[clang] [Clang][AMDGPU] Add builtins for instrinsic `llvm.amdgcn.raw.buffer.store` (PR #94576)

[Matt Arsenault via cfe-commits]

arsenm wrote:

> 1. For the swizzled case, that's `struct.ptr.buffer.*`, and yeah, those will always need builtins because LLVM can't deal in 2D addressing schemes

But the raw buffer intrinsics have both the soffset and voffset parameters though? Not just the struct 



https://github.com/llvm/llvm-project/pull/94576