text: #!/usr/bin/env python
  """A ladder graph creation program.
  
  This is a python program that creates c source code that will generate
  CFGs that are ladder graphs.  Ladder graphs are generally the worst case
  for a lot of dominance related algorithms (Dominance frontiers, etc),
  and often generate N^2 or worse behavior.
  
  One good use of this program is to test whether your linear time algorithm is
  really behaving linearly.
  """
  
  import argparse
  def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('rungs', type=int,
                        help="Number of ladder rungs. Must be a multiple of 2")
    args = parser.parse_args()
    if (args.rungs % 2) != 0:
      print "Rungs must be a multiple of 2"
      return
    print "int ladder(int *foo, int *bar, int x) {"
    rung1 = xrange(0, args.rungs, 2)
    rung2 = xrange(1, args.rungs, 2)
    for i in rung1:
      print "rung1%d:" % i
      print "*foo = x++;"
      if i != rung1[-1]:
        print "if (*bar) goto rung1%d;" % (i+2)
        print "else goto rung2%d;" % (i+1)
      else:
        print "goto rung2%d;" % (i+1)
    for i in rung2:
      print "rung2%d:" % i
      print "*foo = x++;"
      if i != rung2[-1]:
        print "goto rung2%d;" % (i+2)
      else:
        print "return *foo;"
    print "}"
  
  if __name__ == '__main__':
    main()
  