Change the AST representation of operations on Objective-C

property references to use a new PseudoObjectExpr
expression which pairs a syntactic form of the expression
with a set of semantic expressions implementing it.
This should significantly reduce the complexity required
elsewhere in the compiler to deal with these kinds of
expressions (e.g. IR generation's special l-value kind,
the static analyzer's Message abstraction), at the lower
cost of specifically dealing with the odd AST structure
of these expressions.  It should also greatly simplify
efforts to implement similar language features in the
future, most notably Managed C++'s properties and indexed
properties.

Most of the effort here is in dealing with the various
clients of the AST.  I've gone ahead and simplified the
ObjC rewriter's use of properties;  other clients, like
IR-gen and the static analyzer, have all the old
complexity *and* all the new complexity, at least
temporarily.  Many thanks to Ted for writing and advising
on the necessary changes to the static analyzer.

I've xfailed a small diagnostics regression in the static
analyzer at Ted's request.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@143867 91177308-0d34-0410-b5e6-96231b3b80d8

30 files changed, 1456 insertions, 650 deletions

diff --git a/lib/ARCMigrate/TransRetainReleaseDealloc.cpp b/lib/ARCMigrate/TransRetainReleaseDealloc.cpp
index bf2517f119..6eb82093cf 100644
--- a/lib/ARCMigrate/TransRetainReleaseDealloc.cpp
+++ b/lib/ARCMigrate/TransRetainReleaseDealloc.cpp
@@ -160,12 +160,14 @@ private:
     if (!E) return false;
 
     E = E->IgnoreParenCasts();
+
+    // Also look through property-getter sugar.
+    if (PseudoObjectExpr *pseudoOp = dyn_cast<PseudoObjectExpr>(E))
+      E = pseudoOp->getResultExpr()->IgnoreImplicit();
+
     if (ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E))
       return (ME->isInstanceMessage() && ME->getSelector() == DelegateSel);
 
-    if (ObjCPropertyRefExpr *propE = dyn_cast<ObjCPropertyRefExpr>(E))
-      return propE->getGetterSelector() == DelegateSel;
-
     return false;
   }
 
diff --git a/lib/ARCMigrate/TransUnbridgedCasts.cpp b/lib/ARCMigrate/TransUnbridgedCasts.cpp
index 69fb2e8949..3bfa15c6e0 100644
--- a/lib/ARCMigrate/TransUnbridgedCasts.cpp
+++ b/lib/ARCMigrate/TransUnbridgedCasts.cpp
@@ -236,7 +236,15 @@ private:
       }
     }
 
-    if (ImplicitCastExpr *implCE = dyn_cast<ImplicitCastExpr>(E->getSubExpr())){
+    Expr *subExpr = E->getSubExpr();
+
+    // Look through pseudo-object expressions.
+    if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(subExpr)) {
+      subExpr = pseudo->getResultExpr();
+      assert(subExpr && "no result for pseudo-object of non-void type?");
+    }
+
+    if (ImplicitCastExpr *implCE = dyn_cast<ImplicitCastExpr>(subExpr)) {
       if (implCE->getCastKind() == CK_ARCConsumeObject)
         return rewriteToBridgedCast(E, OBC_BridgeRetained);
       if (implCE->getCastKind() == CK_ARCReclaimReturnedObject)
diff --git a/lib/ARCMigrate/TransZeroOutPropsInDealloc.cpp b/lib/ARCMigrate/TransZeroOutPropsInDealloc.cpp
index 7c533bcf3a..d1f08aac28 100644
--- a/lib/ARCMigrate/TransZeroOutPropsInDealloc.cpp
+++ b/lib/ARCMigrate/TransZeroOutPropsInDealloc.cpp
@@ -78,6 +78,15 @@ public:
     return true;
   }
 
