//===--- CGExprCXX.cpp - Emit LLVM Code for C++ expressions ---------------===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // This contains code dealing with code generation of C++ expressions // //===----------------------------------------------------------------------===// #include "CGCUDARuntime.h" #include "CGCXXABI.h" #include "CGDebugInfo.h" #include "CGObjCRuntime.h" #include "CodeGenFunction.h" #include "ConstantEmitter.h" #include "TargetInfo.h" #include "clang/Basic/CodeGenOptions.h" #include "clang/CodeGen/CGFunctionInfo.h" #include "llvm/IR/Intrinsics.h" using namespace clang; using namespace CodeGen; namespace { struct MemberCallInfo { RequiredArgs ReqArgs; // Number of prefix arguments for the call. Ignores the `this` pointer. unsigned PrefixSize; }; } static MemberCallInfo commonEmitCXXMemberOrOperatorCall(CodeGenFunction &CGF, const CXXMethodDecl *MD, llvm::Value *This, llvm::Value *ImplicitParam, QualType ImplicitParamTy, const CallExpr *CE, CallArgList &Args, CallArgList *RtlArgs) { assert(CE == nullptr || isa(CE) || isa(CE)); assert(MD->isInstance() && "Trying to emit a member or operator call expr on a static method!"); // Push the this ptr. const CXXRecordDecl *RD = CGF.CGM.getCXXABI().getThisArgumentTypeForMethod(MD); Args.add(RValue::get(This), CGF.getTypes().DeriveThisType(RD, MD)); // If there is an implicit parameter (e.g. VTT), emit it. if (ImplicitParam) { Args.add(RValue::get(ImplicitParam), ImplicitParamTy); } const FunctionProtoType *FPT = MD->getType()->castAs(); RequiredArgs required = RequiredArgs::forPrototypePlus(FPT, Args.size()); unsigned PrefixSize = Args.size() - 1; // And the rest of the call args. if (RtlArgs) { // Special case: if the caller emitted the arguments right-to-left already // (prior to emitting the *this argument), we're done. This happens for // assignment operators. Args.addFrom(*RtlArgs); } else if (CE) { // Special case: skip first argument of CXXOperatorCall (it is "this"). unsigned ArgsToSkip = isa(CE) ? 1 : 0; CGF.EmitCallArgs(Args, FPT, drop_begin(CE->arguments(), ArgsToSkip), CE->getDirectCallee()); } else { assert( FPT->getNumParams() == 0 && "No CallExpr specified for function with non-zero number of arguments"); } return {required, PrefixSize}; } RValue CodeGenFunction::EmitCXXMemberOrOperatorCall( const CXXMethodDecl *MD, const CGCallee &Callee, ReturnValueSlot ReturnValue, llvm::Value *This, llvm::Value *ImplicitParam, QualType ImplicitParamTy, const CallExpr *CE, CallArgList *RtlArgs) { const FunctionProtoType *FPT = MD->getType()->castAs(); CallArgList Args; MemberCallInfo CallInfo = commonEmitCXXMemberOrOperatorCall( *this, MD, This, ImplicitParam, ImplicitParamTy, CE, Args, RtlArgs); auto &FnInfo = CGM.getTypes().arrangeCXXMethodCall( Args, FPT, CallInfo.ReqArgs, CallInfo.PrefixSize); return EmitCall(FnInfo, Callee, ReturnValue, Args, nullptr, CE && CE == MustTailCall, CE ? CE->getExprLoc() : SourceLocation()); } RValue CodeGenFunction::EmitCXXDestructorCall( GlobalDecl Dtor, const CGCallee &Callee, llvm::Value *This, QualType ThisTy, llvm::Value *ImplicitParam, QualType ImplicitParamTy, const CallExpr *CE) { const CXXMethodDecl *DtorDecl = cast(Dtor.getDecl()); assert(!ThisTy.isNull()); assert(ThisTy->getAsCXXRecordDecl() == DtorDecl->getParent() && "Pointer/Object mixup"); LangAS SrcAS = ThisTy.getAddressSpace(); LangAS DstAS = DtorDecl->getMethodQualifiers().getAddressSpace(); if (SrcAS != DstAS) { QualType DstTy = DtorDecl->getThisType(); llvm::Type *NewType = CGM.getTypes().ConvertType(DstTy); This = getTargetHooks().performAddrSpaceCast(*this, This, SrcAS, DstAS, NewType); } CallArgList Args; commonEmitCXXMemberOrOperatorCall(*this, DtorDecl, This, ImplicitParam, ImplicitParamTy, CE, Args, nullptr); return EmitCall(CGM.getTypes().arrangeCXXStructorDeclaration(Dtor), Callee, ReturnValueSlot(), Args, nullptr, CE && CE == MustTailCall, CE ? CE->getExprLoc() : SourceLocation{}); } RValue CodeGenFunction::EmitCXXPseudoDestructorExpr( const CXXPseudoDestructorExpr *E) { QualType DestroyedType = E->getDestroyedType(); if (DestroyedType.hasStrongOrWeakObjCLifetime()) { // Automatic Reference Counting: // If the pseudo-expression names a retainable object with weak or // strong lifetime, the object shall be released. Expr *BaseExpr = E->getBase(); Address BaseValue = Address::invalid(); Qualifiers BaseQuals; // If this is s.x, emit s as an lvalue. If it is s->x, emit s as a scalar. if (E->isArrow()) { BaseValue = EmitPointerWithAlignment(BaseExpr); const auto *PTy = BaseExpr->getType()->castAs(); BaseQuals = PTy->getPointeeType().getQualifiers(); } else { LValue BaseLV = EmitLValue(BaseExpr); BaseValue = BaseLV.getAddress(*this); QualType BaseTy = BaseExpr->getType(); BaseQuals = BaseTy.getQualifiers(); } switch (DestroyedType.getObjCLifetime()) { case Qualifiers::OCL_None: case Qualifiers::OCL_ExplicitNone: case Qualifiers::OCL_Autoreleasing: break; case Qualifiers::OCL_Strong: EmitARCRelease(Builder.CreateLoad(BaseValue, DestroyedType.isVolatileQualified()), ARCPreciseLifetime); break; case Qualifiers::OCL_Weak: EmitARCDestroyWeak(BaseValue); break; } } else { // C++ [expr.pseudo]p1: // The result shall only be used as the operand for the function call // operator (), and the result of such a call has type void. The only // effect is the evaluation of the postfix-expression before the dot or // arrow. EmitIgnoredExpr(E->getBase()); } return RValue::get(nullptr); } static CXXRecordDecl *getCXXRecord(const Expr *E) { QualType T = E->getType(); if (const PointerType *PTy = T->getAs()) T = PTy->getPointeeType(); const RecordType *Ty = T->castAs(); return cast(Ty->getDecl()); } // Note: This function also emit constructor calls to support a MSVC // extensions allowing explicit constructor function call. RValue CodeGenFunction::EmitCXXMemberCallExpr(const CXXMemberCallExpr *CE, ReturnValueSlot ReturnValue) { const Expr *callee = CE->getCallee()->IgnoreParens(); if (isa(callee)) return EmitCXXMemberPointerCallExpr(CE, ReturnValue); const MemberExpr *ME = cast(callee); const CXXMethodDecl *MD = cast(ME->getMemberDecl()); if (MD->isStatic()) { // The method is static, emit it as we would a regular call. CGCallee callee = CGCallee::forDirect(CGM.GetAddrOfFunction(MD), GlobalDecl(MD)); return EmitCall(getContext().getPointerType(MD->getType()), callee, CE, ReturnValue); } bool HasQualifier = ME->hasQualifier(); NestedNameSpecifier *Qualifier = HasQualifier ? ME->getQualifier() : nullptr; bool IsArrow = ME->isArrow(); const Expr *Base = ME->getBase(); return EmitCXXMemberOrOperatorMemberCallExpr( CE, MD, ReturnValue, HasQualifier, Qualifier, IsArrow, Base); } RValue CodeGenFunction::EmitCXXMemberOrOperatorMemberCallExpr( const CallExpr *CE, const CXXMethodDecl *MD, ReturnValueSlot ReturnValue, bool HasQualifier, NestedNameSpecifier *Qualifier, bool IsArrow, const Expr *Base) { assert(isa(CE) || isa(CE)); // Compute the object pointer. bool CanUseVirtualCall = MD->isVirtual() && !HasQualifier; const CXXMethodDecl *DevirtualizedMethod = nullptr; if (CanUseVirtualCall && MD->getDevirtualizedMethod(Base, getLangOpts().AppleKext)) { const CXXRecordDecl *BestDynamicDecl = Base->getBestDynamicClassType(); DevirtualizedMethod = MD->getCorrespondingMethodInClass(BestDynamicDecl); assert(DevirtualizedMethod); const CXXRecordDecl *DevirtualizedClass = DevirtualizedMethod->getParent(); const Expr *Inner = Base->IgnoreParenBaseCasts(); if (DevirtualizedMethod->getReturnType().getCanonicalType() != MD->getReturnType().getCanonicalType()) // If the return types are not the same, this might be a case where more // code needs to run to compensate for it. For example, the derived // method might return a type that inherits form from the return // type of MD and has a prefix. // For now we just avoid devirtualizing these covariant cases. DevirtualizedMethod = nullptr; else if (getCXXRecord(Inner) == DevirtualizedClass) // If the class of the Inner expression is where the dynamic method // is defined, build the this pointer from it. Base = Inner; else if (getCXXRecord(Base) != DevirtualizedClass) { // If the method is defined in a class that is not the best dynamic // one or the one of the full expression, we would have to build // a derived-to-base cast to compute the correct this pointer, but // we don't have support for that yet, so do a virtual call. DevirtualizedMethod = nullptr; } } bool TrivialForCodegen = MD->isTrivial() || (MD->isDefaulted() && MD->getParent()->isUnion()); bool TrivialAssignment = TrivialForCodegen && (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()) && !MD->getParent()->mayInsertExtraPadding(); // C++17 demands that we evaluate the RHS of a (possibly-compound) assignment // operator before the LHS. CallArgList RtlArgStorage; CallArgList *RtlArgs = nullptr; LValue TrivialAssignmentRHS; if (auto *OCE = dyn_cast(CE)) { if (OCE->isAssignmentOp()) { if (TrivialAssignment) { TrivialAssignmentRHS = EmitLValue(CE->getArg(1)); } else { RtlArgs = &RtlArgStorage; EmitCallArgs(*RtlArgs, MD->getType()->castAs(), drop_begin(CE->arguments(), 1), CE->getDirectCallee(), /*ParamsToSkip*/0, EvaluationOrder::ForceRightToLeft); } } } LValue This; if (IsArrow) { LValueBaseInfo BaseInfo; TBAAAccessInfo TBAAInfo; Address ThisValue = EmitPointerWithAlignment(Base, &BaseInfo, &TBAAInfo); This = MakeAddrLValue(ThisValue, Base->getType(), BaseInfo, TBAAInfo); } else { This = EmitLValue(Base); } if (const CXXConstructorDecl *Ctor = dyn_cast(MD)) { // This is the MSVC p->Ctor::Ctor(...) extension. We assume that's // constructing a new complete object of type Ctor. assert(!RtlArgs); assert(ReturnValue.isNull() && "Constructor shouldn't have return value"); CallArgList