[HLSL] Implement RWBuffer::operator[] via __builtin_hlsl_resource_getpointer

clang/include/clang/Basic/Builtins.td

@@ -4738,6 +4738,12 @@ def GetDeviceSideMangledName : LangBuiltin<"CUDA_LANG"> {
 }
 
 // HLSL
+def HLSLResourceGetPointer : LangBuiltin<"HLSL_LANG"> {
+  let Spellings = ["__builtin_hlsl_resource_getpointer"];
+  let Attributes = [NoThrow];
+  let Prototype = "void(...)";
+}
+
 def HLSLAll : LangBuiltin<"HLSL_LANG"> {
   let Spellings = ["__builtin_hlsl_all"];
   let Attributes = [NoThrow, Const];

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -12496,6 +12496,7 @@ def err_hlsl_pointers_unsupported : Error<
   "%select{pointers|references}0 are unsupported in HLSL">;
 def err_hlsl_missing_resource_class : Error<"HLSL resource needs to have [[hlsl::resource_class()]] attribute">;
 def err_hlsl_attribute_needs_intangible_type: Error<"attribute %0 can be used only on HLSL intangible type %1">;
+def err_hlsl_builtin_requires_resource: Error<"operand must be of __hlsl_resource_t type">;
 
 def err_hlsl_operator_unsupported : Error<
   "the '%select{&|*|->}0' operator is unsupported in HLSL">;

clang/lib/AST/Type.cpp

@@ -4723,7 +4723,9 @@ LinkageInfo LinkageComputer::computeTypeLinkageInfo(const Type *T) {
   case Type::Pipe:
     return computeTypeLinkageInfo(cast<PipeType>(T)->getElementType());
   case Type::HLSLAttributedResource:
-    llvm_unreachable("not yet implemented");
+    return computeTypeLinkageInfo(cast<HLSLAttributedResourceType>(T)
+                                      ->getContainedType()
+                                      ->getCanonicalTypeInternal());
   }
 
   llvm_unreachable("unhandled type class");

clang/lib/CodeGen/CGBuiltin.cpp

@@ -19044,6 +19044,16 @@ Value *CodeGenFunction::EmitHLSLBuiltinExpr(unsigned BuiltinID,
     return nullptr;
 
   switch (BuiltinID) {
+  case Builtin::BI__builtin_hlsl_resource_getpointer: {
+    Value *HandleOp = EmitScalarExpr(E->getArg(0));
+    Value *IndexOp = EmitScalarExpr(E->getArg(1));
+
+    // TODO: Map to an hlsl_device address space.
+    llvm::Type *RetTy = llvm::PointerType::getUnqual(getLLVMContext());
+
+    return Builder.CreateIntrinsic(RetTy, Intrinsic::dx_resource_getpointer,
+                                   ArrayRef<Value *>{HandleOp, IndexOp});
+  }
   case Builtin::BI__builtin_hlsl_all: {
     Value *Op0 = EmitScalarExpr(E->getArg(0));
     return Builder.CreateIntrinsic(

clang/lib/Sema/HLSLExternalSemaSource.cpp

@@ -123,12 +123,8 @@ struct BuiltinTypeDeclBuilder {
     assert(!Record->isCompleteDefinition() && "record is already complete");
 
     ASTContext &Ctx = SemaRef.getASTContext();
-    TypeSourceInfo *ElementTypeInfo = nullptr;
-
-    QualType ElemTy = Ctx.Char8Ty;
-    if (Template)
-      ElemTy = getFirstTemplateTypeParam();
-    ElementTypeInfo = Ctx.getTrivialTypeSourceInfo(ElemTy, SourceLocation());
+    TypeSourceInfo *ElementTypeInfo =
+        Ctx.getTrivialTypeSourceInfo(getHandleElementType(), SourceLocation());
 
     // add handle member with resource type attributes
     QualType AttributedResTy = QualType();
@@ -171,80 +167,12 @@ struct BuiltinTypeDeclBuilder {
   }
 