+  bool VisitPseudoObjectExpr(PseudoObjectExpr *POE) {
+    if (isZeroingPropIvar(POE) && isRemovable(POE)) {
+      Transaction Trans(Pass.TA);
+      Pass.TA.removeStmt(POE);
+    }
+
+    return true;
+  }
+
   bool VisitBinaryOperator(BinaryOperator *BOE) {
     if (isZeroingPropIvar(BOE) && isRemovable(BOE)) {
       Transaction Trans(Pass.TA);
@@ -142,17 +151,21 @@ private:
   }
 
   bool isZeroingPropIvar(Expr *E) {
-    BinaryOperator *BOE = dyn_cast_or_null<BinaryOperator>(E);
-    if (!BOE) return false;
+    E = E->IgnoreParens();
+    if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E))
+      return isZeroingPropIvar(BO);
+    if (PseudoObjectExpr *PO = dyn_cast<PseudoObjectExpr>(E))
+      return isZeroingPropIvar(PO);
+    return false;
+  }
 
+  bool isZeroingPropIvar(BinaryOperator *BOE) {
     if (BOE->getOpcode() == BO_Comma)
       return isZeroingPropIvar(BOE->getLHS()) &&
              isZeroingPropIvar(BOE->getRHS());
 
     if (BOE->getOpcode() != BO_Assign)
-        return false;
-
-    ASTContext &Ctx = Pass.Ctx;
+      return false;
 
     Expr *LHS = BOE->getLHS();
     if (ObjCIvarRefExpr *IV = dyn_cast<ObjCIvarRefExpr>(LHS)) {
@@ -172,25 +185,38 @@ private:
       if (!IvarBacksPropertySynthesis)
         return false;
     }
-    else if (ObjCPropertyRefExpr *PropRefExp = dyn_cast<ObjCPropertyRefExpr>(LHS)) {
-      // TODO: Using implicit property decl.
-      if (PropRefExp->isImplicitProperty())
-        return false;
-      if (ObjCPropertyDecl *PDecl = PropRefExp->getExplicitProperty()) {
-        if (!SynthesizedProperties.count(PDecl))
-          return false;
-      }
-    }
     else
         return false;
 
-    Expr *RHS = BOE->getRHS();
-    bool RHSIsNull = RHS->isNullPointerConstant(Ctx,
-                                                Expr::NPC_ValueDependentIsNull);
-    if (RHSIsNull)
+    return isZero(BOE->getRHS());
+  }
+
+  bool isZeroingPropIvar(PseudoObjectExpr *PO) {
+    BinaryOperator *BO = dyn_cast<BinaryOperator>(PO->getSyntacticForm());
+    if (!BO) return false;
+    if (BO->getOpcode() != BO_Assign) return false;
+
+    ObjCPropertyRefExpr *PropRefExp =
+      dyn_cast<ObjCPropertyRefExpr>(BO->getLHS()->IgnoreParens());
+    if (!PropRefExp) return false;
+
+    // TODO: Using implicit property decl.
+    if (PropRefExp->isImplicitProperty())
+      return false;
+
+    if (ObjCPropertyDecl *PDecl = PropRefExp->getExplicitProperty()) {
+      if (!SynthesizedProperties.count(PDecl))
+        return false;
+    }
+
+    return isZero(cast<OpaqueValueExpr>(BO->getRHS())->getSourceExpr());
+  }
+
+  bool isZero(Expr *E) {
+    if (E->isNullPointerConstant(Pass.Ctx, Expr::NPC_ValueDependentIsNull))
       return true;
 
-    return isZeroingPropIvar(RHS);
+    return isZeroingPropIvar(E);
   }
 };
 
diff --git a/lib/AST/DeclBase.cpp b/lib/AST/DeclBase.cpp
index a4daea2287..4c31bbd3d7 100644
--- a/lib/AST/DeclBase.cpp
+++ b/lib/AST/DeclBase.cpp
@@ -640,7 +640,11 @@ void Decl::CheckAccessDeclContext() const {
 }
 
 DeclContext *Decl::getNonClosureContext() {
-  DeclContext *DC = getDeclContext();
+  return getDeclContext()->getNonClosureAncestor();
+}
+
+DeclContext *DeclContext::getNonClosureAncestor() {
+  DeclContext *DC = this;
 
