CGClass.cpp

  // otherwise, go to the block after the for-loop.
  llvm::Value *Counter = Builder.CreateLoad(IndexPtr);
  llvm::Value *IsLess = Builder.CreateICmpULT(Counter, NumElements, "isless");
  // If the condition is true, execute the body.
  Builder.CreateCondBr(IsLess, ForBody, AfterFor);

  EmitBlock(ForBody);

  llvm::BasicBlock *ContinueBlock = createBasicBlock("for.inc");
  // Inside the loop body, emit the constructor call on the array element.
  Counter = Builder.CreateLoad(IndexPtr);
  llvm::Value *Address = Builder.CreateInBoundsGEP(ArrayPtr, Counter, 
                                                   "arrayidx");

  // Zero initialize the storage, if requested.
  if (ZeroInitialization)
    EmitNullInitialization(Address, 
                           getContext().getTypeDeclType(D->getParent()));
  
  // 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.
  
  // Keep track of the current number of live temporaries.
  {
    RunCleanupsScope Scope(*this);

    EmitCXXConstructorCall(D, Ctor_Complete, /*ForVirtualBase=*/false, Address,
                           ArgBeg, ArgEnd);
  }

  EmitBlock(ContinueBlock);

  // Emit the increment of the loop counter.
  llvm::Value *NextVal = llvm::ConstantInt::get(SizeTy, 1);
  Counter = Builder.CreateLoad(IndexPtr);
  NextVal = Builder.CreateAdd(Counter, NextVal, "inc");
  Builder.CreateStore(NextVal, IndexPtr);

  // Finally, branch back up to the condition for the next iteration.
  EmitBranch(CondBlock);

  // Emit the fall-through block.
  EmitBlock(AfterFor, true);
}

/// EmitCXXAggrDestructorCall - calls the default destructor on array
/// elements in reverse order of construction.
void
CodeGenFunction::EmitCXXAggrDestructorCall(const CXXDestructorDecl *D,
                                           const ArrayType *Array,
                                           llvm::Value *This) {
  const ConstantArrayType *CA = dyn_cast<ConstantArrayType>(Array);
  assert(CA && "Do we support VLA for destruction ?");
  uint64_t ElementCount = getContext().getConstantArrayElementCount(CA);
  
  const llvm::Type *SizeLTy = ConvertType(getContext().getSizeType());
  llvm::Value* ElementCountPtr = llvm::ConstantInt::get(SizeLTy, ElementCount);
  EmitCXXAggrDestructorCall(D, ElementCountPtr, This);
}

/// EmitCXXAggrDestructorCall - calls the default destructor on array
/// elements in reverse order of construction.
void
CodeGenFunction::EmitCXXAggrDestructorCall(const CXXDestructorDecl *D,
                                           llvm::Value *UpperCount,
                                           llvm::Value *This) {
  const llvm::Type *SizeLTy = ConvertType(getContext().getSizeType());
  llvm::Value *One = llvm::ConstantInt::get(SizeLTy, 1);
  
  // Create a temporary for the loop index and initialize it with count of
  // array elements.
  llvm::Value *IndexPtr = CreateTempAlloca(SizeLTy, "loop.index");

  // Store the number of elements in the index pointer.
  Builder.CreateStore(UpperCount, IndexPtr);

  // Start the loop with a block that tests the condition.
  llvm::BasicBlock *CondBlock = createBasicBlock("for.cond");
  llvm::BasicBlock *AfterFor = createBasicBlock("for.end");

  EmitBlock(CondBlock);

  llvm::BasicBlock *ForBody = createBasicBlock("for.body");

  // Generate: if (loop-index != 0 fall to the loop body,
  // otherwise, go to the block after the for-loop.
  llvm::Value* zeroConstant =
    llvm::Constant::getNullValue(SizeLTy);
  llvm::Value *Counter = Builder.CreateLoad(IndexPtr);
  llvm::Value *IsNE = Builder.CreateICmpNE(Counter, zeroConstant,
                                            "isne");
  // If the condition is true, execute the body.
  Builder.CreateCondBr(IsNE, ForBody, AfterFor);

  EmitBlock(ForBody);

  llvm::BasicBlock *ContinueBlock = createBasicBlock("for.inc");
  // Inside the loop body, emit the constructor call on the array element.
  Counter = Builder.CreateLoad(IndexPtr);
  Counter = Builder.CreateSub(Counter, One);
  llvm::Value *Address = Builder.CreateInBoundsGEP(This, Counter, "arrayidx");
  EmitCXXDestructorCall(D, Dtor_Complete, /*ForVirtualBase=*/false, Address);

  EmitBlock(ContinueBlock);

