[llvm] [SimplifyCFG] Convert switch to cmp/select sequence (PR #82795)

[Acim Maravic via llvm-commits]

Acim-Maravic wrote:

Fixed support for handling of multiple PHI nodes. Reworked implementation to try to carve out cases with constant values instead of giving up if not all cases are constant.

https://github.com/llvm/llvm-project/pull/82795