https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113847
Bug ID: 113847 Summary: [14 Regression] 10% slowdown of 462.libquantum on AMD Ryzen 7700X and Ryzen 7900X Product: gcc Version: 14.0 Status: UNCONFIRMED Keywords: missed-optimization, needs-bisection Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: fkastl at suse dot cz Target Milestone: --- Host: x86_64-linux Target: x86_64-linux As seen here https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=956.210.0 between commits g:d826596acb02edf4 and g:23cd2961bd2ff635 there is about 10% slowdown of execution time of the 2006SPEC 462.libquantum benchmark. The test is run with -O2 and lto on an AMD Ryzen 7700X. I also reproduced the slowdown on a AMD Ryzen 7900X machine. However I wasn't able to reproduce the slowdown on an AMD EPYC machine - also Zen4 microarchitecture. So I suppose this slowdown occurs only on Zen4 Ryzen CPUs or is maybe even more specific. I'm not sure if we want to do anything about this. The same slowdown on the same machine has already happened once, see pr112547. The benchmark results eventually returned to the original values.