   // This is basically "while (DC->isClosure()) DC = DC->getParent();"
   // except that it's significantly more efficient to cast to a known
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index 3239973688..6eb6116b01 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -1694,6 +1694,19 @@ bool Expr::isUnusedResultAWarning(SourceLocation &Loc, SourceRange &R1,
     R1 = getSourceRange();
     return true;
 
+  case PseudoObjectExprClass: {
+    const PseudoObjectExpr *PO = cast<PseudoObjectExpr>(this);
+
+    // Only complain about things that have the form of a getter.
+    if (isa<UnaryOperator>(PO->getSyntacticForm()) ||
+        isa<BinaryOperator>(PO->getSyntacticForm()))
+      return false;
+
+    Loc = getExprLoc();
+    R1 = getSourceRange();
+    return true;
+  }
+
   case StmtExprClass: {
     // Statement exprs don't logically have side effects themselves, but are
     // sometimes used in macros in ways that give them a type that is unused.
@@ -2598,6 +2611,9 @@ Expr::isNullPointerConstant(ASTContext &Ctx,
   } else if (const MaterializeTemporaryExpr *M 
                                    = dyn_cast<MaterializeTemporaryExpr>(this)) {
     return M->GetTemporaryExpr()->isNullPointerConstant(Ctx, NPC);
+  } else if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(this)) {
+    if (const Expr *Source = OVE->getSourceExpr())
+      return Source->isNullPointerConstant(Ctx, NPC);
   }
 
   // C++0x nullptr_t is always a null pointer constant.
@@ -3306,6 +3322,72 @@ const OpaqueValueExpr *OpaqueValueExpr::findInCopyConstruct(const Expr *e) {
   return cast<OpaqueValueExpr>(e);
 }
 
+PseudoObjectExpr *PseudoObjectExpr::Create(ASTContext &Context, EmptyShell sh,
+                                           unsigned numSemanticExprs) {
+  void *buffer = Context.Allocate(sizeof(PseudoObjectExpr) +
+                                    (1 + numSemanticExprs) * sizeof(Expr*),
+                                  llvm::alignOf<PseudoObjectExpr>());
+  return new(buffer) PseudoObjectExpr(sh, numSemanticExprs);
+}
+
+PseudoObjectExpr::PseudoObjectExpr(EmptyShell shell, unsigned numSemanticExprs)
+  : Expr(PseudoObjectExprClass, shell) {
+  PseudoObjectExprBits.NumSubExprs = numSemanticExprs + 1;
+}
+
+PseudoObjectExpr *PseudoObjectExpr::Create(ASTContext &C, Expr *syntax,
+                                           ArrayRef<Expr*> semantics,
+                                           unsigned resultIndex) {
+  assert(syntax && "no syntactic expression!");
+  assert(semantics.size() && "no semantic expressions!");
+
+  QualType type;
+  ExprValueKind VK;
+  if (resultIndex == NoResult) {
+    type = C.VoidTy;
+    VK = VK_RValue;
+  } else {
+    assert(resultIndex < semantics.size());
+    type = semantics[resultIndex]->getType();
+    VK = semantics[resultIndex]->getValueKind();
+    assert(semantics[resultIndex]->getObjectKind() == OK_Ordinary);
+  }
+
+  void *buffer = C.Allocate(sizeof(PseudoObjectExpr) +
+                              (1 + semantics.size()) * sizeof(Expr*),
+                            llvm::alignOf<PseudoObjectExpr>());
+  return new(buffer) PseudoObjectExpr(type, VK, syntax, semantics,
+                                      resultIndex);
+}
+
+PseudoObjectExpr::PseudoObjectExpr(QualType type, ExprValueKind VK,
+                                   Expr *syntax, ArrayRef<Expr*> semantics,
+                                   unsigned resultIndex)
+  : Expr(PseudoObjectExprClass, type, VK, OK_Ordinary,
+         /*filled in at end of ctor*/ false, false, false, false) {
+  PseudoObjectExprBits.NumSubExprs = semantics.size() + 1;
+  PseudoObjectExprBits.ResultIndex = resultIndex + 1;
+
+  for (unsigned i = 0, e = semantics.size() + 1; i != e; ++i) {
+    Expr *E = (i == 0 ? syntax : semantics[i-1]);
+    getSubExprsBuffer()[i] = E;
+
+    if (E->isTypeDependent())
+      ExprBits.TypeDependent = true;
+    if (E->isValueDependent())
+      ExprBits.ValueDependent = true;
+    if (E->isInstantiationDependent())
+      ExprBits.InstantiationDependent = true;
+    if (E->containsUnexpandedParameterPack())
+      ExprBits.ContainsUnexpandedParameterPack = true;
+
+    if (isa<OpaqueValueExpr>(E))
+      assert(cast<OpaqueValueExpr>(E)->getSourceExpr() != 0 &&
+             "opaque-value semantic expressions for pseudo-object "
+             "operations must have sources");
+  }
+}
+
 //===----------------------------------------------------------------------===//
 //  ExprIterator.
 //===----------------------------------------------------------------------===//
diff --git a/lib/AST/ExprClassification.cpp b/lib/AST/ExprClassification.cpp
index 594ae69ec4..1251b96fba 100644
--- a/lib/AST/ExprClassification.cpp
+++ b/lib/AST/ExprClassification.cpp
@@ -232,6 +232,11 @@ static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E) {
     return ClassifyExprValueKind(Lang, E,
                                  cast<OpaqueValueExpr>(E)->getValueKind());
 
