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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 AdjustObjCObjectType(CodeGenFunction &CGF,
     35                                    QualType ET,
     36                                    RValue Result);
     37 
     38 /// Given the address of a variable of pointer type, find the correct
     39 /// null to store into it.
     40 static llvm::Constant *getNullForVariable(Address addr) {
     41   llvm::Type *type = addr.getElementType();
     42   return llvm::ConstantPointerNull::get(cast<llvm::PointerType>(type));
     43 }
     44 
     45 /// Emits an instance of NSConstantString representing the object.
     46 llvm::Value *CodeGenFunction::EmitObjCStringLiteral(const ObjCStringLiteral *E)
     47 {
     48   llvm::Constant *C =
     49       CGM.getObjCRuntime().GenerateConstantString(E->getString()).getPointer();
     50   // FIXME: This bitcast should just be made an invariant on the Runtime.
     51   return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType()));
     52 }
     53 
     54 /// EmitObjCBoxedExpr - This routine generates code to call
     55 /// the appropriate expression boxing method. This will either be
     56 /// one of +[NSNumber numberWith<Type>:], or +[NSString stringWithUTF8String:],
     57 /// or [NSValue valueWithBytes:objCType:].
     58 ///
     59 llvm::Value *
     60 CodeGenFunction::EmitObjCBoxedExpr(const ObjCBoxedExpr *E) {
     61   // Generate the correct selector for this literal's concrete type.
     62   // Get the method.
     63   const ObjCMethodDecl *BoxingMethod = E->getBoxingMethod();
     64   const Expr *SubExpr = E->getSubExpr();
     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   const ParmVarDecl *ArgDecl = *BoxingMethod->param_begin();
     78   QualType ArgQT = ArgDecl->getType().getUnqualifiedType();
     79 
     80   // ObjCBoxedExpr supports boxing of structs and unions
     81   // via [NSValue valueWithBytes:objCType:]
     82   const QualType ValueType(SubExpr->getType().getCanonicalType());
     83   if (ValueType->isObjCBoxableRecordType()) {
     84     // Emit CodeGen for first parameter
     85     // and cast value to correct type
     86     Address Temporary = CreateMemTemp(SubExpr->getType());
     87     EmitAnyExprToMem(SubExpr, Temporary, Qualifiers(), /*isInit*/ true);
     88     Address BitCast = Builder.CreateBitCast(Temporary, ConvertType(ArgQT));
     89     Args.add(RValue::get(BitCast.getPointer()), ArgQT);
     90 
     91     // Create char array to store type encoding
     92     std::string Str;
     93     getContext().getObjCEncodingForType(ValueType, Str);
     94     llvm::Constant *GV = CGM.GetAddrOfConstantCString(Str).getPointer();
     95 
     96     // Cast type encoding to correct type
     97     const ParmVarDecl *EncodingDecl = BoxingMethod->parameters()[1];
     98     QualType EncodingQT = EncodingDecl->getType().getUnqualifiedType();
     99     llvm::Value *Cast = Builder.CreateBitCast(GV, ConvertType(EncodingQT));
    100 
    101     Args.add(RValue::get(Cast), EncodingQT);
    102   } else {
    103     Args.add(EmitAnyExpr(SubExpr), ArgQT);
    104   }
    105 
    106   RValue result = Runtime.GenerateMessageSend(
    107       *this, ReturnValueSlot(), BoxingMethod->getReturnType(), Sel, Receiver,
    108       Args, ClassDecl, BoxingMethod);
    109   return Builder.CreateBitCast(result.getScalarVal(),
    110                                ConvertType(E->getType()));
    111 }
    112 
    113 llvm::Value *CodeGenFunction::EmitObjCCollectionLiteral(const Expr *E,
    114                                     const ObjCMethodDecl *MethodWithObjects) {
    115   ASTContext &Context = CGM.getContext();
    116   const ObjCDictionaryLiteral *DLE = nullptr;
    117   const ObjCArrayLiteral *ALE = dyn_cast<ObjCArrayLiteral>(E);
    118   if (!ALE)
    119     DLE = cast<ObjCDictionaryLiteral>(E);
    120 
    121   // Compute the type of the array we're initializing.
    122   uint64_t NumElements =
    123     ALE ? ALE->getNumElements() : DLE->getNumElements();
    124   llvm::APInt APNumElements(Context.getTypeSize(Context.getSizeType()),
    125                             NumElements);
    126   QualType ElementType = Context.getObjCIdType().withConst();
    127   QualType ElementArrayType
    128     = Context.getConstantArrayType(ElementType, APNumElements,
    129                                    ArrayType::Normal, /*IndexTypeQuals=*/0);
    130 
    131   // Allocate the temporary array(s).
    132   Address Objects = CreateMemTemp(ElementArrayType, "objects");
    133   Address Keys = Address::invalid();
    134   if (DLE)
    135     Keys = CreateMemTemp(ElementArrayType, "keys");
    136 
    137   // In ARC, we may need to do extra work to keep all the keys and
    138   // values alive until after the call.
    139   SmallVector<llvm::Value *, 16> NeededObjects;
    140   bool TrackNeededObjects =
    141     (getLangOpts().ObjCAutoRefCount &&
    142     CGM.getCodeGenOpts().OptimizationLevel != 0);
    143 
    144   // Perform the actual initialialization of the array(s).
    145   for (uint64_t i = 0; i < NumElements; i++) {
    146     if (ALE) {
    147       // Emit the element and store it to the appropriate array slot.
    148       const Expr *Rhs = ALE->getElement(i);
    149       LValue LV = MakeAddrLValue(
    150           Builder.CreateConstArrayGEP(Objects, i, getPointerSize()),
    151           ElementType, AlignmentSource::Decl);
    152 
    153       llvm::Value *value = EmitScalarExpr(Rhs);
    154       EmitStoreThroughLValue(RValue::get(value), LV, true);
    155       if (TrackNeededObjects) {
    156         NeededObjects.push_back(value);
    157       }
    158     } else {
    159       // Emit the key and store it to the appropriate array slot.
    160       const Expr *Key = DLE->getKeyValueElement(i).Key;
    161       LValue KeyLV = MakeAddrLValue(
    162           Builder.CreateConstArrayGEP(Keys, i, getPointerSize()),
    163           ElementType, AlignmentSource::Decl);
    164       llvm::Value *keyValue = EmitScalarExpr(Key);
    165       EmitStoreThroughLValue(RValue::get(keyValue), KeyLV, /*isInit=*/true);
    166 
    167       // Emit the value and store it to the appropriate array slot.
    168       const Expr *Value = DLE->getKeyValueElement(i).Value;
    169       LValue ValueLV = MakeAddrLValue(
    170           Builder.CreateConstArrayGEP(Objects, i, getPointerSize()),
    171           ElementType, AlignmentSource::Decl);
    172       llvm::Value *valueValue = EmitScalarExpr(Value);
    173       EmitStoreThroughLValue(RValue::get(valueValue), ValueLV, /*isInit=*/true);
    174       if (TrackNeededObjects) {
    175         NeededObjects.push_back(keyValue);
    176         NeededObjects.push_back(valueValue);
    177       }
    178     }
    179   }
    180 
    181   // Generate the argument list.
    182   CallArgList Args;
    183   ObjCMethodDecl::param_const_iterator PI = MethodWithObjects->param_begin();
    184   const ParmVarDecl *argDecl = *PI++;
    185   QualType ArgQT = argDecl->getType().getUnqualifiedType();
    186   Args.add(RValue::get(Objects.getPointer()), ArgQT);
    187   if (DLE) {
    188     argDecl = *PI++;
    189     ArgQT = argDecl->getType().getUnqualifiedType();
    190     Args.add(RValue::get(Keys.getPointer()), ArgQT);
    191   }
    192   argDecl = *PI;
    193   ArgQT = argDecl->getType().getUnqualifiedType();
    194   llvm::Value *Count =
    195     llvm::ConstantInt::get(CGM.getTypes().ConvertType(ArgQT), NumElements);
    196   Args.add(RValue::get(Count), ArgQT);
    197 
    198   // Generate a reference to the class pointer, which will be the receiver.
    199   Selector Sel = MethodWithObjects->getSelector();
    200   QualType ResultType = E->getType();
    201   const ObjCObjectPointerType *InterfacePointerType
    202     = ResultType->getAsObjCInterfacePointerType();
    203   ObjCInterfaceDecl *Class
    204     = InterfacePointerType->getObjectType()->getInterface();
    205   CGObjCRuntime &Runtime = CGM.getObjCRuntime();
    206   llvm::Value *Receiver = Runtime.GetClass(*this, Class);
    207 
    208   // Generate the message send.
    209   RValue result = Runtime.GenerateMessageSend(
    210       *this, ReturnValueSlot(), MethodWithObjects->getReturnType(), Sel,
    211       Receiver, Args, Class, MethodWithObjects);
    212 
    213   // The above message send needs these objects, but in ARC they are
    214   // passed in a buffer that is essentially __unsafe_unretained.
    215   // Therefore we must prevent the optimizer from releasing them until
    216   // after the call.
    217   if (TrackNeededObjects) {
    218     EmitARCIntrinsicUse(NeededObjects);
    219   }
    220 
    221   return Builder.CreateBitCast(result.getScalarVal(),
    222                                ConvertType(E->getType()));
    223 }
    224 
    225 llvm::Value *CodeGenFunction::EmitObjCArrayLiteral(const ObjCArrayLiteral *E) {
    226   return EmitObjCCollectionLiteral(E, E->getArrayWithObjectsMethod());
    227 }
    228 
    229 llvm::Value *CodeGenFunction::EmitObjCDictionaryLiteral(
    230                                             const ObjCDictionaryLiteral *E) {
    231   return EmitObjCCollectionLiteral(E, E->getDictWithObjectsMethod());
    232 }
    233 
    234 /// Emit a selector.
    235 llvm::Value *CodeGenFunction::EmitObjCSelectorExpr(const ObjCSelectorExpr *E) {
    236   // Untyped selector.
    237   // Note that this implementation allows for non-constant strings to be passed
    238   // as arguments to @selector().  Currently, the only thing preventing this
    239   // behaviour is the type checking in the front end.
    240   return CGM.getObjCRuntime().GetSelector(*this, E->getSelector());
    241 }
    242 
    243 llvm::Value *CodeGenFunction::EmitObjCProtocolExpr(const ObjCProtocolExpr *E) {
    244   // FIXME: This should pass the Decl not the name.
    245   return CGM.getObjCRuntime().GenerateProtocolRef(*this, E->getProtocol());
    246 }
    247 
    248 /// \brief Adjust the type of an Objective-C object that doesn't match up due
    249 /// to type erasure at various points, e.g., related result types or the use
    250 /// of parameterized classes.
    251 static RValue AdjustObjCObjectType(CodeGenFunction &CGF, QualType ExpT,
    252                                    RValue Result) {
    253   if (!ExpT->isObjCRetainableType())
    254     return Result;
    255 
    256   // If the converted types are the same, we're done.
    257   llvm::Type *ExpLLVMTy = CGF.ConvertType(ExpT);
    258   if (ExpLLVMTy == Result.getScalarVal()->getType())
    259     return Result;
    260 
    261   // We have applied a substitution. Cast the rvalue appropriately.
    262   return RValue::get(CGF.Builder.CreateBitCast(Result.getScalarVal(),
    263                                                ExpLLVMTy));
    264 }
    265 
    266 /// Decide whether to extend the lifetime of the receiver of a
    267 /// returns-inner-pointer message.
    268 static bool
    269 shouldExtendReceiverForInnerPointerMessage(const ObjCMessageExpr *message) {
    270   switch (message->getReceiverKind()) {
    271 
    272   // For a normal instance message, we should extend unless the
    273   // receiver is loaded from a variable with precise lifetime.
    274   case ObjCMessageExpr::Instance: {
    275     const Expr *receiver = message->getInstanceReceiver();
    276 
    277     // Look through OVEs.
    278     if (auto opaque = dyn_cast<OpaqueValueExpr>(receiver)) {
    279       if (opaque->getSourceExpr())
    280         receiver = opaque->getSourceExpr()->IgnoreParens();
    281     }
    282 
    283     const ImplicitCastExpr *ice = dyn_cast<ImplicitCastExpr>(receiver);
    284     if (!ice || ice->getCastKind() != CK_LValueToRValue) return true;
    285     receiver = ice->getSubExpr()->IgnoreParens();
    286 
    287     // Look through OVEs.
    288     if (auto opaque = dyn_cast<OpaqueValueExpr>(receiver)) {
    289       if (opaque->getSourceExpr())
    290         receiver = opaque->getSourceExpr()->IgnoreParens();
    291     }
    292 
    293     // Only __strong variables.
    294     if (receiver->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
    295       return true;
    296 
    297     // All ivars and fields have precise lifetime.
    298     if (isa<MemberExpr>(receiver) || isa<ObjCIvarRefExpr>(receiver))
    299       return false;
    300 
    301     // Otherwise, check for variables.
    302     const DeclRefExpr *declRef = dyn_cast<DeclRefExpr>(ice->getSubExpr());
    303     if (!declRef) return true;
    304     const VarDecl *var = dyn_cast<VarDecl>(declRef->getDecl());
    305     if (!var) return true;
    306 
    307     // All variables have precise lifetime except local variables with
    308     // automatic storage duration that aren't specially marked.
    309     return (var->hasLocalStorage() &&
    310             !var->hasAttr<ObjCPreciseLifetimeAttr>());
    311   }
    312 
    313   case ObjCMessageExpr::Class:
    314   case ObjCMessageExpr::SuperClass:
    315     // It's never necessary for class objects.
    316     return false;
    317 
    318   case ObjCMessageExpr::SuperInstance:
    319     // We generally assume that 'self' lives throughout a method call.
    320     return false;
    321   }
    322 
    323   llvm_unreachable("invalid receiver kind");
    324 }
    325 
    326 /// Given an expression of ObjC pointer type, check whether it was
    327 /// immediately loaded from an ARC __weak l-value.
    328 static const Expr *findWeakLValue(const Expr *E) {
    329   assert(E->getType()->isObjCRetainableType());
    330   E = E->IgnoreParens();
    331   if (auto CE = dyn_cast<CastExpr>(E)) {
    332     if (CE->getCastKind() == CK_LValueToRValue) {
    333       if (CE->getSubExpr()->getType().getObjCLifetime() == Qualifiers::OCL_Weak)
    334         return CE->getSubExpr();
    335     }
    336   }
    337 
    338   return nullptr;
    339 }
    340 
    341 RValue CodeGenFunction::EmitObjCMessageExpr(const ObjCMessageExpr *E,
    342                                             ReturnValueSlot Return) {
    343   // Only the lookup mechanism and first two arguments of the method
    344   // implementation vary between runtimes.  We can get the receiver and
    345   // arguments in generic code.
    346 
    347   bool isDelegateInit = E->isDelegateInitCall();
    348 
    349   const ObjCMethodDecl *method = E->getMethodDecl();
    350 
    351   // If the method is -retain, and the receiver's being loaded from
    352   // a __weak variable, peephole the entire operation to objc_loadWeakRetained.
    353   if (method && E->getReceiverKind() == ObjCMessageExpr::Instance &&
    354       method->getMethodFamily() == OMF_retain) {
    355     if (auto lvalueExpr = findWeakLValue(E->getInstanceReceiver())) {
    356       LValue lvalue = EmitLValue(lvalueExpr);
    357       llvm::Value *result = EmitARCLoadWeakRetained(lvalue.getAddress());
    358       return AdjustObjCObjectType(*this, E->getType(), RValue::get(result));
    359     }
    360   }
    361 
    362   // We don't retain the receiver in delegate init calls, and this is
    363   // safe because the receiver value is always loaded from 'self',
    364   // which we zero out.  We don't want to Block_copy block receivers,
    365   // though.
    366   bool retainSelf =
    367     (!isDelegateInit &&
    368      CGM.getLangOpts().ObjCAutoRefCount &&
    369      method &&
    370      method->hasAttr<NSConsumesSelfAttr>());
    371 
    372   CGObjCRuntime &Runtime = CGM.getObjCRuntime();
    373   bool isSuperMessage = false;
    374   bool isClassMessage = false;
    375   ObjCInterfaceDecl *OID = nullptr;
    376   // Find the receiver
    377   QualType ReceiverType;
    378   llvm::Value *Receiver = nullptr;
    379   switch (E->getReceiverKind()) {
    380   case ObjCMessageExpr::Instance:
    381     ReceiverType = E->getInstanceReceiver()->getType();
    382     if (retainSelf) {
    383       TryEmitResult ter = tryEmitARCRetainScalarExpr(*this,
    384                                                    E->getInstanceReceiver());
    385       Receiver = ter.getPointer();
    386       if (ter.getInt()) retainSelf = false;
    387     } else
    388       Receiver = EmitScalarExpr(E->getInstanceReceiver());
    389     break;
    390 
    391   case ObjCMessageExpr::Class: {
    392     ReceiverType = E->getClassReceiver();
    393     const ObjCObjectType *ObjTy = ReceiverType->getAs<ObjCObjectType>();
    394     assert(ObjTy && "Invalid Objective-C class message send");
    395     OID = ObjTy->getInterface();
    396     assert(OID && "Invalid Objective-C class message send");
    397     Receiver = Runtime.GetClass(*this, OID);
    398     isClassMessage = true;
    399     break;
    400   }
    401 
    402   case ObjCMessageExpr::SuperInstance:
    403     ReceiverType = E->getSuperType();
    404     Receiver = LoadObjCSelf();
    405     isSuperMessage = true;
    406     break;
    407 
    408   case ObjCMessageExpr::SuperClass:
    409     ReceiverType = E->getSuperType();
    410     Receiver = LoadObjCSelf();
    411     isSuperMessage = true;
    412     isClassMessage = true;
    413     break;
    414   }
    415 
    416   if (retainSelf)
    417     Receiver = EmitARCRetainNonBlock(Receiver);
    418 
    419   // In ARC, we sometimes want to "extend the lifetime"
    420   // (i.e. retain+autorelease) of receivers of returns-inner-pointer
    421   // messages.
    422   if (getLangOpts().ObjCAutoRefCount && method &&
    423       method->hasAttr<ObjCReturnsInnerPointerAttr>() &&
    424       shouldExtendReceiverForInnerPointerMessage(E))
    425     Receiver = EmitARCRetainAutorelease(ReceiverType, Receiver);
    426 
    427   QualType ResultType = method ? method->getReturnType() : E->getType();
    428 
    429   CallArgList Args;
    430   EmitCallArgs(Args, method, E->arguments());
    431 
    432   // For delegate init calls in ARC, do an unsafe store of null into
    433   // self.  This represents the call taking direct ownership of that
    434   // value.  We have to do this after emitting the other call
    435   // arguments because they might also reference self, but we don't
    436   // have to worry about any of them modifying self because that would
    437   // be an undefined read and write of an object in unordered
    438   // expressions.
    439   if (isDelegateInit) {
    440     assert(getLangOpts().ObjCAutoRefCount &&
    441            "delegate init calls should only be marked in ARC");
    442 
    443     // Do an unsafe store of null into self.
    444     Address selfAddr =
    445       GetAddrOfLocalVar(cast<ObjCMethodDecl>(CurCodeDecl)->getSelfDecl());
    446     Builder.CreateStore(getNullForVariable(selfAddr), selfAddr);
    447   }
    448 
    449   RValue result;
    450   if (isSuperMessage) {
    451     // super is only valid in an Objective-C method
    452     const ObjCMethodDecl *OMD = cast<ObjCMethodDecl>(CurFuncDecl);
    453     bool isCategoryImpl = isa<ObjCCategoryImplDecl>(OMD->getDeclContext());
    454     result = Runtime.GenerateMessageSendSuper(*this, Return, ResultType,
    455                                               E->getSelector(),
    456                                               OMD->getClassInterface(),
    457                                               isCategoryImpl,
    458                                               Receiver,
    459                                               isClassMessage,
    460                                               Args,
    461                                               method);
    462   } else {
    463     result = Runtime.GenerateMessageSend(*this, Return, ResultType,
    464                                          E->getSelector(),
    465                                          Receiver, Args, OID,
    466                                          method);
    467   }
    468 
    469   // For delegate init calls in ARC, implicitly store the result of
    470   // the call back into self.  This takes ownership of the value.
