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      1 //===---- CGBuiltin.cpp - Emit LLVM Code for builtins ---------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This contains code to emit Objective-C code as LLVM code.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "CGDebugInfo.h"
     15 #include "CGObjCRuntime.h"
     16 #include "CodeGenFunction.h"
     17 #include "CodeGenModule.h"
     18 #include "TargetInfo.h"
     19 #include "clang/AST/ASTContext.h"
     20 #include "clang/AST/DeclObjC.h"
     21 #include "clang/AST/StmtObjC.h"
     22 #include "clang/Basic/Diagnostic.h"
     23 #include "clang/CodeGen/CGFunctionInfo.h"
     24 #include "llvm/ADT/STLExtras.h"
     25 #include "llvm/IR/CallSite.h"
     26 #include "llvm/IR/DataLayout.h"
     27 #include "llvm/IR/InlineAsm.h"
     28 using namespace clang;
     29 using namespace CodeGen;
     30 
     31 typedef llvm::PointerIntPair<llvm::Value*,1,bool> TryEmitResult;
     32 static TryEmitResult
     33 tryEmitARCRetainScalarExpr(CodeGenFunction &CGF, const Expr *e);
     34 static RValue AdjustRelatedResultType(CodeGenFunction &CGF,
     35                                       QualType ET,
     36                                       const ObjCMethodDecl *Method,
     37                                       RValue Result);
     38 
     39 /// Given the address of a variable of pointer type, find the correct
     40 /// null to store into it.
     41 static llvm::Constant *getNullForVariable(llvm::Value *addr) {
     42   llvm::Type *type =
     43     cast<llvm::PointerType>(addr->getType())->getElementType();
     44   return llvm::ConstantPointerNull::get(cast<llvm::PointerType>(type));
     45 }
     46 
     47 /// Emits an instance of NSConstantString representing the object.
     48 llvm::Value *CodeGenFunction::EmitObjCStringLiteral(const ObjCStringLiteral *E)
     49 {
     50   llvm::Constant *C =
     51       CGM.getObjCRuntime().GenerateConstantString(E->getString());
     52   // FIXME: This bitcast should just be made an invariant on the Runtime.
     53   return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType()));
     54 }
     55 
     56 /// EmitObjCBoxedExpr - This routine generates code to call
     57 /// the appropriate expression boxing method. This will either be
     58 /// one of +[NSNumber numberWith<Type>:], or +[NSString stringWithUTF8String:].
     59 ///
     60 llvm::Value *
     61 CodeGenFunction::EmitObjCBoxedExpr(const ObjCBoxedExpr *E) {
     62   // Generate the correct selector for this literal's concrete type.
     63   // Get the method.
     64   const ObjCMethodDecl *BoxingMethod = E->getBoxingMethod();
     65   assert(BoxingMethod && "BoxingMethod is null");
     66   assert(BoxingMethod->isClassMethod() && "BoxingMethod must be a class method");
     67   Selector Sel = BoxingMethod->getSelector();
     68 
     69   // Generate a reference to the class pointer, which will be the receiver.
     70   // Assumes that the method was introduced in the class that should be
     71   // messaged (avoids pulling it out of the result type).
     72   CGObjCRuntime &Runtime = CGM.getObjCRuntime();
     73   const ObjCInterfaceDecl *ClassDecl = BoxingMethod->getClassInterface();
     74   llvm::Value *Receiver = Runtime.GetClass(*this, ClassDecl);
     75 
     76   CallArgList Args;
     77   EmitCallArgs(Args, BoxingMethod, E->arg_begin(), E->arg_end());
     78 
     79   RValue result = Runtime.GenerateMessageSend(
     80       *this, ReturnValueSlot(), BoxingMethod->getReturnType(), Sel, Receiver,
     81       Args, ClassDecl, BoxingMethod);
     82   return Builder.CreateBitCast(result.getScalarVal(),
     83                                ConvertType(E->getType()));
     84 }
     85 
     86 llvm::Value *CodeGenFunction::EmitObjCCollectionLiteral(const Expr *E,
     87                                     const ObjCMethodDecl *MethodWithObjects) {
     88   ASTContext &Context = CGM.getContext();
     89   const ObjCDictionaryLiteral *DLE = nullptr;
     90   const ObjCArrayLiteral *ALE = dyn_cast<ObjCArrayLiteral>(E);
     91   if (!ALE)
     92     DLE = cast<ObjCDictionaryLiteral>(E);
     93 
     94   // Compute the type of the array we're initializing.
     95   uint64_t NumElements =
     96     ALE ? ALE->getNumElements() : DLE->getNumElements();
     97   llvm::APInt APNumElements(Context.getTypeSize(Context.getSizeType()),
     98                             NumElements);
     99   QualType ElementType = Context.getObjCIdType().withConst();
    100   QualType ElementArrayType
    101     = Context.getConstantArrayType(ElementType, APNumElements,
    102                                    ArrayType::Normal, /*IndexTypeQuals=*/0);
    103 
    104   // Allocate the temporary array(s).
    105   llvm::AllocaInst *Objects = CreateMemTemp(ElementArrayType, "objects");
    106   llvm::AllocaInst *Keys = nullptr;
    107   if (DLE)
    108     Keys = CreateMemTemp(ElementArrayType, "keys");
    109 
    110   // In ARC, we may need to do extra work to keep all the keys and
    111   // values alive until after the call.
    112   SmallVector<llvm::Value *, 16> NeededObjects;
    113   bool TrackNeededObjects =
    114     (getLangOpts().ObjCAutoRefCount &&
    115     CGM.getCodeGenOpts().OptimizationLevel != 0);
    116 
    117   // Perform the actual initialialization of the array(s).
    118   for (uint64_t i = 0; i < NumElements; i++) {
    119     if (ALE) {
    120       // Emit the element and store it to the appropriate array slot.
    121       const Expr *Rhs = ALE->getElement(i);
    122       LValue LV = LValue::MakeAddr(
    123           Builder.CreateStructGEP(Objects->getAllocatedType(), Objects, i),
    124           ElementType, Context.getTypeAlignInChars(Rhs->getType()), Context);
    125 
    126       llvm::Value *value = EmitScalarExpr(Rhs);
    127       EmitStoreThroughLValue(RValue::get(value), LV, true);
    128       if (TrackNeededObjects) {
    129         NeededObjects.push_back(value);
    130       }
    131     } else {
    132       // Emit the key and store it to the appropriate array slot.
    133       const Expr *Key = DLE->getKeyValueElement(i).Key;
    134       LValue KeyLV = LValue::MakeAddr(
    135           Builder.CreateStructGEP(Keys->getAllocatedType(), Keys, i),
    136           ElementType, Context.getTypeAlignInChars(Key->getType()), Context);
    137       llvm::Value *keyValue = EmitScalarExpr(Key);
    138       EmitStoreThroughLValue(RValue::get(keyValue), KeyLV, /*isInit=*/true);
    139 
    140       // Emit the value and store it to the appropriate array slot.
    141       const Expr *Value = DLE->getKeyValueElement(i).Value;
    142       LValue ValueLV = LValue::MakeAddr(
    143           Builder.CreateStructGEP(Objects->getAllocatedType(), Objects, i),
    144           ElementType, Context.getTypeAlignInChars(Value->getType()), Context);
    145       llvm::Value *valueValue = EmitScalarExpr(Value);
    146       EmitStoreThroughLValue(RValue::get(valueValue), ValueLV, /*isInit=*/true);
    147       if (TrackNeededObjects) {
    148         NeededObjects.push_back(keyValue);
    149         NeededObjects.push_back(valueValue);
    150       }
    151     }
    152   }
    153 
    154   // Generate the argument list.
    155   CallArgList Args;
    156   ObjCMethodDecl::param_const_iterator PI = MethodWithObjects->param_begin();
    157   const ParmVarDecl *argDecl = *PI++;
    158   QualType ArgQT = argDecl->getType().getUnqualifiedType();
    159   Args.add(RValue::get(Objects), ArgQT);
    160   if (DLE) {
    161     argDecl = *PI++;
    162     ArgQT = argDecl->getType().getUnqualifiedType();
    163     Args.add(RValue::get(Keys), ArgQT);
    164   }
    165   argDecl = *PI;
    166   ArgQT = argDecl->getType().getUnqualifiedType();
    167   llvm::Value *Count =
    168     llvm::ConstantInt::get(CGM.getTypes().ConvertType(ArgQT), NumElements);
    169   Args.add(RValue::get(Count), ArgQT);
    170 
    171   // Generate a reference to the class pointer, which will be the receiver.
    172   Selector Sel = MethodWithObjects->getSelector();
    173   QualType ResultType = E->getType();
    174   const ObjCObjectPointerType *InterfacePointerType
    175     = ResultType->getAsObjCInterfacePointerType();
    176   ObjCInterfaceDecl *Class
    177     = InterfacePointerType->getObjectType()->getInterface();
    178   CGObjCRuntime &Runtime = CGM.getObjCRuntime();
    179   llvm::Value *Receiver = Runtime.GetClass(*this, Class);
    180 
    181   // Generate the message send.
    182   RValue result = Runtime.GenerateMessageSend(
    183       *this, ReturnValueSlot(), MethodWithObjects->getReturnType(), Sel,
    184       Receiver, Args, Class, MethodWithObjects);
    185 
    186   // The above message send needs these objects, but in ARC they are
    187   // passed in a buffer that is essentially __unsafe_unretained.
    188   // Therefore we must prevent the optimizer from releasing them until
    189   // after the call.
    190   if (TrackNeededObjects) {
    191     EmitARCIntrinsicUse(NeededObjects);
    192   }
    193 
    194   return Builder.CreateBitCast(result.getScalarVal(),
    195                                ConvertType(E->getType()));
    196 }
    197 
    198 llvm::Value *CodeGenFunction::EmitObjCArrayLiteral(const ObjCArrayLiteral *E) {
    199   return EmitObjCCollectionLiteral(E, E->getArrayWithObjectsMethod());
    200 }
    201 
    202 llvm::Value *CodeGenFunction::EmitObjCDictionaryLiteral(
    203                                             const ObjCDictionaryLiteral *E) {
    204   return EmitObjCCollectionLiteral(E, E->getDictWithObjectsMethod());
    205 }
    206 
    207 /// Emit a selector.
    208 llvm::Value *CodeGenFunction::EmitObjCSelectorExpr(const ObjCSelectorExpr *E) {
    209   // Untyped selector.
    210   // Note that this implementation allows for non-constant strings to be passed
    211   // as arguments to @selector().  Currently, the only thing preventing this
    212   // behaviour is the type checking in the front end.
    213   return CGM.getObjCRuntime().GetSelector(*this, E->getSelector());
    214 }
    215 
    216 llvm::Value *CodeGenFunction::EmitObjCProtocolExpr(const ObjCProtocolExpr *E) {
    217   // FIXME: This should pass the Decl not the name.
    218   return CGM.getObjCRuntime().GenerateProtocolRef(*this, E->getProtocol());
    219 }
    220 
    221 /// \brief Adjust the type of the result of an Objective-C message send
    222 /// expression when the method has a related result type.
    223 static RValue AdjustRelatedResultType(CodeGenFunction &CGF,
    224                                       QualType ExpT,
    225                                       const ObjCMethodDecl *Method,
    226                                       RValue Result) {
    227   if (!Method)
    228     return Result;
    229 
    230   if (!Method->hasRelatedResultType() ||
    231       CGF.getContext().hasSameType(ExpT, Method->getReturnType()) ||
    232       !Result.isScalar())
    233     return Result;
    234 
    235   // We have applied a related result type. Cast the rvalue appropriately.
    236   return RValue::get(CGF.Builder.CreateBitCast(Result.getScalarVal(),
    237                                                CGF.ConvertType(ExpT)));
    238 }
    239 
    240 /// Decide whether to extend the lifetime of the receiver of a
    241 /// returns-inner-pointer message.
    242 static bool
    243 shouldExtendReceiverForInnerPointerMessage(const ObjCMessageExpr *message) {
    244   switch (message->getReceiverKind()) {
    245 
    246   // For a normal instance message, we should extend unless the
    247   // receiver is loaded from a variable with precise lifetime.
    248   case ObjCMessageExpr::Instance: {
    249     const Expr *receiver = message->getInstanceReceiver();
    250     const ImplicitCastExpr *ice = dyn_cast<ImplicitCastExpr>(receiver);
    251     if (!ice || ice->getCastKind() != CK_LValueToRValue) return true;
    252     receiver = ice->getSubExpr()->IgnoreParens();
    253 
    254     // Only __strong variables.
    255     if (receiver->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
    256       return true;
    257 
    258     // All ivars and fields have precise lifetime.
    259     if (isa<MemberExpr>(receiver) || isa<ObjCIvarRefExpr>(receiver))
    260       return false;
    261 
    262     // Otherwise, check for variables.
    263     const DeclRefExpr *declRef = dyn_cast<DeclRefExpr>(ice->getSubExpr());
    264     if (!declRef) return true;
    265     const VarDecl *var = dyn_cast<VarDecl>(declRef->getDecl());
    266     if (!var) return true;
    267 
    268     // All variables have precise lifetime except local variables with
    269     // automatic storage duration that aren't specially marked.
    270     return (var->hasLocalStorage() &&
    271             !var->hasAttr<ObjCPreciseLifetimeAttr>());
    272   }
    273 
    274   case ObjCMessageExpr::Class:
    275   case ObjCMessageExpr::SuperClass:
    276     // It's never necessary for class objects.
    277     return false;
    278 
    279   case ObjCMessageExpr::SuperInstance:
    280     // We generally assume that 'self' lives throughout a method call.
    281     return false;
    282   }
    283 
    284   llvm_unreachable("invalid receiver kind");
    285 }
    286 
    287 RValue CodeGenFunction::EmitObjCMessageExpr(const ObjCMessageExpr *E,
    288                                             ReturnValueSlot Return) {
    289   // Only the lookup mechanism and first two arguments of the method
    290   // implementation vary between runtimes.  We can get the receiver and
    291   // arguments in generic code.
    292 
    293   bool isDelegateInit = E->isDelegateInitCall();
    294 
    295   const ObjCMethodDecl *method = E->getMethodDecl();
    296 
    297   // We don't retain the receiver in delegate init calls, and this is
    298   // safe because the receiver value is always loaded from 'self',
    299   // which we zero out.  We don't want to Block_copy block receivers,
    300   // though.
    301   bool retainSelf =
    302     (!isDelegateInit &&
    303      CGM.getLangOpts().ObjCAutoRefCount &&
    304      method &&
    305      method->hasAttr<NSConsumesSelfAttr>());
    306 
    307   CGObjCRuntime &Runtime = CGM.getObjCRuntime();
    308   bool isSuperMessage = false;
    309   bool isClassMessage = false;
    310   ObjCInterfaceDecl *OID = nullptr;
    311   // Find the receiver
    312   QualType ReceiverType;
    313   llvm::Value *Receiver = nullptr;
    314   switch (E->getReceiverKind()) {
    315   case ObjCMessageExpr::Instance:
    316     ReceiverType = E->getInstanceReceiver()->getType();
    317     if (retainSelf) {
    318       TryEmitResult ter = tryEmitARCRetainScalarExpr(*this,
    319                                                    E->getInstanceReceiver());
    320       Receiver = ter.getPointer();
    321       if (ter.getInt()) retainSelf = false;
    322     } else
    323       Receiver = EmitScalarExpr(E->getInstanceReceiver());
    324     break;
    325 
    326   case ObjCMessageExpr::Class: {
    327     ReceiverType = E->getClassReceiver();
    328     const ObjCObjectType *ObjTy = ReceiverType->getAs<ObjCObjectType>();
    329     assert(ObjTy && "Invalid Objective-C class message send");
    330     OID = ObjTy->getInterface();
    331     assert(OID && "Invalid Objective-C class message send");
    332     Receiver = Runtime.GetClass(*this, OID);
    333     isClassMessage = true;
    334     break;
    335   }
    336 
    337   case ObjCMessageExpr::SuperInstance:
    338     ReceiverType = E->getSuperType();
    339     Receiver = LoadObjCSelf();
    340     isSuperMessage = true;
    341     break;
    342 
    343   case ObjCMessageExpr::SuperClass:
    344     ReceiverType = E->getSuperType();
    345     Receiver = LoadObjCSelf();
    346     isSuperMessage = true;
    347     isClassMessage = true;
    348     break;
    349   }
    350 
    351   if (retainSelf)
    352     Receiver = EmitARCRetainNonBlock(Receiver);
    353 
    354   // In ARC, we sometimes want to "extend the lifetime"
    355   // (i.e. retain+autorelease) of receivers of returns-inner-pointer
    356   // messages.
    357   if (getLangOpts().ObjCAutoRefCount && method &&
    358       method->hasAttr<ObjCReturnsInnerPointerAttr>() &&
    359       shouldExtendReceiverForInnerPointerMessage(E))
    360     Receiver = EmitARCRetainAutorelease(ReceiverType, Receiver);
    361 
    362   QualType ResultType = method ? method->getReturnType() : E->getType();
    363 
    364   CallArgList Args;
    365   EmitCallArgs(Args, method, E->arg_begin(), E->arg_end());
    366 
    367   // For delegate init calls in ARC, do an unsafe store of null into
    368   // self.  This represents the call taking direct ownership of that
    369   // value.  We have to do this after emitting the other call
    370   // arguments because they might also reference self, but we don't
    371   // have to worry about any of them modifying self because that would
    372   // be an undefined read and write of an object in unordered
    373   // expressions.
    374   if (isDelegateInit) {
    375     assert(getLangOpts().ObjCAutoRefCount &&
    376            "delegate init calls should only be marked in ARC");
    377 
    378     // Do an unsafe store of null into self.
    379     llvm::Value *selfAddr =
    380       LocalDeclMap[cast<ObjCMethodDecl>(CurCodeDecl)->getSelfDecl()];
    381     assert(selfAddr && "no self entry for a delegate init call?");
    382 
    383     Builder.CreateStore(getNullForVariable(selfAddr), selfAddr);
    384   }
    385 
    386   RValue result;
    387   if (isSuperMessage) {
    388     // super is only valid in an Objective-C method
    389     const ObjCMethodDecl *OMD = cast<ObjCMethodDecl>(CurFuncDecl);
    390     bool isCategoryImpl = isa<ObjCCategoryImplDecl>(OMD->getDeclContext());
    391     result = Runtime.GenerateMessageSendSuper(*this, Return, ResultType,
    392                                               E->getSelector(),
    393                                               OMD->getClassInterface(),
    394                                               isCategoryImpl,
    395                                               Receiver,
    396                                               isClassMessage,
    397                                               Args,
    398                                               method);
    399   } else {
    400     result = Runtime.GenerateMessageSend(*this, Return, ResultType,
    401                                          E->getSelector(),
    402                                          Receiver, Args, OID,
    403                                          method);
    404   }
    405 
    406   // For delegate init calls in ARC, implicitly store the result of
    407   // the call back into self.  This takes ownership of the value.
