//===--- CGClass.cpp - Emit LLVM Code for C++ classes ---------------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This contains code dealing with C++ code generation of classes // //===----------------------------------------------------------------------===// #include "CGBlocks.h" #include "CGDebugInfo.h" #include "CodeGenFunction.h" #include "clang/AST/CXXInheritance.h" #include "clang/AST/EvaluatedExprVisitor.h" #include "clang/AST/RecordLayout.h" #include "clang/AST/StmtCXX.h" #include "clang/Frontend/CodeGenOptions.h" using namespace clang; using namespace CodeGen; static CharUnits ComputeNonVirtualBaseClassOffset(ASTContext &Context, const CXXRecordDecl *DerivedClass, CastExpr::path_const_iterator Start, CastExpr::path_const_iterator End) { CharUnits Offset = CharUnits::Zero(); const CXXRecordDecl *RD = DerivedClass; for (CastExpr::path_const_iterator I = Start; I != End; ++I) { const CXXBaseSpecifier *Base = *I; assert(!Base->isVirtual() && "Should not see virtual bases here!"); // Get the layout. const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); const CXXRecordDecl *BaseDecl = cast<CXXRecordDecl>(Base->getType()->getAs<RecordType>()->getDecl()); // Add the offset. Offset += Layout.getBaseClassOffset(BaseDecl); RD = BaseDecl; } return Offset; } llvm::Constant * CodeGenModule::GetNonVirtualBaseClassOffset(const CXXRecordDecl *ClassDecl, CastExpr::path_const_iterator PathBegin, CastExpr::path_const_iterator PathEnd) { assert(PathBegin != PathEnd && "Base path should not be empty!"); CharUnits Offset = ComputeNonVirtualBaseClassOffset(getContext(), ClassDecl, PathBegin, PathEnd); if (Offset.isZero()) return 0; llvm::Type *PtrDiffTy = Types.ConvertType(getContext().getPointerDiffType()); return llvm::ConstantInt::get(PtrDiffTy, Offset.getQuantity()); } /// Gets the address of a direct base class within a complete object. /// This should only be used for (1) non-virtual bases or (2) virtual bases /// when the type is known to be complete (e.g. in complete destructors). /// /// The object pointed to by 'This' is assumed to be non-null. llvm::Value * CodeGenFunction::GetAddressOfDirectBaseInCompleteClass(llvm::Value *This, const CXXRecordDecl *Derived, const CXXRecordDecl *Base, bool BaseIsVirtual) { // 'this' must be a pointer (in some address space) to Derived. assert(This->getType()->isPointerTy() && cast<llvm::PointerType>(This->getType())->getElementType() == ConvertType(Derived)); // Compute the offset of the virtual base. CharUnits Offset; const ASTRecordLayout &Layout = getContext().getASTRecordLayout(Derived); if (BaseIsVirtual) Offset = Layout.getVBaseClassOffset(Base); else Offset = Layout.getBaseClassOffset(Base); // Shift and cast down to the base type. // TODO: for complete types, this should be possible with a GEP. llvm::Value *V = This; if (Offset.isPositive()) { V = Builder.CreateBitCast(V, Int8PtrTy); V = Builder.CreateConstInBoundsGEP1_64(V, Offset.getQuantity()); } V = Builder.CreateBitCast(V, ConvertType(Base)->getPointerTo()); return V; } static llvm::Value * ApplyNonVirtualAndVirtualOffset(CodeGenFunction &CGF, llvm::Value *ptr, CharUnits nonVirtualOffset, llvm::Value *virtualOffset) { // Assert that we have something to do. assert(!nonVirtualOffset.isZero() || virtualOffset != 0); // Compute the offset from the static and dynamic components. llvm::Value *baseOffset; if (!nonVirtualOffset.isZero()) { baseOffset = llvm::ConstantInt::get(CGF.PtrDiffTy, nonVirtualOffset.getQuantity()); if (virtualOffset) { baseOffset = CGF.Builder.CreateAdd(virtualOffset, baseOffset); } } else { baseOffset = virtualOffset; } // Apply the base offset. ptr = CGF.Builder.CreateBitCast(ptr, CGF.Int8PtrTy); ptr = CGF.Builder.CreateInBoundsGEP(ptr, baseOffset, "add.ptr"); return ptr; } llvm::Value * CodeGenFunction::GetAddressOfBaseClass(llvm::Value *Value, const CXXRecordDecl *Derived, CastExpr::path_const_iterator PathBegin, CastExpr::path_const_iterator PathEnd, bool NullCheckValue) { assert(PathBegin != PathEnd && "Base path should not be empty!"); CastExpr::path_const_iterator Start = PathBegin; const CXXRecordDecl *VBase = 0; // Sema has done some convenient canonicalization here: if the // access path involved any virtual steps, the conversion path will // *start* with a step down to the correct virtual base subobject, // and hence will not require any further steps. if ((*Start)->isVirtual()) { VBase = cast<CXXRecordDecl>((*Start)->getType()->getAs<RecordType>()->getDecl()); ++Start; } // Compute the static offset of the ultimate destination within its // allocating subobject (the virtual base, if there is one, or else // the "complete" object that we see). CharUnits NonVirtualOffset = ComputeNonVirtualBaseClassOffset(getContext(), VBase ? VBase : Derived, Start, PathEnd); // If there's a virtual step, we can sometimes "devirtualize" it. // For now, that's limited to when the derived type is final. // TODO: "devirtualize" this for accesses to known-complete objects. if (VBase && Derived->hasAttr<FinalAttr>()) { const ASTRecordLayout &layout = getContext().getASTRecordLayout(Derived); CharUnits vBaseOffset = layout.getVBaseClassOffset(VBase); NonVirtualOffset += vBaseOffset; VBase = 0; // we no longer have a virtual step } // Get the base pointer type. llvm::Type *BasePtrTy = ConvertType((PathEnd[-1])->getType())->getPointerTo(); // If the static offset is zero and we don't have a virtual step, // just do a bitcast; null checks are unnecessary. if (NonVirtualOffset.isZero() && !VBase) { return Builder.CreateBitCast(Value, BasePtrTy); } llvm::BasicBlock *origBB = 0; llvm::BasicBlock *endBB = 0; // Skip over the offset (and the vtable load) if we're supposed to // null-check the pointer. if (NullCheckValue) { origBB = Builder.GetInsertBlock(); llvm::BasicBlock *notNullBB = createBasicBlock("cast.notnull"); endBB = createBasicBlock("cast.end"); llvm::Value *isNull = Builder.CreateIsNull(Value); Builder.CreateCondBr(isNull, endBB, notNullBB); EmitBlock(notNullBB); } // Compute the virtual offset. llvm::Value *VirtualOffset = 0; if (VBase) { VirtualOffset = GetVirtualBaseClassOffset(Value, Derived, VBase); } // Apply both offsets. Value = ApplyNonVirtualAndVirtualOffset(*this, Value, NonVirtualOffset, VirtualOffset); // Cast to the destination type. Value = Builder.CreateBitCast(Value, BasePtrTy); // Build a phi if we needed a null check. if (NullCheckValue) { llvm::BasicBlock *notNullBB = Builder.GetInsertBlock(); Builder.CreateBr(endBB); EmitBlock(endBB); llvm::PHINode *PHI = Builder.CreatePHI(BasePtrTy, 2, "cast.result"); PHI->addIncoming(Value, notNullBB); PHI->addIncoming(llvm::Constant::getNullValue(BasePtrTy), origBB); Value = PHI; } return Value; } llvm::Value * CodeGenFunction::GetAddressOfDerivedClass(llvm::Value *Value, const CXXRecordDecl *Derived, CastExpr::path_const_iterator PathBegin, CastExpr::path_const_iterator PathEnd, bool NullCheckValue) { assert(PathBegin != PathEnd && "Base path should not be empty!"); QualType DerivedTy = getContext().getCanonicalType(getContext().getTagDeclType(Derived)); llvm::Type *DerivedPtrTy = ConvertType(DerivedTy)->getPointerTo(); llvm::Value *NonVirtualOffset = CGM.GetNonVirtualBaseClassOffset(Derived, PathBegin, PathEnd); if (!NonVirtualOffset) { // No offset, we can just cast back. return Builder.CreateBitCast(Value, DerivedPtrTy); } llvm::BasicBlock *CastNull = 0; llvm::BasicBlock *CastNotNull = 0; llvm::BasicBlock *CastEnd = 0; if (NullCheckValue) { CastNull = createBasicBlock("cast.null"); CastNotNull = createBasicBlock("cast.notnull"); CastEnd = createBasicBlock("cast.end"); llvm::Value *IsNull = Builder.CreateIsNull(Value); Builder.CreateCondBr(IsNull, CastNull, CastNotNull); EmitBlock(CastNotNull); } // Apply the offset. Value = Builder.CreateBitCast(Value, Int8PtrTy); Value = Builder.CreateGEP(Value, Builder.CreateNeg(NonVirtualOffset), "sub.ptr"); // Just cast. Value = Builder.CreateBitCast(Value, DerivedPtrTy); if (NullCheckValue) { Builder.CreateBr(CastEnd); EmitBlock(CastNull); Builder.CreateBr(CastEnd); EmitBlock(CastEnd); llvm::PHINode *PHI = Builder.CreatePHI(Value->getType(), 2); PHI->addIncoming(Value, CastNotNull); PHI->addIncoming(llvm::Constant::getNullValue(Value->getType()), CastNull); Value = PHI; } return Value; } /// GetVTTParameter - Return the VTT parameter that should be passed to a /// base constructor/destructor with virtual bases. static llvm::Value *GetVTTParameter(CodeGenFunction &CGF, GlobalDecl GD, bool ForVirtualBase) { if (!CodeGenVTables::needsVTTParameter(GD)) { // This constructor/destructor does not need a VTT parameter. return 0; } const CXXRecordDecl *RD = cast<CXXMethodDecl>(CGF.CurFuncDecl)->getParent(); const CXXRecordDecl *Base = cast<CXXMethodDecl>(GD.getDecl())->getParent(); llvm::Value *VTT; uint64_t SubVTTIndex; // If the record matches the base, this is the complete ctor/dtor // variant calling the base variant in a class with virtual bases. if (RD == Base) { assert(!CodeGenVTables::needsVTTParameter(CGF.CurGD) && "doing no-op VTT offset in base dtor/ctor?"); assert(!ForVirtualBase && "Can't have same class as virtual base!"); SubVTTIndex = 0; } else { const