https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102861
--- Comment #6 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
> > Is there something else we could do?
>
> Look what exactly is missing and restore that - testcases are written
> from real-world code that we expect to optimize, adjusting them to
> hide the fact that we don't any longer is not good.
>
> Even XFAIL would have been better.
Heh. That was my original suggestion, but I was vetoed :).
>
> That said, loop header copying is supposed to do the rotation.
>
> Note what I see on the unchanged testcase is that we now loop vectorize
> which is great (and obviously no BB vectorization opportunity remains).
> So a different fix would be to simply add
>
> /* Avoid loop vectorization. */
> /* { dg-additional-options "-fno-tree-loop-vectorize" } */
>
> which makes the testcase PASS again (bonus for adding a variant
> of the testcase that verifies we loop vectorize this).
>
> Let me do all this for you.
Thanks so much!