    408   if (isDelegateInit) {
    409     llvm::Value *selfAddr =
    410       LocalDeclMap[cast<ObjCMethodDecl>(CurCodeDecl)->getSelfDecl()];
    411     llvm::Value *newSelf = result.getScalarVal();
    412 
    413     // The delegate return type isn't necessarily a matching type; in
    414     // fact, it's quite likely to be 'id'.
    415     llvm::Type *selfTy =
    416       cast<llvm::PointerType>(selfAddr->getType())->getElementType();
    417     newSelf = Builder.CreateBitCast(newSelf, selfTy);
    418 
    419     Builder.CreateStore(newSelf, selfAddr);
    420   }
    421 
    422   return AdjustRelatedResultType(*this, E->getType(), method, result);
    423 }
    424 
    425 namespace {
    426 struct FinishARCDealloc : EHScopeStack::Cleanup {
    427   void Emit(CodeGenFunction &CGF, Flags flags) override {
    428     const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CGF.CurCodeDecl);
    429 
    430     const ObjCImplDecl *impl = cast<ObjCImplDecl>(method->getDeclContext());
    431     const ObjCInterfaceDecl *iface = impl->getClassInterface();
    432     if (!iface->getSuperClass()) return;
    433 
    434     bool isCategory = isa<ObjCCategoryImplDecl>(impl);
    435 
    436     // Call [super dealloc] if we have a superclass.
    437     llvm::Value *self = CGF.LoadObjCSelf();
    438 
    439     CallArgList args;
    440     CGF.CGM.getObjCRuntime().GenerateMessageSendSuper(CGF, ReturnValueSlot(),
    441                                                       CGF.getContext().VoidTy,
    442                                                       method->getSelector(),
    443                                                       iface,
    444                                                       isCategory,
    445                                                       self,
    446                                                       /*is class msg*/ false,
    447                                                       args,
    448                                                       method);
    449   }
    450 };
    451 }
    452 
    453 /// StartObjCMethod - Begin emission of an ObjCMethod. This generates
    454 /// the LLVM function and sets the other context used by
    455 /// CodeGenFunction.
    456 void CodeGenFunction::StartObjCMethod(const ObjCMethodDecl *OMD,
    457                                       const ObjCContainerDecl *CD) {
    458   SourceLocation StartLoc = OMD->getLocStart();
    459   FunctionArgList args;
    460   // Check if we should generate debug info for this method.
    461   if (OMD->hasAttr<NoDebugAttr>())
    462     DebugInfo = nullptr; // disable debug info indefinitely for this function
    463 
    464   llvm::Function *Fn = CGM.getObjCRuntime().GenerateMethod(OMD, CD);
    465 
    466   const CGFunctionInfo &FI = CGM.getTypes().arrangeObjCMethodDeclaration(OMD);
    467   CGM.SetInternalFunctionAttributes(OMD, Fn, FI);
    468 
    469   args.push_back(OMD->getSelfDecl());
    470   args.push_back(OMD->getCmdDecl());
    471 
    472   args.append(OMD->param_begin(), OMD->param_end());
    473 
    474   CurGD = OMD;
    475   CurEHLocation = OMD->getLocEnd();
    476 
    477   StartFunction(OMD, OMD->getReturnType(), Fn, FI, args,
    478                 OMD->getLocation(), StartLoc);
    479 
    480   // In ARC, certain methods get an extra cleanup.
    481   if (CGM.getLangOpts().ObjCAutoRefCount &&
    482       OMD->isInstanceMethod() &&
    483       OMD->getSelector().isUnarySelector()) {
    484     const IdentifierInfo *ident =
    485       OMD->getSelector().getIdentifierInfoForSlot(0);
    486     if (ident->isStr("dealloc"))
    487       EHStack.pushCleanup<FinishARCDealloc>(getARCCleanupKind());
    488   }
    489 }
    490 
    491 static llvm::Value *emitARCRetainLoadOfScalar(CodeGenFunction &CGF,
    492                                               LValue lvalue, QualType type);
    493 
    494 /// Generate an Objective-C method.  An Objective-C method is a C function with
    495 /// its pointer, name, and types registered in the class struture.
    496 void CodeGenFunction::GenerateObjCMethod(const ObjCMethodDecl *OMD) {
    497   StartObjCMethod(OMD, OMD->getClassInterface());
    498   PGO.assignRegionCounters(OMD, CurFn);
    499   assert(isa<CompoundStmt>(OMD->getBody()));
    500   RegionCounter Cnt = getPGORegionCounter(OMD->getBody());
    501   Cnt.beginRegion(Builder);
    502   EmitCompoundStmtWithoutScope(*cast<CompoundStmt>(OMD->getBody()));
    503   FinishFunction(OMD->getBodyRBrace());
    504 }
    505 
    506 /// emitStructGetterCall - Call the runtime function to load a property
    507 /// into the return value slot.
    508 static void emitStructGetterCall(CodeGenFunction &CGF, ObjCIvarDecl *ivar,
    509                                  bool isAtomic, bool hasStrong) {
    510   ASTContext &Context = CGF.getContext();
    511 
    512   llvm::Value *src =
    513     CGF.EmitLValueForIvar(CGF.TypeOfSelfObject(), CGF.LoadObjCSelf(),
    514                           ivar, 0).getAddress();
    515 
    516   // objc_copyStruct (ReturnValue, &structIvar,
    517   //                  sizeof (Type of Ivar), isAtomic, false);
    518   CallArgList args;
    519 
    520   llvm::Value *dest = CGF.Builder.CreateBitCast(CGF.ReturnValue, CGF.VoidPtrTy);
    521   args.add(RValue::get(dest), Context.VoidPtrTy);
    522 
    523   src = CGF.Builder.CreateBitCast(src, CGF.VoidPtrTy);
    524   args.add(RValue::get(src), Context.VoidPtrTy);
    525 
    526   CharUnits size = CGF.getContext().getTypeSizeInChars(ivar->getType());
    527   args.add(RValue::get(CGF.CGM.getSize(size)), Context.getSizeType());
    528   args.add(RValue::get(CGF.Builder.getInt1(isAtomic)), Context.BoolTy);
    529   args.add(RValue::get(CGF.Builder.getInt1(hasStrong)), Context.BoolTy);
    530 
    531   llvm::Value *fn = CGF.CGM.getObjCRuntime().GetGetStructFunction();
    532   CGF.EmitCall(CGF.getTypes().arrangeFreeFunctionCall(Context.VoidTy, args,
    533                                                       FunctionType::ExtInfo(),
    534                                                       RequiredArgs::All),
    535                fn, ReturnValueSlot(), args);
    536 }
    537 
    538 /// Determine whether the given architecture supports unaligned atomic
    539 /// accesses.  They don't have to be fast, just faster than a function
    540 /// call and a mutex.
    541 static bool hasUnalignedAtomics(llvm::Triple::ArchType arch) {
    542   // FIXME: Allow unaligned atomic load/store on x86.  (It is not
    543   // currently supported by the backend.)
    544   return 0;
    545 }
    546 
    547 /// Return the maximum size that permits atomic accesses for the given
    548 /// architecture.
    549 static CharUnits getMaxAtomicAccessSize(CodeGenModule &CGM,
    550                                         llvm::Triple::ArchType arch) {
    551   // ARM has 8-byte atomic accesses, but it's not clear whether we
    552   // want to rely on them here.
    553 
    554   // In the default case, just assume that any size up to a pointer is
    555   // fine given adequate alignment.
    556   return CharUnits::fromQuantity(CGM.PointerSizeInBytes);
    557 }
    558 
    559 namespace {
    560   class PropertyImplStrategy {
    561   public:
    562     enum StrategyKind {
    563       /// The 'native' strategy is to use the architecture's provided
    564       /// reads and writes.
    565       Native,
    566 
    567       /// Use objc_setProperty and objc_getProperty.
    568       GetSetProperty,
    569 
    570       /// Use objc_setProperty for the setter, but use expression
    571       /// evaluation for the getter.
    572       SetPropertyAndExpressionGet,
    573 
    574       /// Use objc_copyStruct.
    575       CopyStruct,
    576 
    577       /// The 'expression' strategy is to emit normal assignment or
    578       /// lvalue-to-rvalue expressions.
    579       Expression
    580     };
    581 
    582     StrategyKind getKind() const { return StrategyKind(Kind); }
    583 
    584     bool hasStrongMember() const { return HasStrong; }
    585     bool isAtomic() const { return IsAtomic; }
    586     bool isCopy() const { return IsCopy; }
    587 
    588     CharUnits getIvarSize() const { return IvarSize; }
    589     CharUnits getIvarAlignment() const { return IvarAlignment; }
    590 
    591     PropertyImplStrategy(CodeGenModule &CGM,
    592                          const ObjCPropertyImplDecl *propImpl);
    593 
    594   private:
    595     unsigned Kind : 8;
    596     unsigned IsAtomic : 1;
    597     unsigned IsCopy : 1;
    598     unsigned HasStrong : 1;
    599 
    600     CharUnits IvarSize;
    601     CharUnits IvarAlignment;
    602   };
    603 }
    604 
    605 /// Pick an implementation strategy for the given property synthesis.
    606 PropertyImplStrategy::PropertyImplStrategy(CodeGenModule &CGM,
    607                                      const ObjCPropertyImplDecl *propImpl) {
    608   const ObjCPropertyDecl *prop = propImpl->getPropertyDecl();
    609   ObjCPropertyDecl::SetterKind setterKind = prop->getSetterKind();
    610 
    611   IsCopy = (setterKind == ObjCPropertyDecl::Copy);
    612   IsAtomic = prop->isAtomic();
    613   HasStrong = false; // doesn't matter here.
    614 
    615   // Evaluate the ivar's size and alignment.
    616   ObjCIvarDecl *ivar = propImpl->getPropertyIvarDecl();
    617   QualType ivarType = ivar->getType();
    618   std::tie(IvarSize, IvarAlignment) =
    619       CGM.getContext().getTypeInfoInChars(ivarType);
    620 
    621   // If we have a copy property, we always have to use getProperty/setProperty.
    622   // TODO: we could actually use setProperty and an expression for non-atomics.
    623   if (IsCopy) {
    624     Kind = GetSetProperty;
    625     return;
    626   }
    627 
    628   // Handle retain.
    629   if (setterKind == ObjCPropertyDecl::Retain) {
    630     // In GC-only, there's nothing special that needs to be done.
    631     if (CGM.getLangOpts().getGC() == LangOptions::GCOnly) {
    632       // fallthrough
    633 
    634     // In ARC, if the property is non-atomic, use expression emission,
    635     // which translates to objc_storeStrong.  This isn't required, but
    636     // it's slightly nicer.
    637     } else if (CGM.getLangOpts().ObjCAutoRefCount && !IsAtomic) {
    638       // Using standard expression emission for the setter is only
    639       // acceptable if the ivar is __strong, which won't be true if
    640       // the property is annotated with __attribute__((NSObject)).
    641       // TODO: falling all the way back to objc_setProperty here is
    642       // just laziness, though;  we could still use objc_storeStrong
    643       // if we hacked it right.
    644       if (ivarType.getObjCLifetime() == Qualifiers::OCL_Strong)
    645         Kind = Expression;
    646       else
    647         Kind = SetPropertyAndExpressionGet;
    648       return;
    649 
    650     // Otherwise, we need to at least use setProperty.  However, if
    651     // the property isn't atomic, we can use normal expression
    652     // emission for the getter.
    653     } else if (!IsAtomic) {
    654       Kind = SetPropertyAndExpressionGet;
    655       return;
    656 
    657     // Otherwise, we have to use both setProperty and getProperty.
    658     } else {
    659       Kind = GetSetProperty;
    660       return;
    661     }
    662   }
    663 
    664   // If we're not atomic, just use expression accesses.
    665   if (!IsAtomic) {
    666     Kind = Expression;
    667     return;
    668   }
    669 
    670   // Properties on bitfield ivars need to be emitted using expression
    671   // accesses even if they're nominally atomic.
    672   if (ivar->isBitField()) {
    673     Kind = Expression;
    674     return;
    675   }
    676 
    677   // GC-qualified or ARC-qualified ivars need to be emitted as
    678   // expressions.  This actually works out to being atomic anyway,
    679   // except for ARC __strong, but that should trigger the above code.
    680   if (ivarType.hasNonTrivialObjCLifetime() ||
    681       (CGM.getLangOpts().getGC() &&
    682        CGM.getContext().getObjCGCAttrKind(ivarType))) {
    683     Kind = Expression;
    684     return;
    685   }
    686 
    687   // Compute whether the ivar has strong members.
    688   if (CGM.getLangOpts().getGC())
    689     if (const RecordType *recordType = ivarType->getAs<RecordType>())
    690       HasStrong = recordType->getDecl()->hasObjectMember();
    691 
    692   // We can never access structs with object members with a native
    693   // access, because we need to use write barriers.  This is what
    694   // objc_copyStruct is for.
    695   if (HasStrong) {
    696     Kind = CopyStruct;
    697     return;
    698   }
    699 
    700   // Otherwise, this is target-dependent and based on the size and
    701   // alignment of the ivar.
    702 
    703   // If the size of the ivar is not a power of two, give up.  We don't
    704   // want to get into the business of doing compare-and-swaps.
    705   if (!IvarSize.isPowerOfTwo()) {
    706     Kind = CopyStruct;
    707     return;
    708   }
    709 
    710   llvm::Triple::ArchType arch =
    711     CGM.getTarget().getTriple().getArch();
    712 
    713   // Most architectures require memory to fit within a single cache
    714   // line, so the alignment has to be at least the size of the access.
    715   // Otherwise we have to grab a lock.
    716   if (IvarAlignment < IvarSize && !hasUnalignedAtomics(arch)) {
    717     Kind = CopyStruct;
    718     return;
    719   }
    720 
    721   // If the ivar's size exceeds the architecture's maximum atomic
    722   // access size, we have to use CopyStruct.
    723   if (IvarSize > getMaxAtomicAccessSize(CGM, arch)) {
    724     Kind = CopyStruct;
    725     return;
    726   }
    727 
    728   // Otherwise, we can use native loads and stores.
    729   Kind = Native;
    730 }
    731 
    732 /// \brief Generate an Objective-C property getter function.
    733 ///
    734 /// The given Decl must be an ObjCImplementationDecl. \@synthesize
    735 /// is illegal within a category.
    736 void CodeGenFunction::GenerateObjCGetter(ObjCImplementationDecl *IMP,
    737                                          const ObjCPropertyImplDecl *PID) {
    738   llvm::Constant *AtomicHelperFn =
    739       CodeGenFunction(CGM).GenerateObjCAtomicGetterCopyHelperFunction(PID);
    740   const ObjCPropertyDecl *PD = PID->getPropertyDecl();
    741   ObjCMethodDecl *OMD = PD->getGetterMethodDecl();
    742   assert(OMD && "Invalid call to generate getter (empty method)");
    743   StartObjCMethod(OMD, IMP->getClassInterface());
    744 
    745   generateObjCGetterBody(IMP, PID, OMD, AtomicHelperFn);
    746 
    747   FinishFunction();
    748 }
    749 
    750 static bool hasTrivialGetExpr(const ObjCPropertyImplDecl *propImpl) {
    751   const Expr *getter = propImpl->getGetterCXXConstructor();
    752   if (!getter) return true;
    753 
    754   // Sema only makes only of these when the ivar has a C++ class type,
    755   // so the form is pretty constrained.
    756 
    757   // If the property has a reference type, we might just be binding a
    758   // reference, in which case the result will be a gl-value.  We should
    759   // treat this as a non-trivial operation.
    760   if (getter->isGLValue())
    761     return false;
    762 
    763   // If we selected a trivial copy-constructor, we're okay.
    764   if (const CXXConstructExpr *construct = dyn_cast<CXXConstructExpr>(getter))
    765     return (construct->getConstructor()->isTrivial());
    766 
    767   // The constructor might require cleanups (in which case it's never
    768   // trivial).
    769   assert(isa<ExprWithCleanups>(getter));
    770   return false;
    771 }
    772 
    773 /// emitCPPObjectAtomicGetterCall - Call the runtime function to
    774 /// copy the ivar into the resturn slot.
    775 static void emitCPPObjectAtomicGetterCall(CodeGenFunction &CGF,
    776                                           llvm::Value *returnAddr,
    777                                           ObjCIvarDecl *ivar,
    778                                           llvm::Constant *AtomicHelperFn) {
    779   // objc_copyCppObjectAtomic (&returnSlot, &CppObjectIvar,
    780   //                           AtomicHelperFn);
    781   CallArgList args;
    782 
    783   // The 1st argument is the return Slot.
    784   args.add(RValue::get(returnAddr), CGF.getContext().VoidPtrTy);
    785 
    786   // The 2nd argument is the address of the ivar.
    787   llvm::Value *ivarAddr =
    788   CGF.EmitLValueForIvar(CGF.TypeOfSelfObject(),
    789                         CGF.LoadObjCSelf(), ivar, 0).getAddress();
    790   ivarAddr = CGF.Builder.CreateBitCast(ivarAddr, CGF.Int8PtrTy);
    791   args.add(RValue::get(ivarAddr), CGF.getContext().VoidPtrTy);
    792 
    793   // Third argument is the helper function.
    794   args.add(RValue::get(AtomicHelperFn), CGF.getContext().VoidPtrTy);
    795 
    796   llvm::Value *copyCppAtomicObjectFn =
    797     CGF.CGM.getObjCRuntime().GetCppAtomicObjectGetFunction();
    798   CGF.EmitCall(CGF.getTypes().arrangeFreeFunctionCall(CGF.getContext().VoidTy,
    799                                                       args,
    800                                                       FunctionType::ExtInfo(),
    801                                                       RequiredArgs::All),
    802                copyCppAtomicObjectFn, ReturnValueSlot(), args);
    803 }
    804 
    805 void
    806 CodeGenFunction::generateObjCGetterBody(const ObjCImplementationDecl *classImpl,
    807                                         const ObjCPropertyImplDecl *propImpl,
    808                                         const ObjCMethodDecl *GetterMethodDecl,
    809                                         llvm::Constant *AtomicHelperFn) {
    810   // If there's a non-trivial 'get' expression, we just have to emit that.
