PR12086, PR15117

Introduce CXXStdInitializerListExpr node, representing the implicit
construction of a std::initializer_list<T> object from its underlying array.
The AST representation of such an expression goes from an InitListExpr with a
flag set, to a CXXStdInitializerListExpr containing a MaterializeTemporaryExpr
containing an InitListExpr (possibly wrapped in a CXXBindTemporaryExpr).

This more detailed representation has several advantages, the most important of
which is that the new MaterializeTemporaryExpr allows us to directly model
lifetime extension of the underlying temporary array. Using that, this patch
*drastically* simplifies the IR generation of this construct, provides IR
generation support for nested global initializer_list objects, fixes several
bugs where the destructors for the underlying array would accidentally not get
invoked, and provides constant expression evaluation support for
std::initializer_list objects.

llvm-svn: 183872

9 files changed, 95 insertions, 342 deletions

diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
index b3a14772ad0..9d08d1c7f7a 100644
--- a/clang/lib/CodeGen/CGClass.cpp
+++ b/clang/lib/CodeGen/CGClass.cpp
@@ -433,52 +433,45 @@ static void EmitAggMemberInitializer(CodeGenFunction &CGF,
                                      unsigned Index) {
   if (Index == ArrayIndexes.size()) {
     LValue LV = LHS;
-    { // Scope for Cleanups.
-      CodeGenFunction::RunCleanupsScope Cleanups(CGF);
-
-      if (ArrayIndexVar) {
-        // If we have an array index variable, load it and use it as an offset.
-        // Then, increment the value.
-        llvm::Value *Dest = LHS.getAddress();
-        llvm::Value *ArrayIndex = CGF.Builder.CreateLoad(ArrayIndexVar);
-        Dest = CGF.Builder.CreateInBoundsGEP(Dest, ArrayIndex, "destaddress");
-        llvm::Value *Next = llvm::ConstantInt::get(ArrayIndex->getType(), 1);
-        Next = CGF.Builder.CreateAdd(ArrayIndex, Next, "inc");
-        CGF.Builder.CreateStore(Next, ArrayIndexVar);    
-
-        // Update the LValue.
-        LV.setAddress(Dest);
-        CharUnits Align = CGF.getContext().getTypeAlignInChars(T);
-        LV.setAlignment(std::min(Align, LV.getAlignment()));
-      }
 
-      switch (CGF.getEvaluationKind(T)) {
-      case TEK_Scalar:
-        CGF.EmitScalarInit(Init, /*decl*/ 0, LV, false);
-        break;
-      case TEK_Complex:
-        CGF.EmitComplexExprIntoLValue(Init, LV, /*isInit*/ true);
-        break;
-      case TEK_Aggregate: {
-        AggValueSlot Slot =
-          AggValueSlot::forLValue(LV,
-                                  AggValueSlot::IsDestructed,
-                                  AggValueSlot::DoesNotNeedGCBarriers,
-                                  AggValueSlot::IsNotAliased);
-
-        CGF.EmitAggExpr(Init, Slot);
-        break;
-      }
-      }
+    if (ArrayIndexVar) {
+      // If we have an array index variable, load it and use it as an offset.
+      // Then, increment the value.
+      llvm::Value *Dest = LHS.getAddress();
+      llvm::Value *ArrayIndex = CGF.Builder.CreateLoad(ArrayIndexVar);
+      Dest = CGF.Builder.CreateInBoundsGEP(Dest, ArrayIndex, "destaddress");
+      llvm::Value *Next = llvm::ConstantInt::get(ArrayIndex->getType(), 1);
+      Next = CGF.Builder.CreateAdd(ArrayIndex, Next, "inc");
+      CGF.Builder.CreateStore(Next, ArrayIndexVar);
+
+      // Update the LValue.
+      LV.setAddress(Dest);
+      CharUnits Align = CGF.getContext().getTypeAlignInChars(T);
+      LV.setAlignment(std::min(Align, LV.getAlignment()));
     }
 
