[llvm] [WIP] Consider datalayout sentinel pointer value for isKnownNonZero check (PR #91769)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm commented:

I'm not sure what's going on in the tests. These seem to just be a bunch of existing tests, copied with a datalayout applied 

https://github.com/llvm/llvm-project/pull/91769