[llvm] [SPIRV] Expand RWBuffer load and store from HLSL (PR #122355)

[Nathan Gauër via llvm-commits]

https://github.com/Keenuts commented:

LGTM overall.
I wonder how optimizations will do with this IR (is the getpointer considered to have a side-effect to prevent moving it? and other transforms like reg2mem), but we might want to start with this, and then see how it breaks.

https://github.com/llvm/llvm-project/pull/122355