    811   if (!hasTrivialGetExpr(propImpl)) {
    812     if (!AtomicHelperFn) {
    813       ReturnStmt ret(SourceLocation(), propImpl->getGetterCXXConstructor(),
    814                      /*nrvo*/ nullptr);
    815       EmitReturnStmt(ret);
    816     }
    817     else {
    818       ObjCIvarDecl *ivar = propImpl->getPropertyIvarDecl();
    819       emitCPPObjectAtomicGetterCall(*this, ReturnValue,
    820                                     ivar, AtomicHelperFn);
    821     }
    822     return;
    823   }
    824 
    825   const ObjCPropertyDecl *prop = propImpl->getPropertyDecl();
    826   QualType propType = prop->getType();
    827   ObjCMethodDecl *getterMethod = prop->getGetterMethodDecl();
    828 
    829   ObjCIvarDecl *ivar = propImpl->getPropertyIvarDecl();
    830 
    831   // Pick an implementation strategy.
    832   PropertyImplStrategy strategy(CGM, propImpl);
    833   switch (strategy.getKind()) {
    834   case PropertyImplStrategy::Native: {
    835     // We don't need to do anything for a zero-size struct.
    836     if (strategy.getIvarSize().isZero())
    837       return;
    838 
    839     LValue LV = EmitLValueForIvar(TypeOfSelfObject(), LoadObjCSelf(), ivar, 0);
    840 
    841     // Currently, all atomic accesses have to be through integer
    842     // types, so there's no point in trying to pick a prettier type.
    843     llvm::Type *bitcastType =
    844       llvm::Type::getIntNTy(getLLVMContext(),
    845                             getContext().toBits(strategy.getIvarSize()));
    846     bitcastType = bitcastType->getPointerTo(); // addrspace 0 okay
    847 
    848     // Perform an atomic load.  This does not impose ordering constraints.
    849     llvm::Value *ivarAddr = LV.getAddress();
    850     ivarAddr = Builder.CreateBitCast(ivarAddr, bitcastType);
    851     llvm::LoadInst *load = Builder.CreateLoad(ivarAddr, "load");
    852     load->setAlignment(strategy.getIvarAlignment().getQuantity());
    853     load->setAtomic(llvm::Unordered);
    854 
    855     // Store that value into the return address.  Doing this with a
    856     // bitcast is likely to produce some pretty ugly IR, but it's not
    857     // the *most* terrible thing in the world.
    858     Builder.CreateStore(load, Builder.CreateBitCast(ReturnValue, bitcastType));
    859 
    860     // Make sure we don't do an autorelease.
    861     AutoreleaseResult = false;
    862     return;
    863   }
    864 
    865   case PropertyImplStrategy::GetSetProperty: {
    866     llvm::Value *getPropertyFn =
    867       CGM.getObjCRuntime().GetPropertyGetFunction();
    868     if (!getPropertyFn) {
    869       CGM.ErrorUnsupported(propImpl, "Obj-C getter requiring atomic copy");
    870       return;
    871     }
    872 
    873     // Return (ivar-type) objc_getProperty((id) self, _cmd, offset, true).
    874     // FIXME: Can't this be simpler? This might even be worse than the
    875     // corresponding gcc code.
    876     llvm::Value *cmd =
    877       Builder.CreateLoad(LocalDeclMap[getterMethod->getCmdDecl()], "cmd");
    878     llvm::Value *self = Builder.CreateBitCast(LoadObjCSelf(), VoidPtrTy);
    879     llvm::Value *ivarOffset =
    880       EmitIvarOffset(classImpl->getClassInterface(), ivar);
    881 
    882     CallArgList args;
    883     args.add(RValue::get(self), getContext().getObjCIdType());
    884     args.add(RValue::get(cmd), getContext().getObjCSelType());
    885     args.add(RValue::get(ivarOffset), getContext().getPointerDiffType());
    886     args.add(RValue::get(Builder.getInt1(strategy.isAtomic())),
    887              getContext().BoolTy);
    888 
    889     // FIXME: We shouldn't need to get the function info here, the
    890     // runtime already should have computed it to build the function.
    891     llvm::Instruction *CallInstruction;
    892     RValue RV = EmitCall(getTypes().arrangeFreeFunctionCall(propType, args,
    893                                                        FunctionType::ExtInfo(),
    894                                                             RequiredArgs::All),
    895                          getPropertyFn, ReturnValueSlot(), args, nullptr,
    896                          &CallInstruction);
    897     if (llvm::CallInst *call = dyn_cast<llvm::CallInst>(CallInstruction))
    898       call->setTailCall();
    899 
    900     // We need to fix the type here. Ivars with copy & retain are
    901     // always objects so we don't need to worry about complex or
    902     // aggregates.
    903     RV = RValue::get(Builder.CreateBitCast(
    904         RV.getScalarVal(),
    905         getTypes().ConvertType(getterMethod->getReturnType())));
    906 
    907     EmitReturnOfRValue(RV, propType);
    908 
    909     // objc_getProperty does an autorelease, so we should suppress ours.
    910     AutoreleaseResult = false;
    911 
    912     return;
    913   }
    914 
    915   case PropertyImplStrategy::CopyStruct:
    916     emitStructGetterCall(*this, ivar, strategy.isAtomic(),
    917                          strategy.hasStrongMember());
    918     return;
    919 
    920   case PropertyImplStrategy::Expression:
    921   case PropertyImplStrategy::SetPropertyAndExpressionGet: {
    922     LValue LV = EmitLValueForIvar(TypeOfSelfObject(), LoadObjCSelf(), ivar, 0);
    923 
    924     QualType ivarType = ivar->getType();
    925     switch (getEvaluationKind(ivarType)) {
    926     case TEK_Complex: {
    927       ComplexPairTy pair = EmitLoadOfComplex(LV, SourceLocation());
    928       EmitStoreOfComplex(pair,
    929                          MakeNaturalAlignAddrLValue(ReturnValue, ivarType),
    930                          /*init*/ true);
    931       return;
    932     }
    933     case TEK_Aggregate:
    934       // The return value slot is guaranteed to not be aliased, but
    935       // that's not necessarily the same as "on the stack", so
    936       // we still potentially need objc_memmove_collectable.
    937       EmitAggregateCopy(ReturnValue, LV.getAddress(), ivarType);
    938       return;
    939     case TEK_Scalar: {
    940       llvm::Value *value;
    941       if (propType->isReferenceType()) {
    942         value = LV.getAddress();
    943       } else {
    944         // We want to load and autoreleaseReturnValue ARC __weak ivars.
    945         if (LV.getQuals().getObjCLifetime() == Qualifiers::OCL_Weak) {
    946           value = emitARCRetainLoadOfScalar(*this, LV, ivarType);
    947 
    948         // Otherwise we want to do a simple load, suppressing the
    949         // final autorelease.
    950         } else {
    951           value = EmitLoadOfLValue(LV, SourceLocation()).getScalarVal();
    952           AutoreleaseResult = false;
    953         }
    954 
    955         value = Builder.CreateBitCast(value, ConvertType(propType));
    956         value = Builder.CreateBitCast(
    957             value, ConvertType(GetterMethodDecl->getReturnType()));
    958       }
    959 
    960       EmitReturnOfRValue(RValue::get(value), propType);
    961       return;
    962     }
    963     }
    964     llvm_unreachable("bad evaluation kind");
    965   }
    966 
    967   }
    968   llvm_unreachable("bad @property implementation strategy!");
    969 }
    970 
    971 /// emitStructSetterCall - Call the runtime function to store the value
    972 /// from the first formal parameter into the given ivar.
    973 static void emitStructSetterCall(CodeGenFunction &CGF, ObjCMethodDecl *OMD,
    974                                  ObjCIvarDecl *ivar) {
    975   // objc_copyStruct (&structIvar, &Arg,
    976   //                  sizeof (struct something), true, false);
    977   CallArgList args;
    978 
    979   // The first argument is the address of the ivar.
    980   llvm::Value *ivarAddr = CGF.EmitLValueForIvar(CGF.TypeOfSelfObject(),
    981                                                 CGF.LoadObjCSelf(), ivar, 0)
    982     .getAddress();
    983   ivarAddr = CGF.Builder.CreateBitCast(ivarAddr, CGF.Int8PtrTy);
    984   args.add(RValue::get(ivarAddr), CGF.getContext().VoidPtrTy);
    985 
    986   // The second argument is the address of the parameter variable.
    987   ParmVarDecl *argVar = *OMD->param_begin();
    988   DeclRefExpr argRef(argVar, false, argVar->getType().getNonReferenceType(),
    989                      VK_LValue, SourceLocation());
    990   llvm::Value *argAddr = CGF.EmitLValue(&argRef).getAddress();
    991   argAddr = CGF.Builder.CreateBitCast(argAddr, CGF.Int8PtrTy);
    992   args.add(RValue::get(argAddr), CGF.getContext().VoidPtrTy);
    993 
    994   // The third argument is the sizeof the type.
    995   llvm::Value *size =
    996     CGF.CGM.getSize(CGF.getContext().getTypeSizeInChars(ivar->getType()));
    997   args.add(RValue::get(size), CGF.getContext().getSizeType());
    998 
    999   // The fourth argument is the 'isAtomic' flag.
   1000   args.add(RValue::get(CGF.Builder.getTrue()), CGF.getContext().BoolTy);
   1001 
   1002   // The fifth argument is the 'hasStrong' flag.
   1003   // FIXME: should this really always be false?
   1004   args.add(RValue::get(CGF.Builder.getFalse()), CGF.getContext().BoolTy);
   1005 
   1006   llvm::Value *copyStructFn = CGF.CGM.getObjCRuntime().GetSetStructFunction();
   1007   CGF.EmitCall(CGF.getTypes().arrangeFreeFunctionCall(CGF.getContext().VoidTy,
   1008                                                       args,
   1009                                                       FunctionType::ExtInfo(),
   1010                                                       RequiredArgs::All),
   1011                copyStructFn, ReturnValueSlot(), args);
   1012 }
   1013 
   1014 /// emitCPPObjectAtomicSetterCall - Call the runtime function to store
   1015 /// the value from the first formal parameter into the given ivar, using
   1016 /// the Cpp API for atomic Cpp objects with non-trivial copy assignment.
   1017 static void emitCPPObjectAtomicSetterCall(CodeGenFunction &CGF,
   1018                                           ObjCMethodDecl *OMD,
   1019                                           ObjCIvarDecl *ivar,
   1020                                           llvm::Constant *AtomicHelperFn) {
   1021   // objc_copyCppObjectAtomic (&CppObjectIvar, &Arg,
   1022   //                           AtomicHelperFn);
   1023   CallArgList args;
   1024 
   1025   // The first argument is the address of the ivar.
   1026   llvm::Value *ivarAddr =
   1027     CGF.EmitLValueForIvar(CGF.TypeOfSelfObject(),
   1028                           CGF.LoadObjCSelf(), ivar, 0).getAddress();
   1029   ivarAddr = CGF.Builder.CreateBitCast(ivarAddr, CGF.Int8PtrTy);
   1030   args.add(RValue::get(ivarAddr), CGF.getContext().VoidPtrTy);
   1031 
   1032   // The second argument is the address of the parameter variable.
   1033   ParmVarDecl *argVar = *OMD->param_begin();
   1034   DeclRefExpr argRef(argVar, false, argVar->getType().getNonReferenceType(),
   1035                      VK_LValue, SourceLocation());
   1036   llvm::Value *argAddr = CGF.EmitLValue(&argRef).getAddress();
   1037   argAddr = CGF.Builder.CreateBitCast(argAddr, CGF.Int8PtrTy);
   1038   args.add(RValue::get(argAddr), CGF.getContext().VoidPtrTy);
   1039 
   1040   // Third argument is the helper function.
   1041   args.add(RValue::get(AtomicHelperFn), CGF.getContext().VoidPtrTy);
   1042 
   1043   llvm::Value *copyCppAtomicObjectFn =
   1044     CGF.CGM.getObjCRuntime().GetCppAtomicObjectSetFunction();
   1045   CGF.EmitCall(CGF.getTypes().arrangeFreeFunctionCall(CGF.getContext().VoidTy,
   1046                                                       args,
   1047                                                       FunctionType::ExtInfo(),
   1048                                                       RequiredArgs::All),
   1049                copyCppAtomicObjectFn, ReturnValueSlot(), args);
   1050 }
   1051 
   1052 
   1053 static bool hasTrivialSetExpr(const ObjCPropertyImplDecl *PID) {
   1054   Expr *setter = PID->getSetterCXXAssignment();
   1055   if (!setter) return true;
   1056 
   1057   // Sema only makes only of these when the ivar has a C++ class type,
   1058   // so the form is pretty constrained.
   1059 
   1060   // An operator call is trivial if the function it calls is trivial.
   1061   // This also implies that there's nothing non-trivial going on with
   1062   // the arguments, because operator= can only be trivial if it's a
   1063   // synthesized assignment operator and therefore both parameters are
   1064   // references.
   1065   if (CallExpr *call = dyn_cast<CallExpr>(setter)) {
   1066     if (const FunctionDecl *callee
   1067           = dyn_cast_or_null<FunctionDecl>(call->getCalleeDecl()))
   1068       if (callee->isTrivial())
   1069         return true;
   1070     return false;
   1071   }
   1072 
   1073   assert(isa<ExprWithCleanups>(setter));
   1074   return false;
   1075 }
   1076 
   1077 static bool UseOptimizedSetter(CodeGenModule &CGM) {
   1078   if (CGM.getLangOpts().getGC() != LangOptions::NonGC)
   1079     return false;
   1080   return CGM.getLangOpts().ObjCRuntime.hasOptimizedSetter();
   1081 }
   1082 
   1083 void
   1084 CodeGenFunction::generateObjCSetterBody(const ObjCImplementationDecl *classImpl,
   1085                                         const ObjCPropertyImplDecl *propImpl,
   1086                                         llvm::Constant *AtomicHelperFn) {
   1087   const ObjCPropertyDecl *prop = propImpl->getPropertyDecl();
   1088   ObjCIvarDecl *ivar = propImpl->getPropertyIvarDecl();
   1089   ObjCMethodDecl *setterMethod = prop->getSetterMethodDecl();
   1090 
   1091   // Just use the setter expression if Sema gave us one and it's
   1092   // non-trivial.
   1093   if (!hasTrivialSetExpr(propImpl)) {
   1094     if (!AtomicHelperFn)
   1095       // If non-atomic, assignment is called directly.
   1096       EmitStmt(propImpl->getSetterCXXAssignment());
   1097     else
   1098       // If atomic, assignment is called via a locking api.
   1099       emitCPPObjectAtomicSetterCall(*this, setterMethod, ivar,
   1100                                     AtomicHelperFn);
   1101     return;
   1102   }
   1103 
   1104   PropertyImplStrategy strategy(CGM, propImpl);
   1105   switch (strategy.getKind()) {
   1106   case PropertyImplStrategy::Native: {
   1107     // We don't need to do anything for a zero-size struct.
   1108     if (strategy.getIvarSize().isZero())
   1109       return;
   1110 
   1111     llvm::Value *argAddr = LocalDeclMap[*setterMethod->param_begin()];
   1112 
   1113     LValue ivarLValue =
   1114       EmitLValueForIvar(TypeOfSelfObject(), LoadObjCSelf(), ivar, /*quals*/ 0);
   1115     llvm::Value *ivarAddr = ivarLValue.getAddress();
   1116 
   1117     // Currently, all atomic accesses have to be through integer
   1118     // types, so there's no point in trying to pick a prettier type.
   1119     llvm::Type *bitcastType =
   1120       llvm::Type::getIntNTy(getLLVMContext(),
   1121                             getContext().toBits(strategy.getIvarSize()));
   1122     bitcastType = bitcastType->getPointerTo(); // addrspace 0 okay
   1123 
   1124     // Cast both arguments to the chosen operation type.
   1125     argAddr = Builder.CreateBitCast(argAddr, bitcastType);
   1126     ivarAddr = Builder.CreateBitCast(ivarAddr, bitcastType);
   1127 
   1128     // This bitcast load is likely to cause some nasty IR.
   1129     llvm::Value *load = Builder.CreateLoad(argAddr);
   1130 
   1131     // Perform an atomic store.  There are no memory ordering requirements.
   1132     llvm::StoreInst *store = Builder.CreateStore(load, ivarAddr);
   1133     store->setAlignment(strategy.getIvarAlignment().getQuantity());
   1134     store->setAtomic(llvm::Unordered);
   1135     return;
   1136   }
   1137 
   1138   case PropertyImplStrategy::GetSetProperty:
   1139   case PropertyImplStrategy::SetPropertyAndExpressionGet: {
   1140 
   1141     llvm::Value *setOptimizedPropertyFn = nullptr;
   1142     llvm::Value *setPropertyFn = nullptr;
   1143     if (UseOptimizedSetter(CGM)) {
   1144       // 10.8 and iOS 6.0 code and GC is off
   1145       setOptimizedPropertyFn =
   1146         CGM.getObjCRuntime()
   1147            .GetOptimizedPropertySetFunction(strategy.isAtomic(),
   1148                                             strategy.isCopy());
   1149       if (!setOptimizedPropertyFn) {
   1150         CGM.ErrorUnsupported(propImpl, "Obj-C optimized setter - NYI");
   1151         return;
   1152       }
   1153     }
   1154     else {
   1155       setPropertyFn = CGM.getObjCRuntime().GetPropertySetFunction();
   1156       if (!setPropertyFn) {
   1157         CGM.ErrorUnsupported(propImpl, "Obj-C setter requiring atomic copy");
   1158         return;
   1159       }
   1160     }
   1161 
   1162     // Emit objc_setProperty((id) self, _cmd, offset, arg,
   1163     //                       <is-atomic>, <is-copy>).
   1164     llvm::Value *cmd =
   1165       Builder.CreateLoad(LocalDeclMap[setterMethod->getCmdDecl()]);
   1166     llvm::Value *self =
   1167       Builder.CreateBitCast(LoadObjCSelf(), VoidPtrTy);
   1168     llvm::Value *ivarOffset =
   1169       EmitIvarOffset(classImpl->getClassInterface(), ivar);
   1170     llvm::Value *arg = LocalDeclMap[*setterMethod->param_begin()];
   1171     arg = Builder.CreateBitCast(Builder.CreateLoad(arg, "arg"), VoidPtrTy);
   1172 
   1173     CallArgList args;
   1174     args.add(RValue::get(self), getContext().getObjCIdType());
   1175     args.add(RValue::get(cmd), getContext().getObjCSelType());
   1176     if (setOptimizedPropertyFn) {
   1177       args.add(RValue::get(arg), getContext().getObjCIdType());
   1178       args.add(RValue::get(ivarOffset), getContext().getPointerDiffType());
   1179       EmitCall(getTypes().arrangeFreeFunctionCall(getContext().VoidTy, args,
   1180                                                   FunctionType::ExtInfo(),
   1181                                                   RequiredArgs::All),
   1182                setOptimizedPropertyFn, ReturnValueSlot(), args);
   1183     } else {
   1184       args.add(RValue::get(ivarOffset), getContext().getPointerDiffType());
   1185       args.add(RValue::get(arg), getContext().getObjCIdType());
   1186       args.add(RValue::get(Builder.getInt1(strategy.isAtomic())),
   1187                getContext().BoolTy);
   1188       args.add(RValue::get(Builder.getInt1(strategy.isCopy())),
   1189                getContext().BoolTy);
   1190       // FIXME: We shouldn't need to get the function info here, the runtime
   1191       // already should have computed it to build the function.