   BuiltinTypeDeclBuilder &addArraySubscriptOperators() {
-    addArraySubscriptOperator(true);
-    addArraySubscriptOperator(false);
-    return *this;
-  }
-
-  BuiltinTypeDeclBuilder &addArraySubscriptOperator(bool IsConst) {
-    assert(!Record->isCompleteDefinition() && "record is already complete");
-
     ASTContext &AST = Record->getASTContext();
-    QualType ElemTy = AST.Char8Ty;
-    if (Template)
-      ElemTy = getFirstTemplateTypeParam();
-    QualType ReturnTy = ElemTy;
-
-    FunctionProtoType::ExtProtoInfo ExtInfo;
-
-    // Subscript operators return references to elements, const makes the
-    // reference and method const so that the underlying data is not mutable.
-    if (IsConst) {
-      ExtInfo.TypeQuals.addConst();
-      ReturnTy.addConst();
-    }
-    ReturnTy = AST.getLValueReferenceType(ReturnTy);
-
-    QualType MethodTy =
-        AST.getFunctionType(ReturnTy, {AST.UnsignedIntTy}, ExtInfo);
-    auto *TSInfo = AST.getTrivialTypeSourceInfo(MethodTy, SourceLocation());
-    auto *MethodDecl = CXXMethodDecl::Create(
-        AST, Record, SourceLocation(),
-        DeclarationNameInfo(
-            AST.DeclarationNames.getCXXOperatorName(OO_Subscript),
-            SourceLocation()),
-        MethodTy, TSInfo, SC_None, false, false, ConstexprSpecKind::Unspecified,
-        SourceLocation());
-
-    IdentifierInfo &II = AST.Idents.get("Idx", tok::TokenKind::identifier);
-    auto *IdxParam = ParmVarDecl::Create(
-        AST, MethodDecl->getDeclContext(), SourceLocation(), SourceLocation(),
-        &II, AST.UnsignedIntTy,
-        AST.getTrivialTypeSourceInfo(AST.UnsignedIntTy, SourceLocation()),
-        SC_None, nullptr);
-    MethodDecl->setParams({IdxParam});
-
-    // Also add the parameter to the function prototype.
-    auto FnProtoLoc = TSInfo->getTypeLoc().getAs<FunctionProtoTypeLoc>();
-    FnProtoLoc.setParam(0, IdxParam);
-
-    // FIXME: Placeholder to make sure we return the correct type - create
-    // field of element_type and return reference to it. This field will go
-    // away once indexing into resources is properly implemented in
-    // llvm/llvm-project#95956.
-    if (Fields.count("e") == 0) {
-      addMemberVariable("e", ElemTy, {});
-    }
-    FieldDecl *ElemFieldDecl = Fields["e"];
-
-    auto *This =
-        CXXThisExpr::Create(AST, SourceLocation(),
-                            MethodDecl->getFunctionObjectParameterType(), true);
-    Expr *ElemField = MemberExpr::CreateImplicit(
-        AST, This, false, ElemFieldDecl, ElemFieldDecl->getType(), VK_LValue,
-        OK_Ordinary);
-    auto *Return =
-        ReturnStmt::Create(AST, SourceLocation(), ElemField, nullptr);
-
-    MethodDecl->setBody(CompoundStmt::Create(AST, {Return}, FPOptionsOverride(),
-                                             SourceLocation(),
-                                             SourceLocation()));
-    MethodDecl->setLexicalDeclContext(Record);
-    MethodDecl->setAccess(AccessSpecifier::AS_public);
-    MethodDecl->addAttr(AlwaysInlineAttr::CreateImplicit(
-        AST, SourceRange(), AlwaysInlineAttr::CXX11_clang_always_inline));
-    Record->addDecl(MethodDecl);
+    DeclarationName Subscript =
+        AST.DeclarationNames.getCXXOperatorName(OO_Subscript);
 
+    addHandleAccessFunction(Subscript, /*IsConst=*/true, /*IsRef=*/true);
+    addHandleAccessFunction(Subscript, /*IsConst=*/false, /*IsRef=*/true);
     return *this;
   }
 
