| //===--- VTableBuilder.cpp - C++ vtable layout builder --------------------===// |
| // |
| // 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 generation of the layout of virtual tables. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/AST/VTableBuilder.h" |
| #include "clang/AST/ASTContext.h" |
| #include "clang/AST/ASTDiagnostic.h" |
| #include "clang/AST/CXXInheritance.h" |
| #include "clang/AST/RecordLayout.h" |
| #include "clang/Basic/TargetInfo.h" |
| #include "llvm/ADT/SetOperations.h" |
| #include "llvm/ADT/SmallPtrSet.h" |
| #include "llvm/Support/Format.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include <algorithm> |
| #include <cstdio> |
| |
| using namespace clang; |
| |
| #define DUMP_OVERRIDERS 0 |
| |
| namespace { |
| |
| /// BaseOffset - Represents an offset from a derived class to a direct or |
| /// indirect base class. |
| struct BaseOffset { |
| /// DerivedClass - The derived class. |
| const CXXRecordDecl *DerivedClass; |
| |
| /// VirtualBase - If the path from the derived class to the base class |
| /// involves virtual base classes, this holds the declaration of the last |
| /// virtual base in this path (i.e. closest to the base class). |
| const CXXRecordDecl *VirtualBase; |
| |
| /// NonVirtualOffset - The offset from the derived class to the base class. |
| /// (Or the offset from the virtual base class to the base class, if the |
| /// path from the derived class to the base class involves a virtual base |
| /// class. |
| CharUnits NonVirtualOffset; |
| |
| BaseOffset() : DerivedClass(nullptr), VirtualBase(nullptr), |
| NonVirtualOffset(CharUnits::Zero()) { } |
| BaseOffset(const CXXRecordDecl *DerivedClass, |
| const CXXRecordDecl *VirtualBase, CharUnits NonVirtualOffset) |
| : DerivedClass(DerivedClass), VirtualBase(VirtualBase), |
| NonVirtualOffset(NonVirtualOffset) { } |
| |
| bool isEmpty() const { return NonVirtualOffset.isZero() && !VirtualBase; } |
| }; |
| |
| /// FinalOverriders - Contains the final overrider member functions for all |
| /// member functions in the base subobjects of a class. |
| class FinalOverriders { |
| public: |
| /// OverriderInfo - Information about a final overrider. |
| struct OverriderInfo { |
| /// Method - The method decl of the overrider. |
| const CXXMethodDecl *Method; |
| |
| /// VirtualBase - The virtual base class subobject of this overrider. |
| /// Note that this records the closest derived virtual base class subobject. |
| const CXXRecordDecl *VirtualBase; |
| |
| /// Offset - the base offset of the overrider's parent in the layout class. |
| CharUnits Offset; |
| |
| OverriderInfo() : Method(nullptr), VirtualBase(nullptr), |
| Offset(CharUnits::Zero()) { } |
| }; |
| |
| private: |
| /// MostDerivedClass - The most derived class for which the final overriders |
| /// are stored. |
| const CXXRecordDecl *MostDerivedClass; |
| |
| /// MostDerivedClassOffset - If we're building final overriders for a |
| /// construction vtable, this holds the offset from the layout class to the |
| /// most derived class. |
| const CharUnits MostDerivedClassOffset; |
| |
| /// LayoutClass - The class we're using for layout information. Will be |
| /// different than the most derived class if the final overriders are for a |
| /// construction vtable. |
| const CXXRecordDecl *LayoutClass; |
| |
| ASTContext &Context; |
| |
| /// MostDerivedClassLayout - the AST record layout of the most derived class. |
| const ASTRecordLayout &MostDerivedClassLayout; |
| |
| /// MethodBaseOffsetPairTy - Uniquely identifies a member function |
| /// in a base subobject. |
| typedef std::pair<const CXXMethodDecl *, CharUnits> MethodBaseOffsetPairTy; |
| |
| typedef llvm::DenseMap<MethodBaseOffsetPairTy, |
| OverriderInfo> OverridersMapTy; |
| |
| /// OverridersMap - The final overriders for all virtual member functions of |
| /// all the base subobjects of the most derived class. |
| OverridersMapTy OverridersMap; |
| |
| /// SubobjectsToOffsetsMapTy - A mapping from a base subobject (represented |
| /// as a record decl and a subobject number) and its offsets in the most |
| /// derived class as well as the layout class. |
| typedef llvm::DenseMap<std::pair<const CXXRecordDecl *, unsigned>, |
| CharUnits> SubobjectOffsetMapTy; |
| |
| typedef llvm::DenseMap<const CXXRecordDecl *, unsigned> SubobjectCountMapTy; |
| |
| /// ComputeBaseOffsets - Compute the offsets for all base subobjects of the |
| /// given base. |
| void ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual, |
| CharUnits OffsetInLayoutClass, |
| SubobjectOffsetMapTy &SubobjectOffsets, |
| SubobjectOffsetMapTy &SubobjectLayoutClassOffsets, |
| SubobjectCountMapTy &SubobjectCounts); |
| |
| typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy; |
| |
| /// dump - dump the final overriders for a base subobject, and all its direct |
| /// and indirect base subobjects. |
| void dump(raw_ostream &Out, BaseSubobject Base, |
| VisitedVirtualBasesSetTy& VisitedVirtualBases); |
| |
| public: |
| FinalOverriders(const CXXRecordDecl *MostDerivedClass, |
| CharUnits MostDerivedClassOffset, |
| const CXXRecordDecl *LayoutClass); |
| |
| /// getOverrider - Get the final overrider for the given method declaration in |
| /// the subobject with the given base offset. |
| OverriderInfo getOverrider(const CXXMethodDecl *MD, |
| CharUnits BaseOffset) const { |
| assert(OverridersMap.count(std::make_pair(MD, BaseOffset)) && |
| "Did not find overrider!"); |
| |
| return OverridersMap.lookup(std::make_pair(MD, BaseOffset)); |
| } |
| |
| /// dump - dump the final overriders. |
| void dump() { |
| VisitedVirtualBasesSetTy VisitedVirtualBases; |
| dump(llvm::errs(), BaseSubobject(MostDerivedClass, CharUnits::Zero()), |
| VisitedVirtualBases); |
| } |
| |
| }; |
| |
| FinalOverriders::FinalOverriders(const CXXRecordDecl *MostDerivedClass, |
| CharUnits MostDerivedClassOffset, |
| const CXXRecordDecl *LayoutClass) |
| : MostDerivedClass(MostDerivedClass), |
| MostDerivedClassOffset(MostDerivedClassOffset), LayoutClass(LayoutClass), |
| Context(MostDerivedClass->getASTContext()), |
| MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)) { |
| |
| // Compute base offsets. |
| SubobjectOffsetMapTy SubobjectOffsets; |
| SubobjectOffsetMapTy SubobjectLayoutClassOffsets; |
| SubobjectCountMapTy SubobjectCounts; |
| ComputeBaseOffsets(BaseSubobject(MostDerivedClass, CharUnits::Zero()), |
| /*IsVirtual=*/false, |
| MostDerivedClassOffset, |
| SubobjectOffsets, SubobjectLayoutClassOffsets, |
| SubobjectCounts); |
| |
| // Get the final overriders. |
| CXXFinalOverriderMap FinalOverriders; |
| MostDerivedClass->getFinalOverriders(FinalOverriders); |
| |
| for (const auto &Overrider : FinalOverriders) { |
| const CXXMethodDecl *MD = Overrider.first; |
| const OverridingMethods &Methods = Overrider.second; |
| |
| for (const auto &M : Methods) { |
| unsigned SubobjectNumber = M.first; |
| assert(SubobjectOffsets.count(std::make_pair(MD->getParent(), |
| SubobjectNumber)) && |
| "Did not find subobject offset!"); |
| |
| CharUnits BaseOffset = SubobjectOffsets[std::make_pair(MD->getParent(), |
| SubobjectNumber)]; |
| |
| assert(M.second.size() == 1 && "Final overrider is not unique!"); |
| const UniqueVirtualMethod &Method = M.second.front(); |
| |
| const CXXRecordDecl *OverriderRD = Method.Method->getParent(); |
| assert(SubobjectLayoutClassOffsets.count( |
| std::make_pair(OverriderRD, Method.Subobject)) |
| && "Did not find subobject offset!"); |
| CharUnits OverriderOffset = |
| SubobjectLayoutClassOffsets[std::make_pair(OverriderRD, |
| Method.Subobject)]; |
| |
| OverriderInfo& Overrider = OverridersMap[std::make_pair(MD, BaseOffset)]; |
| assert(!Overrider.Method && "Overrider should not exist yet!"); |
| |
| Overrider.Offset = OverriderOffset; |
| Overrider.Method = Method.Method; |
| Overrider.VirtualBase = Method.InVirtualSubobject; |
| } |
| } |
| |
| #if DUMP_OVERRIDERS |
| // And dump them (for now). |
| dump(); |
| #endif |
| } |
| |
| static BaseOffset ComputeBaseOffset(const ASTContext &Context, |
| const CXXRecordDecl *DerivedRD, |
| const CXXBasePath &Path) { |
| CharUnits NonVirtualOffset = CharUnits::Zero(); |
| |
| unsigned NonVirtualStart = 0; |
| const CXXRecordDecl *VirtualBase = nullptr; |
| |
| // First, look for the virtual base class. |
| for (int I = Path.size(), E = 0; I != E; --I) { |
| const CXXBasePathElement &Element = Path[I - 1]; |
| |
| if (Element.Base->isVirtual()) { |
| NonVirtualStart = I; |
| QualType VBaseType = Element.Base->getType(); |
| VirtualBase = VBaseType->getAsCXXRecordDecl(); |
| break; |
| } |
| } |
| |
| // Now compute the non-virtual offset. |
| for (unsigned I = NonVirtualStart, E = Path.size(); I != E; ++I) { |
| const CXXBasePathElement &Element = Path[I]; |
| |
| // Check the base class offset. |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(Element.Class); |
| |
| const CXXRecordDecl *Base = Element.Base->getType()->getAsCXXRecordDecl(); |
| |
| NonVirtualOffset += Layout.getBaseClassOffset(Base); |
| } |
| |
| // FIXME: This should probably use CharUnits or something. Maybe we should |
| // even change the base offsets in ASTRecordLayout to be specified in |
| // CharUnits. |
| return BaseOffset(DerivedRD, VirtualBase, NonVirtualOffset); |
| |
| } |
| |
| static BaseOffset ComputeBaseOffset(const ASTContext &Context, |
| const CXXRecordDecl *BaseRD, |
| const CXXRecordDecl *DerivedRD) { |
| CXXBasePaths Paths(/*FindAmbiguities=*/false, |
| /*RecordPaths=*/true, /*DetectVirtual=*/false); |
| |
| if (!DerivedRD->isDerivedFrom(BaseRD, Paths)) |
| llvm_unreachable("Class must be derived from the passed in base class!"); |
| |
| return ComputeBaseOffset(Context, DerivedRD, Paths.front()); |
| } |
| |
| static BaseOffset |
| ComputeReturnAdjustmentBaseOffset(ASTContext &Context, |
| const CXXMethodDecl *DerivedMD, |
| const CXXMethodDecl *BaseMD) { |
| const FunctionType *BaseFT = BaseMD->getType()->getAs<FunctionType>(); |
| const FunctionType *DerivedFT = DerivedMD->getType()->getAs<FunctionType>(); |
| |
| // Canonicalize the return types. |
| CanQualType CanDerivedReturnType = |
| Context.getCanonicalType(DerivedFT->getReturnType()); |
| CanQualType CanBaseReturnType = |
| Context.getCanonicalType(BaseFT->getReturnType()); |
| |
| assert(CanDerivedReturnType->getTypeClass() == |
| CanBaseReturnType->getTypeClass() && |
| "Types must have same type class!"); |
| |
| if (CanDerivedReturnType == CanBaseReturnType) { |
| // No adjustment needed. |
| return BaseOffset(); |
| } |
| |
| if (isa<ReferenceType>(CanDerivedReturnType)) { |
| CanDerivedReturnType = |
| CanDerivedReturnType->getAs<ReferenceType>()->getPointeeType(); |
| CanBaseReturnType = |
| CanBaseReturnType->getAs<ReferenceType>()->getPointeeType(); |
| } else if (isa<PointerType>(CanDerivedReturnType)) { |
| CanDerivedReturnType = |
| CanDerivedReturnType->getAs<PointerType>()->getPointeeType(); |
| CanBaseReturnType = |
| CanBaseReturnType->getAs<PointerType>()->getPointeeType(); |
| } else { |
| llvm_unreachable("Unexpected return type!"); |
| } |
| |
| // We need to compare unqualified types here; consider |
| // const T *Base::foo(); |
| // T *Derived::foo(); |
| if (CanDerivedReturnType.getUnqualifiedType() == |
| CanBaseReturnType.getUnqualifiedType()) { |
| // No adjustment needed. |
| return BaseOffset(); |
| } |
| |
| const CXXRecordDecl *DerivedRD = |
| cast<CXXRecordDecl>(cast<RecordType>(CanDerivedReturnType)->getDecl()); |
| |
| const CXXRecordDecl *BaseRD = |
| cast<CXXRecordDecl>(cast<RecordType>(CanBaseReturnType)->getDecl()); |
| |
| return ComputeBaseOffset(Context, BaseRD, DerivedRD); |
| } |
| |
| void |
| FinalOverriders::ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual, |
| CharUnits OffsetInLayoutClass, |
| SubobjectOffsetMapTy &SubobjectOffsets, |
| SubobjectOffsetMapTy &SubobjectLayoutClassOffsets, |
| SubobjectCountMapTy &SubobjectCounts) { |
| const CXXRecordDecl *RD = Base.getBase(); |
| |
| unsigned SubobjectNumber = 0; |
| if (!IsVirtual) |
| SubobjectNumber = ++SubobjectCounts[RD]; |
| |
| // Set up the subobject to offset mapping. |
| assert(!SubobjectOffsets.count(std::make_pair(RD, SubobjectNumber)) |
| && "Subobject offset already exists!"); |
| assert(!SubobjectLayoutClassOffsets.count(std::make_pair(RD, SubobjectNumber)) |
| && "Subobject offset already exists!"); |
| |
| SubobjectOffsets[std::make_pair(RD, SubobjectNumber)] = Base.getBaseOffset(); |
| SubobjectLayoutClassOffsets[std::make_pair(RD, SubobjectNumber)] = |
| OffsetInLayoutClass; |