    471   if (isDelegateInit) {
    472     Address selfAddr =
    473       GetAddrOfLocalVar(cast<ObjCMethodDecl>(CurCodeDecl)->getSelfDecl());
    474     llvm::Value *newSelf = result.getScalarVal();
    475 
    476     // The delegate return type isn't necessarily a matching type; in
    477     // fact, it's quite likely to be 'id'.
    478     llvm::Type *selfTy = selfAddr.getElementType();
    479     newSelf = Builder.CreateBitCast(newSelf, selfTy);
    480 
    481     Builder.CreateStore(newSelf, selfAddr);
    482   }
    483 
    484   return AdjustObjCObjectType(*this, E->getType(), result);
    485 }
    486 
    487 namespace {
    488 struct FinishARCDealloc final : EHScopeStack::Cleanup {
    489   void Emit(CodeGenFunction &CGF, Flags flags) override {
    490     const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CGF.CurCodeDecl);
    491 
    492     const ObjCImplDecl *impl = cast<ObjCImplDecl>(method->getDeclContext());
    493     const ObjCInterfaceDecl *iface = impl->getClassInterface();
    494     if (!iface->getSuperClass()) return;
    495 
    496     bool isCategory = isa<ObjCCategoryImplDecl>(impl);
    497 
    498     // Call [super dealloc] if we have a superclass.
    499     llvm::Value *self = CGF.LoadObjCSelf();
    500 
    501     CallArgList args;
    502     CGF.CGM.getObjCRuntime().GenerateMessageSendSuper(CGF, ReturnValueSlot(),
    503                                                       CGF.getContext().VoidTy,
    504                                                       method->getSelector(),
    505                                                       iface,
    506                                                       isCategory,
    507                                                       self,
    508                                                       /*is class msg*/ false,
    509                                                       args,
    510                                                       method);
    511   }
    512 };
    513 }
    514 
    515 /// StartObjCMethod - Begin emission of an ObjCMethod. This generates
    516 /// the LLVM function and sets the other context used by
    517 /// CodeGenFunction.
    518 void CodeGenFunction::StartObjCMethod(const ObjCMethodDecl *OMD,
    519                                       const ObjCContainerDecl *CD) {
    520   SourceLocation StartLoc = OMD->getLocStart();
    521   FunctionArgList args;
    522   // Check if we should generate debug info for this method.
    523   if (OMD->hasAttr<NoDebugAttr>())
    524     DebugInfo = nullptr; // disable debug info indefinitely for this function
    525 
    526   llvm::Function *Fn = CGM.getObjCRuntime().GenerateMethod(OMD, CD);
    527 
    528   const CGFunctionInfo &FI = CGM.getTypes().arrangeObjCMethodDeclaration(OMD);
    529   CGM.SetInternalFunctionAttributes(OMD, Fn, FI);
    530 
    531   args.push_back(OMD->getSelfDecl());
    532   args.push_back(OMD->getCmdDecl());
    533 
    534   args.append(OMD->param_begin(), OMD->param_end());
    535 
    536   CurGD = OMD;
    537   CurEHLocation = OMD->getLocEnd();
    538 
    539   StartFunction(OMD, OMD->getReturnType(), Fn, FI, args,
    540                 OMD->getLocation(), StartLoc);
    541 
    542   // In ARC, certain methods get an extra cleanup.
    543   if (CGM.getLangOpts().ObjCAutoRefCount &&
    544       OMD->isInstanceMethod() &&
    545       OMD->getSelector().isUnarySelector()) {
    546     const IdentifierInfo *ident =
    547       OMD->getSelector().getIdentifierInfoForSlot(0);
    548     if (ident->isStr("dealloc"))
    549       EHStack.pushCleanup<FinishARCDealloc>(getARCCleanupKind());
    550   }
    551 }
    552 
    553 static llvm::Value *emitARCRetainLoadOfScalar(CodeGenFunction &CGF,
    554                                               LValue lvalue, QualType type);
    555 
    556 /// Generate an Objective-C method.  An Objective-C method is a C function with
    557 /// its pointer, name, and types registered in the class struture.
    558 void CodeGenFunction::GenerateObjCMethod(const ObjCMethodDecl *OMD) {
    559   StartObjCMethod(OMD, OMD->getClassInterface());
    560   PGO.assignRegionCounters(GlobalDecl(OMD), CurFn);
    561   assert(isa<CompoundStmt>(OMD->getBody()));
    562   incrementProfileCounter(OMD->getBody());
    563   EmitCompoundStmtWithoutScope(*cast<CompoundStmt>(OMD->getBody()));
    564   FinishFunction(OMD->getBodyRBrace());
    565 }
    566 
    567 /// emitStructGetterCall - Call the runtime function to load a property
    568 /// into the return value slot.
    569 static void emitStructGetterCall(CodeGenFunction &CGF, ObjCIvarDecl *ivar,
    570                                  bool isAtomic, bool hasStrong) {
    571   ASTContext &Context = CGF.getContext();
    572 
    573   Address src =
    574     CGF.EmitLValueForIvar(CGF.TypeOfSelfObject(), CGF.LoadObjCSelf(), ivar, 0)
    575        .getAddress();
    576 
    577   // objc_copyStruct (ReturnValue, &structIvar,
    578   //                  sizeof (Type of Ivar), isAtomic, false);
    579   CallArgList args;
    580 
    581   Address dest = CGF.Builder.CreateBitCast(CGF.ReturnValue, CGF.VoidPtrTy);
    582   args.add(RValue::get(dest.getPointer()), Context.VoidPtrTy);
    583 
    584   src = CGF.Builder.CreateBitCast(src, CGF.VoidPtrTy);
    585   args.add(RValue::get(src.getPointer()), Context.VoidPtrTy);
    586 
    587   CharUnits size = CGF.getContext().getTypeSizeInChars(ivar->getType());
    588   args.add(RValue::get(CGF.CGM.getSize(size)), Context.getSizeType());
    589   args.add(RValue::get(CGF.Builder.getInt1(isAtomic)), Context.BoolTy);
    590   args.add(RValue::get(CGF.Builder.getInt1(hasStrong)), Context.BoolTy);
    591 
    592   llvm::Value *fn = CGF.CGM.getObjCRuntime().GetGetStructFunction();
    593   CGF.EmitCall(CGF.getTypes().arrangeBuiltinFunctionCall(Context.VoidTy, args),
    594                fn, ReturnValueSlot(), args);
    595 }
    596 
    597 /// Determine whether the given architecture supports unaligned atomic
    598 /// accesses.  They don't have to be fast, just faster than a function
    599 /// call and a mutex.
    600 static bool hasUnalignedAtomics(llvm::Triple::ArchType arch) {
    601   // FIXME: Allow unaligned atomic load/store on x86.  (It is not
    602   // currently supported by the backend.)
    603   return 0;
    604 }
    605 
    606 /// Return the maximum size that permits atomic accesses for the given
    607 /// architecture.
    608 static CharUnits getMaxAtomicAccessSize(CodeGenModule &CGM,
    609                                         llvm::Triple::ArchType arch) {
    610   // ARM has 8-byte atomic accesses, but it's not clear whether we
    611   // want to rely on them here.
    612 
    613   // In the default case, just assume that any size up to a pointer is
    614   // fine given adequate alignment.
    615   return CharUnits::fromQuantity(CGM.PointerSizeInBytes);
    616 }
    617 
    618 namespace {
    619   class PropertyImplStrategy {
    620   public:
    621     enum StrategyKind {
    622       /// The 'native' strategy is to use the architecture's provided
    623       /// reads and writes.
    624       Native,
    625 
    626       /// Use objc_setProperty and objc_getProperty.
    627       GetSetProperty,
    628 
    629       /// Use objc_setProperty for the setter, but use expression
    630       /// evaluation for the getter.
    631       SetPropertyAndExpressionGet,
    632 
    633       /// Use objc_copyStruct.
    634       CopyStruct,
    635 
    636       /// The 'expression' strategy is to emit normal assignment or
    637       /// lvalue-to-rvalue expressions.
    638       Expression
    639     };
    640 
    641     StrategyKind getKind() const { return StrategyKind(Kind); }
    642 
    643     bool hasStrongMember() const { return HasStrong; }
    644     bool isAtomic() const { return IsAtomic; }
    645     bool isCopy() const { return IsCopy; }
    646 
    647     CharUnits getIvarSize() const { return IvarSize; }
    648     CharUnits getIvarAlignment() const { return IvarAlignment; }
    649 
    650     PropertyImplStrategy(CodeGenModule &CGM,
    651                          const ObjCPropertyImplDecl *propImpl);
    652 
    653   private:
    654     unsigned Kind : 8;
    655     unsigned IsAtomic : 1;
    656     unsigned IsCopy : 1;
    657     unsigned HasStrong : 1;
    658 
    659     CharUnits IvarSize;
    660     CharUnits IvarAlignment;
    661   };
    662 }
    663 
    664 /// Pick an implementation strategy for the given property synthesis.
    665 PropertyImplStrategy::PropertyImplStrategy(CodeGenModule &CGM,
    666                                      const ObjCPropertyImplDecl *propImpl) {
    667   const ObjCPropertyDecl *prop = propImpl->getPropertyDecl();
    668   ObjCPropertyDecl::SetterKind setterKind = prop->getSetterKind();
    669 
    670   IsCopy = (setterKind == ObjCPropertyDecl::Copy);
    671   IsAtomic = prop->isAtomic();
    672   HasStrong = false; // doesn't matter here.
    673 
    674   // Evaluate the ivar's size and alignment.
    675   ObjCIvarDecl *ivar = propImpl->getPropertyIvarDecl();
    676   QualType ivarType = ivar->getType();
    677   std::tie(IvarSize, IvarAlignment) =
    678       CGM.getContext().getTypeInfoInChars(ivarType);
    679 
    680   // If we have a copy property, we always have to use getProperty/setProperty.
    681   // TODO: we could actually use setProperty and an expression for non-atomics.
    682   if (IsCopy) {
    683     Kind = GetSetProperty;
    684     return;
    685   }
    686 
    687   // Handle retain.
    688   if (setterKind == ObjCPropertyDecl::Retain) {
    689     // In GC-only, there's nothing special that needs to be done.
    690     if (CGM.getLangOpts().getGC() == LangOptions::GCOnly) {
    691       // fallthrough
    692 
    693     // In ARC, if the property is non-atomic, use expression emission,
    694     // which translates to objc_storeStrong.  This isn't required, but
    695     // it's slightly nicer.
    696     } else if (CGM.getLangOpts().ObjCAutoRefCount && !IsAtomic) {
    697       // Using standard expression emission for the setter is only
    698       // acceptable if the ivar is __strong, which won't be true if
    699       // the property is annotated with __attribute__((NSObject)).
    700       // TODO: falling all the way back to objc_setProperty here is
    701       // just laziness, though;  we could still use objc_storeStrong
    702       // if we hacked it right.
    703       if (ivarType.getObjCLifetime() == Qualifiers::OCL_Strong)
    704         Kind = Expression;
    705       else
    706         Kind = SetPropertyAndExpressionGet;
    707       return;
    708 
    709     // Otherwise, we need to at least use setProperty.  However, if
    710     // the property isn't atomic, we can use normal expression
    711     // emission for the getter.
    712     } else if (!IsAtomic) {
    713       Kind = SetPropertyAndExpressionGet;
    714       return;
    715 
    716     // Otherwise, we have to use both setProperty and getProperty.
    717     } else {
    718       Kind = GetSetProperty;
    719       return;
    720     }
    721   }
    722 
    723   // If we're not atomic, just use expression accesses.
    724   if (!IsAtomic) {
    725     Kind = Expression;
    726     return;
    727   }
    728 
    729   // Properties on bitfield ivars need to be emitted using expression
    730   // accesses even if they're nominally atomic.
    731   if (ivar->isBitField()) {
    732     Kind = Expression;
    733     return;
    734   }
    735 
    736   // GC-qualified or ARC-qualified ivars need to be emitted as
    737   // expressions.  This actually works out to being atomic anyway,
    738   // except for ARC __strong, but that should trigger the above code.
    739   if (ivarType.hasNonTrivialObjCLifetime() ||
    740       (CGM.getLangOpts().getGC() &&
    741        CGM.getContext().getObjCGCAttrKind(ivarType))) {
    742     Kind = Expression;
    743     return;
    744   }
    745 
    746   // Compute whether the ivar has strong members.
    747   if (CGM.getLangOpts().getGC())
    748     if (const RecordType *recordType = ivarType->getAs<RecordType>())
    749       HasStrong = recordType->getDecl()->hasObjectMember();
    750 
    751   // We can never access structs with object members with a native
    752   // access, because we need to use write barriers.  This is what
    753   // objc_copyStruct is for.
    754   if (HasStrong) {
    755     Kind = CopyStruct;
    756     return;
    757   }
    758 
    759   // Otherwise, this is target-dependent and based on the size and
    760   // alignment of the ivar.
    761 
    762   // If the size of the ivar is not a power of two, give up.  We don't
    763   // want to get into the business of doing compare-and-swaps.
    764   if (!IvarSize.isPowerOfTwo()) {
    765     Kind = CopyStruct;
    766     return;
    767   }
    768 
    769   llvm::Triple::ArchType arch =
    770     CGM.getTarget().getTriple().getArch();
    771 
    772   // Most architectures require memory to fit within a single cache
    773   // line, so the alignment has to be at least the size of the access.
    774   // Otherwise we have to grab a lock.
    775   if (IvarAlignment < IvarSize && !hasUnalignedAtomics(arch)) {
    776     Kind = CopyStruct;
    777     return;
    778   }
    779 
    780   // If the ivar's size exceeds the architecture's maximum atomic
    781   // access size, we have to use CopyStruct.
    782   if (IvarSize > getMaxAtomicAccessSize(CGM, arch)) {
    783     Kind = CopyStruct;
    784     return;
    785   }
    786 
    787   // Otherwise, we can use native loads and stores.
    788   Kind = Native;
    789 }
    790 
    791 /// \brief Generate an Objective-C property getter function.
    792 ///
    793 /// The given Decl must be an ObjCImplementationDecl. \@synthesize
    794 /// is illegal within a category.
    795 void CodeGenFunction::GenerateObjCGetter(ObjCImplementationDecl *IMP,
    796                                          const ObjCPropertyImplDecl *PID) {
    797   llvm::Constant *AtomicHelperFn =
    798       CodeGenFunction(CGM).GenerateObjCAtomicGetterCopyHelperFunction(PID);
    799   const ObjCPropertyDecl *PD = PID->getPropertyDecl();
    800   ObjCMethodDecl *OMD = PD->getGetterMethodDecl();
    801   assert(OMD && "Invalid call to generate getter (empty method)");
    802   StartObjCMethod(OMD, IMP->getClassInterface());
    803 
    804   generateObjCGetterBody(IMP, PID, OMD, AtomicHelperFn);
    805 
    806   FinishFunction();
    807 }
    808 
    809 static bool hasTrivialGetExpr(const ObjCPropertyImplDecl *propImpl) {
    810   const Expr *getter = propImpl->getGetterCXXConstructor();
    811   if (!getter) return true;
    812 
    813   // Sema only makes only of these when the ivar has a C++ class type,
    814   // so the form is pretty constrained.
    815 
    816   // If the property has a reference type, we might just be binding a
    817   // reference, in which case the result will be a gl-value.  We should
    818   // treat this as a non-trivial operation.
    819   if (getter->isGLValue())
    820     return false;
    821 
    822   // If we selected a trivial copy-constructor, we're okay.
    823   if (const CXXConstructExpr *construct = dyn_cast<CXXConstructExpr>(getter))
    824     return (construct->getConstructor()->isTrivial());
    825 
    826   // The constructor might require cleanups (in which case it's never
    827   // trivial).
    828   assert(isa<ExprWithCleanups>(getter));
    829   return false;
    830 }
    831 
    832 /// emitCPPObjectAtomicGetterCall - Call the runtime function to
    833 /// copy the ivar into the resturn slot.
    834 static void emitCPPObjectAtomicGetterCall(CodeGenFunction &CGF,
    835                                           llvm::Value *returnAddr,
    836                                           ObjCIvarDecl *ivar,
    837                                           llvm::Constant *AtomicHelperFn) {
    838   // objc_copyCppObjectAtomic (&returnSlot, &CppObjectIvar,
    839   //                           AtomicHelperFn);
    840   CallArgList args;
    841 
    842   // The 1st argument is the return Slot.
    843   args.add(RValue::get(returnAddr), CGF.getContext().VoidPtrTy);
    844 
    845   // The 2nd argument is the address of the ivar.
    846   llvm::Value *ivarAddr =
    847     CGF.EmitLValueForIvar(CGF.TypeOfSelfObject(),
    848                           CGF.LoadObjCSelf(), ivar, 0).getPointer();
    849   ivarAddr = CGF.Builder.CreateBitCast(ivarAddr, CGF.Int8PtrTy);
    850   args.add(RValue::get(ivarAddr), CGF.getContext().VoidPtrTy);
    851 
    852   // Third argument is the helper function.
    853   args.add(RValue::get(AtomicHelperFn), CGF.getContext().VoidPtrTy);
    854 
    855   llvm::Value *copyCppAtomicObjectFn =
    856     CGF.CGM.getObjCRuntime().GetCppAtomicObjectGetFunction();
    857   CGF.EmitCall(
    858       CGF.getTypes().arrangeBuiltinFunctionCall(CGF.getContext().VoidTy, args),
    859                copyCppAtomicObjectFn, ReturnValueSlot(), args);
    860 }
    861 
    862 void
    863 CodeGenFunction::generateObjCGetterBody(const ObjCImplementationDecl *classImpl,
    864                                         const ObjCPropertyImplDecl *propImpl,
    865                                         const ObjCMethodDecl *GetterMethodDecl,
    866                                         llvm::Constant *AtomicHelperFn) {
    867   // If there's a non-trivial 'get' expression, we just have to emit that.
    868   if (!hasTrivialGetExpr(propImpl)) {
    869     if (!AtomicHelperFn) {
    870       ReturnStmt ret(SourceLocation(), propImpl->getGetterCXXConstructor(),
    871                      /*nrvo*/ nullptr);
    872       EmitReturnStmt(ret);
    873     }
    874     else {
    875       ObjCIvarDecl *ivar = propImpl->getPropertyIvarDecl();
    876       emitCPPObjectAtomicGetterCall(*this, ReturnValue.getPointer(),
    877                                     ivar, AtomicHelperFn);
    878     }
    879     return;
    880   }
    881 
    882   const ObjCPropertyDecl *prop = propImpl->getPropertyDecl();
    883   QualType propType = prop->getType();
    884   ObjCMethodDecl *getterMethod = prop->getGetterMethodDecl();
    885 
    886   ObjCIvarDecl *ivar = propImpl->getPropertyIvarDecl();
    887 
    888   // Pick an implementation strategy.
    889   PropertyImplStrategy strategy(CGM, propImpl);
    890   switch (strategy.getKind()) {
    891   case PropertyImplStrategy::Native: {
    892     // We don't need to do anything for a zero-size struct.
    893     if (strategy.getIvarSize().isZero())
    894       return;
    895 
    896     LValue LV = EmitLValueForIvar(TypeOfSelfObject(), LoadObjCSelf(), ivar, 0);
    897 
    898     // Currently, all atomic accesses have to be through integer
    899     // types, so there's no point in trying to pick a prettier type.
    900     uint64_t ivarSize = getContext().toBits(strategy.getIvarSize());
    901     llvm::Type *bitcastType = llvm::Type::getIntNTy(getLLVMContext(), ivarSize);
    902     bitcastType = bitcastType->getPointerTo(); // addrspace 0 okay
    903 
    904     // Perform an atomic load.  This does not impose ordering constraints.
    905     Address ivarAddr = LV.getAddress();
    906     ivarAddr = Builder.CreateBitCast(ivarAddr, bitcastType);
    907     llvm::LoadInst *load = Builder.CreateLoad(ivarAddr, "load");
    908     load->setAtomic(llvm::AtomicOrdering::Unordered);
    909 
    910     // Store that value into the return address.  Doing this with a
    911     // bitcast is likely to produce some pretty ugly IR, but it's not
    912     // the *most* terrible thing in the world.