@@ -265,6 +193,13 @@ struct BuiltinTypeDeclBuilder {
     return QualType();
   }
 
+  QualType getHandleElementType() {
+    if (Template)
+      return getFirstTemplateTypeParam();
+    // TODO: Should we default to VoidTy? Using `i8` is arguably ambiguous.
+    return SemaRef.getASTContext().Char8Ty;
+  }
+
   BuiltinTypeDeclBuilder &startDefinition() {
     assert(!Record->isCompleteDefinition() && "record is already complete");
     Record->startDefinition();
@@ -294,6 +229,8 @@ struct BuiltinTypeDeclBuilder {
   // Builtin types methods
   BuiltinTypeDeclBuilder &addIncrementCounterMethod();
   BuiltinTypeDeclBuilder &addDecrementCounterMethod();
+  BuiltinTypeDeclBuilder &addHandleAccessFunction(DeclarationName &Name,
+                                                  bool IsConst, bool IsRef);
 };
 
 struct TemplateParameterListBuilder {
@@ -453,7 +390,7 @@ struct TemplateParameterListBuilder {
 // Builder for methods of builtin types. Allows adding methods to builtin types
 // using the builder pattern like this:
 //
-//   BuiltinTypeMethodBuilder(Sema, RecordBuilder, "MethodName", ReturnType)
+//   BuiltinTypeMethodBuilder(RecordBuilder, "MethodName", ReturnType)
 //       .addParam("param_name", Type, InOutModifier)
 //       .callBuiltin("builtin_name", BuiltinParams...)
 //       .finalizeMethod();
@@ -486,6 +423,7 @@ struct BuiltinTypeMethodBuilder {
   DeclarationNameInfo NameInfo;
   QualType ReturnTy;
   CXXMethodDecl *Method;
+  bool IsConst;
   llvm::SmallVector<MethodParam> Params;
   llvm::SmallVector<Stmt *> StmtsList;
 
@@ -508,11 +446,16 @@ struct BuiltinTypeMethodBuilder {
   Expr *convertPlaceholder(Expr *E) { return E; }
 
 public:
-  BuiltinTypeMethodBuilder(Sema &S, BuiltinTypeDeclBuilder &DB, StringRef Name,
-                           QualType ReturnTy)
-      : DeclBuilder(DB), ReturnTy(ReturnTy), Method(nullptr) {
+  BuiltinTypeMethodBuilder(BuiltinTypeDeclBuilder &DB, DeclarationName &Name,
+                           QualType ReturnTy, bool IsConst = false)
+      : DeclBuilder(DB), NameInfo(DeclarationNameInfo(Name, SourceLocation())),
+        ReturnTy(ReturnTy), Method(nullptr), IsConst(IsConst) {}
+
+  BuiltinTypeMethodBuilder(BuiltinTypeDeclBuilder &DB, StringRef Name,
+                           QualType ReturnTy, bool IsConst = false)
+      : DeclBuilder(DB), ReturnTy(ReturnTy), Method(nullptr), IsConst(IsConst) {
     const IdentifierInfo &II =
-        S.getASTContext().Idents.get(Name, tok::TokenKind::identifier);
+        DB.SemaRef.getASTContext().Idents.get(Name, tok::TokenKind::identifier);
     NameInfo = DeclarationNameInfo(DeclarationName(&II), SourceLocation());
   }
 
@@ -535,8 +478,12 @@ struct BuiltinTypeMethodBuilder {
     SmallVector<QualType> ParamTypes;
     for (MethodParam &MP : Params)
       ParamTypes.emplace_back(MP.Ty);
-    QualType MethodTy = AST.getFunctionType(ReturnTy, ParamTypes,
-                                            FunctionProtoType::ExtProtoInfo());
+
+    FunctionProtoType::ExtProtoInfo ExtInfo;
+    if (IsConst)
+      ExtInfo.TypeQuals.addConst();
+
+    QualType MethodTy = AST.getFunctionType(ReturnTy, ParamTypes, ExtInfo);
 
