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 import os
  16 import sys
  17 import argparse
  18 import subprocess
  19
  20 parser = argparse.ArgumentParser()
  21
  22 parser.add_argument('--start', type=int, default=0)
  23 parser.add_argument('--end', type=int, default=(1 << 32))
  24 parser.add_argument('command', nargs='+')
  25
  26 args = parser.parse_args()
  27
  28 start = args.start
  29 end = args.end
  30
  31 print("Bisect Starting!")
  32 print("Start: %d" % start)
  33 print("End: %d" % end)
  34
  35 last = None
  36 while start != end and start != end-1:
  37     count = start + (end - start)/2
  38     print("Visiting Count: %d with (Start, End) = (%d,%d)" % (count, start, end))
  39     cmd = [x % {'count':count} for x in args.command]
  40     print cmd
  41     result = subprocess.call(cmd)
  42     if result == 0:
  43         print("    PASSES! Setting start to count")
  44         start = count
  45     else:
  46         print("    FAILS! Setting end to count")
  47         end = count
  48
  49 print("Last good count: %d" % start)