   1192       EmitCall(getTypes().arrangeFreeFunctionCall(getContext().VoidTy, args,
   1193                                                   FunctionType::ExtInfo(),
   1194                                                   RequiredArgs::All),
   1195                setPropertyFn, ReturnValueSlot(), args);
   1196     }
   1197 
   1198     return;
   1199   }
   1200 
   1201   case PropertyImplStrategy::CopyStruct:
   1202     emitStructSetterCall(*this, setterMethod, ivar);
   1203     return;
   1204 
   1205   case PropertyImplStrategy::Expression:
   1206     break;
   1207   }
   1208 
   1209   // Otherwise, fake up some ASTs and emit a normal assignment.
   1210   ValueDecl *selfDecl = setterMethod->getSelfDecl();
   1211   DeclRefExpr self(selfDecl, false, selfDecl->getType(),
   1212                    VK_LValue, SourceLocation());
   1213   ImplicitCastExpr selfLoad(ImplicitCastExpr::OnStack,
   1214                             selfDecl->getType(), CK_LValueToRValue, &self,
   1215                             VK_RValue);
   1216   ObjCIvarRefExpr ivarRef(ivar, ivar->getType().getNonReferenceType(),
   1217                           SourceLocation(), SourceLocation(),
   1218                           &selfLoad, true, true);
   1219 
   1220   ParmVarDecl *argDecl = *setterMethod->param_begin();
   1221   QualType argType = argDecl->getType().getNonReferenceType();
   1222   DeclRefExpr arg(argDecl, false, argType, VK_LValue, SourceLocation());
   1223   ImplicitCastExpr argLoad(ImplicitCastExpr::OnStack,
   1224                            argType.getUnqualifiedType(), CK_LValueToRValue,
   1225                            &arg, VK_RValue);
   1226 
   1227   // The property type can differ from the ivar type in some situations with
   1228   // Objective-C pointer types, we can always bit cast the RHS in these cases.
   1229   // The following absurdity is just to ensure well-formed IR.
   1230   CastKind argCK = CK_NoOp;
   1231   if (ivarRef.getType()->isObjCObjectPointerType()) {
   1232     if (argLoad.getType()->isObjCObjectPointerType())
   1233       argCK = CK_BitCast;
   1234     else if (argLoad.getType()->isBlockPointerType())
   1235       argCK = CK_BlockPointerToObjCPointerCast;
   1236     else
   1237       argCK = CK_CPointerToObjCPointerCast;
   1238   } else if (ivarRef.getType()->isBlockPointerType()) {
   1239      if (argLoad.getType()->isBlockPointerType())
   1240       argCK = CK_BitCast;
   1241     else
   1242       argCK = CK_AnyPointerToBlockPointerCast;
   1243   } else if (ivarRef.getType()->isPointerType()) {
   1244     argCK = CK_BitCast;
   1245   }
   1246   ImplicitCastExpr argCast(ImplicitCastExpr::OnStack,
   1247                            ivarRef.getType(), argCK, &argLoad,
   1248                            VK_RValue);
   1249   Expr *finalArg = &argLoad;
   1250   if (!getContext().hasSameUnqualifiedType(ivarRef.getType(),
   1251                                            argLoad.getType()))
   1252     finalArg = &argCast;
   1253 
   1254 
   1255   BinaryOperator assign(&ivarRef, finalArg, BO_Assign,
   1256                         ivarRef.getType(), VK_RValue, OK_Ordinary,
   1257                         SourceLocation(), false);
   1258   EmitStmt(&assign);
   1259 }
   1260 
   1261 /// \brief Generate an Objective-C property setter function.
   1262 ///
   1263 /// The given Decl must be an ObjCImplementationDecl. \@synthesize
   1264 /// is illegal within a category.
   1265 void CodeGenFunction::GenerateObjCSetter(ObjCImplementationDecl *IMP,
   1266                                          const ObjCPropertyImplDecl *PID) {
   1267   llvm::Constant *AtomicHelperFn =
   1268       CodeGenFunction(CGM).GenerateObjCAtomicSetterCopyHelperFunction(PID);
   1269   const ObjCPropertyDecl *PD = PID->getPropertyDecl();
   1270   ObjCMethodDecl *OMD = PD->getSetterMethodDecl();
   1271   assert(OMD && "Invalid call to generate setter (empty method)");
   1272   StartObjCMethod(OMD, IMP->getClassInterface());
   1273 
   1274   generateObjCSetterBody(IMP, PID, AtomicHelperFn);
   1275 
   1276   FinishFunction();
   1277 }
   1278 
   1279 namespace {
   1280   struct DestroyIvar : EHScopeStack::Cleanup {
   1281   private:
   1282     llvm::Value *addr;
   1283     const ObjCIvarDecl *ivar;
   1284     CodeGenFunction::Destroyer *destroyer;
   1285     bool useEHCleanupForArray;
   1286   public:
   1287     DestroyIvar(llvm::Value *addr, const ObjCIvarDecl *ivar,
   1288                 CodeGenFunction::Destroyer *destroyer,
   1289                 bool useEHCleanupForArray)
   1290       : addr(addr), ivar(ivar), destroyer(destroyer),
   1291         useEHCleanupForArray(useEHCleanupForArray) {}
   1292 
   1293     void Emit(CodeGenFunction &CGF, Flags flags) override {
   1294       LValue lvalue
   1295         = CGF.EmitLValueForIvar(CGF.TypeOfSelfObject(), addr, ivar, /*CVR*/ 0);
   1296       CGF.emitDestroy(lvalue.getAddress(), ivar->getType(), destroyer,
   1297                       flags.isForNormalCleanup() && useEHCleanupForArray);
   1298     }
   1299   };
   1300 }
   1301 
   1302 /// Like CodeGenFunction::destroyARCStrong, but do it with a call.
   1303 static void destroyARCStrongWithStore(CodeGenFunction &CGF,
   1304                                       llvm::Value *addr,
   1305                                       QualType type) {
   1306   llvm::Value *null = getNullForVariable(addr);
   1307   CGF.EmitARCStoreStrongCall(addr, null, /*ignored*/ true);
   1308 }
   1309 
   1310 static void emitCXXDestructMethod(CodeGenFunction &CGF,
   1311                                   ObjCImplementationDecl *impl) {
   1312   CodeGenFunction::RunCleanupsScope scope(CGF);
   1313 
   1314   llvm::Value *self = CGF.LoadObjCSelf();
   1315 
   1316   const ObjCInterfaceDecl *iface = impl->getClassInterface();
   1317   for (const ObjCIvarDecl *ivar = iface->all_declared_ivar_begin();
   1318        ivar; ivar = ivar->getNextIvar()) {
   1319     QualType type = ivar->getType();
   1320 
   1321     // Check whether the ivar is a destructible type.
   1322     QualType::DestructionKind dtorKind = type.isDestructedType();
   1323     if (!dtorKind) continue;
   1324 
   1325     CodeGenFunction::Destroyer *destroyer = nullptr;
   1326 
   1327     // Use a call to objc_storeStrong to destroy strong ivars, for the
   1328     // general benefit of the tools.
   1329     if (dtorKind == QualType::DK_objc_strong_lifetime) {
   1330       destroyer = destroyARCStrongWithStore;
   1331 
   1332     // Otherwise use the default for the destruction kind.
   1333     } else {
   1334       destroyer = CGF.getDestroyer(dtorKind);
   1335     }
   1336 
   1337     CleanupKind cleanupKind = CGF.getCleanupKind(dtorKind);
   1338 
   1339     CGF.EHStack.pushCleanup<DestroyIvar>(cleanupKind, self, ivar, destroyer,
   1340                                          cleanupKind & EHCleanup);
   1341   }
   1342 
   1343   assert(scope.requiresCleanups() && "nothing to do in .cxx_destruct?");
   1344 }
   1345 
   1346 void CodeGenFunction::GenerateObjCCtorDtorMethod(ObjCImplementationDecl *IMP,
   1347                                                  ObjCMethodDecl *MD,
   1348                                                  bool ctor) {
   1349   MD->createImplicitParams(CGM.getContext(), IMP->getClassInterface());
   1350   StartObjCMethod(MD, IMP->getClassInterface());
   1351 
   1352   // Emit .cxx_construct.
   1353   if (ctor) {
   1354     // Suppress the final autorelease in ARC.
   1355     AutoreleaseResult = false;
   1356 
   1357     for (const auto *IvarInit : IMP->inits()) {
   1358       FieldDecl *Field = IvarInit->getAnyMember();
   1359       ObjCIvarDecl *Ivar = cast<ObjCIvarDecl>(Field);
   1360       LValue LV = EmitLValueForIvar(TypeOfSelfObject(),
   1361                                     LoadObjCSelf(), Ivar, 0);
   1362       EmitAggExpr(IvarInit->getInit(),
   1363                   AggValueSlot::forLValue(LV, AggValueSlot::IsDestructed,
   1364                                           AggValueSlot::DoesNotNeedGCBarriers,
   1365                                           AggValueSlot::IsNotAliased));
   1366     }
   1367     // constructor returns 'self'.
   1368     CodeGenTypes &Types = CGM.getTypes();
   1369     QualType IdTy(CGM.getContext().getObjCIdType());
   1370     llvm::Value *SelfAsId =
   1371       Builder.CreateBitCast(LoadObjCSelf(), Types.ConvertType(IdTy));
   1372     EmitReturnOfRValue(RValue::get(SelfAsId), IdTy);
   1373 
   1374   // Emit .cxx_destruct.
   1375   } else {
   1376     emitCXXDestructMethod(*this, IMP);
   1377   }
   1378   FinishFunction();
   1379 }
   1380 
   1381 bool CodeGenFunction::IndirectObjCSetterArg(const CGFunctionInfo &FI) {
   1382   CGFunctionInfo::const_arg_iterator it = FI.arg_begin();
   1383   it++; it++;
   1384   const ABIArgInfo &AI = it->info;
   1385   // FIXME. Is this sufficient check?
   1386   return (AI.getKind() == ABIArgInfo::Indirect);
   1387 }
   1388 
   1389 bool CodeGenFunction::IvarTypeWithAggrGCObjects(QualType Ty) {
   1390   if (CGM.getLangOpts().getGC() == LangOptions::NonGC)
   1391     return false;
   1392   if (const RecordType *FDTTy = Ty.getTypePtr()->getAs<RecordType>())
   1393     return FDTTy->getDecl()->hasObjectMember();
   1394   return false;
   1395 }
   1396 
   1397 llvm::Value *CodeGenFunction::LoadObjCSelf() {
   1398   VarDecl *Self = cast<ObjCMethodDecl>(CurFuncDecl)->getSelfDecl();
   1399   DeclRefExpr DRE(Self, /*is enclosing local*/ (CurFuncDecl != CurCodeDecl),
   1400                   Self->getType(), VK_LValue, SourceLocation());
   1401   return EmitLoadOfScalar(EmitDeclRefLValue(&DRE), SourceLocation());
   1402 }
   1403 
   1404 QualType CodeGenFunction::TypeOfSelfObject() {
   1405   const ObjCMethodDecl *OMD = cast<ObjCMethodDecl>(CurFuncDecl);
   1406   ImplicitParamDecl *selfDecl = OMD->getSelfDecl();
   1407   const ObjCObjectPointerType *PTy = cast<ObjCObjectPointerType>(
   1408     getContext().getCanonicalType(selfDecl->getType()));
   1409   return PTy->getPointeeType();
   1410 }
   1411 
   1412 void CodeGenFunction::EmitObjCForCollectionStmt(const ObjCForCollectionStmt &S){
   1413   llvm::Constant *EnumerationMutationFn =
   1414     CGM.getObjCRuntime().EnumerationMutationFunction();
   1415 
   1416   if (!EnumerationMutationFn) {
   1417     CGM.ErrorUnsupported(&S, "Obj-C fast enumeration for this runtime");
   1418     return;
   1419   }
   1420 
   1421   CGDebugInfo *DI = getDebugInfo();
   1422   if (DI)
   1423     DI->EmitLexicalBlockStart(Builder, S.getSourceRange().getBegin());
   1424 
   1425   // The local variable comes into scope immediately.
   1426   AutoVarEmission variable = AutoVarEmission::invalid();
   1427   if (const DeclStmt *SD = dyn_cast<DeclStmt>(S.getElement()))
   1428     variable = EmitAutoVarAlloca(*cast<VarDecl>(SD->getSingleDecl()));
   1429 
   1430   JumpDest LoopEnd = getJumpDestInCurrentScope("forcoll.end");
   1431 
   1432   // Fast enumeration state.
   1433   QualType StateTy = CGM.getObjCFastEnumerationStateType();
   1434   llvm::AllocaInst *StatePtr = CreateMemTemp(StateTy, "state.ptr");
   1435   EmitNullInitialization(StatePtr, StateTy);
   1436 
   1437   // Number of elements in the items array.
   1438   static const unsigned NumItems = 16;
   1439 
   1440   // Fetch the countByEnumeratingWithState:objects:count: selector.
   1441   IdentifierInfo *II[] = {
   1442     &CGM.getContext().Idents.get("countByEnumeratingWithState"),
   1443     &CGM.getContext().Idents.get("objects"),
   1444     &CGM.getContext().Idents.get("count")
   1445   };
   1446   Selector FastEnumSel =
   1447     CGM.getContext().Selectors.getSelector(llvm::array_lengthof(II), &II[0]);
   1448 
   1449   QualType ItemsTy =
   1450     getContext().getConstantArrayType(getContext().getObjCIdType(),
   1451                                       llvm::APInt(32, NumItems),
   1452                                       ArrayType::Normal, 0);
   1453   llvm::Value *ItemsPtr = CreateMemTemp(ItemsTy, "items.ptr");
   1454 
   1455   // Emit the collection pointer.  In ARC, we do a retain.
   1456   llvm::Value *Collection;
   1457   if (getLangOpts().ObjCAutoRefCount) {
   1458     Collection = EmitARCRetainScalarExpr(S.getCollection());
   1459 
   1460     // Enter a cleanup to do the release.
   1461     EmitObjCConsumeObject(S.getCollection()->getType(), Collection);
   1462   } else {
   1463     Collection = EmitScalarExpr(S.getCollection());
   1464   }
   1465 
   1466   // The 'continue' label needs to appear within the cleanup for the
   1467   // collection object.
   1468   JumpDest AfterBody = getJumpDestInCurrentScope("forcoll.next");
   1469 
   1470   // Send it our message:
   1471   CallArgList Args;
   1472 
   1473   // The first argument is a temporary of the enumeration-state type.
   1474   Args.add(RValue::get(StatePtr), getContext().getPointerType(StateTy));
   1475 
   1476   // The second argument is a temporary array with space for NumItems
   1477   // pointers.  We'll actually be loading elements from the array
   1478   // pointer written into the control state; this buffer is so that
   1479   // collections that *aren't* backed by arrays can still queue up
   1480   // batches of elements.
   1481   Args.add(RValue::get(ItemsPtr), getContext().getPointerType(ItemsTy));
   1482 
   1483   // The third argument is the capacity of that temporary array.
   1484   llvm::Type *UnsignedLongLTy = ConvertType(getContext().UnsignedLongTy);
   1485   llvm::Constant *Count = llvm::ConstantInt::get(UnsignedLongLTy, NumItems);
   1486   Args.add(RValue::get(Count), getContext().UnsignedLongTy);
   1487 
   1488   // Start the enumeration.
   1489   RValue CountRV =
   1490     CGM.getObjCRuntime().GenerateMessageSend(*this, ReturnValueSlot(),
   1491                                              getContext().UnsignedLongTy,
   1492                                              FastEnumSel,
   1493                                              Collection, Args);
   1494 
   1495   // The initial number of objects that were returned in the buffer.
   1496   llvm::Value *initialBufferLimit = CountRV.getScalarVal();
   1497 
   1498   llvm::BasicBlock *EmptyBB = createBasicBlock("forcoll.empty");
   1499   llvm::BasicBlock *LoopInitBB = createBasicBlock("forcoll.loopinit");
   1500 
   1501   llvm::Value *zero = llvm::Constant::getNullValue(UnsignedLongLTy);
   1502 
   1503   // If the limit pointer was zero to begin with, the collection is
   1504   // empty; skip all this. Set the branch weight assuming this has the same
   1505   // probability of exiting the loop as any other loop exit.
   1506   uint64_t EntryCount = PGO.getCurrentRegionCount();
   1507   RegionCounter Cnt = getPGORegionCounter(&S);
   1508   Builder.CreateCondBr(Builder.CreateICmpEQ(initialBufferLimit, zero, "iszero"),
   1509                        EmptyBB, LoopInitBB,
   1510                        PGO.createBranchWeights(EntryCount, Cnt.getCount()));
   1511 
   1512   // Otherwise, initialize the loop.
   1513   EmitBlock(LoopInitBB);
   1514 
   1515   // Save the initial mutations value.  This is the value at an
   1516   // address that was written into the state object by
   1517   // countByEnumeratingWithState:objects:count:.
   1518   llvm::Value *StateMutationsPtrPtr = Builder.CreateStructGEP(
   1519       StatePtr->getAllocatedType(), StatePtr, 2, "mutationsptr.ptr");
   1520   llvm::Value *StateMutationsPtr = Builder.CreateLoad(StateMutationsPtrPtr,
   1521                                                       "mutationsptr");
   1522 
   1523   llvm::Value *initialMutations =
   1524     Builder.CreateLoad(StateMutationsPtr, "forcoll.initial-mutations");
   1525 
   1526   // Start looping.  This is the point we return to whenever we have a
   1527   // fresh, non-empty batch of objects.
   1528   llvm::BasicBlock *LoopBodyBB = createBasicBlock("forcoll.loopbody");
   1529   EmitBlock(LoopBodyBB);
   1530 
   1531   // The current index into the buffer.
   1532   llvm::PHINode *index = Builder.CreatePHI(UnsignedLongLTy, 3, "forcoll.index");
   1533   index->addIncoming(zero, LoopInitBB);
   1534 
   1535   // The current buffer size.