     // create method decl
     auto *TSInfo = AST.getTrivialTypeSourceInfo(MethodTy, SourceLocation());
@@ -586,7 +533,8 @@ struct BuiltinTypeMethodBuilder {
   }
 
   template <typename... Ts>
-  BuiltinTypeMethodBuilder &callBuiltin(StringRef BuiltinName, Ts... ArgSpecs) {
+  BuiltinTypeMethodBuilder &callBuiltin(StringRef BuiltinName,
+                                        QualType ReturnType, Ts... ArgSpecs) {
     std::array<Expr *, sizeof...(ArgSpecs)> Args{
         convertPlaceholder(std::forward<Ts>(ArgSpecs))...};
 
@@ -599,15 +547,32 @@ struct BuiltinTypeMethodBuilder {
     FunctionDecl *FD = lookupBuiltinFunction(DeclBuilder.SemaRef, BuiltinName);
     DeclRefExpr *DRE = DeclRefExpr::Create(
         AST, NestedNameSpecifierLoc(), SourceLocation(), FD, false,
-        FD->getNameInfo(), FD->getType(), VK_PRValue);
+        FD->getNameInfo(), AST.BuiltinFnTy, VK_PRValue);
+
+    if (ReturnType.isNull())
+      ReturnType = FD->getReturnType();
 
-    Expr *Call =
-        CallExpr::Create(AST, DRE, Args, FD->getReturnType(), VK_PRValue,
-                         SourceLocation(), FPOptionsOverride());
+    Expr *Call = CallExpr::Create(AST, DRE, Args, ReturnType, VK_PRValue,
+                                  SourceLocation(), FPOptionsOverride());
     StmtsList.push_back(Call);
     return *this;
   }
 
+  BuiltinTypeMethodBuilder &dereference() {
+    assert(!StmtsList.empty() && "Nothing to dereference");
+    ASTContext &AST = DeclBuilder.SemaRef.getASTContext();
+
+    Expr *LastExpr = dyn_cast<Expr>(StmtsList.back());
+    assert(LastExpr && "No expression to dereference");
+    Expr *Deref = UnaryOperator::Create(
+        AST, LastExpr, UO_Deref, LastExpr->getType()->getPointeeType(),
+        VK_PRValue, OK_Ordinary, SourceLocation(),
+        /*CanOverflow=*/false, FPOptionsOverride());
+    StmtsList.pop_back();
+    StmtsList.push_back(Deref);
+    return *this;
+  }
+
   BuiltinTypeDeclBuilder &finalizeMethod() {
     assert(!DeclBuilder.Record->isCompleteDefinition() &&
            "record is already complete");
@@ -621,11 +586,8 @@ struct BuiltinTypeMethodBuilder {
              "nothing to return from non-void method");
       if (ReturnTy != AST.VoidTy) {
         if (Expr *LastExpr = dyn_cast<Expr>(StmtsList.back())) {
-          assert(AST.hasSameUnqualifiedType(
-                     isa<CallExpr>(LastExpr)
-                         ? cast<CallExpr>(LastExpr)->getCallReturnType(AST)
-                         : LastExpr->getType(),
-                     ReturnTy) &&
+          assert(AST.hasSameUnqualifiedType(LastExpr->getType(),
+                                            ReturnTy.getNonReferenceType()) &&
                  "Return type of the last statement must match the return type "
                  "of the method");
           if (!isa<ReturnStmt>(LastExpr)) {
@@ -672,19 +634,43 @@ BuiltinTypeDeclBuilder::addSimpleTemplateParams(ArrayRef<StringRef> Names,
 
