[Bug target/119410] New: 5% slowdown of 510.parest_r on Intel Ice Lake

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119410

            Bug ID: 119410
           Summary: 5% slowdown of 510.parest_r on Intel Ice Lake
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          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-linux
            Target: x86_64-linux

As seen here

https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=796.457.0
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=801.457.0

there was a 5% exec time slowdown of the 510.parest_t SPEC 2017 benchmark
between commits

r15-7978-g7efe3aa9b5d4d7
r15-8017-g4e6967aba1aaa9

when run with -Ofast -march=native, with and withou -flto on an Intel Ice Lake
(3rd generation Xeon) machine.

This is *not* a regression against GCC 14. See the comparison
here:

https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.4=1093.457.0&plot.5=801.457.0&;
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.4=1097.457.0&plot.5=796.457.0&;


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)