[clang] [flang] [llvm] [NFC][AMDGPU] Move address space enum to LLVM directory (PR #73944)

[Krzysztof Parzyszek via cfe-commits]

kparzysz wrote:

> I'd just move these definitions to their own file, and use that file in clang/flang/llvm backend. So, indirectly, yes.

Sorry, didn't notice you have already created a separate file: 👍 I'd just use the address space identifiers that you quoted instead.

https://github.com/llvm/llvm-project/pull/73944