 BuiltinTypeDeclBuilder &BuiltinTypeDeclBuilder::addIncrementCounterMethod() {
   using PH = BuiltinTypeMethodBuilder::PlaceHolder;
-  return BuiltinTypeMethodBuilder(SemaRef, *this, "IncrementCounter",
+  return BuiltinTypeMethodBuilder(*this, "IncrementCounter",
                                   SemaRef.getASTContext().UnsignedIntTy)
-      .callBuiltin("__builtin_hlsl_buffer_update_counter", PH::Handle,
-                   getConstantIntExpr(1))
+      .callBuiltin("__builtin_hlsl_buffer_update_counter", QualType(),
+                   PH::Handle, getConstantIntExpr(1))
       .finalizeMethod();
 }
 
 BuiltinTypeDeclBuilder &BuiltinTypeDeclBuilder::addDecrementCounterMethod() {
   using PH = BuiltinTypeMethodBuilder::PlaceHolder;
-  return BuiltinTypeMethodBuilder(SemaRef, *this, "DecrementCounter",
+  return BuiltinTypeMethodBuilder(*this, "DecrementCounter",
                                   SemaRef.getASTContext().UnsignedIntTy)
-      .callBuiltin("__builtin_hlsl_buffer_update_counter", PH::Handle,
-                   getConstantIntExpr(-1))
+      .callBuiltin("__builtin_hlsl_buffer_update_counter", QualType(),
+                   PH::Handle, getConstantIntExpr(-1))
+      .finalizeMethod();
+}
+
+BuiltinTypeDeclBuilder &
+BuiltinTypeDeclBuilder::addHandleAccessFunction(DeclarationName &Name,
+                                                bool IsConst, bool IsRef) {
+  assert(!Record->isCompleteDefinition() && "record is already complete");
+  ASTContext &AST = SemaRef.getASTContext();
+  using PH = BuiltinTypeMethodBuilder::PlaceHolder;
+
+  QualType ElemTy = getHandleElementType();
+  // TODO: Map to an hlsl_device address space.
+  QualType ElemPtrTy = AST.getPointerType(ElemTy);
+  QualType ReturnTy = ElemTy;
+  if (IsConst)
+    ReturnTy.addConst();
+  if (IsRef)
+    ReturnTy = AST.getLValueReferenceType(ReturnTy);
+
+  return BuiltinTypeMethodBuilder(*this, Name, ReturnTy, IsConst)
+      .addParam("Index", AST.UnsignedIntTy)
+      .callBuiltin("__builtin_hlsl_resource_getpointer", ElemPtrTy, PH::Handle,
+                   PH::_0)
+      .dereference()
       .finalizeMethod();
 }
 

clang/lib/Sema/SemaExpr.cpp

@@ -980,6 +980,9 @@ Sema::VarArgKind Sema::isValidVarArgType(const QualType &Ty) {
   if (Ty->isObjCObjectType())
     return VAK_Invalid;
 
+  if (getLangOpts().HLSL && Ty->getAs<HLSLAttributedResourceType>())
+    return VAK_Valid;
+
   if (getLangOpts().MSVCCompat)
     return VAK_MSVCUndefined;
 

clang/lib/Sema/SemaHLSL.cpp

@@ -1926,6 +1926,25 @@ static bool CheckResourceHandle(
 // returning an ExprError
 bool SemaHLSL::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
   switch (BuiltinID) {
+  case Builtin::BI__builtin_hlsl_resource_getpointer: {
+    if (SemaRef.checkArgCount(TheCall, 2))
+      return true;
+    auto *ResourceTy =
+        TheCall->getArg(0)->getType()->getAs<HLSLAttributedResourceType>();
+    if (!ResourceTy) {
+      SemaRef.Diag(TheCall->getBeginLoc(),
+                   diag::err_hlsl_builtin_requires_resource)
+          << TheCall->getArg(0)->getSourceRange();
+      return true;
+    }
+
+    QualType ContainedTy = ResourceTy->getContainedType();
+    // TODO: Map to an hlsl_device address space.
+    TheCall->setType(getASTContext().getPointerType(ContainedTy));
+    TheCall->setValueKind(VK_LValue);
+
+    break;
+  }
   case Builtin::BI__builtin_hlsl_all:
   case Builtin::BI__builtin_hlsl_any: {
     if (SemaRef.checkArgCount(TheCall, 1))