llvm/utils/bisect-skip-count

#!/usr/bin/env python3
# This script is used to bisect skip and count arguments for --debug-counter.
# It is similar to bisect, except it understands how to increase skip and decrease count
#
# Typical usage:
#
# bisect-skip-count bisect-command.sh "%(skip)d" "%(count)d" 2>&1 | tee bisect.out
#
# bisect-command.sh is something like this:
# #! /bin/bash
#
# skip=$1
# count=$2
#
# opt -debug-counter=my-counter-skip=${skip},my-counter-count=${count}
# ... Test output of opt and exit zero for pass, non-zero for fail
#
# Examine bisect.out to look for "Last good skip" and "Last good
# count" to find the values of the counter that produce a passing
# result.  Incrementing the last good count by one or decrementing the
# last good skip by one should produce a failure.
#
from __future__ import print_function
import os
import sys
import argparse
# This is for timeout support. Use the recommended way of import.
# We do timeouts because when doing, execution testing, we have a habit
# of finding variants that infinite loop
if os.name == 'posix' and sys.version_info[0] < 3:
  import subprocess32 as subprocess
else:
  import subprocess
parser = argparse.ArgumentParser()

parser.add_argument('--skipstart', type=int, default=0)
parser.add_argument('--skipend', type=int, default=(1 << 32))
parser.add_argument('--countstart', type=int, default=0)
parser.add_argument('--countend', type=int, default=(1 << 32))
parser.add_argument('--timeout', type=int, default=None)
# Use shell support if you need to use complex shell expressions in your command
parser.add_argument('--shell', type=bool, default=False)
parser.add_argument('command', nargs='+')

args = parser.parse_args()

start = args.skipstart
end = args.skipend

print("Bisect of Skip starting!")
print("Start: %d" % start)
print("End: %d" % end)

last = None
while start != end and start != end-1:
    count = start + (end - start)//2
    print("Visiting Skip: %d with (Start, End) = (%d,%d)" % (count, start, end))
    cmd = [x % {'skip':count, 'count':-1} for x in args.command]
    print(cmd)
    try:
        result = subprocess.call(cmd, shell=args.shell, timeout=args.timeout)
        if result == 0:
           print("    PASSES! Setting end to count")
           end = count
        else:
           print("    FAILS! Setting start to count")
           start = count
    except:
        print(" TIMEOUT, setting end to count")
        end = count
firstcount = start
print("Last good skip: %d" % start)
start = args.countstart
end = args.countend
print("Bisect of Count starting!")
print("Start: %d" % start)
print("End: %d" % end)
while start != end and start != end-1:
    count = start + (end - start)//2
    print("Visiting Count: %d with (Start, End) = (%d,%d)" % (count, start, end))
    cmd = [x % {'count':count, 'skip':firstcount } for x in args.command]
    print(cmd)
    try:
        result = subprocess.call(cmd, shell=args.shell, timeout=args.timeout)
        if result == 0:
           print("    PASSES! Setting start to count")
           start = count
        else:
           print("    FAILS! Setting end to count")
           end = count
    except:
        print(" TIMEOUT, setting start to count")
        start = count

print("Last good count: %d" % start)