[clang] [lld] [llvm] [mlir] [IR] Introduce `T<address space>` to `DataLayout` to represent flat address space if a target supports it (PR #108786)

[Shilei Tian via cfe-commits]

shiltian wrote:

> Why is that a DL property and not just a target property?

It is indeed a target property. DL is one choice here (if it is not the most preferable one). Like I mentioned before, TTI and `TargetMachine` could have been one, but not feasible. Where else do you suggest?

> Or even just "computable" by asking query 1) for different ASs?

IIUC, the query 1) you were referring to was `Type::canLosslesslyBitCastTo`. If that's the case, it does nothing for AS cast.

https://github.com/llvm/llvm-project/pull/108786