[RFC] Adding HLSL and DirectX support to Clang & LLVM

[Flakebi]

@beanz

DXIL is LLVM 3.7 IR as bitcode with a wide set of constraints on how the IR is structured. One of the key features of DXIL is that it is readable by backends that are LLVM and backends that are not.

Nothing in DXIL can’t be represented in LLVM IR, but some things in DXIL are represented in unusual ways to make DXIL easier to parse by non-LLVM compilers.

I wonder if you have any plans on how DXIL can be read with opaque pointers? (there was a bit of discussion in this post)
I think, e.g. the type of a raytracing payload struct would be unknown when using opaque pointers (if it is unused and only appears as a pointer argument).