utils/bisect

   1 #!/usr/bin/env python
   2 #
   3 # The way you use this is you create a script that takes in as its first
   4 # argument a count. The script passes into LLVM the count via a command
   5 # line flag that disables a pass after LLVM has run after the pass has
   6 # run for count number of times. Then the script invokes a test of some
   7 # sort and indicates whether LLVM successfully compiled the test via the
   8 # scripts exit status. Then you invoke bisect as follows:
   9 #
  10 # bisect --start=<start_num> --end=<end_num> ./script.sh "%(count)s"
  11 #
  12 # And bisect will continually call ./script.sh with various counts using
  13 # the exit status to determine success and failure.
  14 #
  15 from __future__ import print_function
  16 import os
  17 import sys
  18 import argparse
  19 import subprocess
  20
  21 parser = argparse.ArgumentParser()
  22
  23 parser.add_argument('--start', type=int, default=0)
  24 parser.add_argument('--end', type=int, default=(1 << 32))
  25 parser.add_argument('command', nargs='+')
  26
  27 args = parser.parse_args()
  28
  29 start = args.start
  30 end = args.end
  31
  32 print("Bisect Starting!")
  33 print("Start: %d" % start)
  34 print("End: %d" % end)
  35
  36 last = None
  37 while start != end and start != end-1:
  38     count = start + (end - start)//2
  39     print("Visiting Count: %d with (Start, End) = (%d,%d)" % (count, start, end))
  40     cmd = [x % {'count':count} for x in args.command]
  41     print(cmd)
  42     result = subprocess.call(cmd)
  43     if result == 0:
  44         print("    PASSES! Setting start to count")
  45         start = count
  46     else:
  47         print("    FAILS! Setting end to count")
  48         end = count
  49
  50 print("Last good count: %d" % start)