[Bug other/96825] New: Commit r11-2645 degrades CPU2017 548.exchange2_r by 35%

[pthaugen at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96825

            Bug ID: 96825
           Summary: Commit r11-2645 degrades CPU2017 548.exchange2_r by
                    35%
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pthaugen at gcc dot gnu.org
                CC: bergner at gcc dot gnu.org, hubicka at gcc dot gnu.org,
                    segher at gcc dot gnu.org, seurer at gcc dot gnu.org,
                    wschmidt at gcc dot gnu.org
  Target Milestone: ---
              Host: powerpc64-unknown-linux-gnu
            Target: powerpc64-unknown-linux-gnu
             Build: powerpc64-unknown-linux-gnu

The given commit (1118a3ff9d3ad6a64bba25dc01e7703325e23d92) causes a 35%
degradation for exchange2_r on Power9 built with the options "-O2
-mcpu=power9". Switching to -O3 results in a 44% degradation. The degradation
occurs in __brute_force_MOD_digits_2().