[Bug target/116078] New: [15 Regression] 10-12% slowdown of 436.cactusADM on AMD Zen2

[pheeck at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116078

            Bug ID: 116078
           Summary: [15 Regression] 10-12% slowdown of 436.cactusADM on
                    AMD Zen2
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: needs-bisection
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pheeck at gcc dot gnu.org
            Blocks: 26163
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu

As seen here

https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=292.100.0

there was a 12% (only 10% on another machine I measured) exec time slowdown of
the 436.cactusADM SPEC 2006 benchmark between commits

r15-2152-gcea6473e48b4cf
r15-2190-g913bab282d95e8

when run with -O2 -march=generic -flto on an AMD Zen 2 machine.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26163
[Bug 26163] [meta-bug] missed optimization in SPEC (2k17, 2k and 2k6 and 95)