[llvm] [LV] Extend FindLastIV to unsigned case (PR #141752)

[Florian Hahn via llvm-commits]

https://github.com/fhahn approved this pull request.

LGTM, thanks!

> > The other alternative is a strange asymmetry in calls to addReductionVar.
> 
> After thinking some more, I think this is the best compromise: I've updated the patch.

Yep that matches the approach in https://github.com/llvm/llvm-project/pull/140451 I think.

https://github.com/llvm/llvm-project/pull/141752