CGClass.cpp

    return;

  // The complete-destructor phase just destructs all the virtual bases.
  if (DtorType == Dtor_Complete) {

    // We push them in the forward order so that they'll be popped in
    // the reverse order.
    for (CXXRecordDecl::base_class_const_iterator I = 
           ClassDecl->vbases_begin(), E = ClassDecl->vbases_end();
              I != E; ++I) {
      const CXXBaseSpecifier &Base = *I;
      CXXRecordDecl *BaseClassDecl
        = cast<CXXRecordDecl>(Base.getType()->getAs<RecordType>()->getDecl());
    
      // Ignore trivial destructors.
      if (BaseClassDecl->hasTrivialDestructor())
        continue;

      EHStack.pushCleanup<CallBaseDtor>(NormalAndEHCleanup,
                                        BaseClassDecl,
                                        /*BaseIsVirtual*/ true);
    }

    return;
  }

  assert(DtorType == Dtor_Base);
  
  // Destroy non-virtual bases.
  for (CXXRecordDecl::base_class_const_iterator I = 
        ClassDecl->bases_begin(), E = ClassDecl->bases_end(); I != E; ++I) {
    const CXXBaseSpecifier &Base = *I;
    
    // Ignore virtual bases.
    if (Base.isVirtual())
      continue;
    
    CXXRecordDecl *BaseClassDecl = Base.getType()->getAsCXXRecordDecl();
    
    // Ignore trivial destructors.
    if (BaseClassDecl->hasTrivialDestructor())
      continue;

    EHStack.pushCleanup<CallBaseDtor>(NormalAndEHCleanup,
                                      BaseClassDecl,
                                      /*BaseIsVirtual*/ false);
  }

  // Destroy direct fields.
  SmallVector<const FieldDecl *, 16> FieldDecls;
  for (CXXRecordDecl::field_iterator I = ClassDecl->field_begin(),
       E = ClassDecl->field_end(); I != E; ++I) {
    const FieldDecl *field = *I;
    QualType type = field->getType();
    QualType::DestructionKind dtorKind = type.isDestructedType();
    if (!dtorKind) continue;

    CleanupKind cleanupKind = getCleanupKind(dtorKind);
    EHStack.pushCleanup<DestroyField>(cleanupKind, field,
                                      getDestroyer(dtorKind),
                                      cleanupKind & EHCleanup);
  }
}

/// EmitCXXAggrConstructorCall - Emit a loop to call a particular
/// constructor for each of several members of an array.
///
/// \param ctor the constructor to call for each element
/// \param argBegin,argEnd the arguments to evaluate and pass to the
///   constructor
/// \param arrayType the type of the array to initialize
/// \param arrayBegin an arrayType*
/// \param zeroInitialize true if each element should be
///   zero-initialized before it is constructed
void
CodeGenFunction::EmitCXXAggrConstructorCall(const CXXConstructorDecl *ctor,
                                            const ConstantArrayType *arrayType,
                                            llvm::Value *arrayBegin,
                                          CallExpr::const_arg_iterator argBegin,
                                            CallExpr::const_arg_iterator argEnd,
                                            bool zeroInitialize) {
  QualType elementType;
  llvm::Value *numElements =
    emitArrayLength(arrayType, elementType, arrayBegin);

  EmitCXXAggrConstructorCall(ctor, numElements, arrayBegin,
                             argBegin, argEnd, zeroInitialize);
}

/// EmitCXXAggrConstructorCall - Emit a loop to call a particular
/// constructor for each of several members of an array.
///
/// \param ctor the constructor to call for each element
/// \param numElements the number of elements in the array;
///   may be zero
/// \param argBegin,argEnd the arguments to evaluate and pass to the
///   constructor
/// \param arrayBegin a T*, where T is the type constructed by ctor
/// \param zeroInitialize true if each element should be
///   zero-initialized before it is constructed
void
CodeGenFunction::EmitCXXAggrConstructorCall(const CXXConstructorDecl *ctor,
                                            llvm::Value *numElements,
                                            llvm::Value *arrayBegin,
                                         CallExpr::const_arg_iterator argBegin,
                                           CallExpr::const_arg_iterator argEnd,
                                            bool zeroInitialize) {