   1536   llvm::PHINode *count = Builder.CreatePHI(UnsignedLongLTy, 3, "forcoll.count");
   1537   count->addIncoming(initialBufferLimit, LoopInitBB);
   1538 
   1539   Cnt.beginRegion(Builder);
   1540 
   1541   // Check whether the mutations value has changed from where it was
   1542   // at start.  StateMutationsPtr should actually be invariant between
   1543   // refreshes.
   1544   StateMutationsPtr = Builder.CreateLoad(StateMutationsPtrPtr, "mutationsptr");
   1545   llvm::Value *currentMutations
   1546     = Builder.CreateLoad(StateMutationsPtr, "statemutations");
   1547 
   1548   llvm::BasicBlock *WasMutatedBB = createBasicBlock("forcoll.mutated");
   1549   llvm::BasicBlock *WasNotMutatedBB = createBasicBlock("forcoll.notmutated");
   1550 
   1551   Builder.CreateCondBr(Builder.CreateICmpEQ(currentMutations, initialMutations),
   1552                        WasNotMutatedBB, WasMutatedBB);
   1553 
   1554   // If so, call the enumeration-mutation function.
   1555   EmitBlock(WasMutatedBB);
   1556   llvm::Value *V =
   1557     Builder.CreateBitCast(Collection,
   1558                           ConvertType(getContext().getObjCIdType()));
   1559   CallArgList Args2;
   1560   Args2.add(RValue::get(V), getContext().getObjCIdType());
   1561   // FIXME: We shouldn't need to get the function info here, the runtime already
   1562   // should have computed it to build the function.
   1563   EmitCall(CGM.getTypes().arrangeFreeFunctionCall(getContext().VoidTy, Args2,
   1564                                                   FunctionType::ExtInfo(),
   1565                                                   RequiredArgs::All),
   1566            EnumerationMutationFn, ReturnValueSlot(), Args2);
   1567 
   1568   // Otherwise, or if the mutation function returns, just continue.
   1569   EmitBlock(WasNotMutatedBB);
   1570 
   1571   // Initialize the element variable.
   1572   RunCleanupsScope elementVariableScope(*this);
   1573   bool elementIsVariable;
   1574   LValue elementLValue;
   1575   QualType elementType;
   1576   if (const DeclStmt *SD = dyn_cast<DeclStmt>(S.getElement())) {
   1577     // Initialize the variable, in case it's a __block variable or something.
   1578     EmitAutoVarInit(variable);
   1579 
   1580     const VarDecl* D = cast<VarDecl>(SD->getSingleDecl());
   1581     DeclRefExpr tempDRE(const_cast<VarDecl*>(D), false, D->getType(),
   1582                         VK_LValue, SourceLocation());
   1583     elementLValue = EmitLValue(&tempDRE);
   1584     elementType = D->getType();
   1585     elementIsVariable = true;
   1586 
   1587     if (D->isARCPseudoStrong())
   1588       elementLValue.getQuals().setObjCLifetime(Qualifiers::OCL_ExplicitNone);
   1589   } else {
   1590     elementLValue = LValue(); // suppress warning
   1591     elementType = cast<Expr>(S.getElement())->getType();
   1592     elementIsVariable = false;
   1593   }
   1594   llvm::Type *convertedElementType = ConvertType(elementType);
   1595 
   1596   // Fetch the buffer out of the enumeration state.
   1597   // TODO: this pointer should actually be invariant between
   1598   // refreshes, which would help us do certain loop optimizations.
   1599   llvm::Value *StateItemsPtr = Builder.CreateStructGEP(
   1600       StatePtr->getAllocatedType(), StatePtr, 1, "stateitems.ptr");
   1601   llvm::Value *EnumStateItems =
   1602     Builder.CreateLoad(StateItemsPtr, "stateitems");
   1603 
   1604   // Fetch the value at the current index from the buffer.
   1605   llvm::Value *CurrentItemPtr =
   1606     Builder.CreateGEP(EnumStateItems, index, "currentitem.ptr");
   1607   llvm::Value *CurrentItem = Builder.CreateLoad(CurrentItemPtr);
   1608 
   1609   // Cast that value to the right type.
   1610   CurrentItem = Builder.CreateBitCast(CurrentItem, convertedElementType,
   1611                                       "currentitem");
   1612 
   1613   // Make sure we have an l-value.  Yes, this gets evaluated every
   1614   // time through the loop.
   1615   if (!elementIsVariable) {
   1616     elementLValue = EmitLValue(cast<Expr>(S.getElement()));
   1617     EmitStoreThroughLValue(RValue::get(CurrentItem), elementLValue);
   1618   } else {
   1619     EmitScalarInit(CurrentItem, elementLValue);
   1620   }
   1621 
   1622   // If we do have an element variable, this assignment is the end of
   1623   // its initialization.
   1624   if (elementIsVariable)
   1625     EmitAutoVarCleanups(variable);
   1626 
   1627   // Perform the loop body, setting up break and continue labels.
   1628   BreakContinueStack.push_back(BreakContinue(LoopEnd, AfterBody));
   1629   {
   1630     RunCleanupsScope Scope(*this);
   1631     EmitStmt(S.getBody());
   1632   }
   1633   BreakContinueStack.pop_back();
   1634 
   1635   // Destroy the element variable now.
   1636   elementVariableScope.ForceCleanup();
   1637 
   1638   // Check whether there are more elements.
   1639   EmitBlock(AfterBody.getBlock());
   1640 
   1641   llvm::BasicBlock *FetchMoreBB = createBasicBlock("forcoll.refetch");
   1642 
   1643   // First we check in the local buffer.
   1644   llvm::Value *indexPlusOne
   1645     = Builder.CreateAdd(index, llvm::ConstantInt::get(UnsignedLongLTy, 1));
   1646 
   1647   // If we haven't overrun the buffer yet, we can continue.
   1648   // Set the branch weights based on the simplifying assumption that this is
   1649   // like a while-loop, i.e., ignoring that the false branch fetches more
   1650   // elements and then returns to the loop.
   1651   Builder.CreateCondBr(Builder.CreateICmpULT(indexPlusOne, count),
   1652                        LoopBodyBB, FetchMoreBB,
   1653                        PGO.createBranchWeights(Cnt.getCount(), EntryCount));
   1654 
   1655   index->addIncoming(indexPlusOne, AfterBody.getBlock());
   1656   count->addIncoming(count, AfterBody.getBlock());
   1657 
   1658   // Otherwise, we have to fetch more elements.
   1659   EmitBlock(FetchMoreBB);
   1660 
   1661   CountRV =
   1662     CGM.getObjCRuntime().GenerateMessageSend(*this, ReturnValueSlot(),
   1663                                              getContext().UnsignedLongTy,
   1664                                              FastEnumSel,
   1665                                              Collection, Args);
   1666 
   1667   // If we got a zero count, we're done.
   1668   llvm::Value *refetchCount = CountRV.getScalarVal();
   1669 
   1670   // (note that the message send might split FetchMoreBB)
   1671   index->addIncoming(zero, Builder.GetInsertBlock());
   1672   count->addIncoming(refetchCount, Builder.GetInsertBlock());
   1673 
   1674   Builder.CreateCondBr(Builder.CreateICmpEQ(refetchCount, zero),
   1675                        EmptyBB, LoopBodyBB);
   1676 
   1677   // No more elements.
   1678   EmitBlock(EmptyBB);
   1679 
   1680   if (!elementIsVariable) {
   1681     // If the element was not a declaration, set it to be null.
   1682 
   1683     llvm::Value *null = llvm::Constant::getNullValue(convertedElementType);
   1684     elementLValue = EmitLValue(cast<Expr>(S.getElement()));
   1685     EmitStoreThroughLValue(RValue::get(null), elementLValue);
   1686   }
   1687 
   1688   if (DI)
   1689     DI->EmitLexicalBlockEnd(Builder, S.getSourceRange().getEnd());
   1690 
   1691   // Leave the cleanup we entered in ARC.
   1692   if (getLangOpts().ObjCAutoRefCount)
   1693     PopCleanupBlock();
   1694 
   1695   EmitBlock(LoopEnd.getBlock());
   1696 }
   1697 
   1698 void CodeGenFunction::EmitObjCAtTryStmt(const ObjCAtTryStmt &S) {
   1699   CGM.getObjCRuntime().EmitTryStmt(*this, S);
   1700 }
   1701 
   1702 void CodeGenFunction::EmitObjCAtThrowStmt(const ObjCAtThrowStmt &S) {
   1703   CGM.getObjCRuntime().EmitThrowStmt(*this, S);
   1704 }
   1705 
   1706 void CodeGenFunction::EmitObjCAtSynchronizedStmt(
   1707                                               const ObjCAtSynchronizedStmt &S) {
   1708   CGM.getObjCRuntime().EmitSynchronizedStmt(*this, S);
   1709 }
   1710 
   1711 /// Produce the code for a CK_ARCProduceObject.  Just does a
   1712 /// primitive retain.
   1713 llvm::Value *CodeGenFunction::EmitObjCProduceObject(QualType type,
   1714                                                     llvm::Value *value) {
   1715   return EmitARCRetain(type, value);
   1716 }
   1717 
   1718 namespace {
   1719   struct CallObjCRelease : EHScopeStack::Cleanup {
   1720     CallObjCRelease(llvm::Value *object) : object(object) {}
   1721     llvm::Value *object;
   1722 
   1723     void Emit(CodeGenFunction &CGF, Flags flags) override {
   1724       // Releases at the end of the full-expression are imprecise.
   1725       CGF.EmitARCRelease(object, ARCImpreciseLifetime);
   1726     }
   1727   };
   1728 }
   1729 
   1730 /// Produce the code for a CK_ARCConsumeObject.  Does a primitive
   1731 /// release at the end of the full-expression.
   1732 llvm::Value *CodeGenFunction::EmitObjCConsumeObject(QualType type,
   1733                                                     llvm::Value *object) {
   1734   // If we're in a conditional branch, we need to make the cleanup
   1735   // conditional.
   1736   pushFullExprCleanup<CallObjCRelease>(getARCCleanupKind(), object);
   1737   return object;
   1738 }
   1739 
   1740 llvm::Value *CodeGenFunction::EmitObjCExtendObjectLifetime(QualType type,
   1741                                                            llvm::Value *value) {
   1742   return EmitARCRetainAutorelease(type, value);
   1743 }
   1744 
   1745 /// Given a number of pointers, inform the optimizer that they're
   1746 /// being intrinsically used up until this point in the program.
   1747 void CodeGenFunction::EmitARCIntrinsicUse(ArrayRef<llvm::Value*> values) {
   1748   llvm::Constant *&fn = CGM.getARCEntrypoints().clang_arc_use;
   1749   if (!fn) {
   1750     llvm::FunctionType *fnType =
   1751       llvm::FunctionType::get(CGM.VoidTy, None, true);
   1752     fn = CGM.CreateRuntimeFunction(fnType, "clang.arc.use");
   1753   }
   1754 
   1755   // This isn't really a "runtime" function, but as an intrinsic it
   1756   // doesn't really matter as long as we align things up.
   1757   EmitNounwindRuntimeCall(fn, values);
   1758 }
   1759 
   1760 
   1761 static llvm::Constant *createARCRuntimeFunction(CodeGenModule &CGM,
   1762                                                 llvm::FunctionType *type,
   1763                                                 StringRef fnName) {
   1764   llvm::Constant *fn = CGM.CreateRuntimeFunction(type, fnName);
   1765 
   1766   if (llvm::Function *f = dyn_cast<llvm::Function>(fn)) {
   1767     // If the target runtime doesn't naturally support ARC, emit weak
   1768     // references to the runtime support library.  We don't really
   1769     // permit this to fail, but we need a particular relocation style.
   1770     if (!CGM.getLangOpts().ObjCRuntime.hasNativeARC()) {
   1771       f->setLinkage(llvm::Function::ExternalWeakLinkage);
   1772     } else if (fnName == "objc_retain" || fnName  == "objc_release") {
   1773       // If we have Native ARC, set nonlazybind attribute for these APIs for
   1774       // performance.
   1775       f->addFnAttr(llvm::Attribute::NonLazyBind);
   1776     }
   1777   }
   1778 
   1779   return fn;
   1780 }
   1781 
   1782 /// Perform an operation having the signature
   1783 ///   i8* (i8*)
   1784 /// where a null input causes a no-op and returns null.
   1785 static llvm::Value *emitARCValueOperation(CodeGenFunction &CGF,
   1786                                           llvm::Value *value,
   1787                                           llvm::Constant *&fn,
   1788                                           StringRef fnName,
   1789                                           bool isTailCall = false) {
   1790   if (isa<llvm::ConstantPointerNull>(value)) return value;
   1791 
   1792   if (!fn) {
   1793     llvm::FunctionType *fnType =
   1794       llvm::FunctionType::get(CGF.Int8PtrTy, CGF.Int8PtrTy, false);
   1795     fn = createARCRuntimeFunction(CGF.CGM, fnType, fnName);
   1796   }
   1797 
   1798   // Cast the argument to 'id'.
   1799   llvm::Type *origType = value->getType();
   1800   value = CGF.Builder.CreateBitCast(value, CGF.Int8PtrTy);
   1801 
   1802   // Call the function.
   1803   llvm::CallInst *call = CGF.EmitNounwindRuntimeCall(fn, value);
   1804   if (isTailCall)
   1805     call->setTailCall();
   1806 
   1807   // Cast the result back to the original type.
   1808   return CGF.Builder.CreateBitCast(call, origType);
   1809 }
   1810 
   1811 /// Perform an operation having the following signature:
   1812 ///   i8* (i8**)
   1813 static llvm::Value *emitARCLoadOperation(CodeGenFunction &CGF,
   1814                                          llvm::Value *addr,
   1815                                          llvm::Constant *&fn,
   1816                                          StringRef fnName) {
   1817   if (!fn) {
   1818     llvm::FunctionType *fnType =
   1819       llvm::FunctionType::get(CGF.Int8PtrTy, CGF.Int8PtrPtrTy, false);
   1820     fn = createARCRuntimeFunction(CGF.CGM, fnType, fnName);
   1821   }
   1822 
   1823   // Cast the argument to 'id*'.
   1824   llvm::Type *origType = addr->getType();
   1825   addr = CGF.Builder.CreateBitCast(addr, CGF.Int8PtrPtrTy);
   1826 
   1827   // Call the function.
   1828   llvm::Value *result = CGF.EmitNounwindRuntimeCall(fn, addr);
   1829 
   1830   // Cast the result back to a dereference of the original type.
   1831   if (origType != CGF.Int8PtrPtrTy)
   1832     result = CGF.Builder.CreateBitCast(result,
   1833                         cast<llvm::PointerType>(origType)->getElementType());
   1834 
   1835   return result;
   1836 }
   1837 
   1838 /// Perform an operation having the following signature:
   1839 ///   i8* (i8**, i8*)
   1840 static llvm::Value *emitARCStoreOperation(CodeGenFunction &CGF,
   1841                                           llvm::Value *addr,
   1842                                           llvm::Value *value,
   1843                                           llvm::Constant *&fn,
   1844                                           StringRef fnName,
   1845                                           bool ignored) {
   1846   assert(cast<llvm::PointerType>(addr->getType())->getElementType()
   1847            == value->getType());
   1848 
   1849   if (!fn) {
   1850     llvm::Type *argTypes[] = { CGF.Int8PtrPtrTy, CGF.Int8PtrTy };
   1851 
   1852     llvm::FunctionType *fnType
   1853       = llvm::FunctionType::get(CGF.Int8PtrTy, argTypes, false);
   1854     fn = createARCRuntimeFunction(CGF.CGM, fnType, fnName);
   1855   }
   1856 
   1857   llvm::Type *origType = value->getType();
   1858 
   1859   llvm::Value *args[] = {
   1860     CGF.Builder.CreateBitCast(addr, CGF.Int8PtrPtrTy),
   1861     CGF.Builder.CreateBitCast(value, CGF.Int8PtrTy)
   1862   };
   1863   llvm::CallInst *result = CGF.EmitNounwindRuntimeCall(fn, args);
   1864 
   1865   if (ignored) return nullptr;
   1866 
   1867   return CGF.Builder.CreateBitCast(result, origType);
   1868 }
   1869 
   1870 /// Perform an operation having the following signature:
   1871 ///   void (i8**, i8**)
   1872 static void emitARCCopyOperation(CodeGenFunction &CGF,
   1873                                  llvm::Value *dst,
   1874                                  llvm::Value *src,
   1875                                  llvm::Constant *&fn,
   1876                                  StringRef fnName) {
   1877   assert(dst->getType() == src->getType());
   1878 
   1879   if (!fn) {
   1880     llvm::Type *argTypes[] = { CGF.Int8PtrPtrTy, CGF.Int8PtrPtrTy };
   1881 
   1882     llvm::FunctionType *fnType
   1883       = llvm::FunctionType::get(CGF.Builder.getVoidTy(), argTypes, false);
   1884     fn = createARCRuntimeFunction(CGF.CGM, fnType, fnName);
   1885   }
   1886 
   1887   llvm::Value *args[] = {
   1888     CGF.Builder.CreateBitCast(dst, CGF.Int8PtrPtrTy),
   1889     CGF.Builder.CreateBitCast(src, CGF.Int8PtrPtrTy)
   1890   };
   1891   CGF.EmitNounwindRuntimeCall(fn, args);
   1892 }
   1893 
   1894 /// Produce the code to do a retain.  Based on the type, calls one of:
   1895 ///   call i8* \@objc_retain(i8* %value)
   1896 ///   call i8* \@objc_retainBlock(i8* %value)
   1897 llvm::Value *CodeGenFunction::EmitARCRetain(QualType type, llvm::Value *value) {
   1898   if (type->isBlockPointerType())
   1899     return EmitARCRetainBlock(value, /*mandatory*/ false);
   1900   else
   1901     return EmitARCRetainNonBlock(value);
   1902 }
   1903 
   1904 /// Retain the given object, with normal retain semantics.
   1905 ///   call i8* \@objc_retain(i8* %value)
   1906 llvm::Value *CodeGenFunction::EmitARCRetainNonBlock(llvm::Value *value) {
   1907   return emitARCValueOperation(*this, value,
   1908                                CGM.getARCEntrypoints().objc_retain,
   1909                                "objc_retain");
   1910 }
   1911 
   1912 /// Retain the given block, with _Block_copy semantics.
   1913 ///   call i8* \@objc_retainBlock(i8* %value)
   1914 ///
   1915 /// \param mandatory - If false, emit the call with metadata
   1916 /// indicating that it's okay for the optimizer to eliminate this call
   1917 /// if it can prove that the block never escapes except down the stack.