+    // Pseudo-object expressions can produce l-values with reference magic.
+  case Expr::PseudoObjectExprClass:
+    return ClassifyExprValueKind(Lang, E,
+                                 cast<PseudoObjectExpr>(E)->getValueKind());
+
     // Implicit casts are lvalues if they're lvalue casts. Other than that, we
     // only specifically record class temporaries.
   case Expr::ImplicitCastExprClass:
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index 3011b7f25f..9c9e473f7b 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -3450,6 +3450,7 @@ static ICEDiag CheckICE(const Expr* E, ASTContext &Ctx) {
   case Expr::AsTypeExprClass:
   case Expr::ObjCIndirectCopyRestoreExprClass:
   case Expr::MaterializeTemporaryExprClass:
+  case Expr::PseudoObjectExprClass:
   case Expr::AtomicExprClass:
     return ICEDiag(2, E->getLocStart());
 
diff --git a/lib/AST/ItaniumMangle.cpp b/lib/AST/ItaniumMangle.cpp
index 889cf513bb..b2e1d20ca0 100644
--- a/lib/AST/ItaniumMangle.cpp
+++ b/lib/AST/ItaniumMangle.cpp
@@ -2257,6 +2257,7 @@ recurse:
   case Expr::CXXNoexceptExprClass:
   case Expr::CUDAKernelCallExprClass:
   case Expr::AsTypeExprClass:
+  case Expr::PseudoObjectExprClass:
   case Expr::AtomicExprClass:
   {
     // As bad as this diagnostic is, it's better than crashing.
diff --git a/lib/AST/StmtDumper.cpp b/lib/AST/StmtDumper.cpp
index 54e62fe35b..2248343199 100644
--- a/lib/AST/StmtDumper.cpp
+++ b/lib/AST/StmtDumper.cpp
@@ -148,6 +148,7 @@ namespace  {
     void VisitCompoundAssignOperator(CompoundAssignOperator *Node);
     void VisitAddrLabelExpr(AddrLabelExpr *Node);
     void VisitBlockExpr(BlockExpr *Node);
+    void VisitOpaqueValueExpr(OpaqueValueExpr *Node);
 
     // C++
     void VisitCXXNamedCastExpr(CXXNamedCastExpr *Node);
@@ -524,6 +525,15 @@ void StmtDumper::VisitBlockExpr(BlockExpr *Node) {
   DumpSubTree(block->getBody());
 }
 
+void StmtDumper::VisitOpaqueValueExpr(OpaqueValueExpr *Node) {
+  DumpExpr(Node);
+
+  if (Expr *Source = Node->getSourceExpr()) {
+    OS << '\n';
+    DumpSubTree(Source);
+  }
+}
+
 // GNU extensions.
 