  // It's legal for numElements to be zero.  This can happen both
  // dynamically, because x can be zero in 'new A[x]', and statically,
  // because of GCC extensions that permit zero-length arrays.  There
  // are probably legitimate places where we could assume that this
  // doesn't happen, but it's not clear that it's worth it.
  llvm::BranchInst *zeroCheckBranch = 0;

  // Optimize for a constant count.
  llvm::ConstantInt *constantCount
    = dyn_cast<llvm::ConstantInt>(numElements);
  if (constantCount) {
    // Just skip out if the constant count is zero.
    if (constantCount->isZero()) return;

  // Otherwise, emit the check.
  } else {
    llvm::BasicBlock *loopBB = createBasicBlock("new.ctorloop");
    llvm::Value *iszero = Builder.CreateIsNull(numElements, "isempty");
    zeroCheckBranch = Builder.CreateCondBr(iszero, loopBB, loopBB);
    EmitBlock(loopBB);
  }
      
  // Find the end of the array.
  llvm::Value *arrayEnd = Builder.CreateInBoundsGEP(arrayBegin, numElements,
                                                    "arrayctor.end");

  // Enter the loop, setting up a phi for the current location to initialize.
  llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
  llvm::BasicBlock *loopBB = createBasicBlock("arrayctor.loop");
  EmitBlock(loopBB);
  llvm::PHINode *cur = Builder.CreatePHI(arrayBegin->getType(), 2,
                                         "arrayctor.cur");
  cur->addIncoming(arrayBegin, entryBB);

  // Inside the loop body, emit the constructor call on the array element.

  QualType type = getContext().getTypeDeclType(ctor->getParent());

  // Zero initialize the storage, if requested.
  if (zeroInitialize)
    EmitNullInitialization(cur, type);
  
  // C++ [class.temporary]p4: 
  // There are two contexts in which temporaries are destroyed at a different
  // point than the end of the full-expression. The first context is when a
  // default constructor is called to initialize an element of an array. 
  // If the constructor has one or more default arguments, the destruction of 
  // every temporary created in a default argument expression is sequenced 
  // before the construction of the next array element, if any.
  
  {
    RunCleanupsScope Scope(*this);

    // Evaluate the constructor and its arguments in a regular
    // partial-destroy cleanup.
    if (getLangOptions().Exceptions &&
        !ctor->getParent()->hasTrivialDestructor()) {
      Destroyer *destroyer = destroyCXXObject;
      pushRegularPartialArrayCleanup(arrayBegin, cur, type, *destroyer);
    }

    EmitCXXConstructorCall(ctor, Ctor_Complete, /*ForVirtualBase=*/ false,
                           cur, argBegin, argEnd);
  }

  // Go to the next element.
  llvm::Value *next =
    Builder.CreateInBoundsGEP(cur, llvm::ConstantInt::get(SizeTy, 1),
                              "arrayctor.next");
  cur->addIncoming(next, Builder.GetInsertBlock());

  // Check whether that's the end of the loop.
  llvm::Value *done = Builder.CreateICmpEQ(next, arrayEnd, "arrayctor.done");
  llvm::BasicBlock *contBB = createBasicBlock("arrayctor.cont");
  Builder.CreateCondBr(done, contBB, loopBB);

  // Patch the earlier check to skip over the loop.
  if (zeroCheckBranch) zeroCheckBranch->setSuccessor(0, contBB);