| |
| // Traverse our bases. |
| for (const auto &B : RD->bases()) { |
| const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl(); |
| |
| CharUnits BaseOffset; |
| CharUnits BaseOffsetInLayoutClass; |
| if (B.isVirtual()) { |
| // Check if we've visited this virtual base before. |
| if (SubobjectOffsets.count(std::make_pair(BaseDecl, 0))) |
| continue; |
| |
| const ASTRecordLayout &LayoutClassLayout = |
| Context.getASTRecordLayout(LayoutClass); |
| |
| BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl); |
| BaseOffsetInLayoutClass = |
| LayoutClassLayout.getVBaseClassOffset(BaseDecl); |
| } else { |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| CharUnits Offset = Layout.getBaseClassOffset(BaseDecl); |
| |
| BaseOffset = Base.getBaseOffset() + Offset; |
| BaseOffsetInLayoutClass = OffsetInLayoutClass + Offset; |
| } |
| |
| ComputeBaseOffsets(BaseSubobject(BaseDecl, BaseOffset), |
| B.isVirtual(), BaseOffsetInLayoutClass, |
| SubobjectOffsets, SubobjectLayoutClassOffsets, |
| SubobjectCounts); |
| } |
| } |
| |
| void FinalOverriders::dump(raw_ostream &Out, BaseSubobject Base, |
| VisitedVirtualBasesSetTy &VisitedVirtualBases) { |
| const CXXRecordDecl *RD = Base.getBase(); |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| |
| for (const auto &B : RD->bases()) { |
| const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl(); |
| |
| // Ignore bases that don't have any virtual member functions. |
| if (!BaseDecl->isPolymorphic()) |
| continue; |
| |
| CharUnits BaseOffset; |
| if (B.isVirtual()) { |
| if (!VisitedVirtualBases.insert(BaseDecl).second) { |
| // We've visited this base before. |
| continue; |
| } |
| |
| BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl); |
| } else { |
| BaseOffset = Layout.getBaseClassOffset(BaseDecl) + Base.getBaseOffset(); |
| } |
| |
| dump(Out, BaseSubobject(BaseDecl, BaseOffset), VisitedVirtualBases); |
| } |
| |
| Out << "Final overriders for ("; |
| RD->printQualifiedName(Out); |
| Out << ", "; |
| Out << Base.getBaseOffset().getQuantity() << ")\n"; |
| |
| // Now dump the overriders for this base subobject. |
| for (const auto *MD : RD->methods()) { |
| if (!MD->isVirtual()) |
| continue; |
| MD = MD->getCanonicalDecl(); |
| |
| OverriderInfo Overrider = getOverrider(MD, Base.getBaseOffset()); |
| |
| Out << " "; |
| MD->printQualifiedName(Out); |
| Out << " - ("; |
| Overrider.Method->printQualifiedName(Out); |
| Out << ", " << Overrider.Offset.getQuantity() << ')'; |
| |
| BaseOffset Offset; |
| if (!Overrider.Method->isPure()) |
| Offset = ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD); |
| |
| if (!Offset.isEmpty()) { |
| Out << " [ret-adj: "; |
| if (Offset.VirtualBase) { |
| Offset.VirtualBase->printQualifiedName(Out); |
| Out << " vbase, "; |
| } |
| |
| Out << Offset.NonVirtualOffset.getQuantity() << " nv]"; |
| } |
| |
| Out << "\n"; |
| } |
| } |
| |
| /// VCallOffsetMap - Keeps track of vcall offsets when building a vtable. |
| struct VCallOffsetMap { |
| |
| typedef std::pair<const CXXMethodDecl *, CharUnits> MethodAndOffsetPairTy; |
| |
| /// Offsets - Keeps track of methods and their offsets. |
| // FIXME: This should be a real map and not a vector. |
| SmallVector<MethodAndOffsetPairTy, 16> Offsets; |
| |
| /// MethodsCanShareVCallOffset - Returns whether two virtual member functions |
| /// can share the same vcall offset. |
| static bool MethodsCanShareVCallOffset(const CXXMethodDecl *LHS, |
| const CXXMethodDecl *RHS); |
| |
| public: |
| /// AddVCallOffset - Adds a vcall offset to the map. Returns true if the |
| /// add was successful, or false if there was already a member function with |
| /// the same signature in the map. |
| bool AddVCallOffset(const CXXMethodDecl *MD, CharUnits OffsetOffset); |
| |
| /// getVCallOffsetOffset - Returns the vcall offset offset (relative to the |
| /// vtable address point) for the given virtual member function. |
| CharUnits getVCallOffsetOffset(const CXXMethodDecl *MD); |
| |
| // empty - Return whether the offset map is empty or not. |
| bool empty() const { return Offsets.empty(); } |
| }; |
| |
| static bool HasSameVirtualSignature(const CXXMethodDecl *LHS, |
| const CXXMethodDecl *RHS) { |
| const FunctionProtoType *LT = |
| cast<FunctionProtoType>(LHS->getType().getCanonicalType()); |
| const FunctionProtoType *RT = |
| cast<FunctionProtoType>(RHS->getType().getCanonicalType()); |
| |
| // Fast-path matches in the canonical types. |
| if (LT == RT) return true; |
| |
| // Force the signatures to match. We can't rely on the overrides |
| // list here because there isn't necessarily an inheritance |
| // relationship between the two methods. |
| if (LT->getMethodQuals() != RT->getMethodQuals()) |
| return false; |
| return LT->getParamTypes() == RT->getParamTypes(); |
| } |
| |
| bool VCallOffsetMap::MethodsCanShareVCallOffset(const CXXMethodDecl *LHS, |
| const CXXMethodDecl *RHS) { |
| assert(LHS->isVirtual() && "LHS must be virtual!"); |
| assert(RHS->isVirtual() && "LHS must be virtual!"); |
| |
| // A destructor can share a vcall offset with another destructor. |
| if (isa<CXXDestructorDecl>(LHS)) |
| return isa<CXXDestructorDecl>(RHS); |
| |
| // FIXME: We need to check more things here. |
| |
| // The methods must have the same name. |
| DeclarationName LHSName = LHS->getDeclName(); |
| DeclarationName RHSName = RHS->getDeclName(); |
| if (LHSName != RHSName) |
| return false; |
| |
| // And the same signatures. |
| return HasSameVirtualSignature(LHS, RHS); |
| } |
| |
| bool VCallOffsetMap::AddVCallOffset(const CXXMethodDecl *MD, |
| CharUnits OffsetOffset) { |
| // Check if we can reuse an offset. |
| for (const auto &OffsetPair : Offsets) { |
| if (MethodsCanShareVCallOffset(OffsetPair.first, MD)) |
| return false; |
| } |
| |
| // Add the offset. |
| Offsets.push_back(MethodAndOffsetPairTy(MD, OffsetOffset)); |
| return true; |
| } |
| |
| CharUnits VCallOffsetMap::getVCallOffsetOffset(const CXXMethodDecl *MD) { |
| // Look for an offset. |
| for (const auto &OffsetPair : Offsets) { |
| if (MethodsCanShareVCallOffset(OffsetPair.first, MD)) |
| return OffsetPair.second; |
| } |
| |
| llvm_unreachable("Should always find a vcall offset offset!"); |
| } |
| |
| /// VCallAndVBaseOffsetBuilder - Class for building vcall and vbase offsets. |
| class VCallAndVBaseOffsetBuilder { |
| public: |
| typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> |
| VBaseOffsetOffsetsMapTy; |
| |
| private: |
| /// MostDerivedClass - The most derived class for which we're building vcall |
| /// and vbase offsets. |
| const CXXRecordDecl *MostDerivedClass; |
| |
| /// LayoutClass - The class we're using for layout information. Will be |
| /// different than the most derived class if we're building a construction |
| /// vtable. |
| const CXXRecordDecl *LayoutClass; |
| |
| /// Context - The ASTContext which we will use for layout information. |
| ASTContext &Context; |
| |
| /// Components - vcall and vbase offset components |
| typedef SmallVector<VTableComponent, 64> VTableComponentVectorTy; |
| VTableComponentVectorTy Components; |
| |
| /// VisitedVirtualBases - Visited virtual bases. |
| llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases; |
| |
| /// VCallOffsets - Keeps track of vcall offsets. |
| VCallOffsetMap VCallOffsets; |
| |
| |
| /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets, |
| /// relative to the address point. |
| VBaseOffsetOffsetsMapTy VBaseOffsetOffsets; |
| |
| /// FinalOverriders - The final overriders of the most derived class. |
| /// (Can be null when we're not building a vtable of the most derived class). |
| const FinalOverriders *Overriders; |
| |
| /// AddVCallAndVBaseOffsets - Add vcall offsets and vbase offsets for the |
| /// given base subobject. |
| void AddVCallAndVBaseOffsets(BaseSubobject Base, bool BaseIsVirtual, |
| CharUnits RealBaseOffset); |
| |
| /// AddVCallOffsets - Add vcall offsets for the given base subobject. |
| void AddVCallOffsets(BaseSubobject Base, CharUnits VBaseOffset); |
| |
| /// AddVBaseOffsets - Add vbase offsets for the given class. |
| void AddVBaseOffsets(const CXXRecordDecl *Base, |
| CharUnits OffsetInLayoutClass); |
| |
| /// getCurrentOffsetOffset - Get the current vcall or vbase offset offset in |
| /// chars, relative to the vtable address point. |
| CharUnits getCurrentOffsetOffset() const; |
| |
| public: |
| VCallAndVBaseOffsetBuilder(const CXXRecordDecl *MostDerivedClass, |
| const CXXRecordDecl *LayoutClass, |
| const FinalOverriders *Overriders, |
| BaseSubobject Base, bool BaseIsVirtual, |
| CharUnits OffsetInLayoutClass) |
| : MostDerivedClass(MostDerivedClass), LayoutClass(LayoutClass), |
| Context(MostDerivedClass->getASTContext()), Overriders(Overriders) { |
| |
| // Add vcall and vbase offsets. |
| AddVCallAndVBaseOffsets(Base, BaseIsVirtual, OffsetInLayoutClass); |
| } |
| |
| /// Methods for iterating over the components. |
| typedef VTableComponentVectorTy::const_reverse_iterator const_iterator; |
| const_iterator components_begin() const { return Components.rbegin(); } |
| const_iterator components_end() const { return Components.rend(); } |
| |
| const VCallOffsetMap &getVCallOffsets() const { return VCallOffsets; } |
| const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const { |
| return VBaseOffsetOffsets; |
| } |
| }; |
| |
| void |
| VCallAndVBaseOffsetBuilder::AddVCallAndVBaseOffsets(BaseSubobject Base, |
| bool BaseIsVirtual, |
| CharUnits RealBaseOffset) { |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base.getBase()); |
| |
| // Itanium C++ ABI 2.5.2: |
| // ..in classes sharing a virtual table with a primary base class, the vcall |
| // and vbase offsets added by the derived class all come before the vcall |
| // and vbase offsets required by the base class, so that the latter may be |
| // laid out as required by the base class without regard to additions from |
| // the derived class(es). |
| |
| // (Since we're emitting the vcall and vbase offsets in reverse order, we'll |
| // emit them for the primary base first). |
| if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) { |
| bool PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual(); |
| |
| CharUnits PrimaryBaseOffset; |
| |
| // Get the base offset of the primary base. |
| if (PrimaryBaseIsVirtual) { |
| assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() && |
| "Primary vbase should have a zero offset!"); |
| |
| const ASTRecordLayout &MostDerivedClassLayout = |
| Context.getASTRecordLayout(MostDerivedClass); |
| |
| PrimaryBaseOffset = |
| MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase); |
| } else { |
| assert(Layout.getBaseClassOffset(PrimaryBase).isZero() && |
| "Primary base should have a zero offset!"); |
| |
| PrimaryBaseOffset = Base.getBaseOffset(); |
| } |
| |
| AddVCallAndVBaseOffsets( |
| BaseSubobject(PrimaryBase,PrimaryBaseOffset), |
| PrimaryBaseIsVirtual, RealBaseOffset); |
| } |
| |
| AddVBaseOffsets(Base.getBase(), RealBaseOffset); |
| |
| // We only want to add vcall offsets for virtual bases. |
| if (BaseIsVirtual) |
| AddVCallOffsets(Base, RealBaseOffset); |
| } |
| |
| CharUnits VCallAndVBaseOffsetBuilder::getCurrentOffsetOffset() const { |
| // OffsetIndex is the index of this vcall or vbase offset, relative to the |
| // vtable address point. (We subtract 3 to account for the information just |
| // above the address point, the RTTI info, the offset to top, and the |
| // vcall offset itself). |
| int64_t OffsetIndex = -(int64_t)(3 + Components.size()); |
| |
| CharUnits PointerWidth = |
| Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0)); |
| CharUnits OffsetOffset = PointerWidth * OffsetIndex; |
| return OffsetOffset; |
| } |
| |
| void VCallAndVBaseOffsetBuilder::AddVCallOffsets(BaseSubobject Base, |
| CharUnits VBaseOffset) { |
| const CXXRecordDecl *RD = Base.getBase(); |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| |
| const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); |
| |
| // Handle the primary base first. |
| // We only want to add vcall offsets if the base is non-virtual; a virtual |
| // primary base will have its vcall and vbase offsets emitted already. |
| if (PrimaryBase && !Layout.isPrimaryBaseVirtual()) { |
| // Get the base offset of the primary base. |
| assert(Layout.getBaseClassOffset(PrimaryBase).isZero() && |
| "Primary base should have a zero offset!"); |
| |
| AddVCallOffsets(BaseSubobject(PrimaryBase, Base.getBaseOffset()), |
| VBaseOffset); |
| } |
| |
| // Add the vcall offsets. |