Args; commonEmitCXXMemberOrOperatorCall( *this, Ctor, This.getPointer(*this), /*ImplicitParam=*/nullptr, /*ImplicitParamTy=*/QualType(), CE, Args, nullptr); EmitCXXConstructorCall(Ctor, Ctor_Complete, /*ForVirtualBase=*/false, /*Delegating=*/false, This.getAddress(*this), Args, AggValueSlot::DoesNotOverlap, CE->getExprLoc(), /*NewPointerIsChecked=*/false); return RValue::get(nullptr); } if (TrivialForCodegen) { if (isa(MD)) return RValue::get(nullptr); if (TrivialAssignment) { // We don't like to generate the trivial copy/move assignment operator // when it isn't necessary; just produce the proper effect here. // It's important that we use the result of EmitLValue here rather than // emitting call arguments, in order to preserve TBAA information from // the RHS. LValue RHS = isa(CE) ? TrivialAssignmentRHS : EmitLValue(*CE->arg_begin()); EmitAggregateAssign(This, RHS, CE->getType()); return RValue::get(This.getPointer(*this)); } assert(MD->getParent()->mayInsertExtraPadding() && "unknown trivial member function"); } // Compute the function type we're calling. const CXXMethodDecl *CalleeDecl = DevirtualizedMethod ? DevirtualizedMethod : MD; const CGFunctionInfo *FInfo = nullptr; if (const auto *Dtor = dyn_cast(CalleeDecl)) FInfo = &CGM.getTypes().arrangeCXXStructorDeclaration( GlobalDecl(Dtor, Dtor_Complete)); else FInfo = &CGM.getTypes().arrangeCXXMethodDeclaration(CalleeDecl); llvm::FunctionType *Ty = CGM.getTypes().GetFunctionType(*FInfo); // C++11 [class.mfct.non-static]p2: // If a non-static member function of a class X is called for an object that // is not of type X, or of a type derived from X, the behavior is undefined. SourceLocation CallLoc; ASTContext &C = getContext(); if (CE) CallLoc = CE->getExprLoc(); SanitizerSet SkippedChecks; if (const auto *CMCE = dyn_cast(CE)) { auto *IOA = CMCE->getImplicitObjectArgument(); bool IsImplicitObjectCXXThis = IsWrappedCXXThis(IOA); if (IsImplicitObjectCXXThis) SkippedChecks.set(SanitizerKind::Alignment, true); if (IsImplicitObjectCXXThis || isa(IOA)) SkippedChecks.set(SanitizerKind::Null, true); } EmitTypeCheck(CodeGenFunction::TCK_MemberCall, CallLoc, This.getPointer(*this), C.getRecordType(CalleeDecl->getParent()), /*Alignment=*/CharUnits::Zero(), SkippedChecks); // C++ [class.virtual]p12: // Explicit qualification with the scope operator (5.1) suppresses the // virtual call mechanism. // // We also don't emit a virtual call if the base expression has a record type // because then we know what the type is. bool UseVirtualCall = CanUseVirtualCall && !DevirtualizedMethod; if (const CXXDestructorDecl *Dtor = dyn_cast(CalleeDecl)) { assert(CE->arg_begin() == CE->arg_end() && "Destructor shouldn't have explicit parameters"); assert(ReturnValue.isNull() && "Destructor shouldn't have return value"); if (UseVirtualCall) { CGM.getCXXABI().EmitVirtualDestructorCall(*this, Dtor, Dtor_Complete, This.getAddress(*this), cast(CE)); } else { GlobalDecl GD(Dtor, Dtor_Complete); CGCallee Callee; if (getLangOpts().AppleKext && Dtor->isVirtual() && HasQualifier) Callee = BuildAppleKextVirtualCall(Dtor, Qualifier, Ty); else if (!DevirtualizedMethod) Callee = CGCallee::forDirect(CGM.getAddrOfCXXStructor(GD, FInfo, Ty), GD); else { Callee = CGCallee::forDirect(CGM.GetAddrOfFunction(GD, Ty), GD); } QualType ThisTy = IsArrow ? Base->getType()->getPointeeType() : Base->getType(); EmitCXXDestructorCall(GD, Callee, This.getPointer(*this), ThisTy, /*ImplicitParam=*/nullptr, /*ImplicitParamTy=*/QualType(), CE); } return RValue::get(nullptr); } // FIXME: Uses of 'MD' past this point need to be audited. We may need to use // 'CalleeDecl' instead. CGCallee Callee; if (UseVirtualCall) { Callee = CGCallee::forVirtual(CE, MD, This.getAddress(*this), Ty); } else { if (SanOpts.has(SanitizerKind::CFINVCall) && MD->getParent()->isDynamicClass()) { llvm::Value *VTable; const CXXRecordDecl *RD; std::tie(VTable, RD) = CGM.getCXXABI().LoadVTablePtr( *this, This.getAddress(*this), CalleeDecl->getParent()); EmitVTablePtrCheckForCall(RD, VTable, CFITCK_NVCall, CE->getBeginLoc()); } if (getLangOpts().AppleKext && MD->isVirtual() && HasQualifier) Callee = BuildAppleKextVirtualCall(MD, Qualifier, Ty); else if (!DevirtualizedMethod) Callee = CGCallee::forDirect(CGM.GetAddrOfFunction(MD, Ty), GlobalDecl(MD)); else { Callee = CGCallee::forDirect(CGM.GetAddrOfFunction(DevirtualizedMethod, Ty), GlobalDecl(DevirtualizedMethod)); } } if (MD->isVirtual()) { Address NewThisAddr = CGM.getCXXABI().adjustThisArgumentForVirtualFunctionCall( *this, CalleeDecl, This.getAddress(*this), UseVirtualCall); This.setAddress(NewThisAddr); } return EmitCXXMemberOrOperatorCall( CalleeDecl, Callee, ReturnValue, This.getPointer(*this), /*ImplicitParam=*/nullptr, QualType(), CE, RtlArgs); } RValue CodeGenFunction::EmitCXXMemberPointerCallExpr(const CXXMemberCallExpr *E, ReturnValueSlot ReturnValue) { const BinaryOperator *BO = cast(E->getCallee()->IgnoreParens()); const Expr *BaseExpr = BO->getLHS(); const Expr *MemFnExpr = BO->getRHS(); const auto *MPT = MemFnExpr->getType()->castAs(); const auto *FPT = MPT->getPointeeType()->castAs(); const auto *RD = cast(MPT->getClass()->castAs()->getDecl()); // Emit the 'this' pointer. Address This = Address::invalid(); if (BO->getOpcode() == BO_PtrMemI) This = EmitPointerWithAlignment(BaseExpr); else This = EmitLValue(BaseExpr).getAddress(*this); EmitTypeCheck(TCK_MemberCall, E->getExprLoc(), This.getPointer(), QualType(MPT->getClass(), 0)); // Get the member function pointer. llvm::Value *MemFnPtr = EmitScalarExpr(MemFnExpr); // Ask the ABI to load the callee. Note that This is modified. llvm::Value *ThisPtrForCall = nullptr; CGCallee Callee = CGM.getCXXABI().EmitLoadOfMemberFunctionPointer(*this, BO, This, ThisPtrForCall, MemFnPtr, MPT); CallArgList Args; QualType ThisType = getContext().getPointerType(getContext().getTagDeclType(RD)); // Push the this ptr. Args.add(RValue::get(ThisPtrForCall), ThisType); RequiredArgs required = RequiredArgs::forPrototypePlus(FPT, 1); // And the rest of the call args EmitCallArgs(Args, FPT, E->arguments()); return EmitCall(CGM.getTypes().arrangeCXXMethodCall(Args, FPT, required, /*PrefixSize=*/0), Callee, ReturnValue, Args, nullptr, E == MustTailCall, E->getExprLoc()); } RValue CodeGenFunction::EmitCXXOperatorMemberCallExpr(const CXXOperatorCallExpr *E, const CXXMethodDecl *MD, ReturnValueSlot ReturnValue) { assert(MD->isInstance() && "Trying to emit a member call expr on a static method!"); return EmitCXXMemberOrOperatorMemberCallExpr( E, MD, ReturnValue, /*HasQualifier=*/false, /*Qualifier=*/nullptr, /*IsArrow=*/false, E->getArg(0)); } RValue CodeGenFunction::EmitCUDAKernelCallExpr(const CUDAKernelCallExpr *E, ReturnValueSlot ReturnValue) { return CGM.getCUDARuntime().EmitCUDAKernelCallExpr(*this, E, ReturnValue); } static void EmitNullBaseClassInitialization(CodeGenFunction &CGF, Address DestPtr, const CXXRecordDecl *Base) { if (Base->isEmpty()) return; DestPtr = CGF.Builder.CreateElementBitCast(DestPtr, CGF.Int8Ty); const ASTRecordLayout &Layout = CGF.getContext().getASTRecordLayout(Base); CharUnits NVSize = Layout.getNonVirtualSize(); // We cannot simply zero-initialize the entire base sub-object if vbptrs are // present, they are initialized by the most derived class before calling the // constructor. SmallVector, 1> Stores; Stores.emplace_back(CharUnits::Zero(), NVSize); // Each store is split by the existence of a vbptr. CharUnits VBPtrWidth = CGF.getPointerSize(); std::vector VBPtrOffsets = CGF.CGM.getCXXABI().getVBPtrOffsets(Base); for (CharUnits VBPtrOffset : VBPtrOffsets) { // Stop before we hit any virtual base pointers located in virtual bases. if (VBPtrOffset >= NVSize) break; std::pair LastStore = Stores.pop_back_val(); CharUnits LastStoreOffset = LastStore.first; CharUnits LastStoreSize = LastStore.second; CharUnits SplitBeforeOffset = LastStoreOffset; CharUnits SplitBeforeSize = VBPtrOffset - SplitBeforeOffset; assert(!SplitBeforeSize.isNegative() && "negative store size!"); if (!SplitBeforeSize.isZero()) Stores.emplace_back(SplitBeforeOffset, SplitBeforeSize); CharUnits SplitAfterOffset = VBPtrOffset + VBPtrWidth; CharUnits SplitAfterSize = LastStoreSize - SplitAfterOffset; assert(!SplitAfterSize.isNegative() && "negative store size!"); if (!SplitAfterSize.isZero()) Stores.emplace_back(SplitAfterOffset, SplitAfterSize); } // If the type contains a pointer to data member we can't memset it to zero. // Instead, create a null constant and copy it to the destination. // TODO: there are other patterns besides zero that we can usefully memset, // like -1, which happens to be the pattern used by member-pointers. // TODO: isZeroInitializable can be over-conservative in the case where a // virtual base contains a member pointer. llvm::Constant *NullConstantForBase = CGF.CGM.EmitNullConstantForBase(Base); if (!NullConstantForBase->isNullValue()) { llvm::GlobalVariable *NullVariable = new llvm::GlobalVariable( CGF.CGM.getModule(), NullConstantForBase->getType(), /*isConstant=*/true, llvm::GlobalVariable::PrivateLinkage, NullConstantForBase, Twine()); CharUnits Align = std::max(Layout.getNonVirtualAlignment(), DestPtr.getAlignment()); NullVariable->setAlignment(Align.getAsAlign()); Address SrcPtr = Address(CGF.EmitCastToVoidPtr(NullVariable), Align); // Get and call the appropriate llvm.memcpy overload. for (std::pair Store : Stores) { CharUnits StoreOffset = Store.first; CharUnits StoreSize = Store.second; llvm::Value *StoreSizeVal = CGF.CGM.getSize(StoreSize); CGF.Builder.CreateMemCpy( CGF.Builder.CreateConstInBoundsByteGEP(DestPtr, StoreOffset), CGF.Builder.CreateConstInBoundsByteGEP(SrcPtr, StoreOffset), StoreSizeVal); } // Otherwise, just memset the whole thing to zero. This is legal // because in LLVM, all default initializers (other than the ones we just // handled above) are guaranteed to have a bit pattern of all zeros. } else { for (std::pair Store : Stores) { CharUnits StoreOffset = Store.first; CharUnits StoreSize = Store.second; llvm::Value *StoreSizeVal = CGF.CGM.getSize(StoreSize); CGF.Builder.CreateMemSet( CGF.Builder.CreateConstInBoundsByteGEP(DestPtr, StoreOffset), CGF.Builder.getInt8(0), StoreSizeVal); } } } void CodeGenFunction::EmitCXXConstructExpr(const CXXConstructExpr *E, AggValueSlot Dest) { assert(!Dest.isIgnored() && "Must have a destination!"); const CXXConstructorDecl *CD = E->getConstructor(); // If we require zero initialization before (or instead of) calling the // constructor, as can be the case with a non-user-provided default // constructor, emit the zero initialization now, unless destination is // already zeroed. if (E->requiresZeroInitialization() && !Dest.isZeroed()) { switch (E->getConstructionKind()) { case CXXConstructExpr::CK_Delegating: case CXXConstructExpr::CK_Complete: EmitNullInitialization(Dest.getAddress(), E->getType()); break; case CXXConstructExpr::CK_VirtualBase: case CXXConstructExpr::CK_NonVirtualBase: EmitNullBaseClassInitialization(*this, Dest.getAddress(), CD->getParent()); break; } } // If this is a call to a trivial default constructor, do nothing. if (CD->isTrivial() && CD->isDefaultConstructor()) return; // Elide the constructor if we're constructing from a temporary. if (getLangOpts().ElideConstructors && E->isElidable()) { // FIXME: This only handles the simplest case, where the source object // is passed directly as the first argument to the constructor. // This should also handle stepping though implicit casts and // conversion sequences which involve two steps, with a // conversion operator followed by a converting constructor. const Expr *SrcObj = E->getArg(0); assert(SrcObj->isTemporaryObject(getContext(), CD->getParent())); assert( getContext().hasSameUnqualifiedType(E->getType(), SrcObj->getType())); EmitAggExpr(SrcObj, Dest); return; } if (const ArrayType *arrayType = getContext().getAsArrayType(E->getType())) { EmitCXXAggrConstructorCall(CD, arrayType, Dest.getAddress(), E, Dest.isSanitizerChecked()); } else { CXXCtorType Type = Ctor_Complete; bool ForVirtualBase = false; bool Delegating = false; switch (E->getConstructionKind()) { case CXXConstructExpr::CK_Delegating: // We should be emitting a constructor; GlobalDecl will assert this Type = CurGD.getCtorType(); Delegating = true; break; case CXXConstructExpr::CK_Complete: Type = Ctor_Complete; break; case CXXConstructExpr::CK_VirtualBase: ForVirtualBase = true; LLVM_FALLTHROUGH; case CXXConstructExpr::CK_NonVirtualBase: Type = Ctor_Base; } // Call the constructor. EmitCXXConstructorCall(CD, Type, ForVirtualBase, Delegating, Dest, E); } } void CodeGenFunction::EmitSynthesizedCXXCopyCtor(Address Dest, Address Src, const Expr *Exp) { if (const ExprWithCleanups *E = dyn_cast(Exp)) Exp = E->getSubExpr(); assert(isa(Exp) && "EmitSynthesizedCXXCopyCtor - unknown copy ctor expr"); const CXXConstructExpr* E = cast(Exp); const CXXConstructorDecl *CD = E->getConstructor(); RunCleanupsScope Scope(*this); // If we require zero initialization before (or instead of) calling the // constructor, as can be the case with a non-user-provided default // constructor, emit the zero initialization now. // FIXME. Do I still need this for a copy ctor synthesis? if (E->requiresZeroInitialization()) EmitNullInitialization(Dest, E->getType()); assert(!getContext().getAsConstantArrayType(E->getType()) && "EmitSynthesizedCXXCopyCtor - Copied-in Array"); EmitSynthesizedCXXCopyCtorCall(CD, Dest, Src, E); } static CharUnits CalculateCookiePadding(CodeGenFunction &CGF, const CXXNewExpr *E) { if (!E->isArray()) return CharUnits::Zero(); // No cookie is required if the operator new[] being used is the // reserved placement operator new[]. if (E->getOperatorNew()->isReservedGlobalPlacementOperator()) return CharUnits::Zero(); return CGF.CGM.getCXXABI().GetArrayCookieSize(E); } static llvm::Value *EmitCXXNewAllocSize(CodeGenFunction &CGF, const CXXNewExpr *e, unsigned minElements, llvm::Value *&numElements, llvm::Value *&sizeWithoutCookie) { QualType type = e->getAllocatedType(); if (!e->isArray()) { CharUnits typeSize = CGF.getContext().getTypeSizeInChars(type); sizeWithoutCookie = llvm::ConstantInt::get(CGF.SizeTy, typeSize.getQuantity()); return sizeWithoutCookie; } // The width of size_t. unsigned sizeWidth = CGF.SizeTy->getBitWidth(); // Figure out the cookie size. llvm::APInt cookieSize(sizeWidth, CalculateCookiePadding(CGF, e).getQuantity()); // Emit the array size expression. // We multiply the size of all dimensions for NumElements. // e.g for 'int[2][3]', ElemType is 'int' and NumElements is 6. numElements = ConstantEmitter(CGF).tryEmitAbstract(*e->getArraySize(), e->getType()); if (!numElements) numElements = CGF.EmitScalarExpr(*e->getArraySize()); assert(isa(numElements->getType())); // The number of elements can be have an arbitrary integer type; // essentially, we need to multiply it by a constant factor, add a // cookie size, and verify that the result is representable as a // size_t. That's just a gloss, though, and it's wrong in one // important way: if the count is negative, it's an error even if // the cookie size would bring the total size >= 0. bool isSigned = (*e->getArraySize())->getType()->isSignedIntegerOrEnumerationType(); llvm::IntegerType *numElementsType = cast(numElements->getType()); unsigned numElementsWidth = numElementsType->getBitWidth(); // Compute the constant factor. llvm::APInt arraySizeMultiplier(sizeWidth, 1); while (const ConstantArrayType *CAT = CGF.getContext().getAsConstantArrayType(type)) { type = CAT->getElementType(); arraySizeMultiplier *= CAT->getSize(); } CharUnits typeSize = CGF.getContext().getTypeSizeInChars(type); llvm::APInt typeSizeMultiplier(sizeWidth, typeSize.getQuantity()); typeSizeMultiplier *= arraySizeMultiplier; // This will be a size_t. llvm::Value *size; // If someone is doing 'new int[42]' there is no need to do a dynamic check. // Don't bloat the -O0 code. if (llvm::ConstantInt *numElementsC = dyn_cast(numElements)) { const llvm::APInt &count = numElementsC->getValue(); bool hasAnyOverflow = false; // If 'count' was a negative number, it's an overflow. if (isSigned && count.isNegative()) hasAnyOverflow = true; // We want to do all this arithmetic in size_t. If numElements is // wider than that, check whether it's already too big, and if so, // overflow. else if (numElementsWidth > sizeWidth && numElementsWidth - sizeWidth > count.countLeadingZeros()) hasAnyOverflow = true; // Okay, compute a count at the right width. llvm::APInt adjustedCount = count.zextOrTrunc(sizeWidth); // If there is a brace-initializer, we cannot allocate fewer elements than // there are initializers. If we do, that's treated like an overflow. if (adjustedCount.ult(minElements)) hasAnyOverflow = true; // Scale numElements by that. This might overflow, but we don't // care because it only overflows if allocationSize does, too, and // if that overflows then we shouldn't use this. numElements = llvm::ConstantInt::get(CGF.SizeTy, adjustedCount * arraySizeMultiplier); // Compute the size before cookie, and track whether it overflowed. bool overflow; llvm::APInt allocationSize = adjustedCount.umul_ov(typeSizeMultiplier, overflow); hasAnyOverflow |= overflow; // Add in the cookie, and check whether it's overflowed. if (cookieSize != 0) { // Save the current size without a cookie. This shouldn't be // used if there was overflow. sizeWithoutCookie = llvm::ConstantInt::get(CGF.SizeTy, allocationSize); allocationSize = allocationSize.uadd_ov(cookieSize, overflow); hasAnyOverflow |= overflow; } // On overflow, produce a -1 so operator new will fail. if (hasAnyOverflow) { size = llvm::Constant::getAllOnesValue(CGF.SizeTy); } else { size = llvm::ConstantInt::get(CGF.SizeTy, allocationSize); } // Otherwise, we might need to use the overflow intrinsics. } else { // There are up to five conditions we need to test for: // 1) if isSigned, we need to check whether numElements is negative; // 2) if numElementsWidth > sizeWidth, we need to check whether // numElements is larger than something representable in size_t; // 3) if minElements > 0, we need to check whether numElements is smaller // than that. // 4) we need to compute // sizeWithoutCookie := numElements * typeSizeMultiplier // and check whether it overflows; and // 5) if we need a cookie, we need to compute // size := sizeWithoutCookie + cookieSize // and check whether it overflows. llvm::Value *hasOverflow = nullptr; // If numElementsWidth > sizeWidth, then one way or another, we're // going to have to do a comparison for (2), and this happens to // take care of (1), too. if (numElementsWidth > sizeWidth) { llvm::APInt threshold(numElementsWidth, 1); threshold <<= sizeWidth; llvm::Value *thresholdV = llvm::ConstantInt::get(numElementsType, threshold); hasOverflow = CGF.Builder.CreateICmpUGE(numElements, thresholdV); numElements = CGF.Builder.CreateTrunc(numElements, CGF.SizeTy); // Otherwise, if we're signed, we want to sext up to size_t. } else if (isSigned) { if (numElementsWidth < sizeWidth) numElements = CGF.Builder.CreateSExt(numElements, CGF.SizeTy); // If there's a non-1 type size multiplier, then we can do the // signedness check at the same time as we do the multiply // because a negative number times anything will cause an // unsigned overflow. Otherwise, we have to do it here. But at least // in this case, we can subsume the >= minElements check. if (typeSizeMultiplier == 1) hasOverflow = CGF.Builder.CreateICmpSLT(numElements, llvm::ConstantInt::get(CGF.SizeTy, minElements)); // Otherwise, zext