Add a new expression kind, OpaqueValueExpr, which is useful for

certain internal type-checking procedures as well as for representing
certain implicitly-generated operations.  Uses to follow.

llvm-svn: 119289

clang/include/clang/AST/Expr.h

@@ -3509,6 +3509,35 @@ public:
   virtual child_iterator child_end();
 };
 
+/// OpaqueValueExpr - An expression referring to an opaque object of a
+/// fixed type and value class.  These don't correspond to concrete
+/// syntax; instead they're used to express operations (usually copy
+/// operations) on values whose source is generally obvious from
+/// context.
+class OpaqueValueExpr : public Expr {
+  friend class ASTStmtReader;
+public:
+  OpaqueValueExpr(QualType T, ExprValueKind VK)
+    : Expr(OpaqueValueExprClass, T, T->isDependentType(),
+           T->isDependentType()) {
+    setValueKind(VK);
+  }
+
+  explicit OpaqueValueExpr(EmptyShell Empty)
+    : Expr(OpaqueValueExprClass, Empty) { }
+
+  using Expr::getValueKind;
+
+  virtual SourceRange getSourceRange() const;
+  virtual child_iterator child_begin();
+  virtual child_iterator child_end();
+
+  static bool classof(const Stmt *T) {
+    return T->getStmtClass() == OpaqueValueExprClass;
+  }
+  static bool classof(const OpaqueValueExpr *) { return true; }
+};
+
 }  // end namespace clang
 
 #endif

clang/include/clang/AST/RecursiveASTVisitor.h

@@ -1791,6 +1791,7 @@ DEF_TRAVERSE_STMT(StmtExpr, { })
 DEF_TRAVERSE_STMT(UnresolvedLookupExpr, { })
 DEF_TRAVERSE_STMT(UnresolvedMemberExpr, { })
 DEF_TRAVERSE_STMT(CXXOperatorCallExpr, { })
+DEF_TRAVERSE_STMT(OpaqueValueExpr, { })
 
 // These operators (all of them) do not need any action except
 // iterating over the children.

clang/include/clang/Basic/StmtNodes.td

@@ -127,6 +127,7 @@ def ObjCIsaExpr : DStmt<Expr>;
 def ShuffleVectorExpr : DStmt<Expr>;
 def BlockExpr : DStmt<Expr>;
 def BlockDeclRefExpr : DStmt<Expr>;
+def OpaqueValueExpr : DStmt<Expr>;
 
 // Microsoft Extensions.
 def CXXUuidofExpr : DStmt<Expr>; 

clang/include/clang/Serialization/ASTBitCodes.h

@@ -922,7 +922,9 @@ namespace clang {
       EXPR_CXX_UNRESOLVED_LOOKUP,        // UnresolvedLookupExpr
 
       EXPR_CXX_UNARY_TYPE_TRAIT,  // UnaryTypeTraitExpr
-      EXPR_CXX_NOEXCEPT           // CXXNoexceptExpr
+      EXPR_CXX_NOEXCEPT,          // CXXNoexceptExpr
+
+      EXPR_OPAQUE_VALUE           // OpaqueValueExpr
     };
 
     /// \brief The kinds of designators that can occur in a

clang/lib/AST/Expr.cpp

@@ -2709,3 +2709,9 @@ Stmt::child_iterator BlockExpr::child_end() { return child_iterator(); }
 
 Stmt::child_iterator BlockDeclRefExpr::child_begin() { return child_iterator();}
 Stmt::child_iterator BlockDeclRefExpr::child_end() { return child_iterator(); }
+
+// OpaqueValueExpr
+SourceRange OpaqueValueExpr::getSourceRange() const { return SourceRange(); }
+Stmt::child_iterator OpaqueValueExpr::child_begin() { return child_iterator(); }
+Stmt::child_iterator OpaqueValueExpr::child_end() { return child_iterator(); }
+

clang/lib/AST/ExprClassification.cpp

@@ -33,6 +33,22 @@ static Cl::Kinds ClassifyConditional(ASTContext &Ctx,
 static Cl::ModifiableType IsModifiable(ASTContext &Ctx, const Expr *E,
                                        Cl::Kinds Kind, SourceLocation &Loc);
 
