[clang] [llvm] [mlir] [AMDGPU] Generalize global.load.lds to buffer fat pointers (PR #134911)

[Krzysztof Drewniak via cfe-commits]

krzysz00 wrote:

`void raw.buffer.ptr.load.lds(p8 rsrc, p3 lds, i32 immarg size, i32 voffset, i32 soffset, i32 immarg immOff, i32 immarg aux)`

However

`void raw.buffer.fat.ptr.load.lds(p7 fatPtr, p3 lds, i32 immarg size, i32 immarg immoff, i32 immarg aux)`

Please note that the buffer.ptr version takes a voffset argument which is a *part of the buffer fat pointer*

You have to *lower* the fat pointer LDS load to *extract* the voffset argument

https://github.com/llvm/llvm-project/pull/134911