-    // Now, outside of the initializer cleanup scope, destroy the backing array
-    // for a std::initializer_list member.
-    CGF.MaybeEmitStdInitializerListCleanup(LV.getAddress(), Init);
+    switch (CGF.getEvaluationKind(T)) {
+    case TEK_Scalar:
+      CGF.EmitScalarInit(Init, /*decl*/ 0, LV, false);
+      break;
+    case TEK_Complex:
+      CGF.EmitComplexExprIntoLValue(Init, LV, /*isInit*/ true);
+      break;
+    case TEK_Aggregate: {
+      AggValueSlot Slot =
+        AggValueSlot::forLValue(LV,
+                                AggValueSlot::IsDestructed,
+                                AggValueSlot::DoesNotNeedGCBarriers,
+                                AggValueSlot::IsNotAliased);
+
+      CGF.EmitAggExpr(Init, Slot);
+      break;
+    }
+    }
 
     return;
   }
-  
+
   const ConstantArrayType *Array = CGF.getContext().getAsConstantArrayType(T);
   assert(Array && "Array initialization without the array type?");
   llvm::Value *IndexVar
@@ -512,16 +505,12 @@ static void EmitAggMemberInitializer(CodeGenFunction &CGF,
 
   CGF.EmitBlock(ForBody);
   llvm::BasicBlock *ContinueBlock = CGF.createBasicBlock("for.inc");
-  
-  {
-    CodeGenFunction::RunCleanupsScope Cleanups(CGF);
-    
-    // Inside the loop body recurse to emit the inner loop or, eventually, the
-    // constructor call.
-    EmitAggMemberInitializer(CGF, LHS, Init, ArrayIndexVar,
-                             Array->getElementType(), ArrayIndexes, Index + 1);
-  }
-  
+
+  // Inside the loop body recurse to emit the inner loop or, eventually, the
+  // constructor call.
+  EmitAggMemberInitializer(CGF, LHS, Init, ArrayIndexVar,
+                           Array->getElementType(), ArrayIndexes, Index + 1);
+
   CGF.EmitBlock(ContinueBlock);
 
   // Emit the increment of the loop counter.
@@ -726,7 +715,7 @@ void CodeGenFunction::EmitConstructorBody(FunctionArgList &Args) {
   if (IsTryBody)
     EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
 
-  EHScopeStack::stable_iterator CleanupDepth = EHStack.stable_begin();
+  RunCleanupsScope RunCleanups(*this);
 
   // TODO: in restricted cases, we can emit the vbase initializers of
   // a complete ctor and then delegate to the base ctor.
@@ -745,7 +734,7 @@ void CodeGenFunction::EmitConstructorBody(FunctionArgList &Args) {
   // initializers, which includes (along the exceptional path) the
   // destructors for those members and bases that were fully
   // constructed.
-  PopCleanupBlocks(CleanupDepth);
+  RunCleanups.ForceCleanup();
 
   if (IsTryBody)
     ExitCXXTryStmt(*cast<CXXTryStmt>(Body), true);
diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index 7fc79e08f0f..4d14014f9c9 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -1187,7 +1187,6 @@ void CodeGenFunction::EmitExprAsInit(const Expr *init,
                                          AggValueSlot::DoesNotNeedGCBarriers,
                                               AggValueSlot::IsNotAliased));
     }
-    MaybeEmitStdInitializerListCleanup(lvalue.getAddress(), init);
     return;
   }
   llvm_unreachable("bad evaluation kind");
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index d534ff440cf..f88da33fbf5 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -240,15 +240,6 @@ pushTemporaryCleanup(CodeGenFunction &CGF, const MaterializeTemporaryExpr *M,
     }
   }
 
-  if (const InitListExpr *ILE = dyn_cast<InitListExpr>(E)) {
-    if (ILE->initializesStdInitializerList()) {
-      // FIXME: This is wrong if the temporary has static or thread storage
-      // duration.
-      CGF.EmitStdInitializerListCleanup(ReferenceTemporary, ILE);
-      return;
-    }
-  }
-
   CXXDestructorDecl *ReferenceTemporaryDtor = 0;
   if (const RecordType *RT =
           E->getType()->getBaseElementTypeUnsafe()->getAs<RecordType>()) {
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index f8b19d686b2..f3eb34567bd 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -91,7 +91,6 @@ public:
 
   void EmitMoveFromReturnSlot(const Expr *E, RValue Src);
 
-  void EmitStdInitializerList(llvm::Value *DestPtr, InitListExpr *InitList);
   void EmitArrayInit(llvm::Value *DestPtr, llvm::ArrayType *AType,
                      QualType elementType, InitListExpr *E);
 
