[HLSL] Add HLSLResource attribute

[beanz]

Summary

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 D130017.

[aaron.ballman]

LGTM aside from a documentation question.

clang/include/clang/Basic/AttrDocs.td

6473–6475 ↗

(On Diff #445518)

Because the attribute cannot be written by the user, it seems like we shouldn't bother documenting this attribute at all. WDYT? If you agree, you can mark the attribute as Undocumented in Attr.td.

[beanz]

clang/include/clang/Basic/AttrDocs.td

6473–6475 ↗

(On Diff #445518)

Yea... I am kinda split mind on this myself, and I think the tl;dr is that this is the wrong place to document this.

The existing HLSL compiler and HLSL language are woefully short on documentation, so I'm trying to at least make a best-effort at documenting things as I implement them in clang. Since the AttrDocs are really intended to be user-facing documentation this is probably the wrong place to document it.

I'll pull this out and maybe separately create a folder under clang's docs directory for HLSL-related documentation so that it lives with the more project-centric docs. Does that make sense?

[aaron.ballman]

clang/include/clang/Basic/AttrDocs.td

6473–6475 ↗

(On Diff #445518)

I'll pull this out and maybe separately create a folder under clang's docs directory for HLSL-related documentation so that it lives with the more project-centric docs. Does that make sense?

I'm fine with that approach. FWIW, I've struggled with this a bit as well. We want all new attributes to be documented, and it's a sometimes super fuzzy line between "this is an implementation detail" and "users can use this with wild abandon". However, in this case, because the attribute has no spelling, it's pretty clearly an implementation detail. So putting that into the "using clang as a library" or other internal documentation.

clang/include/clang/Basic/Attr.td

let Args = [EnumArgument<"Type", "ShaderType",
                            ["Pixel", "Vertex", "Geometry", "Hull", "Domain",
                             "Compute", "RayGeneration", "Intersection",
                             "AnyHit", "ClosestHit", "Miss", "Callable", "Mesh",
                             "Amplification"]
                            >];
   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]>;
   let Documentation = [ClangRandomizeLayoutDocs];
   let LangOpts = [COnly];
 }
 
 def NoRandomizeLayout : InheritableAttr {

clang/lib/Sema/HLSLExternalSemaSource.cpp

addMemberVariable(StringRef Name, QualType Type,
     return *this;
   }
 
   BuiltinTypeDeclBuilder &
   addHandleMember(AccessSpecifier Access = AccessSpecifier::AS_private) {
     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;
     IdentifierInfo &II = AST.Idents.get(Name, tok::TokenKind::identifier);
     DeclarationNameInfo NameInfo =
         DeclarationNameInfo(DeclarationName(&II), SourceLocation());
     LookupResult R(S, NameInfo, Sema::LookupOrdinaryName);
     S.LookupParsedName(R, S.getCurScope(), &SS, false);
if (It == Completions.end())
     return;
   It->second(Record);
 }
 
 void HLSLExternalSemaSource::completeBufferType(CXXRecordDecl *Record) {
   BuiltinTypeDeclBuilder(Record)
       .addHandleMember()
       .addDefaultHandleConstructor(*SemaPtr, ResourceClass::UAV)
+      .annotateResourceClass(HLSLResourceAttr::UAV)
       .completeDefinition();
 }

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

 
 // CHECK: ClassTemplateDecl 0x{{[0-9A-Fa-f]+}} <<invalid sloc>> <invalid sloc> implicit RWBuffer
 // CHECK-NEXT: TemplateTypeParmDecl 0x{{[0-9A-Fa-f]+}} <<invalid sloc>> <invalid sloc> class depth 0 index 0 element_type
 // CHECK-NEXT: TemplateArgument type 'float'
 // CHECK-NEXT: BuiltinType 0x{{[0-9A-Fa-f]+}} 'float'
 // 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 *'