up to size_t if necessary. } else if (numElementsWidth < sizeWidth) { numElements = CGF.Builder.CreateZExt(numElements, CGF.SizeTy); } assert(numElements->getType() == CGF.SizeTy); if (minElements) { // Don't allow allocation of fewer elements than we have initializers. if (!hasOverflow) { hasOverflow = CGF.Builder.CreateICmpULT(numElements, llvm::ConstantInt::get(CGF.SizeTy, minElements)); } else if (numElementsWidth > sizeWidth) { // The other existing overflow subsumes this check. // We do an unsigned comparison, since any signed value < -1 is // taken care of either above or below. hasOverflow = CGF.Builder.CreateOr(hasOverflow, CGF.Builder.CreateICmpULT(numElements, llvm::ConstantInt::get(CGF.SizeTy, minElements))); } } size = numElements; // Multiply by the type size if necessary. This multiplier // includes all the factors for nested arrays. // // This step also causes numElements to be scaled up by the // nested-array factor if necessary. Overflow on this computation // can be ignored because the result shouldn't be used if // allocation fails. if (typeSizeMultiplier != 1) { llvm::Function *umul_with_overflow = CGF.CGM.getIntrinsic(llvm::Intrinsic::umul_with_overflow, CGF.SizeTy); llvm::Value *tsmV = llvm::ConstantInt::get(CGF.SizeTy, typeSizeMultiplier); llvm::Value *result = CGF.Builder.CreateCall(umul_with_overflow, {size, tsmV}); llvm::Value *overflowed = CGF.Builder.CreateExtractValue(result, 1); if (hasOverflow) hasOverflow = CGF.Builder.CreateOr(hasOverflow, overflowed); else hasOverflow = overflowed; size = CGF.Builder.CreateExtractValue(result, 0); // Also scale up numElements by the array size multiplier. if (arraySizeMultiplier != 1) { // If the base element type size is 1, then we can re-use the // multiply we just did. if (typeSize.isOne()) { assert(arraySizeMultiplier == typeSizeMultiplier); numElements = size; // Otherwise we need a separate multiply. } else { llvm::Value *asmV = llvm::ConstantInt::get(CGF.SizeTy, arraySizeMultiplier); numElements = CGF.Builder.CreateMul(numElements, asmV); } } } else { // numElements doesn't need to be scaled. assert(arraySizeMultiplier == 1); } // Add in the cookie size if necessary. if (cookieSize != 0) { sizeWithoutCookie = size; llvm::Function *uadd_with_overflow = CGF.CGM.getIntrinsic(llvm::Intrinsic::uadd_with_overflow, CGF.SizeTy); llvm::Value *cookieSizeV = llvm::ConstantInt::get(CGF.SizeTy, cookieSize); llvm::Value *result = CGF.Builder.CreateCall(uadd_with_overflow, {size, cookieSizeV}); llvm::Value *overflowed = CGF.Builder.CreateExtractValue(result, 1); if (hasOverflow) hasOverflow = CGF.Builder.CreateOr(hasOverflow, overflowed); else hasOverflow = overflowed; size = CGF.Builder.CreateExtractValue(result, 0); } // If we had any possibility of dynamic overflow, make a select to // overwrite 'size' with an all-ones value, which should cause // operator new to throw. if (hasOverflow) size = CGF.Builder.CreateSelect(hasOverflow, llvm::Constant::getAllOnesValue(CGF.SizeTy), size); } if (cookieSize == 0) sizeWithoutCookie = size; else assert(sizeWithoutCookie && "didn't set sizeWithoutCookie?"); return size; } static void StoreAnyExprIntoOneUnit(CodeGenFunction &CGF, const Expr *Init, QualType AllocType, Address NewPtr, AggValueSlot::Overlap_t MayOverlap) { // FIXME: Refactor with EmitExprAsInit. switch (CGF.getEvaluationKind(AllocType)) { case TEK_Scalar: CGF.EmitScalarInit(Init, nullptr, CGF.MakeAddrLValue(NewPtr, AllocType), false); return; case TEK_Complex: CGF.EmitComplexExprIntoLValue(Init, CGF.MakeAddrLValue(NewPtr, AllocType), /*isInit*/ true); return; case TEK_Aggregate: { AggValueSlot Slot = AggValueSlot::forAddr(NewPtr, AllocType.getQualifiers(), AggValueSlot::IsDestructed, AggValueSlot::DoesNotNeedGCBarriers, AggValueSlot::IsNotAliased, MayOverlap, AggValueSlot::IsNotZeroed, AggValueSlot::IsSanitizerChecked); CGF.EmitAggExpr(Init, Slot); return; } } llvm_unreachable("bad evaluation kind"); } void CodeGenFunction::EmitNewArrayInitializer( const CXXNewExpr *E, QualType ElementType, llvm::Type *ElementTy, Address BeginPtr, llvm::Value *NumElements, llvm::Value *AllocSizeWithoutCookie) { // If we have a type with trivial initialization and no initializer, // there's nothing to do. if (!E->hasInitializer()) return; Address CurPtr = BeginPtr; unsigned InitListElements = 0; const Expr *Init = E->getInitializer(); Address EndOfInit = Address::invalid(); QualType::DestructionKind DtorKind = ElementType.isDestructedType(); EHScopeStack::stable_iterator Cleanup; llvm::Instruction *CleanupDominator = nullptr; CharUnits ElementSize = getContext().getTypeSizeInChars(ElementType); CharUnits ElementAlign = BeginPtr.getAlignment().alignmentOfArrayElement(ElementSize); // Attempt to perform zero-initialization using memset. auto TryMemsetInitialization = [&]() -> bool { // FIXME: If the type is a pointer-to-data-member under the Itanium ABI, // we can initialize with a memset to -1. if (!CGM.getTypes().isZeroInitializable(ElementType)) return false; // Optimization: since zero initialization will just set the memory // to all zeroes, generate a single memset to do it in one shot. // Subtract out the size of any elements we've already initialized. auto *RemainingSize = AllocSizeWithoutCookie; if (InitListElements) { // We know this can't overflow; we check this when doing the allocation. auto *InitializedSize = llvm::ConstantInt::get( RemainingSize->getType(), getContext().getTypeSizeInChars(ElementType).getQuantity() * InitListElements); RemainingSize = Builder.CreateSub(RemainingSize, InitializedSize); } // Create the memset. Builder.CreateMemSet(CurPtr, Builder.getInt8(0), RemainingSize, false); return true; }; // If the initializer is an initializer list, first do the explicit elements. if (const InitListExpr *ILE = dyn_cast(Init)) { // Initializing from a (braced) string literal is a special case; the init // list element does not initialize a (single) array element. if (ILE->isStringLiteralInit()) { // Initialize the initial portion of length equal to that of the string // literal. The allocation must be for at least this much; we emitted a // check for that earlier. AggValueSlot Slot = AggValueSlot::forAddr(CurPtr, ElementType.getQualifiers(), AggValueSlot::IsDestructed, AggValueSlot::DoesNotNeedGCBarriers, AggValueSlot::IsNotAliased, AggValueSlot::DoesNotOverlap, AggValueSlot::IsNotZeroed, AggValueSlot::IsSanitizerChecked); EmitAggExpr(ILE->getInit(0), Slot); // Move past these elements. InitListElements = cast(ILE->getType()->getAsArrayTypeUnsafe()) ->getSize().getZExtValue(); CurPtr = Builder.CreateConstInBoundsGEP( CurPtr, InitListElements, "string.init.end"); // Zero out the rest, if any remain. llvm::ConstantInt *ConstNum = dyn_cast(NumElements); if (!ConstNum || !ConstNum->equalsInt(InitListElements)) { bool OK = TryMemsetInitialization(); (void)OK; assert(OK && "couldn't memset character type?"); } return; } InitListElements = ILE->getNumInits(); // If this is a multi-dimensional array new, we will initialize multiple // elements with each init list element. QualType AllocType = E->getAllocatedType(); if (const ConstantArrayType *CAT = dyn_cast_or_null( AllocType->getAsArrayTypeUnsafe())) { ElementTy = ConvertTypeForMem(AllocType); CurPtr = Builder.CreateElementBitCast(CurPtr, ElementTy); InitListElements *= getContext().getConstantArrayElementCount(CAT); } // Enter a partial-destruction Cleanup if necessary. if (needsEHCleanup(DtorKind)) { // In principle we could tell the Cleanup where we are more // directly, but the control flow can get so varied here that it // would actually be quite complex. Therefore we go through an // alloca. EndOfInit = CreateTempAlloca(BeginPtr.getType(), getPointerAlign(), "array.init.end"); CleanupDominator = Builder.CreateStore(BeginPtr.getPointer(), EndOfInit); pushIrregularPartialArrayCleanup(BeginPtr.getPointer(), EndOfInit, ElementType, ElementAlign, getDestroyer(DtorKind)); Cleanup = EHStack.stable_begin(); } CharUnits StartAlign = CurPtr.getAlignment(); for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i) { // Tell the cleanup that it needs to destroy up to this // element. TODO: some of these stores can be trivially // observed to be unnecessary. if (EndOfInit.isValid()) { auto FinishedPtr = Builder.CreateBitCast(CurPtr.getPointer(), BeginPtr.getType()); Builder.CreateStore(FinishedPtr, EndOfInit); } // FIXME: If the last initializer is an incomplete initializer list for // an array, and we have an array filler, we can fold together the two // initialization loops. StoreAnyExprIntoOneUnit(*this, ILE->getInit(i), ILE->getInit(i)->getType(), CurPtr, AggValueSlot::DoesNotOverlap); CurPtr = Address(Builder.CreateInBoundsGEP( CurPtr.getElementType(), CurPtr.getPointer(), Builder.getSize(1), "array.exp.next"), CurPtr.getElementType(), StartAlign.alignmentAtOffset((i + 1) * ElementSize)); } // The remaining elements are filled with the array filler expression. Init = ILE->getArrayFiller(); // Extract the initializer for the individual array elements by pulling // out the array filler from all the nested initializer lists. This avoids // generating a nested loop for the initialization. while (Init && Init->getType()->isConstantArrayType()) { auto *SubILE = dyn_cast(Init); if (!SubILE) break; assert(SubILE->getNumInits() == 0 && "explicit inits in array filler?"); Init = SubILE->getArrayFiller(); } // Switch back to initializing one base element at a time. CurPtr = Builder.CreateElementBitCast(CurPtr, BeginPtr.getElementType()); } // If all elements have already been initialized, skip any further // initialization. llvm::ConstantInt *ConstNum = dyn_cast(NumElements); if (ConstNum && ConstNum->getZExtValue() <= InitListElements) { // If there was a Cleanup, deactivate it. if (CleanupDominator) DeactivateCleanupBlock(Cleanup, CleanupDominator); return; } assert(Init && "have trailing elements to initialize but no initializer"); // If this is a constructor call, try to optimize it out, and failing that // emit a single loop to initialize all remaining elements. if (const CXXConstructExpr *CCE = dyn_cast(Init)) { CXXConstructorDecl *Ctor = CCE->getConstructor(); if (Ctor->isTrivial()) { // If new expression did not specify value-initialization, then there // is no initialization. if (!CCE->requiresZeroInitialization() || Ctor->getParent()->isEmpty()) return; if (TryMemsetInitialization()) return; } // Store the new Cleanup position for irregular Cleanups. // // FIXME: Share this cleanup with the constructor call emission rather than // having it create a cleanup of its own. if (EndOfInit.isValid()) Builder.CreateStore(CurPtr.getPointer(), EndOfInit); // Emit a constructor call loop to initialize the remaining elements. if (InitListElements) NumElements = Builder.CreateSub( NumElements, llvm::ConstantInt::get(NumElements->getType(), InitListElements)); EmitCXXAggrConstructorCall(Ctor, NumElements, CurPtr, CCE, /*NewPointerIsChecked*/true, CCE->requiresZeroInitialization()); return; } // If this is value-initialization, we can usually use memset. ImplicitValueInitExpr IVIE(ElementType); if (isa(Init)) { if (TryMemsetInitialization()) return; // Switch to an ImplicitValueInitExpr for the element type. This handles // only one case: multidimensional array new of pointers to members. In // all other cases, we already have an initializer for the array element. Init = &IVIE; } // At this point we should have found an initializer for the individual // elements of the array. assert(getContext().hasSameUnqualifiedType(ElementType, Init->getType()) && "got wrong type of element to initialize"); // If we have an empty initializer list, we can usually use memset. if (auto *ILE = dyn_cast(Init)) if (ILE->getNumInits() == 0 && TryMemsetInitialization()) return; // If we have a struct whose every field is value-initialized, we can // usually use memset. if (auto *ILE = dyn_cast(Init)) { if (const RecordType *RType = ILE->getType()->getAs()) { if (RType->getDecl()->isStruct()) { unsigned NumElements = 0; if (auto *CXXRD = dyn_cast(RType->getDecl())) NumElements = CXXRD->getNumBases(); for (auto *Field : RType->getDecl()->fields()) if (!Field->isUnnamedBitfield()) ++NumElements; // FIXME: Recurse into nested InitListExprs. if (ILE->getNumInits() == NumElements) for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i) if (!isa(ILE->getInit(i))) --NumElements; if (ILE->getNumInits() == NumElements && TryMemsetInitialization()) return; } } } // Create the loop blocks. llvm::BasicBlock *EntryBB = Builder.GetInsertBlock(); llvm::BasicBlock *LoopBB = createBasicBlock("new.loop"); llvm::BasicBlock *ContBB = createBasicBlock("new.loop.end"); // Find the end of the array, hoisted out of the loop. llvm::Value *EndPtr = Builder.CreateInBoundsGEP(BeginPtr.getElementType(), BeginPtr.getPointer(), NumElements, "array.end"); // If the number of elements isn't constant, we have to now check if there is // anything left to initialize. if (!ConstNum) { llvm::Value *IsEmpty = Builder.CreateICmpEQ(CurPtr.getPointer(), EndPtr, "array.isempty"); Builder.CreateCondBr(IsEmpty, ContBB, LoopBB); } // Enter the loop. EmitBlock(LoopBB); // Set up the current-element phi. llvm::PHINode *CurPtrPhi = Builder.CreatePHI(CurPtr.getType(), 2, "array.cur"); CurPtrPhi->addIncoming(CurPtr.getPointer(), EntryBB); CurPtr = Address(CurPtrPhi, ElementAlign); // Store the new Cleanup position for irregular Cleanups. if (EndOfInit.isValid()) Builder.CreateStore(CurPtr.getPointer(), EndOfInit); // Enter a partial-destruction Cleanup if necessary. if (!CleanupDominator && needsEHCleanup(DtorKind)) { pushRegularPartialArrayCleanup(BeginPtr.getPointer(), CurPtr.getPointer(), ElementType, ElementAlign, getDestroyer(DtorKind)); Cleanup = EHStack.stable_begin(); CleanupDominator = Builder.CreateUnreachable(); } // Emit the initializer into this element. StoreAnyExprIntoOneUnit(*this, Init, Init->getType(), CurPtr, AggValueSlot::DoesNotOverlap); // Leave the Cleanup if we entered one. if (CleanupDominator) { DeactivateCleanupBlock(Cleanup, CleanupDominator); CleanupDominator->eraseFromParent(); } // Advance to the next element by adjusting the pointer type as necessary. llvm::Value *NextPtr = Builder.CreateConstInBoundsGEP1_32(ElementTy, CurPtr.getPointer(), 1, "array.next"); // Check whether we've gotten to the end of the array and, if so, // exit the loop. llvm::Value *IsEnd = Builder.CreateICmpEQ(NextPtr, EndPtr, "array.atend"); Builder.CreateCondBr(IsEnd, ContBB, LoopBB); CurPtrPhi->addIncoming(NextPtr, Builder.GetInsertBlock()); EmitBlock(ContBB); } static void EmitNewInitializer(CodeGenFunction &CGF, const CXXNewExpr *E, QualType ElementType, llvm::Type *ElementTy, Address NewPtr, llvm::Value *NumElements, llvm::Value *AllocSizeWithoutCookie) { ApplyDebugLocation DL(CGF, E); if (E->isArray()) CGF.EmitNewArrayInitializer(E, ElementType, ElementTy, NewPtr, NumElements, AllocSizeWithoutCookie); else if (const Expr *Init = E->getInitializer()) StoreAnyExprIntoOneUnit(CGF, Init, E->getAllocatedType(), NewPtr, AggValueSlot::DoesNotOverlap); } /// Emit a call to an operator new or operator delete function, as implicitly /// created by new-expressions and delete-expressions. static RValue EmitNewDeleteCall(CodeGenFunction &CGF, const FunctionDecl *CalleeDecl, const FunctionProtoType *CalleeType, const CallArgList &Args) { llvm::CallBase *CallOrInvoke; llvm::Constant *CalleePtr = CGF.CGM.GetAddrOfFunction(CalleeDecl); CGCallee Callee = CGCallee::forDirect(CalleePtr, GlobalDecl(CalleeDecl)); RValue RV = CGF.EmitCall(CGF.CGM.getTypes().arrangeFreeFunctionCall( Args, CalleeType, /*ChainCall=*/false), Callee, ReturnValueSlot(), Args, &CallOrInvoke); /// C++1y [expr.new]p10: /// [In a new-expression,] an implementation is allowed to omit a call /// to a replaceable global allocation function. /// /// We model such elidable calls with the 'builtin' attribute. llvm::Function *Fn = dyn_cast(CalleePtr); if (CalleeDecl->isReplaceableGlobalAllocationFunction() && Fn && Fn->hasFnAttribute(llvm::Attribute::NoBuiltin)) { CallOrInvoke->addFnAttr(llvm::Attribute::Builtin); } return RV; } RValue CodeGenFunction::EmitBuiltinNewDeleteCall(const FunctionProtoType *Type, const CallExpr *TheCall, bool IsDelete) { CallArgList Args; EmitCallArgs(Args, Type, TheCall->arguments()); // Find the allocation or deallocation function that we're calling. ASTContext &Ctx = getContext(); DeclarationName Name = Ctx.DeclarationNames .getCXXOperatorName(IsDelete ? OO_Delete : OO_New); for (auto *Decl : Ctx.getTranslationUnitDecl()->lookup(Name)) if (auto *FD = dyn_cast(Decl)) if (Ctx.hasSameType(FD->getType(), QualType(Type, 0))) return EmitNewDeleteCall(*this, FD, Type, Args); llvm_unreachable("predeclared global operator new/delete is missing"); } namespace { /// The parameters to pass to a usual operator delete. struct UsualDeleteParams { bool DestroyingDelete = false; bool Size = false; bool Alignment = false; }; } static UsualDeleteParams getUsualDeleteParams(const FunctionDecl *FD) { UsualDeleteParams Params; const FunctionProtoType *FPT = FD->getType()->castAs(); auto AI = FPT->param_type_begin(), AE = FPT->param_type_end(); // The first argument is always a void*. ++AI; // The next parameter may be a std::destroying_delete_t. if (FD->isDestroyingOperatorDelete()) { Params.DestroyingDelete = true; assert(AI != AE); ++AI; } // Figure out what other parameters we should be implicitly passing. if (AI != AE && (*AI)->isIntegerType()) { Params.Size = true; ++AI; } if (AI != AE && (*AI)->isAlignValT()) { Params.Alignment = true; ++AI; } assert(AI == AE && "unexpected usual deallocation function parameter"); return Params; } namespace { /// A cleanup to call the given 'operator delete' function upon abnormal /// exit from a new expression. Templated on a traits type that deals with /// ensuring that the arguments dominate the cleanup if necessary. template class CallDeleteDuringNew final : public EHScopeStack::Cleanup { /// Type used to hold llvm::Value*s. typedef typename Traits::ValueTy ValueTy; /// Type used to hold RValues. typedef typename Traits::RValueTy RValueTy; struct PlacementArg { RValueTy ArgValue; QualType ArgType; }; unsigned NumPlacementArgs : 31; unsigned PassAlignmentToPlacementDelete : 1; const FunctionDecl *OperatorDelete; ValueTy Ptr; ValueTy AllocSize; CharUnits AllocAlign; PlacementArg *getPlacementArgs() { return reinterpret_cast(this + 1); } public: static size_t getExtraSize(size_t NumPlacementArgs) { return NumPlacementArgs * sizeof(PlacementArg); } CallDeleteDuringNew(size_t NumPlacementArgs, const FunctionDecl *OperatorDelete, ValueTy Ptr, ValueTy AllocSize, bool PassAlignmentToPlacementDelete, CharUnits AllocAlign) : NumPlacementArgs(NumPlacementArgs), PassAlignmentToPlacementDelete(PassAlignmentToPlacementDelete), OperatorDelete(OperatorDelete), Ptr(Ptr), AllocSize(AllocSize), AllocAlign(AllocAlign) {} void setPlacementArg(unsigned I, RValueTy Arg, QualType Type) { assert(I < NumPlacementArgs && "index out of range"); getPlacementArgs()[I] = {Arg, Type}; } void Emit(CodeGenFunction &CGF, Flags flags) override { const auto *FPT = OperatorDelete->getType()->castAs(); CallArgList DeleteArgs; // The first argument is always a void* (or C* for a destroying operator // delete for class type C). DeleteArgs.add(Traits::get(CGF, Ptr), FPT->getParamType(0)); // Figure out what other parameters we