Add a small utility called bisect that enables commandline bisecting on a counter.

This is something that I have found to be very useful in my work and I
wanted to contribute it back to the community since several people in
the past have asked me for something along these lines. (Jakob, I know
this has been a while coming ; )]

The way you use this is you create a script that takes in as its first
argument a count. The script passes into LLVM the count via a command
line flag that disables a pass after LLVM has run after the pass has
run for count number of times. Then the script invokes a test of some
sort and indicates whether LLVM successfully compiled the test via the
scripts exit status. Then you invoke bisect as follows:

bisect --start=<start_num> --end=<end_num> ./script.sh "%(count)s"

And bisect will continually call ./script.sh with various counts using
the exit status to determine success and failure.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214610 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Gottesman 2014-08-02 01:39:08 +00:00
parent 2785e77db1
commit bcf8459a40

37
utils/bisect Executable file
View File

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#!/usr/bin/env python
import os
import sys
import argparse
import subprocess
parser = argparse.ArgumentParser()
parser.add_argument('--start', type=int, default=0)
parser.add_argument('--end', type=int, default=(1 << 32))
parser.add_argument('command', nargs='+')
args = parser.parse_args()
start = args.start
end = args.end
print("Bisect 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 Count: %d with (Start, End) = (%d,%d)" % (count, start, end))
cmd = [x % {'count':count} for x in args.command]
print cmd
result = subprocess.call(cmd)
if result == 0:
print(" PASSES! Setting start to count")
start = count
else:
print(" FAILS! Setting end to count")
end = count
print("Last good count: %d" % start)