ASTRecordLayout &Layout = CGF.getContext().getASTRecordLayout(RD); CharUnits BaseOffset = ForVirtualBase ? Layout.getVBaseClassOffset(Base) : Layout.getBaseClassOffset(Base); SubVTTIndex = CGF.CGM.getVTables().getSubVTTIndex(RD, BaseSubobject(Base, BaseOffset)); assert(SubVTTIndex != 0 && "Sub-VTT index must be greater than zero!"); } if (CodeGenVTables::needsVTTParameter(CGF.CurGD)) { // A VTT parameter was passed to the constructor, use it. VTT = CGF.LoadCXXVTT(); VTT = CGF.Builder.CreateConstInBoundsGEP1_64(VTT, SubVTTIndex); } else { // We're the complete constructor, so get the VTT by name. VTT = CGF.CGM.getVTables().GetAddrOfVTT(RD); VTT = CGF.Builder.CreateConstInBoundsGEP2_64(VTT, 0, SubVTTIndex); } return VTT; } namespace { /// Call the destructor for a direct base class. struct CallBaseDtor : EHScopeStack::Cleanup { const CXXRecordDecl *BaseClass; bool BaseIsVirtual; CallBaseDtor(const CXXRecordDecl *Base, bool BaseIsVirtual) : BaseClass(Base), BaseIsVirtual(BaseIsVirtual) {} void Emit(CodeGenFunction &CGF, Flags flags) { const CXXRecordDecl *DerivedClass = cast<CXXMethodDecl>(CGF.CurCodeDecl)->getParent(); const CXXDestructorDecl *D = BaseClass->getDestructor(); llvm::Value *Addr = CGF.GetAddressOfDirectBaseInCompleteClass(CGF.LoadCXXThis(), DerivedClass, BaseClass, BaseIsVirtual); CGF.EmitCXXDestructorCall(D, Dtor_Base, BaseIsVirtual, Addr); } }; /// A visitor which checks whether an initializer uses 'this' in a /// way which requires the vtable to be properly set. struct DynamicThisUseChecker : EvaluatedExprVisitor<DynamicThisUseChecker> { typedef EvaluatedExprVisitor<DynamicThisUseChecker> super; bool UsesThis; DynamicThisUseChecker(ASTContext &C) : super(C), UsesThis(false) {} // Black-list all explicit and implicit references to 'this'. // // Do we need to worry about external references to 'this' derived // from arbitrary code? If so, then anything which runs arbitrary // external code might potentially access the vtable. void VisitCXXThisExpr(CXXThisExpr *E) { UsesThis = true; } }; } static bool BaseInitializerUsesThis(ASTContext &C, const Expr *Init) { DynamicThisUseChecker Checker(C); Checker.Visit(const_cast<Expr*>(Init)); return Checker.UsesThis; } static void EmitBaseInitializer(CodeGenFunction &CGF, const CXXRecordDecl *ClassDecl, CXXCtorInitializer *BaseInit, CXXCtorType CtorType) { assert(BaseInit->isBaseInitializer() && "Must have base initializer!"); llvm::Value *ThisPtr = CGF.LoadCXXThis(); const Type *BaseType = BaseInit->getBaseClass(); CXXRecordDecl *BaseClassDecl = cast<CXXRecordDecl>(BaseType->getAs<RecordType>()->getDecl()); bool isBaseVirtual = BaseInit->isBaseVirtual(); // The base constructor doesn't construct virtual bases. if (CtorType == Ctor_Base && isBaseVirtual) return; // If the initializer for the base (other than the constructor // itself) accesses 'this' in any way, we need to initialize the // vtables. if (BaseInitializerUsesThis(CGF.getContext(), BaseInit->getInit())) CGF.InitializeVTablePointers(ClassDecl); // We can pretend to be a complete class because it only matters for // virtual bases, and we only do virtual bases for complete ctors. llvm::Value *V = CGF.GetAddressOfDirectBaseInCompleteClass(ThisPtr, ClassDecl, BaseClassDecl, isBaseVirtual); CharUnits Alignment = CGF.getContext().getTypeAlignInChars(BaseType); AggValueSlot AggSlot = AggValueSlot::forAddr(V, Alignment, Qualifiers(), AggValueSlot::IsDestructed, AggValueSlot::DoesNotNeedGCBarriers, AggValueSlot::IsNotAliased); CGF.EmitAggExpr(BaseInit->getInit(), AggSlot); if (CGF.CGM.getLangOpts().Exceptions && !BaseClassDecl->hasTrivialDestructor()) CGF.EHStack.pushCleanup<CallBaseDtor>(EHCleanup, BaseClassDecl, isBaseVirtual); } static void EmitAggMemberInitializer(CodeGenFunction &CGF, LValue LHS, Expr *Init, llvm::Value *ArrayIndexVar, QualType T, ArrayRef<VarDecl *> ArrayIndexes, unsigned Index) { if (Index == ArrayIndexes.size()) { LValue LV = LHS; { // Scope for Cleanups. CodeGenFunction::RunCleanupsScope Cleanups(CGF); if (ArrayIndexVar) { // If we have an array index variable, load it and use it as an offset. // Then, increment the value. llvm::Value *Dest = LHS.getAddress(); llvm::Value *ArrayIndex = CGF.Builder.CreateLoad(ArrayIndexVar); Dest = CGF.Builder.CreateInBoundsGEP(Dest, ArrayIndex, "destaddress"); llvm::Value *Next = llvm::ConstantInt::get(ArrayIndex->getType(), 1); Next = CGF.Builder.CreateAdd(ArrayIndex, Next, "inc"); CGF.Builder.CreateStore(Next, ArrayIndexVar); // Update the LValue. LV.setAddress(Dest); CharUnits Align = CGF.getContext().getTypeAlignInChars(T); LV.setAlignment(std::min(Align, LV.getAlignment())); } if (!CGF.hasAggregateLLVMType(T)) { CGF.EmitScalarInit(Init, /*decl*/ 0, LV, false); } else if (T->isAnyComplexType()) { CGF.EmitComplexExprIntoAddr(Init, LV.getAddress(), LV.isVolatileQualified()); } else { AggValueSlot Slot = AggValueSlot::forLValue(LV, AggValueSlot::IsDestructed, AggValueSlot::DoesNotNeedGCBarriers, AggValueSlot::IsNotAliased); CGF.EmitAggExpr(Init, Slot); } } // Now, outside of the initializer cleanup scope, destroy the backing array // for a std::initializer_list member. CGF.MaybeEmitStdInitializerListCleanup(LV.getAddress(), Init); return; } const ConstantArrayType *Array = CGF.getContext().getAsConstantArrayType(T); assert(Array && "Array initialization without the array type?"); llvm::Value *IndexVar = CGF.GetAddrOfLocalVar(ArrayIndexes[Index]); assert(IndexVar && "Array index variable not loaded"); // Initialize this index variable to zero. llvm::Value* Zero = llvm::Constant::getNullValue( CGF.ConvertType(CGF.getContext().getSizeType())); CGF.Builder.CreateStore(Zero, IndexVar); // Start the loop with a block that tests the condition. llvm::BasicBlock *CondBlock = CGF.createBasicBlock("for.cond"); llvm::BasicBlock *AfterFor = CGF.createBasicBlock("for.end"); CGF.EmitBlock(CondBlock); llvm::BasicBlock *ForBody = CGF.createBasicBlock("for.body"); // Generate: if (loop-index < number-of-elements) fall to the loop body, // otherwise, go to the block after the for-loop. uint64_t NumElements = Array->getSize().getZExtValue(); llvm::Value *Counter = CGF.Builder.CreateLoad(IndexVar); llvm::Value *NumElementsPtr = llvm::ConstantInt::get(Counter->getType(), NumElements); llvm::Value *IsLess = CGF.Builder.CreateICmpULT(Counter, NumElementsPtr, "isless"); // If the condition is true, execute the body. CGF.Builder.CreateCondBr(IsLess, ForBody, AfterFor); CGF.EmitBlock(ForBody); llvm::BasicBlock *ContinueBlock = CGF.createBasicBlock("for.inc"); { CodeGenFunction::RunCleanupsScope Cleanups(CGF); // Inside the loop body recurse to emit the inner loop or, eventually, the // constructor call. EmitAggMemberInitializer(CGF, LHS, Init, ArrayIndexVar, Array->getElementType(), ArrayIndexes, Index + 1); } CGF.EmitBlock(ContinueBlock); // Emit the increment of the loop counter. llvm::Value *NextVal = llvm::ConstantInt::get(Counter->getType(), 1); Counter = CGF.Builder.CreateLoad(IndexVar); NextVal = CGF.Builder.CreateAdd(Counter, NextVal, "inc"); CGF.Builder.CreateStore(NextVal, IndexVar); // Finally, branch back up to the condition for the next iteration. CGF.EmitBranch(CondBlock); // Emit the fall-through block. CGF.EmitBlock(AfterFor, true); } namespace { struct CallMemberDtor : EHScopeStack::Cleanup { llvm::Value *V; CXXDestructorDecl *Dtor; CallMemberDtor(llvm::Value *V, CXXDestructorDecl *Dtor) : V(V), Dtor(Dtor) {} void Emit(CodeGenFunction &CGF, Flags flags) { CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete, /*ForVirtualBase=*/false, V); } }; } static bool hasTrivialCopyOrMoveConstructor(const CXXRecordDecl *Record, bool Moving) { return Moving ? Record->hasTrivialMoveConstructor() : Record->hasTrivialCopyConstructor(); } static void EmitMemberInitializer(CodeGenFunction &CGF, const CXXRecordDecl *ClassDecl, CXXCtorInitializer *MemberInit, const CXXConstructorDecl *Constructor, FunctionArgList &Args) { assert(MemberInit->isAnyMemberInitializer() && "Must have member initializer!"); assert(MemberInit->getInit() && "Must have initializer!"); // non-static data member initializers. FieldDecl *Field = MemberInit->getAnyMember(); QualType FieldType = Field->getType(); llvm::Value *ThisPtr = CGF.LoadCXXThis(); QualType RecordTy = CGF.getContext().getTypeDeclType(ClassDecl); LValue LHS = CGF.MakeNaturalAlignAddrLValue(ThisPtr, RecordTy); if (MemberInit->isIndirectMemberInitializer()) { // If we are initializing an anonymous union field, drill down to // the field. IndirectFieldDecl *IndirectField = MemberInit->getIndirectMember(); IndirectFieldDecl::chain_iterator I = IndirectField->chain_begin(), IEnd = IndirectField->chain_end(); for ( ; I != IEnd; ++I) LHS = CGF.EmitLValueForFieldInitialization(LHS, cast<FieldDecl>(*I)); FieldType = MemberInit->getIndirectMember()->getAnonField()->getType(); } else { LHS = CGF.EmitLValueForFieldInitialization(LHS, Field); } // Special case: if we are in a copy or move constructor, and we are copying // an array of PODs or classes with trivial copy constructors, ignore the // AST and perform the copy we know is equivalent. // FIXME: This is hacky at best... if we had a bit more explicit information // in