+static Cl::Kinds ClassifyExprValueKind(const LangOptions &Lang,
+                                       const Expr *E,
+                                       ExprValueKind Kind) {
+  switch (Kind) {
+  case VK_RValue:
+    return Lang.CPlusPlus && E->getType()->isRecordType() ?
+      Cl::CL_ClassTemporary : Cl::CL_PRValue;
+  case VK_LValue:
+    return Cl::CL_LValue;
+  case VK_XValue:
+    return Cl::CL_XValue;
+  }
+  llvm_unreachable("Invalid value category of implicit cast.");
+  return Cl::CL_PRValue;
+}
+
 Cl Expr::ClassifyImpl(ASTContext &Ctx, SourceLocation *Loc) const {
   assert(!TR->isReferenceType() && "Expressions can't have reference type.");
 
@@ -171,19 +187,15 @@ static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E) {
       return Cl::CL_PRValue;
     }
 
+  case Expr::OpaqueValueExprClass:
+    return ClassifyExprValueKind(Lang, E,
+                                 cast<OpaqueValueExpr>(E)->getValueKind());
+
     // Implicit casts are lvalues if they're lvalue casts. Other than that, we
     // only specifically record class temporaries.
   case Expr::ImplicitCastExprClass:
-    switch (cast<ImplicitCastExpr>(E)->getValueKind()) {
-    case VK_RValue:
-      return Lang.CPlusPlus && E->getType()->isRecordType() ?
-        Cl::CL_ClassTemporary : Cl::CL_PRValue;
-    case VK_LValue:
-      return Cl::CL_LValue;
-    case VK_XValue:
-      return Cl::CL_XValue;
-    }
-    llvm_unreachable("Invalid value category of implicit cast.");
+    return ClassifyExprValueKind(Lang, E,
+                                 cast<ImplicitCastExpr>(E)->getValueKind());
 
     // C++ [expr.prim.general]p4: The presence of parentheses does not affect
     //   whether the expression is an lvalue.

clang/lib/AST/ExprConstant.cpp

@@ -2541,6 +2541,7 @@ static ICEDiag CheckICE(const Expr* E, ASTContext &Ctx) {
   case Expr::BlockExprClass:
   case Expr::BlockDeclRefExprClass:
   case Expr::NoStmtClass:
+  case Expr::OpaqueValueExprClass:
     return ICEDiag(2, E->getLocStart());
 
   case Expr::GNUNullExprClass:

clang/lib/AST/StmtPrinter.cpp

@@ -1335,6 +1335,9 @@ void StmtPrinter::VisitBlockExpr(BlockExpr *Node) {
 void StmtPrinter::VisitBlockDeclRefExpr(BlockDeclRefExpr *Node) {
   OS << Node->getDecl();
 }
+
+void StmtPrinter::VisitOpaqueValueExpr(OpaqueValueExpr *Node) {}
+
 //===----------------------------------------------------------------------===//
 // Stmt method implementations
 //===----------------------------------------------------------------------===//

clang/lib/AST/StmtProfile.cpp

@@ -834,6 +834,10 @@ void StmtProfiler::VisitCXXNoexceptExpr(CXXNoexceptExpr *S) {
   VisitExpr(S);
 }
 
+void StmtProfiler::VisitOpaqueValueExpr(OpaqueValueExpr *E) {
+  VisitExpr(E);  
+}
+
 void StmtProfiler::VisitObjCStringLiteral(ObjCStringLiteral *S) {
   VisitExpr(S);
 }

clang/lib/Checker/GRExprEngine.cpp

@@ -744,6 +744,7 @@ void GRExprEngine::Visit(const Stmt* S, ExplodedNode* Pred,
     case Stmt::NoStmtClass:
     case Stmt::NullStmtClass:
     case Stmt::SwitchCaseClass:
+    case Stmt::OpaqueValueExprClass:
       llvm_unreachable("Stmt should not be in analyzer evaluation loop");
       break;
 

clang/lib/CodeGen/Mangle.cpp

@@ -1681,6 +1681,9 @@ void CXXNameMangler::mangleExpression(const Expr *E, unsigned Arity) {
     break;
   }
 
