[llvm] [SCEV] Collect and merge loop guards through PHI nodes with multiple incoming values (PR #113915)

[Florian Hahn via llvm-commits]

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

LGTM, thanks given the latest compile-time numbers.

Would be good to wait to see if @nikic has any further comments (or concerns re compile-time)

https://github.com/llvm/llvm-project/pull/113915