| for (const auto *MD : RD->methods()) { |
| if (!MD->isVirtual()) |
| continue; |
| MD = MD->getCanonicalDecl(); |
| |
| CharUnits OffsetOffset = getCurrentOffsetOffset(); |
| |
| // Don't add a vcall offset if we already have one for this member function |
| // signature. |
| if (!VCallOffsets.AddVCallOffset(MD, OffsetOffset)) |
| continue; |
| |
| CharUnits Offset = CharUnits::Zero(); |
| |
| if (Overriders) { |
| // Get the final overrider. |
| FinalOverriders::OverriderInfo Overrider = |
| Overriders->getOverrider(MD, Base.getBaseOffset()); |
| |
| /// The vcall offset is the offset from the virtual base to the object |
| /// where the function was overridden. |
| Offset = Overrider.Offset - VBaseOffset; |
| } |
| |
| Components.push_back( |
| VTableComponent::MakeVCallOffset(Offset)); |
| } |
| |
| // And iterate over all non-virtual bases (ignoring the primary base). |
| for (const auto &B : RD->bases()) { |
| if (B.isVirtual()) |
| continue; |
| |
| const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl(); |
| if (BaseDecl == PrimaryBase) |
| continue; |
| |
| // Get the base offset of this base. |
| CharUnits BaseOffset = Base.getBaseOffset() + |
| Layout.getBaseClassOffset(BaseDecl); |
| |
| AddVCallOffsets(BaseSubobject(BaseDecl, BaseOffset), |
| VBaseOffset); |
| } |
| } |
| |
| void |
| VCallAndVBaseOffsetBuilder::AddVBaseOffsets(const CXXRecordDecl *RD, |
| CharUnits OffsetInLayoutClass) { |
| const ASTRecordLayout &LayoutClassLayout = |
| Context.getASTRecordLayout(LayoutClass); |
| |
| // Add vbase offsets. |
| for (const auto &B : RD->bases()) { |
| const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl(); |
| |
| // Check if this is a virtual base that we haven't visited before. |
| if (B.isVirtual() && VisitedVirtualBases.insert(BaseDecl).second) { |
| CharUnits Offset = |
| LayoutClassLayout.getVBaseClassOffset(BaseDecl) - OffsetInLayoutClass; |
| |
| // Add the vbase offset offset. |
| assert(!VBaseOffsetOffsets.count(BaseDecl) && |
| "vbase offset offset already exists!"); |
| |
| CharUnits VBaseOffsetOffset = getCurrentOffsetOffset(); |
| VBaseOffsetOffsets.insert( |
| std::make_pair(BaseDecl, VBaseOffsetOffset)); |
| |
| Components.push_back( |
| VTableComponent::MakeVBaseOffset(Offset)); |
| } |
| |
| // Check the base class looking for more vbase offsets. |
| AddVBaseOffsets(BaseDecl, OffsetInLayoutClass); |
| } |
| } |
| |
| /// ItaniumVTableBuilder - Class for building vtable layout information. |
| class ItaniumVTableBuilder { |
| public: |
| /// PrimaryBasesSetVectorTy - A set vector of direct and indirect |
| /// primary bases. |
| typedef llvm::SmallSetVector<const CXXRecordDecl *, 8> |
| PrimaryBasesSetVectorTy; |
| |
| typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> |
| VBaseOffsetOffsetsMapTy; |
| |
| typedef VTableLayout::AddressPointsMapTy AddressPointsMapTy; |
| |
| typedef llvm::DenseMap<GlobalDecl, int64_t> MethodVTableIndicesTy; |
| |
| private: |
| /// VTables - Global vtable information. |
| ItaniumVTableContext &VTables; |
| |
| /// MostDerivedClass - The most derived class for which we're building this |
| /// vtable. |
| const CXXRecordDecl *MostDerivedClass; |
| |
| /// MostDerivedClassOffset - If we're building a construction vtable, this |
| /// holds the offset from the layout class to the most derived class. |
| const CharUnits MostDerivedClassOffset; |
| |
| /// MostDerivedClassIsVirtual - Whether the most derived class is a virtual |
| /// base. (This only makes sense when building a construction vtable). |
| bool MostDerivedClassIsVirtual; |
| |
| /// LayoutClass - The class we're using for layout information. Will be |
| /// different than the most derived class if we're building a construction |
| /// vtable. |
| const CXXRecordDecl *LayoutClass; |
| |
| /// Context - The ASTContext which we will use for layout information. |
| ASTContext &Context; |
| |
| /// FinalOverriders - The final overriders of the most derived class. |
| const FinalOverriders Overriders; |
| |
| /// VCallOffsetsForVBases - Keeps track of vcall offsets for the virtual |
| /// bases in this vtable. |
| llvm::DenseMap<const CXXRecordDecl *, VCallOffsetMap> VCallOffsetsForVBases; |
| |
| /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets for |
| /// the most derived class. |
| VBaseOffsetOffsetsMapTy VBaseOffsetOffsets; |
| |
| /// Components - The components of the vtable being built. |
| SmallVector<VTableComponent, 64> Components; |
| |
| /// AddressPoints - Address points for the vtable being built. |
| AddressPointsMapTy AddressPoints; |
| |
| /// MethodInfo - Contains information about a method in a vtable. |
| /// (Used for computing 'this' pointer adjustment thunks. |
| struct MethodInfo { |
| /// BaseOffset - The base offset of this method. |
| const CharUnits BaseOffset; |
| |
| /// BaseOffsetInLayoutClass - The base offset in the layout class of this |
| /// method. |
| const CharUnits BaseOffsetInLayoutClass; |
| |
| /// VTableIndex - The index in the vtable that this method has. |
| /// (For destructors, this is the index of the complete destructor). |
| const uint64_t VTableIndex; |
| |
| MethodInfo(CharUnits BaseOffset, CharUnits BaseOffsetInLayoutClass, |
| uint64_t VTableIndex) |
| : BaseOffset(BaseOffset), |
| BaseOffsetInLayoutClass(BaseOffsetInLayoutClass), |
| VTableIndex(VTableIndex) { } |
| |
| MethodInfo() |
| : BaseOffset(CharUnits::Zero()), |
| BaseOffsetInLayoutClass(CharUnits::Zero()), |
| VTableIndex(0) { } |
| |
| MethodInfo(MethodInfo const&) = default; |
| }; |
| |
| typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy; |
| |
| /// MethodInfoMap - The information for all methods in the vtable we're |
| /// currently building. |
| MethodInfoMapTy MethodInfoMap; |
| |
| /// MethodVTableIndices - Contains the index (relative to the vtable address |
| /// point) where the function pointer for a virtual function is stored. |
| MethodVTableIndicesTy MethodVTableIndices; |
| |
| typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy; |
| |
| /// VTableThunks - The thunks by vtable index in the vtable currently being |
| /// built. |
| VTableThunksMapTy VTableThunks; |
| |
| typedef SmallVector<ThunkInfo, 1> ThunkInfoVectorTy; |
| typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy; |
| |
| /// Thunks - A map that contains all the thunks needed for all methods in the |
| /// most derived class for which the vtable is currently being built. |
| ThunksMapTy Thunks; |
| |
| /// AddThunk - Add a thunk for the given method. |
| void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk); |
| |
| /// ComputeThisAdjustments - Compute the 'this' pointer adjustments for the |
| /// part of the vtable we're currently building. |
| void ComputeThisAdjustments(); |
| |
| typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy; |
| |
| /// PrimaryVirtualBases - All known virtual bases who are a primary base of |
| /// some other base. |
| VisitedVirtualBasesSetTy PrimaryVirtualBases; |
| |
| /// ComputeReturnAdjustment - Compute the return adjustment given a return |
| /// adjustment base offset. |
| ReturnAdjustment ComputeReturnAdjustment(BaseOffset Offset); |
| |
| /// ComputeThisAdjustmentBaseOffset - Compute the base offset for adjusting |
| /// the 'this' pointer from the base subobject to the derived subobject. |
| BaseOffset ComputeThisAdjustmentBaseOffset(BaseSubobject Base, |
| BaseSubobject Derived) const; |
| |
| /// ComputeThisAdjustment - Compute the 'this' pointer adjustment for the |
| /// given virtual member function, its offset in the layout class and its |
| /// final overrider. |
| ThisAdjustment |
| ComputeThisAdjustment(const CXXMethodDecl *MD, |
| CharUnits BaseOffsetInLayoutClass, |
| FinalOverriders::OverriderInfo Overrider); |
| |
| /// AddMethod - Add a single virtual member function to the vtable |
| /// components vector. |
| void AddMethod(const CXXMethodDecl *MD, ReturnAdjustment ReturnAdjustment); |
| |
| /// IsOverriderUsed - Returns whether the overrider will ever be used in this |
| /// part of the vtable. |
| /// |
| /// Itanium C++ ABI 2.5.2: |
| /// |
| /// struct A { virtual void f(); }; |
| /// struct B : virtual public A { int i; }; |
| /// struct C : virtual public A { int j; }; |
| /// struct D : public B, public C {}; |
| /// |
| /// When B and C are declared, A is a primary base in each case, so although |
| /// vcall offsets are allocated in the A-in-B and A-in-C vtables, no this |
| /// adjustment is required and no thunk is generated. However, inside D |
| /// objects, A is no longer a primary base of C, so if we allowed calls to |
| /// C::f() to use the copy of A's vtable in the C subobject, we would need |
| /// to adjust this from C* to B::A*, which would require a third-party |
| /// thunk. Since we require that a call to C::f() first convert to A*, |
| /// C-in-D's copy of A's vtable is never referenced, so this is not |
| /// necessary. |
| bool IsOverriderUsed(const CXXMethodDecl *Overrider, |
| CharUnits BaseOffsetInLayoutClass, |
| const CXXRecordDecl *FirstBaseInPrimaryBaseChain, |
| CharUnits FirstBaseOffsetInLayoutClass) const; |
| |
| |
| /// AddMethods - Add the methods of this base subobject and all its |
| /// primary bases to the vtable components vector. |
| void AddMethods(BaseSubobject Base, CharUnits BaseOffsetInLayoutClass, |
| const CXXRecordDecl *FirstBaseInPrimaryBaseChain, |
| CharUnits FirstBaseOffsetInLayoutClass, |
| PrimaryBasesSetVectorTy &PrimaryBases); |
| |
| // LayoutVTable - Layout the vtable for the given base class, including its |
| // secondary vtables and any vtables for virtual bases. |
| void LayoutVTable(); |
| |
| /// LayoutPrimaryAndSecondaryVTables - Layout the primary vtable for the |
| /// given base subobject, as well as all its secondary vtables. |
| /// |
| /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base |
| /// or a direct or indirect base of a virtual base. |
| /// |
| /// \param BaseIsVirtualInLayoutClass - Whether the base subobject is virtual |
| /// in the layout class. |
| void LayoutPrimaryAndSecondaryVTables(BaseSubobject Base, |
| bool BaseIsMorallyVirtual, |
| bool BaseIsVirtualInLayoutClass, |
| CharUnits OffsetInLayoutClass); |
| |
| /// LayoutSecondaryVTables - Layout the secondary vtables for the given base |
| /// subobject. |
| /// |
| /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base |
| /// or a direct or indirect base of a virtual base. |
| void LayoutSecondaryVTables(BaseSubobject Base, bool BaseIsMorallyVirtual, |
| CharUnits OffsetInLayoutClass); |
| |
| /// DeterminePrimaryVirtualBases - Determine the primary virtual bases in this |
| /// class hierarchy. |
| void DeterminePrimaryVirtualBases(const CXXRecordDecl *RD, |
| CharUnits OffsetInLayoutClass, |
| VisitedVirtualBasesSetTy &VBases); |
| |
| /// LayoutVTablesForVirtualBases - Layout vtables for all virtual bases of the |
| /// given base (excluding any primary bases). |
| void LayoutVTablesForVirtualBases(const CXXRecordDecl *RD, |
| VisitedVirtualBasesSetTy &VBases); |
| |
| /// isBuildingConstructionVTable - Return whether this vtable builder is |
| /// building a construction vtable. |
| bool isBuildingConstructorVTable() const { |
| return MostDerivedClass != LayoutClass; |
| } |
| |
| public: |
| /// Component indices of the first component of each of the vtables in the |
| /// vtable group. |
| SmallVector<size_t, 4> VTableIndices; |
| |
| ItaniumVTableBuilder(ItaniumVTableContext &VTables, |
| const CXXRecordDecl *MostDerivedClass, |
| CharUnits MostDerivedClassOffset, |
| bool MostDerivedClassIsVirtual, |
| const CXXRecordDecl *LayoutClass) |
| : VTables(VTables), MostDerivedClass(MostDerivedClass), |
| MostDerivedClassOffset(MostDerivedClassOffset), |
| MostDerivedClassIsVirtual(MostDerivedClassIsVirtual), |
| LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()), |
| Overriders(MostDerivedClass, MostDerivedClassOffset, LayoutClass) { |
| assert(!Context.getTargetInfo().getCXXABI().isMicrosoft()); |
| |
| LayoutVTable(); |
| |
| if (Context.getLangOpts().DumpVTableLayouts) |
| dumpLayout(llvm::outs()); |
| } |
| |
| uint64_t getNumThunks() const { |
| return Thunks.size(); |
| } |
| |
| ThunksMapTy::const_iterator thunks_begin() const { |
| return Thunks.begin(); |
| } |
| |
| ThunksMapTy::const_iterator thunks_end() const { |
| return Thunks.end(); |
| } |
| |
| const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const { |
| return VBaseOffsetOffsets; |
| } |
| |
| const AddressPointsMapTy &getAddressPoints() const { |
| return AddressPoints; |
