This issue handles the additional semantic analysis of the parsed HLSLRootSignature attribute. This includes generating applicable diagnostics.

The relevant validations that this issue must implement are:

• Ensure valid flag combinations of DESCRIPTOR_RANGE_FLAGS and ROOT_DESCRIPTOR_FLAGS
• Ensure valid values of DESCRIPTOR_RANGE_FLAGS for the Sampler descriptor table clause
• Ensure that listed parameters of StaticSampler are bounded correctly
• Validate that the space parameter is not in the invalid range of 0xFFFFFFF0 to 0xFFFFFFFF
• Validate that the numDescriptors parameter is not 0.
• Ensure that the correct register type matches the desriptor range type - this is handled during parsing

AC:

• Update ParseHLSLRootSignature defined in [HLSL] Generate AST for Root Signatures #119011 to implement semantic validation of HLSLRootSignature
• Update handleHLSLRootSignature to implement semantic validation of HLSLRootSignature in SemaHLSL.cpp
• Add thorough testing of correct diagnostics into clang/unittests/Sema/ParseHLSLRootSignatureTest.cpp
• Add tests for some samples to ensure diagnostics are displayed correctly from HLSL input in AST/HLSL/RootSignatures-AST.hlsl