[Bug target/127773] [x86] vzeroupper missing before call to IPA-RA-known non-AVX callee, causing SSE/AVX transition assists

[michiel.van.slobbe at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127773

--- Comment #11 from Michiel van Slobbe <michiel.van.slobbe at gmail dot com> 
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Created attachment 65823
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=65823&action=edit
Smaller repro detailing edge case in proposed fix