@@ -177,6 +176,7 @@ public:
   void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
   void VisitCXXConstructExpr(const CXXConstructExpr *E);
   void VisitLambdaExpr(LambdaExpr *E);
+  void VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E);
   void VisitExprWithCleanups(ExprWithCleanups *E);
   void VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E);
   void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); }
@@ -345,89 +345,70 @@ void AggExprEmitter::EmitCopy(QualType type, const AggValueSlot &dest,
                         std::min(dest.getAlignment(), src.getAlignment()));
 }
 
-static QualType GetStdInitializerListElementType(QualType T) {
-  // Just assume that this is really std::initializer_list.
-  ClassTemplateSpecializationDecl *specialization =
-      cast<ClassTemplateSpecializationDecl>(T->castAs<RecordType>()->getDecl());
-  return specialization->getTemplateArgs()[0].getAsType();
-}
-
-/// \brief Prepare cleanup for the temporary array.
-static void EmitStdInitializerListCleanup(CodeGenFunction &CGF,
-                                          QualType arrayType,
-                                          llvm::Value *addr,
-                                          const InitListExpr *initList) {
-  QualType::DestructionKind dtorKind = arrayType.isDestructedType();
-  if (!dtorKind)
-    return; // Type doesn't need destroying.
-  if (dtorKind != QualType::DK_cxx_destructor) {
-    CGF.ErrorUnsupported(initList, "ObjC ARC type in initializer_list");
-    return;
-  }
-
-  CodeGenFunction::Destroyer *destroyer = CGF.getDestroyer(dtorKind);
-  CGF.pushDestroy(NormalAndEHCleanup, addr, arrayType, destroyer,
-                  /*EHCleanup=*/true);
-}
-
 /// \brief Emit the initializer for a std::initializer_list initialized with a
 /// real initializer list.
-void AggExprEmitter::EmitStdInitializerList(llvm::Value *destPtr,
-                                            InitListExpr *initList) {
-  // We emit an array containing the elements, then have the init list point
-  // at the array.
-  ASTContext &ctx = CGF.getContext();
-  unsigned numInits = initList->getNumInits();
-  QualType element = GetStdInitializerListElementType(initList->getType());
-  llvm::APInt size(ctx.getTypeSize(ctx.getSizeType()), numInits);
-  QualType array = ctx.getConstantArrayType(element, size, ArrayType::Normal,0);
-  llvm::Type *LTy = CGF.ConvertTypeForMem(array);
-  llvm::AllocaInst *alloc = CGF.CreateTempAlloca(LTy);
-  alloc->setAlignment(ctx.getTypeAlignInChars(array).getQuantity());
-  alloc->setName(".initlist.");
-
-  EmitArrayInit(alloc, cast<llvm::ArrayType>(LTy), element, initList);
-
-  // FIXME: The diagnostics are somewhat out of place here.
-  RecordDecl *record = initList->getType()->castAs<RecordType>()->getDecl();
-  RecordDecl::field_iterator field = record->field_begin();
-  if (field == record->field_end()) {
-    CGF.ErrorUnsupported(initList, "weird std::initializer_list");
+void
+AggExprEmitter::VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E) {
+  // Emit an array containing the elements.  The array is externally destructed
+  // if the std::initializer_list object is.
+  ASTContext &Ctx = CGF.getContext();
+  LValue Array = CGF.EmitLValue(E->getSubExpr());
+  assert(Array.isSimple() && "initializer_list array not a simple lvalue");
+  llvm::Value *ArrayPtr = Array.getAddress();
+
+  const ConstantArrayType *ArrayType =
+      Ctx.getAsConstantArrayType(E->getSubExpr()->getType());
+  assert(ArrayType && "std::initializer_list constructed from non-array");
+
+  // FIXME: Perform the checks on the field types in SemaInit.
+  RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl();
+  RecordDecl::field_iterator Field = Record->field_begin();
+  if (Field == Record->field_end()) {
+    CGF.ErrorUnsupported(E, "weird std::initializer_list");
     return;
   }
 
