[llvm] [LLVM][SCEV] Look through common multiplicand when simplifying compares. (PR #141798)

[Paul Walker via llvm-commits]

paulwalker-arm wrote:

> This should have some dedicated tests in test/Analysis/ScalarEvolution.

I struggled to write scalar-evolution specific tests because the output does not seem to show `icmp` expressions and the change is not related to calculating backed taken counts which many of the tests focus on.  Have you advice for how best to test the `isKnownPredicate` routines in isolation?

https://github.com/llvm/llvm-project/pull/141798