[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)

[Demetrius Kanios via llvm-branch-commits]

QuantumSegfault wrote:

I wonder, would this (perhaps with additional work?) eventually allow Wasm's `ref.null` for `externref` and `funcref` to be lowered from this new `nullptr`, rather than requiring an intrinsic call. 

Wasm uses non-integral address spaces to represent `externref` and `funcref`. But this PR just seems to impact the integer null value of integral pointers?

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