[Bug tree-optimization/124408] New: [16 Regression] 4% slowdown of exchange2_r on Intel Ice Lake

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124408

            Bug ID: 124408
           Summary: [16 Regression] 4% slowdown of exchange2_r on Intel
                    Ice Lake
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: missed-optimization, needs-bisection
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jmelcr at gcc dot gnu.org
            Blocks: 26163
  Target Milestone: ---
              Host: x86_64-suse-linux
            Target: x86_64-suse-linux

As seen here

https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=786.407.0

there was a 4% exec time slowdown of the exchange2_r SPEC 2017 benchmark
between commits

r16-7824-g8758503918a91d
r16-7932-gbef3d986109c65

when compiled with -O2 -g on an Intel Ice Lake (3rd generation Xeon) machine.

This is a regression against GCC 14, but not against GCC 15. See the comparison
here:

https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=812.407.0&plot.1=849.407.0&plot.2=823.407.0&plot.3=909.407.0&plot.4=1092.407.0&plot.5=1208.407.0&plot.6=786.407.0&;


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)