[llvm] [SCEV] Fold (C1 * A /u C2) -> A /u (C2 /u C1), if C2 > C1. (PR #157656)

[Devon Loehr via llvm-commits]

DKLoehr wrote:

We've started seeing crashes in the rust compiler when using head LLVM, and it bisected to this commit. Unfortunately I'm not sure how to put together a useful reproducer. It's possible there's a bug here or that it simply revealed one elsewhere. 

https://github.com/llvm/llvm-project/pull/157656