[Bug tree-optimization/121218] [15/16 regression] highway miscompiled at -O2 -march=znver2 since r15-3036-gb8ea13ebf12117

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121218

--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 61949
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=61949&action=edit
more reduced and clang-formatted

So this is more reduced (instantiation-wise) and clang formatted and thus
readable.  It has

  //__asm__ volatile ("# FOO" : : : "memory");

in the place where a memory barrier helps.  The bug reproduces with
GCC 15.1.1 and

 -O2 -march=x86-64-v3 -mtune=znver2 -w -fno-tree-loop-vectorize
-fdbg-cnt=vect_slp:1-6:12-18 -fno-tree-tail-merge -fno-strict-aliasing