  EmitBlock(contBB);
}

void CodeGenFunction::destroyCXXObject(CodeGenFunction &CGF,
                                       llvm::Value *addr,
                                       QualType type) {
  const RecordType *rtype = type->castAs<RecordType>();
  const CXXRecordDecl *record = cast<CXXRecordDecl>(rtype->getDecl());
  const CXXDestructorDecl *dtor = record->getDestructor();
  assert(!dtor->isTrivial());
  CGF.EmitCXXDestructorCall(dtor, Dtor_Complete, /*for vbase*/ false,
                            addr);
}

void
CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
                                        CXXCtorType Type, bool ForVirtualBase,
                                        llvm::Value *This,
                                        CallExpr::const_arg_iterator ArgBeg,
                                        CallExpr::const_arg_iterator ArgEnd) {

  CGDebugInfo *DI = getDebugInfo();
  if (DI && CGM.getCodeGenOpts().LimitDebugInfo) {
    // If debug info for this class has not been emitted then this is the
    // right time to do so.
    const CXXRecordDecl *Parent = D->getParent();
    DI->getOrCreateRecordType(CGM.getContext().getTypeDeclType(Parent),
                              Parent->getLocation());
  }

  if (D->isTrivial()) {
    if (ArgBeg == ArgEnd) {
      // Trivial default constructor, no codegen required.
      assert(D->isDefaultConstructor() &&
             "trivial 0-arg ctor not a default ctor");
      return;
    }

    assert(ArgBeg + 1 == ArgEnd && "unexpected argcount for trivial ctor");
    assert(D->isCopyOrMoveConstructor() &&
           "trivial 1-arg ctor not a copy/move ctor");

    const Expr *E = (*ArgBeg);
    QualType Ty = E->getType();
    llvm::Value *Src = EmitLValue(E).getAddress();
    EmitAggregateCopy(This, Src, Ty);
    return;
  }

  llvm::Value *VTT = GetVTTParameter(*this, GlobalDecl(D, Type), ForVirtualBase);
  llvm::Value *Callee = CGM.GetAddrOfCXXConstructor(D, Type);

  EmitCXXMemberCall(D, Callee, ReturnValueSlot(), This, VTT, ArgBeg, ArgEnd);
}

void
CodeGenFunction::EmitSynthesizedCXXCopyCtorCall(const CXXConstructorDecl *D,
                                        llvm::Value *This, llvm::Value *Src,
                                        CallExpr::const_arg_iterator ArgBeg,
                                        CallExpr::const_arg_iterator ArgEnd) {
  if (D->isTrivial()) {
    assert(ArgBeg + 1 == ArgEnd && "unexpected argcount for trivial ctor");
    assert(D->isCopyOrMoveConstructor() &&
           "trivial 1-arg ctor not a copy/move ctor");
    EmitAggregateCopy(This, Src, (*ArgBeg)->getType());
    return;
  }
  llvm::Value *Callee = CGM.GetAddrOfCXXConstructor(D, 
                                                    clang::Ctor_Complete);
  assert(D->isInstance() &&
         "Trying to emit a member call expr on a static method!");
  
  const FunctionProtoType *FPT = D->getType()->getAs<FunctionProtoType>();
  
  CallArgList Args;
  
  // Push the this ptr.
  Args.add(RValue::get(This), D->getThisType(getContext()));
  
  
  // Push the src ptr.
  QualType QT = *(FPT->arg_type_begin());
  llvm::Type *t = CGM.getTypes().ConvertType(QT);
  Src = Builder.CreateBitCast(Src, t);
  Args.add(RValue::get(Src), QT);
  
  // Skip over first argument (Src).
  ++ArgBeg;
  CallExpr::const_arg_iterator Arg = ArgBeg;
  for (FunctionProtoType::arg_type_iterator I = FPT->arg_type_begin()+1,
       E = FPT->arg_type_end(); I != E; ++I, ++Arg) {
    assert(Arg != ArgEnd && "Running over edge of argument list!");
    EmitCallArg(Args, *Arg, *I);
  }
  // Either we've emitted all the call args, or we have a call to a
  // variadic function.
  assert((Arg == ArgEnd || FPT->isVariadic()) &&
         "Extra arguments in non-variadic function!");
  // If we still have any arguments, emit them using the type of the argument.
  for (; Arg != ArgEnd; ++Arg) {
    QualType ArgType = Arg->getType();
    EmitCallArg(Args, *Arg, ArgType);
  }
  
