[Bug target/104122] On Zen3, 510.parest_r (built with -Ofast) is faster with generic than with native ISA

[jamborm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104122

--- Comment #3 from Martin Jambor <jamborm at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #2)
> It's ISA, not tuning.

You are of course correct, unfortunately I am too accustomed to
using the wrong term.

> I suppose -march=native -mtune=generic is still bad?

I don't know, I'd have to manually check.

> I wonder if you tried the obvious -mprefer-avx128?

I hope that is equivalent to -mprefer-vector-width=128

If it is, -march=native -mtune=native -mprefer-vector-width=128 is
even quite a bit slower than -march=native -mtune=native.