    913     llvm::Type *retTy = ConvertType(getterMethod->getReturnType());
    914     uint64_t retTySize = CGM.getDataLayout().getTypeSizeInBits(retTy);
    915     llvm::Value *ivarVal = load;
    916     if (ivarSize > retTySize) {
    917       llvm::Type *newTy = llvm::Type::getIntNTy(getLLVMContext(), retTySize);
    918       ivarVal = Builder.CreateTrunc(load, newTy);
    919       bitcastType = newTy->getPointerTo();
    920     }
    921     Builder.CreateStore(ivarVal,
    922                         Builder.CreateBitCast(ReturnValue, bitcastType));
    923 
    924     // Make sure we don't do an autorelease.
    925     AutoreleaseResult = false;
    926     return;
    927   }
    928 
    929   case PropertyImplStrategy::GetSetProperty: {
    930     llvm::Value *getPropertyFn =
    931       CGM.getObjCRuntime().GetPropertyGetFunction();
    932     if (!getPropertyFn) {
    933       CGM.ErrorUnsupported(propImpl, "Obj-C getter requiring atomic copy");
    934       return;
    935     }
    936 
    937     // Return (ivar-type) objc_getProperty((id) self, _cmd, offset, true).
    938     // FIXME: Can't this be simpler? This might even be worse than the
    939     // corresponding gcc code.
    940     llvm::Value *cmd =
    941       Builder.CreateLoad(GetAddrOfLocalVar(getterMethod->getCmdDecl()), "cmd");
    942     llvm::Value *self = Builder.CreateBitCast(LoadObjCSelf(), VoidPtrTy);
    943     llvm::Value *ivarOffset =
    944       EmitIvarOffset(classImpl->getClassInterface(), ivar);
    945 
    946     CallArgList args;
    947     args.add(RValue::get(self), getContext().getObjCIdType());
    948     args.add(RValue::get(cmd), getContext().getObjCSelType());
    949     args.add(RValue::get(ivarOffset), getContext().getPointerDiffType());
    950     args.add(RValue::get(Builder.getInt1(strategy.isAtomic())),
    951              getContext().BoolTy);
    952 
    953     // FIXME: We shouldn't need to get the function info here, the
    954     // runtime already should have computed it to build the function.
    955     llvm::Instruction *CallInstruction;
    956     RValue RV = EmitCall(
    957         getTypes().arrangeBuiltinFunctionCall(propType, args),
    958         getPropertyFn, ReturnValueSlot(), args, CGCalleeInfo(),
    959         &CallInstruction);
    960     if (llvm::CallInst *call = dyn_cast<llvm::CallInst>(CallInstruction))
    961       call->setTailCall();
    962 
    963     // We need to fix the type here. Ivars with copy & retain are
    964     // always objects so we don't need to worry about complex or
    965     // aggregates.
    966     RV = RValue::get(Builder.CreateBitCast(
    967         RV.getScalarVal(),
    968         getTypes().ConvertType(getterMethod->getReturnType())));
    969 
    970     EmitReturnOfRValue(RV, propType);
    971 
    972     // objc_getProperty does an autorelease, so we should suppress ours.
    973     AutoreleaseResult = false;
    974 
    975     return;
    976   }
    977 
    978   case PropertyImplStrategy::CopyStruct:
    979     emitStructGetterCall(*this, ivar, strategy.isAtomic(),
    980                          strategy.hasStrongMember());
    981     return;
    982 
    983   case PropertyImplStrategy::Expression:
    984   case PropertyImplStrategy::SetPropertyAndExpressionGet: {
    985     LValue LV = EmitLValueForIvar(TypeOfSelfObject(), LoadObjCSelf(), ivar, 0);
    986 
    987     QualType ivarType = ivar->getType();
    988     switch (getEvaluationKind(ivarType)) {
    989     case TEK_Complex: {
    990       ComplexPairTy pair = EmitLoadOfComplex(LV, SourceLocation());
    991       EmitStoreOfComplex(pair, MakeAddrLValue(ReturnValue, ivarType),
    992                          /*init*/ true);
    993       return;
    994     }
    995     case TEK_Aggregate:
    996       // The return value slot is guaranteed to not be aliased, but
    997       // that's not necessarily the same as "on the stack", so
    998       // we still potentially need objc_memmove_collectable.
    999       EmitAggregateCopy(ReturnValue, LV.getAddress(), ivarType);
   1000       return;
   1001     case TEK_Scalar: {
   1002       llvm::Value *value;
   1003       if (propType->isReferenceType()) {
   1004         value = LV.getAddress().getPointer();
   1005       } else {
   1006         // We want to load and autoreleaseReturnValue ARC __weak ivars.
   1007         if (LV.getQuals().getObjCLifetime() == Qualifiers::OCL_Weak) {
   1008           if (getLangOpts().ObjCAutoRefCount) {
   1009             value = emitARCRetainLoadOfScalar(*this, LV, ivarType);
   1010           } else {
   1011             value = EmitARCLoadWeak(LV.getAddress());
   1012           }
   1013 
   1014         // Otherwise we want to do a simple load, suppressing the
   1015         // final autorelease.
   1016         } else {
   1017           value = EmitLoadOfLValue(LV, SourceLocation()).getScalarVal();
   1018           AutoreleaseResult = false;
   1019         }
   1020 
   1021         value = Builder.CreateBitCast(
   1022             value, ConvertType(GetterMethodDecl->getReturnType()));
   1023       }
   1024 
   1025       EmitReturnOfRValue(RValue::get(value), propType);
   1026       return;
   1027     }
   1028     }
   1029     llvm_unreachable("bad evaluation kind");
   1030   }
   1031 
   1032   }
   1033   llvm_unreachable("bad @property implementation strategy!");
   1034 }
   1035 
   1036 /// emitStructSetterCall - Call the runtime function to store the value
   1037 /// from the first formal parameter into the given ivar.
   1038 static void emitStructSetterCall(CodeGenFunction &CGF, ObjCMethodDecl *OMD,
   1039                                  ObjCIvarDecl *ivar) {
   1040   // objc_copyStruct (&structIvar, &Arg,
   1041   //                  sizeof (struct something), true, false);
   1042   CallArgList args;
   1043 
   1044   // The first argument is the address of the ivar.
   1045   llvm::Value *ivarAddr = CGF.EmitLValueForIvar(CGF.TypeOfSelfObject(),
   1046                                                 CGF.LoadObjCSelf(), ivar, 0)
   1047     .getPointer();
   1048   ivarAddr = CGF.Builder.CreateBitCast(ivarAddr, CGF.Int8PtrTy);
   1049   args.add(RValue::get(ivarAddr), CGF.getContext().VoidPtrTy);
   1050 
   1051   // The second argument is the address of the parameter variable.
   1052   ParmVarDecl *argVar = *OMD->param_begin();
   1053   DeclRefExpr argRef(argVar, false, argVar->getType().getNonReferenceType(),
   1054                      VK_LValue, SourceLocation());
   1055   llvm::Value *argAddr = CGF.EmitLValue(&argRef).getPointer();
   1056   argAddr = CGF.Builder.CreateBitCast(argAddr, CGF.Int8PtrTy);
   1057   args.add(RValue::get(argAddr), CGF.getContext().VoidPtrTy);
   1058 
   1059   // The third argument is the sizeof the type.
   1060   llvm::Value *size =
   1061     CGF.CGM.getSize(CGF.getContext().getTypeSizeInChars(ivar->getType()));
   1062   args.add(RValue::get(size), CGF.getContext().getSizeType());
   1063 
   1064   // The fourth argument is the 'isAtomic' flag.
   1065   args.add(RValue::get(CGF.Builder.getTrue()), CGF.getContext().BoolTy);
   1066 
   1067   // The fifth argument is the 'hasStrong' flag.
   1068   // FIXME: should this really always be false?
   1069   args.add(RValue::get(CGF.Builder.getFalse()), CGF.getContext().BoolTy);
   1070 
   1071   llvm::Value *copyStructFn = CGF.CGM.getObjCRuntime().GetSetStructFunction();
   1072   CGF.EmitCall(
   1073       CGF.getTypes().arrangeBuiltinFunctionCall(CGF.getContext().VoidTy, args),
   1074                copyStructFn, ReturnValueSlot(), args);
   1075 }
   1076 
   1077 /// emitCPPObjectAtomicSetterCall - Call the runtime function to store
   1078 /// the value from the first formal parameter into the given ivar, using
   1079 /// the Cpp API for atomic Cpp objects with non-trivial copy assignment.
   1080 static void emitCPPObjectAtomicSetterCall(CodeGenFunction &CGF,
   1081                                           ObjCMethodDecl *OMD,
   1082                                           ObjCIvarDecl *ivar,
   1083                                           llvm::Constant *AtomicHelperFn) {
   1084   // objc_copyCppObjectAtomic (&CppObjectIvar, &Arg,
   1085   //                           AtomicHelperFn);
   1086   CallArgList args;
   1087 
   1088   // The first argument is the address of the ivar.
   1089   llvm::Value *ivarAddr =
   1090     CGF.EmitLValueForIvar(CGF.TypeOfSelfObject(),
   1091                           CGF.LoadObjCSelf(), ivar, 0).getPointer();
   1092   ivarAddr = CGF.Builder.CreateBitCast(ivarAddr, CGF.Int8PtrTy);
   1093   args.add(RValue::get(ivarAddr), CGF.getContext().VoidPtrTy);
   1094 
   1095   // The second argument is the address of the parameter variable.
   1096   ParmVarDecl *argVar = *OMD->param_begin();
   1097   DeclRefExpr argRef(argVar, false, argVar->getType().getNonReferenceType(),
   1098                      VK_LValue, SourceLocation());
   1099   llvm::Value *argAddr = CGF.EmitLValue(&argRef).getPointer();
   1100   argAddr = CGF.Builder.CreateBitCast(argAddr, CGF.Int8PtrTy);
   1101   args.add(RValue::get(argAddr), CGF.getContext().VoidPtrTy);
   1102 
   1103   // Third argument is the helper function.
   1104   args.add(RValue::get(AtomicHelperFn), CGF.getContext().VoidPtrTy);
   1105 
   1106   llvm::Value *copyCppAtomicObjectFn =
   1107     CGF.CGM.getObjCRuntime().GetCppAtomicObjectSetFunction();
   1108   CGF.EmitCall(
   1109       CGF.getTypes().arrangeBuiltinFunctionCall(CGF.getContext().VoidTy, args),
   1110                copyCppAtomicObjectFn, ReturnValueSlot(), args);
   1111 }
   1112 
   1113 
   1114 static bool hasTrivialSetExpr(const ObjCPropertyImplDecl *PID) {
   1115   Expr *setter = PID->getSetterCXXAssignment();
   1116   if (!setter) return true;
   1117 
   1118   // Sema only makes only of these when the ivar has a C++ class type,
   1119   // so the form is pretty constrained.
   1120 
   1121   // An operator call is trivial if the function it calls is trivial.
   1122   // This also implies that there's nothing non-trivial going on with
   1123   // the arguments, because operator= can only be trivial if it's a
   1124   // synthesized assignment operator and therefore both parameters are
   1125   // references.
   1126   if (CallExpr *call = dyn_cast<CallExpr>(setter)) {
   1127     if (const FunctionDecl *callee
   1128           = dyn_cast_or_null<FunctionDecl>(call->getCalleeDecl()))
   1129       if (callee->isTrivial())
   1130         return true;
   1131     return false;
   1132   }
   1133 
   1134   assert(isa<ExprWithCleanups>(setter));
   1135   return false;
   1136 }
   1137 
   1138 static bool UseOptimizedSetter(CodeGenModule &CGM) {
   1139   if (CGM.getLangOpts().getGC() != LangOptions::NonGC)
   1140     return false;
   1141   return CGM.getLangOpts().ObjCRuntime.hasOptimizedSetter();
   1142 }
   1143 
   1144 void
   1145 CodeGenFunction::generateObjCSetterBody(const ObjCImplementationDecl *classImpl,
   1146                                         const ObjCPropertyImplDecl *propImpl,
   1147                                         llvm::Constant *AtomicHelperFn) {
   1148   const ObjCPropertyDecl *prop = propImpl->getPropertyDecl();
   1149   ObjCIvarDecl *ivar = propImpl->getPropertyIvarDecl();
   1150   ObjCMethodDecl *setterMethod = prop->getSetterMethodDecl();
   1151 
   1152   // Just use the setter expression if Sema gave us one and it's
   1153   // non-trivial.
   1154   if (!hasTrivialSetExpr(propImpl)) {
   1155     if (!AtomicHelperFn)
   1156       // If non-atomic, assignment is called directly.
   1157       EmitStmt(propImpl->getSetterCXXAssignment());
   1158     else
   1159       // If atomic, assignment is called via a locking api.
   1160       emitCPPObjectAtomicSetterCall(*this, setterMethod, ivar,
   1161                                     AtomicHelperFn);
   1162     return;
   1163   }
   1164 
   1165   PropertyImplStrategy strategy(CGM, propImpl);
   1166   switch (strategy.getKind()) {
   1167   case PropertyImplStrategy::Native: {
   1168     // We don't need to do anything for a zero-size struct.
   1169     if (strategy.getIvarSize().isZero())
   1170       return;
   1171 
   1172     Address argAddr = GetAddrOfLocalVar(*setterMethod->param_begin());
   1173 
   1174     LValue ivarLValue =
   1175       EmitLValueForIvar(TypeOfSelfObject(), LoadObjCSelf(), ivar, /*quals*/ 0);
   1176     Address ivarAddr = ivarLValue.getAddress();
   1177 
   1178     // Currently, all atomic accesses have to be through integer
   1179     // types, so there's no point in trying to pick a prettier type.
   1180     llvm::Type *bitcastType =
   1181       llvm::Type::getIntNTy(getLLVMContext(),
   1182                             getContext().toBits(strategy.getIvarSize()));
   1183 
   1184     // Cast both arguments to the chosen operation type.
   1185     argAddr = Builder.CreateElementBitCast(argAddr, bitcastType);
   1186     ivarAddr = Builder.CreateElementBitCast(ivarAddr, bitcastType);
   1187 
   1188     // This bitcast load is likely to cause some nasty IR.
   1189     llvm::Value *load = Builder.CreateLoad(argAddr);
   1190 
   1191     // Perform an atomic store.  There are no memory ordering requirements.
   1192     llvm::StoreInst *store = Builder.CreateStore(load, ivarAddr);
   1193     store->setAtomic(llvm::AtomicOrdering::Unordered);
   1194     return;
   1195   }
   1196 
   1197   case PropertyImplStrategy::GetSetProperty:
   1198   case PropertyImplStrategy::SetPropertyAndExpressionGet: {
   1199 
   1200     llvm::Value *setOptimizedPropertyFn = nullptr;
   1201     llvm::Value *setPropertyFn = nullptr;
   1202     if (UseOptimizedSetter(CGM)) {
   1203       // 10.8 and iOS 6.0 code and GC is off
   1204       setOptimizedPropertyFn =
   1205         CGM.getObjCRuntime()
   1206            .GetOptimizedPropertySetFunction(strategy.isAtomic(),
   1207                                             strategy.isCopy());
   1208       if (!setOptimizedPropertyFn) {
   1209         CGM.ErrorUnsupported(propImpl, "Obj-C optimized setter - NYI");
   1210         return;
   1211       }
   1212     }
   1213     else {
   1214       setPropertyFn = CGM.getObjCRuntime().GetPropertySetFunction();
   1215       if (!setPropertyFn) {
   1216         CGM.ErrorUnsupported(propImpl, "Obj-C setter requiring atomic copy");
   1217         return;
   1218       }
   1219     }
   1220 
   1221     // Emit objc_setProperty((id) self, _cmd, offset, arg,
   1222     //                       <is-atomic>, <is-copy>).
   1223     llvm::Value *cmd =
   1224       Builder.CreateLoad(GetAddrOfLocalVar(setterMethod->getCmdDecl()));
   1225     llvm::Value *self =
   1226       Builder.CreateBitCast(LoadObjCSelf(), VoidPtrTy);
   1227     llvm::Value *ivarOffset =
   1228       EmitIvarOffset(classImpl->getClassInterface(), ivar);
   1229     Address argAddr = GetAddrOfLocalVar(*setterMethod->param_begin());
   1230     llvm::Value *arg = Builder.CreateLoad(argAddr, "arg");
   1231     arg = Builder.CreateBitCast(arg, VoidPtrTy);
   1232 
   1233     CallArgList args;
   1234     args.add(RValue::get(self), getContext().getObjCIdType());
   1235     args.add(RValue::get(cmd), getContext().getObjCSelType());
   1236     if (setOptimizedPropertyFn) {
   1237       args.add(RValue::get(arg), getContext().getObjCIdType());
   1238       args.add(RValue::get(ivarOffset), getContext().getPointerDiffType());
   1239       EmitCall(getTypes().arrangeBuiltinFunctionCall(getContext().VoidTy, args),
   1240                setOptimizedPropertyFn, ReturnValueSlot(), args);
   1241     } else {
   1242       args.add(RValue::get(ivarOffset), getContext().getPointerDiffType());
   1243       args.add(RValue::get(arg), getContext().getObjCIdType());
   1244       args.add(RValue::get(Builder.getInt1(strategy.isAtomic())),
   1245                getContext().BoolTy);
   1246       args.add(RValue::get(Builder.getInt1(strategy.isCopy())),
   1247                getContext().BoolTy);
   1248       // FIXME: We shouldn't need to get the function info here, the runtime
   1249       // already should have computed it to build the function.
   1250       EmitCall(getTypes().arrangeBuiltinFunctionCall(getContext().VoidTy, args),
   1251                setPropertyFn, ReturnValueSlot(), args);
   1252     }
   1253 
   1254     return;
   1255   }
   1256 
   1257   case PropertyImplStrategy::CopyStruct:
   1258     emitStructSetterCall(*this, setterMethod, ivar);
   1259     return;
   1260 
   1261   case PropertyImplStrategy::Expression:
   1262     break;
   1263   }
   1264 
   1265   // Otherwise, fake up some ASTs and emit a normal assignment.
   1266   ValueDecl *selfDecl = setterMethod->getSelfDecl();
   1267   DeclRefExpr self(selfDecl, false, selfDecl->getType(),
   1268                    VK_LValue, SourceLocation());
   1269   ImplicitCastExpr selfLoad(ImplicitCastExpr::OnStack,
   1270                             selfDecl->getType(), CK_LValueToRValue, &self,
   1271                             VK_RValue);
   1272   ObjCIvarRefExpr ivarRef(ivar, ivar->getType().getNonReferenceType(),
   1273                           SourceLocation(), SourceLocation(),
   1274                           &selfLoad, true, true);
   1275 
   1276   ParmVarDecl *argDecl = *setterMethod->param_begin();
   1277   QualType argType = argDecl->getType().getNonReferenceType();
   1278   DeclRefExpr arg(argDecl, false, argType, VK_LValue, SourceLocation());
   1279   ImplicitCastExpr argLoad(ImplicitCastExpr::OnStack,
   1280                            argType.getUnqualifiedType(), CK_LValueToRValue,
   1281                            &arg, VK_RValue);
   1282 
   1283   // The property type can differ from the ivar type in some situations with
   1284   // Objective-C pointer types, we can always bit cast the RHS in these cases.
   1285   // The following absurdity is just to ensure well-formed IR.
   1286   CastKind argCK = CK_NoOp;
   1287   if (ivarRef.getType()->isObjCObjectPointerType()) {
   1288     if (argLoad.getType()->isObjCObjectPointerType())
   1289       argCK = CK_BitCast;
   1290     else if (argLoad.getType()->isBlockPointerType())
   1291       argCK = CK_BlockPointerToObjCPointerCast;
   1292     else
   1293       argCK = CK_CPointerToObjCPointerCast;
   1294   } else if (ivarRef.getType()->isBlockPointerType()) {
   1295      if (argLoad.getType()->isBlockPointerType())
   1296       argCK = CK_BitCast;
   1297     else
   1298       argCK = CK_AnyPointerToBlockPointerCast;
   1299   } else if (ivarRef.getType()->isPointerType()) {
   1300     argCK = CK_BitCast;
   1301   }
   1302   ImplicitCastExpr argCast(ImplicitCastExpr::OnStack,
   1303                            ivarRef.getType(), argCK, &argLoad,
   1304                            VK_RValue);
   1305   Expr *finalArg = &argLoad;
   1306   if (!getContext().hasSameUnqualifiedType(ivarRef.getType(),
   1307                                            argLoad.getType()))
   1308     finalArg = &argCast;
   1309 
   1310 
   1311   BinaryOperator assign(&ivarRef, finalArg, BO_Assign,
   1312                         ivarRef.getType(), VK_RValue, OK_Ordinary,
   1313                         SourceLocation(), false);
   1314   EmitStmt(&assign);
   1315 }
   1316 
   1317 /// \brief Generate an Objective-C property setter function.