+  case Expr::OpaqueValueExprClass:
+    llvm_unreachable("cannot mangle opaque value; mangling wrong thing?");
+
   case Expr::CXXDefaultArgExprClass:
     mangleExpression(cast<CXXDefaultArgExpr>(E)->getExpr(), Arity);
     break;

clang/lib/Sema/TreeTransform.h

@@ -4442,6 +4442,14 @@ TreeTransform<Derived>::TransformOffsetOfExpr(OffsetOfExpr *E) {
                                           E->getRParenLoc());
 }
 
+template<typename Derived>
+ExprResult
+TreeTransform<Derived>::TransformOpaqueValueExpr(OpaqueValueExpr *E) {
+  assert(getDerived().AlreadyTransformed(E->getType()) &&
+         "opaque value expression requires transformation");
+  return SemaRef.Owned(E);
+}
+
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformSizeOfAlignOfExpr(SizeOfAlignOfExpr *E) {

clang/lib/Serialization/ASTReaderStmt.cpp

@@ -178,6 +178,8 @@ namespace clang {
 
     void VisitUnaryTypeTraitExpr(UnaryTypeTraitExpr *E);
     void VisitCXXNoexceptExpr(CXXNoexceptExpr *E);
+
+    void VisitOpaqueValueExpr(OpaqueValueExpr *E);
   };
 }
 
@@ -1280,6 +1282,11 @@ void ASTStmtReader::VisitCXXNoexceptExpr(CXXNoexceptExpr *E) {
   E->Operand = Reader.ReadSubExpr();
 }
 
+void ASTStmtReader::VisitOpaqueValueExpr(OpaqueValueExpr *E) {
+  VisitExpr(E);
+  E->setValueKind(static_cast<ExprValueKind>(Record[Idx++]));
+}
+
 Stmt *ASTReader::ReadStmt(PerFileData &F) {
   switch (ReadingKind) {
   case Read_Decl:
@@ -1795,6 +1802,10 @@ Stmt *ASTReader::ReadStmtFromStream(PerFileData &F) {
     case EXPR_CXX_NOEXCEPT:
       S = new (Context) CXXNoexceptExpr(Empty);
       break;
+
+    case EXPR_OPAQUE_VALUE:
+      S = new (Context) OpaqueValueExpr(Empty);
+      break;
     }
     
     // We hit a STMT_STOP, so we're done with this expression.

clang/lib/Serialization/ASTWriterStmt.cpp

@@ -152,6 +152,8 @@ namespace clang {
 
     void VisitUnaryTypeTraitExpr(UnaryTypeTraitExpr *E);
     void VisitCXXNoexceptExpr(CXXNoexceptExpr *E);
+
+    void VisitOpaqueValueExpr(OpaqueValueExpr *E);
   };
 }
 
@@ -1293,6 +1295,12 @@ void ASTStmtWriter::VisitCXXNoexceptExpr(CXXNoexceptExpr *E) {
   Code = serialization::EXPR_CXX_NOEXCEPT;
 }
 
+void ASTStmtWriter::VisitOpaqueValueExpr(OpaqueValueExpr *E) {
+  VisitExpr(E);
+  Record.push_back(E->getValueKind());
+  Code = serialization::EXPR_OPAQUE_VALUE;
+}
+
 //===----------------------------------------------------------------------===//
 // ASTWriter Implementation
 //===----------------------------------------------------------------------===//

clang/tools/libclang/CXCursor.cpp

@@ -160,6 +160,7 @@ CXCursor cxcursor::MakeCXCursor(Stmt *S, Decl *Parent, ASTUnit *TU) {
   case Stmt::ObjCIsaExprClass:       
   case Stmt::ShuffleVectorExprClass: 
   case Stmt::BlockExprClass:  
+  case Stmt::OpaqueValueExprClass:
     K = CXCursor_UnexposedExpr;
     break;