[llvm] [CVP]: Fold `icmp eq X, C` to `trunc X to i1` if C=2k+1 and X in [2k, 2k+1] (PR #83829)

[Orson Peters via llvm-commits]

orlp wrote:

@YanWQ-monad Looking at your [godbolt](https://godbolt.org/z/xMTbP94Yn), doesn't that still have the useless `and` with 1 on ARM? 

https://github.com/llvm/llvm-project/pull/83829