[DirectX] Moving Root Signature Metadata Parsing in to Shared Root Signature Metadata lib (#149221)

This PR, moves the existing Root Signature Metadata Parsing logic used
in `DXILRootSignature` to the common library used by both frontend and
backend. Closes:
[#145942](#145942)

---------

Co-authored-by: joaosaffran <[email protected]>

Author: joaosaffran

llvm/include/llvm/Frontend/HLSL/RootSignatureMetadata.h

@@ -15,6 +15,8 @@
 #define LLVM_FRONTEND_HLSL_ROOTSIGNATUREMETADATA_H
 
 #include "llvm/Frontend/HLSL/HLSLRootSignature.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/MC/DXContainerRootSignature.h"
 
 namespace llvm {
 class LLVMContext;
@@ -49,6 +51,48 @@ class MetadataBuilder {
   SmallVector<Metadata *> GeneratedMetadata;
 };
 
+enum class RootSignatureElementKind {
+  Error = 0,
+  RootFlags = 1,
+  RootConstants = 2,
+  SRV = 3,
+  UAV = 4,
+  CBV = 5,
+  DescriptorTable = 6,
+  StaticSamplers = 7
+};
+
+class MetadataParser {
+public:
+  MetadataParser(MDNode *Root) : Root(Root) {}
+
+  LLVM_ABI bool ParseRootSignature(LLVMContext *Ctx,
+                                   mcdxbc::RootSignatureDesc &RSD);
+
+private:
+  bool parseRootFlags(LLVMContext *Ctx, mcdxbc::RootSignatureDesc &RSD,
+                      MDNode *RootFlagNode);
+  bool parseRootConstants(LLVMContext *Ctx, mcdxbc::RootSignatureDesc &RSD,
+                          MDNode *RootConstantNode);
+  bool parseRootDescriptors(LLVMContext *Ctx, mcdxbc::RootSignatureDesc &RSD,
+                            MDNode *RootDescriptorNode,
+                            RootSignatureElementKind ElementKind);
+  bool parseDescriptorRange(LLVMContext *Ctx, mcdxbc::DescriptorTable &Table,
+                            MDNode *RangeDescriptorNode);
+  bool parseDescriptorTable(LLVMContext *Ctx, mcdxbc::RootSignatureDesc &RSD,
+                            MDNode *DescriptorTableNode);
+  bool parseRootSignatureElement(LLVMContext *Ctx,
+                                 mcdxbc::RootSignatureDesc &RSD,
+                                 MDNode *Element);
+  bool parseStaticSampler(LLVMContext *Ctx, mcdxbc::RootSignatureDesc &RSD,
+                          MDNode *StaticSamplerNode);
+
+  bool validateRootSignature(LLVMContext *Ctx,
+                             const llvm::mcdxbc::RootSignatureDesc &RSD);
+
+  MDNode *Root;
+};
+
 } // namespace rootsig
 } // namespace hlsl
 } // namespace llvm

llvm/include/llvm/MC/DXContainerRootSignature.h

@@ -6,6 +6,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+#ifndef LLVM_MC_DXCONTAINERROOTSIGNATURE_H
+#define LLVM_MC_DXCONTAINERROOTSIGNATURE_H
+
 #include "llvm/BinaryFormat/DXContainer.h"
 #include <cstdint>
 #include <limits>
@@ -116,3 +119,5 @@ struct RootSignatureDesc {
 };
 } // namespace mcdxbc
 } // namespace llvm
+
+#endif // LLVM_MC_DXCONTAINERROOTSIGNATURE_H