[Bug tree-optimization/121256] [13/14/15/16 regression] ffmpeg miscompiled with -O2 -march=znver2

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121256

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot 
gnu.org
   Last reconfirmed|                            |2025-07-27
     Ever confirmed|0                           |1
             Target|                            |x86_64-*-*
           Keywords|                            |needs-bisection
             Status|UNCONFIRMED                 |ASSIGNED

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.  Fails with -O -ftree-loop-vectorize -march=znver2

Probably caused by the first order recurrence vectorization addition.  I think
we get the dependence wrong.