-  QualType elementPtr = ctx.getPointerType(element.withConst());
-
   // Start pointer.
-  if (!ctx.hasSameType(field->getType(), elementPtr)) {
-    CGF.ErrorUnsupported(initList, "weird std::initializer_list");
+  if (!Field->getType()->isPointerType() ||
+      !Ctx.hasSameType(Field->getType()->getPointeeType(),
+                       ArrayType->getElementType())) {
+    CGF.ErrorUnsupported(E, "weird std::initializer_list");
     return;
   }
-  LValue DestLV = CGF.MakeNaturalAlignAddrLValue(destPtr, initList->getType());
-  LValue start = CGF.EmitLValueForFieldInitialization(DestLV, *field);
-  llvm::Value *arrayStart = Builder.CreateStructGEP(alloc, 0, "arraystart");
-  CGF.EmitStoreThroughLValue(RValue::get(arrayStart), start);
-  ++field;
-
-  if (field == record->field_end()) {
-    CGF.ErrorUnsupported(initList, "weird std::initializer_list");
+
+  AggValueSlot Dest = EnsureSlot(E->getType());
+  LValue DestLV = CGF.MakeAddrLValue(Dest.getAddr(), E->getType(),
+                                     Dest.getAlignment());
+  LValue Start = CGF.EmitLValueForFieldInitialization(DestLV, *Field);
+  llvm::Value *Zero = llvm::ConstantInt::get(CGF.PtrDiffTy, 0);
+  llvm::Value *IdxStart[] = { Zero, Zero };
+  llvm::Value *ArrayStart =
+      Builder.CreateInBoundsGEP(ArrayPtr, IdxStart, "arraystart");
+  CGF.EmitStoreThroughLValue(RValue::get(ArrayStart), Start);
+  ++Field;
+
+  if (Field == Record->field_end()) {
+    CGF.ErrorUnsupported(E, "weird std::initializer_list");
     return;
   }
-  LValue endOrLength = CGF.EmitLValueForFieldInitialization(DestLV, *field);
-  if (ctx.hasSameType(field->getType(), elementPtr)) {
+
+  llvm::Value *Size = Builder.getInt(ArrayType->getSize());
+  LValue EndOrLength = CGF.EmitLValueForFieldInitialization(DestLV, *Field);
+  if (Field->getType()->isPointerType() &&
+      Ctx.hasSameType(Field->getType()->getPointeeType(),
+                      ArrayType->getElementType())) {
     // End pointer.
-    llvm::Value *arrayEnd = Builder.CreateStructGEP(alloc,numInits, "arrayend");
-    CGF.EmitStoreThroughLValue(RValue::get(arrayEnd), endOrLength);
-  } else if(ctx.hasSameType(field->getType(), ctx.getSizeType())) {
+    llvm::Value *IdxEnd[] = { Zero, Size };
+    llvm::Value *ArrayEnd =
+        Builder.CreateInBoundsGEP(ArrayPtr, IdxEnd, "arrayend");
+    CGF.EmitStoreThroughLValue(RValue::get(ArrayEnd), EndOrLength);
+  } else if (Ctx.hasSameType(Field->getType(), Ctx.getSizeType())) {
     // Length.
-    CGF.EmitStoreThroughLValue(RValue::get(Builder.getInt(size)), endOrLength);
+    CGF.EmitStoreThroughLValue(RValue::get(Size), EndOrLength);
   } else {
-    CGF.ErrorUnsupported(initList, "weird std::initializer_list");
+    CGF.ErrorUnsupported(E, "weird std::initializer_list");
     return;
   }
-
-  if (!Dest.isExternallyDestructed())
-    EmitStdInitializerListCleanup(CGF, array, alloc, initList);
 }
 
 /// \brief Emit initialization of an array from an initializer list.
@@ -490,15 +471,8 @@ void AggExprEmitter::EmitArrayInit(llvm::Value *DestPtr, llvm::ArrayType *AType,
       if (endOfInit) Builder.CreateStore(element, endOfInit);
     }
 
-    // If these are nested std::initializer_list inits, do them directly,
-    // because they are conceptually the same "location".
-    InitListExpr *initList = dyn_cast<InitListExpr>(E->getInit(i));
-    if (initList && initList->initializesStdInitializerList()) {
-      EmitStdInitializerList(element, initList);
-    } else {
-      LValue elementLV = CGF.MakeAddrLValue(element, elementType);
-      EmitInitializationToLValue(E->getInit(i), elementLV);
-    }
+    LValue elementLV = CGF.MakeAddrLValue(element, elementType);
+    EmitInitializationToLValue(E->getInit(i), elementLV);
   }
 
   // Check whether there's a non-trivial array-fill expression.
@@ -1161,11 +1135,6 @@ void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
 
