[HLSL] Add HLSLResource attribute

HLSL Resource objects will have restrictions on use and codegen
requirements. This patch is fairly minimal just adding the attribute
with no spellings since it will only be attached by the
HLSLExternalSemaSource.

Depends on D1300017.

Differential Revision: https://reviews.llvm.org/D130018

Author: llvm-beanz

clang/include/clang/Basic/Attr.td

@@ -4022,6 +4022,17 @@ def HLSLShader : InheritableAttr {
   let Documentation = [HLSLSV_ShaderTypeAttrDocs];
 }
 
+def HLSLResource : InheritableAttr {
+  let Spellings = [];
+  let Subjects = SubjectList<[Struct]>;
+  let LangOpts = [HLSL];
+  let Args = [EnumArgument<"ResourceType", "ResourceClass",
+                           ["SRV", "UAV", "CBuffer", "Sampler"],
+                           ["SRV", "UAV", "CBuffer", "Sampler"]
+                           >];
+  let Documentation = [InternalOnly];
+}
+
 def RandomizeLayout : InheritableAttr {
   let Spellings = [GCC<"randomize_layout">];
   let Subjects = SubjectList<[Record]>;

clang/lib/Sema/HLSLExternalSemaSource.cpp

@@ -107,6 +107,13 @@ struct BuiltinTypeDeclBuilder {
     return addMemberVariable("h", Record->getASTContext().VoidPtrTy, Access);
   }
 
+  BuiltinTypeDeclBuilder &
+  annotateResourceClass(HLSLResourceAttr::ResourceClass RC) {
+    Record->addAttr(
+        HLSLResourceAttr::CreateImplicit(Record->getASTContext(), RC));
+    return *this;
+  }
+
   static DeclRefExpr *lookupBuiltinFunction(ASTContext &AST, Sema &S,
                                             StringRef Name) {
     CXXScopeSpec SS;
@@ -361,5 +368,6 @@ void HLSLExternalSemaSource::completeBufferType(CXXRecordDecl *Record) {
   BuiltinTypeDeclBuilder(Record)
       .addHandleMember()
       .addDefaultHandleConstructor(*SemaPtr, ResourceClass::UAV)
+      .annotateResourceClass(HLSLResourceAttr::UAV)
       .completeDefinition();
 }

clang/test/AST/HLSL/RWBuffer-AST.hlsl

@@ -38,10 +38,12 @@ RWBuffer<float> Buffer;
 // CHECK-NEXT: CXXRecordDecl 0x{{[0-9A-Fa-f]+}} <<invalid sloc>> <invalid sloc> implicit class RWBuffer definition
 
 // CHECK: FinalAttr 0x{{[0-9A-Fa-f]+}} <<invalid sloc>> Implicit final
+// CHECK-NEXT: HLSLResourceAttr 0x{{[0-9A-Fa-f]+}} <<invalid sloc>> Implicit UAV
 // CHECK-NEXT: FieldDecl 0x{{[0-9A-Fa-f]+}} <<invalid sloc>> <invalid sloc> implicit h 'void *'
 // CHECK: ClassTemplateSpecializationDecl 0x{{[0-9A-Fa-f]+}} <<invalid sloc>> <invalid sloc> class RWBuffer definition
 
 // CHECK: TemplateArgument type 'float'
 // CHECK-NEXT: BuiltinType 0x{{[0-9A-Fa-f]+}} 'float'
 // CHECK-NEXT: FinalAttr 0x{{[0-9A-Fa-f]+}} <<invalid sloc>> Implicit final
+// CHECK-NEXT: HLSLResourceAttr 0x{{[0-9A-Fa-f]+}} <<invalid sloc>> Implicit UAV
 // CHECK-NEXT: FieldDecl 0x{{[0-9A-Fa-f]+}} <<invalid sloc>> <invalid sloc>  implicit referenced h 'void *'