[llvm] [CodeGenPrepare] Folding `urem` with loop invariant value as remainder (PR #96625)

[via llvm-commits]

goldsteinn wrote:

Im pretty sure I see the bug.

The issue is that while `Rem` might be a loop-invariant in its loop, it might not be a loop invariant in the PHI loop. The fix is what nikic recommended, to just get the loop from the PHI instead of the Rem.

https://github.com/llvm/llvm-project/pull/96625