   1918 llvm::Value *CodeGenFunction::EmitARCRetainBlock(llvm::Value *value,
   1919                                                  bool mandatory) {
   1920   llvm::Value *result
   1921     = emitARCValueOperation(*this, value,
   1922                             CGM.getARCEntrypoints().objc_retainBlock,
   1923                             "objc_retainBlock");
   1924 
   1925   // If the copy isn't mandatory, add !clang.arc.copy_on_escape to
   1926   // tell the optimizer that it doesn't need to do this copy if the
   1927   // block doesn't escape, where being passed as an argument doesn't
   1928   // count as escaping.
   1929   if (!mandatory && isa<llvm::Instruction>(result)) {
   1930     llvm::CallInst *call
   1931       = cast<llvm::CallInst>(result->stripPointerCasts());
   1932     assert(call->getCalledValue() == CGM.getARCEntrypoints().objc_retainBlock);
   1933 
   1934     call->setMetadata("clang.arc.copy_on_escape",
   1935                       llvm::MDNode::get(Builder.getContext(), None));
   1936   }
   1937 
   1938   return result;
   1939 }
   1940 
   1941 /// Retain the given object which is the result of a function call.
   1942 ///   call i8* \@objc_retainAutoreleasedReturnValue(i8* %value)
   1943 ///
   1944 /// Yes, this function name is one character away from a different
   1945 /// call with completely different semantics.
   1946 llvm::Value *
   1947 CodeGenFunction::EmitARCRetainAutoreleasedReturnValue(llvm::Value *value) {
   1948   // Fetch the void(void) inline asm which marks that we're going to
   1949   // retain the autoreleased return value.
   1950   llvm::InlineAsm *&marker
   1951     = CGM.getARCEntrypoints().retainAutoreleasedReturnValueMarker;
   1952   if (!marker) {
   1953     StringRef assembly
   1954       = CGM.getTargetCodeGenInfo()
   1955            .getARCRetainAutoreleasedReturnValueMarker();
   1956 
   1957     // If we have an empty assembly string, there's nothing to do.
   1958     if (assembly.empty()) {
   1959 
   1960     // Otherwise, at -O0, build an inline asm that we're going to call
   1961     // in a moment.
   1962     } else if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
   1963       llvm::FunctionType *type =
   1964         llvm::FunctionType::get(VoidTy, /*variadic*/false);
   1965 
   1966       marker = llvm::InlineAsm::get(type, assembly, "", /*sideeffects*/ true);
   1967 
   1968     // If we're at -O1 and above, we don't want to litter the code
   1969     // with this marker yet, so leave a breadcrumb for the ARC
   1970     // optimizer to pick up.
   1971     } else {
   1972       llvm::NamedMDNode *metadata =
   1973         CGM.getModule().getOrInsertNamedMetadata(
   1974                             "clang.arc.retainAutoreleasedReturnValueMarker");
   1975       assert(metadata->getNumOperands() <= 1);
   1976       if (metadata->getNumOperands() == 0) {
   1977         metadata->addOperand(llvm::MDNode::get(
   1978             getLLVMContext(), llvm::MDString::get(getLLVMContext(), assembly)));
   1979       }
   1980     }
   1981   }
   1982 
   1983   // Call the marker asm if we made one, which we do only at -O0.
   1984   if (marker) Builder.CreateCall(marker);
   1985 
   1986   return emitARCValueOperation(*this, value,
   1987                      CGM.getARCEntrypoints().objc_retainAutoreleasedReturnValue,
   1988                                "objc_retainAutoreleasedReturnValue");
   1989 }
   1990 
   1991 /// Release the given object.
   1992 ///   call void \@objc_release(i8* %value)
   1993 void CodeGenFunction::EmitARCRelease(llvm::Value *value,
   1994                                      ARCPreciseLifetime_t precise) {
   1995   if (isa<llvm::ConstantPointerNull>(value)) return;
   1996 
   1997   llvm::Constant *&fn = CGM.getARCEntrypoints().objc_release;
   1998   if (!fn) {
   1999     llvm::FunctionType *fnType =
   2000       llvm::FunctionType::get(Builder.getVoidTy(), Int8PtrTy, false);
   2001     fn = createARCRuntimeFunction(CGM, fnType, "objc_release");
   2002   }
   2003 
   2004   // Cast the argument to 'id'.
   2005   value = Builder.CreateBitCast(value, Int8PtrTy);
   2006 
   2007   // Call objc_release.
   2008   llvm::CallInst *call = EmitNounwindRuntimeCall(fn, value);
   2009 
   2010   if (precise == ARCImpreciseLifetime) {
   2011     call->setMetadata("clang.imprecise_release",
   2012                       llvm::MDNode::get(Builder.getContext(), None));
   2013   }
   2014 }
   2015 
   2016 /// Destroy a __strong variable.
   2017 ///
   2018 /// At -O0, emit a call to store 'null' into the address;
   2019 /// instrumenting tools prefer this because the address is exposed,
   2020 /// but it's relatively cumbersome to optimize.
   2021 ///
   2022 /// At -O1 and above, just load and call objc_release.
   2023 ///
   2024 ///   call void \@objc_storeStrong(i8** %addr, i8* null)
   2025 void CodeGenFunction::EmitARCDestroyStrong(llvm::Value *addr,
   2026                                            ARCPreciseLifetime_t precise) {
   2027   if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
   2028     llvm::PointerType *addrTy = cast<llvm::PointerType>(addr->getType());
   2029     llvm::Value *null = llvm::ConstantPointerNull::get(
   2030                           cast<llvm::PointerType>(addrTy->getElementType()));
   2031     EmitARCStoreStrongCall(addr, null, /*ignored*/ true);
   2032     return;
   2033   }
   2034 
   2035   llvm::Value *value = Builder.CreateLoad(addr);
   2036   EmitARCRelease(value, precise);
   2037 }
   2038 
   2039 /// Store into a strong object.  Always calls this:
   2040 ///   call void \@objc_storeStrong(i8** %addr, i8* %value)
   2041 llvm::Value *CodeGenFunction::EmitARCStoreStrongCall(llvm::Value *addr,
   2042                                                      llvm::Value *value,
   2043                                                      bool ignored) {
   2044   assert(cast<llvm::PointerType>(addr->getType())->getElementType()
   2045            == value->getType());
   2046 
   2047   llvm::Constant *&fn = CGM.getARCEntrypoints().objc_storeStrong;
   2048   if (!fn) {
   2049     llvm::Type *argTypes[] = { Int8PtrPtrTy, Int8PtrTy };
   2050     llvm::FunctionType *fnType
   2051       = llvm::FunctionType::get(Builder.getVoidTy(), argTypes, false);
   2052     fn = createARCRuntimeFunction(CGM, fnType, "objc_storeStrong");
   2053   }
   2054 
   2055   llvm::Value *args[] = {
   2056     Builder.CreateBitCast(addr, Int8PtrPtrTy),
   2057     Builder.CreateBitCast(value, Int8PtrTy)
   2058   };
   2059   EmitNounwindRuntimeCall(fn, args);
   2060 
   2061   if (ignored) return nullptr;
   2062   return value;
   2063 }
   2064 
   2065 /// Store into a strong object.  Sometimes calls this:
   2066 ///   call void \@objc_storeStrong(i8** %addr, i8* %value)
   2067 /// Other times, breaks it down into components.
   2068 llvm::Value *CodeGenFunction::EmitARCStoreStrong(LValue dst,
   2069                                                  llvm::Value *newValue,
   2070                                                  bool ignored) {
   2071   QualType type = dst.getType();
   2072   bool isBlock = type->isBlockPointerType();
   2073 
   2074   // Use a store barrier at -O0 unless this is a block type or the
   2075   // lvalue is inadequately aligned.
   2076   if (shouldUseFusedARCCalls() &&
   2077       !isBlock &&
   2078       (dst.getAlignment().isZero() ||
   2079        dst.getAlignment() >= CharUnits::fromQuantity(PointerAlignInBytes))) {
   2080     return EmitARCStoreStrongCall(dst.getAddress(), newValue, ignored);
   2081   }
   2082 
   2083   // Otherwise, split it out.
   2084 
   2085   // Retain the new value.
   2086   newValue = EmitARCRetain(type, newValue);
   2087 
   2088   // Read the old value.
   2089   llvm::Value *oldValue = EmitLoadOfScalar(dst, SourceLocation());
   2090 
   2091   // Store.  We do this before the release so that any deallocs won't
   2092   // see the old value.
   2093   EmitStoreOfScalar(newValue, dst);
   2094 
   2095   // Finally, release the old value.
   2096   EmitARCRelease(oldValue, dst.isARCPreciseLifetime());
   2097 
   2098   return newValue;
   2099 }
   2100 
   2101 /// Autorelease the given object.
   2102 ///   call i8* \@objc_autorelease(i8* %value)
   2103 llvm::Value *CodeGenFunction::EmitARCAutorelease(llvm::Value *value) {
   2104   return emitARCValueOperation(*this, value,
   2105                                CGM.getARCEntrypoints().objc_autorelease,
   2106                                "objc_autorelease");
   2107 }
   2108 
   2109 /// Autorelease the given object.
   2110 ///   call i8* \@objc_autoreleaseReturnValue(i8* %value)
   2111 llvm::Value *
   2112 CodeGenFunction::EmitARCAutoreleaseReturnValue(llvm::Value *value) {
   2113   return emitARCValueOperation(*this, value,
   2114                             CGM.getARCEntrypoints().objc_autoreleaseReturnValue,
   2115                                "objc_autoreleaseReturnValue",
   2116                                /*isTailCall*/ true);
   2117 }
   2118 
   2119 /// Do a fused retain/autorelease of the given object.
   2120 ///   call i8* \@objc_retainAutoreleaseReturnValue(i8* %value)
   2121 llvm::Value *
   2122 CodeGenFunction::EmitARCRetainAutoreleaseReturnValue(llvm::Value *value) {
   2123   return emitARCValueOperation(*this, value,
   2124                      CGM.getARCEntrypoints().objc_retainAutoreleaseReturnValue,
   2125                                "objc_retainAutoreleaseReturnValue",
   2126                                /*isTailCall*/ true);
   2127 }
   2128 
   2129 /// Do a fused retain/autorelease of the given object.
   2130 ///   call i8* \@objc_retainAutorelease(i8* %value)
   2131 /// or
   2132 ///   %retain = call i8* \@objc_retainBlock(i8* %value)
   2133 ///   call i8* \@objc_autorelease(i8* %retain)
   2134 llvm::Value *CodeGenFunction::EmitARCRetainAutorelease(QualType type,
   2135                                                        llvm::Value *value) {
   2136   if (!type->isBlockPointerType())
   2137     return EmitARCRetainAutoreleaseNonBlock(value);
   2138 
   2139   if (isa<llvm::ConstantPointerNull>(value)) return value;
   2140 
   2141   llvm::Type *origType = value->getType();
   2142   value = Builder.CreateBitCast(value, Int8PtrTy);
   2143   value = EmitARCRetainBlock(value, /*mandatory*/ true);
   2144   value = EmitARCAutorelease(value);
   2145   return Builder.CreateBitCast(value, origType);
   2146 }
   2147 
   2148 /// Do a fused retain/autorelease of the given object.
   2149 ///   call i8* \@objc_retainAutorelease(i8* %value)
   2150 llvm::Value *
   2151 CodeGenFunction::EmitARCRetainAutoreleaseNonBlock(llvm::Value *value) {
   2152   return emitARCValueOperation(*this, value,
   2153                                CGM.getARCEntrypoints().objc_retainAutorelease,
   2154                                "objc_retainAutorelease");
   2155 }
   2156 
   2157 /// i8* \@objc_loadWeak(i8** %addr)
   2158 /// Essentially objc_autorelease(objc_loadWeakRetained(addr)).
   2159 llvm::Value *CodeGenFunction::EmitARCLoadWeak(llvm::Value *addr) {
   2160   return emitARCLoadOperation(*this, addr,
   2161                               CGM.getARCEntrypoints().objc_loadWeak,
   2162                               "objc_loadWeak");
   2163 }
   2164 
   2165 /// i8* \@objc_loadWeakRetained(i8** %addr)
   2166 llvm::Value *CodeGenFunction::EmitARCLoadWeakRetained(llvm::Value *addr) {
   2167   return emitARCLoadOperation(*this, addr,
   2168                               CGM.getARCEntrypoints().objc_loadWeakRetained,
   2169                               "objc_loadWeakRetained");
   2170 }
   2171 
   2172 /// i8* \@objc_storeWeak(i8** %addr, i8* %value)
   2173 /// Returns %value.
   2174 llvm::Value *CodeGenFunction::EmitARCStoreWeak(llvm::Value *addr,
   2175                                                llvm::Value *value,
   2176                                                bool ignored) {
   2177   return emitARCStoreOperation(*this, addr, value,
   2178                                CGM.getARCEntrypoints().objc_storeWeak,
   2179                                "objc_storeWeak", ignored);
   2180 }
   2181 
   2182 /// i8* \@objc_initWeak(i8** %addr, i8* %value)
   2183 /// Returns %value.  %addr is known to not have a current weak entry.
   2184 /// Essentially equivalent to:
   2185 ///   *addr = nil; objc_storeWeak(addr, value);
   2186 void CodeGenFunction::EmitARCInitWeak(llvm::Value *addr, llvm::Value *value) {
   2187   // If we're initializing to null, just write null to memory; no need
   2188   // to get the runtime involved.  But don't do this if optimization
   2189   // is enabled, because accounting for this would make the optimizer
   2190   // much more complicated.
   2191   if (isa<llvm::ConstantPointerNull>(value) &&
   2192       CGM.getCodeGenOpts().OptimizationLevel == 0) {
   2193     Builder.CreateStore(value, addr);
   2194     return;
   2195   }
   2196 
   2197   emitARCStoreOperation(*this, addr, value,
   2198                         CGM.getARCEntrypoints().objc_initWeak,
   2199                         "objc_initWeak", /*ignored*/ true);
   2200 }
   2201 
   2202 /// void \@objc_destroyWeak(i8** %addr)
   2203 /// Essentially objc_storeWeak(addr, nil).
   2204 void CodeGenFunction::EmitARCDestroyWeak(llvm::Value *addr) {
   2205   llvm::Constant *&fn = CGM.getARCEntrypoints().objc_destroyWeak;
   2206   if (!fn) {
   2207     llvm::FunctionType *fnType =
   2208       llvm::FunctionType::get(Builder.getVoidTy(), Int8PtrPtrTy, false);
   2209     fn = createARCRuntimeFunction(CGM, fnType, "objc_destroyWeak");
   2210   }
   2211 
   2212   // Cast the argument to 'id*'.
   2213   addr = Builder.CreateBitCast(addr, Int8PtrPtrTy);
   2214 
   2215   EmitNounwindRuntimeCall(fn, addr);
   2216 }
   2217 
   2218 /// void \@objc_moveWeak(i8** %dest, i8** %src)
   2219 /// Disregards the current value in %dest.  Leaves %src pointing to nothing.
   2220 /// Essentially (objc_copyWeak(dest, src), objc_destroyWeak(src)).
   2221 void CodeGenFunction::EmitARCMoveWeak(llvm::Value *dst, llvm::Value *src) {
   2222   emitARCCopyOperation(*this, dst, src,
   2223                        CGM.getARCEntrypoints().objc_moveWeak,
   2224                        "objc_moveWeak");
   2225 }
   2226 
   2227 /// void \@objc_copyWeak(i8** %dest, i8** %src)
   2228 /// Disregards the current value in %dest.  Essentially
   2229 ///   objc_release(objc_initWeak(dest, objc_readWeakRetained(src)))
   2230 void CodeGenFunction::EmitARCCopyWeak(llvm::Value *dst, llvm::Value *src) {
   2231   emitARCCopyOperation(*this, dst, src,
   2232                        CGM.getARCEntrypoints().objc_copyWeak,
   2233                        "objc_copyWeak");
   2234 }
   2235 
   2236 /// Produce the code to do a objc_autoreleasepool_push.
   2237 ///   call i8* \@objc_autoreleasePoolPush(void)
   2238 llvm::Value *CodeGenFunction::EmitObjCAutoreleasePoolPush() {
   2239   llvm::Constant *&fn = CGM.getRREntrypoints().objc_autoreleasePoolPush;
   2240   if (!fn) {
   2241     llvm::FunctionType *fnType =
   2242       llvm::FunctionType::get(Int8PtrTy, false);
   2243     fn = createARCRuntimeFunction(CGM, fnType, "objc_autoreleasePoolPush");
   2244   }
   2245 
   2246   return EmitNounwindRuntimeCall(fn);
   2247 }
   2248 
   2249 /// Produce the code to do a primitive release.
   2250 ///   call void \@objc_autoreleasePoolPop(i8* %ptr)
   2251 void CodeGenFunction::EmitObjCAutoreleasePoolPop(llvm::Value *value) {
   2252   assert(value->getType() == Int8PtrTy);
   2253 
   2254   llvm::Constant *&fn = CGM.getRREntrypoints().objc_autoreleasePoolPop;
   2255   if (!fn) {
   2256     llvm::FunctionType *fnType =
   2257       llvm::FunctionType::get(Builder.getVoidTy(), Int8PtrTy, false);
   2258 
   2259     // We don't want to use a weak import here; instead we should not
   2260     // fall into this path.
   2261     fn = createARCRuntimeFunction(CGM, fnType, "objc_autoreleasePoolPop");
   2262   }
   2263 
   2264   // objc_autoreleasePoolPop can throw.
   2265   EmitRuntimeCallOrInvoke(fn, value);
   2266 }
   2267 
   2268 /// Produce the code to do an MRR version objc_autoreleasepool_push.
   2269 /// Which is: [[NSAutoreleasePool alloc] init];
   2270 /// Where alloc is declared as: + (id) alloc; in NSAutoreleasePool class.
   2271 /// init is declared as: - (id) init; in its NSObject super class.
   2272 ///
   2273 llvm::Value *CodeGenFunction::EmitObjCMRRAutoreleasePoolPush() {
   2274   CGObjCRuntime &Runtime = CGM.getObjCRuntime();
   2275   llvm::Value *Receiver = Runtime.EmitNSAutoreleasePoolClassRef(*this);
   2276   // [NSAutoreleasePool alloc]
   2277   IdentifierInfo *II = &CGM.getContext().Idents.get("alloc");
   2278   Selector AllocSel = getContext().Selectors.getSelector(0, &II);
   2279   CallArgList Args;
   2280   RValue AllocRV =
   2281     Runtime.GenerateMessageSend(*this, ReturnValueSlot(),
   2282                                 getContext().getObjCIdType(),
   2283                                 AllocSel, Receiver, Args);
   2284 
   2285   // [Receiver init]
   2286   Receiver = AllocRV.getScalarVal();
   2287   II = &CGM.getContext().Idents.get("init");
   2288   Selector InitSel = getContext().Selectors.getSelector(0, &II);
   2289   RValue InitRV =
   2290     Runtime.GenerateMessageSend(*this, ReturnValueSlot(),
   2291                                 getContext().getObjCIdType(),
   2292                                 InitSel, Receiver, Args);
   2293   return InitRV.getScalarVal();
   2294 }
   2295 
   2296 /// Produce the code to do a primitive release.
