[llvm-branch-commits] [clang] [llvm] [HLSL] Generate semantic signature metadata (PR #212892)

[Justin Bogner via llvm-branch-commits]

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@@ -1226,13 +1257,64 @@ static SemanticShape getSemanticShape(ASTContext &Ctx, QualType Ty) {
   return {Rows, Cols, Ty};
 }
 
+static llvm::dxil::ElementType getSignatureComponentType(CodeGenModule &CGM,
+                                                         QualType Ty) {
+  if (const auto *VT = Ty->getAs<clang::VectorType>())
+    Ty = VT->getElementType();
+  else if (const auto *MT = Ty->getAs<clang::ConstantMatrixType>())
+    Ty = MT->getElementType();
+
+  llvm::Type *IRTy = CGM.getTypes().ConvertTypeForMem(Ty);
+  bool IsSigned = Ty->isSignedIntegerOrEnumerationType();
+  return llvm::dxil::toDXILElementType(IRTy, IsSigned);
+}
+
+static llvm::dxbc::PSV::SemanticKind
+getSignatureSemanticKind(StringRef SemanticName) {
+  if (!SemanticName.consume_front_insensitive("SV_"))
+    return llvm::dxbc::PSV::SemanticKind::Arbitrary;
+
+  for (const auto &Kind : llvm::dxbc::PSV::getSemanticKinds())
+    if (SemanticName.equals_insensitive(Kind.name()))
+      return Kind.value();
+
+  return llvm::dxbc::PSV::SemanticKind::Invalid;
+}
+
+static llvm::hlsl::SemanticSignatureElement createSemanticSignatureElement(
+    CodeGenModule &CGM, uint32_t SigId, HLSLAppliedSemanticAttr *Semantic,
+    std::optional<unsigned> Index, const SemanticShape &Shape) {
+  llvm::hlsl::SemanticSignatureElement Element{};
+  Element.SigId = SigId;
+  Element.SemanticName = Semantic->getAttrName()->getName();
+  Element.CompType = getSignatureComponentType(CGM, Shape.RowType);
+  Element.SemanticKind = getSignatureSemanticKind(Element.SemanticName);
+  Element.Rows = Shape.Rows;
+  Element.Cols = static_cast<uint8_t>(Shape.Cols);
+  // All members with a default value will be filled at a later stage, either
+  // during packing or analysis of usage
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bogner wrote:

Can we add a constructor to `SemanticSignatureElement` that initializes all of the fields that don't have defaults? This pattern of initialization feels error-prone. I guess we'd still need a constructor that leaves everything uninitialized for the `fromMetadata` case, but I think it's fine to have both.

https://github.com/llvm/llvm-project/pull/212892