   1318 ///
   1319 /// The given Decl must be an ObjCImplementationDecl. \@synthesize
   1320 /// is illegal within a category.
   1321 void CodeGenFunction::GenerateObjCSetter(ObjCImplementationDecl *IMP,
   1322                                          const ObjCPropertyImplDecl *PID) {
   1323   llvm::Constant *AtomicHelperFn =
   1324       CodeGenFunction(CGM).GenerateObjCAtomicSetterCopyHelperFunction(PID);
   1325   const ObjCPropertyDecl *PD = PID->getPropertyDecl();
   1326   ObjCMethodDecl *OMD = PD->getSetterMethodDecl();
   1327   assert(OMD && "Invalid call to generate setter (empty method)");
   1328   StartObjCMethod(OMD, IMP->getClassInterface());
   1329 
   1330   generateObjCSetterBody(IMP, PID, AtomicHelperFn);
   1331 
   1332   FinishFunction();
   1333 }
   1334 
   1335 namespace {
   1336   struct DestroyIvar final : EHScopeStack::Cleanup {
   1337   private:
   1338     llvm::Value *addr;
   1339     const ObjCIvarDecl *ivar;
   1340     CodeGenFunction::Destroyer *destroyer;
   1341     bool useEHCleanupForArray;
   1342   public:
   1343     DestroyIvar(llvm::Value *addr, const ObjCIvarDecl *ivar,
   1344                 CodeGenFunction::Destroyer *destroyer,
   1345                 bool useEHCleanupForArray)
   1346       : addr(addr), ivar(ivar), destroyer(destroyer),
   1347         useEHCleanupForArray(useEHCleanupForArray) {}
   1348 
   1349     void Emit(CodeGenFunction &CGF, Flags flags) override {
   1350       LValue lvalue
   1351         = CGF.EmitLValueForIvar(CGF.TypeOfSelfObject(), addr, ivar, /*CVR*/ 0);
   1352       CGF.emitDestroy(lvalue.getAddress(), ivar->getType(), destroyer,
   1353                       flags.isForNormalCleanup() && useEHCleanupForArray);
   1354     }
   1355   };
   1356 }
   1357 
   1358 /// Like CodeGenFunction::destroyARCStrong, but do it with a call.
   1359 static void destroyARCStrongWithStore(CodeGenFunction &CGF,
   1360                                       Address addr,
   1361                                       QualType type) {
   1362   llvm::Value *null = getNullForVariable(addr);
   1363   CGF.EmitARCStoreStrongCall(addr, null, /*ignored*/ true);
   1364 }
   1365 
   1366 static void emitCXXDestructMethod(CodeGenFunction &CGF,
   1367                                   ObjCImplementationDecl *impl) {
   1368   CodeGenFunction::RunCleanupsScope scope(CGF);
   1369 
   1370   llvm::Value *self = CGF.LoadObjCSelf();
   1371 
   1372   const ObjCInterfaceDecl *iface = impl->getClassInterface();
   1373   for (const ObjCIvarDecl *ivar = iface->all_declared_ivar_begin();
   1374        ivar; ivar = ivar->getNextIvar()) {
   1375     QualType type = ivar->getType();
   1376 
   1377     // Check whether the ivar is a destructible type.
   1378     QualType::DestructionKind dtorKind = type.isDestructedType();
   1379     if (!dtorKind) continue;
   1380 
   1381     CodeGenFunction::Destroyer *destroyer = nullptr;
   1382 
   1383     // Use a call to objc_storeStrong to destroy strong ivars, for the
   1384     // general benefit of the tools.
   1385     if (dtorKind == QualType::DK_objc_strong_lifetime) {
   1386       destroyer = destroyARCStrongWithStore;
   1387 
   1388     // Otherwise use the default for the destruction kind.
   1389     } else {
   1390       destroyer = CGF.getDestroyer(dtorKind);
   1391     }
   1392 
   1393     CleanupKind cleanupKind = CGF.getCleanupKind(dtorKind);
   1394 
   1395     CGF.EHStack.pushCleanup<DestroyIvar>(cleanupKind, self, ivar, destroyer,
   1396                                          cleanupKind & EHCleanup);
   1397   }
   1398 
   1399   assert(scope.requiresCleanups() && "nothing to do in .cxx_destruct?");
   1400 }
   1401 
   1402 void CodeGenFunction::GenerateObjCCtorDtorMethod(ObjCImplementationDecl *IMP,
   1403                                                  ObjCMethodDecl *MD,
   1404                                                  bool ctor) {
   1405   MD->createImplicitParams(CGM.getContext(), IMP->getClassInterface());
   1406   StartObjCMethod(MD, IMP->getClassInterface());
   1407 
   1408   // Emit .cxx_construct.
   1409   if (ctor) {
   1410     // Suppress the final autorelease in ARC.
   1411     AutoreleaseResult = false;
   1412 
   1413     for (const auto *IvarInit : IMP->inits()) {
   1414       FieldDecl *Field = IvarInit->getAnyMember();
   1415       ObjCIvarDecl *Ivar = cast<ObjCIvarDecl>(Field);
   1416       LValue LV = EmitLValueForIvar(TypeOfSelfObject(),
   1417                                     LoadObjCSelf(), Ivar, 0);
   1418       EmitAggExpr(IvarInit->getInit(),
   1419                   AggValueSlot::forLValue(LV, AggValueSlot::IsDestructed,
   1420                                           AggValueSlot::DoesNotNeedGCBarriers,
   1421                                           AggValueSlot::IsNotAliased));
   1422     }
   1423     // constructor returns 'self'.
   1424     CodeGenTypes &Types = CGM.getTypes();
   1425     QualType IdTy(CGM.getContext().getObjCIdType());
   1426     llvm::Value *SelfAsId =
   1427       Builder.CreateBitCast(LoadObjCSelf(), Types.ConvertType(IdTy));
   1428     EmitReturnOfRValue(RValue::get(SelfAsId), IdTy);
   1429 
   1430   // Emit .cxx_destruct.
   1431   } else {
   1432     emitCXXDestructMethod(*this, IMP);
   1433   }
   1434   FinishFunction();
   1435 }
   1436 
   1437 llvm::Value *CodeGenFunction::LoadObjCSelf() {
   1438   VarDecl *Self = cast<ObjCMethodDecl>(CurFuncDecl)->getSelfDecl();
   1439   DeclRefExpr DRE(Self, /*is enclosing local*/ (CurFuncDecl != CurCodeDecl),
   1440                   Self->getType(), VK_LValue, SourceLocation());
   1441   return EmitLoadOfScalar(EmitDeclRefLValue(&DRE), SourceLocation());
   1442 }
   1443 
   1444 QualType CodeGenFunction::TypeOfSelfObject() {
   1445   const ObjCMethodDecl *OMD = cast<ObjCMethodDecl>(CurFuncDecl);
   1446   ImplicitParamDecl *selfDecl = OMD->getSelfDecl();
   1447   const ObjCObjectPointerType *PTy = cast<ObjCObjectPointerType>(
   1448     getContext().getCanonicalType(selfDecl->getType()));
   1449   return PTy->getPointeeType();
   1450 }
   1451 
   1452 void CodeGenFunction::EmitObjCForCollectionStmt(const ObjCForCollectionStmt &S){
   1453   llvm::Constant *EnumerationMutationFn =
   1454     CGM.getObjCRuntime().EnumerationMutationFunction();
   1455 
   1456   if (!EnumerationMutationFn) {
   1457     CGM.ErrorUnsupported(&S, "Obj-C fast enumeration for this runtime");
   1458     return;
   1459   }
   1460 
   1461   CGDebugInfo *DI = getDebugInfo();
   1462   if (DI)
   1463     DI->EmitLexicalBlockStart(Builder, S.getSourceRange().getBegin());
   1464 
   1465   // The local variable comes into scope immediately.
   1466   AutoVarEmission variable = AutoVarEmission::invalid();
   1467   if (const DeclStmt *SD = dyn_cast<DeclStmt>(S.getElement()))
   1468     variable = EmitAutoVarAlloca(*cast<VarDecl>(SD->getSingleDecl()));
   1469 
   1470   JumpDest LoopEnd = getJumpDestInCurrentScope("forcoll.end");
   1471 
   1472   // Fast enumeration state.
   1473   QualType StateTy = CGM.getObjCFastEnumerationStateType();
   1474   Address StatePtr = CreateMemTemp(StateTy, "state.ptr");
   1475   EmitNullInitialization(StatePtr, StateTy);
   1476 
   1477   // Number of elements in the items array.
   1478   static const unsigned NumItems = 16;
   1479 
   1480   // Fetch the countByEnumeratingWithState:objects:count: selector.
   1481   IdentifierInfo *II[] = {
   1482     &CGM.getContext().Idents.get("countByEnumeratingWithState"),
   1483     &CGM.getContext().Idents.get("objects"),
   1484     &CGM.getContext().Idents.get("count")
   1485   };
   1486   Selector FastEnumSel =
   1487     CGM.getContext().Selectors.getSelector(llvm::array_lengthof(II), &II[0]);
   1488 
   1489   QualType ItemsTy =
   1490     getContext().getConstantArrayType(getContext().getObjCIdType(),
   1491                                       llvm::APInt(32, NumItems),
   1492                                       ArrayType::Normal, 0);
   1493   Address ItemsPtr = CreateMemTemp(ItemsTy, "items.ptr");
   1494 
   1495   RunCleanupsScope ForScope(*this);
   1496 
   1497   // Emit the collection pointer.  In ARC, we do a retain.
   1498   llvm::Value *Collection;
   1499   if (getLangOpts().ObjCAutoRefCount) {
   1500     Collection = EmitARCRetainScalarExpr(S.getCollection());
   1501 
   1502     // Enter a cleanup to do the release.
   1503     EmitObjCConsumeObject(S.getCollection()->getType(), Collection);
   1504   } else {
   1505     Collection = EmitScalarExpr(S.getCollection());
   1506   }
   1507 
   1508   // The 'continue' label needs to appear within the cleanup for the
   1509   // collection object.
   1510   JumpDest AfterBody = getJumpDestInCurrentScope("forcoll.next");
   1511 
   1512   // Send it our message:
   1513   CallArgList Args;
   1514 
   1515   // The first argument is a temporary of the enumeration-state type.
   1516   Args.add(RValue::get(StatePtr.getPointer()),
   1517            getContext().getPointerType(StateTy));
   1518 
   1519   // The second argument is a temporary array with space for NumItems
   1520   // pointers.  We'll actually be loading elements from the array
   1521   // pointer written into the control state; this buffer is so that
   1522   // collections that *aren't* backed by arrays can still queue up
   1523   // batches of elements.
   1524   Args.add(RValue::get(ItemsPtr.getPointer()),
   1525            getContext().getPointerType(ItemsTy));
   1526 
   1527   // The third argument is the capacity of that temporary array.
   1528   llvm::Type *UnsignedLongLTy = ConvertType(getContext().UnsignedLongTy);
   1529   llvm::Constant *Count = llvm::ConstantInt::get(UnsignedLongLTy, NumItems);
   1530   Args.add(RValue::get(Count), getContext().UnsignedLongTy);
   1531 
   1532   // Start the enumeration.
   1533   RValue CountRV =
   1534     CGM.getObjCRuntime().GenerateMessageSend(*this, ReturnValueSlot(),
   1535                                              getContext().UnsignedLongTy,
   1536                                              FastEnumSel,
   1537                                              Collection, Args);
   1538 
   1539   // The initial number of objects that were returned in the buffer.
   1540   llvm::Value *initialBufferLimit = CountRV.getScalarVal();
   1541 
   1542   llvm::BasicBlock *EmptyBB = createBasicBlock("forcoll.empty");
   1543   llvm::BasicBlock *LoopInitBB = createBasicBlock("forcoll.loopinit");
   1544 
   1545   llvm::Value *zero = llvm::Constant::getNullValue(UnsignedLongLTy);
   1546 
   1547   // If the limit pointer was zero to begin with, the collection is
   1548   // empty; skip all this. Set the branch weight assuming this has the same
   1549   // probability of exiting the loop as any other loop exit.
   1550   uint64_t EntryCount = getCurrentProfileCount();
   1551   Builder.CreateCondBr(
   1552       Builder.CreateICmpEQ(initialBufferLimit, zero, "iszero"), EmptyBB,
   1553       LoopInitBB,
   1554       createProfileWeights(EntryCount, getProfileCount(S.getBody())));
   1555 
   1556   // Otherwise, initialize the loop.
   1557   EmitBlock(LoopInitBB);
   1558 
   1559   // Save the initial mutations value.  This is the value at an
   1560   // address that was written into the state object by
   1561   // countByEnumeratingWithState:objects:count:.
   1562   Address StateMutationsPtrPtr = Builder.CreateStructGEP(
   1563       StatePtr, 2, 2 * getPointerSize(), "mutationsptr.ptr");
   1564   llvm::Value *StateMutationsPtr
   1565     = Builder.CreateLoad(StateMutationsPtrPtr, "mutationsptr");
   1566 
   1567   llvm::Value *initialMutations =
   1568     Builder.CreateAlignedLoad(StateMutationsPtr, getPointerAlign(),
   1569                               "forcoll.initial-mutations");
   1570 
   1571   // Start looping.  This is the point we return to whenever we have a
   1572   // fresh, non-empty batch of objects.
   1573   llvm::BasicBlock *LoopBodyBB = createBasicBlock("forcoll.loopbody");
   1574   EmitBlock(LoopBodyBB);
   1575 
   1576   // The current index into the buffer.
   1577   llvm::PHINode *index = Builder.CreatePHI(UnsignedLongLTy, 3, "forcoll.index");
   1578   index->addIncoming(zero, LoopInitBB);
   1579 
   1580   // The current buffer size.
   1581   llvm::PHINode *count = Builder.CreatePHI(UnsignedLongLTy, 3, "forcoll.count");
   1582   count->addIncoming(initialBufferLimit, LoopInitBB);
   1583 
   1584   incrementProfileCounter(&S);
   1585 
   1586   // Check whether the mutations value has changed from where it was
   1587   // at start.  StateMutationsPtr should actually be invariant between
   1588   // refreshes.
   1589   StateMutationsPtr = Builder.CreateLoad(StateMutationsPtrPtr, "mutationsptr");
   1590   llvm::Value *currentMutations
   1591     = Builder.CreateAlignedLoad(StateMutationsPtr, getPointerAlign(),
   1592                                 "statemutations");
   1593 
   1594   llvm::BasicBlock *WasMutatedBB = createBasicBlock("forcoll.mutated");
   1595   llvm::BasicBlock *WasNotMutatedBB = createBasicBlock("forcoll.notmutated");
   1596 
   1597   Builder.CreateCondBr(Builder.CreateICmpEQ(currentMutations, initialMutations),
   1598                        WasNotMutatedBB, WasMutatedBB);
   1599 
   1600   // If so, call the enumeration-mutation function.
   1601   EmitBlock(WasMutatedBB);
   1602   llvm::Value *V =
   1603     Builder.CreateBitCast(Collection,
   1604                           ConvertType(getContext().getObjCIdType()));
   1605   CallArgList Args2;
   1606   Args2.add(RValue::get(V), getContext().getObjCIdType());
   1607   // FIXME: We shouldn't need to get the function info here, the runtime already
   1608   // should have computed it to build the function.
   1609   EmitCall(
   1610           CGM.getTypes().arrangeBuiltinFunctionCall(getContext().VoidTy, Args2),
   1611            EnumerationMutationFn, ReturnValueSlot(), Args2);
   1612 
   1613   // Otherwise, or if the mutation function returns, just continue.
   1614   EmitBlock(WasNotMutatedBB);
   1615 
   1616   // Initialize the element variable.
   1617   RunCleanupsScope elementVariableScope(*this);
   1618   bool elementIsVariable;
   1619   LValue elementLValue;
   1620   QualType elementType;
   1621   if (const DeclStmt *SD = dyn_cast<DeclStmt>(S.getElement())) {
   1622     // Initialize the variable, in case it's a __block variable or something.
   1623     EmitAutoVarInit(variable);
   1624 
   1625     const VarDecl* D = cast<VarDecl>(SD->getSingleDecl());
   1626     DeclRefExpr tempDRE(const_cast<VarDecl*>(D), false, D->getType(),
   1627                         VK_LValue, SourceLocation());
   1628     elementLValue = EmitLValue(&tempDRE);
   1629     elementType = D->getType();
   1630     elementIsVariable = true;
   1631 
   1632     if (D->isARCPseudoStrong())
   1633       elementLValue.getQuals().setObjCLifetime(Qualifiers::OCL_ExplicitNone);
   1634   } else {
   1635     elementLValue = LValue(); // suppress warning
   1636     elementType = cast<Expr>(S.getElement())->getType();
   1637     elementIsVariable = false;
   1638   }
   1639   llvm::Type *convertedElementType = ConvertType(elementType);
   1640 
   1641   // Fetch the buffer out of the enumeration state.
   1642   // TODO: this pointer should actually be invariant between
   1643   // refreshes, which would help us do certain loop optimizations.
   1644   Address StateItemsPtr = Builder.CreateStructGEP(
   1645       StatePtr, 1, getPointerSize(), "stateitems.ptr");
   1646   llvm::Value *EnumStateItems =
   1647     Builder.CreateLoad(StateItemsPtr, "stateitems");
   1648 
   1649   // Fetch the value at the current index from the buffer.
   1650   llvm::Value *CurrentItemPtr =
   1651     Builder.CreateGEP(EnumStateItems, index, "currentitem.ptr");
   1652   llvm::Value *CurrentItem =
   1653     Builder.CreateAlignedLoad(CurrentItemPtr, getPointerAlign());
   1654 
   1655   // Cast that value to the right type.
   1656   CurrentItem = Builder.CreateBitCast(CurrentItem, convertedElementType,
   1657                                       "currentitem");
   1658 
   1659   // Make sure we have an l-value.  Yes, this gets evaluated every
   1660   // time through the loop.
   1661   if (!elementIsVariable) {
   1662     elementLValue = EmitLValue(cast<Expr>(S.getElement()));
   1663     EmitStoreThroughLValue(RValue::get(CurrentItem), elementLValue);
   1664   } else {
   1665     EmitScalarInit(CurrentItem, elementLValue);
   1666   }
   1667 
   1668   // If we do have an element variable, this assignment is the end of
   1669   // its initialization.
   1670   if (elementIsVariable)
   1671     EmitAutoVarCleanups(variable);
   1672 
   1673   // Perform the loop body, setting up break and continue labels.
   1674   BreakContinueStack.push_back(BreakContinue(LoopEnd, AfterBody));
   1675   {
   1676     RunCleanupsScope Scope(*this);
   1677     EmitStmt(S.getBody());
   1678   }
   1679   BreakContinueStack.pop_back();
   1680 
   1681   // Destroy the element variable now.
   1682   elementVariableScope.ForceCleanup();
   1683 
   1684   // Check whether there are more elements.
   1685   EmitBlock(AfterBody.getBlock());
   1686 
   1687   llvm::BasicBlock *FetchMoreBB = createBasicBlock("forcoll.refetch");
   1688 
   1689   // First we check in the local buffer.
   1690   llvm::Value *indexPlusOne
   1691     = Builder.CreateAdd(index, llvm::ConstantInt::get(UnsignedLongLTy, 1));
   1692 
   1693   // If we haven't overrun the buffer yet, we can continue.
   1694   // Set the branch weights based on the simplifying assumption that this is
   1695   // like a while-loop, i.e., ignoring that the false branch fetches more
   1696   // elements and then returns to the loop.