  EmitCall(CGM.getTypes().arrangeFunctionCall(Args, FPT), Callee,
           ReturnValueSlot(), Args, D);
}

void
CodeGenFunction::EmitDelegateCXXConstructorCall(const CXXConstructorDecl *Ctor,
                                                CXXCtorType CtorType,
                                                const FunctionArgList &Args) {
  CallArgList DelegateArgs;

  FunctionArgList::const_iterator I = Args.begin(), E = Args.end();
  assert(I != E && "no parameters to constructor");

  // this
  DelegateArgs.add(RValue::get(LoadCXXThis()), (*I)->getType());
  ++I;

  // vtt
  if (llvm::Value *VTT = GetVTTParameter(*this, GlobalDecl(Ctor, CtorType),
                                         /*ForVirtualBase=*/false)) {
    QualType VoidPP = getContext().getPointerType(getContext().VoidPtrTy);
    DelegateArgs.add(RValue::get(VTT), VoidPP);

    if (CodeGenVTables::needsVTTParameter(CurGD)) {
      assert(I != E && "cannot skip vtt parameter, already done with args");
      assert((*I)->getType() == VoidPP && "skipping parameter not of vtt type");
      ++I;
    }
  }

  // Explicit arguments.
  for (; I != E; ++I) {
    const VarDecl *param = *I;
    EmitDelegateCallArg(DelegateArgs, param);
  }

  EmitCall(CGM.getTypes().arrangeCXXConstructorDeclaration(Ctor, CtorType),
           CGM.GetAddrOfCXXConstructor(Ctor, CtorType), 
           ReturnValueSlot(), DelegateArgs, Ctor);
}

namespace {
  struct CallDelegatingCtorDtor : EHScopeStack::Cleanup {
    const CXXDestructorDecl *Dtor;
    llvm::Value *Addr;
    CXXDtorType Type;

    CallDelegatingCtorDtor(const CXXDestructorDecl *D, llvm::Value *Addr,
                           CXXDtorType Type)
      : Dtor(D), Addr(Addr), Type(Type) {}

    void Emit(CodeGenFunction &CGF, Flags flags) {
      CGF.EmitCXXDestructorCall(Dtor, Type, /*ForVirtualBase=*/false,
                                Addr);
    }
  };
}

void
CodeGenFunction::EmitDelegatingCXXConstructorCall(const CXXConstructorDecl *Ctor,
                                                  const FunctionArgList &Args) {
  assert(Ctor->isDelegatingConstructor());

  llvm::Value *ThisPtr = LoadCXXThis();

  QualType Ty = getContext().getTagDeclType(Ctor->getParent());
  CharUnits Alignment = getContext().getTypeAlignInChars(Ty);
  AggValueSlot AggSlot =
    AggValueSlot::forAddr(ThisPtr, Alignment, Qualifiers(),
                          AggValueSlot::IsDestructed,
                          AggValueSlot::DoesNotNeedGCBarriers,
                          AggValueSlot::IsNotAliased);

  EmitAggExpr(Ctor->init_begin()[0]->getInit(), AggSlot);

  const CXXRecordDecl *ClassDecl = Ctor->getParent();
  if (CGM.getLangOptions().Exceptions && !ClassDecl->hasTrivialDestructor()) {
    CXXDtorType Type =
      CurGD.getCtorType() == Ctor_Complete ? Dtor_Complete : Dtor_Base;

    EHStack.pushCleanup<CallDelegatingCtorDtor>(EHCleanup,
                                                ClassDecl->getDestructor(),
                                                ThisPtr, Type);
  }
}

void CodeGenFunction::EmitCXXDestructorCall(const CXXDestructorDecl *DD,
                                            CXXDtorType Type,
                                            bool ForVirtualBase,
                                            llvm::Value *This) {
  llvm::Value *VTT = GetVTTParameter(*this, GlobalDecl(DD, Type), 
                                     ForVirtualBase);
  llvm::Value *Callee = 0;
  if (getContext().getLangOptions().AppleKext)
    Callee = BuildAppleKextVirtualDestructorCall(DD, Type, 
                                                 DD->getParent());
    
  if (!Callee)
    Callee = CGM.GetAddrOfCXXDestructor(DD, Type);
  
