[llvm] KnownBits: refine srem for high-bits (PR #109121)

[Jay Foad via llvm-commits]

https://github.com/jayfoad commented:

I think the patch is OK as written but it is strange that you only handle the cases where LHS and RHS are both positive or both negative. What about a case like `LHS % 3` where LHS is known to be negative? The inline suggestions try to handle those cases too - but would need extra test coverage.

https://github.com/llvm/llvm-project/pull/109121