   1697   Builder.CreateCondBr(
   1698       Builder.CreateICmpULT(indexPlusOne, count), LoopBodyBB, FetchMoreBB,
   1699       createProfileWeights(getProfileCount(S.getBody()), EntryCount));
   1700 
   1701   index->addIncoming(indexPlusOne, AfterBody.getBlock());
   1702   count->addIncoming(count, AfterBody.getBlock());
   1703 
   1704   // Otherwise, we have to fetch more elements.
   1705   EmitBlock(FetchMoreBB);
   1706 
   1707   CountRV =
   1708     CGM.getObjCRuntime().GenerateMessageSend(*this, ReturnValueSlot(),
   1709                                              getContext().UnsignedLongTy,
   1710                                              FastEnumSel,
   1711                                              Collection, Args);
   1712 
   1713   // If we got a zero count, we're done.
   1714   llvm::Value *refetchCount = CountRV.getScalarVal();
   1715 
   1716   // (note that the message send might split FetchMoreBB)
   1717   index->addIncoming(zero, Builder.GetInsertBlock());
   1718   count->addIncoming(refetchCount, Builder.GetInsertBlock());
   1719 
   1720   Builder.CreateCondBr(Builder.CreateICmpEQ(refetchCount, zero),
   1721                        EmptyBB, LoopBodyBB);
   1722 
   1723   // No more elements.
   1724   EmitBlock(EmptyBB);
   1725 
   1726   if (!elementIsVariable) {
   1727     // If the element was not a declaration, set it to be null.
   1728 
   1729     llvm::Value *null = llvm::Constant::getNullValue(convertedElementType);
   1730     elementLValue = EmitLValue(cast<Expr>(S.getElement()));
   1731     EmitStoreThroughLValue(RValue::get(null), elementLValue);
   1732   }
   1733 
   1734   if (DI)
   1735     DI->EmitLexicalBlockEnd(Builder, S.getSourceRange().getEnd());
   1736 
   1737   ForScope.ForceCleanup();
   1738   EmitBlock(LoopEnd.getBlock());
   1739 }
   1740 
   1741 void CodeGenFunction::EmitObjCAtTryStmt(const ObjCAtTryStmt &S) {
   1742   CGM.getObjCRuntime().EmitTryStmt(*this, S);
   1743 }
   1744 
   1745 void CodeGenFunction::EmitObjCAtThrowStmt(const ObjCAtThrowStmt &S) {
   1746   CGM.getObjCRuntime().EmitThrowStmt(*this, S);
   1747 }
   1748 
   1749 void CodeGenFunction::EmitObjCAtSynchronizedStmt(
   1750                                               const ObjCAtSynchronizedStmt &S) {
   1751   CGM.getObjCRuntime().EmitSynchronizedStmt(*this, S);
   1752 }
   1753 
   1754 namespace {
   1755   struct CallObjCRelease final : EHScopeStack::Cleanup {
   1756     CallObjCRelease(llvm::Value *object) : object(object) {}
   1757     llvm::Value *object;
   1758 
   1759     void Emit(CodeGenFunction &CGF, Flags flags) override {
   1760       // Releases at the end of the full-expression are imprecise.
   1761       CGF.EmitARCRelease(object, ARCImpreciseLifetime);
   1762     }
   1763   };
   1764 }
   1765 
   1766 /// Produce the code for a CK_ARCConsumeObject.  Does a primitive
   1767 /// release at the end of the full-expression.
   1768 llvm::Value *CodeGenFunction::EmitObjCConsumeObject(QualType type,
   1769                                                     llvm::Value *object) {
   1770   // If we're in a conditional branch, we need to make the cleanup
   1771   // conditional.
   1772   pushFullExprCleanup<CallObjCRelease>(getARCCleanupKind(), object);
   1773   return object;
   1774 }
   1775 
   1776 llvm::Value *CodeGenFunction::EmitObjCExtendObjectLifetime(QualType type,
   1777                                                            llvm::Value *value) {
   1778   return EmitARCRetainAutorelease(type, value);
   1779 }
   1780 
   1781 /// Given a number of pointers, inform the optimizer that they're
   1782 /// being intrinsically used up until this point in the program.
   1783 void CodeGenFunction::EmitARCIntrinsicUse(ArrayRef<llvm::Value*> values) {
   1784   llvm::Constant *&fn = CGM.getObjCEntrypoints().clang_arc_use;
   1785   if (!fn) {
   1786     llvm::FunctionType *fnType =
   1787       llvm::FunctionType::get(CGM.VoidTy, None, true);
   1788     fn = CGM.CreateRuntimeFunction(fnType, "clang.arc.use");
   1789   }
   1790 
   1791   // This isn't really a "runtime" function, but as an intrinsic it
   1792   // doesn't really matter as long as we align things up.
   1793   EmitNounwindRuntimeCall(fn, values);
   1794 }
   1795 
   1796 
   1797 static llvm::Constant *createARCRuntimeFunction(CodeGenModule &CGM,
   1798                                                 llvm::FunctionType *type,
   1799                                                 StringRef fnName) {
   1800   llvm::Constant *fn = CGM.CreateRuntimeFunction(type, fnName);
   1801 
   1802   if (llvm::Function *f = dyn_cast<llvm::Function>(fn)) {
   1803     // If the target runtime doesn't naturally support ARC, emit weak
   1804     // references to the runtime support library.  We don't really
   1805     // permit this to fail, but we need a particular relocation style.
   1806     if (!CGM.getLangOpts().ObjCRuntime.hasNativeARC()) {
   1807       f->setLinkage(llvm::Function::ExternalWeakLinkage);
   1808     } else if (fnName == "objc_retain" || fnName  == "objc_release") {
   1809       // If we have Native ARC, set nonlazybind attribute for these APIs for
   1810       // performance.
   1811       f->addFnAttr(llvm::Attribute::NonLazyBind);
   1812     }
   1813   }
   1814 
   1815   return fn;
   1816 }
   1817 
   1818 /// Perform an operation having the signature
   1819 ///   i8* (i8*)
   1820 /// where a null input causes a no-op and returns null.
   1821 static llvm::Value *emitARCValueOperation(CodeGenFunction &CGF,
   1822                                           llvm::Value *value,
   1823                                           llvm::Constant *&fn,
   1824                                           StringRef fnName,
   1825                                           bool isTailCall = false) {
   1826   if (isa<llvm::ConstantPointerNull>(value)) return value;
   1827 
   1828   if (!fn) {
   1829     llvm::FunctionType *fnType =
   1830       llvm::FunctionType::get(CGF.Int8PtrTy, CGF.Int8PtrTy, false);
   1831     fn = createARCRuntimeFunction(CGF.CGM, fnType, fnName);
   1832   }
   1833 
   1834   // Cast the argument to 'id'.
   1835   llvm::Type *origType = value->getType();
   1836   value = CGF.Builder.CreateBitCast(value, CGF.Int8PtrTy);
   1837 
   1838   // Call the function.
   1839   llvm::CallInst *call = CGF.EmitNounwindRuntimeCall(fn, value);
   1840   if (isTailCall)
   1841     call->setTailCall();
   1842 
   1843   // Cast the result back to the original type.
   1844   return CGF.Builder.CreateBitCast(call, origType);
   1845 }
   1846 
   1847 /// Perform an operation having the following signature:
   1848 ///   i8* (i8**)
   1849 static llvm::Value *emitARCLoadOperation(CodeGenFunction &CGF,
   1850                                          Address addr,
   1851                                          llvm::Constant *&fn,
   1852                                          StringRef fnName) {
   1853   if (!fn) {
   1854     llvm::FunctionType *fnType =
   1855       llvm::FunctionType::get(CGF.Int8PtrTy, CGF.Int8PtrPtrTy, false);
   1856     fn = createARCRuntimeFunction(CGF.CGM, fnType, fnName);
   1857   }
   1858 
   1859   // Cast the argument to 'id*'.
   1860   llvm::Type *origType = addr.getElementType();
   1861   addr = CGF.Builder.CreateBitCast(addr, CGF.Int8PtrPtrTy);
   1862 
   1863   // Call the function.
   1864   llvm::Value *result = CGF.EmitNounwindRuntimeCall(fn, addr.getPointer());
   1865 
   1866   // Cast the result back to a dereference of the original type.
   1867   if (origType != CGF.Int8PtrTy)
   1868     result = CGF.Builder.CreateBitCast(result, origType);
   1869 
   1870   return result;
   1871 }
   1872 
   1873 /// Perform an operation having the following signature:
   1874 ///   i8* (i8**, i8*)
   1875 static llvm::Value *emitARCStoreOperation(CodeGenFunction &CGF,
   1876                                           Address addr,
   1877                                           llvm::Value *value,
   1878                                           llvm::Constant *&fn,
   1879                                           StringRef fnName,
   1880                                           bool ignored) {
   1881   assert(addr.getElementType() == value->getType());
   1882 
   1883   if (!fn) {
   1884     llvm::Type *argTypes[] = { CGF.Int8PtrPtrTy, CGF.Int8PtrTy };
   1885 
   1886     llvm::FunctionType *fnType
   1887       = llvm::FunctionType::get(CGF.Int8PtrTy, argTypes, false);
   1888     fn = createARCRuntimeFunction(CGF.CGM, fnType, fnName);
   1889   }
   1890 
   1891   llvm::Type *origType = value->getType();
   1892 
   1893   llvm::Value *args[] = {
   1894     CGF.Builder.CreateBitCast(addr.getPointer(), CGF.Int8PtrPtrTy),
   1895     CGF.Builder.CreateBitCast(value, CGF.Int8PtrTy)
   1896   };
   1897   llvm::CallInst *result = CGF.EmitNounwindRuntimeCall(fn, args);
   1898 
   1899   if (ignored) return nullptr;
   1900 
   1901   return CGF.Builder.CreateBitCast(result, origType);
   1902 }
   1903 
   1904 /// Perform an operation having the following signature:
   1905 ///   void (i8**, i8**)
   1906 static void emitARCCopyOperation(CodeGenFunction &CGF,
   1907                                  Address dst,
   1908                                  Address src,
   1909                                  llvm::Constant *&fn,
   1910                                  StringRef fnName) {
   1911   assert(dst.getType() == src.getType());
   1912 
   1913   if (!fn) {
   1914     llvm::Type *argTypes[] = { CGF.Int8PtrPtrTy, CGF.Int8PtrPtrTy };
   1915 
   1916     llvm::FunctionType *fnType
   1917       = llvm::FunctionType::get(CGF.Builder.getVoidTy(), argTypes, false);
   1918     fn = createARCRuntimeFunction(CGF.CGM, fnType, fnName);
   1919   }
   1920 
   1921   llvm::Value *args[] = {
   1922     CGF.Builder.CreateBitCast(dst.getPointer(), CGF.Int8PtrPtrTy),
   1923     CGF.Builder.CreateBitCast(src.getPointer(), CGF.Int8PtrPtrTy)
   1924   };
   1925   CGF.EmitNounwindRuntimeCall(fn, args);
   1926 }
   1927 
   1928 /// Produce the code to do a retain.  Based on the type, calls one of:
   1929 ///   call i8* \@objc_retain(i8* %value)
   1930 ///   call i8* \@objc_retainBlock(i8* %value)
   1931 llvm::Value *CodeGenFunction::EmitARCRetain(QualType type, llvm::Value *value) {
   1932   if (type->isBlockPointerType())
   1933     return EmitARCRetainBlock(value, /*mandatory*/ false);
   1934   else
   1935     return EmitARCRetainNonBlock(value);
   1936 }
   1937 
   1938 /// Retain the given object, with normal retain semantics.
   1939 ///   call i8* \@objc_retain(i8* %value)
   1940 llvm::Value *CodeGenFunction::EmitARCRetainNonBlock(llvm::Value *value) {
   1941   return emitARCValueOperation(*this, value,
   1942                                CGM.getObjCEntrypoints().objc_retain,
   1943                                "objc_retain");
   1944 }
   1945 
   1946 /// Retain the given block, with _Block_copy semantics.
   1947 ///   call i8* \@objc_retainBlock(i8* %value)
   1948 ///
   1949 /// \param mandatory - If false, emit the call with metadata
   1950 /// indicating that it's okay for the optimizer to eliminate this call
   1951 /// if it can prove that the block never escapes except down the stack.
   1952 llvm::Value *CodeGenFunction::EmitARCRetainBlock(llvm::Value *value,
   1953                                                  bool mandatory) {
   1954   llvm::Value *result
   1955     = emitARCValueOperation(*this, value,
   1956                             CGM.getObjCEntrypoints().objc_retainBlock,
   1957                             "objc_retainBlock");
   1958 
   1959   // If the copy isn't mandatory, add !clang.arc.copy_on_escape to
   1960   // tell the optimizer that it doesn't need to do this copy if the
   1961   // block doesn't escape, where being passed as an argument doesn't
   1962   // count as escaping.
   1963   if (!mandatory && isa<llvm::Instruction>(result)) {
   1964     llvm::CallInst *call
   1965       = cast<llvm::CallInst>(result->stripPointerCasts());
   1966     assert(call->getCalledValue() == CGM.getObjCEntrypoints().objc_retainBlock);
   1967 
   1968     call->setMetadata("clang.arc.copy_on_escape",
   1969                       llvm::MDNode::get(Builder.getContext(), None));
   1970   }
   1971 
   1972   return result;
   1973 }
   1974 
   1975 static void emitAutoreleasedReturnValueMarker(CodeGenFunction &CGF) {
   1976   // Fetch the void(void) inline asm which marks that we're going to
   1977   // do something with the autoreleased return value.
   1978   llvm::InlineAsm *&marker
   1979     = CGF.CGM.getObjCEntrypoints().retainAutoreleasedReturnValueMarker;
   1980   if (!marker) {
   1981     StringRef assembly
   1982       = CGF.CGM.getTargetCodeGenInfo()
   1983            .getARCRetainAutoreleasedReturnValueMarker();
   1984 
   1985     // If we have an empty assembly string, there's nothing to do.
   1986     if (assembly.empty()) {
   1987 
   1988     // Otherwise, at -O0, build an inline asm that we're going to call
   1989     // in a moment.
   1990     } else if (CGF.CGM.getCodeGenOpts().OptimizationLevel == 0) {
   1991       llvm::FunctionType *type =
   1992         llvm::FunctionType::get(CGF.VoidTy, /*variadic*/false);
   1993 
   1994       marker = llvm::InlineAsm::get(type, assembly, "", /*sideeffects*/ true);
   1995 
   1996     // If we're at -O1 and above, we don't want to litter the code
   1997     // with this marker yet, so leave a breadcrumb for the ARC
   1998     // optimizer to pick up.
   1999     } else {
   2000       llvm::NamedMDNode *metadata =
   2001         CGF.CGM.getModule().getOrInsertNamedMetadata(
   2002                             "clang.arc.retainAutoreleasedReturnValueMarker");
   2003       assert(metadata->getNumOperands() <= 1);
   2004       if (metadata->getNumOperands() == 0) {
   2005         auto &ctx = CGF.getLLVMContext();
   2006         metadata->addOperand(llvm::MDNode::get(ctx,
   2007                                      llvm::MDString::get(ctx, assembly)));
   2008       }
   2009     }
   2010   }
   2011 
   2012   // Call the marker asm if we made one, which we do only at -O0.
   2013   if (marker)
   2014     CGF.Builder.CreateCall(marker);
   2015 }
   2016 
   2017 /// Retain the given object which is the result of a function call.
   2018 ///   call i8* \@objc_retainAutoreleasedReturnValue(i8* %value)
   2019 ///
   2020 /// Yes, this function name is one character away from a different
   2021 /// call with completely different semantics.
   2022 llvm::Value *
   2023 CodeGenFunction::EmitARCRetainAutoreleasedReturnValue(llvm::Value *value) {
   2024   emitAutoreleasedReturnValueMarker(*this);
   2025   return emitARCValueOperation(*this, value,
   2026               CGM.getObjCEntrypoints().objc_retainAutoreleasedReturnValue,
   2027                                "objc_retainAutoreleasedReturnValue");
   2028 }
   2029 
   2030 /// Claim a possibly-autoreleased return value at +0.  This is only
   2031 /// valid to do in contexts which do not rely on the retain to keep
   2032 /// the object valid for for all of its uses; for example, when
   2033 /// the value is ignored, or when it is being assigned to an
   2034 /// __unsafe_unretained variable.
   2035 ///
   2036 ///   call i8* \@objc_unsafeClaimAutoreleasedReturnValue(i8* %value)
   2037 llvm::Value *
   2038 CodeGenFunction::EmitARCUnsafeClaimAutoreleasedReturnValue(llvm::Value *value) {
   2039   emitAutoreleasedReturnValueMarker(*this);
   2040   return emitARCValueOperation(*this, value,
   2041               CGM.getObjCEntrypoints().objc_unsafeClaimAutoreleasedReturnValue,
   2042                                "objc_unsafeClaimAutoreleasedReturnValue");
   2043 }
   2044 
   2045 /// Release the given object.
   2046 ///   call void \@objc_release(i8* %value)
   2047 void CodeGenFunction::EmitARCRelease(llvm::Value *value,
   2048                                      ARCPreciseLifetime_t precise) {
   2049   if (isa<llvm::ConstantPointerNull>(value)) return;
   2050 
   2051   llvm::Constant *&fn = CGM.getObjCEntrypoints().objc_release;
   2052   if (!fn) {
   2053     llvm::FunctionType *fnType =
   2054       llvm::FunctionType::get(Builder.getVoidTy(), Int8PtrTy, false);
   2055     fn = createARCRuntimeFunction(CGM, fnType, "objc_release");
   2056   }
   2057 
   2058   // Cast the argument to 'id'.
   2059   value = Builder.CreateBitCast(value, Int8PtrTy);
   2060 
   2061   // Call objc_release.
   2062   llvm::CallInst *call = EmitNounwindRuntimeCall(fn, value);
   2063 
   2064   if (precise == ARCImpreciseLifetime) {
   2065     call->setMetadata("clang.imprecise_release",
   2066                       llvm::MDNode::get(Builder.getContext(), None));
   2067   }
   2068 }
   2069 
   2070 /// Destroy a __strong variable.
   2071 ///
   2072 /// At -O0, emit a call to store 'null' into the address;
   2073 /// instrumenting tools prefer this because the address is exposed,
   2074 /// but it's relatively cumbersome to optimize.
   2075 ///
   2076 /// At -O1 and above, just load and call objc_release.
   2077 ///
   2078 ///   call void \@objc_storeStrong(i8** %addr, i8* null)
   2079 void CodeGenFunction::EmitARCDestroyStrong(Address addr,
   2080                                            ARCPreciseLifetime_t precise) {
   2081   if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
   2082     llvm::Value *null = getNullForVariable(addr);
   2083     EmitARCStoreStrongCall(addr, null, /*ignored*/ true);
   2084     return;
   2085   }
   2086 
   2087   llvm::Value *value = Builder.CreateLoad(addr);
   2088   EmitARCRelease(value, precise);
   2089 }
   2090 
   2091 /// Store into a strong object.  Always calls this:
   2092 ///   call void \@objc_storeStrong(i8** %addr, i8* %value)
   2093 llvm::Value *CodeGenFunction::EmitARCStoreStrongCall(Address addr,
   2094                                                      llvm::Value *value,
   2095                                                      bool ignored) {
   2096   assert(addr.getElementType() == value->getType());
   2097 
   2098   llvm::Constant *&fn = CGM.getObjCEntrypoints().objc_storeStrong;
   2099   if (!fn) {
   2100     llvm::Type *argTypes[] = { Int8PtrPtrTy, Int8PtrTy };
   2101     llvm::FunctionType *fnType
   2102       = llvm::FunctionType::get(Builder.getVoidTy(), argTypes, false);
   2103     fn = createARCRuntimeFunction(CGM, fnType, "objc_storeStrong");
   2104   }
   2105 
   2106   llvm::Value *args[] = {
   2107     Builder.CreateBitCast(addr.getPointer(), Int8PtrPtrTy),
   2108     Builder.CreateBitCast(value, Int8PtrTy)
   2109   };
   2110   EmitNounwindRuntimeCall(fn, args);
   2111 
   2112   if (ignored) return nullptr;
   2113   return value;
   2114 }
   2115 
   2116 /// Store into a strong object.  Sometimes calls this:
   2117 ///   call void \@objc_storeStrong(i8** %addr, i8* %value)
   2118 /// Other times, breaks it down into components.