| } |
| |
| MethodVTableIndicesTy::const_iterator vtable_indices_begin() const { |
| return MethodVTableIndices.begin(); |
| } |
| |
| MethodVTableIndicesTy::const_iterator vtable_indices_end() const { |
| return MethodVTableIndices.end(); |
| } |
| |
| ArrayRef<VTableComponent> vtable_components() const { return Components; } |
| |
| AddressPointsMapTy::const_iterator address_points_begin() const { |
| return AddressPoints.begin(); |
| } |
| |
| AddressPointsMapTy::const_iterator address_points_end() const { |
| return AddressPoints.end(); |
| } |
| |
| VTableThunksMapTy::const_iterator vtable_thunks_begin() const { |
| return VTableThunks.begin(); |
| } |
| |
| VTableThunksMapTy::const_iterator vtable_thunks_end() const { |
| return VTableThunks.end(); |
| } |
| |
| /// dumpLayout - Dump the vtable layout. |
| void dumpLayout(raw_ostream&); |
| }; |
| |
| void ItaniumVTableBuilder::AddThunk(const CXXMethodDecl *MD, |
| const ThunkInfo &Thunk) { |
| assert(!isBuildingConstructorVTable() && |
| "Can't add thunks for construction vtable"); |
| |
| SmallVectorImpl<ThunkInfo> &ThunksVector = Thunks[MD]; |
| |
| // Check if we have this thunk already. |
| if (llvm::find(ThunksVector, Thunk) != ThunksVector.end()) |
| return; |
| |
| ThunksVector.push_back(Thunk); |
| } |
| |
| typedef llvm::SmallPtrSet<const CXXMethodDecl *, 8> OverriddenMethodsSetTy; |
| |
| /// Visit all the methods overridden by the given method recursively, |
| /// in a depth-first pre-order. The Visitor's visitor method returns a bool |
| /// indicating whether to continue the recursion for the given overridden |
| /// method (i.e. returning false stops the iteration). |
| template <class VisitorTy> |
| static void |
| visitAllOverriddenMethods(const CXXMethodDecl *MD, VisitorTy &Visitor) { |
| assert(MD->isVirtual() && "Method is not virtual!"); |
| |
| for (const CXXMethodDecl *OverriddenMD : MD->overridden_methods()) { |
| if (!Visitor(OverriddenMD)) |
| continue; |
| visitAllOverriddenMethods(OverriddenMD, Visitor); |
| } |
| } |
| |
| /// ComputeAllOverriddenMethods - Given a method decl, will return a set of all |
| /// the overridden methods that the function decl overrides. |
| static void |
| ComputeAllOverriddenMethods(const CXXMethodDecl *MD, |
| OverriddenMethodsSetTy& OverriddenMethods) { |
| auto OverriddenMethodsCollector = [&](const CXXMethodDecl *MD) { |
| // Don't recurse on this method if we've already collected it. |
| return OverriddenMethods.insert(MD).second; |
| }; |
| visitAllOverriddenMethods(MD, OverriddenMethodsCollector); |
| } |
| |
| void ItaniumVTableBuilder::ComputeThisAdjustments() { |
| // Now go through the method info map and see if any of the methods need |
| // 'this' pointer adjustments. |
| for (const auto &MI : MethodInfoMap) { |
| const CXXMethodDecl *MD = MI.first; |
| const MethodInfo &MethodInfo = MI.second; |
| |
| // Ignore adjustments for unused function pointers. |
| uint64_t VTableIndex = MethodInfo.VTableIndex; |
| if (Components[VTableIndex].getKind() == |
| VTableComponent::CK_UnusedFunctionPointer) |
| continue; |
| |
| // Get the final overrider for this method. |
| FinalOverriders::OverriderInfo Overrider = |
| Overriders.getOverrider(MD, MethodInfo.BaseOffset); |
| |
| // Check if we need an adjustment at all. |
| if (MethodInfo.BaseOffsetInLayoutClass == Overrider.Offset) { |
| // When a return thunk is needed by a derived class that overrides a |
| // virtual base, gcc uses a virtual 'this' adjustment as well. |
| // While the thunk itself might be needed by vtables in subclasses or |
| // in construction vtables, there doesn't seem to be a reason for using |
| // the thunk in this vtable. Still, we do so to match gcc. |
| if (VTableThunks.lookup(VTableIndex).Return.isEmpty()) |
| continue; |
| } |
| |
| ThisAdjustment ThisAdjustment = |
| ComputeThisAdjustment(MD, MethodInfo.BaseOffsetInLayoutClass, Overrider); |
| |
| if (ThisAdjustment.isEmpty()) |
| continue; |
| |
| // Add it. |
| VTableThunks[VTableIndex].This = ThisAdjustment; |
| |
| if (isa<CXXDestructorDecl>(MD)) { |
| // Add an adjustment for the deleting destructor as well. |
| VTableThunks[VTableIndex + 1].This = ThisAdjustment; |
| } |
| } |
| |
| /// Clear the method info map. |
| MethodInfoMap.clear(); |
| |
| if (isBuildingConstructorVTable()) { |
| // We don't need to store thunk information for construction vtables. |
| return; |
| } |
| |
| for (const auto &TI : VTableThunks) { |
| const VTableComponent &Component = Components[TI.first]; |
| const ThunkInfo &Thunk = TI.second; |
| const CXXMethodDecl *MD; |
| |
| switch (Component.getKind()) { |
| default: |
| llvm_unreachable("Unexpected vtable component kind!"); |
| case VTableComponent::CK_FunctionPointer: |
| MD = Component.getFunctionDecl(); |
| break; |
| case VTableComponent::CK_CompleteDtorPointer: |
| MD = Component.getDestructorDecl(); |
| break; |
| case VTableComponent::CK_DeletingDtorPointer: |
| // We've already added the thunk when we saw the complete dtor pointer. |
| continue; |
| } |
| |
| if (MD->getParent() == MostDerivedClass) |
| AddThunk(MD, Thunk); |
| } |
| } |
| |
| ReturnAdjustment |
| ItaniumVTableBuilder::ComputeReturnAdjustment(BaseOffset Offset) { |
| ReturnAdjustment Adjustment; |
| |
| if (!Offset.isEmpty()) { |
| if (Offset.VirtualBase) { |
| // Get the virtual base offset offset. |
| if (Offset.DerivedClass == MostDerivedClass) { |
| // We can get the offset offset directly from our map. |
| Adjustment.Virtual.Itanium.VBaseOffsetOffset = |
| VBaseOffsetOffsets.lookup(Offset.VirtualBase).getQuantity(); |
| } else { |
| Adjustment.Virtual.Itanium.VBaseOffsetOffset = |
| VTables.getVirtualBaseOffsetOffset(Offset.DerivedClass, |
| Offset.VirtualBase).getQuantity(); |
| } |
| } |
| |
| Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity(); |
| } |
| |
| return Adjustment; |
| } |
| |
| BaseOffset ItaniumVTableBuilder::ComputeThisAdjustmentBaseOffset( |
| BaseSubobject Base, BaseSubobject Derived) const { |
| const CXXRecordDecl *BaseRD = Base.getBase(); |
| const CXXRecordDecl *DerivedRD = Derived.getBase(); |
| |
| CXXBasePaths Paths(/*FindAmbiguities=*/true, |
| /*RecordPaths=*/true, /*DetectVirtual=*/true); |
| |
| if (!DerivedRD->isDerivedFrom(BaseRD, Paths)) |
| llvm_unreachable("Class must be derived from the passed in base class!"); |
| |
| // We have to go through all the paths, and see which one leads us to the |
| // right base subobject. |
| for (const CXXBasePath &Path : Paths) { |
| BaseOffset Offset = ComputeBaseOffset(Context, DerivedRD, Path); |
| |
| CharUnits OffsetToBaseSubobject = Offset.NonVirtualOffset; |
| |
| if (Offset.VirtualBase) { |
| // If we have a virtual base class, the non-virtual offset is relative |
| // to the virtual base class offset. |
| const ASTRecordLayout &LayoutClassLayout = |
| Context.getASTRecordLayout(LayoutClass); |
| |
| /// Get the virtual base offset, relative to the most derived class |
| /// layout. |
| OffsetToBaseSubobject += |
| LayoutClassLayout.getVBaseClassOffset(Offset.VirtualBase); |
| } else { |
| // Otherwise, the non-virtual offset is relative to the derived class |
| // offset. |
| OffsetToBaseSubobject += Derived.getBaseOffset(); |
| } |
| |
| // Check if this path gives us the right base subobject. |
| if (OffsetToBaseSubobject == Base.getBaseOffset()) { |
| // Since we're going from the base class _to_ the derived class, we'll |
| // invert the non-virtual offset here. |
| Offset.NonVirtualOffset = -Offset.NonVirtualOffset; |
| return Offset; |
| } |
| } |
| |
| return BaseOffset(); |
| } |
| |
| ThisAdjustment ItaniumVTableBuilder::ComputeThisAdjustment( |
| const CXXMethodDecl *MD, CharUnits BaseOffsetInLayoutClass, |
| FinalOverriders::OverriderInfo Overrider) { |
| // Ignore adjustments for pure virtual member functions. |
| if (Overrider.Method->isPure()) |
| return ThisAdjustment(); |
| |
| BaseSubobject OverriddenBaseSubobject(MD->getParent(), |
| BaseOffsetInLayoutClass); |
| |
| BaseSubobject OverriderBaseSubobject(Overrider.Method->getParent(), |
| Overrider.Offset); |
| |
| // Compute the adjustment offset. |
| BaseOffset Offset = ComputeThisAdjustmentBaseOffset(OverriddenBaseSubobject, |
| OverriderBaseSubobject); |
| if (Offset.isEmpty()) |
| return ThisAdjustment(); |
| |
| ThisAdjustment Adjustment; |
| |
| if (Offset.VirtualBase) { |
| // Get the vcall offset map for this virtual base. |
| VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Offset.VirtualBase]; |
| |
| if (VCallOffsets.empty()) { |
| // We don't have vcall offsets for this virtual base, go ahead and |
| // build them. |
| VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, MostDerivedClass, |
| /*Overriders=*/nullptr, |
| BaseSubobject(Offset.VirtualBase, |
| CharUnits::Zero()), |
| /*BaseIsVirtual=*/true, |
| /*OffsetInLayoutClass=*/ |
| CharUnits::Zero()); |
| |
| VCallOffsets = Builder.getVCallOffsets(); |
| } |
| |
| Adjustment.Virtual.Itanium.VCallOffsetOffset = |
| VCallOffsets.getVCallOffsetOffset(MD).getQuantity(); |
| } |
| |
| // Set the non-virtual part of the adjustment. |
| Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity(); |
| |
| return Adjustment; |
| } |
| |
| void ItaniumVTableBuilder::AddMethod(const CXXMethodDecl *MD, |
| ReturnAdjustment ReturnAdjustment) { |
| if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { |
| assert(ReturnAdjustment.isEmpty() && |
| "Destructor can't have return adjustment!"); |
| |
| // Add both the complete destructor and the deleting destructor. |
| Components.push_back(VTableComponent::MakeCompleteDtor(DD)); |
| Components.push_back(VTableComponent::MakeDeletingDtor(DD)); |
| } else { |
| // Add the return adjustment if necessary. |
| if (!ReturnAdjustment.isEmpty()) |
| VTableThunks[Components.size()].Return = ReturnAdjustment; |
| |
| // Add the function. |
| Components.push_back(VTableComponent::MakeFunction(MD)); |
| } |
| } |
| |
| /// OverridesIndirectMethodInBase - Return whether the given member function |
| /// overrides any methods in the set of given bases. |
| /// Unlike OverridesMethodInBase, this checks "overriders of overriders". |
| /// For example, if we have: |
| /// |
| /// struct A { virtual void f(); } |
| /// struct B : A { virtual void f(); } |
| /// struct C : B { virtual void f(); } |
| /// |
| /// OverridesIndirectMethodInBase will return true if given C::f as the method |
| /// and { A } as the set of bases. |
| static bool OverridesIndirectMethodInBases( |
| const CXXMethodDecl *MD, |
| ItaniumVTableBuilder::PrimaryBasesSetVectorTy &Bases) { |
| if (Bases.count(MD->getParent())) |
| return true; |
| |
| for (const CXXMethodDecl *OverriddenMD : MD->overridden_methods()) { |
| // Check "indirect overriders". |
| if (OverridesIndirectMethodInBases(OverriddenMD, Bases)) |
| return true; |
| } |
| |
| return false; |
| } |
| |
| bool ItaniumVTableBuilder::IsOverriderUsed( |
| const CXXMethodDecl *Overrider, CharUnits BaseOffsetInLayoutClass, |
| const CXXRecordDecl *FirstBaseInPrimaryBaseChain, |
| CharUnits FirstBaseOffsetInLayoutClass) const { |
| // If the base and the first base in the primary base chain have the same |
| // offsets, then this overrider will be used. |
| if (BaseOffsetInLayoutClass == FirstBaseOffsetInLayoutClass) |
| return true; |
| |
| // We know now that Base (or a direct or indirect base of it) is a primary |
| // base in part of the class hierarchy, but not a primary base in the most |
| // derived class. |
| |
| // If the overrider is the first base in the primary base chain, we know |
| // that the overrider will be used. |
| if (Overrider->getParent() == FirstBaseInPrimaryBaseChain) |
| return true; |
| |
| ItaniumVTableBuilder::PrimaryBasesSetVectorTy PrimaryBases; |
| |
| const CXXRecordDecl *RD = FirstBaseInPrimaryBaseChain; |
| PrimaryBases.insert(RD); |
| |
| // Now traverse the base chain, starting with the first base, until we find |
| // the base that is no longer a primary base. |
| while (true) { |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); |
| |
| if (!PrimaryBase) |
| break; |
| |
| if (Layout.isPrimaryBaseVirtual()) { |
| assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() && |
| "Primary base should always be at offset 0!"); |
| |
| const ASTRecordLayout &LayoutClassLayout = |
| Context.getASTRecordLayout(LayoutClass); |
| |
| // Now check if this is the primary base that is not a primary base in the |
| // most derived class. |
| if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) != |
| FirstBaseOffsetInLayoutClass) { |