should be implicitly passing. UsualDeleteParams Params; if (NumPlacementArgs) { // A placement deallocation function is implicitly passed an alignment // if the placement allocation function was, but is never passed a size. Params.Alignment = PassAlignmentToPlacementDelete; } else { // For a non-placement new-expression, 'operator delete' can take a // size and/or an alignment if it has the right parameters. Params = getUsualDeleteParams(OperatorDelete); } assert(!Params.DestroyingDelete && "should not call destroying delete in a new-expression"); // The second argument can be a std::size_t (for non-placement delete). if (Params.Size) DeleteArgs.add(Traits::get(CGF, AllocSize), CGF.getContext().getSizeType()); // The next (second or third) argument can be a std::align_val_t, which // is an enum whose underlying type is std::size_t. // FIXME: Use the right type as the parameter type. Note that in a call // to operator delete(size_t, ...), we may not have it available. if (Params.Alignment) DeleteArgs.add(RValue::get(llvm::ConstantInt::get( CGF.SizeTy, AllocAlign.getQuantity())), CGF.getContext().getSizeType()); // Pass the rest of the arguments, which must match exactly. for (unsigned I = 0; I != NumPlacementArgs; ++I) { auto Arg = getPlacementArgs()[I]; DeleteArgs.add(Traits::get(CGF, Arg.ArgValue), Arg.ArgType); } // Call 'operator delete'. EmitNewDeleteCall(CGF, OperatorDelete, FPT, DeleteArgs); } }; } /// Enter a cleanup to call 'operator delete' if the initializer in a /// new-expression throws. static void EnterNewDeleteCleanup(CodeGenFunction &CGF, const CXXNewExpr *E, Address NewPtr, llvm::Value *AllocSize, CharUnits AllocAlign, const CallArgList &NewArgs) { unsigned NumNonPlacementArgs = E->passAlignment() ? 2 : 1; // If we're not inside a conditional branch, then the cleanup will // dominate and we can do the easier (and more efficient) thing. if (!CGF.isInConditionalBranch()) { struct DirectCleanupTraits { typedef llvm::Value *ValueTy; typedef RValue RValueTy; static RValue get(CodeGenFunction &, ValueTy V) { return RValue::get(V); } static RValue get(CodeGenFunction &, RValueTy V) { return V; } }; typedef CallDeleteDuringNew DirectCleanup; DirectCleanup *Cleanup = CGF.EHStack .pushCleanupWithExtra(EHCleanup, E->getNumPlacementArgs(), E->getOperatorDelete(), NewPtr.getPointer(), AllocSize, E->passAlignment(), AllocAlign); for (unsigned I = 0, N = E->getNumPlacementArgs(); I != N; ++I) { auto &Arg = NewArgs[I + NumNonPlacementArgs]; Cleanup->setPlacementArg(I, Arg.getRValue(CGF), Arg.Ty); } return; } // Otherwise, we need to save all this stuff. DominatingValue::saved_type SavedNewPtr = DominatingValue::save(CGF, RValue::get(NewPtr.getPointer())); DominatingValue::saved_type SavedAllocSize = DominatingValue::save(CGF, RValue::get(AllocSize)); struct ConditionalCleanupTraits { typedef DominatingValue::saved_type ValueTy; typedef DominatingValue::saved_type RValueTy; static RValue get(CodeGenFunction &CGF, ValueTy V) { return V.restore(CGF); } }; typedef CallDeleteDuringNew ConditionalCleanup; ConditionalCleanup *Cleanup = CGF.EHStack .pushCleanupWithExtra(EHCleanup, E->getNumPlacementArgs(), E->getOperatorDelete(), SavedNewPtr, SavedAllocSize, E->passAlignment(), AllocAlign); for (unsigned I = 0, N = E->getNumPlacementArgs(); I != N; ++I) { auto &Arg = NewArgs[I + NumNonPlacementArgs]; Cleanup->setPlacementArg( I, DominatingValue::save(CGF, Arg.getRValue(CGF)), Arg.Ty); } CGF.initFullExprCleanup(); } llvm::Value *CodeGenFunction::EmitCXXNewExpr(const CXXNewExpr *E) { // The element type being allocated. QualType allocType = getContext().getBaseElementType(E->getAllocatedType()); // 1. Build a call to the allocation function. FunctionDecl *allocator = E->getOperatorNew(); // If there is a brace-initializer, cannot allocate fewer elements than inits. unsigned minElements = 0; if (E->isArray() && E->hasInitializer()) { const InitListExpr *ILE = dyn_cast(E->getInitializer()); if (ILE && ILE->isStringLiteralInit()) minElements = cast(ILE->getType()->getAsArrayTypeUnsafe()) ->getSize().getZExtValue(); else if (ILE) minElements = ILE->getNumInits(); } llvm::Value *numElements = nullptr; llvm::Value *allocSizeWithoutCookie = nullptr; llvm::Value *allocSize = EmitCXXNewAllocSize(*this, E, minElements, numElements, allocSizeWithoutCookie); CharUnits allocAlign = getContext().getPreferredTypeAlignInChars(allocType); // Emit the allocation call. If the allocator is a global placement // operator, just "inline" it directly. Address allocation = Address::invalid(); CallArgList allocatorArgs; if (allocator->isReservedGlobalPlacementOperator()) { assert(E->getNumPlacementArgs() == 1); const Expr *arg = *E->placement_arguments().begin(); LValueBaseInfo BaseInfo; allocation = EmitPointerWithAlignment(arg, &BaseInfo); // The pointer expression will, in many cases, be an opaque void*. // In these cases, discard the computed alignment and use the // formal alignment of the allocated type. if (BaseInfo.getAlignmentSource() != AlignmentSource::Decl) allocation = allocation.withAlignment(allocAlign); // Set up allocatorArgs for the call to operator delete if it's not // the reserved global operator. if (E->getOperatorDelete() && !E->getOperatorDelete()->isReservedGlobalPlacementOperator()) { allocatorArgs.add(RValue::get(allocSize), getContext().getSizeType()); allocatorArgs.add(RValue::get(allocation.getPointer()), arg->getType()); } } else { const FunctionProtoType *allocatorType = allocator->getType()->castAs(); unsigned ParamsToSkip = 0; // The allocation size is the first argument. QualType sizeType = getContext().getSizeType(); allocatorArgs.add(RValue::get(allocSize), sizeType); ++ParamsToSkip; if (allocSize != allocSizeWithoutCookie) { CharUnits cookieAlign = getSizeAlign(); // FIXME: Ask the ABI. allocAlign = std::max(allocAlign, cookieAlign); } // The allocation alignment may be passed as the second argument. if (E->passAlignment()) { QualType AlignValT = sizeType; if (allocatorType->getNumParams() > 1) { AlignValT = allocatorType->getParamType(1); assert(getContext().hasSameUnqualifiedType( AlignValT->castAs()->getDecl()->getIntegerType(), sizeType) && "wrong type for alignment parameter"); ++ParamsToSkip; } else { // Corner case, passing alignment to 'operator new(size_t, ...)'. assert(allocator->isVariadic() && "can't pass alignment to allocator"); } allocatorArgs.add( RValue::get(llvm::ConstantInt::get(SizeTy, allocAlign.getQuantity())), AlignValT); } // FIXME: Why do we not pass a CalleeDecl here? EmitCallArgs(allocatorArgs, allocatorType, E->placement_arguments(), /*AC*/AbstractCallee(), /*ParamsToSkip*/ParamsToSkip); RValue RV = EmitNewDeleteCall(*this, allocator, allocatorType, allocatorArgs); // Set !heapallocsite metadata on the call to operator new. if (getDebugInfo()) if (auto *newCall = dyn_cast(RV.getScalarVal())) getDebugInfo()->addHeapAllocSiteMetadata(newCall, allocType, E->getExprLoc()); // If this was a call to a global replaceable allocation function that does // not take an alignment argument, the allocator is known to produce // storage that's suitably aligned for any object that fits, up to a known // threshold. Otherwise assume it's suitably aligned for the allocated type. CharUnits allocationAlign = allocAlign; if (!E->passAlignment() && allocator->isReplaceableGlobalAllocationFunction()) { unsigned AllocatorAlign = llvm::PowerOf2Floor(std::min( Target.getNewAlign(), getContext().getTypeSize(allocType))); allocationAlign = std::max( allocationAlign, getContext().toCharUnitsFromBits(AllocatorAlign)); } allocation = Address(RV.getScalarVal(), Int8Ty, allocationAlign); } // Emit a null check on the allocation result if the allocation // function is allowed to return null (because it has a non-throwing // exception spec or is the reserved placement new) and we have an // interesting initializer will be running sanitizers on the initialization. bool nullCheck = E->shouldNullCheckAllocation() && (!allocType.isPODType(getContext()) || E->hasInitializer() || sanitizePerformTypeCheck()); llvm::BasicBlock *nullCheckBB = nullptr; llvm::BasicBlock *contBB = nullptr; // The null-check means that the initializer is conditionally // evaluated. ConditionalEvaluation conditional(*this); if (nullCheck) { conditional.begin(*this); nullCheckBB = Builder.GetInsertBlock(); llvm::BasicBlock *notNullBB = createBasicBlock("new.notnull"); contBB = createBasicBlock("new.cont"); llvm::Value *isNull = Builder.CreateIsNull(allocation.getPointer(), "new.isnull"); Builder.CreateCondBr(isNull, contBB, notNullBB); EmitBlock(notNullBB); } // If there's an operator delete, enter a cleanup to call it if an // exception is thrown. EHScopeStack::stable_iterator operatorDeleteCleanup; llvm::Instruction *cleanupDominator = nullptr; if (E->getOperatorDelete() && !E->getOperatorDelete()->isReservedGlobalPlacementOperator()) { EnterNewDeleteCleanup(*this, E, allocation, allocSize, allocAlign, allocatorArgs); operatorDeleteCleanup = EHStack.stable_begin(); cleanupDominator = Builder.CreateUnreachable(); } assert((allocSize == allocSizeWithoutCookie) == CalculateCookiePadding(*this, E).isZero()); if (allocSize != allocSizeWithoutCookie) { assert(E->isArray()); allocation = CGM.getCXXABI().InitializeArrayCookie(*this, allocation, numElements, E, allocType); } llvm::Type *elementTy = ConvertTypeForMem(allocType); Address result = Builder.CreateElementBitCast(allocation, elementTy); // Passing pointer through launder.invariant.group to avoid propagation of // vptrs information which may be included in previous type. // To not break LTO with different optimizations levels, we do it regardless // of optimization level. if (CGM.getCodeGenOpts().StrictVTablePointers && allocator->isReservedGlobalPlacementOperator()) result = Builder.CreateLaunderInvariantGroup(result); // Emit sanitizer checks for pointer value now, so that in the case of an // array it was checked only once and not at each constructor call. We may // have already checked that the pointer is non-null. // FIXME: If we have an array cookie and a potentially-throwing allocator, // we'll null check the wrong pointer here. SanitizerSet SkippedChecks; SkippedChecks.set(SanitizerKind::Null, nullCheck); EmitTypeCheck(CodeGenFunction::TCK_ConstructorCall, E->getAllocatedTypeSourceInfo()->getTypeLoc().getBeginLoc(), result.getPointer(), allocType, result.getAlignment(), SkippedChecks, numElements); EmitNewInitializer(*this, E, allocType, elementTy, result, numElements, allocSizeWithoutCookie); if (E->isArray()) { // NewPtr is a pointer to the base element type. If we're // allocating an array of arrays, we'll need to cast back to the // array pointer type. llvm::Type *resultType = ConvertTypeForMem(E->getType()); if (result.getType() != resultType) result = Builder.CreateBitCast(result, resultType); } // Deactivate the 'operator delete' cleanup if we finished // initialization. if (operatorDeleteCleanup.isValid()) { DeactivateCleanupBlock(operatorDeleteCleanup, cleanupDominator); cleanupDominator->eraseFromParent(); } llvm::Value *resultPtr = result.getPointer(); if (nullCheck) { conditional.end(*this); llvm::BasicBlock *notNullBB = Builder.GetInsertBlock(); EmitBlock(contBB); llvm::PHINode *PHI = Builder.CreatePHI(resultPtr->getType(), 2); PHI->addIncoming(resultPtr, notNullBB); PHI->addIncoming(llvm::Constant::getNullValue(resultPtr->getType()), nullCheckBB); resultPtr = PHI; } return resultPtr; } void CodeGenFunction::EmitDeleteCall(const FunctionDecl *DeleteFD, llvm::Value *Ptr, QualType DeleteTy, llvm::Value *NumElements, CharUnits CookieSize) { assert((!NumElements && CookieSize.isZero()) || DeleteFD->getOverloadedOperator() == OO_Array_Delete); const auto *DeleteFTy = DeleteFD->getType()->castAs(); CallArgList DeleteArgs; auto Params = getUsualDeleteParams(DeleteFD); auto ParamTypeIt = DeleteFTy->param_type_begin(); // Pass the pointer itself. QualType ArgTy = *ParamTypeIt++; llvm::Value *DeletePtr = Builder.CreateBitCast(Ptr, ConvertType(ArgTy)); DeleteArgs.add(RValue::get(DeletePtr), ArgTy); // Pass the std::destroying_delete tag if present. llvm::AllocaInst *DestroyingDeleteTag = nullptr; if (Params.DestroyingDelete) { QualType DDTag = *ParamTypeIt++; llvm::Type *Ty = getTypes().ConvertType(DDTag); CharUnits Align = CGM.getNaturalTypeAlignment(DDTag); DestroyingDeleteTag = CreateTempAlloca(Ty, "destroying.delete.tag"); DestroyingDeleteTag->setAlignment(Align.getAsAlign()); DeleteArgs.add(RValue::getAggregate(Address(DestroyingDeleteTag, Align)), DDTag); } // Pass the size if the delete function has a size_t parameter. if (Params.Size) { QualType SizeType = *ParamTypeIt++; CharUnits DeleteTypeSize = getContext().getTypeSizeInChars(DeleteTy); llvm::Value *Size = llvm::ConstantInt::get(ConvertType(SizeType), DeleteTypeSize.getQuantity()); // For array new, multiply by the number of elements. if (NumElements) Size = Builder.CreateMul(Size, NumElements); // If there is a cookie, add the cookie size. if (!CookieSize.isZero()) Size = Builder.CreateAdd( Size, llvm::ConstantInt::get(SizeTy, CookieSize.getQuantity())); DeleteArgs.add(RValue::get(Size), SizeType); } // Pass the alignment if the delete function has an align_val_t parameter. if (Params.Alignment) { QualType AlignValType = *ParamTypeIt++; CharUnits DeleteTypeAlign = getContext().toCharUnitsFromBits(getContext().getTypeAlignIfKnown( DeleteTy, true /* NeedsPreferredAlignment */)); llvm::Value *Align = llvm::ConstantInt::get(ConvertType(AlignValType), DeleteTypeAlign.getQuantity()); DeleteArgs.add(RValue::get(Align), AlignValType); } assert(ParamTypeIt == DeleteFTy->param_type_end() && "unknown parameter to usual delete function"); // Emit the call to delete. EmitNewDeleteCall(*this, DeleteFD, DeleteFTy, DeleteArgs); // If call argument lowering didn't use the destroying_delete_t alloca, // remove it again. if (DestroyingDeleteTag && DestroyingDeleteTag->use_empty()) DestroyingDeleteTag->eraseFromParent(); } namespace { /// Calls the given 'operator delete' on a single object. struct CallObjectDelete final : EHScopeStack::Cleanup { llvm::Value *Ptr; const FunctionDecl *OperatorDelete; QualType ElementType; CallObjectDelete(llvm::Value *Ptr, const FunctionDecl *OperatorDelete, QualType ElementType) : Ptr(Ptr), OperatorDelete(OperatorDelete), ElementType(ElementType) {} void Emit(CodeGenFunction &CGF, Flags flags) override { CGF.EmitDeleteCall(OperatorDelete, Ptr, ElementType); } }; } void CodeGenFunction::pushCallObjectDeleteCleanup(const FunctionDecl *OperatorDelete, llvm::Value *CompletePtr, QualType ElementType) { EHStack.pushCleanup(NormalAndEHCleanup, CompletePtr, OperatorDelete, ElementType); } /// Emit the code for deleting a single object with a destroying operator /// delete. If the element type has a non-virtual destructor, Ptr has already /// been converted to the type of the parameter of 'operator delete'. Otherwise /// Ptr points to an object of the static type. static void EmitDestroyingObjectDelete(CodeGenFunction &CGF, const CXXDeleteExpr *DE, Address Ptr, QualType ElementType) { auto *Dtor = ElementType->getAsCXXRecordDecl()->getDestructor(); if (Dtor && Dtor->isVirtual()) CGF.CGM.getCXXABI().emitVirtualObjectDelete(CGF, DE, Ptr, ElementType, Dtor); else CGF.EmitDeleteCall(DE->getOperatorDelete(), Ptr.getPointer(), ElementType); } /// Emit the code for deleting a single object. /// \return \c true if we started emitting UnconditionalDeleteBlock, \c false /// if not. static bool EmitObjectDelete(CodeGenFunction &CGF, const CXXDeleteExpr *DE, Address Ptr, QualType ElementType, llvm::BasicBlock *UnconditionalDeleteBlock) { // C++11 [expr.delete]p3: // If the static type of the object to be deleted is different from its // dynamic type, the static type shall be a base class of the dynamic type // of the object to be deleted and the static type shall have a virtual // destructor or the behavior is undefined. CGF.EmitTypeCheck(CodeGenFunction::TCK_MemberCall, DE->getExprLoc(), Ptr.getPointer(), ElementType); const FunctionDecl *OperatorDelete = DE->getOperatorDelete(); assert(!OperatorDelete->isDestroyingOperatorDelete()); // Find the destructor for the type, if applicable. If the // destructor is virtual, we'll just emit the vcall and return. const CXXDestructorDecl *Dtor = nullptr; if (const RecordType *RT = ElementType->getAs()) { CXXRecordDecl *RD = cast(RT->getDecl()); if (RD->hasDefinition() && !RD->hasTrivialDestructor()) { Dtor = RD->getDestructor(); if (Dtor->isVirtual()) { bool UseVirtualCall = true; const Expr *Base = DE->getArgument(); if (auto *DevirtualizedDtor = dyn_cast_or_null( Dtor->getDevirtualizedMethod( Base, CGF.CGM.getLangOpts().AppleKext))) { UseVirtualCall = false; const CXXRecordDecl *DevirtualizedClass = DevirtualizedDtor->getParent(); if (declaresSameEntity(getCXXRecord(Base), DevirtualizedClass)) { // Devirtualized to the class of the base type (the type of the // whole expression). Dtor = DevirtualizedDtor; } else { // Devirtualized to some other type. Would need to cast the this // pointer to that type but we don't have support for that yet, so // do a virtual call. FIXME: handle the case where it is // devirtualized to the derived type (the type of the inner // expression) as in EmitCXXMemberOrOperatorMemberCallExpr. UseVirtualCall = true; } } if (UseVirtualCall) { CGF.CGM.getCXXABI().emitVirtualObjectDelete(CGF, DE, Ptr, ElementType, Dtor); return false; } } } } // Make sure that we call delete even if the dtor throws. // This doesn't have to a conditional cleanup because we're going // to pop it off in a second. CGF.EHStack.pushCleanup(NormalAndEHCleanup, Ptr.getPointer(), OperatorDelete, ElementType); if (Dtor) CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete, /*ForVirtualBase=*/false, /*Delegating=*/false, Ptr, ElementType); else if (auto Lifetime = ElementType.getObjCLifetime()) { switch (Lifetime) { case Qualifiers::OCL_None: case Qualifiers::OCL_ExplicitNone: case Qualifiers::OCL_Autoreleasing: break; case Qualifiers::OCL_Strong: CGF.EmitARCDestroyStrong(Ptr, ARCPreciseLifetime); break; case Qualifiers::OCL_Weak: CGF.EmitARCDestroyWeak(Ptr); break; } } // When optimizing for size, call 'operator delete' unconditionally. if (CGF.CGM.getCodeGenOpts().OptimizeSize > 1) { CGF.EmitBlock(UnconditionalDeleteBlock); CGF.PopCleanupBlock(); return true; } CGF.PopCleanupBlock(); return false; } namespace { /// Calls the given 'operator delete' on an array of objects. struct CallArrayDelete final : EHScopeStack::Cleanup { llvm::Value *Ptr; const FunctionDecl *OperatorDelete; llvm::Value *NumElements; QualType ElementType; CharUnits CookieSize; CallArrayDelete(llvm::Value *Ptr, const FunctionDecl *OperatorDelete, llvm::Value *NumElements, QualType ElementType, CharUnits CookieSize) : Ptr(Ptr), OperatorDelete(OperatorDelete), NumElements(NumElements), ElementType(ElementType), CookieSize(CookieSize) {} void Emit(CodeGenFunction &CGF, Flags flags) override { CGF.EmitDeleteCall(OperatorDelete, Ptr, ElementType, NumElements, CookieSize); } }; } /// Emit the code for deleting an array of objects. static void EmitArrayDelete(CodeGenFunction &CGF, const CXXDeleteExpr *E, Address deletedPtr, QualType elementType) { llvm::Value *numElements = nullptr; llvm::Value *allocatedPtr = nullptr; CharUnits cookieSize; CGF.CGM.getCXXABI().ReadArrayCookie(CGF, deletedPtr, E, elementType, numElements, allocatedPtr, cookieSize); assert(allocatedPtr && "ReadArrayCookie