[llvm] [NewPM] Port x86-issue-vzero-upper (PR #180886)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon requested changes to this pull request.

(pet peeve) Please can we rename this X86InsertVZeroUpper? I've never understood why it was called Issue and this seems the perfect opportunity :/ 

https://github.com/llvm/llvm-project/pull/180886