[llvm] [DirectX] Documenting Root Signature Binary representation (PR #131011)

[Justin Bogner via llvm-commits]

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@@ -400,3 +400,273 @@ SFI0 Part
 The SFI0 part encodes a 64-bit unsigned integer bitmask of the feature flags.
 This denotes which optional features the shader requires. The flag values are
 defined in `llvm/include/llvm/BinaryFormat/DXContainerConstants.def <https://github.com/llvm/llvm-project/blob/main/llvm/include/llvm/BinaryFormat/DXContainerConstants.def>`_.
+
+Root Signature (RTS0) Part
+--------------------------
+.. _RTS0:
+
+The Root Signature defines the interface between the shader and the pipeline, 
+specifying which resources are bound to the shader and how they are accessed. 
+This structure serves as a contract between the application and the GPU, 
+establishing a layout for resource binding that both the shader compiler and 
+the runtime can understand.
----------------
bogner wrote:

These two sentences feel very redundant with one another, and neither really has a lot of content. The first says this defines an interface and the second literally defines what an interface is. Something like "The root signature part describes how resources are bound to the shader pipeline" is both more direct and clearer.

https://github.com/llvm/llvm-project/pull/131011