  EmitCXXMemberCall(DD, Callee, ReturnValueSlot(), This, VTT, 0, 0);
}

namespace {
  struct CallLocalDtor : EHScopeStack::Cleanup {
    const CXXDestructorDecl *Dtor;
    llvm::Value *Addr;

    CallLocalDtor(const CXXDestructorDecl *D, llvm::Value *Addr)
      : Dtor(D), Addr(Addr) {}

    void Emit(CodeGenFunction &CGF, Flags flags) {
      CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
                                /*ForVirtualBase=*/false, Addr);
    }
  };
}

void CodeGenFunction::PushDestructorCleanup(const CXXDestructorDecl *D,
                                            llvm::Value *Addr) {
  EHStack.pushCleanup<CallLocalDtor>(NormalAndEHCleanup, D, Addr);
}

void CodeGenFunction::PushDestructorCleanup(QualType T, llvm::Value *Addr) {
  CXXRecordDecl *ClassDecl = T->getAsCXXRecordDecl();
  if (!ClassDecl) return;
  if (ClassDecl->hasTrivialDestructor()) return;

  const CXXDestructorDecl *D = ClassDecl->getDestructor();
  assert(D && D->isUsed() && "destructor not marked as used!");
  PushDestructorCleanup(D, Addr);
}

llvm::Value *
CodeGenFunction::GetVirtualBaseClassOffset(llvm::Value *This,
                                           const CXXRecordDecl *ClassDecl,
                                           const CXXRecordDecl *BaseClassDecl) {
  llvm::Value *VTablePtr = GetVTablePtr(This, Int8PtrTy);
  CharUnits VBaseOffsetOffset = 
    CGM.getVTableContext().getVirtualBaseOffsetOffset(ClassDecl, BaseClassDecl);
  
  llvm::Value *VBaseOffsetPtr = 
    Builder.CreateConstGEP1_64(VTablePtr, VBaseOffsetOffset.getQuantity(), 
                               "vbase.offset.ptr");
  llvm::Type *PtrDiffTy = 
    ConvertType(getContext().getPointerDiffType());
  
  VBaseOffsetPtr = Builder.CreateBitCast(VBaseOffsetPtr, 
                                         PtrDiffTy->getPointerTo());
                                         
  llvm::Value *VBaseOffset = Builder.CreateLoad(VBaseOffsetPtr, "vbase.offset");
  
  return VBaseOffset;
}

void
CodeGenFunction::InitializeVTablePointer(BaseSubobject Base, 
                                         const CXXRecordDecl *NearestVBase,
                                         CharUnits OffsetFromNearestVBase,
                                         llvm::Constant *VTable,
                                         const CXXRecordDecl *VTableClass) {
  const CXXRecordDecl *RD = Base.getBase();

  // Compute the address point.
  llvm::Value *VTableAddressPoint;

  // Check if we need to use a vtable from the VTT.
  if (CodeGenVTables::needsVTTParameter(CurGD) &&
      (RD->getNumVBases() || NearestVBase)) {
    // Get the secondary vpointer index.
    uint64_t VirtualPointerIndex = 
     CGM.getVTables().getSecondaryVirtualPointerIndex(VTableClass, Base);
    
    /// Load the VTT.
    llvm::Value *VTT = LoadCXXVTT();
    if (VirtualPointerIndex)
      VTT = Builder.CreateConstInBoundsGEP1_64(VTT, VirtualPointerIndex);

    // And load the address point from the VTT.
    VTableAddressPoint = Builder.CreateLoad(VTT);
  } else {
    uint64_t AddressPoint =
      CGM.getVTableContext().getVTableLayout(VTableClass).getAddressPoint(Base);
    VTableAddressPoint =
      Builder.CreateConstInBoundsGEP2_64(VTable, 0, AddressPoint);
  }

