llvm-project

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#!/usr/bin/env python
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#
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# The way you use this is you create a script that takes in as its first
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# argument a count. The script passes into LLVM the count via a command
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# line flag that disables a pass after LLVM has run after the pass has
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# run for count number of times. Then the script invokes a test of some
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# sort and indicates whether LLVM successfully compiled the test via the
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# scripts exit status. Then you invoke bisect as follows:
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#
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# bisect --start=<start_num> --end=<end_num> ./script.sh "%(count)s"
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#
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# And bisect will continually call ./script.sh with various counts using
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# the exit status to determine success and failure.
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#
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from __future__ import print_function
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import os
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import sys
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import argparse
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import subprocess
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parser = argparse.ArgumentParser()
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parser.add_argument('--start', type=int, default=0)
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parser.add_argument('--end', type=int, default=(1 << 32))
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parser.add_argument('command', nargs='+')
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args = parser.parse_args()
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start = args.start
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end = args.end
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print("Bisect Starting!")
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print("Start: %d" % start)
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print("End: %d" % end)
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last = None
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while start != end and start != end-1:
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    count = start + (end - start)//2
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    print("Visiting Count: %d with (Start, End) = (%d,%d)" % (count, start, end))
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    cmd = [x % {'count':count} for x in args.command]
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    print(cmd)
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    result = subprocess.call(cmd)
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    if result == 0:
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        print("    PASSES! Setting start to count")
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        start = count
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    else:
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        print("    FAILS! Setting end to count")
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        end = count
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print("Last good count: %d" % start)
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