[llvm] [SCEV] Check bitwidth for constant ranges comparison (PR #150364)

[via llvm-commits]

annamthomas wrote:

I think this should at least be an assert? 

I used the `isKnownPredicate` downstream without converting the SCEV to the wider type and faced the crash when going through this API. 


https://github.com/llvm/llvm-project/pull/150364