 void StmtDumper::VisitAddrLabelExpr(AddrLabelExpr *Node) {
diff --git a/lib/AST/StmtPrinter.cpp b/lib/AST/StmtPrinter.cpp
index 5b1654c924..04617bf9ac 100644
--- a/lib/AST/StmtPrinter.cpp
+++ b/lib/AST/StmtPrinter.cpp
@@ -1027,6 +1027,10 @@ void StmtPrinter::VisitVAArgExpr(VAArgExpr *Node) {
   OS << ")";
 }
 
+void StmtPrinter::VisitPseudoObjectExpr(PseudoObjectExpr *Node) {
+  PrintExpr(Node->getSyntacticForm());
+}
+
 void StmtPrinter::VisitAtomicExpr(AtomicExpr *Node) {
   const char *Name = 0;
   switch (Node->getOp()) {
diff --git a/lib/AST/StmtProfile.cpp b/lib/AST/StmtProfile.cpp
index db97e59804..5a6b771b9a 100644
--- a/lib/AST/StmtProfile.cpp
+++ b/lib/AST/StmtProfile.cpp
@@ -475,6 +475,15 @@ void StmtProfiler::VisitGenericSelectionExpr(const GenericSelectionExpr *S) {
   }
 }
 
+void StmtProfiler::VisitPseudoObjectExpr(const PseudoObjectExpr *S) {
+  VisitExpr(S);
+  for (PseudoObjectExpr::const_semantics_iterator
+         i = S->semantics_begin(), e = S->semantics_end(); i != e; ++i)
+    // Normally, we would not profile the source expressions of OVEs.
+    if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(*i))
+      Visit(OVE->getSourceExpr());
+}
+
 void StmtProfiler::VisitAtomicExpr(const AtomicExpr *S) {
   VisitExpr(S);
   ID.AddInteger(S->getOp());
diff --git a/lib/Analysis/CFG.cpp b/lib/Analysis/CFG.cpp
index 48888f672e..73879214f3 100644
--- a/lib/Analysis/CFG.cpp
+++ b/lib/Analysis/CFG.cpp
@@ -344,6 +344,7 @@ private:
   CFGBlock *VisitObjCAtTryStmt(ObjCAtTryStmt *S);
   CFGBlock *VisitObjCForCollectionStmt(ObjCForCollectionStmt *S);
   CFGBlock *VisitReturnStmt(ReturnStmt *R);
+  CFGBlock *VisitPseudoObjectExpr(PseudoObjectExpr *E);
   CFGBlock *VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *E,
                                           AddStmtChoice asc);
   CFGBlock *VisitStmtExpr(StmtExpr *S, AddStmtChoice asc);
@@ -981,6 +982,9 @@ CFGBlock *CFGBuilder::Visit(Stmt * S, AddStmtChoice asc) {
     case Stmt::OpaqueValueExprClass:
       return Block;
 
+    case Stmt::PseudoObjectExprClass:
+      return VisitPseudoObjectExpr(cast<PseudoObjectExpr>(S));
+
     case Stmt::ReturnStmtClass:
       return VisitReturnStmt(cast<ReturnStmt>(S));
 
@@ -1907,6 +1911,31 @@ CFGBlock *CFGBuilder::VisitObjCAtTryStmt(ObjCAtTryStmt *S) {
   return NYS();
 }
 
+CFGBlock *CFGBuilder::VisitPseudoObjectExpr(PseudoObjectExpr *E) {
+  autoCreateBlock();
+
+  // Add the PseudoObject as the last thing.
+  appendStmt(Block, E);
+
+  CFGBlock *lastBlock = Block;  
+
+  // Before that, evaluate all of the semantics in order.  In
+  // CFG-land, that means appending them in reverse order.
+  for (unsigned i = E->getNumSemanticExprs(); i != 0; ) {
+    Expr *Semantic = E->getSemanticExpr(--i);
+
+    // If the semantic is an opaque value, we're being asked to bind
+    // it to its source expression.
+    if (OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(Semantic))
+      Semantic = OVE->getSourceExpr();
+
+    if (CFGBlock *B = Visit(Semantic))
+      lastBlock = B;
+  }
+
+  return lastBlock;
+}
+
 CFGBlock *CFGBuilder::VisitWhileStmt(WhileStmt *W) {
   CFGBlock *LoopSuccessor = NULL;
 