| // We found it, stop walking the chain. |
| break; |
| } |
| } else { |
| assert(Layout.getBaseClassOffset(PrimaryBase).isZero() && |
| "Primary base should always be at offset 0!"); |
| } |
| |
| if (!PrimaryBases.insert(PrimaryBase)) |
| llvm_unreachable("Found a duplicate primary base!"); |
| |
| RD = PrimaryBase; |
| } |
| |
| // If the final overrider is an override of one of the primary bases, |
| // then we know that it will be used. |
| return OverridesIndirectMethodInBases(Overrider, PrimaryBases); |
| } |
| |
| typedef llvm::SmallSetVector<const CXXRecordDecl *, 8> BasesSetVectorTy; |
| |
| /// FindNearestOverriddenMethod - Given a method, returns the overridden method |
| /// from the nearest base. Returns null if no method was found. |
| /// The Bases are expected to be sorted in a base-to-derived order. |
| static const CXXMethodDecl * |
| FindNearestOverriddenMethod(const CXXMethodDecl *MD, |
| BasesSetVectorTy &Bases) { |
| OverriddenMethodsSetTy OverriddenMethods; |
| ComputeAllOverriddenMethods(MD, OverriddenMethods); |
| |
| for (const CXXRecordDecl *PrimaryBase : |
| llvm::make_range(Bases.rbegin(), Bases.rend())) { |
| // Now check the overridden methods. |
| for (const CXXMethodDecl *OverriddenMD : OverriddenMethods) { |
| // We found our overridden method. |
| if (OverriddenMD->getParent() == PrimaryBase) |
| return OverriddenMD; |
| } |
| } |
| |
| return nullptr; |
| } |
| |
| void ItaniumVTableBuilder::AddMethods( |
| BaseSubobject Base, CharUnits BaseOffsetInLayoutClass, |
| const CXXRecordDecl *FirstBaseInPrimaryBaseChain, |
| CharUnits FirstBaseOffsetInLayoutClass, |
| PrimaryBasesSetVectorTy &PrimaryBases) { |
| // Itanium C++ ABI 2.5.2: |
| // The order of the virtual function pointers in a virtual table is the |
| // order of declaration of the corresponding member functions in the class. |
| // |
| // There is an entry for any virtual function declared in a class, |
| // whether it is a new function or overrides a base class function, |
| // unless it overrides a function from the primary base, and conversion |
| // between their return types does not require an adjustment. |
| |
| const CXXRecordDecl *RD = Base.getBase(); |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| |
| if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) { |
| CharUnits PrimaryBaseOffset; |
| CharUnits PrimaryBaseOffsetInLayoutClass; |
| if (Layout.isPrimaryBaseVirtual()) { |
| assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() && |
| "Primary vbase should have a zero offset!"); |
| |
| const ASTRecordLayout &MostDerivedClassLayout = |
| Context.getASTRecordLayout(MostDerivedClass); |
| |
| PrimaryBaseOffset = |
| MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase); |
| |
| const ASTRecordLayout &LayoutClassLayout = |
| Context.getASTRecordLayout(LayoutClass); |
| |
| PrimaryBaseOffsetInLayoutClass = |
| LayoutClassLayout.getVBaseClassOffset(PrimaryBase); |
| } else { |
| assert(Layout.getBaseClassOffset(PrimaryBase).isZero() && |
| "Primary base should have a zero offset!"); |
| |
| PrimaryBaseOffset = Base.getBaseOffset(); |
| PrimaryBaseOffsetInLayoutClass = BaseOffsetInLayoutClass; |
| } |
| |
| AddMethods(BaseSubobject(PrimaryBase, PrimaryBaseOffset), |
| PrimaryBaseOffsetInLayoutClass, FirstBaseInPrimaryBaseChain, |
| FirstBaseOffsetInLayoutClass, PrimaryBases); |
| |
| if (!PrimaryBases.insert(PrimaryBase)) |
| llvm_unreachable("Found a duplicate primary base!"); |
| } |
| |
| const CXXDestructorDecl *ImplicitVirtualDtor = nullptr; |
| |
| typedef llvm::SmallVector<const CXXMethodDecl *, 8> NewVirtualFunctionsTy; |
| NewVirtualFunctionsTy NewVirtualFunctions; |
| |
| // Now go through all virtual member functions and add them. |
| for (const auto *MD : RD->methods()) { |
| if (!MD->isVirtual()) |
| continue; |
| MD = MD->getCanonicalDecl(); |
| |
| // Get the final overrider. |
| FinalOverriders::OverriderInfo Overrider = |
| Overriders.getOverrider(MD, Base.getBaseOffset()); |
| |
| // Check if this virtual member function overrides a method in a primary |
| // base. If this is the case, and the return type doesn't require adjustment |
| // then we can just use the member function from the primary base. |
| if (const CXXMethodDecl *OverriddenMD = |
| FindNearestOverriddenMethod(MD, PrimaryBases)) { |
| if (ComputeReturnAdjustmentBaseOffset(Context, MD, |
| OverriddenMD).isEmpty()) { |
| // Replace the method info of the overridden method with our own |
| // method. |
| assert(MethodInfoMap.count(OverriddenMD) && |
| "Did not find the overridden method!"); |
| MethodInfo &OverriddenMethodInfo = MethodInfoMap[OverriddenMD]; |
| |
| MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass, |
| OverriddenMethodInfo.VTableIndex); |
| |
| assert(!MethodInfoMap.count(MD) && |
| "Should not have method info for this method yet!"); |
| |
| MethodInfoMap.insert(std::make_pair(MD, MethodInfo)); |
| MethodInfoMap.erase(OverriddenMD); |
| |
| // If the overridden method exists in a virtual base class or a direct |
| // or indirect base class of a virtual base class, we need to emit a |
| // thunk if we ever have a class hierarchy where the base class is not |
| // a primary base in the complete object. |
| if (!isBuildingConstructorVTable() && OverriddenMD != MD) { |
| // Compute the this adjustment. |
| ThisAdjustment ThisAdjustment = |
| ComputeThisAdjustment(OverriddenMD, BaseOffsetInLayoutClass, |
| Overrider); |
| |
| if (ThisAdjustment.Virtual.Itanium.VCallOffsetOffset && |
| Overrider.Method->getParent() == MostDerivedClass) { |
| |
| // There's no return adjustment from OverriddenMD and MD, |
| // but that doesn't mean there isn't one between MD and |
| // the final overrider. |
| BaseOffset ReturnAdjustmentOffset = |
| ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD); |
| ReturnAdjustment ReturnAdjustment = |
| ComputeReturnAdjustment(ReturnAdjustmentOffset); |
| |
| // This is a virtual thunk for the most derived class, add it. |
| AddThunk(Overrider.Method, |
| ThunkInfo(ThisAdjustment, ReturnAdjustment)); |
| } |
| } |
| |
| continue; |
| } |
| } |
| |
| if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { |
| if (MD->isImplicit()) { |
| // Itanium C++ ABI 2.5.2: |
| // If a class has an implicitly-defined virtual destructor, |
| // its entries come after the declared virtual function pointers. |
| |
| assert(!ImplicitVirtualDtor && |
| "Did already see an implicit virtual dtor!"); |
| ImplicitVirtualDtor = DD; |
| continue; |
| } |
| } |
| |
| NewVirtualFunctions.push_back(MD); |
| } |
| |
| if (ImplicitVirtualDtor) |
| NewVirtualFunctions.push_back(ImplicitVirtualDtor); |
| |
| for (const CXXMethodDecl *MD : NewVirtualFunctions) { |
| // Get the final overrider. |
| FinalOverriders::OverriderInfo Overrider = |
| Overriders.getOverrider(MD, Base.getBaseOffset()); |
| |
| // Insert the method info for this method. |
| MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass, |
| Components.size()); |
| |
| assert(!MethodInfoMap.count(MD) && |
| "Should not have method info for this method yet!"); |
| MethodInfoMap.insert(std::make_pair(MD, MethodInfo)); |
| |
| // Check if this overrider is going to be used. |
| const CXXMethodDecl *OverriderMD = Overrider.Method; |
| if (!IsOverriderUsed(OverriderMD, BaseOffsetInLayoutClass, |
| FirstBaseInPrimaryBaseChain, |
| FirstBaseOffsetInLayoutClass)) { |
| Components.push_back(VTableComponent::MakeUnusedFunction(OverriderMD)); |
| continue; |
| } |
| |
| // Check if this overrider needs a return adjustment. |
| // We don't want to do this for pure virtual member functions. |
| BaseOffset ReturnAdjustmentOffset; |
| if (!OverriderMD->isPure()) { |
| ReturnAdjustmentOffset = |
| ComputeReturnAdjustmentBaseOffset(Context, OverriderMD, MD); |
| } |
| |
| ReturnAdjustment ReturnAdjustment = |
| ComputeReturnAdjustment(ReturnAdjustmentOffset); |
| |
| AddMethod(Overrider.Method, ReturnAdjustment); |
| } |
| } |
| |
| void ItaniumVTableBuilder::LayoutVTable() { |
| LayoutPrimaryAndSecondaryVTables(BaseSubobject(MostDerivedClass, |
| CharUnits::Zero()), |
| /*BaseIsMorallyVirtual=*/false, |
| MostDerivedClassIsVirtual, |
| MostDerivedClassOffset); |
| |
| VisitedVirtualBasesSetTy VBases; |
| |
| // Determine the primary virtual bases. |
| DeterminePrimaryVirtualBases(MostDerivedClass, MostDerivedClassOffset, |
| VBases); |
| VBases.clear(); |
| |
| LayoutVTablesForVirtualBases(MostDerivedClass, VBases); |
| |
| // -fapple-kext adds an extra entry at end of vtbl. |
| bool IsAppleKext = Context.getLangOpts().AppleKext; |
| if (IsAppleKext) |
| Components.push_back(VTableComponent::MakeVCallOffset(CharUnits::Zero())); |
| } |
| |
| void ItaniumVTableBuilder::LayoutPrimaryAndSecondaryVTables( |
| BaseSubobject Base, bool BaseIsMorallyVirtual, |
| bool BaseIsVirtualInLayoutClass, CharUnits OffsetInLayoutClass) { |
| assert(Base.getBase()->isDynamicClass() && "class does not have a vtable!"); |
| |
| unsigned VTableIndex = Components.size(); |
| VTableIndices.push_back(VTableIndex); |
| |
| // Add vcall and vbase offsets for this vtable. |
| VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, LayoutClass, &Overriders, |
| Base, BaseIsVirtualInLayoutClass, |
| OffsetInLayoutClass); |
| Components.append(Builder.components_begin(), Builder.components_end()); |
| |
| // Check if we need to add these vcall offsets. |
| if (BaseIsVirtualInLayoutClass && !Builder.getVCallOffsets().empty()) { |
| VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Base.getBase()]; |
| |
| if (VCallOffsets.empty()) |
| VCallOffsets = Builder.getVCallOffsets(); |
| } |
| |
| // If we're laying out the most derived class we want to keep track of the |
| // virtual base class offset offsets. |
| if (Base.getBase() == MostDerivedClass) |
| VBaseOffsetOffsets = Builder.getVBaseOffsetOffsets(); |
| |
| // Add the offset to top. |
| CharUnits OffsetToTop = MostDerivedClassOffset - OffsetInLayoutClass; |
| Components.push_back(VTableComponent::MakeOffsetToTop(OffsetToTop)); |
| |
| // Next, add the RTTI. |
| Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass)); |
| |
| uint64_t AddressPoint = Components.size(); |
| |
| // Now go through all virtual member functions and add them. |
| PrimaryBasesSetVectorTy PrimaryBases; |
| AddMethods(Base, OffsetInLayoutClass, |
| Base.getBase(), OffsetInLayoutClass, |
| PrimaryBases); |
| |
| const CXXRecordDecl *RD = Base.getBase(); |
| if (RD == MostDerivedClass) { |
| assert(MethodVTableIndices.empty()); |
| for (const auto &I : MethodInfoMap) { |
| const CXXMethodDecl *MD = I.first; |
| const MethodInfo &MI = I.second; |
| if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { |
| MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)] |
| = MI.VTableIndex - AddressPoint; |
| MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)] |
| = MI.VTableIndex + 1 - AddressPoint; |
| } else { |
| MethodVTableIndices[MD] = MI.VTableIndex - AddressPoint; |
| } |
| } |
| } |
| |
| // Compute 'this' pointer adjustments. |
| ComputeThisAdjustments(); |
| |
| // Add all address points. |
| while (true) { |
| AddressPoints.insert( |
| std::make_pair(BaseSubobject(RD, OffsetInLayoutClass), |
| VTableLayout::AddressPointLocation{ |
| unsigned(VTableIndices.size() - 1), |
| unsigned(AddressPoint - VTableIndex)})); |
| |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); |
| |
| if (!PrimaryBase) |
| break; |
| |
| if (Layout.isPrimaryBaseVirtual()) { |
| // Check if this virtual primary base is a primary base in the layout |
| // class. If it's not, we don't want to add it. |
| const ASTRecordLayout &LayoutClassLayout = |
| Context.getASTRecordLayout(LayoutClass); |
| |
| if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) != |
| OffsetInLayoutClass) { |
| // We don't want to add this class (or any of its primary bases). |
| break; |
| } |
| } |
| |
| RD = PrimaryBase; |
| } |
| |
| // Layout secondary vtables. |
| LayoutSecondaryVTables(Base, BaseIsMorallyVirtual, OffsetInLayoutClass); |
| } |
| |
| void |
| ItaniumVTableBuilder::LayoutSecondaryVTables(BaseSubobject Base, |
| bool BaseIsMorallyVirtual, |
| CharUnits OffsetInLayoutClass) { |
| // Itanium C++ ABI 2.5.2: |
| // Following the primary virtual table of a derived class are secondary |
| // virtual tables for each of its proper base classes, except any primary |
| // base(s) with which it shares its primary virtual table. |
| |
| const CXXRecordDecl *RD = Base.getBase(); |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); |
| |
| for (const auto &B : RD->bases()) { |
