[milestone] Compile all DML shaders, and they pass the validator

[damyanp]

This is a milestone on the way to getting full HLSL support in Clang.

For this milestone we need to have enough features working in Clang that we can compile all of DML's shaders - and that the compiled shaders pass the validator. Extra bonus points if we run them as well!

The work items listed here are expected to be fully completed - even if that means doing more than the bare minimum required to pass this milestone.

Workstreams

Language (#21)

• Identify remaining language features for DirectML
• [HLSL] vector subscript indexing llvm-project#91640
• [HLSL] Copy in/copy out parameter passing llvm-project#87526 (out and inout keywords)
• HLSL initializer list support llvm-project#56067

Resource Binding (#23)

• Implicit resource binding

Semantics (#25)

• Support all compute semantics and lowering to DXIL ops
• Generalized Semantic and Signature Point implementation plan
• Capture Signature Element mapping on entry parameters in AST
• Type checking for semantics

Intrinsics (#28)

• Intrinsics used by DML shaders are implemented #30

Resources (#8)

• Raw Buffers #10

DirectX Container (#9)

• Add Root Signature part
• Generated container can be signed through DXV
• Generate full PSV0 part for compute shaders llvm-project#96674
• DXIL Shader Flags #57