the AST, we could generalize it more easily. const ConstantArrayType *Array = CGF.getContext().getAsConstantArrayType(FieldType); if (Array && Constructor->isImplicitlyDefined() && Constructor->isCopyOrMoveConstructor()) { QualType BaseElementTy = CGF.getContext().getBaseElementType(Array); const CXXRecordDecl *Record = BaseElementTy->getAsCXXRecordDecl(); if (BaseElementTy.isPODType(CGF.getContext()) || (Record && hasTrivialCopyOrMoveConstructor(Record, Constructor->isMoveConstructor()))) { // Find the source pointer. We knows it's the last argument because // we know we're in a copy constructor. unsigned SrcArgIndex = Args.size() - 1; llvm::Value *SrcPtr = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(Args[SrcArgIndex])); LValue ThisRHSLV = CGF.MakeNaturalAlignAddrLValue(SrcPtr, RecordTy); LValue Src = CGF.EmitLValueForFieldInitialization(ThisRHSLV, Field); // Copy the aggregate. CGF.EmitAggregateCopy(LHS.getAddress(), Src.getAddress(), FieldType, LHS.isVolatileQualified()); return; } } ArrayRef<VarDecl *> ArrayIndexes; if (MemberInit->getNumArrayIndices()) ArrayIndexes = MemberInit->getArrayIndexes(); CGF.EmitInitializerForField(Field, LHS, MemberInit->getInit(), ArrayIndexes); } void CodeGenFunction::EmitInitializerForField(FieldDecl *Field, LValue LHS, Expr *Init, ArrayRef<VarDecl *> ArrayIndexes) { QualType FieldType = Field->getType(); if (!hasAggregateLLVMType(FieldType)) { if (LHS.isSimple()) { EmitExprAsInit(Init, Field, LHS, false); } else { RValue RHS = RValue::get(EmitScalarExpr(Init)); EmitStoreThroughLValue(RHS, LHS); } } else if (FieldType->isAnyComplexType()) { EmitComplexExprIntoAddr(Init, LHS.getAddress(), LHS.isVolatileQualified()); } else { llvm::Value *ArrayIndexVar = 0; if (ArrayIndexes.size()) { llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); // The LHS is a pointer to the first object we'll be constructing, as // a flat array. QualType BaseElementTy = getContext().getBaseElementType(FieldType); llvm::Type *BasePtr = ConvertType(BaseElementTy); BasePtr = llvm::PointerType::getUnqual(BasePtr); llvm::Value *BaseAddrPtr = Builder.CreateBitCast(LHS.getAddress(), BasePtr); LHS = MakeAddrLValue(BaseAddrPtr, BaseElementTy); // Create an array index that will be used to walk over all of the // objects we're constructing. ArrayIndexVar = CreateTempAlloca(SizeTy, "object.index"); llvm::Value *Zero = llvm::Constant::getNullValue(SizeTy); Builder.CreateStore(Zero, ArrayIndexVar); // Emit the block variables for the array indices, if any. for (unsigned I = 0, N = ArrayIndexes.size(); I != N; ++I) EmitAutoVarDecl(*ArrayIndexes[I]); } EmitAggMemberInitializer(*this, LHS, Init, ArrayIndexVar, FieldType, ArrayIndexes, 0); if (!CGM.getLangOpts().Exceptions) return; // FIXME: If we have an array of classes w/ non-trivial destructors, // we need to destroy in reverse order of construction along the exception // path. const RecordType *RT = FieldType->getAs<RecordType>(); if (!RT) return; CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); if (!RD->hasTrivialDestructor()) EHStack.pushCleanup<CallMemberDtor>(EHCleanup, LHS.getAddress(), RD->getDestructor()); } } /// Checks whether the given constructor is a valid subject for the /// complete-to-base constructor delegation optimization, i.e. /// emitting the complete constructor as a simple call to the base /// constructor. static bool IsConstructorDelegationValid(const CXXConstructorDecl *Ctor) { // Currently we disable the optimization for classes with virtual // bases because (1) the addresses of parameter variables need to be // consistent across all initializers but (2) the delegate function // call necessarily creates a second copy of the parameter variable. // // The limiting example (purely theoretical AFAIK): // struct A { A(int &c) { c++; } }; // struct B : virtual A { // B(int count) : A(count) { printf("%d\n", count); } // }; // ...although even this example could in principle be emitted as a // delegation since the address of the parameter doesn't escape. if (Ctor->getParent()->getNumVBases()) { // TODO: white-list trivial vbase initializers. This case wouldn't // be subject to the restrictions below. // TODO: white-list cases where: // - there are no non-reference parameters to the constructor // - the initializers don't access any non-reference parameters // - the initializers don't take the address of non-reference // parameters // - etc. // If we ever add any of the above cases, remember that: // - function-try-blocks will always blacklist this optimization // - we need to perform the constructor prologue