diff --git a/lib/Analysis/LiveVariables.cpp b/lib/Analysis/LiveVariables.cpp
index cd6f09f2a7..f0dbc532b2 100644
--- a/lib/Analysis/LiveVariables.cpp
+++ b/lib/Analysis/LiveVariables.cpp
@@ -288,6 +288,18 @@ void TransferFunctions::Visit(Stmt *S) {
       }
       break;
     }
+    case Stmt::PseudoObjectExprClass: {
+      // A pseudo-object operation only directly consumes its result
+      // expression.
+      Expr *child = cast<PseudoObjectExpr>(S)->getResultExpr();
+      if (!child) return;
+      if (OpaqueValueExpr *OV = dyn_cast<OpaqueValueExpr>(child))
+        child = OV->getSourceExpr();
+      child = child->IgnoreParens();
+      val.liveStmts = LV.SSetFact.add(val.liveStmts, child);
+      return;
+    }
+
     // FIXME: These cases eventually shouldn't be needed.
     case Stmt::ExprWithCleanupsClass: {
       S = cast<ExprWithCleanups>(S)->getSubExpr();
diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index 9ad3ae8352..d7371141f3 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -672,6 +672,8 @@ LValue CodeGenFunction::EmitLValue(const Expr *E) {
     return EmitStringLiteralLValue(cast<StringLiteral>(E));
   case Expr::ObjCEncodeExprClass:
     return EmitObjCEncodeExprLValue(cast<ObjCEncodeExpr>(E));
+  case Expr::PseudoObjectExprClass:
+    return EmitPseudoObjectLValue(cast<PseudoObjectExpr>(E));
 
   case Expr::BlockDeclRefExprClass:
     return EmitBlockDeclRefLValue(cast<BlockDeclRefExpr>(E));
@@ -2768,3 +2770,86 @@ void CodeGenFunction::SetFPAccuracy(llvm::Value *Val, unsigned AccuracyN,
   cast<llvm::Instruction>(Val)->setMetadata(llvm::LLVMContext::MD_fpaccuracy,
                                             Node);
 }
+
+namespace {
+  struct LValueOrRValue {
+    LValue LV;
+    RValue RV;
+  };
+}
+
+static LValueOrRValue emitPseudoObjectExpr(CodeGenFunction &CGF,
+                                           const PseudoObjectExpr *E,
+                                           bool forLValue,
+                                           AggValueSlot slot) {
+  llvm::SmallVector<CodeGenFunction::OpaqueValueMappingData, 4> opaques;
+
+  // Find the result expression, if any.
+  const Expr *resultExpr = E->getResultExpr();
+  LValueOrRValue result;
+
+  for (PseudoObjectExpr::const_semantics_iterator
+         i = E->semantics_begin(), e = E->semantics_end(); i != e; ++i) {
+    const Expr *semantic = *i;
+
+    // If this semantic expression is an opaque value, bind it
+    // to the result of its source expression.
+    if (const OpaqueValueExpr *ov = dyn_cast<OpaqueValueExpr>(semantic)) {
+
+      // If this is the result expression, we may need to evaluate
+      // directly into the slot.
+      typedef CodeGenFunction::OpaqueValueMappingData OVMA;
+      OVMA opaqueData;
+      if (ov == resultExpr && ov->isRValue() && !forLValue &&
+          CodeGenFunction::hasAggregateLLVMType(ov->getType()) &&
+          !ov->getType()->isAnyComplexType()) {
+        CGF.EmitAggExpr(ov->getSourceExpr(), slot);
+
+        LValue LV = CGF.MakeAddrLValue(slot.getAddr(), ov->getType());
+        opaqueData = OVMA::bind(CGF, ov, LV);
+        result.RV = slot.asRValue();
+
+      // Otherwise, emit as normal.
+      } else {
+        opaqueData = OVMA::bind(CGF, ov, ov->getSourceExpr());
+
+        // If this is the result, also evaluate the result now.
+        if (ov == resultExpr) {
+          if (forLValue)
+            result.LV = CGF.EmitLValue(ov);
+          else
+            result.RV = CGF.EmitAnyExpr(ov, slot);
+        }
+      }
+
+      opaques.push_back(opaqueData);
+
+    // Otherwise, if the expression is the result, evaluate it
+    // and remember the result.
+    } else if (semantic == resultExpr) {
+      if (forLValue)
+        result.LV = CGF.EmitLValue(semantic);
+      else
+        result.RV = CGF.EmitAnyExpr(semantic, slot);
+
+    // Otherwise, evaluate the expression in an ignored context.
+    } else {
+      CGF.EmitIgnoredExpr(semantic);
+    }
+  }
+
+  // Unbind all the opaques now.
+  for (unsigned i = 0, e = opaques.size(); i != e; ++i)
+    opaques[i].unbind(CGF);
+
+  return result;
+}
+
+RValue CodeGenFunction::EmitPseudoObjectRValue(const PseudoObjectExpr *E,
+                                               AggValueSlot slot) {
+  return emitPseudoObjectExpr(*this, E, false, slot).RV;
+}
+
+LValue CodeGenFunction::EmitPseudoObjectLValue(const PseudoObjectExpr *E) {
+  return emitPseudoObjectExpr(*this, E, true, AggValueSlot::ignored()).LV;
+}
diff --git a/lib/CodeGen/CGExprAgg.cpp b/lib/CodeGen/CGExprAgg.cpp
index 0fa143391d..ffbc2e0732 100644
--- a/lib/CodeGen/CGExprAgg.cpp
+++ b/lib/CodeGen/CGExprAgg.cpp
@@ -148,6 +148,15 @@ public:
   void VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E);
   void VisitOpaqueValueExpr(OpaqueValueExpr *E);
 
