[Bug target/80571] AVX allows multiple vcvtsi2ss/sd (integer -> float/double) to reuse a single dep-breaking vxorps, even hoisting it out of loops

[peter at cordes dot ca]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80571

--- Comment #2 from Peter Cordes <peter at cordes dot ca> ---
I think hjl's patch for PR 89071 / PR 87007 fixes (most of?) this, at least for
AVX.

If register pressure is an issue, using a reg holding a arbitrary constant
(instead of xor-zeroed) is a valid option, as this bug points out.  So I'm not
sure we should close this as a duplicate of those fixed bugs.