[Bug target/121440] New: [16 Regression] 50% slowdown of 519.lbm_r on Zen5 since r16-2727-g09f0768b55b96c (the fix for pr120941)

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121440

            Bug ID: 121440
           Summary: [16 Regression] 50% slowdown of 519.lbm_r on Zen5
                    since r16-2727-g09f0768b55b96c (the fix for pr120941)
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pheeck at gcc dot gnu.org
                CC: hjl.tools at gmail dot com, rguenth at gcc dot gnu.org
            Blocks: 26163
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu,
            Target: x86_64-pc-linux-gnu

So the fix for pr120941 apparently slows down 519.lbm_r with -Ofast
-march=native -flto on our Zen5 machine by ~50% :(.

https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=1288.477.0

H.J., Richi, any ideas (intuition) about what this could be?  I'll try to find
out what is going on and produce a testcase.


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)