| // Ignore virtual bases, we'll emit them later. |
| if (B.isVirtual()) |
| continue; |
| |
| const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl(); |
| |
| // Ignore bases that don't have a vtable. |
| if (!BaseDecl->isDynamicClass()) |
| continue; |
| |
| if (isBuildingConstructorVTable()) { |
| // Itanium C++ ABI 2.6.4: |
| // Some of the base class subobjects may not need construction virtual |
| // tables, which will therefore not be present in the construction |
| // virtual table group, even though the subobject virtual tables are |
| // present in the main virtual table group for the complete object. |
| if (!BaseIsMorallyVirtual && !BaseDecl->getNumVBases()) |
| continue; |
| } |
| |
| // Get the base offset of this base. |
| CharUnits RelativeBaseOffset = Layout.getBaseClassOffset(BaseDecl); |
| CharUnits BaseOffset = Base.getBaseOffset() + RelativeBaseOffset; |
| |
| CharUnits BaseOffsetInLayoutClass = |
| OffsetInLayoutClass + RelativeBaseOffset; |
| |
| // Don't emit a secondary vtable for a primary base. We might however want |
| // to emit secondary vtables for other bases of this base. |
| if (BaseDecl == PrimaryBase) { |
| LayoutSecondaryVTables(BaseSubobject(BaseDecl, BaseOffset), |
| BaseIsMorallyVirtual, BaseOffsetInLayoutClass); |
| continue; |
| } |
| |
| // Layout the primary vtable (and any secondary vtables) for this base. |
| LayoutPrimaryAndSecondaryVTables( |
| BaseSubobject(BaseDecl, BaseOffset), |
| BaseIsMorallyVirtual, |
| /*BaseIsVirtualInLayoutClass=*/false, |
| BaseOffsetInLayoutClass); |
| } |
| } |
| |
| void ItaniumVTableBuilder::DeterminePrimaryVirtualBases( |
| const CXXRecordDecl *RD, CharUnits OffsetInLayoutClass, |
| VisitedVirtualBasesSetTy &VBases) { |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| |
| // Check if this base has a primary base. |
| if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) { |
| |
| // Check if it's virtual. |
| if (Layout.isPrimaryBaseVirtual()) { |
| bool IsPrimaryVirtualBase = true; |
| |
| if (isBuildingConstructorVTable()) { |
| // Check if the base is actually a primary base in the class we use for |
| // layout. |
| const ASTRecordLayout &LayoutClassLayout = |
| Context.getASTRecordLayout(LayoutClass); |
| |
| CharUnits PrimaryBaseOffsetInLayoutClass = |
| LayoutClassLayout.getVBaseClassOffset(PrimaryBase); |
| |
| // We know that the base is not a primary base in the layout class if |
| // the base offsets are different. |
| if (PrimaryBaseOffsetInLayoutClass != OffsetInLayoutClass) |
| IsPrimaryVirtualBase = false; |
| } |
| |
| if (IsPrimaryVirtualBase) |
| PrimaryVirtualBases.insert(PrimaryBase); |
| } |
| } |
| |
| // Traverse bases, looking for more primary virtual bases. |
| for (const auto &B : RD->bases()) { |
| const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl(); |
| |
| CharUnits BaseOffsetInLayoutClass; |
| |
| if (B.isVirtual()) { |
| if (!VBases.insert(BaseDecl).second) |
| continue; |
| |
| const ASTRecordLayout &LayoutClassLayout = |
| Context.getASTRecordLayout(LayoutClass); |
| |
| BaseOffsetInLayoutClass = |
| LayoutClassLayout.getVBaseClassOffset(BaseDecl); |
| } else { |
| BaseOffsetInLayoutClass = |
| OffsetInLayoutClass + Layout.getBaseClassOffset(BaseDecl); |
| } |
| |
| DeterminePrimaryVirtualBases(BaseDecl, BaseOffsetInLayoutClass, VBases); |
| } |
| } |
| |
| void ItaniumVTableBuilder::LayoutVTablesForVirtualBases( |
| const CXXRecordDecl *RD, VisitedVirtualBasesSetTy &VBases) { |
| // Itanium C++ ABI 2.5.2: |
| // Then come the virtual base virtual tables, also in inheritance graph |
| // order, and again excluding primary bases (which share virtual tables with |
| // the classes for which they are primary). |
| for (const auto &B : RD->bases()) { |
| const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl(); |
| |
| // Check if this base needs a vtable. (If it's virtual, not a primary base |
| // of some other class, and we haven't visited it before). |
| if (B.isVirtual() && BaseDecl->isDynamicClass() && |
| !PrimaryVirtualBases.count(BaseDecl) && |
| VBases.insert(BaseDecl).second) { |
| const ASTRecordLayout &MostDerivedClassLayout = |
| Context.getASTRecordLayout(MostDerivedClass); |
| CharUnits BaseOffset = |
| MostDerivedClassLayout.getVBaseClassOffset(BaseDecl); |
| |
| const ASTRecordLayout &LayoutClassLayout = |
| Context.getASTRecordLayout(LayoutClass); |
| CharUnits BaseOffsetInLayoutClass = |
| LayoutClassLayout.getVBaseClassOffset(BaseDecl); |
| |
| LayoutPrimaryAndSecondaryVTables( |
| BaseSubobject(BaseDecl, BaseOffset), |
| /*BaseIsMorallyVirtual=*/true, |
| /*BaseIsVirtualInLayoutClass=*/true, |
| BaseOffsetInLayoutClass); |
| } |
| |
| // We only need to check the base for virtual base vtables if it actually |
| // has virtual bases. |
| if (BaseDecl->getNumVBases()) |
| LayoutVTablesForVirtualBases(BaseDecl, VBases); |
| } |
| } |
| |
| /// dumpLayout - Dump the vtable layout. |
| void ItaniumVTableBuilder::dumpLayout(raw_ostream &Out) { |
| // FIXME: write more tests that actually use the dumpLayout output to prevent |
| // ItaniumVTableBuilder regressions. |
| |
| if (isBuildingConstructorVTable()) { |
| Out << "Construction vtable for ('"; |
| MostDerivedClass->printQualifiedName(Out); |
| Out << "', "; |
| Out << MostDerivedClassOffset.getQuantity() << ") in '"; |
| LayoutClass->printQualifiedName(Out); |
| } else { |
| Out << "Vtable for '"; |
| MostDerivedClass->printQualifiedName(Out); |
| } |
| Out << "' (" << Components.size() << " entries).\n"; |
| |
| // Iterate through the address points and insert them into a new map where |
| // they are keyed by the index and not the base object. |
| // Since an address point can be shared by multiple subobjects, we use an |
| // STL multimap. |
| std::multimap<uint64_t, BaseSubobject> AddressPointsByIndex; |
| for (const auto &AP : AddressPoints) { |
| const BaseSubobject &Base = AP.first; |
| uint64_t Index = |
| VTableIndices[AP.second.VTableIndex] + AP.second.AddressPointIndex; |
| |
| AddressPointsByIndex.insert(std::make_pair(Index, Base)); |
| } |
| |
| for (unsigned I = 0, E = Components.size(); I != E; ++I) { |
| uint64_t Index = I; |
| |
| Out << llvm::format("%4d | ", I); |
| |
| const VTableComponent &Component = Components[I]; |
| |
| // Dump the component. |
| switch (Component.getKind()) { |
| |
| case VTableComponent::CK_VCallOffset: |
| Out << "vcall_offset (" |
| << Component.getVCallOffset().getQuantity() |
| << ")"; |
| break; |
| |
| case VTableComponent::CK_VBaseOffset: |
| Out << "vbase_offset (" |
| << Component.getVBaseOffset().getQuantity() |
| << ")"; |
| break; |
| |
| case VTableComponent::CK_OffsetToTop: |
| Out << "offset_to_top (" |
| << Component.getOffsetToTop().getQuantity() |
| << ")"; |
| break; |
| |
| case VTableComponent::CK_RTTI: |
| Component.getRTTIDecl()->printQualifiedName(Out); |
| Out << " RTTI"; |
| break; |
| |
| case VTableComponent::CK_FunctionPointer: { |
| const CXXMethodDecl *MD = Component.getFunctionDecl(); |
| |
| std::string Str = |
| PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual, |
| MD); |
| Out << Str; |
| if (MD->isPure()) |
| Out << " [pure]"; |
| |
| if (MD->isDeleted()) |
| Out << " [deleted]"; |
| |
| ThunkInfo Thunk = VTableThunks.lookup(I); |
| if (!Thunk.isEmpty()) { |
| // If this function pointer has a return adjustment, dump it. |
| if (!Thunk.Return.isEmpty()) { |
| Out << "\n [return adjustment: "; |
| Out << Thunk.Return.NonVirtual << " non-virtual"; |
| |
| if (Thunk.Return.Virtual.Itanium.VBaseOffsetOffset) { |
| Out << ", " << Thunk.Return.Virtual.Itanium.VBaseOffsetOffset; |
| Out << " vbase offset offset"; |
| } |
| |
| Out << ']'; |
| } |
| |
| // If this function pointer has a 'this' pointer adjustment, dump it. |
| if (!Thunk.This.isEmpty()) { |
| Out << "\n [this adjustment: "; |
| Out << Thunk.This.NonVirtual << " non-virtual"; |
| |
| if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) { |
| Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset; |
| Out << " vcall offset offset"; |
| } |
| |
| Out << ']'; |
| } |
| } |
| |
| break; |
| } |
| |
| case VTableComponent::CK_CompleteDtorPointer: |
| case VTableComponent::CK_DeletingDtorPointer: { |
| bool IsComplete = |
| Component.getKind() == VTableComponent::CK_CompleteDtorPointer; |
| |
| const CXXDestructorDecl *DD = Component.getDestructorDecl(); |
| |
| DD->printQualifiedName(Out); |
| if (IsComplete) |
| Out << "() [complete]"; |
| else |
| Out << "() [deleting]"; |
| |
| if (DD->isPure()) |
| Out << " [pure]"; |
| |
| ThunkInfo Thunk = VTableThunks.lookup(I); |
| if (!Thunk.isEmpty()) { |
| // If this destructor has a 'this' pointer adjustment, dump it. |
| if (!Thunk.This.isEmpty()) { |
| Out << "\n [this adjustment: "; |
| Out << Thunk.This.NonVirtual << " non-virtual"; |
| |
| if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) { |
| Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset; |
| Out << " vcall offset offset"; |
| } |
| |
| Out << ']'; |
| } |
| } |
| |
| break; |
| } |
| |
| case VTableComponent::CK_UnusedFunctionPointer: { |
| const CXXMethodDecl *MD = Component.getUnusedFunctionDecl(); |
| |
| std::string Str = |
| PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual, |
| MD); |
| Out << "[unused] " << Str; |
| if (MD->isPure()) |
| Out << " [pure]"; |
| } |
| |
| } |
| |
| Out << '\n'; |
| |
| // Dump the next address point. |
| uint64_t NextIndex = Index + 1; |
| if (AddressPointsByIndex.count(NextIndex)) { |
| if (AddressPointsByIndex.count(NextIndex) == 1) { |
| const BaseSubobject &Base = |
| AddressPointsByIndex.find(NextIndex)->second; |
| |
| Out << " -- ("; |
| Base.getBase()->printQualifiedName(Out); |
| Out << ", " << Base.getBaseOffset().getQuantity(); |
| Out << ") vtable address --\n"; |
| } else { |
| CharUnits BaseOffset = |
| AddressPointsByIndex.lower_bound(NextIndex)->second.getBaseOffset(); |
| |
| // We store the class names in a set to get a stable order. |
| std::set<std::string> ClassNames; |
| for (const auto &I : |
| llvm::make_range(AddressPointsByIndex.equal_range(NextIndex))) { |
| assert(I.second.getBaseOffset() == BaseOffset && |
| "Invalid base offset!"); |
| const CXXRecordDecl *RD = I.second.getBase(); |
| ClassNames.insert(RD->getQualifiedNameAsString()); |
| } |
| |
| for (const std::string &Name : ClassNames) { |
| Out << " -- (" << Name; |
| Out << ", " << BaseOffset.getQuantity() << ") vtable address --\n"; |
| } |
| } |
| } |
| } |
| |
| Out << '\n'; |
| |
| if (isBuildingConstructorVTable()) |
| return; |
| |
| if (MostDerivedClass->getNumVBases()) { |
| // We store the virtual base class names and their offsets in a map to get |
| // a stable order. |
| |
| std::map<std::string, CharUnits> ClassNamesAndOffsets; |
| for (const auto &I : VBaseOffsetOffsets) { |
| std::string ClassName = I.first->getQualifiedNameAsString(); |
| CharUnits OffsetOffset = I.second; |
| ClassNamesAndOffsets.insert(std::make_pair(ClassName, OffsetOffset)); |
| } |
| |
| Out << "Virtual base offset offsets for '"; |
| MostDerivedClass->printQualifiedName(Out); |
| Out << "' ("; |
| Out << ClassNamesAndOffsets.size(); |
| Out << (ClassNamesAndOffsets.size() == 1 ? " entry" : " entries") << ").\n"; |
| |
| for (const auto &I : ClassNamesAndOffsets) |
| Out << " " << I.first << " | " << I.second.getQuantity() << '\n'; |
| |
| Out << "\n"; |
| } |
| |
| if (!Thunks.empty()) { |
| // We store the method names in a map to get a stable order. |
| std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls; |
| |
| for (const auto &I : Thunks) { |
| const CXXMethodDecl *MD = I.first; |
| std::string MethodName = |
| PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual, |
| MD); |
| |
| MethodNamesAndDecls.insert(std::make_pair(MethodName, MD)); |
| } |
| |
| for (const auto &I : MethodNamesAndDecls) { |
| const std::string &MethodName = I.first; |
| const CXXMethodDecl *MD = I.second; |
| |
| ThunkInfoVectorTy ThunksVector = Thunks[MD]; |
| llvm::sort(ThunksVector, [](const ThunkInfo &LHS, const ThunkInfo &RHS) { |
| assert(LHS.Method == nullptr && RHS.Method == nullptr); |
| return std::tie(LHS.This, LHS.Return) < std::tie(RHS.This, RHS.Return); |
| }); |
| |
| Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size(); |
| Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n"; |
| |
| for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) { |
| const ThunkInfo &Thunk = ThunksVector[I]; |
| |
| Out << llvm::format("%4d | ", I); |
| |
| // If this function pointer has a return pointer adjustment, dump it. |
