[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)

[Shilei Tian via llvm-branch-commits]

shiltian wrote:

This WIP PR stack basically shows how the changes would pan out. It will be easier to review the changes than https://github.com/llvm/llvm-project/pull/166667.

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