
|
|
|
|
s = self.heuristics[name]
|
|
s.branches += 1
|
|
s.count += count
|
|
if prediction < 50:
|
|
hits = count - hits
|
|
s.hits += hits
|
|
s.fits += max(hits, count - hits)
|
|
|
|
def add_loop_niter(self, niter):
|
|
if niter > 0:
|
|
self.niter_vector.append(niter)
|
|
|
|
def branches_max(self):
|
|
return max([v.branches for k, v in self.heuristics.items()])
|
|
|
|
def count_max(self):
|
|
return max([v.count for k, v in self.heuristics.items()])
|
|
|
|
def dump(self, sorting):
|
|
sorter = lambda x: x[1].branches
|
|
if sorting == 'hitrate':
|
|
sorter = lambda x: x[1].get_hitrate()
|
|
elif sorting == 'coverage':
|
|
sorter = lambda x: x[1].count
|
|
|
|
print('%-40s %8s %6s %-16s %14s %8s %6s' % ('HEURISTICS', 'BRANCHES', '(REL)',
|
|
'HITRATE', 'COVERAGE', 'COVERAGE', '(REL)'))
|
|
for (k, v) in sorted(self.heuristics.items(), key = sorter):
|
|
print('%-40s %8i %5.1f%% %6.2f%% / %6.2f%% %14i %8s %5.1f%%' %
|
|
(k, v.branches, percentage(v.branches, self.branches_max ()),
|
|
percentage(v.hits, v.count), percentage(v.fits, v.count),
|
|
v.count, v.count_formatted(), percentage(v.count, self.count_max()) ))
|
|
|
|
if len(self.niter_vector) > 0:
|
|
print ('\nLoop count: %d' % len(self.niter_vector)),
|
|
print(' avg. # of iter: %.2f' % average(self.niter_vector))
|
|
print(' median # of iter: %.2f' % median(self.niter_vector))
|
|
for v in [1, 5, 10, 20, 30]:
|
|
cut = 0.01 * v
|
|
print(' avg. (%d%% cutoff) # of iter: %.2f' % (v, average_cutoff(self.niter_vector, cut)))
|
|
|
|
parser = argparse.ArgumentParser()
|
|
parser.add_argument('dump_file', metavar = 'dump_file', help = 'IPA profile dump file')
|
|
parser.add_argument('-s', '--sorting', dest = 'sorting', choices = ['branches', 'hitrate', 'coverage'], default = 'branches')
|
|
|
|
args = parser.parse_args()
|
|
|
|
profile = Profile(sys.argv[1])
|
|
r = re.compile(' (.*) heuristics( of edge [0-9]*->[0-9]*)?( \\(.*\\))?: (.*)%.*exec ([0-9]*) hit ([0-9]*)')
|
|
loop_niter_str = ';; profile-based iteration count: '
|
|
for l in open(args.dump_file).readlines():
|
|
m = r.match(l)
|
|
if m != None and m.group(3) == None:
|
|
name = m.group(1)
|
|
prediction = float(m.group(4))
|
|
count = int(m.group(5))
|
|
hits = int(m.group(6))
|
|
|
|
profile.add(name, prediction, count, hits)
|
|
elif l.startswith(loop_niter_str):
|
|
v = int(l[len(loop_niter_str):])
|
|
profile.add_loop_niter(v)
|
|
|
|
profile.dump(args.sorting)
|