  // Compute where to store the address point.
  llvm::Value *VirtualOffset = 0;
  CharUnits NonVirtualOffset = CharUnits::Zero();
  
  if (CodeGenVTables::needsVTTParameter(CurGD) && NearestVBase) {
    // We need to use the virtual base offset offset because the virtual base
    // might have a different offset in the most derived class.
    VirtualOffset = GetVirtualBaseClassOffset(LoadCXXThis(), VTableClass, 
                                              NearestVBase);
    NonVirtualOffset = OffsetFromNearestVBase;
  } else {
    // We can just use the base offset in the complete class.
    NonVirtualOffset = Base.getBaseOffset();
  }
  
  // Apply the offsets.
  llvm::Value *VTableField = LoadCXXThis();
  
  if (!NonVirtualOffset.isZero() || VirtualOffset)
    VTableField = ApplyNonVirtualAndVirtualOffset(*this, VTableField, 
                                                  NonVirtualOffset,
                                                  VirtualOffset);

  // Finally, store the address point.
  llvm::Type *AddressPointPtrTy =
    VTableAddressPoint->getType()->getPointerTo();
  VTableField = Builder.CreateBitCast(VTableField, AddressPointPtrTy);
  Builder.CreateStore(VTableAddressPoint, VTableField);
}

void
CodeGenFunction::InitializeVTablePointers(BaseSubobject Base, 
                                          const CXXRecordDecl *NearestVBase,
                                          CharUnits OffsetFromNearestVBase,
                                          bool BaseIsNonVirtualPrimaryBase,
                                          llvm::Constant *VTable,
                                          const CXXRecordDecl *VTableClass,
                                          VisitedVirtualBasesSetTy& VBases) {
  // If this base is a non-virtual primary base the address point has already
  // been set.
  if (!BaseIsNonVirtualPrimaryBase) {
    // Initialize the vtable pointer for this base.
    InitializeVTablePointer(Base, NearestVBase, OffsetFromNearestVBase,
                            VTable, VTableClass);
  }
  
  const CXXRecordDecl *RD = Base.getBase();

  // Traverse bases.
  for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 
       E = RD->bases_end(); I != E; ++I) {
    CXXRecordDecl *BaseDecl
      = cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());

    // Ignore classes without a vtable.
    if (!BaseDecl->isDynamicClass())
      continue;

    CharUnits BaseOffset;
    CharUnits BaseOffsetFromNearestVBase;
    bool BaseDeclIsNonVirtualPrimaryBase;

    if (I->isVirtual()) {
      // Check if we've visited this virtual base before.
      if (!VBases.insert(BaseDecl))
        continue;

      const ASTRecordLayout &Layout = 
        getContext().getASTRecordLayout(VTableClass);

      BaseOffset = Layout.getVBaseClassOffset(BaseDecl);
      BaseOffsetFromNearestVBase = CharUnits::Zero();
      BaseDeclIsNonVirtualPrimaryBase = false;
    } else {
      const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);

      BaseOffset = Base.getBaseOffset() + Layout.getBaseClassOffset(BaseDecl);
      BaseOffsetFromNearestVBase = 
        OffsetFromNearestVBase + Layout.getBaseClassOffset(BaseDecl);
      BaseDeclIsNonVirtualPrimaryBase = Layout.getPrimaryBase() == BaseDecl;
    }
    
    InitializeVTablePointers(BaseSubobject(BaseDecl, BaseOffset), 
                             I->isVirtual() ? BaseDecl : NearestVBase,
                             BaseOffsetFromNearestVBase,
                             BaseDeclIsNonVirtualPrimaryBase, 
                             VTable, VTableClass, VBases);
  }
}

void CodeGenFunction::InitializeVTablePointers(const CXXRecordDecl *RD) {
  // Ignore classes without a vtable.
  if (!RD->isDynamicClass())
    return;

