[workstream] Root Signatures

[damyanp]

HLSL uses Root Signatures to specify the table of resources and other binding elements. In DirectX 12+ root signatures can be specified in HLSL source files using the [RootSignature(...)] attribute on entry functions and a signature description syntax defined in this documentation:

https://learn.microsoft.com/en-us/windows/win32/direct3d12/specifying-root-signatures-in-hlsl

Root Signatures are compiled into attributes embedded in the IR that then get encoded into runtime data structures which are read by the D3D runtime.

Milestones

Compile a broad selection of compute shaders (#11)

• [HLSL] Root Signature support (non-library) llvm-project#119032
• [HLSL] Add support for "rootsig" targets llvm-project#99523

Ray Tracing (#18)

• Local Root Signatures