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

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

Quick question: is this Alive2 proof correct or is there a bug in Alive2? [https://alive2.llvm.org/ce/z/UMaBDK]. If there is no bug in Alive2, there's something wrong with my implementation, which I will work on.

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