[Bug tree-optimization/116761] New: [15 Regression] 4-6% slowdown of 465.tonto on AMD Zen3/4

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116761

            Bug ID: 116761
           Summary: [15 Regression] 4-6% slowdown of 465.tonto on AMD
                    Zen3/4
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: missed-optimization, needs-bisection
          Severity: normal
          Priority: P3
         Component: tree-optimization
          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=476.230.0
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=992.230.0

there was a 4-6% exec time slowdown of the 465.tonto SPEC 2006 benchmark
between commits

r15-3503-ga2e28b105cea4c
r15-3534-gbfb9105ffbff95

when run with -Ofast -march=native -flto on AMD Zen3/4 machines.


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)