   2119 llvm::Value *CodeGenFunction::EmitARCStoreStrong(LValue dst,
   2120                                                  llvm::Value *newValue,
   2121                                                  bool ignored) {
   2122   QualType type = dst.getType();
   2123   bool isBlock = type->isBlockPointerType();
   2124 
   2125   // Use a store barrier at -O0 unless this is a block type or the
   2126   // lvalue is inadequately aligned.
   2127   if (shouldUseFusedARCCalls() &&
   2128       !isBlock &&
   2129       (dst.getAlignment().isZero() ||
   2130        dst.getAlignment() >= CharUnits::fromQuantity(PointerAlignInBytes))) {
   2131     return EmitARCStoreStrongCall(dst.getAddress(), newValue, ignored);
   2132   }
   2133 
   2134   // Otherwise, split it out.
   2135 
   2136   // Retain the new value.
   2137   newValue = EmitARCRetain(type, newValue);
   2138 
   2139   // Read the old value.
   2140   llvm::Value *oldValue = EmitLoadOfScalar(dst, SourceLocation());
   2141 
   2142   // Store.  We do this before the release so that any deallocs won't
   2143   // see the old value.
   2144   EmitStoreOfScalar(newValue, dst);
   2145 
   2146   // Finally, release the old value.
   2147   EmitARCRelease(oldValue, dst.isARCPreciseLifetime());
   2148 
   2149   return newValue;
   2150 }
   2151 
   2152 /// Autorelease the given object.
   2153 ///   call i8* \@objc_autorelease(i8* %value)
   2154 llvm::Value *CodeGenFunction::EmitARCAutorelease(llvm::Value *value) {
   2155   return emitARCValueOperation(*this, value,
   2156                                CGM.getObjCEntrypoints().objc_autorelease,
   2157                                "objc_autorelease");
   2158 }
   2159 
   2160 /// Autorelease the given object.
   2161 ///   call i8* \@objc_autoreleaseReturnValue(i8* %value)
   2162 llvm::Value *
   2163 CodeGenFunction::EmitARCAutoreleaseReturnValue(llvm::Value *value) {
   2164   return emitARCValueOperation(*this, value,
   2165                             CGM.getObjCEntrypoints().objc_autoreleaseReturnValue,
   2166                                "objc_autoreleaseReturnValue",
   2167                                /*isTailCall*/ true);
   2168 }
   2169 
   2170 /// Do a fused retain/autorelease of the given object.
   2171 ///   call i8* \@objc_retainAutoreleaseReturnValue(i8* %value)
   2172 llvm::Value *
   2173 CodeGenFunction::EmitARCRetainAutoreleaseReturnValue(llvm::Value *value) {
   2174   return emitARCValueOperation(*this, value,
   2175                      CGM.getObjCEntrypoints().objc_retainAutoreleaseReturnValue,
   2176                                "objc_retainAutoreleaseReturnValue",
   2177                                /*isTailCall*/ true);
   2178 }
   2179 
   2180 /// Do a fused retain/autorelease of the given object.
   2181 ///   call i8* \@objc_retainAutorelease(i8* %value)
   2182 /// or
   2183 ///   %retain = call i8* \@objc_retainBlock(i8* %value)
   2184 ///   call i8* \@objc_autorelease(i8* %retain)
   2185 llvm::Value *CodeGenFunction::EmitARCRetainAutorelease(QualType type,
   2186                                                        llvm::Value *value) {
   2187   if (!type->isBlockPointerType())
   2188     return EmitARCRetainAutoreleaseNonBlock(value);
   2189 
   2190   if (isa<llvm::ConstantPointerNull>(value)) return value;
   2191 
   2192   llvm::Type *origType = value->getType();
   2193   value = Builder.CreateBitCast(value, Int8PtrTy);
   2194   value = EmitARCRetainBlock(value, /*mandatory*/ true);
   2195   value = EmitARCAutorelease(value);
   2196   return Builder.CreateBitCast(value, origType);
   2197 }
   2198 
   2199 /// Do a fused retain/autorelease of the given object.
   2200 ///   call i8* \@objc_retainAutorelease(i8* %value)
   2201 llvm::Value *
   2202 CodeGenFunction::EmitARCRetainAutoreleaseNonBlock(llvm::Value *value) {
   2203   return emitARCValueOperation(*this, value,
   2204                                CGM.getObjCEntrypoints().objc_retainAutorelease,
   2205                                "objc_retainAutorelease");
   2206 }
   2207 
   2208 /// i8* \@objc_loadWeak(i8** %addr)
   2209 /// Essentially objc_autorelease(objc_loadWeakRetained(addr)).
   2210 llvm::Value *CodeGenFunction::EmitARCLoadWeak(Address addr) {
   2211   return emitARCLoadOperation(*this, addr,
   2212                               CGM.getObjCEntrypoints().objc_loadWeak,
   2213                               "objc_loadWeak");
   2214 }
   2215 
   2216 /// i8* \@objc_loadWeakRetained(i8** %addr)
   2217 llvm::Value *CodeGenFunction::EmitARCLoadWeakRetained(Address addr) {
   2218   return emitARCLoadOperation(*this, addr,
   2219                               CGM.getObjCEntrypoints().objc_loadWeakRetained,
   2220                               "objc_loadWeakRetained");
   2221 }
   2222 
   2223 /// i8* \@objc_storeWeak(i8** %addr, i8* %value)
   2224 /// Returns %value.
   2225 llvm::Value *CodeGenFunction::EmitARCStoreWeak(Address addr,
   2226                                                llvm::Value *value,
   2227                                                bool ignored) {
   2228   return emitARCStoreOperation(*this, addr, value,
   2229                                CGM.getObjCEntrypoints().objc_storeWeak,
   2230                                "objc_storeWeak", ignored);
   2231 }
   2232 
   2233 /// i8* \@objc_initWeak(i8** %addr, i8* %value)
   2234 /// Returns %value.  %addr is known to not have a current weak entry.
   2235 /// Essentially equivalent to:
   2236 ///   *addr = nil; objc_storeWeak(addr, value);
   2237 void CodeGenFunction::EmitARCInitWeak(Address addr, llvm::Value *value) {
   2238   // If we're initializing to null, just write null to memory; no need
   2239   // to get the runtime involved.  But don't do this if optimization
   2240   // is enabled, because accounting for this would make the optimizer
   2241   // much more complicated.
   2242   if (isa<llvm::ConstantPointerNull>(value) &&
   2243       CGM.getCodeGenOpts().OptimizationLevel == 0) {
   2244     Builder.CreateStore(value, addr);
   2245     return;
   2246   }
   2247 
   2248   emitARCStoreOperation(*this, addr, value,
   2249                         CGM.getObjCEntrypoints().objc_initWeak,
   2250                         "objc_initWeak", /*ignored*/ true);
   2251 }
   2252 
   2253 /// void \@objc_destroyWeak(i8** %addr)
   2254 /// Essentially objc_storeWeak(addr, nil).
   2255 void CodeGenFunction::EmitARCDestroyWeak(Address addr) {
   2256   llvm::Constant *&fn = CGM.getObjCEntrypoints().objc_destroyWeak;
   2257   if (!fn) {
   2258     llvm::FunctionType *fnType =
   2259       llvm::FunctionType::get(Builder.getVoidTy(), Int8PtrPtrTy, false);
   2260     fn = createARCRuntimeFunction(CGM, fnType, "objc_destroyWeak");
   2261   }
   2262 
   2263   // Cast the argument to 'id*'.
   2264   addr = Builder.CreateBitCast(addr, Int8PtrPtrTy);
   2265 
   2266   EmitNounwindRuntimeCall(fn, addr.getPointer());
   2267 }
   2268 
   2269 /// void \@objc_moveWeak(i8** %dest, i8** %src)
   2270 /// Disregards the current value in %dest.  Leaves %src pointing to nothing.
   2271 /// Essentially (objc_copyWeak(dest, src), objc_destroyWeak(src)).
   2272 void CodeGenFunction::EmitARCMoveWeak(Address dst, Address src) {
   2273   emitARCCopyOperation(*this, dst, src,
   2274                        CGM.getObjCEntrypoints().objc_moveWeak,
   2275                        "objc_moveWeak");
   2276 }
   2277 
   2278 /// void \@objc_copyWeak(i8** %dest, i8** %src)
   2279 /// Disregards the current value in %dest.  Essentially
   2280 ///   objc_release(objc_initWeak(dest, objc_readWeakRetained(src)))
   2281 void CodeGenFunction::EmitARCCopyWeak(Address dst, Address src) {
   2282   emitARCCopyOperation(*this, dst, src,
   2283                        CGM.getObjCEntrypoints().objc_copyWeak,
   2284                        "objc_copyWeak");
   2285 }
   2286 
   2287 /// Produce the code to do a objc_autoreleasepool_push.
   2288 ///   call i8* \@objc_autoreleasePoolPush(void)
   2289 llvm::Value *CodeGenFunction::EmitObjCAutoreleasePoolPush() {
   2290   llvm::Constant *&fn = CGM.getObjCEntrypoints().objc_autoreleasePoolPush;
   2291   if (!fn) {
   2292     llvm::FunctionType *fnType =
   2293       llvm::FunctionType::get(Int8PtrTy, false);
   2294     fn = createARCRuntimeFunction(CGM, fnType, "objc_autoreleasePoolPush");
   2295   }
   2296 
   2297   return EmitNounwindRuntimeCall(fn);
   2298 }
   2299 
   2300 /// Produce the code to do a primitive release.
   2301 ///   call void \@objc_autoreleasePoolPop(i8* %ptr)
   2302 void CodeGenFunction::EmitObjCAutoreleasePoolPop(llvm::Value *value) {
   2303   assert(value->getType() == Int8PtrTy);
   2304 
   2305   llvm::Constant *&fn = CGM.getObjCEntrypoints().objc_autoreleasePoolPop;
   2306   if (!fn) {
   2307     llvm::FunctionType *fnType =
   2308       llvm::FunctionType::get(Builder.getVoidTy(), Int8PtrTy, false);
   2309 
   2310     // We don't want to use a weak import here; instead we should not
   2311     // fall into this path.
   2312     fn = createARCRuntimeFunction(CGM, fnType, "objc_autoreleasePoolPop");
   2313   }
   2314 
   2315   // objc_autoreleasePoolPop can throw.
   2316   EmitRuntimeCallOrInvoke(fn, value);
   2317 }
   2318 
   2319 /// Produce the code to do an MRR version objc_autoreleasepool_push.
   2320 /// Which is: [[NSAutoreleasePool alloc] init];
   2321 /// Where alloc is declared as: + (id) alloc; in NSAutoreleasePool class.
   2322 /// init is declared as: - (id) init; in its NSObject super class.
   2323 ///
   2324 llvm::Value *CodeGenFunction::EmitObjCMRRAutoreleasePoolPush() {
   2325   CGObjCRuntime &Runtime = CGM.getObjCRuntime();
   2326   llvm::Value *Receiver = Runtime.EmitNSAutoreleasePoolClassRef(*this);
   2327   // [NSAutoreleasePool alloc]
   2328   IdentifierInfo *II = &CGM.getContext().Idents.get("alloc");
   2329   Selector AllocSel = getContext().Selectors.getSelector(0, &II);
   2330   CallArgList Args;
   2331   RValue AllocRV =
   2332     Runtime.GenerateMessageSend(*this, ReturnValueSlot(),
   2333                                 getContext().getObjCIdType(),
   2334                                 AllocSel, Receiver, Args);
   2335 
   2336   // [Receiver init]
   2337   Receiver = AllocRV.getScalarVal();
   2338   II = &CGM.getContext().Idents.get("init");
   2339   Selector InitSel = getContext().Selectors.getSelector(0, &II);
   2340   RValue InitRV =
   2341     Runtime.GenerateMessageSend(*this, ReturnValueSlot(),
   2342                                 getContext().getObjCIdType(),
   2343                                 InitSel, Receiver, Args);
   2344   return InitRV.getScalarVal();
   2345 }
   2346 
   2347 /// Produce the code to do a primitive release.
   2348 /// [tmp drain];
   2349 void CodeGenFunction::EmitObjCMRRAutoreleasePoolPop(llvm::Value *Arg) {
   2350   IdentifierInfo *II = &CGM.getContext().Idents.get("drain");
   2351   Selector DrainSel = getContext().Selectors.getSelector(0, &II);
   2352   CallArgList Args;
   2353   CGM.getObjCRuntime().GenerateMessageSend(*this, ReturnValueSlot(),
   2354                               getContext().VoidTy, DrainSel, Arg, Args);
   2355 }
   2356 
   2357 void CodeGenFunction::destroyARCStrongPrecise(CodeGenFunction &CGF,
   2358                                               Address addr,
   2359                                               QualType type) {
   2360   CGF.EmitARCDestroyStrong(addr, ARCPreciseLifetime);
   2361 }
   2362 
   2363 void CodeGenFunction::destroyARCStrongImprecise(CodeGenFunction &CGF,
   2364                                                 Address addr,
   2365                                                 QualType type) {
   2366   CGF.EmitARCDestroyStrong(addr, ARCImpreciseLifetime);
   2367 }
   2368 
   2369 void CodeGenFunction::destroyARCWeak(CodeGenFunction &CGF,
   2370                                      Address addr,
   2371                                      QualType type) {
   2372   CGF.EmitARCDestroyWeak(addr);
   2373 }
   2374 
   2375 namespace {
   2376   struct CallObjCAutoreleasePoolObject final : EHScopeStack::Cleanup {
   2377     llvm::Value *Token;
   2378 
   2379     CallObjCAutoreleasePoolObject(llvm::Value *token) : Token(token) {}
   2380 
   2381     void Emit(CodeGenFunction &CGF, Flags flags) override {
   2382       CGF.EmitObjCAutoreleasePoolPop(Token);
   2383     }
   2384   };
   2385   struct CallObjCMRRAutoreleasePoolObject final : EHScopeStack::Cleanup {
   2386     llvm::Value *Token;
   2387 
   2388     CallObjCMRRAutoreleasePoolObject(llvm::Value *token) : Token(token) {}
   2389 
   2390     void Emit(CodeGenFunction &CGF, Flags flags) override {
   2391       CGF.EmitObjCMRRAutoreleasePoolPop(Token);
   2392     }
   2393   };
   2394 }
   2395 
   2396 void CodeGenFunction::EmitObjCAutoreleasePoolCleanup(llvm::Value *Ptr) {
   2397   if (CGM.getLangOpts().ObjCAutoRefCount)
   2398     EHStack.pushCleanup<CallObjCAutoreleasePoolObject>(NormalCleanup, Ptr);
   2399   else
   2400     EHStack.pushCleanup<CallObjCMRRAutoreleasePoolObject>(NormalCleanup, Ptr);
   2401 }
   2402 
   2403 static TryEmitResult tryEmitARCRetainLoadOfScalar(CodeGenFunction &CGF,
   2404                                                   LValue lvalue,
   2405                                                   QualType type) {
   2406   switch (type.getObjCLifetime()) {
   2407   case Qualifiers::OCL_None:
   2408   case Qualifiers::OCL_ExplicitNone:
   2409   case Qualifiers::OCL_Strong:
   2410   case Qualifiers::OCL_Autoreleasing:
   2411     return TryEmitResult(CGF.EmitLoadOfLValue(lvalue,
   2412                                               SourceLocation()).getScalarVal(),
   2413                          false);
   2414 
   2415   case Qualifiers::OCL_Weak:
   2416     return TryEmitResult(CGF.EmitARCLoadWeakRetained(lvalue.getAddress()),
   2417                          true);
   2418   }
   2419 
   2420   llvm_unreachable("impossible lifetime!");
   2421 }
   2422 
   2423 static TryEmitResult tryEmitARCRetainLoadOfScalar(CodeGenFunction &CGF,
   2424                                                   const Expr *e) {
   2425   e = e->IgnoreParens();
   2426   QualType type = e->getType();
   2427 
   2428   // If we're loading retained from a __strong xvalue, we can avoid
   2429   // an extra retain/release pair by zeroing out the source of this
   2430   // "move" operation.
   2431   if (e->isXValue() &&
   2432       !type.isConstQualified() &&
   2433       type.getObjCLifetime() == Qualifiers::OCL_Strong) {
   2434     // Emit the lvalue.
   2435     LValue lv = CGF.EmitLValue(e);
   2436 
   2437     // Load the object pointer.
   2438     llvm::Value *result = CGF.EmitLoadOfLValue(lv,
   2439                                                SourceLocation()).getScalarVal();
   2440 
   2441     // Set the source pointer to NULL.
   2442     CGF.EmitStoreOfScalar(getNullForVariable(lv.getAddress()), lv);
   2443 
   2444     return TryEmitResult(result, true);
   2445   }
   2446 
   2447   // As a very special optimization, in ARC++, if the l-value is the
   2448   // result of a non-volatile assignment, do a simple retain of the
   2449   // result of the call to objc_storeWeak instead of reloading.
   2450   if (CGF.getLangOpts().CPlusPlus &&
   2451       !type.isVolatileQualified() &&
   2452       type.getObjCLifetime() == Qualifiers::OCL_Weak &&
   2453       isa<BinaryOperator>(e) &&
   2454       cast<BinaryOperator>(e)->getOpcode() == BO_Assign)
   2455     return TryEmitResult(CGF.EmitScalarExpr(e), false);
   2456 
   2457   return tryEmitARCRetainLoadOfScalar(CGF, CGF.EmitLValue(e), type);
   2458 }
   2459 
   2460 typedef llvm::function_ref<llvm::Value *(CodeGenFunction &CGF,
   2461                                          llvm::Value *value)>
   2462   ValueTransform;
   2463 
   2464 /// Insert code immediately after a call.
   2465 static llvm::Value *emitARCOperationAfterCall(CodeGenFunction &CGF,
   2466                                               llvm::Value *value,
   2467                                               ValueTransform doAfterCall,
   2468                                               ValueTransform doFallback) {
   2469   if (llvm::CallInst *call = dyn_cast<llvm::CallInst>(value)) {
   2470     CGBuilderTy::InsertPoint ip = CGF.Builder.saveIP();
   2471 
   2472     // Place the retain immediately following the call.
   2473     CGF.Builder.SetInsertPoint(call->getParent(),
   2474                                ++llvm::BasicBlock::iterator(call));
   2475     value = doAfterCall(CGF, value);
   2476 
   2477     CGF.Builder.restoreIP(ip);
   2478     return value;
   2479   } else if (llvm::InvokeInst *invoke = dyn_cast<llvm::InvokeInst>(value)) {
   2480     CGBuilderTy::InsertPoint ip = CGF.Builder.saveIP();
   2481 
   2482     // Place the retain at the beginning of the normal destination block.
   2483     llvm::BasicBlock *BB = invoke->getNormalDest();
   2484     CGF.Builder.SetInsertPoint(BB, BB->begin());
   2485     value = doAfterCall(CGF, value);
   2486 
   2487     CGF.Builder.restoreIP(ip);
   2488     return value;
   2489 
   2490   // Bitcasts can arise because of related-result returns.  Rewrite
   2491   // the operand.
   2492   } else if (llvm::BitCastInst *bitcast = dyn_cast<llvm::BitCastInst>(value)) {
   2493     llvm::Value *operand = bitcast->getOperand(0);
   2494     operand = emitARCOperationAfterCall(CGF, operand, doAfterCall, doFallback);
   2495     bitcast->setOperand(0, operand);
   2496     return bitcast;
   2497 
   2498   // Generic fall-back case.
   2499   } else {
   2500     // Retain using the non-block variant: we never need to do a copy
   2501     // of a block that's been returned to us.
   2502     return doFallback(CGF, value);
   2503   }
   2504 }
   2505 
   2506 /// Given that the given expression is some sort of call (which does
   2507 /// not return retained), emit a retain following it.