  // Get the VTable.
  llvm::Constant *VTable = CGM.getVTables().GetAddrOfVTable(RD);

  // Initialize the vtable pointers for this class and all of its bases.
  VisitedVirtualBasesSetTy VBases;
  InitializeVTablePointers(BaseSubobject(RD, CharUnits::Zero()), 
                           /*NearestVBase=*/0, 
                           /*OffsetFromNearestVBase=*/CharUnits::Zero(),
                           /*BaseIsNonVirtualPrimaryBase=*/false, 
                           VTable, RD, VBases);
}

llvm::Value *CodeGenFunction::GetVTablePtr(llvm::Value *This,
                                           llvm::Type *Ty) {
  llvm::Value *VTablePtrSrc = Builder.CreateBitCast(This, Ty->getPointerTo());
  return Builder.CreateLoad(VTablePtrSrc, "vtable");
}

static const CXXRecordDecl *getMostDerivedClassDecl(const Expr *Base) {
  const Expr *E = Base;
  
  while (true) {
    E = E->IgnoreParens();
    if (const CastExpr *CE = dyn_cast<CastExpr>(E)) {
      if (CE->getCastKind() == CK_DerivedToBase || 
          CE->getCastKind() == CK_UncheckedDerivedToBase ||
          CE->getCastKind() == CK_NoOp) {
        E = CE->getSubExpr();
        continue;
      }
    }

    break;
  }

  QualType DerivedType = E->getType();
  if (const PointerType *PTy = DerivedType->getAs<PointerType>())
    DerivedType = PTy->getPointeeType();

  return cast<CXXRecordDecl>(DerivedType->castAs<RecordType>()->getDecl());
}

// FIXME: Ideally Expr::IgnoreParenNoopCasts should do this, but it doesn't do
// quite what we want.
static const Expr *skipNoOpCastsAndParens(const Expr *E) {
  while (true) {
    if (const ParenExpr *PE = dyn_cast<ParenExpr>(E)) {
      E = PE->getSubExpr();
      continue;
    }

    if (const CastExpr *CE = dyn_cast<CastExpr>(E)) {
      if (CE->getCastKind() == CK_NoOp) {
        E = CE->getSubExpr();
        continue;
      }
    }
    if (const UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
      if (UO->getOpcode() == UO_Extension) {
        E = UO->getSubExpr();
        continue;
      }
    }
    return E;
  }
}

/// canDevirtualizeMemberFunctionCall - Checks whether the given virtual member
/// function call on the given expr can be devirtualized.
static bool canDevirtualizeMemberFunctionCall(const Expr *Base, 
                                              const CXXMethodDecl *MD) {
  // If the most derived class is marked final, we know that no subclass can
  // override this member function and so we can devirtualize it. For example:
  //
  // struct A { virtual void f(); }
  // struct B final : A { };
  //
  // void f(B *b) {
  //   b->f();
  // }
  //
  const CXXRecordDecl *MostDerivedClassDecl = getMostDerivedClassDecl(Base);
  if (MostDerivedClassDecl->hasAttr<FinalAttr>())
    return true;

  // If the member function is marked 'final', we know that it can't be
  // overridden and can therefore devirtualize it.
  if (MD->hasAttr<FinalAttr>())
    return true;

  // Similarly, if the class itself is marked 'final' it can't be overridden
  // and we can therefore devirtualize the member function call.
  if (MD->getParent()->hasAttr<FinalAttr>())
    return true;

  Base = skipNoOpCastsAndParens(Base);
  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Base)) {
    if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
      // This is a record decl. We know the type and can devirtualize it.
      return VD->getType()->isRecordType();
    }
    
    return false;
  }
  
  // We can always devirtualize calls on temporary object expressions.
  if (isa<CXXConstructExpr>(Base))
    return true;
  
  // And calls on bound temporaries.
  if (isa<CXXBindTemporaryExpr>(Base))
    return true;
  
  // Check if this is a call expr that returns a record type.
  if (const CallExpr *CE = dyn_cast<CallExpr>(Base))
    return CE->getCallReturnType()->isRecordType();