   2297 /// [tmp drain];
   2298 void CodeGenFunction::EmitObjCMRRAutoreleasePoolPop(llvm::Value *Arg) {
   2299   IdentifierInfo *II = &CGM.getContext().Idents.get("drain");
   2300   Selector DrainSel = getContext().Selectors.getSelector(0, &II);
   2301   CallArgList Args;
   2302   CGM.getObjCRuntime().GenerateMessageSend(*this, ReturnValueSlot(),
   2303                               getContext().VoidTy, DrainSel, Arg, Args);
   2304 }
   2305 
   2306 void CodeGenFunction::destroyARCStrongPrecise(CodeGenFunction &CGF,
   2307                                               llvm::Value *addr,
   2308                                               QualType type) {
   2309   CGF.EmitARCDestroyStrong(addr, ARCPreciseLifetime);
   2310 }
   2311 
   2312 void CodeGenFunction::destroyARCStrongImprecise(CodeGenFunction &CGF,
   2313                                                 llvm::Value *addr,
   2314                                                 QualType type) {
   2315   CGF.EmitARCDestroyStrong(addr, ARCImpreciseLifetime);
   2316 }
   2317 
   2318 void CodeGenFunction::destroyARCWeak(CodeGenFunction &CGF,
   2319                                      llvm::Value *addr,
   2320                                      QualType type) {
   2321   CGF.EmitARCDestroyWeak(addr);
   2322 }
   2323 
   2324 namespace {
   2325   struct CallObjCAutoreleasePoolObject : EHScopeStack::Cleanup {
   2326     llvm::Value *Token;
   2327 
   2328     CallObjCAutoreleasePoolObject(llvm::Value *token) : Token(token) {}
   2329 
   2330     void Emit(CodeGenFunction &CGF, Flags flags) override {
   2331       CGF.EmitObjCAutoreleasePoolPop(Token);
   2332     }
   2333   };
   2334   struct CallObjCMRRAutoreleasePoolObject : EHScopeStack::Cleanup {
   2335     llvm::Value *Token;
   2336 
   2337     CallObjCMRRAutoreleasePoolObject(llvm::Value *token) : Token(token) {}
   2338 
   2339     void Emit(CodeGenFunction &CGF, Flags flags) override {
   2340       CGF.EmitObjCMRRAutoreleasePoolPop(Token);
   2341     }
   2342   };
   2343 }
   2344 
   2345 void CodeGenFunction::EmitObjCAutoreleasePoolCleanup(llvm::Value *Ptr) {
   2346   if (CGM.getLangOpts().ObjCAutoRefCount)
   2347     EHStack.pushCleanup<CallObjCAutoreleasePoolObject>(NormalCleanup, Ptr);
   2348   else
   2349     EHStack.pushCleanup<CallObjCMRRAutoreleasePoolObject>(NormalCleanup, Ptr);
   2350 }
   2351 
   2352 static TryEmitResult tryEmitARCRetainLoadOfScalar(CodeGenFunction &CGF,
   2353                                                   LValue lvalue,
   2354                                                   QualType type) {
   2355   switch (type.getObjCLifetime()) {
   2356   case Qualifiers::OCL_None:
   2357   case Qualifiers::OCL_ExplicitNone:
   2358   case Qualifiers::OCL_Strong:
   2359   case Qualifiers::OCL_Autoreleasing:
   2360     return TryEmitResult(CGF.EmitLoadOfLValue(lvalue,
   2361                                               SourceLocation()).getScalarVal(),
   2362                          false);
   2363 
   2364   case Qualifiers::OCL_Weak:
   2365     return TryEmitResult(CGF.EmitARCLoadWeakRetained(lvalue.getAddress()),
   2366                          true);
   2367   }
   2368 
   2369   llvm_unreachable("impossible lifetime!");
   2370 }
   2371 
   2372 static TryEmitResult tryEmitARCRetainLoadOfScalar(CodeGenFunction &CGF,
   2373                                                   const Expr *e) {
   2374   e = e->IgnoreParens();
   2375   QualType type = e->getType();
   2376 
   2377   // If we're loading retained from a __strong xvalue, we can avoid
   2378   // an extra retain/release pair by zeroing out the source of this
   2379   // "move" operation.
   2380   if (e->isXValue() &&
   2381       !type.isConstQualified() &&
   2382       type.getObjCLifetime() == Qualifiers::OCL_Strong) {
   2383     // Emit the lvalue.
   2384     LValue lv = CGF.EmitLValue(e);
   2385 
   2386     // Load the object pointer.
   2387     llvm::Value *result = CGF.EmitLoadOfLValue(lv,
   2388                                                SourceLocation()).getScalarVal();
   2389 
   2390     // Set the source pointer to NULL.
   2391     CGF.EmitStoreOfScalar(getNullForVariable(lv.getAddress()), lv);
   2392 
   2393     return TryEmitResult(result, true);
   2394   }
   2395 
   2396   // As a very special optimization, in ARC++, if the l-value is the
   2397   // result of a non-volatile assignment, do a simple retain of the
   2398   // result of the call to objc_storeWeak instead of reloading.
   2399   if (CGF.getLangOpts().CPlusPlus &&
   2400       !type.isVolatileQualified() &&
   2401       type.getObjCLifetime() == Qualifiers::OCL_Weak &&
   2402       isa<BinaryOperator>(e) &&
   2403       cast<BinaryOperator>(e)->getOpcode() == BO_Assign)
   2404     return TryEmitResult(CGF.EmitScalarExpr(e), false);
   2405 
   2406   return tryEmitARCRetainLoadOfScalar(CGF, CGF.EmitLValue(e), type);
   2407 }
   2408 
   2409 static llvm::Value *emitARCRetainAfterCall(CodeGenFunction &CGF,
   2410                                            llvm::Value *value);
   2411 
   2412 /// Given that the given expression is some sort of call (which does
   2413 /// not return retained), emit a retain following it.
   2414 static llvm::Value *emitARCRetainCall(CodeGenFunction &CGF, const Expr *e) {
   2415   llvm::Value *value = CGF.EmitScalarExpr(e);
   2416   return emitARCRetainAfterCall(CGF, value);
   2417 }
   2418 
   2419 static llvm::Value *emitARCRetainAfterCall(CodeGenFunction &CGF,
   2420                                            llvm::Value *value) {
   2421   if (llvm::CallInst *call = dyn_cast<llvm::CallInst>(value)) {
   2422     CGBuilderTy::InsertPoint ip = CGF.Builder.saveIP();
   2423 
   2424     // Place the retain immediately following the call.
   2425     CGF.Builder.SetInsertPoint(call->getParent(),
   2426                                ++llvm::BasicBlock::iterator(call));
   2427     value = CGF.EmitARCRetainAutoreleasedReturnValue(value);
   2428 
   2429     CGF.Builder.restoreIP(ip);
   2430     return value;
   2431   } else if (llvm::InvokeInst *invoke = dyn_cast<llvm::InvokeInst>(value)) {
   2432     CGBuilderTy::InsertPoint ip = CGF.Builder.saveIP();
   2433 
   2434     // Place the retain at the beginning of the normal destination block.
   2435     llvm::BasicBlock *BB = invoke->getNormalDest();
   2436     CGF.Builder.SetInsertPoint(BB, BB->begin());
   2437     value = CGF.EmitARCRetainAutoreleasedReturnValue(value);
   2438 
   2439     CGF.Builder.restoreIP(ip);
   2440     return value;
   2441 
   2442   // Bitcasts can arise because of related-result returns.  Rewrite
   2443   // the operand.
   2444   } else if (llvm::BitCastInst *bitcast = dyn_cast<llvm::BitCastInst>(value)) {
   2445     llvm::Value *operand = bitcast->getOperand(0);
   2446     operand = emitARCRetainAfterCall(CGF, operand);
   2447     bitcast->setOperand(0, operand);
   2448     return bitcast;
   2449 
   2450   // Generic fall-back case.
   2451   } else {
   2452     // Retain using the non-block variant: we never need to do a copy
   2453     // of a block that's been returned to us.
   2454     return CGF.EmitARCRetainNonBlock(value);
   2455   }
   2456 }
   2457 
   2458 /// Determine whether it might be important to emit a separate
   2459 /// objc_retain_block on the result of the given expression, or
   2460 /// whether it's okay to just emit it in a +1 context.
   2461 static bool shouldEmitSeparateBlockRetain(const Expr *e) {
   2462   assert(e->getType()->isBlockPointerType());
   2463   e = e->IgnoreParens();
   2464 
   2465   // For future goodness, emit block expressions directly in +1
   2466   // contexts if we can.
   2467   if (isa<BlockExpr>(e))
   2468     return false;
   2469 
   2470   if (const CastExpr *cast = dyn_cast<CastExpr>(e)) {
   2471     switch (cast->getCastKind()) {
   2472     // Emitting these operations in +1 contexts is goodness.
   2473     case CK_LValueToRValue:
   2474     case CK_ARCReclaimReturnedObject:
   2475     case CK_ARCConsumeObject:
   2476     case CK_ARCProduceObject:
   2477       return false;
   2478 
   2479     // These operations preserve a block type.
   2480     case CK_NoOp:
   2481     case CK_BitCast:
   2482       return shouldEmitSeparateBlockRetain(cast->getSubExpr());
   2483 
   2484     // These operations are known to be bad (or haven't been considered).
   2485     case CK_AnyPointerToBlockPointerCast:
   2486     default:
   2487       return true;
   2488     }
   2489   }
   2490 
   2491   return true;
   2492 }
   2493 
   2494 /// Try to emit a PseudoObjectExpr at +1.
   2495 ///
   2496 /// This massively duplicates emitPseudoObjectRValue.
   2497 static TryEmitResult tryEmitARCRetainPseudoObject(CodeGenFunction &CGF,
   2498                                                   const PseudoObjectExpr *E) {
   2499   SmallVector<CodeGenFunction::OpaqueValueMappingData, 4> opaques;
   2500 
   2501   // Find the result expression.
   2502   const Expr *resultExpr = E->getResultExpr();
   2503   assert(resultExpr);
   2504   TryEmitResult result;
   2505 
   2506   for (PseudoObjectExpr::const_semantics_iterator
   2507          i = E->semantics_begin(), e = E->semantics_end(); i != e; ++i) {
   2508     const Expr *semantic = *i;
   2509 
   2510     // If this semantic expression is an opaque value, bind it
   2511     // to the result of its source expression.
   2512     if (const OpaqueValueExpr *ov = dyn_cast<OpaqueValueExpr>(semantic)) {
   2513       typedef CodeGenFunction::OpaqueValueMappingData OVMA;
   2514       OVMA opaqueData;
   2515 
   2516       // If this semantic is the result of the pseudo-object
   2517       // expression, try to evaluate the source as +1.
   2518       if (ov == resultExpr) {
   2519         assert(!OVMA::shouldBindAsLValue(ov));
   2520         result = tryEmitARCRetainScalarExpr(CGF, ov->getSourceExpr());
   2521         opaqueData = OVMA::bind(CGF, ov, RValue::get(result.getPointer()));
   2522 
   2523       // Otherwise, just bind it.
   2524       } else {
   2525         opaqueData = OVMA::bind(CGF, ov, ov->getSourceExpr());
   2526       }
   2527       opaques.push_back(opaqueData);
   2528 
   2529     // Otherwise, if the expression is the result, evaluate it
   2530     // and remember the result.
   2531     } else if (semantic == resultExpr) {
   2532       result = tryEmitARCRetainScalarExpr(CGF, semantic);
   2533 
   2534     // Otherwise, evaluate the expression in an ignored context.
   2535     } else {
   2536       CGF.EmitIgnoredExpr(semantic);
   2537     }
   2538   }
   2539 
   2540   // Unbind all the opaques now.
   2541   for (unsigned i = 0, e = opaques.size(); i != e; ++i)
   2542     opaques[i].unbind(CGF);
   2543 
   2544   return result;
   2545 }
   2546 
   2547 static TryEmitResult
   2548 tryEmitARCRetainScalarExpr(CodeGenFunction &CGF, const Expr *e) {
   2549   // We should *never* see a nested full-expression here, because if
   2550   // we fail to emit at +1, our caller must not retain after we close
   2551   // out the full-expression.
   2552   assert(!isa<ExprWithCleanups>(e));
   2553 
   2554   // The desired result type, if it differs from the type of the
   2555   // ultimate opaque expression.
   2556   llvm::Type *resultType = nullptr;
   2557 
   2558   while (true) {
   2559     e = e->IgnoreParens();
   2560 
   2561     // There's a break at the end of this if-chain;  anything
   2562     // that wants to keep looping has to explicitly continue.
   2563     if (const CastExpr *ce = dyn_cast<CastExpr>(e)) {
   2564       switch (ce->getCastKind()) {
   2565       // No-op casts don't change the type, so we just ignore them.
   2566       case CK_NoOp:
   2567         e = ce->getSubExpr();
   2568         continue;
   2569 
   2570       case CK_LValueToRValue: {
   2571         TryEmitResult loadResult
   2572           = tryEmitARCRetainLoadOfScalar(CGF, ce->getSubExpr());
   2573         if (resultType) {
   2574           llvm::Value *value = loadResult.getPointer();
   2575           value = CGF.Builder.CreateBitCast(value, resultType);
   2576           loadResult.setPointer(value);
   2577         }
   2578         return loadResult;
   2579       }
   2580 
   2581       // These casts can change the type, so remember that and
   2582       // soldier on.  We only need to remember the outermost such
   2583       // cast, though.
   2584       case CK_CPointerToObjCPointerCast:
   2585       case CK_BlockPointerToObjCPointerCast:
   2586       case CK_AnyPointerToBlockPointerCast:
   2587       case CK_BitCast:
   2588         if (!resultType)
   2589           resultType = CGF.ConvertType(ce->getType());
   2590         e = ce->getSubExpr();
   2591         assert(e->getType()->hasPointerRepresentation());
   2592         continue;
   2593 
   2594       // For consumptions, just emit the subexpression and thus elide
   2595       // the retain/release pair.
   2596       case CK_ARCConsumeObject: {
   2597         llvm::Value *result = CGF.EmitScalarExpr(ce->getSubExpr());
   2598         if (resultType) result = CGF.Builder.CreateBitCast(result, resultType);
   2599         return TryEmitResult(result, true);
   2600       }
   2601 
   2602       // Block extends are net +0.  Naively, we could just recurse on
   2603       // the subexpression, but actually we need to ensure that the
   2604       // value is copied as a block, so there's a little filter here.
   2605       case CK_ARCExtendBlockObject: {
   2606         llvm::Value *result; // will be a +0 value
   2607 
   2608         // If we can't safely assume the sub-expression will produce a
   2609         // block-copied value, emit the sub-expression at +0.
   2610         if (shouldEmitSeparateBlockRetain(ce->getSubExpr())) {
   2611           result = CGF.EmitScalarExpr(ce->getSubExpr());
   2612 
   2613         // Otherwise, try to emit the sub-expression at +1 recursively.
   2614         } else {
   2615           TryEmitResult subresult
   2616             = tryEmitARCRetainScalarExpr(CGF, ce->getSubExpr());
   2617           result = subresult.getPointer();
   2618 
   2619           // If that produced a retained value, just use that,
   2620           // possibly casting down.
   2621           if (subresult.getInt()) {
   2622             if (resultType)
   2623               result = CGF.Builder.CreateBitCast(result, resultType);
   2624             return TryEmitResult(result, true);
   2625           }
   2626 
   2627           // Otherwise it's +0.
   2628         }
   2629 
   2630         // Retain the object as a block, then cast down.
   2631         result = CGF.EmitARCRetainBlock(result, /*mandatory*/ true);
   2632         if (resultType) result = CGF.Builder.CreateBitCast(result, resultType);
   2633         return TryEmitResult(result, true);
   2634       }
   2635 
   2636       // For reclaims, emit the subexpression as a retained call and
   2637       // skip the consumption.
   2638       case CK_ARCReclaimReturnedObject: {
   2639         llvm::Value *result = emitARCRetainCall(CGF, ce->getSubExpr());
   2640         if (resultType) result = CGF.Builder.CreateBitCast(result, resultType);
   2641         return TryEmitResult(result, true);
   2642       }
   2643 
   2644       default:
   2645         break;
   2646       }
   2647 
   2648     // Skip __extension__.
   2649     } else if (const UnaryOperator *op = dyn_cast<UnaryOperator>(e)) {
   2650       if (op->getOpcode() == UO_Extension) {
   2651         e = op->getSubExpr();
   2652         continue;
   2653       }
   2654 
   2655     // For calls and message sends, use the retained-call logic.
   2656     // Delegate inits are a special case in that they're the only
   2657     // returns-retained expression that *isn't* surrounded by
   2658     // a consume.
   2659     } else if (isa<CallExpr>(e) ||
   2660                (isa<ObjCMessageExpr>(e) &&
   2661                 !cast<ObjCMessageExpr>(e)->isDelegateInitCall())) {
   2662       llvm::Value *result = emitARCRetainCall(CGF, e);
   2663       if (resultType) result = CGF.Builder.CreateBitCast(result, resultType);
   2664       return TryEmitResult(result, true);
   2665 
   2666     // Look through pseudo-object expressions.
   2667     } else if (const PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
   2668       TryEmitResult result
   2669         = tryEmitARCRetainPseudoObject(CGF, pseudo);
   2670       if (resultType) {
   2671         llvm::Value *value = result.getPointer();
   2672         value = CGF.Builder.CreateBitCast(value, resultType);
   2673         result.setPointer(value);
   2674       }
   2675       return result;
   2676     }
   2677 
   2678     // Conservatively halt the search at any other expression kind.
   2679     break;
   2680   }
   2681 
   2682   // We didn't find an obvious production, so emit what we've got and
   2683   // tell the caller that we didn't manage to retain.
