[llvm] [WIP] Extend data layout to add sentinel pointer value for address space. (PR #83109)

[Rana Pratap Reddy via llvm-commits]

ranapratap55 wrote:

> This needs additional context work to be reasonably evaluated. At a minimum, we need to refactor ValueTracking's isKnownNonZero to a separate variant that specifically understands pointer validity

Created PR #91769.

https://github.com/llvm/llvm-project/pull/83109