+  void VisitPseudoObjectExpr(PseudoObjectExpr *E) {
+    if (E->isGLValue()) {
+      LValue LV = CGF.EmitPseudoObjectLValue(E);
+      return EmitFinalDestCopy(E, LV);
+    }
+
+    CGF.EmitPseudoObjectRValue(E, EnsureSlot(E->getType()));
+  }
+
   void VisitVAArgExpr(VAArgExpr *E);
 
   void EmitInitializationToLValue(Expr *E, LValue Address);
diff --git a/lib/CodeGen/CGExprComplex.cpp b/lib/CodeGen/CGExprComplex.cpp
index b6c416bc35..c09278c14e 100644
--- a/lib/CodeGen/CGExprComplex.cpp
+++ b/lib/CodeGen/CGExprComplex.cpp
@@ -137,6 +137,10 @@ public:
     return CGF.getOpaqueRValueMapping(E).getComplexVal();
   }
 
+  ComplexPairTy VisitPseudoObjectExpr(PseudoObjectExpr *E) {
+    return CGF.EmitPseudoObjectRValue(E).getComplexVal();
+  }
+
   // FIXME: CompoundLiteralExpr
 
   ComplexPairTy EmitCast(CastExpr::CastKind CK, Expr *Op, QualType DestTy);
diff --git a/lib/CodeGen/CGExprScalar.cpp b/lib/CodeGen/CGExprScalar.cpp
index 50c5057f3e..83ca159aa5 100644
--- a/lib/CodeGen/CGExprScalar.cpp
+++ b/lib/CodeGen/CGExprScalar.cpp
@@ -197,6 +197,10 @@ public:
     return llvm::ConstantInt::get(ConvertType(E->getType()),E->getPackLength());
   }
 
