Hello, On Thu, 14 Oct 2021, Richard Biener via Gcc-patches wrote:
> > I have bisected an AMD zen2 10% performance regression of SPEC 2006 FP > > 433.milc bechmark when compiled with -Ofast -march=native -flto to this > > commit. See also: > > > > > > https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=412.70.0&plot.1=289.70.0& > > > > I am not sure if a bugzilla bug is in order because I cannot reproduce > > the regression neither on an AMD zen3 machine nor on Intel CascadeLake, > > It's for sure worth a PR for tracking purposes. But I've not been > very successful in identifying regression causes on Zen2 - what perf > points to is usually exactly the same assembly in both base and peak :/ Well, in this case it's at least a fairly impressive (40%) difference in samples for add_force_to_mom* : > > BEFORE: > > 18.47% 105497 milc_peak.mine- milc_peak.mine-lto-nat [.] > > add_force_to_mom > > > > AFTER: > > 24.04% 149010 milc_peak.mine- milc_peak.mine-lto-nat [.] > > add_force_to_mom (as the change was in the vectorizer this shouldn't be different inlining decisions hopefully). Ciao, Michael.