| if (!Thunk.Return.isEmpty()) { |
| Out << "return adjustment: " << Thunk.Return.NonVirtual; |
| Out << " non-virtual"; |
| if (Thunk.Return.Virtual.Itanium.VBaseOffsetOffset) { |
| Out << ", " << Thunk.Return.Virtual.Itanium.VBaseOffsetOffset; |
| Out << " vbase offset offset"; |
| } |
| |
| if (!Thunk.This.isEmpty()) |
| Out << "\n "; |
| } |
| |
| // If this function pointer has a 'this' pointer adjustment, dump it. |
| if (!Thunk.This.isEmpty()) { |
| Out << "this adjustment: "; |
| Out << Thunk.This.NonVirtual << " non-virtual"; |
| |
| if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) { |
| Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset; |
| Out << " vcall offset offset"; |
| } |
| } |
| |
| Out << '\n'; |
| } |
| |
| Out << '\n'; |
| } |
| } |
| |
| // Compute the vtable indices for all the member functions. |
| // Store them in a map keyed by the index so we'll get a sorted table. |
| std::map<uint64_t, std::string> IndicesMap; |
| |
| for (const auto *MD : MostDerivedClass->methods()) { |
| // We only want virtual member functions. |
| if (!MD->isVirtual()) |
| continue; |
| MD = MD->getCanonicalDecl(); |
| |
| std::string MethodName = |
| PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual, |
| MD); |
| |
| if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { |
| GlobalDecl GD(DD, Dtor_Complete); |
| assert(MethodVTableIndices.count(GD)); |
| uint64_t VTableIndex = MethodVTableIndices[GD]; |
| IndicesMap[VTableIndex] = MethodName + " [complete]"; |
| IndicesMap[VTableIndex + 1] = MethodName + " [deleting]"; |
| } else { |
| assert(MethodVTableIndices.count(MD)); |
| IndicesMap[MethodVTableIndices[MD]] = MethodName; |
| } |
| } |
| |
| // Print the vtable indices for all the member functions. |
| if (!IndicesMap.empty()) { |
| Out << "VTable indices for '"; |
| MostDerivedClass->printQualifiedName(Out); |
| Out << "' (" << IndicesMap.size() << " entries).\n"; |
| |
| for (const auto &I : IndicesMap) { |
| uint64_t VTableIndex = I.first; |
| const std::string &MethodName = I.second; |
| |
| Out << llvm::format("%4" PRIu64 " | ", VTableIndex) << MethodName |
| << '\n'; |
| } |
| } |
| |
| Out << '\n'; |
| } |
| } |
| |
| VTableLayout::VTableLayout(ArrayRef<size_t> VTableIndices, |
| ArrayRef<VTableComponent> VTableComponents, |
| ArrayRef<VTableThunkTy> VTableThunks, |
| const AddressPointsMapTy &AddressPoints) |
| : VTableComponents(VTableComponents), VTableThunks(VTableThunks), |
| AddressPoints(AddressPoints) { |
| if (VTableIndices.size() <= 1) |
| assert(VTableIndices.size() == 1 && VTableIndices[0] == 0); |
| else |
| this->VTableIndices = OwningArrayRef<size_t>(VTableIndices); |
| |
| llvm::sort(this->VTableThunks, [](const VTableLayout::VTableThunkTy &LHS, |
| const VTableLayout::VTableThunkTy &RHS) { |
| assert((LHS.first != RHS.first || LHS.second == RHS.second) && |
| "Different thunks should have unique indices!"); |
| return LHS.first < RHS.first; |
| }); |
| } |
| |
| VTableLayout::~VTableLayout() { } |
| |
| ItaniumVTableContext::ItaniumVTableContext(ASTContext &Context) |
| : VTableContextBase(/*MS=*/false) {} |
| |
| ItaniumVTableContext::~ItaniumVTableContext() {} |
| |
| uint64_t ItaniumVTableContext::getMethodVTableIndex(GlobalDecl GD) { |
| GD = GD.getCanonicalDecl(); |
| MethodVTableIndicesTy::iterator I = MethodVTableIndices.find(GD); |
| if (I != MethodVTableIndices.end()) |
| return I->second; |
| |
| const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent(); |
| |
| computeVTableRelatedInformation(RD); |
| |
| I = MethodVTableIndices.find(GD); |
| assert(I != MethodVTableIndices.end() && "Did not find index!"); |
| return I->second; |
| } |
| |
| CharUnits |
| ItaniumVTableContext::getVirtualBaseOffsetOffset(const CXXRecordDecl *RD, |
| const CXXRecordDecl *VBase) { |
| ClassPairTy ClassPair(RD, VBase); |
| |
| VirtualBaseClassOffsetOffsetsMapTy::iterator I = |
| VirtualBaseClassOffsetOffsets.find(ClassPair); |
| if (I != VirtualBaseClassOffsetOffsets.end()) |
| return I->second; |
| |
| VCallAndVBaseOffsetBuilder Builder(RD, RD, /*Overriders=*/nullptr, |
| BaseSubobject(RD, CharUnits::Zero()), |
| /*BaseIsVirtual=*/false, |
| /*OffsetInLayoutClass=*/CharUnits::Zero()); |
| |
| for (const auto &I : Builder.getVBaseOffsetOffsets()) { |
| // Insert all types. |
| ClassPairTy ClassPair(RD, I.first); |
| |
| VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I.second)); |
| } |
| |
| I = VirtualBaseClassOffsetOffsets.find(ClassPair); |
| assert(I != VirtualBaseClassOffsetOffsets.end() && "Did not find index!"); |
| |
| return I->second; |
| } |
| |
| static std::unique_ptr<VTableLayout> |
| CreateVTableLayout(const ItaniumVTableBuilder &Builder) { |
| SmallVector<VTableLayout::VTableThunkTy, 1> |
| VTableThunks(Builder.vtable_thunks_begin(), Builder.vtable_thunks_end()); |
| |
| return std::make_unique<VTableLayout>( |
| Builder.VTableIndices, Builder.vtable_components(), VTableThunks, |
| Builder.getAddressPoints()); |
| } |
| |
| void |
| ItaniumVTableContext::computeVTableRelatedInformation(const CXXRecordDecl *RD) { |
| std::unique_ptr<const VTableLayout> &Entry = VTableLayouts[RD]; |
| |
| // Check if we've computed this information before. |
| if (Entry) |
| return; |
| |
| ItaniumVTableBuilder Builder(*this, RD, CharUnits::Zero(), |
| /*MostDerivedClassIsVirtual=*/0, RD); |
| Entry = CreateVTableLayout(Builder); |
| |
| MethodVTableIndices.insert(Builder.vtable_indices_begin(), |
| Builder.vtable_indices_end()); |
| |
| // Add the known thunks. |
| Thunks.insert(Builder.thunks_begin(), Builder.thunks_end()); |
| |
| // If we don't have the vbase information for this class, insert it. |
| // getVirtualBaseOffsetOffset will compute it separately without computing |
| // the rest of the vtable related information. |
| if (!RD->getNumVBases()) |
| return; |
| |
| const CXXRecordDecl *VBase = |
| RD->vbases_begin()->getType()->getAsCXXRecordDecl(); |
| |
| if (VirtualBaseClassOffsetOffsets.count(std::make_pair(RD, VBase))) |
| return; |
| |
| for (const auto &I : Builder.getVBaseOffsetOffsets()) { |
| // Insert all types. |
| ClassPairTy ClassPair(RD, I.first); |
| |
| VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I.second)); |
| } |
| } |
| |
| std::unique_ptr<VTableLayout> |
| ItaniumVTableContext::createConstructionVTableLayout( |
| const CXXRecordDecl *MostDerivedClass, CharUnits MostDerivedClassOffset, |
| bool MostDerivedClassIsVirtual, const CXXRecordDecl *LayoutClass) { |
| ItaniumVTableBuilder Builder(*this, MostDerivedClass, MostDerivedClassOffset, |
| MostDerivedClassIsVirtual, LayoutClass); |
| return CreateVTableLayout(Builder); |
| } |
| |
| namespace { |
| |
| // Vtables in the Microsoft ABI are different from the Itanium ABI. |
| // |
| // The main differences are: |
| // 1. Separate vftable and vbtable. |
| // |
| // 2. Each subobject with a vfptr gets its own vftable rather than an address |
| // point in a single vtable shared between all the subobjects. |
| // Each vftable is represented by a separate section and virtual calls |
| // must be done using the vftable which has a slot for the function to be |
| // called. |
| // |
| // 3. Virtual method definitions expect their 'this' parameter to point to the |
| // first vfptr whose table provides a compatible overridden method. In many |
| // cases, this permits the original vf-table entry to directly call |
| // the method instead of passing through a thunk. |
| // See example before VFTableBuilder::ComputeThisOffset below. |
| // |
| // A compatible overridden method is one which does not have a non-trivial |
| // covariant-return adjustment. |
| // |
| // The first vfptr is the one with the lowest offset in the complete-object |
| // layout of the defining class, and the method definition will subtract |
| // that constant offset from the parameter value to get the real 'this' |
| // value. Therefore, if the offset isn't really constant (e.g. if a virtual |
| // function defined in a virtual base is overridden in a more derived |
| // virtual base and these bases have a reverse order in the complete |
| // object), the vf-table may require a this-adjustment thunk. |
| // |
| // 4. vftables do not contain new entries for overrides that merely require |
| // this-adjustment. Together with #3, this keeps vf-tables smaller and |
| // eliminates the need for this-adjustment thunks in many cases, at the cost |
| // of often requiring redundant work to adjust the "this" pointer. |
| // |
| // 5. Instead of VTT and constructor vtables, vbtables and vtordisps are used. |
| // Vtordisps are emitted into the class layout if a class has |
| // a) a user-defined ctor/dtor |
| // and |
| // b) a method overriding a method in a virtual base. |
| // |
| // To get a better understanding of this code, |
| // you might want to see examples in test/CodeGenCXX/microsoft-abi-vtables-*.cpp |
| |
| class VFTableBuilder { |
| public: |
| typedef llvm::DenseMap<GlobalDecl, MethodVFTableLocation> |
| MethodVFTableLocationsTy; |
| |
| typedef llvm::iterator_range<MethodVFTableLocationsTy::const_iterator> |
| method_locations_range; |
| |
| private: |
| /// VTables - Global vtable information. |
| MicrosoftVTableContext &VTables; |
| |
| /// Context - The ASTContext which we will use for layout information. |
| ASTContext &Context; |
| |
| /// MostDerivedClass - The most derived class for which we're building this |
| /// vtable. |
| const CXXRecordDecl *MostDerivedClass; |
| |
| const ASTRecordLayout &MostDerivedClassLayout; |
| |
| const VPtrInfo &WhichVFPtr; |
| |
| /// FinalOverriders - The final overriders of the most derived class. |
| const FinalOverriders Overriders; |
| |
| /// Components - The components of the vftable being built. |
| SmallVector<VTableComponent, 64> Components; |
| |
| MethodVFTableLocationsTy MethodVFTableLocations; |
| |
| /// Does this class have an RTTI component? |
| bool HasRTTIComponent = false; |
| |
| /// MethodInfo - Contains information about a method in a vtable. |
| /// (Used for computing 'this' pointer adjustment thunks. |
| struct MethodInfo { |
| /// VBTableIndex - The nonzero index in the vbtable that |
| /// this method's base has, or zero. |
| const uint64_t VBTableIndex; |
| |
| /// VFTableIndex - The index in the vftable that this method has. |
| const uint64_t VFTableIndex; |
| |
| /// Shadowed - Indicates if this vftable slot is shadowed by |
| /// a slot for a covariant-return override. If so, it shouldn't be printed |
| /// or used for vcalls in the most derived class. |
| bool Shadowed; |
| |
| /// UsesExtraSlot - Indicates if this vftable slot was created because |
| /// any of the overridden slots required a return adjusting thunk. |
| bool UsesExtraSlot; |
| |
| MethodInfo(uint64_t VBTableIndex, uint64_t VFTableIndex, |
| bool UsesExtraSlot = false) |
| : VBTableIndex(VBTableIndex), VFTableIndex(VFTableIndex), |
| Shadowed(false), UsesExtraSlot(UsesExtraSlot) {} |
| |
| MethodInfo() |
| : VBTableIndex(0), VFTableIndex(0), Shadowed(false), |
| UsesExtraSlot(false) {} |
| }; |
| |
| typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy; |
| |
| /// MethodInfoMap - The information for all methods in the vftable we're |
| /// currently building. |
| MethodInfoMapTy MethodInfoMap; |
| |
| typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy; |
| |
| /// VTableThunks - The thunks by vftable index in the vftable currently being |
| /// built. |
| VTableThunksMapTy VTableThunks; |
| |
| typedef SmallVector<ThunkInfo, 1> ThunkInfoVectorTy; |
| typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy; |
| |
| /// Thunks - A map that contains all the thunks needed for all methods in the |
| /// most derived class for which the vftable is currently being built. |
| ThunksMapTy Thunks; |
| |
| /// AddThunk - Add a thunk for the given method. |
| void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk) { |
| SmallVector<ThunkInfo, 1> &ThunksVector = Thunks[MD]; |
| |
| // Check if we have this thunk already. |
| if (llvm::find(ThunksVector, Thunk) != ThunksVector.end()) |
| return; |
| |
| ThunksVector.push_back(Thunk); |
| } |
| |
| /// ComputeThisOffset - Returns the 'this' argument offset for the given |
| /// method, relative to the beginning of the MostDerivedClass. |
| CharUnits ComputeThisOffset(FinalOverriders::OverriderInfo Overrider); |
| |
| void CalculateVtordispAdjustment(FinalOverriders::OverriderInfo Overrider, |
| CharUnits ThisOffset, ThisAdjustment &TA); |
| |
| /// AddMethod - Add a single virtual member function to the vftable |
