[Bug target/119412] New: 7% slowdown of 482.sphinx3 on Aarch64

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119412

            Bug ID: 119412
           Summary: 7% slowdown of 482.sphinx3 on Aarch64
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: missed-optimization, 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: aarch64-gnu-linux
            Target: aarch64-gnu-linux

As seen here

https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=580.280.0
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=579.280.0

there was a 7% exec time slowdown of the 482.sphinx3 SPEC 2006 benchmark
between commits

r15-7897-ge6e7b477bbdbfb
r15-8041-g57dbbdd8e34b80

when run with -O2 -march=native, with and without -flto on an Ampere Altra
Neoverse N1 machine.

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

https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.8=1042.280.0&plot.9=580.280.0&;
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.8=1052.280.0&plot.9=579.280.0&;


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)