   AggValueSlot Dest = EnsureSlot(E->getType());
 
-  if (E->initializesStdInitializerList()) {
-    EmitStdInitializerList(Dest.getAddr(), E);
-    return;
-  }
-
   LValue DestLV = CGF.MakeAddrLValue(Dest.getAddr(), E->getType(),
                                      Dest.getAlignment());
 
@@ -1546,58 +1515,3 @@ void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr,
                        alignment.getQuantity(), isVolatile,
                        /*TBAATag=*/0, TBAAStructTag);
 }
-
-void CodeGenFunction::MaybeEmitStdInitializerListCleanup(llvm::Value *loc,
-                                                         const Expr *init) {
-  const ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(init);
-  if (cleanups)
-    init = cleanups->getSubExpr();
-
-  if (isa<InitListExpr>(init) &&
-      cast<InitListExpr>(init)->initializesStdInitializerList()) {
-    // We initialized this std::initializer_list with an initializer list.
-    // A backing array was created. Push a cleanup for it.
-    EmitStdInitializerListCleanup(loc, cast<InitListExpr>(init));
-  }
-}
-
-static void EmitRecursiveStdInitializerListCleanup(CodeGenFunction &CGF,
-                                                   llvm::Value *arrayStart,
-                                                   const InitListExpr *init) {
-  // Check if there are any recursive cleanups to do, i.e. if we have
-  //   std::initializer_list<std::initializer_list<obj>> list = {{obj()}};
-  // then we need to destroy the inner array as well.
-  for (unsigned i = 0, e = init->getNumInits(); i != e; ++i) {
-    const InitListExpr *subInit = dyn_cast<InitListExpr>(init->getInit(i));
-    if (!subInit || !subInit->initializesStdInitializerList())
-      continue;
-
-    // This one needs to be destroyed. Get the address of the std::init_list.
-    llvm::Value *offset = llvm::ConstantInt::get(CGF.SizeTy, i);
-    llvm::Value *loc = CGF.Builder.CreateInBoundsGEP(arrayStart, offset,
-                                                 "std.initlist");
-    CGF.EmitStdInitializerListCleanup(loc, subInit);
-  }
-}
-
-void CodeGenFunction::EmitStdInitializerListCleanup(llvm::Value *loc,
-                                                    const InitListExpr *init) {
-  ASTContext &ctx = getContext();
-  QualType element = GetStdInitializerListElementType(init->getType());
-  unsigned numInits = init->getNumInits();
-  llvm::APInt size(ctx.getTypeSize(ctx.getSizeType()), numInits);
-  QualType array =ctx.getConstantArrayType(element, size, ArrayType::Normal, 0);
-  QualType arrayPtr = ctx.getPointerType(array);
-  llvm::Type *arrayPtrType = ConvertType(arrayPtr);
-
-  // lvalue is the location of a std::initializer_list, which as its first
-  // element has a pointer to the array we want to destroy.
-  llvm::Value *startPointer = Builder.CreateStructGEP(loc, 0, "startPointer");
-  llvm::Value *startAddress = Builder.CreateLoad(startPointer, "startAddress");
-
-  ::EmitRecursiveStdInitializerListCleanup(*this, startAddress, init);
-
-  llvm::Value *arrayAddress =
-      Builder.CreateBitCast(startAddress, arrayPtrType, "arrayAddress");
-  ::EmitStdInitializerListCleanup(*this, array, arrayAddress, init);
-}
diff --git a/clang/lib/CodeGen/CGExprCXX.cpp b/clang/lib/CodeGen/CGExprCXX.cpp
index 83c8ace98cd..60a70f8e07f 100644
--- a/clang/lib/CodeGen/CGExprCXX.cpp
+++ b/clang/lib/CodeGen/CGExprCXX.cpp
@@ -838,8 +838,6 @@ static void StoreAnyExprIntoOneUnit(CodeGenFunction &CGF, const Expr *Init,
                               AggValueSlot::DoesNotNeedGCBarriers,
                               AggValueSlot::IsNotAliased);
     CGF.EmitAggExpr(Init, Slot);
-
-    CGF.MaybeEmitStdInitializerListCleanup(NewPtr, Init);
     return;
   }
   }
diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp
index ca331cc92be..3e13e972801 100644
--- a/clang/lib/CodeGen/CGExprConstant.cpp
+++ b/clang/lib/CodeGen/CGExprConstant.cpp
@@ -368,11 +368,6 @@ void ConstStructBuilder::ConvertStructToPacked() {
 }
                             
 bool ConstStructBuilder::Build(InitListExpr *ILE) {
-  if (ILE->initializesStdInitializerList()) {
-    //CGM.ErrorUnsupported(ILE, "global std::initializer_list");
-    return false;
-  }
-
   RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl();
   const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
 
