On Thu, Dec 6, 2012 at 10:43 PM, Jan Hubicka <hubi...@ucw.cz> wrote: >> The following patch restores the old default limits for loop peeling >> that were recently changed to 100 and caused a 20% degradation in >> 454.calculix. >> >> Bootstrap/regtest on powerpc64-linux with no new regressions. Ok for trunk? >> >> -Pat >> >> >> 2012-12-06 Pat Haugen <pthau...@us.ibm.com> >> * config/rs6000/rs6000.c (rs6000_option_override_internal): Set >> default loop peeling limits. > > Actually the calculix regression is also seen on core. > Igor was looking into what loops got slower and why. Either we can fix that > partiuclar > loop or revert to the old default (that sadly causes quite a lot of code > bloat)
Well, as the patch regressed the testcase in put in the testsuite for calculix that is no surprise... gfortran.dg/reassoc_4.f. The fix for the testcase was to increase the limit with a --param :/ Note that it is even beneficial to unroll two more levels of the nest completely. It's just an insane testcase (and I spent quite some time on it trying to somehow autodetect the simplification opportunities - see the unrolling heuristic rewrite patch I dumped on you a few weeks ago). No advice from me on how to "fix" this ... but eventually the rewrite restores the old behavior with the new limits (I did the rewrite to try to somehow make it do two extra levels of nest unrolling ...). Richard. > Honza
