[clang] [Clang][AMDGPU] Add __builtin_amdgcn_s_buffer_load_<T> (PR #203352)

[Krzysztof Drewniak via cfe-commits]

krzysz00 wrote:

I'd go ahead and make the thing variadic, might as will not block CK on account of the right thing to do not being ready yet

What I'd want is a pile of disclaimers that goes, basically, "do not use this on any memory that might be overwritten during kernel execution as it goes to a separate cache, there is a planned deprecation of this codepath, etc."

(I'm at least trying to push better buffer handling forward slowly now that I'm on the compiler team)

https://github.com/llvm/llvm-project/pull/203352