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 7bbf788eb52..4619322e1e1 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -1631,10 +1631,6 @@ public:
   llvm::Value *EmitDynamicCast(llvm::Value *V, const CXXDynamicCastExpr *DCE);
   llvm::Value* EmitCXXUuidofExpr(const CXXUuidofExpr *E);
 
-  void MaybeEmitStdInitializerListCleanup(llvm::Value *loc, const Expr *init);
-  void EmitStdInitializerListCleanup(llvm::Value *loc,
-                                     const InitListExpr *init);
-
   /// \brief Situations in which we might emit a check for the suitability of a
   ///        pointer or glvalue.
   enum TypeCheckKind {
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index d49fc0b0315..f6218cddfb5 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1628,125 +1628,6 @@ CharUnits CodeGenModule::GetTargetTypeStoreSize(llvm::Type *Ty) const {
       TheDataLayout.getTypeStoreSizeInBits(Ty));
 }
 
-llvm::Constant *
-CodeGenModule::MaybeEmitGlobalStdInitializerListInitializer(const VarDecl *D,
-                                                       const Expr *rawInit) {
-  ArrayRef<ExprWithCleanups::CleanupObject> cleanups;
-  if (const ExprWithCleanups *withCleanups =
-          dyn_cast<ExprWithCleanups>(rawInit)) {
-    cleanups = withCleanups->getObjects();
-    rawInit = withCleanups->getSubExpr();
-  }
-
-  const InitListExpr *init = dyn_cast<InitListExpr>(rawInit);
-  if (!init || !init->initializesStdInitializerList() ||
-      init->getNumInits() == 0)
-    return 0;
-
-  ASTContext &ctx = getContext();
-  unsigned numInits = init->getNumInits();
-  // FIXME: This check is here because we would otherwise silently miscompile
-  // nested global std::initializer_lists. Better would be to have a real
-  // implementation.
-  for (unsigned i = 0; i < numInits; ++i) {
-    const InitListExpr *inner = dyn_cast<InitListExpr>(init->getInit(i));
-    if (inner && inner->initializesStdInitializerList()) {
-      ErrorUnsupported(inner, "nested global std::initializer_list");
-      return 0;
-    }
-  }
-
-  // Synthesize a fake VarDecl for the array and initialize that.
-  QualType elementType = init->getInit(0)->getType();
-  llvm::APInt numElements(ctx.getTypeSize(ctx.getSizeType()), numInits);
-  QualType arrayType = ctx.getConstantArrayType(elementType, numElements,
-                                                ArrayType::Normal, 0);
-
-  IdentifierInfo *name = &ctx.Idents.get(D->getNameAsString() + "__initlist");
-  TypeSourceInfo *sourceInfo = ctx.getTrivialTypeSourceInfo(
-                                              arrayType, D->getLocation());
-  VarDecl *backingArray = VarDecl::Create(ctx, const_cast<DeclContext*>(
-                                                          D->getDeclContext()),
-                                          D->getLocStart(), D->getLocation(),
-                                          name, arrayType, sourceInfo,
-                                          SC_Static);
-  backingArray->setTSCSpec(D->getTSCSpec());
-
-  // Now clone the InitListExpr to initialize the array instead.
-  // Incredible hack: we want to use the existing InitListExpr here, so we need
-  // to tell it that it no longer initializes a std::initializer_list.
-  ArrayRef<Expr*> Inits(const_cast<InitListExpr*>(init)->getInits(),
-                        init->getNumInits());
-  Expr *arrayInit = new (ctx) InitListExpr(ctx, init->getLBraceLoc(), Inits,
-                                           init->getRBraceLoc());
-  arrayInit->setType(arrayType);
-
-  if (!cleanups.empty())
-    arrayInit = ExprWithCleanups::Create(ctx, arrayInit, cleanups);
-
-  backingArray->setInit(arrayInit);
-
-  // Emit the definition of the array.
-  EmitGlobalVarDefinition(backingArray);
-
-  // Inspect the initializer list to validate it and determine its type.
-  // FIXME: doing this every time is probably inefficient; caching would be nice
