https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81616
--- Comment #15 from Jan Hubicka <hubicka at ucw dot cz> --- > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81616 > > --- Comment #14 from Andrew Roberts <andrewm.roberts at sky dot com> --- > It would be nice if znver1 for -march and -mtune could be improved before the > gcc 8 release. At present -march=znver1 -mtune=znver1 looks be to about the > worst thing you could do, and not just on this vectorizable code. And given we > tell people to use -march=native which gives this, it would be nice to > improve. We benchmarked znver1 tuning quite thoroughly with spec2000, spec2006 and 2017 and istuation is not that bad. In August, with -O2 native tuning is about 0.3% (for both in and fp) better than generic (this does not include vectorization becuase of -O2 and keep in mind that spec is often bound by memory, 0.3% difference is quite noticable). All regressions in individual benchmarks were under 2% and some fixed since then. For -Ofast the difference is about 0.5% for integer with two notable regressions wich have WIP solutions for. Integer/core tuning went worse than generic so things was as indtended. I will quickly re-test 256bit vectorization with specfp2k (that is fast). Please attach regressing testcases you have and I will take a look, too. Honza