+  Value *VisitPseudoObjectExpr(PseudoObjectExpr *E) {
+    return CGF.EmitPseudoObjectRValue(E).getScalarVal();
+  }
+
   Value *VisitOpaqueValueExpr(OpaqueValueExpr *E) {
     if (E->isGLValue())
       return EmitLoadOfLValue(CGF.getOpaqueLValueMapping(E));
diff --git a/lib/CodeGen/CGObjC.cpp b/lib/CodeGen/CGObjC.cpp
index 0cd98ee319..f164103723 100644
--- a/lib/CodeGen/CGObjC.cpp
+++ b/lib/CodeGen/CGObjC.cpp
@@ -2231,6 +2231,59 @@ static bool shouldEmitSeparateBlockRetain(const Expr *e) {
   return true;
 }
 
+/// Try to emit a PseudoObjectExpr at +1.
+///
+/// This massively duplicates emitPseudoObjectRValue.
+static TryEmitResult tryEmitARCRetainPseudoObject(CodeGenFunction &CGF,
+                                                  const PseudoObjectExpr *E) {
+  llvm::SmallVector<CodeGenFunction::OpaqueValueMappingData, 4> opaques;
+
+  // Find the result expression.
+  const Expr *resultExpr = E->getResultExpr();
+  assert(resultExpr);
+  TryEmitResult result;
+
+  for (PseudoObjectExpr::const_semantics_iterator
+         i = E->semantics_begin(), e = E->semantics_end(); i != e; ++i) {
+    const Expr *semantic = *i;
+
+    // If this semantic expression is an opaque value, bind it
+    // to the result of its source expression.
+    if (const OpaqueValueExpr *ov = dyn_cast<OpaqueValueExpr>(semantic)) {
+      typedef CodeGenFunction::OpaqueValueMappingData OVMA;
+      OVMA opaqueData;
+
+      // If this semantic is the result of the pseudo-object
+      // expression, try to evaluate the source as +1.
+      if (ov == resultExpr) {
+        assert(!OVMA::shouldBindAsLValue(ov));
+        result = tryEmitARCRetainScalarExpr(CGF, ov->getSourceExpr());
+        opaqueData = OVMA::bind(CGF, ov, RValue::get(result.getPointer()));
+
+      // Otherwise, just bind it.
+      } else {
+        opaqueData = OVMA::bind(CGF, ov, ov->getSourceExpr());
+      }
+      opaques.push_back(opaqueData);
+
+    // Otherwise, if the expression is the result, evaluate it
+    // and remember the result.
+    } else if (semantic == resultExpr) {
+      result = tryEmitARCRetainScalarExpr(CGF, semantic);
+
+    // Otherwise, evaluate the expression in an ignored context.
+    } else {
+      CGF.EmitIgnoredExpr(semantic);
+    }
+  }
+
+  // Unbind all the opaques now.
+  for (unsigned i = 0, e = opaques.size(); i != e; ++i)
+    opaques[i].unbind(CGF);
+
+  return result;
+}
+
 static TryEmitResult
 tryEmitARCRetainScalarExpr(CodeGenFunction &CGF, const Expr *e) {
   // Look through cleanups.
@@ -2356,6 +2409,17 @@ tryEmitARCRetainScalarExpr(CodeGenFunction &CGF, const Expr *e) {
       llvm::Value *result = emitARCRetainCall(CGF, e);
       if (resultType) result = CGF.Builder.CreateBitCast(result, resultType);
       return TryEmitResult(result, true);
+
+    // Look through pseudo-object expressions.
+    } else if (const PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
+      TryEmitResult result
+        = tryEmitARCRetainPseudoObject(CGF, pseudo);
+      if (resultType) {
+        llvm::Value *value = result.getPointer();
+        value = CGF.Builder.CreateBitCast(value, resultType);
+        result.setPointer(value);
+      }
+      return result;
     }
 
     // Conservatively halt the search at any other expression kind.
diff --git a/lib/CodeGen/CGValue.h b/lib/CodeGen/CGValue.h
index 489e600b3d..bc94e8ebc9 100644
--- a/lib/CodeGen/CGValue.h
+++ b/lib/CodeGen/CGValue.h
@@ -27,6 +27,7 @@ namespace clang {
   class ObjCPropertyRefExpr;
 
 namespace CodeGen {
+  class AggValueSlot;
   class CGBitFieldInfo;
 
 /// RValue - This trivial value class