-  RecordDecl *record = init->getType()->castAs<RecordType>()->getDecl();
-  RecordDecl::field_iterator field = record->field_begin();
-  if (field == record->field_end()) {
-    ErrorUnsupported(D, "weird std::initializer_list");
-    return 0;
-  }
-  QualType elementPtr = ctx.getPointerType(elementType.withConst());
-  // Start pointer.
-  if (!ctx.hasSameType(field->getType(), elementPtr)) {
-    ErrorUnsupported(D, "weird std::initializer_list");
-    return 0;
-  }
-  ++field;
-  if (field == record->field_end()) {
-    ErrorUnsupported(D, "weird std::initializer_list");
-    return 0;
-  }
-  bool isStartEnd = false;
-  if (ctx.hasSameType(field->getType(), elementPtr)) {
-    // End pointer.
-    isStartEnd = true;
-  } else if(!ctx.hasSameType(field->getType(), ctx.getSizeType())) {
-    ErrorUnsupported(D, "weird std::initializer_list");
-    return 0;
-  }
-
-  // Now build an APValue representing the std::initializer_list.
-  APValue initListValue(APValue::UninitStruct(), 0, 2);
-  APValue &startField = initListValue.getStructField(0);
-  APValue::LValuePathEntry startOffsetPathEntry;
-  startOffsetPathEntry.ArrayIndex = 0;
-  startField = APValue(APValue::LValueBase(backingArray),
-                       CharUnits::fromQuantity(0),
-                       llvm::makeArrayRef(startOffsetPathEntry),
-                       /*IsOnePastTheEnd=*/false, 0);
-
-  if (isStartEnd) {
-    APValue &endField = initListValue.getStructField(1);
-    APValue::LValuePathEntry endOffsetPathEntry;
-    endOffsetPathEntry.ArrayIndex = numInits;
-    endField = APValue(APValue::LValueBase(backingArray),
-                       ctx.getTypeSizeInChars(elementType) * numInits,
-                       llvm::makeArrayRef(endOffsetPathEntry),
-                       /*IsOnePastTheEnd=*/true, 0);
-  } else {
-    APValue &sizeField = initListValue.getStructField(1);
-    sizeField = APValue(llvm::APSInt(numElements));
-  }
-
-  // Emit the constant for the initializer_list.
-  llvm::Constant *llvmInit =
-      EmitConstantValueForMemory(initListValue, D->getType());
-  assert(llvmInit && "failed to initialize as constant");
-  return llvmInit;
-}
-
 unsigned CodeGenModule::GetGlobalVarAddressSpace(const VarDecl *D,
                                                  unsigned AddrSpace) {
   if (LangOpts.CUDA && CodeGenOpts.CUDAIsDevice) {
@@ -1817,18 +1698,10 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
     assert(!ASTTy->isIncompleteType() && "Unexpected incomplete type");
     Init = EmitNullConstant(D->getType());
   } else {
-    // If this is a std::initializer_list, emit the special initializer.
-    Init = MaybeEmitGlobalStdInitializerListInitializer(D, InitExpr);
-    // An empty init list will perform zero-initialization, which happens
-    // to be exactly what we want.
-    // FIXME: It does so in a global constructor, which is *not* what we
-    // want.
+    initializedGlobalDecl = GlobalDecl(D);
+    Init = EmitConstantInit(*InitDecl);
 
     if (!Init) {
-      initializedGlobalDecl = GlobalDecl(D);
-      Init = EmitConstantInit(*InitDecl);
-    }
-    if (!Init) {
       QualType T = InitExpr->getType();
       if (D->getType()->isReferenceType())
         T = D->getType();
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index b2ff60deff2..ffb1243726e 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -1020,8 +1020,6 @@ private:
 
   void EmitGlobalFunctionDefinition(GlobalDecl GD);
   void EmitGlobalVarDefinition(const VarDecl *D);
-  llvm::Constant *MaybeEmitGlobalStdInitializerListInitializer(const VarDecl *D,
-                                                              const Expr *init);
   void EmitAliasDefinition(GlobalDecl GD);
   void EmitObjCPropertyImplementations(const ObjCImplementationDecl *D);
   void EmitObjCIvarInitializations(ObjCImplementationDecl *D);