  // Emit the decrement of the loop counter.
  Counter = Builder.CreateLoad(IndexPtr);
  Counter = Builder.CreateSub(Counter, One, "dec");
  Builder.CreateStore(Counter, IndexPtr);

  // Finally, branch back up to the condition for the next iteration.
  EmitBranch(CondBlock);

  // Emit the fall-through block.
  EmitBlock(AfterFor, true);
}

void
CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
                                        CXXCtorType Type, bool ForVirtualBase,
                                        llvm::Value *This,
                                        CallExpr::const_arg_iterator ArgBeg,
                                        CallExpr::const_arg_iterator ArgEnd) {
  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->isCopyConstructor() && "trivial 1-arg ctor not a copy 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->isCopyConstructor() && "trivial 1-arg ctor not a copy 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.push_back(std::make_pair(RValue::get(This),
                                D->getThisType(getContext())));
  
  
  // Push the src ptr.
  QualType QT = *(FPT->arg_type_begin());
  const llvm::Type *t = CGM.getTypes().ConvertType(QT);
  Src = Builder.CreateBitCast(Src, t);
  Args.push_back(std::make_pair(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!");
    QualType ArgType = *I;
    Args.push_back(std::make_pair(EmitCallArg(*Arg, ArgType),
                                  ArgType));
  }
  // 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();
    Args.push_back(std::make_pair(EmitCallArg(*Arg, ArgType),
                                  ArgType));
  }
  
  QualType ResultType = FPT->getResultType();
  EmitCall(CGM.getTypes().getFunctionInfo(ResultType, Args,
                                          FPT->getExtInfo()),
                  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.push_back(std::make_pair(RValue::get(LoadCXXThis()),
                                        I->second));
  ++I;

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

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

  // Explicit arguments.
  for (; I != E; ++I) {
    const VarDecl *Param = I->first;
    QualType ArgType = Param->getType(); // because we're passing it to itself
    RValue Arg = EmitDelegateCallArg(Param);

    DelegateArgs.push_back(std::make_pair(Arg, ArgType));
  }

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

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 = 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, bool IsForEH) {
      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();
  PushDestructorCleanup(D, Addr);
}

llvm::Value *
CodeGenFunction::GetVirtualBaseClassOffset(llvm::Value *This,
                                           const CXXRecordDecl *ClassDecl,
                                           const CXXRecordDecl *BaseClassDecl) {
  const llvm::Type *Int8PtrTy = 
    llvm::Type::getInt8Ty(VMContext)->getPointerTo();

  llvm::Value *VTablePtr = GetVTablePtr(This, Int8PtrTy);
  int64_t VBaseOffsetOffset = 
    CGM.getVTables().getVirtualBaseOffsetOffset(ClassDecl, BaseClassDecl);
  
  llvm::Value *VBaseOffsetPtr = 
    Builder.CreateConstGEP1_64(VTablePtr, VBaseOffsetOffset, "vbase.offset.ptr");
  const 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,
                                         uint64_t 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.getVTables().getAddressPoint(Base, VTableClass);
    VTableAddressPoint =
      Builder.CreateConstInBoundsGEP2_64(VTable, 0, AddressPoint);
  }

  // Compute where to store the address point.
  llvm::Value *VirtualOffset = 0;
  uint64_t NonVirtualOffset = 0;
  
  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 / 8;
  } else {
    // We can just use the base offset in the complete class.
    NonVirtualOffset = Base.getBaseOffset() / 8;
  }
  
  // Apply the offsets.
  llvm::Value *VTableField = LoadCXXThis();
  
  if (NonVirtualOffset || VirtualOffset)
    VTableField = ApplyNonVirtualAndVirtualOffset(*this, VTableField, 
                                                  NonVirtualOffset,
                                                  VirtualOffset);

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

void
CodeGenFunction::InitializeVTablePointers(BaseSubobject Base, 
                                          const CXXRecordDecl *NearestVBase,
                                          uint64_t 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;

    uint64_t BaseOffset;
    uint64_t 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.getVBaseClassOffsetInBits(BaseDecl);
      BaseOffsetFromNearestVBase = 0;
      BaseDeclIsNonVirtualPrimaryBase = false;
    } else {
      const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);

      BaseOffset = 
        Base.getBaseOffset() + Layout.getBaseClassOffsetInBits(BaseDecl);
      BaseOffsetFromNearestVBase = 
        OffsetFromNearestVBase + Layout.getBaseClassOffsetInBits(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, 0), /*NearestVBase=*/0, 
                           /*OffsetFromNearestVBase=*/0,
                           /*BaseIsNonVirtualPrimaryBase=*/false, 
                           VTable, RD, VBases);
}

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