[llvm-branch-commits] [llvm] [mlir] [WIP][IR][Constants] Change the semantic of `ConstantPointerNull` to represent an actual `nullptr` instead of a zero-value pointer (PR #183215)

[Matt Arsenault via llvm-branch-commits]

arsenm wrote:

inttoptr 0 seems fine to me. If 0 isn't the null value, 0 isn't special relative to any other integer value 

https://github.com/llvm/llvm-project/pull/183215