  // We can't devirtualize the call.
  return false;
}

static bool UseVirtualCall(ASTContext &Context,
                           const CXXOperatorCallExpr *CE,
                           const CXXMethodDecl *MD) {
  if (!MD->isVirtual())
    return false;
  
  // When building with -fapple-kext, all calls must go through the vtable since
  // the kernel linker can do runtime patching of vtables.
  if (Context.getLangOptions().AppleKext)
    return true;

  return !canDevirtualizeMemberFunctionCall(CE->getArg(0), MD);
}

llvm::Value *
CodeGenFunction::EmitCXXOperatorMemberCallee(const CXXOperatorCallExpr *E,
                                             const CXXMethodDecl *MD,
                                             llvm::Value *This) {
  llvm::FunctionType *fnType =
    CGM.getTypes().GetFunctionType(
                             CGM.getTypes().arrangeCXXMethodDeclaration(MD));

  if (UseVirtualCall(getContext(), E, MD))
    return BuildVirtualCall(MD, This, fnType);

  return CGM.GetAddrOfFunction(MD, fnType);
}

void CodeGenFunction::EmitLambdaToBlockPointerBody(FunctionArgList &Args) {
  CGM.ErrorUnsupported(CurFuncDecl, "lambda conversion to block");
}

void CodeGenFunction::EmitLambdaDelegatingInvokeBody(const CXXMethodDecl *MD) {
  const CXXRecordDecl *Lambda = MD->getParent();
  DeclarationName Name
    = getContext().DeclarationNames.getCXXOperatorName(OO_Call);
  DeclContext::lookup_const_result Calls = Lambda->lookup(Name);
  CXXMethodDecl *CallOperator = cast<CXXMethodDecl>(*Calls.first++);
  const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
  QualType ResultType = FPT->getResultType();

  // Start building arguments for forwarding call
  CallArgList CallArgs;

  QualType ThisType = getContext().getPointerType(getContext().getRecordType(Lambda));
  llvm::Value *ThisPtr = llvm::UndefValue::get(getTypes().ConvertType(ThisType));
  CallArgs.add(RValue::get(ThisPtr), ThisType);

  // Add the rest of the parameters.
  for (FunctionDecl::param_const_iterator I = MD->param_begin(),
       E = MD->param_end(); I != E; ++I) {
    ParmVarDecl *param = *I;
    EmitDelegateCallArg(CallArgs, param);
  }

  // Get the address of the call operator.
  GlobalDecl GD(CallOperator);
  const CGFunctionInfo &CalleeFnInfo =
    CGM.getTypes().arrangeFunctionCall(ResultType, CallArgs, FPT->getExtInfo(),
                                       RequiredArgs::forPrototypePlus(FPT, 1));
  llvm::Type *Ty = CGM.getTypes().GetFunctionType(CalleeFnInfo);
  llvm::Value *Callee = CGM.GetAddrOfFunction(GD, Ty);

  // Determine whether we have a return value slot to use.
  ReturnValueSlot Slot;
  if (!ResultType->isVoidType() &&
      CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect &&
      hasAggregateLLVMType(CurFnInfo->getReturnType()))
    Slot = ReturnValueSlot(ReturnValue, ResultType.isVolatileQualified());
  
  // Now emit our call.
  RValue RV = EmitCall(CalleeFnInfo, Callee, Slot, CallArgs, CallOperator);

  // Forward the returned value
  if (!ResultType->isVoidType() && Slot.isNull())
    EmitReturnOfRValue(RV, ResultType);
}

void CodeGenFunction::EmitLambdaStaticInvokeFunction(const CXXMethodDecl *MD) {
  if (MD->isVariadic()) {
    // FIXME: Making this work correctly is nasty because it requires either
    // cloning the body of the call operator or making the call operator forward.
    CGM.ErrorUnsupported(MD, "lambda conversion to variadic function");
  }

  EmitLambdaDelegatingInvokeBody(MD);
}