[clang] [llvm] [HLSL][RootSignature] Add metadata generation for descriptor tables (PR #139633)

[Justin Bogner via cfe-commits]

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@@ -160,6 +163,65 @@ void dumpRootElements(raw_ostream &OS, ArrayRef<RootElement> Elements) {
   OS << "}";
 }
 
+MDNode *MetadataBuilder::BuildRootSignature() {
+  for (const RootElement &Element : Elements) {
+    MDNode *ElementMD = nullptr;
+    if (const auto &Clause = std::get_if<DescriptorTableClause>(&Element))
+      ElementMD = BuildDescriptorTableClause(*Clause);
+    if (const auto &Table = std::get_if<DescriptorTable>(&Element))
+      ElementMD = BuildDescriptorTable(*Table);
+
+    // FIXME(#126586): remove once all RootElemnt variants are handled in a
+    // visit or otherwise
+    assert(ElementMD != nullptr &&
+           "Constructed an unhandled root element type.");
+
+    GeneratedMetadata.push_back(ElementMD);
+  }
+
+  return MDNode::get(Ctx, GeneratedMetadata);
+}
+
+MDNode *MetadataBuilder::BuildDescriptorTable(const DescriptorTable &Table) {
+  IRBuilder<> B(Ctx);
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bogner wrote:

`B` is not a good name for an `IRBuilder` (despite that it does seem to be used a fair amount). `IRB` and `Builder` are both more common names for these, and I definitely lean towards the latter.

https://github.com/llvm/llvm-project/pull/139633