add support for associating DescriptorTables with their clauses

Author: inbelic

clang/test/CodeGenHLSL/RootSignature.hlsl

@@ -6,12 +6,14 @@
 void FirstEntry() {}
 
 // CHECK-DAG: ![[#CBV:]] = !{!"CBV", i32 1, i32 0, i32 0, i32 -1, i32 4}
-// CHECK-DAG: ![[#TABLE:]] = !{!"DescriptorTable"}
+// CHECK-DAG: ![[#SRV:]] = !{!"SRV", i32 4, i32 42, i32 3, i32 32, i32 0}
+// CHECK-DAG: ![[#TABLE:]] = !{!"DescriptorTable", i32 0, ![[#CBV]], ![[#SRV]]}
 // CHECK-DAG: ![[#SECOND_RS:]] = !{![[#TABLE]]}
 
 #define SampleDescriptorTable \
   "DescriptorTable( " \
-  "  CBV(b0) " \
+  "  CBV(b0), " \
+  "  SRV(t42, space = 3, offset = 32, numDescriptors = 4, flags = 0) " \
   ")"
 [shader("compute"), RootSignature(SampleDescriptorTable)]
 [numthreads(1,1,1)]

llvm/lib/Frontend/HLSL/HLSLRootSignature.cpp

@@ -196,7 +196,16 @@ MDNode *MetadataBuilder::BuildRootSignature() {
 }
 
 MDNode *MetadataBuilder::BuildDescriptorTable(const DescriptorTable &Table) {
-  return MDNode::get(Ctx, {MDString::get(Ctx, "DescriptorTable")});
+  IRBuilder<> B(Ctx);
+  SmallVector<Metadata *> TableOperands;
+  TableOperands.push_back(MDString::get(Ctx, "DescriptorTable"));
+  TableOperands.push_back(ConstantAsMetadata::get(B.getInt32(llvm::to_underlying(Table.Visibility))));
+
+  assert(Table.NumClauses <= GeneratedMetadata.size() && "Table expected all owned clauses to be generated already");
+  TableOperands.append(GeneratedMetadata.end() - Table.NumClauses, GeneratedMetadata.end());
+  GeneratedMetadata.pop_back_n(Table.NumClauses);
+
+  return MDNode::get(Ctx, TableOperands);
 }
 
 MDNode *MetadataBuilder::BuildDescriptorTableClause(const DescriptorTableClause &Clause) {