[clang] [HLSL] Add implicit resource element type concepts to AST (PR #112600)

[Helena Kotas via cfe-commits]

================
@@ -483,10 +582,101 @@ static BuiltinTypeDeclBuilder setupBufferType(CXXRecordDecl *Decl, Sema &S,
       .addDefaultHandleConstructor(S, RC);
 }
 
+BinaryOperator *constructSizeOfLEQ16Expr(ASTContext &Context,
+                                         SourceLocation NameLoc,
+                                         TemplateTypeParmDecl *T) {
+  // Obtain the QualType for 'unsigned long'
+  QualType UnsignedLongType = Context.UnsignedLongTy;
+
+  // Create a QualType that points to this TemplateTypeParmDecl
+  QualType TType = Context.getTypeDeclType(T);
+
+  // Create a TypeSourceInfo for the template type parameter 'T'
+  TypeSourceInfo *TTypeSourceInfo =
+      Context.getTrivialTypeSourceInfo(TType, NameLoc);
+
+  UnaryExprOrTypeTraitExpr *sizeOfExpr = new (Context) UnaryExprOrTypeTraitExpr(
+      UETT_SizeOf, TTypeSourceInfo, UnsignedLongType, NameLoc, NameLoc);
+
+  // Create an IntegerLiteral for the value '16' with size type
+  QualType SizeType = Context.getSizeType();
+  llvm::APInt SizeValue = llvm::APInt(Context.getTypeSize(SizeType), 16);
+  IntegerLiteral *SizeLiteral =
+      new (Context) IntegerLiteral(Context, SizeValue, SizeType, NameLoc);
+
+  QualType BoolTy = Context.BoolTy;
+
+  BinaryOperator *binaryOperator =
+      BinaryOperator::Create(Context, sizeOfExpr, // Left-hand side expression
+                             SizeLiteral,         // Right-hand side expression
+                             BO_LE,               // Binary operator kind (<=)
+                             BoolTy,              // Result type (bool)
+                             VK_LValue,           // Value kind
+                             OK_Ordinary,         // Object kind
+                             NameLoc,             // Source location of operator
+                             FPOptionsOverride());
+
+  return binaryOperator;
+}
+
+Expr *constructTypedBufferConstraintExpr(Sema &S, SourceLocation NameLoc,
+                                         TemplateTypeParmDecl *T) {
+  ASTContext &Context = S.getASTContext();
+
+  // first get the "sizeof(T) <= 16" expression, as a binary operator
+  BinaryOperator *SizeOfLEQ16 = constructSizeOfLEQ16Expr(Context, NameLoc, T);
+  // TODO: add the '__builtin_hlsl_is_line_vector_layout_compatible' builtin
+  // and return a binary operator that evaluates the builtin on the given
+  // template type parameter 'T'
+  return SizeOfLEQ16;
+}
+
+ConceptDecl *constructTypedBufferConceptDecl(Sema &S) {
+  DeclContext *DC = S.CurContext;
+  ASTContext &Context = S.getASTContext();
+  SourceLocation DeclLoc = SourceLocation();
+
+  IdentifierInfo &IsValidLineVectorII =
+      Context.Idents.get("is_valid_line_vector");
+  IdentifierInfo &ElementTypeII = Context.Idents.get("element_type");
+  TemplateTypeParmDecl *T = TemplateTypeParmDecl::Create(
+      Context, Context.getTranslationUnitDecl(), DeclLoc, DeclLoc,
+      /*depth=*/0,
+      /*position=*/0,
+      /*id=*/&ElementTypeII,
+      /*Typename=*/true,
+      /*ParameterPack=*/false);
+
+  T->setDeclContext(DC);
+  T->setReferenced();
+
+  // Create and Attach Template Parameter List to ConceptDecl
+  TemplateParameterList *ConceptParams = TemplateParameterList::Create(
+      Context, DeclLoc, DeclLoc, {T}, DeclLoc, nullptr);
+
+  DeclarationName DeclName = DeclarationName(&IsValidLineVectorII);
+  Expr *ConstraintExpr = constructTypedBufferConstraintExpr(S, DeclLoc, T);
+
+  // Create a ConceptDecl
+  ConceptDecl *CD =
+      ConceptDecl::Create(Context, Context.getTranslationUnitDecl(), DeclLoc,
+                          DeclName, ConceptParams, ConstraintExpr);
+
+  // Attach the template parameter list to the ConceptDecl
+  CD->setTemplateParameters(ConceptParams);
+
+  // Add the concept declaration to the Translation Unit Decl
+  Context.getTranslationUnitDecl()->addDecl(CD);
+
+  return CD;
+}
+
 void HLSLExternalSemaSource::defineHLSLTypesWithForwardDeclarations() {
   CXXRecordDecl *Decl;
+  ConceptDecl *CD = constructTypedBufferConceptDecl(*SemaPtr);
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hekota wrote:

I'd probably use a more descriptive name here, like `TypeBufferConcept` since as we'll need to have one for RawBuffers as well, right?

https://github.com/llvm/llvm-project/pull/112600