[Bug target/120218] New: [16 Regression] 8% slowdown of 507.cactuBSSN_r on Intel

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120218

            Bug ID: 120218
           Summary: [16 Regression] 8% slowdown of 507.cactuBSSN_r on
                    Intel
           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: 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=793.437.0

there was an 8% exec time slowdown of the 507.cactuBSSN_r SPEC 2017 benchmark
between commits

r16-117-g2056d52d74070f
r16-310-g3584aab37f54bc

when run with -Ofast -march=generic on an Intel Ice Lake (3rd generation Xeon)
machine.

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

https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=1095.437.0&plot.1=1210.437.0&plot.2=793.437.0&;


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)