   2684   llvm::Value *result = CGF.EmitScalarExpr(e);
   2685   if (resultType) result = CGF.Builder.CreateBitCast(result, resultType);
   2686   return TryEmitResult(result, false);
   2687 }
   2688 
   2689 static llvm::Value *emitARCRetainLoadOfScalar(CodeGenFunction &CGF,
   2690                                                 LValue lvalue,
   2691                                                 QualType type) {
   2692   TryEmitResult result = tryEmitARCRetainLoadOfScalar(CGF, lvalue, type);
   2693   llvm::Value *value = result.getPointer();
   2694   if (!result.getInt())
   2695     value = CGF.EmitARCRetain(type, value);
   2696   return value;
   2697 }
   2698 
   2699 /// EmitARCRetainScalarExpr - Semantically equivalent to
   2700 /// EmitARCRetainObject(e->getType(), EmitScalarExpr(e)), but making a
   2701 /// best-effort attempt to peephole expressions that naturally produce
   2702 /// retained objects.
   2703 llvm::Value *CodeGenFunction::EmitARCRetainScalarExpr(const Expr *e) {
   2704   // The retain needs to happen within the full-expression.
   2705   if (const ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(e)) {
   2706     enterFullExpression(cleanups);
   2707     RunCleanupsScope scope(*this);
   2708     return EmitARCRetainScalarExpr(cleanups->getSubExpr());
   2709   }
   2710 
   2711   TryEmitResult result = tryEmitARCRetainScalarExpr(*this, e);
   2712   llvm::Value *value = result.getPointer();
   2713   if (!result.getInt())
   2714     value = EmitARCRetain(e->getType(), value);
   2715   return value;
   2716 }
   2717 
   2718 llvm::Value *
   2719 CodeGenFunction::EmitARCRetainAutoreleaseScalarExpr(const Expr *e) {
   2720   // The retain needs to happen within the full-expression.
   2721   if (const ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(e)) {
   2722     enterFullExpression(cleanups);
   2723     RunCleanupsScope scope(*this);
   2724     return EmitARCRetainAutoreleaseScalarExpr(cleanups->getSubExpr());
   2725   }
   2726 
   2727   TryEmitResult result = tryEmitARCRetainScalarExpr(*this, e);
   2728   llvm::Value *value = result.getPointer();
   2729   if (result.getInt())
   2730     value = EmitARCAutorelease(value);
   2731   else
   2732     value = EmitARCRetainAutorelease(e->getType(), value);
   2733   return value;
   2734 }
   2735 
   2736 llvm::Value *CodeGenFunction::EmitARCExtendBlockObject(const Expr *e) {
   2737   llvm::Value *result;
   2738   bool doRetain;
   2739 
   2740   if (shouldEmitSeparateBlockRetain(e)) {
   2741     result = EmitScalarExpr(e);
   2742     doRetain = true;
   2743   } else {
   2744     TryEmitResult subresult = tryEmitARCRetainScalarExpr(*this, e);
   2745     result = subresult.getPointer();
   2746     doRetain = !subresult.getInt();
   2747   }
   2748 
   2749   if (doRetain)
   2750     result = EmitARCRetainBlock(result, /*mandatory*/ true);
   2751   return EmitObjCConsumeObject(e->getType(), result);
   2752 }
   2753 
   2754 llvm::Value *CodeGenFunction::EmitObjCThrowOperand(const Expr *expr) {
   2755   // In ARC, retain and autorelease the expression.
   2756   if (getLangOpts().ObjCAutoRefCount) {
   2757     // Do so before running any cleanups for the full-expression.
   2758     // EmitARCRetainAutoreleaseScalarExpr does this for us.
   2759     return EmitARCRetainAutoreleaseScalarExpr(expr);
   2760   }
   2761 
   2762   // Otherwise, use the normal scalar-expression emission.  The
   2763   // exception machinery doesn't do anything special with the
   2764   // exception like retaining it, so there's no safety associated with
   2765   // only running cleanups after the throw has started, and when it
   2766   // matters it tends to be substantially inferior code.
   2767   return EmitScalarExpr(expr);
   2768 }
   2769 
   2770 std::pair<LValue,llvm::Value*>
   2771 CodeGenFunction::EmitARCStoreStrong(const BinaryOperator *e,
   2772                                     bool ignored) {
   2773   // Evaluate the RHS first.
   2774   TryEmitResult result = tryEmitARCRetainScalarExpr(*this, e->getRHS());
   2775   llvm::Value *value = result.getPointer();
   2776 
   2777   bool hasImmediateRetain = result.getInt();
   2778 
   2779   // If we didn't emit a retained object, and the l-value is of block
   2780   // type, then we need to emit the block-retain immediately in case
   2781   // it invalidates the l-value.
   2782   if (!hasImmediateRetain && e->getType()->isBlockPointerType()) {
   2783     value = EmitARCRetainBlock(value, /*mandatory*/ false);
   2784     hasImmediateRetain = true;
   2785   }
   2786 
   2787   LValue lvalue = EmitLValue(e->getLHS());
   2788 
   2789   // If the RHS was emitted retained, expand this.
   2790   if (hasImmediateRetain) {
   2791     llvm::Value *oldValue = EmitLoadOfScalar(lvalue, SourceLocation());
   2792     EmitStoreOfScalar(value, lvalue);
   2793     EmitARCRelease(oldValue, lvalue.isARCPreciseLifetime());
   2794   } else {
   2795     value = EmitARCStoreStrong(lvalue, value, ignored);
   2796   }
   2797 
   2798   return std::pair<LValue,llvm::Value*>(lvalue, value);
   2799 }
   2800 
   2801 std::pair<LValue,llvm::Value*>
   2802 CodeGenFunction::EmitARCStoreAutoreleasing(const BinaryOperator *e) {
   2803   llvm::Value *value = EmitARCRetainAutoreleaseScalarExpr(e->getRHS());
   2804   LValue lvalue = EmitLValue(e->getLHS());
   2805 
   2806   EmitStoreOfScalar(value, lvalue);
   2807 
   2808   return std::pair<LValue,llvm::Value*>(lvalue, value);
   2809 }
   2810 
   2811 void CodeGenFunction::EmitObjCAutoreleasePoolStmt(
   2812                                           const ObjCAutoreleasePoolStmt &ARPS) {
   2813   const Stmt *subStmt = ARPS.getSubStmt();
   2814   const CompoundStmt &S = cast<CompoundStmt>(*subStmt);
   2815 
   2816   CGDebugInfo *DI = getDebugInfo();
   2817   if (DI)
   2818     DI->EmitLexicalBlockStart(Builder, S.getLBracLoc());
   2819 
   2820   // Keep track of the current cleanup stack depth.
   2821   RunCleanupsScope Scope(*this);
   2822   if (CGM.getLangOpts().ObjCRuntime.hasNativeARC()) {
   2823     llvm::Value *token = EmitObjCAutoreleasePoolPush();
   2824     EHStack.pushCleanup<CallObjCAutoreleasePoolObject>(NormalCleanup, token);
   2825   } else {
   2826     llvm::Value *token = EmitObjCMRRAutoreleasePoolPush();
   2827     EHStack.pushCleanup<CallObjCMRRAutoreleasePoolObject>(NormalCleanup, token);
   2828   }
   2829 
   2830   for (const auto *I : S.body())
   2831     EmitStmt(I);
   2832 
   2833   if (DI)
   2834     DI->EmitLexicalBlockEnd(Builder, S.getRBracLoc());
   2835 }
   2836 
   2837 /// EmitExtendGCLifetime - Given a pointer to an Objective-C object,
   2838 /// make sure it survives garbage collection until this point.
   2839 void CodeGenFunction::EmitExtendGCLifetime(llvm::Value *object) {
   2840   // We just use an inline assembly.
   2841   llvm::FunctionType *extenderType
   2842     = llvm::FunctionType::get(VoidTy, VoidPtrTy, RequiredArgs::All);
   2843   llvm::Value *extender
   2844     = llvm::InlineAsm::get(extenderType,
   2845                            /* assembly */ "",
   2846                            /* constraints */ "r",
   2847                            /* side effects */ true);
   2848 
   2849   object = Builder.CreateBitCast(object, VoidPtrTy);
   2850   EmitNounwindRuntimeCall(extender, object);
   2851 }
   2852 
   2853 /// GenerateObjCAtomicSetterCopyHelperFunction - Given a c++ object type with
   2854 /// non-trivial copy assignment function, produce following helper function.
   2855 /// static void copyHelper(Ty *dest, const Ty *source) { *dest = *source; }
   2856 ///
   2857 llvm::Constant *
   2858 CodeGenFunction::GenerateObjCAtomicSetterCopyHelperFunction(
   2859                                         const ObjCPropertyImplDecl *PID) {
   2860   if (!getLangOpts().CPlusPlus ||
   2861       !getLangOpts().ObjCRuntime.hasAtomicCopyHelper())
   2862     return nullptr;
   2863   QualType Ty = PID->getPropertyIvarDecl()->getType();
   2864   if (!Ty->isRecordType())
   2865     return nullptr;
   2866   const ObjCPropertyDecl *PD = PID->getPropertyDecl();
   2867   if ((!(PD->getPropertyAttributes() & ObjCPropertyDecl::OBJC_PR_atomic)))
   2868     return nullptr;
   2869   llvm::Constant *HelperFn = nullptr;
   2870   if (hasTrivialSetExpr(PID))
   2871     return nullptr;
   2872   assert(PID->getSetterCXXAssignment() && "SetterCXXAssignment - null");
   2873   if ((HelperFn = CGM.getAtomicSetterHelperFnMap(Ty)))
   2874     return HelperFn;
   2875 
   2876   ASTContext &C = getContext();
   2877   IdentifierInfo *II
   2878     = &CGM.getContext().Idents.get("__assign_helper_atomic_property_");
   2879   FunctionDecl *FD = FunctionDecl::Create(C,
   2880                                           C.getTranslationUnitDecl(),
   2881                                           SourceLocation(),
   2882                                           SourceLocation(), II, C.VoidTy,
   2883                                           nullptr, SC_Static,
   2884                                           false,
   2885                                           false);
   2886 
   2887   QualType DestTy = C.getPointerType(Ty);
   2888   QualType SrcTy = Ty;
   2889   SrcTy.addConst();
   2890   SrcTy = C.getPointerType(SrcTy);
   2891 
   2892   FunctionArgList args;
   2893   ImplicitParamDecl dstDecl(getContext(), FD, SourceLocation(), nullptr,DestTy);
   2894   args.push_back(&dstDecl);
   2895   ImplicitParamDecl srcDecl(getContext(), FD, SourceLocation(), nullptr, SrcTy);
   2896   args.push_back(&srcDecl);
   2897 
   2898   const CGFunctionInfo &FI = CGM.getTypes().arrangeFreeFunctionDeclaration(
   2899       C.VoidTy, args, FunctionType::ExtInfo(), RequiredArgs::All);
   2900 
   2901   llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
   2902 
   2903   llvm::Function *Fn =
   2904     llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
   2905                            "__assign_helper_atomic_property_",
   2906                            &CGM.getModule());
   2907 
   2908   StartFunction(FD, C.VoidTy, Fn, FI, args);
   2909 
   2910   DeclRefExpr DstExpr(&dstDecl, false, DestTy,
   2911                       VK_RValue, SourceLocation());
   2912   UnaryOperator DST(&DstExpr, UO_Deref, DestTy->getPointeeType(),
   2913                     VK_LValue, OK_Ordinary, SourceLocation());
   2914 
   2915   DeclRefExpr SrcExpr(&srcDecl, false, SrcTy,
   2916                       VK_RValue, SourceLocation());
   2917   UnaryOperator SRC(&SrcExpr, UO_Deref, SrcTy->getPointeeType(),
   2918                     VK_LValue, OK_Ordinary, SourceLocation());
   2919 
   2920   Expr *Args[2] = { &DST, &SRC };
   2921   CallExpr *CalleeExp = cast<CallExpr>(PID->getSetterCXXAssignment());
   2922   CXXOperatorCallExpr TheCall(C, OO_Equal, CalleeExp->getCallee(),
   2923                               Args, DestTy->getPointeeType(),
   2924                               VK_LValue, SourceLocation(), false);
   2925 
   2926   EmitStmt(&TheCall);
   2927 
   2928   FinishFunction();
   2929   HelperFn = llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
   2930   CGM.setAtomicSetterHelperFnMap(Ty, HelperFn);
   2931   return HelperFn;
   2932 }
   2933 
   2934 llvm::Constant *
   2935 CodeGenFunction::GenerateObjCAtomicGetterCopyHelperFunction(
   2936                                             const ObjCPropertyImplDecl *PID) {
   2937   if (!getLangOpts().CPlusPlus ||
   2938       !getLangOpts().ObjCRuntime.hasAtomicCopyHelper())
   2939     return nullptr;
   2940   const ObjCPropertyDecl *PD = PID->getPropertyDecl();
   2941   QualType Ty = PD->getType();
   2942   if (!Ty->isRecordType())
   2943     return nullptr;
   2944   if ((!(PD->getPropertyAttributes() & ObjCPropertyDecl::OBJC_PR_atomic)))
   2945     return nullptr;
   2946   llvm::Constant *HelperFn = nullptr;
   2947 
   2948   if (hasTrivialGetExpr(PID))
   2949     return nullptr;
   2950   assert(PID->getGetterCXXConstructor() && "getGetterCXXConstructor - null");
   2951   if ((HelperFn = CGM.getAtomicGetterHelperFnMap(Ty)))
   2952     return HelperFn;
   2953 
   2954 
   2955   ASTContext &C = getContext();
   2956   IdentifierInfo *II
   2957   = &CGM.getContext().Idents.get("__copy_helper_atomic_property_");
   2958   FunctionDecl *FD = FunctionDecl::Create(C,
   2959                                           C.getTranslationUnitDecl(),
   2960                                           SourceLocation(),
   2961                                           SourceLocation(), II, C.VoidTy,
   2962                                           nullptr, SC_Static,
   2963                                           false,
   2964                                           false);
   2965 
   2966   QualType DestTy = C.getPointerType(Ty);
   2967   QualType SrcTy = Ty;
   2968   SrcTy.addConst();
   2969   SrcTy = C.getPointerType(SrcTy);
   2970 
   2971   FunctionArgList args;
   2972   ImplicitParamDecl dstDecl(getContext(), FD, SourceLocation(), nullptr,DestTy);
   2973   args.push_back(&dstDecl);
   2974   ImplicitParamDecl srcDecl(getContext(), FD, SourceLocation(), nullptr, SrcTy);
   2975   args.push_back(&srcDecl);
   2976 
   2977   const CGFunctionInfo &FI = CGM.getTypes().arrangeFreeFunctionDeclaration(
   2978       C.VoidTy, args, FunctionType::ExtInfo(), RequiredArgs::All);
   2979 
   2980   llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
   2981 
   2982   llvm::Function *Fn =
   2983   llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
   2984                          "__copy_helper_atomic_property_", &CGM.getModule());
   2985 
   2986   StartFunction(FD, C.VoidTy, Fn, FI, args);
   2987 
   2988   DeclRefExpr SrcExpr(&srcDecl, false, SrcTy,
   2989                       VK_RValue, SourceLocation());
   2990 
   2991   UnaryOperator SRC(&SrcExpr, UO_Deref, SrcTy->getPointeeType(),
   2992                     VK_LValue, OK_Ordinary, SourceLocation());
   2993 
   2994   CXXConstructExpr *CXXConstExpr =
   2995     cast<CXXConstructExpr>(PID->getGetterCXXConstructor());
   2996 
   2997   SmallVector<Expr*, 4> ConstructorArgs;
   2998   ConstructorArgs.push_back(&SRC);
   2999   CXXConstructExpr::arg_iterator A = CXXConstExpr->arg_begin();
   3000   ++A;
   3001 
   3002   for (CXXConstructExpr::arg_iterator AEnd = CXXConstExpr->arg_end();
   3003        A != AEnd; ++A)
   3004     ConstructorArgs.push_back(*A);
   3005 
   3006   CXXConstructExpr *TheCXXConstructExpr =
   3007     CXXConstructExpr::Create(C, Ty, SourceLocation(),
   3008                              CXXConstExpr->getConstructor(),
   3009                              CXXConstExpr->isElidable(),
   3010                              ConstructorArgs,
   3011                              CXXConstExpr->hadMultipleCandidates(),
   3012                              CXXConstExpr->isListInitialization(),
   3013                              CXXConstExpr->isStdInitListInitialization(),
   3014                              CXXConstExpr->requiresZeroInitialization(),
   3015                              CXXConstExpr->getConstructionKind(),
   3016                              SourceRange());
   3017 
   3018   DeclRefExpr DstExpr(&dstDecl, false, DestTy,
   3019                       VK_RValue, SourceLocation());
   3020 
   3021   RValue DV = EmitAnyExpr(&DstExpr);
   3022   CharUnits Alignment
   3023     = getContext().getTypeAlignInChars(TheCXXConstructExpr->getType());
   3024   EmitAggExpr(TheCXXConstructExpr,
   3025               AggValueSlot::forAddr(DV.getScalarVal(), Alignment, Qualifiers(),
   3026                                     AggValueSlot::IsDestructed,
   3027                                     AggValueSlot::DoesNotNeedGCBarriers,
   3028                                     AggValueSlot::IsNotAliased));
   3029 
   3030   FinishFunction();
   3031   HelperFn = llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
   3032   CGM.setAtomicGetterHelperFnMap(Ty, HelperFn);
   3033   return HelperFn;
   3034 }
   3035 
   3036 llvm::Value *
   3037 CodeGenFunction::EmitBlockCopyAndAutorelease(llvm::Value *Block, QualType Ty) {
   3038   // Get selectors for retain/autorelease.
   3039   IdentifierInfo *CopyID = &getContext().Idents.get("copy");
   3040   Selector CopySelector =
   3041       getContext().Selectors.getNullarySelector(CopyID);
   3042   IdentifierInfo *AutoreleaseID = &getContext().Idents.get("autorelease");
   3043   Selector AutoreleaseSelector =
   3044       getContext().Selectors.getNullarySelector(AutoreleaseID);
   3045 
   3046   // Emit calls to retain/autorelease.
   3047   CGObjCRuntime &Runtime = CGM.getObjCRuntime();
   3048   llvm::Value *Val = Block;
   3049   RValue Result;
   3050   Result = Runtime.GenerateMessageSend(*this, ReturnValueSlot(),
   3051                                        Ty, CopySelector,
   3052                                        Val, CallArgList(), nullptr, nullptr);
   3053   Val = Result.getScalarVal();
   3054   Result = Runtime.GenerateMessageSend(*this, ReturnValueSlot(),
   3055                                        Ty, AutoreleaseSelector,
   3056                                        Val, CallArgList(), nullptr, nullptr);
   3057   Val = Result.getScalarVal();
   3058   return Val;
   3059 }
   3060 
   3061 
   3062 CGObjCRuntime::~CGObjCRuntime() {}
   3063