[clang] [llvm] [AMDGPU] Add initial support for VGPR as memory (PR #205435)

[Gheorghe-Teodor Bercea via cfe-commits]

doru1004 wrote:

> You should also add global isel support.
> 

Planned as a follow-up PR.

> It would also be easier to review if you split it into a couple patches (one for the clang bits, one for promote alloca, one for instruction selection etc).

Will split once the overall design is agreed. I just want to have an end to end picture available for discussion.

https://github.com/llvm/llvm-project/pull/205435