Design target("dx.CBuffer", ...) type

[bogner]

We need a documented design on how the target extension types for CBuffers work and their load operations work in LLVM. These need to at minimum store the size of the contents, but ideally have richer information about the contents and layout so that we can abstract these details throughout the middle end.

A.C.

• The proposed design is documented in DXIL Resources.rst
• A document documenting the reasoning is created in the wg-hlsl repo