   2508 static llvm::Value *emitARCRetainCallResult(CodeGenFunction &CGF,
   2509                                             const Expr *e) {
   2510   llvm::Value *value = CGF.EmitScalarExpr(e);
   2511   return emitARCOperationAfterCall(CGF, value,
   2512            [](CodeGenFunction &CGF, llvm::Value *value) {
   2513              return CGF.EmitARCRetainAutoreleasedReturnValue(value);
   2514            },
   2515            [](CodeGenFunction &CGF, llvm::Value *value) {
   2516              return CGF.EmitARCRetainNonBlock(value);
   2517            });
   2518 }
   2519 
   2520 /// Given that the given expression is some sort of call (which does
   2521 /// not return retained), perform an unsafeClaim following it.
   2522 static llvm::Value *emitARCUnsafeClaimCallResult(CodeGenFunction &CGF,
   2523                                                  const Expr *e) {
   2524   llvm::Value *value = CGF.EmitScalarExpr(e);
   2525   return emitARCOperationAfterCall(CGF, value,
   2526            [](CodeGenFunction &CGF, llvm::Value *value) {
   2527              return CGF.EmitARCUnsafeClaimAutoreleasedReturnValue(value);
   2528            },
   2529            [](CodeGenFunction &CGF, llvm::Value *value) {
   2530              return value;
   2531            });
   2532 }
   2533 
   2534 llvm::Value *CodeGenFunction::EmitARCReclaimReturnedObject(const Expr *E,
   2535                                                       bool allowUnsafeClaim) {
   2536   if (allowUnsafeClaim &&
   2537       CGM.getLangOpts().ObjCRuntime.hasARCUnsafeClaimAutoreleasedReturnValue()) {
   2538     return emitARCUnsafeClaimCallResult(*this, E);
   2539   } else {
   2540     llvm::Value *value = emitARCRetainCallResult(*this, E);
   2541     return EmitObjCConsumeObject(E->getType(), value);
   2542   }
   2543 }
   2544 
   2545 /// Determine whether it might be important to emit a separate
   2546 /// objc_retain_block on the result of the given expression, or
   2547 /// whether it's okay to just emit it in a +1 context.
   2548 static bool shouldEmitSeparateBlockRetain(const Expr *e) {
   2549   assert(e->getType()->isBlockPointerType());
   2550   e = e->IgnoreParens();
   2551 
   2552   // For future goodness, emit block expressions directly in +1
   2553   // contexts if we can.
   2554   if (isa<BlockExpr>(e))
   2555     return false;
   2556 
   2557   if (const CastExpr *cast = dyn_cast<CastExpr>(e)) {
   2558     switch (cast->getCastKind()) {
   2559     // Emitting these operations in +1 contexts is goodness.
   2560     case CK_LValueToRValue:
   2561     case CK_ARCReclaimReturnedObject:
   2562     case CK_ARCConsumeObject:
   2563     case CK_ARCProduceObject:
   2564       return false;
   2565 
   2566     // These operations preserve a block type.
   2567     case CK_NoOp:
   2568     case CK_BitCast:
   2569       return shouldEmitSeparateBlockRetain(cast->getSubExpr());
   2570 
   2571     // These operations are known to be bad (or haven't been considered).
   2572     case CK_AnyPointerToBlockPointerCast:
   2573     default:
   2574       return true;
   2575     }
   2576   }
   2577 
   2578   return true;
   2579 }
   2580 
   2581 namespace {
   2582 /// A CRTP base class for emitting expressions of retainable object
   2583 /// pointer type in ARC.
   2584 template <typename Impl, typename Result> class ARCExprEmitter {
   2585 protected:
   2586   CodeGenFunction &CGF;
   2587   Impl &asImpl() { return *static_cast<Impl*>(this); }
   2588 
   2589   ARCExprEmitter(CodeGenFunction &CGF) : CGF(CGF) {}
   2590 
   2591 public:
   2592   Result visit(const Expr *e);
   2593   Result visitCastExpr(const CastExpr *e);
   2594   Result visitPseudoObjectExpr(const PseudoObjectExpr *e);
   2595   Result visitBinaryOperator(const BinaryOperator *e);
   2596   Result visitBinAssign(const BinaryOperator *e);
   2597   Result visitBinAssignUnsafeUnretained(const BinaryOperator *e);
   2598   Result visitBinAssignAutoreleasing(const BinaryOperator *e);
   2599   Result visitBinAssignWeak(const BinaryOperator *e);
   2600   Result visitBinAssignStrong(const BinaryOperator *e);
   2601 
   2602   // Minimal implementation:
   2603   //   Result visitLValueToRValue(const Expr *e)
   2604   //   Result visitConsumeObject(const Expr *e)
   2605   //   Result visitExtendBlockObject(const Expr *e)
   2606   //   Result visitReclaimReturnedObject(const Expr *e)
   2607   //   Result visitCall(const Expr *e)
   2608   //   Result visitExpr(const Expr *e)
   2609   //
   2610   //   Result emitBitCast(Result result, llvm::Type *resultType)
   2611   //   llvm::Value *getValueOfResult(Result result)
   2612 };
   2613 }
   2614 
   2615 /// Try to emit a PseudoObjectExpr under special ARC rules.
   2616 ///
   2617 /// This massively duplicates emitPseudoObjectRValue.
   2618 template <typename Impl, typename Result>
   2619 Result
   2620 ARCExprEmitter<Impl,Result>::visitPseudoObjectExpr(const PseudoObjectExpr *E) {
   2621   SmallVector<CodeGenFunction::OpaqueValueMappingData, 4> opaques;
   2622 
   2623   // Find the result expression.
   2624   const Expr *resultExpr = E->getResultExpr();
   2625   assert(resultExpr);
   2626   Result result;
   2627 
   2628   for (PseudoObjectExpr::const_semantics_iterator
   2629          i = E->semantics_begin(), e = E->semantics_end(); i != e; ++i) {
   2630     const Expr *semantic = *i;
   2631 
   2632     // If this semantic expression is an opaque value, bind it
   2633     // to the result of its source expression.
   2634     if (const OpaqueValueExpr *ov = dyn_cast<OpaqueValueExpr>(semantic)) {
   2635       typedef CodeGenFunction::OpaqueValueMappingData OVMA;
   2636       OVMA opaqueData;
   2637 
   2638       // If this semantic is the result of the pseudo-object
   2639       // expression, try to evaluate the source as +1.
   2640       if (ov == resultExpr) {
   2641         assert(!OVMA::shouldBindAsLValue(ov));
   2642         result = asImpl().visit(ov->getSourceExpr());
   2643         opaqueData = OVMA::bind(CGF, ov,
   2644                             RValue::get(asImpl().getValueOfResult(result)));
   2645 
   2646       // Otherwise, just bind it.
   2647       } else {
   2648         opaqueData = OVMA::bind(CGF, ov, ov->getSourceExpr());
   2649       }
   2650       opaques.push_back(opaqueData);
   2651 
   2652     // Otherwise, if the expression is the result, evaluate it
   2653     // and remember the result.
   2654     } else if (semantic == resultExpr) {
   2655       result = asImpl().visit(semantic);
   2656 
   2657     // Otherwise, evaluate the expression in an ignored context.
   2658     } else {
   2659       CGF.EmitIgnoredExpr(semantic);
   2660     }
   2661   }
   2662 
   2663   // Unbind all the opaques now.
   2664   for (unsigned i = 0, e = opaques.size(); i != e; ++i)
   2665     opaques[i].unbind(CGF);
   2666 
   2667   return result;
   2668 }
   2669 
   2670 template <typename Impl, typename Result>
   2671 Result ARCExprEmitter<Impl,Result>::visitCastExpr(const CastExpr *e) {
   2672   switch (e->getCastKind()) {
   2673 
   2674   // No-op casts don't change the type, so we just ignore them.
   2675   case CK_NoOp:
   2676     return asImpl().visit(e->getSubExpr());
   2677 
   2678   // These casts can change the type.
   2679   case CK_CPointerToObjCPointerCast:
   2680   case CK_BlockPointerToObjCPointerCast:
   2681   case CK_AnyPointerToBlockPointerCast:
   2682   case CK_BitCast: {
   2683     llvm::Type *resultType = CGF.ConvertType(e->getType());
   2684     assert(e->getSubExpr()->getType()->hasPointerRepresentation());
   2685     Result result = asImpl().visit(e->getSubExpr());
   2686     return asImpl().emitBitCast(result, resultType);
   2687   }
   2688 
   2689   // Handle some casts specially.
   2690   case CK_LValueToRValue:
   2691     return asImpl().visitLValueToRValue(e->getSubExpr());
   2692   case CK_ARCConsumeObject:
   2693     return asImpl().visitConsumeObject(e->getSubExpr());
   2694   case CK_ARCExtendBlockObject:
   2695     return asImpl().visitExtendBlockObject(e->getSubExpr());
   2696   case CK_ARCReclaimReturnedObject:
   2697     return asImpl().visitReclaimReturnedObject(e->getSubExpr());
   2698 
   2699   // Otherwise, use the default logic.
   2700   default:
   2701     return asImpl().visitExpr(e);
   2702   }
   2703 }
   2704 
   2705 template <typename Impl, typename Result>
   2706 Result
   2707 ARCExprEmitter<Impl,Result>::visitBinaryOperator(const BinaryOperator *e) {
   2708   switch (e->getOpcode()) {
   2709   case BO_Comma:
   2710     CGF.EmitIgnoredExpr(e->getLHS());
   2711     CGF.EnsureInsertPoint();
   2712     return asImpl().visit(e->getRHS());
   2713 
   2714   case BO_Assign:
   2715     return asImpl().visitBinAssign(e);
   2716 
   2717   default:
   2718     return asImpl().visitExpr(e);
   2719   }
   2720 }
   2721 
   2722 template <typename Impl, typename Result>
   2723 Result ARCExprEmitter<Impl,Result>::visitBinAssign(const BinaryOperator *e) {
   2724   switch (e->getLHS()->getType().getObjCLifetime()) {
   2725   case Qualifiers::OCL_ExplicitNone:
   2726     return asImpl().visitBinAssignUnsafeUnretained(e);
   2727 
   2728   case Qualifiers::OCL_Weak:
   2729     return asImpl().visitBinAssignWeak(e);
   2730 
   2731   case Qualifiers::OCL_Autoreleasing:
   2732     return asImpl().visitBinAssignAutoreleasing(e);
   2733 
   2734   case Qualifiers::OCL_Strong:
   2735     return asImpl().visitBinAssignStrong(e);
   2736 
   2737   case Qualifiers::OCL_None:
   2738     return asImpl().visitExpr(e);
   2739   }
   2740   llvm_unreachable("bad ObjC ownership qualifier");
   2741 }
   2742 
   2743 /// The default rule for __unsafe_unretained emits the RHS recursively,
   2744 /// stores into the unsafe variable, and propagates the result outward.
   2745 template <typename Impl, typename Result>
   2746 Result ARCExprEmitter<Impl,Result>::
   2747                     visitBinAssignUnsafeUnretained(const BinaryOperator *e) {
   2748   // Recursively emit the RHS.
   2749   // For __block safety, do this before emitting the LHS.
   2750   Result result = asImpl().visit(e->getRHS());
   2751 
   2752   // Perform the store.
   2753   LValue lvalue =
   2754     CGF.EmitCheckedLValue(e->getLHS(), CodeGenFunction::TCK_Store);
   2755   CGF.EmitStoreThroughLValue(RValue::get(asImpl().getValueOfResult(result)),
   2756                              lvalue);
   2757 
   2758   return result;
   2759 }
   2760 
   2761 template <typename Impl, typename Result>
   2762 Result
   2763 ARCExprEmitter<Impl,Result>::visitBinAssignAutoreleasing(const BinaryOperator *e) {
   2764   return asImpl().visitExpr(e);
   2765 }
   2766 
   2767 template <typename Impl, typename Result>
   2768 Result
   2769 ARCExprEmitter<Impl,Result>::visitBinAssignWeak(const BinaryOperator *e) {
   2770   return asImpl().visitExpr(e);
   2771 }
   2772 
   2773 template <typename Impl, typename Result>
   2774 Result
   2775 ARCExprEmitter<Impl,Result>::visitBinAssignStrong(const BinaryOperator *e) {
   2776   return asImpl().visitExpr(e);
   2777 }
   2778 
   2779 /// The general expression-emission logic.
   2780 template <typename Impl, typename Result>
   2781 Result ARCExprEmitter<Impl,Result>::visit(const Expr *e) {
   2782   // We should *never* see a nested full-expression here, because if
   2783   // we fail to emit at +1, our caller must not retain after we close
   2784   // out the full-expression.  This isn't as important in the unsafe
   2785   // emitter.
   2786   assert(!isa<ExprWithCleanups>(e));
   2787 
   2788   // Look through parens, __extension__, generic selection, etc.
   2789   e = e->IgnoreParens();
   2790 
   2791   // Handle certain kinds of casts.
   2792   if (const CastExpr *ce = dyn_cast<CastExpr>(e)) {
   2793     return asImpl().visitCastExpr(ce);
   2794 
   2795   // Handle the comma operator.
   2796   } else if (auto op = dyn_cast<BinaryOperator>(e)) {
   2797     return asImpl().visitBinaryOperator(op);
   2798 
   2799   // TODO: handle conditional operators here
   2800 
   2801   // For calls and message sends, use the retained-call logic.
   2802   // Delegate inits are a special case in that they're the only
   2803   // returns-retained expression that *isn't* surrounded by
   2804   // a consume.
   2805   } else if (isa<CallExpr>(e) ||
   2806              (isa<ObjCMessageExpr>(e) &&
   2807               !cast<ObjCMessageExpr>(e)->isDelegateInitCall())) {
   2808     return asImpl().visitCall(e);
   2809 
   2810   // Look through pseudo-object expressions.
   2811   } else if (const PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
   2812     return asImpl().visitPseudoObjectExpr(pseudo);
   2813   }
   2814 
   2815   return asImpl().visitExpr(e);
   2816 }
   2817 
   2818 namespace {
   2819 
   2820 /// An emitter for +1 results.
   2821 struct ARCRetainExprEmitter :
   2822   public ARCExprEmitter<ARCRetainExprEmitter, TryEmitResult> {
   2823 
   2824   ARCRetainExprEmitter(CodeGenFunction &CGF) : ARCExprEmitter(CGF) {}
   2825 
   2826   llvm::Value *getValueOfResult(TryEmitResult result) {
   2827     return result.getPointer();
   2828   }
   2829 
   2830   TryEmitResult emitBitCast(TryEmitResult result, llvm::Type *resultType) {
   2831     llvm::Value *value = result.getPointer();
   2832     value = CGF.Builder.CreateBitCast(value, resultType);
   2833     result.setPointer(value);
   2834     return result;
   2835   }
   2836 
   2837   TryEmitResult visitLValueToRValue(const Expr *e) {
   2838     return tryEmitARCRetainLoadOfScalar(CGF, e);
   2839   }
   2840 
   2841   /// For consumptions, just emit the subexpression and thus elide
   2842   /// the retain/release pair.
   2843   TryEmitResult visitConsumeObject(const Expr *e) {
   2844     llvm::Value *result = CGF.EmitScalarExpr(e);
   2845     return TryEmitResult(result, true);
   2846   }
   2847 
   2848   /// Block extends are net +0.  Naively, we could just recurse on
   2849   /// the subexpression, but actually we need to ensure that the
   2850   /// value is copied as a block, so there's a little filter here.
   2851   TryEmitResult visitExtendBlockObject(const Expr *e) {
   2852     llvm::Value *result; // will be a +0 value
   2853 
   2854     // If we can't safely assume the sub-expression will produce a
   2855     // block-copied value, emit the sub-expression at +0.
   2856     if (shouldEmitSeparateBlockRetain(e)) {
   2857       result = CGF.EmitScalarExpr(e);
   2858 
   2859     // Otherwise, try to emit the sub-expression at +1 recursively.
   2860     } else {
   2861       TryEmitResult subresult = asImpl().visit(e);
   2862 
   2863       // If that produced a retained value, just use that.
   2864       if (subresult.getInt()) {
   2865         return subresult;
   2866       }
   2867 
   2868       // Otherwise it's +0.
   2869       result = subresult.getPointer();
   2870     }
   2871 
   2872     // Retain the object as a block.
   2873     result = CGF.EmitARCRetainBlock(result, /*mandatory*/ true);
   2874     return TryEmitResult(result, true);
   2875   }
   2876 
   2877   /// For reclaims, emit the subexpression as a retained call and
   2878   /// skip the consumption.
   2879   TryEmitResult visitReclaimReturnedObject(const Expr *e) {
   2880     llvm::Value *result = emitARCRetainCallResult(CGF, e);
   2881     return TryEmitResult(result, true);
   2882   }
   2883 
   2884   /// When we have an undecorated call, retroactively do a claim.
   2885   TryEmitResult visitCall(const Expr *e) {
   2886     llvm::Value *result = emitARCRetainCallResult(CGF, e);
   2887     return TryEmitResult(result, true);
   2888   }
   2889 
   2890   // TODO: maybe special-case visitBinAssignWeak?
   2891 
   2892   TryEmitResult visitExpr(const Expr *e) {
   2893     // We didn't find an obvious production, so emit what we've got and
   2894     // tell the caller that we didn't manage to retain.
   2895     llvm::Value *result = CGF.EmitScalarExpr(e);
   2896     return TryEmitResult(result, false);
   2897   }
   2898 };
   2899 }
   2900 
   2901 static TryEmitResult
   2902 tryEmitARCRetainScalarExpr(CodeGenFunction &CGF, const Expr *e) {
   2903   return ARCRetainExprEmitter(CGF).visit(e);
   2904 }
   2905 
   2906 static llvm::Value *emitARCRetainLoadOfScalar(CodeGenFunction &CGF,
   2907                                                 LValue lvalue,
   2908                                                 QualType type) {
   2909   TryEmitResult result = tryEmitARCRetainLoadOfScalar(CGF, lvalue, type);
   2910   llvm::Value *value = result.getPointer();
   2911   if (!result.getInt())
   2912     value = CGF.EmitARCRetain(type, value);
   2913   return value;
   2914 }
   2915 
   2916 /// EmitARCRetainScalarExpr - Semantically equivalent to
   2917 /// EmitARCRetainObject(e->getType(), EmitScalarExpr(e)), but making a
   2918 /// best-effort attempt to peephole expressions that naturally produce
   2919 /// retained objects.
   2920 llvm::Value *CodeGenFunction::EmitARCRetainScalarExpr(const Expr *e) {
   2921   // The retain needs to happen within the full-expression.
   2922   if (const ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(e)) {
   2923     enterFullExpression(cleanups);
   2924     RunCleanupsScope scope(*this);
   2925     return EmitARCRetainScalarExpr(cleanups->getSubExpr());
   2926   }
   2927 
   2928   TryEmitResult result = tryEmitARCRetainScalarExpr(*this, e);
   2929   llvm::Value *value = result.getPointer();
   2930   if (!result.getInt())
   2931     value = EmitARCRetain(e->getType(), value);
   2932   return value;
   2933 }
   2934 
   2935 llvm::Value *
   2936 CodeGenFunction::EmitARCRetainAutoreleaseScalarExpr(const Expr *e) {
   2937   // The retain needs to happen within the full-expression.
   2938   if (const ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(e)) {
   2939     enterFullExpression(cleanups);
   2940     RunCleanupsScope scope(*this);
   2941     return EmitARCRetainAutoreleaseScalarExpr(cleanups->getSubExpr());
   2942   }
   2943 
   2944   TryEmitResult result = tryEmitARCRetainScalarExpr(*this, e);
   2945   llvm::Value *value = result.getPointer();
   2946   if (result.getInt())
   2947     value = EmitARCAutorelease(value);
   2948   else
   2949     value = EmitARCRetainAutorelease(e->getType(), value);
   2950   return value;
   2951 }
   2952 
   2953 llvm::Value *CodeGenFunction::EmitARCExtendBlockObject(const Expr *e) {
   2954   llvm::Value *result;
   2955   bool doRetain;
   2956 
   2957   if (shouldEmitSeparateBlockRetain(e)) {
   2958     result = EmitScalarExpr(e);
   2959     doRetain = true;
   2960   } else {
   2961     TryEmitResult subresult = tryEmitARCRetainScalarExpr(*this, e);
   2962     result = subresult.getPointer();
   2963     doRetain = !subresult.getInt();
   2964   }
   2965 
   2966   if (doRetain)
   2967     result = EmitARCRetainBlock(result, /*mandatory*/ true);
   2968   return EmitObjCConsumeObject(e->getType(), result);
   2969 }
   2970 
   2971 llvm::Value *CodeGenFunction::EmitObjCThrowOperand(const Expr *expr) {
   2972   // In ARC, retain and autorelease the expression.
