[llvm] [SCEV] Rewrite more SCEVAddExpr when applying guards. (PR #159942)

[Florian Hahn via llvm-commits]

================

----------------
fhahn wrote:

The changes here actually was a regression, as we failed to determine the expected multple of the trip count from the guards. To fix that, I think we need to improve the divisibility handling in general: https://github.com/llvm/llvm-project/pull/163021 (included in this PR now)

https://github.com/llvm/llvm-project/pull/159942