[Bug target/121991] New: [16 Regression] 15% slowdown of 436.cactusADM and 7% slowdown of 410.bwaves on Aarch64

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121991

            Bug ID: 121991
           Summary: [16 Regression] 15% slowdown of 436.cactusADM and 7%
                    slowdown of 410.bwaves 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=574.100.0
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=574.40.0

there was a 15% slowdown of 436.cactusADM and 7% slowdown of 410.bwaves SPEC
2006 benchmarks between commits

r16-3274-gf0c761165929cd
r16-3288-g273a4d3775df00

when compiled with -O2 -flto (generic march) on an Ampere Altra (Neoverse N1)
machine.


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)