   2973   if (getLangOpts().ObjCAutoRefCount) {
   2974     // Do so before running any cleanups for the full-expression.
   2975     // EmitARCRetainAutoreleaseScalarExpr does this for us.
   2976     return EmitARCRetainAutoreleaseScalarExpr(expr);
   2977   }
   2978 
   2979   // Otherwise, use the normal scalar-expression emission.  The
   2980   // exception machinery doesn't do anything special with the
   2981   // exception like retaining it, so there's no safety associated with
   2982   // only running cleanups after the throw has started, and when it
   2983   // matters it tends to be substantially inferior code.
   2984   return EmitScalarExpr(expr);
   2985 }
   2986 
   2987 namespace {
   2988 
   2989 /// An emitter for assigning into an __unsafe_unretained context.
   2990 struct ARCUnsafeUnretainedExprEmitter :
   2991   public ARCExprEmitter<ARCUnsafeUnretainedExprEmitter, llvm::Value*> {
   2992 
   2993   ARCUnsafeUnretainedExprEmitter(CodeGenFunction &CGF) : ARCExprEmitter(CGF) {}
   2994 
   2995   llvm::Value *getValueOfResult(llvm::Value *value) {
   2996     return value;
   2997   }
   2998 
   2999   llvm::Value *emitBitCast(llvm::Value *value, llvm::Type *resultType) {
   3000     return CGF.Builder.CreateBitCast(value, resultType);
   3001   }
   3002 
   3003   llvm::Value *visitLValueToRValue(const Expr *e) {
   3004     return CGF.EmitScalarExpr(e);
   3005   }
   3006 
   3007   /// For consumptions, just emit the subexpression and perform the
   3008   /// consumption like normal.
   3009   llvm::Value *visitConsumeObject(const Expr *e) {
   3010     llvm::Value *value = CGF.EmitScalarExpr(e);
   3011     return CGF.EmitObjCConsumeObject(e->getType(), value);
   3012   }
   3013 
   3014   /// No special logic for block extensions.  (This probably can't
   3015   /// actually happen in this emitter, though.)
   3016   llvm::Value *visitExtendBlockObject(const Expr *e) {
   3017     return CGF.EmitARCExtendBlockObject(e);
   3018   }
   3019 
   3020   /// For reclaims, perform an unsafeClaim if that's enabled.
   3021   llvm::Value *visitReclaimReturnedObject(const Expr *e) {
   3022     return CGF.EmitARCReclaimReturnedObject(e, /*unsafe*/ true);
   3023   }
   3024 
   3025   /// When we have an undecorated call, just emit it without adding
   3026   /// the unsafeClaim.
   3027   llvm::Value *visitCall(const Expr *e) {
   3028     return CGF.EmitScalarExpr(e);
   3029   }
   3030 
   3031   /// Just do normal scalar emission in the default case.
   3032   llvm::Value *visitExpr(const Expr *e) {
   3033     return CGF.EmitScalarExpr(e);
   3034   }
   3035 };
   3036 }
   3037 
   3038 static llvm::Value *emitARCUnsafeUnretainedScalarExpr(CodeGenFunction &CGF,
   3039                                                       const Expr *e) {
   3040   return ARCUnsafeUnretainedExprEmitter(CGF).visit(e);
   3041 }
   3042 
   3043 /// EmitARCUnsafeUnretainedScalarExpr - Semantically equivalent to
   3044 /// immediately releasing the resut of EmitARCRetainScalarExpr, but
   3045 /// avoiding any spurious retains, including by performing reclaims
   3046 /// with objc_unsafeClaimAutoreleasedReturnValue.
   3047 llvm::Value *CodeGenFunction::EmitARCUnsafeUnretainedScalarExpr(const Expr *e) {
   3048   // Look through full-expressions.
   3049   if (const ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(e)) {
   3050     enterFullExpression(cleanups);
   3051     RunCleanupsScope scope(*this);
   3052     return emitARCUnsafeUnretainedScalarExpr(*this, cleanups->getSubExpr());
   3053   }
   3054 
   3055   return emitARCUnsafeUnretainedScalarExpr(*this, e);
   3056 }
   3057 
   3058 std::pair<LValue,llvm::Value*>
   3059 CodeGenFunction::EmitARCStoreUnsafeUnretained(const BinaryOperator *e,
   3060                                               bool ignored) {
   3061   // Evaluate the RHS first.  If we're ignoring the result, assume
   3062   // that we can emit at an unsafe +0.
   3063   llvm::Value *value;
   3064   if (ignored) {
   3065     value = EmitARCUnsafeUnretainedScalarExpr(e->getRHS());
   3066   } else {
   3067     value = EmitScalarExpr(e->getRHS());
   3068   }
   3069 
   3070   // Emit the LHS and perform the store.
   3071   LValue lvalue = EmitLValue(e->getLHS());
   3072   EmitStoreOfScalar(value, lvalue);
   3073 
   3074   return std::pair<LValue,llvm::Value*>(std::move(lvalue), value);
   3075 }
   3076 
   3077 std::pair<LValue,llvm::Value*>
   3078 CodeGenFunction::EmitARCStoreStrong(const BinaryOperator *e,
   3079                                     bool ignored) {
   3080   // Evaluate the RHS first.
   3081   TryEmitResult result = tryEmitARCRetainScalarExpr(*this, e->getRHS());
   3082   llvm::Value *value = result.getPointer();
   3083 
   3084   bool hasImmediateRetain = result.getInt();
   3085 
   3086   // If we didn't emit a retained object, and the l-value is of block
   3087   // type, then we need to emit the block-retain immediately in case
   3088   // it invalidates the l-value.
   3089   if (!hasImmediateRetain && e->getType()->isBlockPointerType()) {
   3090     value = EmitARCRetainBlock(value, /*mandatory*/ false);
   3091     hasImmediateRetain = true;
   3092   }
   3093 
   3094   LValue lvalue = EmitLValue(e->getLHS());
   3095 
   3096   // If the RHS was emitted retained, expand this.
   3097   if (hasImmediateRetain) {
   3098     llvm::Value *oldValue = EmitLoadOfScalar(lvalue, SourceLocation());
   3099     EmitStoreOfScalar(value, lvalue);
   3100     EmitARCRelease(oldValue, lvalue.isARCPreciseLifetime());
   3101   } else {
   3102     value = EmitARCStoreStrong(lvalue, value, ignored);
   3103   }
   3104 
   3105   return std::pair<LValue,llvm::Value*>(lvalue, value);
   3106 }
   3107 
   3108 std::pair<LValue,llvm::Value*>
   3109 CodeGenFunction::EmitARCStoreAutoreleasing(const BinaryOperator *e) {
   3110   llvm::Value *value = EmitARCRetainAutoreleaseScalarExpr(e->getRHS());
   3111   LValue lvalue = EmitLValue(e->getLHS());
   3112 
   3113   EmitStoreOfScalar(value, lvalue);
   3114 
   3115   return std::pair<LValue,llvm::Value*>(lvalue, value);
   3116 }
   3117 
   3118 void CodeGenFunction::EmitObjCAutoreleasePoolStmt(
   3119                                           const ObjCAutoreleasePoolStmt &ARPS) {
   3120   const Stmt *subStmt = ARPS.getSubStmt();
   3121   const CompoundStmt &S = cast<CompoundStmt>(*subStmt);
   3122 
   3123   CGDebugInfo *DI = getDebugInfo();
   3124   if (DI)
   3125     DI->EmitLexicalBlockStart(Builder, S.getLBracLoc());
   3126 
   3127   // Keep track of the current cleanup stack depth.
   3128   RunCleanupsScope Scope(*this);
   3129   if (CGM.getLangOpts().ObjCRuntime.hasNativeARC()) {
   3130     llvm::Value *token = EmitObjCAutoreleasePoolPush();
   3131     EHStack.pushCleanup<CallObjCAutoreleasePoolObject>(NormalCleanup, token);
   3132   } else {
   3133     llvm::Value *token = EmitObjCMRRAutoreleasePoolPush();
   3134     EHStack.pushCleanup<CallObjCMRRAutoreleasePoolObject>(NormalCleanup, token);
   3135   }
   3136 
   3137   for (const auto *I : S.body())
   3138     EmitStmt(I);
   3139 
   3140   if (DI)
   3141     DI->EmitLexicalBlockEnd(Builder, S.getRBracLoc());
   3142 }
   3143 
   3144 /// EmitExtendGCLifetime - Given a pointer to an Objective-C object,
   3145 /// make sure it survives garbage collection until this point.
   3146 void CodeGenFunction::EmitExtendGCLifetime(llvm::Value *object) {
   3147   // We just use an inline assembly.
   3148   llvm::FunctionType *extenderType
   3149     = llvm::FunctionType::get(VoidTy, VoidPtrTy, RequiredArgs::All);
   3150   llvm::Value *extender
   3151     = llvm::InlineAsm::get(extenderType,
   3152                            /* assembly */ "",
   3153                            /* constraints */ "r",
   3154                            /* side effects */ true);
   3155 
   3156   object = Builder.CreateBitCast(object, VoidPtrTy);
   3157   EmitNounwindRuntimeCall(extender, object);
   3158 }
   3159 
   3160 /// GenerateObjCAtomicSetterCopyHelperFunction - Given a c++ object type with
   3161 /// non-trivial copy assignment function, produce following helper function.
   3162 /// static void copyHelper(Ty *dest, const Ty *source) { *dest = *source; }
   3163 ///
   3164 llvm::Constant *
   3165 CodeGenFunction::GenerateObjCAtomicSetterCopyHelperFunction(
   3166                                         const ObjCPropertyImplDecl *PID) {
   3167   if (!getLangOpts().CPlusPlus ||
   3168       !getLangOpts().ObjCRuntime.hasAtomicCopyHelper())
   3169     return nullptr;
   3170   QualType Ty = PID->getPropertyIvarDecl()->getType();
   3171   if (!Ty->isRecordType())
   3172     return nullptr;
   3173   const ObjCPropertyDecl *PD = PID->getPropertyDecl();
   3174   if ((!(PD->getPropertyAttributes() & ObjCPropertyDecl::OBJC_PR_atomic)))
   3175     return nullptr;
   3176   llvm::Constant *HelperFn = nullptr;
   3177   if (hasTrivialSetExpr(PID))
   3178     return nullptr;
   3179   assert(PID->getSetterCXXAssignment() && "SetterCXXAssignment - null");
   3180   if ((HelperFn = CGM.getAtomicSetterHelperFnMap(Ty)))
   3181     return HelperFn;
   3182 
   3183   ASTContext &C = getContext();
   3184   IdentifierInfo *II
   3185     = &CGM.getContext().Idents.get("__assign_helper_atomic_property_");
   3186   FunctionDecl *FD = FunctionDecl::Create(C,
   3187                                           C.getTranslationUnitDecl(),
   3188                                           SourceLocation(),
   3189                                           SourceLocation(), II, C.VoidTy,
   3190                                           nullptr, SC_Static,
   3191                                           false,
   3192                                           false);
   3193 
   3194   QualType DestTy = C.getPointerType(Ty);
   3195   QualType SrcTy = Ty;
   3196   SrcTy.addConst();
   3197   SrcTy = C.getPointerType(SrcTy);
   3198 
   3199   FunctionArgList args;
   3200   ImplicitParamDecl dstDecl(getContext(), FD, SourceLocation(), nullptr,DestTy);
   3201   args.push_back(&dstDecl);
   3202   ImplicitParamDecl srcDecl(getContext(), FD, SourceLocation(), nullptr, SrcTy);
   3203   args.push_back(&srcDecl);
   3204 
   3205   const CGFunctionInfo &FI =
   3206     CGM.getTypes().arrangeBuiltinFunctionDeclaration(C.VoidTy, args);
   3207 
   3208   llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
   3209 
   3210   llvm::Function *Fn =
   3211     llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
   3212                            "__assign_helper_atomic_property_",
   3213                            &CGM.getModule());
   3214 
   3215   CGM.SetInternalFunctionAttributes(nullptr, Fn, FI);
   3216 
   3217   StartFunction(FD, C.VoidTy, Fn, FI, args);
   3218 
   3219   DeclRefExpr DstExpr(&dstDecl, false, DestTy,
   3220                       VK_RValue, SourceLocation());
   3221   UnaryOperator DST(&DstExpr, UO_Deref, DestTy->getPointeeType(),
   3222                     VK_LValue, OK_Ordinary, SourceLocation());
   3223 
   3224   DeclRefExpr SrcExpr(&srcDecl, false, SrcTy,
   3225                       VK_RValue, SourceLocation());
   3226   UnaryOperator SRC(&SrcExpr, UO_Deref, SrcTy->getPointeeType(),
   3227                     VK_LValue, OK_Ordinary, SourceLocation());
   3228 
   3229   Expr *Args[2] = { &DST, &SRC };
   3230   CallExpr *CalleeExp = cast<CallExpr>(PID->getSetterCXXAssignment());
   3231   CXXOperatorCallExpr TheCall(C, OO_Equal, CalleeExp->getCallee(),
   3232                               Args, DestTy->getPointeeType(),
   3233                               VK_LValue, SourceLocation(), false);
   3234 
   3235   EmitStmt(&TheCall);
   3236 
   3237   FinishFunction();
   3238   HelperFn = llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
   3239   CGM.setAtomicSetterHelperFnMap(Ty, HelperFn);
   3240   return HelperFn;
   3241 }
   3242 
   3243 llvm::Constant *
   3244 CodeGenFunction::GenerateObjCAtomicGetterCopyHelperFunction(
   3245                                             const ObjCPropertyImplDecl *PID) {
   3246   if (!getLangOpts().CPlusPlus ||
   3247       !getLangOpts().ObjCRuntime.hasAtomicCopyHelper())
   3248     return nullptr;
   3249   const ObjCPropertyDecl *PD = PID->getPropertyDecl();
   3250   QualType Ty = PD->getType();
   3251   if (!Ty->isRecordType())
   3252     return nullptr;
   3253   if ((!(PD->getPropertyAttributes() & ObjCPropertyDecl::OBJC_PR_atomic)))
   3254     return nullptr;
   3255   llvm::Constant *HelperFn = nullptr;
   3256 
   3257   if (hasTrivialGetExpr(PID))
   3258     return nullptr;
   3259   assert(PID->getGetterCXXConstructor() && "getGetterCXXConstructor - null");
   3260   if ((HelperFn = CGM.getAtomicGetterHelperFnMap(Ty)))
   3261     return HelperFn;
   3262 
   3263 
   3264   ASTContext &C = getContext();
   3265   IdentifierInfo *II
   3266   = &CGM.getContext().Idents.get("__copy_helper_atomic_property_");
   3267   FunctionDecl *FD = FunctionDecl::Create(C,
   3268                                           C.getTranslationUnitDecl(),
   3269                                           SourceLocation(),
   3270                                           SourceLocation(), II, C.VoidTy,
   3271                                           nullptr, SC_Static,
   3272                                           false,
   3273                                           false);
   3274 
   3275   QualType DestTy = C.getPointerType(Ty);
   3276   QualType SrcTy = Ty;
   3277   SrcTy.addConst();
   3278   SrcTy = C.getPointerType(SrcTy);
   3279 
   3280   FunctionArgList args;
   3281   ImplicitParamDecl dstDecl(getContext(), FD, SourceLocation(), nullptr,DestTy);
   3282   args.push_back(&dstDecl);
   3283   ImplicitParamDecl srcDecl(getContext(), FD, SourceLocation(), nullptr, SrcTy);
   3284   args.push_back(&srcDecl);
   3285 
   3286   const CGFunctionInfo &FI =
   3287     CGM.getTypes().arrangeBuiltinFunctionDeclaration(C.VoidTy, args);
   3288 
   3289   llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
   3290 
   3291   llvm::Function *Fn =
   3292   llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
   3293                          "__copy_helper_atomic_property_", &CGM.getModule());
   3294 
   3295   CGM.SetInternalFunctionAttributes(nullptr, Fn, FI);
   3296 
   3297   StartFunction(FD, C.VoidTy, Fn, FI, args);
   3298 
   3299   DeclRefExpr SrcExpr(&srcDecl, false, SrcTy,
   3300                       VK_RValue, SourceLocation());
   3301 
   3302   UnaryOperator SRC(&SrcExpr, UO_Deref, SrcTy->getPointeeType(),
   3303                     VK_LValue, OK_Ordinary, SourceLocation());
   3304 
   3305   CXXConstructExpr *CXXConstExpr =
   3306     cast<CXXConstructExpr>(PID->getGetterCXXConstructor());
   3307 
   3308   SmallVector<Expr*, 4> ConstructorArgs;
   3309   ConstructorArgs.push_back(&SRC);
   3310   ConstructorArgs.append(std::next(CXXConstExpr->arg_begin()),
   3311                          CXXConstExpr->arg_end());
   3312 
   3313   CXXConstructExpr *TheCXXConstructExpr =
   3314     CXXConstructExpr::Create(C, Ty, SourceLocation(),
   3315                              CXXConstExpr->getConstructor(),
   3316                              CXXConstExpr->isElidable(),
   3317                              ConstructorArgs,
   3318                              CXXConstExpr->hadMultipleCandidates(),
   3319                              CXXConstExpr->isListInitialization(),
   3320                              CXXConstExpr->isStdInitListInitialization(),
   3321                              CXXConstExpr->requiresZeroInitialization(),
   3322                              CXXConstExpr->getConstructionKind(),
   3323                              SourceRange());
   3324 
   3325   DeclRefExpr DstExpr(&dstDecl, false, DestTy,
   3326                       VK_RValue, SourceLocation());
   3327 
   3328   RValue DV = EmitAnyExpr(&DstExpr);
   3329   CharUnits Alignment
   3330     = getContext().getTypeAlignInChars(TheCXXConstructExpr->getType());
   3331   EmitAggExpr(TheCXXConstructExpr,
   3332               AggValueSlot::forAddr(Address(DV.getScalarVal(), Alignment),
   3333                                     Qualifiers(),
   3334                                     AggValueSlot::IsDestructed,
   3335                                     AggValueSlot::DoesNotNeedGCBarriers,
   3336                                     AggValueSlot::IsNotAliased));
   3337 
   3338   FinishFunction();
   3339   HelperFn = llvm::ConstantExpr::getBitCast(Fn, VoidPtrTy);
   3340   CGM.setAtomicGetterHelperFnMap(Ty, HelperFn);
   3341   return HelperFn;
   3342 }
   3343 
   3344 llvm::Value *
   3345 CodeGenFunction::EmitBlockCopyAndAutorelease(llvm::Value *Block, QualType Ty) {
   3346   // Get selectors for retain/autorelease.
   3347   IdentifierInfo *CopyID = &getContext().Idents.get("copy");
   3348   Selector CopySelector =
   3349       getContext().Selectors.getNullarySelector(CopyID);
   3350   IdentifierInfo *AutoreleaseID = &getContext().Idents.get("autorelease");
   3351   Selector AutoreleaseSelector =
   3352       getContext().Selectors.getNullarySelector(AutoreleaseID);
   3353 
   3354   // Emit calls to retain/autorelease.
   3355   CGObjCRuntime &Runtime = CGM.getObjCRuntime();
   3356   llvm::Value *Val = Block;
   3357   RValue Result;
   3358   Result = Runtime.GenerateMessageSend(*this, ReturnValueSlot(),
   3359                                        Ty, CopySelector,
   3360                                        Val, CallArgList(), nullptr, nullptr);
   3361   Val = Result.getScalarVal();
   3362   Result = Runtime.GenerateMessageSend(*this, ReturnValueSlot(),
   3363                                        Ty, AutoreleaseSelector,
   3364                                        Val, CallArgList(), nullptr, nullptr);
   3365   Val = Result.getScalarVal();
   3366   return Val;
   3367 }
   3368 
   3369 
   3370 CGObjCRuntime::~CGObjCRuntime() {}
   3371