and cleanup in // EmitConstructorBody. return false; } // We also disable the optimization for variadic functions because // it's impossible to "re-pass" varargs. if (Ctor->getType()->getAs<FunctionProtoType>()->isVariadic()) return false; // FIXME: Decide if we can do a delegation of a delegating constructor. if (Ctor->isDelegatingConstructor()) return false; return true; } /// EmitConstructorBody - Emits the body of the current constructor. void CodeGenFunction::EmitConstructorBody(FunctionArgList &Args) { const CXXConstructorDecl *Ctor = cast<CXXConstructorDecl>(CurGD.getDecl()); CXXCtorType CtorType = CurGD.getCtorType(); // Before we go any further, try the complete->base constructor // delegation optimization. if (CtorType == Ctor_Complete && IsConstructorDelegationValid(Ctor) && CGM.getContext().getTargetInfo().getCXXABI() != CXXABI_Microsoft) { if (CGDebugInfo *DI = getDebugInfo()) DI->EmitLocation(Builder, Ctor->getLocEnd()); EmitDelegateCXXConstructorCall(Ctor, Ctor_Base, Args); return; } Stmt *Body = Ctor->getBody(); // Enter the function-try-block before the constructor prologue if // applicable. bool IsTryBody = (Body && isa<CXXTryStmt>(Body)); if (IsTryBody) EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true); EHScopeStack::stable_iterator CleanupDepth = EHStack.stable_begin(); // TODO: in restricted cases, we can emit the vbase initializers of // a complete ctor and then delegate to the base ctor. // Emit the constructor prologue, i.e. the base and member // initializers. EmitCtorPrologue(Ctor, CtorType, Args); // Emit the body of the statement. if (IsTryBody) EmitStmt(cast<CXXTryStmt>(Body)->getTryBlock()); else if (Body) EmitStmt(Body); // Emit any cleanup blocks associated with the member or base // initializers, which includes (along the exceptional path) the // destructors for those members and bases that were fully // constructed. PopCleanupBlocks(CleanupDepth); if (IsTryBody) ExitCXXTryStmt(*cast<CXXTryStmt>(Body), true); } /// EmitCtorPrologue - This routine generates necessary code to initialize /// base classes and non-static data members belonging to this constructor. void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD, CXXCtorType CtorType, FunctionArgList &Args) { if (CD->isDelegatingConstructor()) return EmitDelegatingCXXConstructorCall(CD, Args); const CXXRecordDecl *ClassDecl = CD->getParent(); SmallVector<CXXCtorInitializer *, 8> MemberInitializers; for (CXXConstructorDecl::init_const_iterator B = CD->init_begin(), E = CD->init_end(); B != E; ++B) { CXXCtorInitializer *Member = (*B); if (Member->isBaseInitializer()) { EmitBaseInitializer(*this, ClassDecl, Member, CtorType); } else { assert(Member->isAnyMemberInitializer() && "Delegating initializer on non-delegating constructor"); MemberInitializers.push_back(Member); } } InitializeVTablePointers(ClassDecl); for (unsigned I = 0, E = MemberInitializers.size(); I != E; ++I) EmitMemberInitializer(*this, ClassDecl, MemberInitializers[I], CD, Args); } static bool FieldHasTrivialDestructorBody(ASTContext &Context, const FieldDecl *Field); static bool HasTrivialDestructorBody(ASTContext &Context, const CXXRecordDecl *BaseClassDecl, const CXXRecordDecl *MostDerivedClassDecl) { // If the destructor is trivial we don't have to check anything else. if (BaseClassDecl->hasTrivialDestructor()) return true; if (!BaseClassDecl->getDestructor()->hasTrivialBody()) return false; // Check fields. for (CXXRecordDecl::field_iterator I = BaseClassDecl->field_begin(), E = BaseClassDecl->field_end(); I != E; ++I) { const FieldDecl *Field = *I; if (!FieldHasTrivialDestructorBody(Context, Field)) return false; } // Check non-virtual bases. for (CXXRecordDecl::base_class_const_iterator I = BaseClassDecl->bases_begin(), E = BaseClassDecl->bases_end(); I != E; ++I) { if (I->isVirtual()) continue; const CXXRecordDecl *NonVirtualBase = cast<CXXRecordDecl>(I->getType()->castAs<RecordType>()->getDecl()); if (!HasTrivialDestructorBody(Context, NonVirtualBase, MostDerivedClassDecl)) return false; } if (BaseClassDecl == MostDerivedClassDecl) { // Check virtual bases. for (CXXRecordDecl::base_class_const_iterator I = BaseClassDecl->vbases_begin(), E = BaseClassDecl->vbases_end(); I != E; ++I) { const CXXRecordDecl *VirtualBase = cast<CXXRecordDecl>(I->getType()->castAs<RecordType>()->getDecl()); if (!HasTrivialDestructorBody(Context, VirtualBase, MostDerivedClassDecl)) return false; } } return true; } static bool FieldHasTrivialDestructorBody(ASTContext &Context, const FieldDecl *Field) { QualType FieldBaseElementType = Context.getBaseElementType(Field->getType()); const RecordType *RT = FieldBaseElementType->getAs<RecordType>(); if (!RT) return true; CXXRecordDecl *FieldClassDecl = cast<CXXRecordDecl>(RT->getDecl()); return HasTrivialDestructorBody(Context, FieldClassDecl, FieldClassDecl); } /// CanSkipVTablePointerInitialization - Check whether we need to initialize /// any vtable pointers before calling this destructor. static bool CanSkipVTablePointerInitialization(ASTContext &Context, const CXXDestructorDecl *Dtor) { if (!Dtor->hasTrivialBody()) return false; // Check the fields. const CXXRecordDecl *ClassDecl = Dtor->getParent(); for (CXXRecordDecl::field_iterator I = ClassDecl->field_begin(), E = ClassDecl->field_end(); I != E; ++I) { const FieldDecl *Field = *I; if (!FieldHasTrivialDestructorBody(Context, Field)) return false; } return true; } /// EmitDestructorBody - Emits the body of the current destructor. void CodeGenFunction::EmitDestructorBody(FunctionArgList &Args) { const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CurGD.getDecl()); CXXDtorType DtorType = CurGD.getDtorType(); // The call to operator delete in a deleting destructor happens // outside of the function-try-block, which means it's always // possible to delegate the destructor body to the complete // destructor. Do so. if (DtorType == Dtor_Deleting) { EnterDtorCleanups(Dtor, Dtor_Deleting); EmitCXXDestructorCall(Dtor, Dtor_Complete, /*ForVirtualBase=*/false, LoadCXXThis()); PopCleanupBlock(); return; } Stmt *Body = Dtor->getBody(); // If the body is a function-try-block, enter the try before // anything else. bool isTryBody = (Body && isa<CXXTryStmt>(Body)); if (isTryBody) EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true); // Enter the epilogue cleanups. RunCleanupsScope DtorEpilogue(*this); // If this is the complete variant, just invoke the base variant; // the epilogue will destruct the virtual bases. But we can't do // this optimization if the body is a function-try-block, because // we'd introduce *two* handler blocks. switch (DtorType) { case Dtor_Deleting: llvm_unreachable("already handled deleting case"); case Dtor_Complete: // Enter the cleanup scopes for virtual bases. EnterDtorCleanups(Dtor, Dtor_Complete); if (!isTryBody && CGM.getContext().getTargetInfo().getCXXABI() != CXXABI_Microsoft) { EmitCXXDestructorCall(Dtor, Dtor_Base, /*ForVirtualBase=*/false, LoadCXXThis()); break; } // Fallthrough: act like we're in the base variant. case Dtor_Base: // Enter the cleanup scopes for fields and non-virtual bases. EnterDtorCleanups(Dtor, Dtor_Base); // Initialize the vtable pointers before entering the body. if (!CanSkipVTablePointerInitialization(getContext(), Dtor)) InitializeVTablePointers(Dtor->getParent()); if (isTryBody) EmitStmt(cast<CXXTryStmt>(Body)->getTryBlock()); else if (Body) EmitStmt(Body); else { assert(Dtor->isImplicit() && "bodyless dtor not implicit"); // nothing to do besides what's in the epilogue } // -fapple-kext must inline any call to this dtor into // the caller's body. if (getContext().getLangOpts().AppleKext) CurFn->addFnAttr(llvm::Attribute::AlwaysInline); break; } // Jump out through the epilogue cleanups. DtorEpilogue.ForceCleanup(); // Exit the try if applicable. if (isTryBody) ExitCXXTryStmt(*cast<CXXTryStmt>(Body), true); } namespace { /// Call the operator delete associated with the current destructor. struct CallDtorDelete : EHScopeStack::Cleanup { CallDtorDelete() {} void Emit(CodeGenFunction &CGF, Flags flags) { const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CGF.CurCodeDecl); const CXXRecordDecl *ClassDecl = Dtor->getParent(); CGF.EmitDeleteCall(Dtor->getOperatorDelete(), CGF.LoadCXXThis(), CGF.getContext().getTagDeclType(ClassDecl)); } }; class DestroyField : public EHScopeStack::Cleanup { const FieldDecl *field; CodeGenFunction::Destroyer *destroyer; bool useEHCleanupForArray; public: DestroyField(const FieldDecl *field, CodeGenFunction::Destroyer *destroyer, bool useEHCleanupForArray) : field(field), destroyer(destroyer), useEHCleanupForArray(useEHCleanupForArray) {} void Emit(CodeGenFunction &CGF, Flags flags) { // Find the address of the field. llvm::Value *thisValue = CGF.LoadCXXThis(); QualType RecordTy = CGF.getContext().getTagDeclType(field->getParent()); LValue ThisLV = CGF.MakeAddrLValue(thisValue, RecordTy); LValue LV = CGF.EmitLValueForField(ThisLV, field); assert(LV.isSimple()); CGF.emitDestroy(LV.getAddress(), field->getType(), destroyer, flags.isForNormalCleanup() && useEHCleanupForArray); } }; } /// EmitDtorEpilogue - Emit all code that comes at the end of class's /// destructor. This is to call destructors on members and base classes /// in reverse order of their construction. void CodeGenFunction::EnterDtorCleanups(const CXXDestructorDecl *DD, CXXDtorType DtorType) { assert(!DD->isTrivial() && "Should not emit dtor epilogue for trivial dtor!"); // The deleting-destructor phase just needs to call the appropriate // operator delete that Sema picked up. if (DtorType == Dtor_Deleting) { assert(DD->getOperatorDelete() && "operator delete missing - EmitDtorEpilogue"); EHStack.pushCleanup<CallDtorDelete>(NormalAndEHCleanup); return; } const CXXRecordDecl *ClassDecl = DD->getParent(); // Unions have no bases and do not call field destructors. if (ClassDecl->isUnion()) 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; // Anonymous union members do not have their destructors called. const RecordType *RT = type->getAsUnionType(); if (RT && RT->getDecl()->isAnonymousStructOrUnion()) 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 (getLangOpts().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().DebugInfo == CodeGenOptions::LimitedDebugInfo) { // 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().arrangeCXXMethodCall(Args, FPT, RequiredArgs::All), 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.getLangOpts().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().getLangOpts().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); llvm::StoreInst *Store = Builder.CreateStore(VTableAddressPoint, VTableField); CGM.DecorateInstruction(Store, CGM.getTBAAInfoForVTablePtr()); } 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()); llvm::Instruction *VTable = Builder.CreateLoad(VTablePtrSrc, "vtable"); CGM.DecorateInstruction(VTable, CGM.getTBAAInfoForVTablePtr()); return 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.getLangOpts().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::EmitForwardingCallToLambda(const CXXRecordDecl *lambda, CallArgList &callArgs) { // Lookup the call operator DeclarationName operatorName = getContext().DeclarationNames.getCXXOperatorName(OO_Call); CXXMethodDecl *callOperator = cast<CXXMethodDecl>(*lambda->lookup(operatorName).first); // Get the address of the call operator. const CGFunctionInfo &calleeFnInfo = CGM.getTypes().arrangeCXXMethodDeclaration(callOperator); llvm::Value *callee = CGM.GetAddrOfFunction(GlobalDecl(callOperator), CGM.getTypes().GetFunctionType(calleeFnInfo)); // Prepare the return slot. const FunctionProtoType *FPT = callOperator->getType()->castAs<FunctionProtoType>(); QualType resultType = FPT->getResultType(); ReturnValueSlot returnSlot; if (!resultType->isVoidType() && calleeFnInfo.getReturnInfo().getKind() == ABIArgInfo::Indirect && hasAggregateLLVMType(calleeFnInfo.getReturnType())) returnSlot = ReturnValueSlot(ReturnValue, resultType.isVolatileQualified()); // We don't need to separately arrange the call arguments because // the call can't be variadic anyway --- it's impossible to forward // variadic arguments. // Now emit our call. RValue RV = EmitCall(calleeFnInfo, callee, returnSlot, callArgs, callOperator); // If necessary, copy the returned value into the slot. if (!resultType->isVoidType() && returnSlot.isNull()) EmitReturnOfRValue(RV, resultType); } void CodeGenFunction::EmitLambdaBlockInvokeBody() { const BlockDecl *BD = BlockInfo->getBlockDecl(); const VarDecl *variable = BD->capture_begin()->getVariable(); const CXXRecordDecl *Lambda = variable->getType()->getAsCXXRecordDecl(); // Start building arguments for forwarding call CallArgList CallArgs; QualType ThisType = getContext().getPointerType(getContext().getRecordType(Lambda)); llvm::Value *ThisPtr = GetAddrOfBlockDecl(variable, false); CallArgs.add(RValue::get(ThisPtr), ThisType); // Add the rest of the parameters. for (BlockDecl::param_const_iterator I = BD->param_begin(), E = BD->param_end(); I != E; ++I) { ParmVarDecl *param = *I; EmitDelegateCallArg(CallArgs, param); } EmitForwardingCallToLambda(Lambda, CallArgs); } void CodeGenFunction::EmitLambdaToBlockPointerBody(FunctionArgList &Args) { if (cast<CXXMethodDecl>(CurFuncDecl)->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(CurFuncDecl, "lambda conversion to variadic function"); return; } EmitFunctionBody(Args); } void CodeGenFunction::EmitLambdaDelegatingInvokeBody(const CXXMethodDecl *MD) { const CXXRecordDecl *Lambda = MD->getParent(); // 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); } EmitForwardingCallToLambda(Lambda, CallArgs); } 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"); return; } EmitLambdaDelegatingInvokeBody(MD); }