[Bug target/123942] New: [16 Regression] 4% slowdown of povray_r on Aarch64

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123942

            Bug ID: 123942
           Summary: [16 Regression] 4% slowdown of povray_r on Aarch64
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: missed-optimization, needs-bisection
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jmelcr at gcc dot gnu.org
                CC: 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=581.467.0

there was a 4% exec time slowdown of the povray_r SPEC 2017 benchmark between
commits

r16-7132-gef8af34e0d1737
r16-7163-g4df77a254263e9

when compiled with -O2 -g -flto=128 on an Ampere Altra Neoverse N1 machine.

This is a regression against GCC 15. See the comparison
here:

https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=631.467.0&plot.1=679.467.0&plot.2=661.467.0&plot.3=651.467.0&plot.4=614.467.0&plot.5=598.467.0&plot.6=776.467.0&plot.7=875.467.0&plot.8=1045.467.0&plot.9=1235.467.0&plot.10=581.467.0&;


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)