didn't set allocated pointer"); // Make sure that we call delete even if one of the dtors throws. const FunctionDecl *operatorDelete = E->getOperatorDelete(); CGF.EHStack.pushCleanup(NormalAndEHCleanup, allocatedPtr, operatorDelete, numElements, elementType, cookieSize); // Destroy the elements. if (QualType::DestructionKind dtorKind = elementType.isDestructedType()) { assert(numElements && "no element count for a type with a destructor!"); CharUnits elementSize = CGF.getContext().getTypeSizeInChars(elementType); CharUnits elementAlign = deletedPtr.getAlignment().alignmentOfArrayElement(elementSize); llvm::Value *arrayBegin = deletedPtr.getPointer(); llvm::Value *arrayEnd = CGF.Builder.CreateInBoundsGEP( deletedPtr.getElementType(), arrayBegin, numElements, "delete.end"); // Note that it is legal to allocate a zero-length array, and we // can never fold the check away because the length should always // come from a cookie. CGF.emitArrayDestroy(arrayBegin, arrayEnd, elementType, elementAlign, CGF.getDestroyer(dtorKind), /*checkZeroLength*/ true, CGF.needsEHCleanup(dtorKind)); } // Pop the cleanup block. CGF.PopCleanupBlock(); } void CodeGenFunction::EmitCXXDeleteExpr(const CXXDeleteExpr *E) { const Expr *Arg = E->getArgument(); Address Ptr = EmitPointerWithAlignment(Arg); // Null check the pointer. // // We could avoid this null check if we can determine that the object // destruction is trivial and doesn't require an array cookie; we can // unconditionally perform the operator delete call in that case. For now, we // assume that deleted pointers are null rarely enough that it's better to // keep the branch. This might be worth revisiting for a -O0 code size win. llvm::BasicBlock *DeleteNotNull = createBasicBlock("delete.notnull"); llvm::BasicBlock *DeleteEnd = createBasicBlock("delete.end"); llvm::Value *IsNull = Builder.CreateIsNull(Ptr.getPointer(), "isnull"); Builder.CreateCondBr(IsNull, DeleteEnd, DeleteNotNull); EmitBlock(DeleteNotNull); QualType DeleteTy = E->getDestroyedType(); // A destroying operator delete overrides the entire operation of the // delete expression. if (E->getOperatorDelete()->isDestroyingOperatorDelete()) { EmitDestroyingObjectDelete(*this, E, Ptr, DeleteTy); EmitBlock(DeleteEnd); return; } // We might be deleting a pointer to array. If so, GEP down to the // first non-array element. // (this assumes that A(*)[3][7] is converted to [3 x [7 x %A]]*) if (DeleteTy->isConstantArrayType()) { llvm::Value *Zero = Builder.getInt32(0); SmallVector GEP; GEP.push_back(Zero); // point at the outermost array // For each layer of array type we're pointing at: while (const ConstantArrayType *Arr = getContext().getAsConstantArrayType(DeleteTy)) { // 1. Unpeel the array type. DeleteTy = Arr->getElementType(); // 2. GEP to the first element of the array. GEP.push_back(Zero); } Ptr = Address(Builder.CreateInBoundsGEP(Ptr.getElementType(), Ptr.getPointer(), GEP, "del.first"), Ptr.getAlignment()); } assert(ConvertTypeForMem(DeleteTy) == Ptr.getElementType()); if (E->isArrayForm()) { EmitArrayDelete(*this, E, Ptr, DeleteTy); EmitBlock(DeleteEnd); } else { if (!EmitObjectDelete(*this, E, Ptr, DeleteTy, DeleteEnd)) EmitBlock(DeleteEnd); } } static bool isGLValueFromPointerDeref(const Expr *E) { E = E->IgnoreParens(); if (const auto *CE = dyn_cast(E)) { if (!CE->getSubExpr()->isGLValue()) return false; return isGLValueFromPointerDeref(CE->getSubExpr()); } if (const auto *OVE = dyn_cast(E)) return isGLValueFromPointerDeref(OVE->getSourceExpr()); if (const auto *BO = dyn_cast(E)) if (BO->getOpcode() == BO_Comma) return isGLValueFromPointerDeref(BO->getRHS()); if (const auto *ACO = dyn_cast(E)) return isGLValueFromPointerDeref(ACO->getTrueExpr()) || isGLValueFromPointerDeref(ACO->getFalseExpr()); // C++11 [expr.sub]p1: // The expression E1[E2] is identical (by definition) to *((E1)+(E2)) if (isa(E)) return true; if (const auto *UO = dyn_cast(E)) if (UO->getOpcode() == UO_Deref) return true; return false; } static llvm::Value *EmitTypeidFromVTable(CodeGenFunction &CGF, const Expr *E, llvm::Type *StdTypeInfoPtrTy) { // Get the vtable pointer. Address ThisPtr = CGF.EmitLValue(E).getAddress(CGF); QualType SrcRecordTy = E->getType(); // C++ [class.cdtor]p4: // If the operand of typeid refers to the object under construction or // destruction and the static type of the operand is neither the constructor // or destructor’s class nor one of its bases, the behavior is undefined. CGF.EmitTypeCheck(CodeGenFunction::TCK_DynamicOperation, E->getExprLoc(), ThisPtr.getPointer(), SrcRecordTy); // C++ [expr.typeid]p2: // If the glvalue expression is obtained by applying the unary * operator to // a pointer and the pointer is a null pointer value, the typeid expression // throws the std::bad_typeid exception. // // However, this paragraph's intent is not clear. We choose a very generous // interpretation which implores us to consider comma operators, conditional // operators, parentheses and other such constructs. if (CGF.CGM.getCXXABI().shouldTypeidBeNullChecked( isGLValueFromPointerDeref(E), SrcRecordTy)) { llvm::BasicBlock *BadTypeidBlock = CGF.createBasicBlock("typeid.bad_typeid"); llvm::BasicBlock *EndBlock = CGF.createBasicBlock("typeid.end"); llvm::Value *IsNull = CGF.Builder.CreateIsNull(ThisPtr.getPointer()); CGF.Builder.CreateCondBr(IsNull, BadTypeidBlock, EndBlock); CGF.EmitBlock(BadTypeidBlock); CGF.CGM.getCXXABI().EmitBadTypeidCall(CGF); CGF.EmitBlock(EndBlock); } return CGF.CGM.getCXXABI().EmitTypeid(CGF, SrcRecordTy, ThisPtr, StdTypeInfoPtrTy); } llvm::Value *CodeGenFunction::EmitCXXTypeidExpr(const CXXTypeidExpr *E) { llvm::Type *StdTypeInfoPtrTy = ConvertType(E->getType())->getPointerTo(); if (E->isTypeOperand()) { llvm::Constant *TypeInfo = CGM.GetAddrOfRTTIDescriptor(E->getTypeOperand(getContext())); return Builder.CreateBitCast(TypeInfo, StdTypeInfoPtrTy); } // C++ [expr.typeid]p2: // When typeid is applied to a glvalue expression whose type is a // polymorphic class type, the result refers to a std::type_info object // representing the type of the most derived object (that is, the dynamic // type) to which the glvalue refers. // If the operand is already most derived object, no need to look up vtable. if (E->isPotentiallyEvaluated() && !E->isMostDerived(getContext())) return EmitTypeidFromVTable(*this, E->getExprOperand(), StdTypeInfoPtrTy); QualType OperandTy = E->getExprOperand()->getType(); return Builder.CreateBitCast(CGM.GetAddrOfRTTIDescriptor(OperandTy), StdTypeInfoPtrTy); } static llvm::Value *EmitDynamicCastToNull(CodeGenFunction &CGF, QualType DestTy) { llvm::Type *DestLTy = CGF.ConvertType(DestTy); if (DestTy->isPointerType()) return llvm::Constant::getNullValue(DestLTy); /// C++ [expr.dynamic.cast]p9: /// A failed cast to reference type throws std::bad_cast if (!CGF.CGM.getCXXABI().EmitBadCastCall(CGF)) return nullptr; CGF.EmitBlock(CGF.createBasicBlock("dynamic_cast.end")); return llvm::UndefValue::get(DestLTy); } llvm::Value *CodeGenFunction::EmitDynamicCast(Address ThisAddr, const CXXDynamicCastExpr *DCE) { CGM.EmitExplicitCastExprType(DCE, this); QualType DestTy = DCE->getTypeAsWritten(); QualType SrcTy = DCE->getSubExpr()->getType(); // C++ [expr.dynamic.cast]p7: // If T is "pointer to cv void," then the result is a pointer to the most // derived object pointed to by v. const PointerType *DestPTy = DestTy->getAs(); bool isDynamicCastToVoid; QualType SrcRecordTy; QualType DestRecordTy; if (DestPTy) { isDynamicCastToVoid = DestPTy->getPointeeType()->isVoidType(); SrcRecordTy = SrcTy->castAs()->getPointeeType(); DestRecordTy = DestPTy->getPointeeType(); } else { isDynamicCastToVoid = false; SrcRecordTy = SrcTy; DestRecordTy = DestTy->castAs()->getPointeeType(); } // C++ [class.cdtor]p5: // If the operand of the dynamic_cast refers to the object under // construction or destruction and the static type of the operand is not a // pointer to or object of the constructor or destructor’s own class or one // of its bases, the dynamic_cast results in undefined behavior. EmitTypeCheck(TCK_DynamicOperation, DCE->getExprLoc(), ThisAddr.getPointer(), SrcRecordTy); if (DCE->isAlwaysNull()) if (llvm::Value *T = EmitDynamicCastToNull(*this, DestTy)) return T; assert(SrcRecordTy->isRecordType() && "source type must be a record type!"); // C++ [expr.dynamic.cast]p4: // If the value of v is a null pointer value in the pointer case, the result // is the null pointer value of type T. bool ShouldNullCheckSrcValue = CGM.getCXXABI().shouldDynamicCastCallBeNullChecked(SrcTy->isPointerType(), SrcRecordTy); llvm::BasicBlock *CastNull = nullptr; llvm::BasicBlock *CastNotNull = nullptr; llvm::BasicBlock *CastEnd = createBasicBlock("dynamic_cast.end"); if (ShouldNullCheckSrcValue) { CastNull = createBasicBlock("dynamic_cast.null"); CastNotNull = createBasicBlock("dynamic_cast.notnull"); llvm::Value *IsNull = Builder.CreateIsNull(ThisAddr.getPointer()); Builder.CreateCondBr(IsNull, CastNull, CastNotNull); EmitBlock(CastNotNull); } llvm::Value *Value; if (isDynamicCastToVoid) { Value = CGM.getCXXABI().EmitDynamicCastToVoid(*this, ThisAddr, SrcRecordTy, DestTy); } else { assert(DestRecordTy->isRecordType() && "destination type must be a record type!"); Value = CGM.getCXXABI().EmitDynamicCastCall(*this, ThisAddr, SrcRecordTy, DestTy, DestRecordTy, CastEnd); CastNotNull = Builder.GetInsertBlock(); } if (ShouldNullCheckSrcValue) { EmitBranch(CastEnd); EmitBlock(CastNull); EmitBranch(CastEnd); } EmitBlock(CastEnd); if (ShouldNullCheckSrcValue) { llvm::PHINode *PHI = Builder.CreatePHI(Value->getType(), 2); PHI->addIncoming(Value, CastNotNull); PHI->addIncoming(llvm::Constant::getNullValue(Value->getType()), CastNull); Value = PHI; } return Value; }