Yury Selivanov added the comment: Attaching an updated patch.
> 1. I think you're missing the final multiplication by Py_SIZE(b) in the > fast_mod code. Which is odd, because your tests should catch that. So either > you didn't run the tests, or that code path isn't being used somehow. Thanks. Not sure how this happened :( > 2. Talking of tests, it would be good to have tests (for both // and %) for > the case where the dividend is an exact multiple of the divisor. Done. > 3. Negative divisors almost never come up in real life, so you might also > consider restricting the optimisations to the case Py_SIZE(b) == 1 (rather > than ABS(Py_SIZE(b)) == 1). If that makes any speed difference at all for the > case of positive divisors, then it's probably worth it. If not, then don't > worry about it. Tried it, the difference is very small. For modulo division it's ~0.225 usec vs ~0.23 usec for [-m timeit -s "x=22331" "x%2;x%3;x%4;x%5;x%6;x%7;x%8;x%99;x%100;"] ---------- Added file: http://bugs.python.org/file41886/fast_divmod_5.patch _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue26289> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
