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#!/usr/bin/env python3
"""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.
"""
from __future__ import print_function
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 = range(0, args.rungs, 2)
rung2 = range(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()
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