[llvm] [DA] getBackedgeTakenCount in isKnownLessThan can return CouldNotCompute (PR #162495)

[Ryotaro Kasuga via llvm-commits]

https://github.com/kasuga-fj commented:

Could you please clarify the motivation for this change? When I tried the test case you added, it crashed. So I guess this PR is meant to address that issue, right?

Side note: Although fixing such a bug is fine to me, I believe this function has multiple correctness issues and should be removed in the first place.

https://github.com/llvm/llvm-project/pull/162495