>> This patch works around the performance problems that are still in >> current grep. Red Hat will probably be using it in its own 2.6.x. >> >> For UTF-8 it should trigger only in the presence of MBCSET, e.g. [a-z] >> or [à] (nad the latter case could be avoided). >> >> For other character sets all brackets, and `.' as well, will trigger it. > > Sounds like a good change, but please add a comment. > Can you suggest a pathologically bad example > with which we can try to come up with a performance-measuring > addition to the test suite?
If I read correctly the matcher code, it is still an NFA, so it's O(nodes * input-length). So it's difficult to find a pathological case, even though the slowdown is over 200x. Paolo
