[Bug target/120256] New: [16 Regression] 4% slowdown of 454.calculix on aarch64

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120256

            Bug ID: 120256
           Summary: [16 Regression] 4% slowdown of 454.calculix 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: 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=574.170.0

there was a 5% exec time slowdown of the 454.calculix SPEC 2006 benchmark
between commits

r16-433-g2c46a74d4707bd
r16-457-g49c44911df72f5

when run with -O2 -march=generic -flto 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=1035.170.0&plot.1=1220.170.0&plot.2=574.170.0&;


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)