| /// components vector. |
| void AddMethod(const CXXMethodDecl *MD, ThunkInfo TI) { |
| if (!TI.isEmpty()) { |
| VTableThunks[Components.size()] = TI; |
| AddThunk(MD, TI); |
| } |
| if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { |
| assert(TI.Return.isEmpty() && |
| "Destructor can't have return adjustment!"); |
| Components.push_back(VTableComponent::MakeDeletingDtor(DD)); |
| } else { |
| Components.push_back(VTableComponent::MakeFunction(MD)); |
| } |
| } |
| |
| /// AddMethods - Add the methods of this base subobject and the relevant |
| /// subbases to the vftable we're currently laying out. |
| void AddMethods(BaseSubobject Base, unsigned BaseDepth, |
| const CXXRecordDecl *LastVBase, |
| BasesSetVectorTy &VisitedBases); |
| |
| void LayoutVFTable() { |
| // RTTI data goes before all other entries. |
| if (HasRTTIComponent) |
| Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass)); |
| |
| BasesSetVectorTy VisitedBases; |
| AddMethods(BaseSubobject(MostDerivedClass, CharUnits::Zero()), 0, nullptr, |
| VisitedBases); |
| assert((HasRTTIComponent ? Components.size() - 1 : Components.size()) && |
| "vftable can't be empty"); |
| |
| assert(MethodVFTableLocations.empty()); |
| for (const auto &I : MethodInfoMap) { |
| const CXXMethodDecl *MD = I.first; |
| const MethodInfo &MI = I.second; |
| assert(MD == MD->getCanonicalDecl()); |
| |
| // Skip the methods that the MostDerivedClass didn't override |
| // and the entries shadowed by return adjusting thunks. |
| if (MD->getParent() != MostDerivedClass || MI.Shadowed) |
| continue; |
| MethodVFTableLocation Loc(MI.VBTableIndex, WhichVFPtr.getVBaseWithVPtr(), |
| WhichVFPtr.NonVirtualOffset, MI.VFTableIndex); |
| if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { |
| MethodVFTableLocations[GlobalDecl(DD, Dtor_Deleting)] = Loc; |
| } else { |
| MethodVFTableLocations[MD] = Loc; |
| } |
| } |
| } |
| |
| public: |
| VFTableBuilder(MicrosoftVTableContext &VTables, |
| const CXXRecordDecl *MostDerivedClass, const VPtrInfo &Which) |
| : VTables(VTables), |
| Context(MostDerivedClass->getASTContext()), |
| MostDerivedClass(MostDerivedClass), |
| MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)), |
| WhichVFPtr(Which), |
| Overriders(MostDerivedClass, CharUnits(), MostDerivedClass) { |
| // Provide the RTTI component if RTTIData is enabled. If the vftable would |
| // be available externally, we should not provide the RTTI componenent. It |
| // is currently impossible to get available externally vftables with either |
| // dllimport or extern template instantiations, but eventually we may add a |
| // flag to support additional devirtualization that needs this. |
| if (Context.getLangOpts().RTTIData) |
| HasRTTIComponent = true; |
| |
| LayoutVFTable(); |
| |
| if (Context.getLangOpts().DumpVTableLayouts) |
| dumpLayout(llvm::outs()); |
| } |
| |
| uint64_t getNumThunks() const { return Thunks.size(); } |
| |
| ThunksMapTy::const_iterator thunks_begin() const { return Thunks.begin(); } |
| |
| ThunksMapTy::const_iterator thunks_end() const { return Thunks.end(); } |
| |
| method_locations_range vtable_locations() const { |
| return method_locations_range(MethodVFTableLocations.begin(), |
| MethodVFTableLocations.end()); |
| } |
| |
| ArrayRef<VTableComponent> vtable_components() const { return Components; } |
| |
| VTableThunksMapTy::const_iterator vtable_thunks_begin() const { |
| return VTableThunks.begin(); |
| } |
| |
| VTableThunksMapTy::const_iterator vtable_thunks_end() const { |
| return VTableThunks.end(); |
| } |
| |
| void dumpLayout(raw_ostream &); |
| }; |
| |
| } // end namespace |
| |
| // Let's study one class hierarchy as an example: |
| // struct A { |
| // virtual void f(); |
| // int x; |
| // }; |
| // |
| // struct B : virtual A { |
| // virtual void f(); |
| // }; |
| // |
| // Record layouts: |
| // struct A: |
| // 0 | (A vftable pointer) |
| // 4 | int x |
| // |
| // struct B: |
| // 0 | (B vbtable pointer) |
| // 4 | struct A (virtual base) |
| // 4 | (A vftable pointer) |
| // 8 | int x |
| // |
| // Let's assume we have a pointer to the A part of an object of dynamic type B: |
| // B b; |
| // A *a = (A*)&b; |
| // a->f(); |
| // |
| // In this hierarchy, f() belongs to the vftable of A, so B::f() expects |
| // "this" parameter to point at the A subobject, which is B+4. |
| // In the B::f() prologue, it adjusts "this" back to B by subtracting 4, |
| // performed as a *static* adjustment. |
| // |
| // Interesting thing happens when we alter the relative placement of A and B |
| // subobjects in a class: |
| // struct C : virtual B { }; |
| // |
| // C c; |
| // A *a = (A*)&c; |
| // a->f(); |
| // |
| // Respective record layout is: |
| // 0 | (C vbtable pointer) |
| // 4 | struct A (virtual base) |
| // 4 | (A vftable pointer) |
| // 8 | int x |
| // 12 | struct B (virtual base) |
| // 12 | (B vbtable pointer) |
| // |
| // The final overrider of f() in class C is still B::f(), so B+4 should be |
| // passed as "this" to that code. However, "a" points at B-8, so the respective |
| // vftable entry should hold a thunk that adds 12 to the "this" argument before |
| // performing a tail call to B::f(). |
| // |
| // With this example in mind, we can now calculate the 'this' argument offset |
| // for the given method, relative to the beginning of the MostDerivedClass. |
| CharUnits |
| VFTableBuilder::ComputeThisOffset(FinalOverriders::OverriderInfo Overrider) { |
| BasesSetVectorTy Bases; |
| |
| { |
| // Find the set of least derived bases that define the given method. |
| OverriddenMethodsSetTy VisitedOverriddenMethods; |
| auto InitialOverriddenDefinitionCollector = [&]( |
| const CXXMethodDecl *OverriddenMD) { |
| if (OverriddenMD->size_overridden_methods() == 0) |
| Bases.insert(OverriddenMD->getParent()); |
| // Don't recurse on this method if we've already collected it. |
| return VisitedOverriddenMethods.insert(OverriddenMD).second; |
| }; |
| visitAllOverriddenMethods(Overrider.Method, |
| InitialOverriddenDefinitionCollector); |
| } |
| |
| // If there are no overrides then 'this' is located |
| // in the base that defines the method. |
| if (Bases.size() == 0) |
| return Overrider.Offset; |
| |
| CXXBasePaths Paths; |
| Overrider.Method->getParent()->lookupInBases( |
| [&Bases](const CXXBaseSpecifier *Specifier, CXXBasePath &) { |
| return Bases.count(Specifier->getType()->getAsCXXRecordDecl()); |
| }, |
| Paths); |
| |
| // This will hold the smallest this offset among overridees of MD. |
| // This implies that an offset of a non-virtual base will dominate an offset |
| // of a virtual base to potentially reduce the number of thunks required |
| // in the derived classes that inherit this method. |
| CharUnits Ret; |
| bool First = true; |
| |
| const ASTRecordLayout &OverriderRDLayout = |
| Context.getASTRecordLayout(Overrider.Method->getParent()); |
| for (const CXXBasePath &Path : Paths) { |
| CharUnits ThisOffset = Overrider.Offset; |
| CharUnits LastVBaseOffset; |
| |
| // For each path from the overrider to the parents of the overridden |
| // methods, traverse the path, calculating the this offset in the most |
| // derived class. |
| for (const CXXBasePathElement &Element : Path) { |
| QualType CurTy = Element.Base->getType(); |
| const CXXRecordDecl *PrevRD = Element.Class, |
| *CurRD = CurTy->getAsCXXRecordDecl(); |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(PrevRD); |
| |
| if (Element.Base->isVirtual()) { |
| // The interesting things begin when you have virtual inheritance. |
| // The final overrider will use a static adjustment equal to the offset |
| // of the vbase in the final overrider class. |
| // For example, if the final overrider is in a vbase B of the most |
| // derived class and it overrides a method of the B's own vbase A, |
| // it uses A* as "this". In its prologue, it can cast A* to B* with |
| // a static offset. This offset is used regardless of the actual |
| // offset of A from B in the most derived class, requiring an |
| // this-adjusting thunk in the vftable if A and B are laid out |
| // differently in the most derived class. |
| LastVBaseOffset = ThisOffset = |
| Overrider.Offset + OverriderRDLayout.getVBaseClassOffset(CurRD); |
| } else { |
| ThisOffset += Layout.getBaseClassOffset(CurRD); |
| } |
| } |
| |
| if (isa<CXXDestructorDecl>(Overrider.Method)) { |
| if (LastVBaseOffset.isZero()) { |
| // If a "Base" class has at least one non-virtual base with a virtual |
| // destructor, the "Base" virtual destructor will take the address |
| // of the "Base" subobject as the "this" argument. |
| ThisOffset = Overrider.Offset; |
| } else { |
| // A virtual destructor of a virtual base takes the address of the |
| // virtual base subobject as the "this" argument. |
| ThisOffset = LastVBaseOffset; |
| } |
| } |
| |
| if (Ret > ThisOffset || First) { |
| First = false; |
| Ret = ThisOffset; |
| } |
| } |
| |
| assert(!First && "Method not found in the given subobject?"); |
| return Ret; |
| } |
| |
| // Things are getting even more complex when the "this" adjustment has to |
| // use a dynamic offset instead of a static one, or even two dynamic offsets. |
| // This is sometimes required when a virtual call happens in the middle of |
| // a non-most-derived class construction or destruction. |
| // |
| // Let's take a look at the following example: |
| // struct A { |
| // virtual void f(); |
| // }; |
| // |
| // void foo(A *a) { a->f(); } // Knows nothing about siblings of A. |
| // |
| // struct B : virtual A { |
| // virtual void f(); |
| // B() { |
| // foo(this); |
| // } |
| // }; |
| // |
| // struct C : virtual B { |
| // virtual void f(); |
| // }; |
| // |
| // Record layouts for these classes are: |
| // struct A |
| // 0 | (A vftable pointer) |
| // |
| // struct B |
| // 0 | (B vbtable pointer) |
| // 4 | (vtordisp for vbase A) |
| // 8 | struct A (virtual base) |
| // 8 | (A vftable pointer) |
| // |
| // struct C |
| // 0 | (C vbtable pointer) |
| // 4 | (vtordisp for vbase A) |
| // 8 | struct A (virtual base) // A precedes B! |
| // 8 | (A vftable pointer) |
| // 12 | struct B (virtual base) |
| // 12 | (B vbtable pointer) |
| // |
| // When one creates an object of type C, the C constructor: |
| // - initializes all the vbptrs, then |
| // - calls the A subobject constructor |
| // (initializes A's vfptr with an address of A vftable), then |
| // - calls the B subobject constructor |
| // (initializes A's vfptr with an address of B vftable and vtordisp for A), |
| // that in turn calls foo(), then |
| // - initializes A's vfptr with an address of C vftable and zeroes out the |
| // vtordisp |
| // FIXME: if a structor knows it belongs to MDC, why doesn't it use a vftable |
| // without vtordisp thunks? |
| // FIXME: how are vtordisp handled in the presence of nooverride/final? |
| // |
| // When foo() is called, an object with a layout of class C has a vftable |
| // referencing B::f() that assumes a B layout, so the "this" adjustments are |
| // incorrect, unless an extra adjustment is done. This adjustment is called |
| // "vtordisp adjustment". Vtordisp basically holds the difference between the |
| // actual location of a vbase in the layout class and the location assumed by |
| // the vftable of the class being constructed/destructed. Vtordisp is only |
| // needed if "this" escapes a |
| // structor (or we can't prove otherwise). |
| // [i.e. vtordisp is a dynamic adjustment for a static adjustment, which is an |
| // estimation of a dynamic adjustment] |
| // |
| // foo() gets a pointer to the A vbase and doesn't know anything about B or C, |
| // so it just passes that pointer as "this" in a virtual call. |
| // If there was no vtordisp, that would just dispatch to B::f(). |
| // However, B::f() assumes B+8 is passed as "this", |
| // yet the pointer foo() passes along is B-4 (i.e. C+8). |
| // An extra adjustment is needed, so we emit a thunk into the B vftable. |
| // This vtordisp thunk subtracts the value of vtordisp |
| // from the "this" argument (-12) before making a tailcall to B::f(). |
| // |
| // Let's consider an even more complex example: |
| // struct D : virtual B, virtual C { |
| // D() { |
| // foo(this); |
| // } |
| // }; |
| // |
| // struct D |
| // 0 | (D vbtable pointer) |
| // 4 | (vtordisp for vbase A) |
| // 8 | struct A (virtual base) // A precedes both B and C! |
| // 8 | (A vftable pointer) |
| // 12 | struct B (virtual base) // B precedes C! |
| // 12 | (B vbtable pointer) |
| // 16 | struct C (virtual base) |
| // 16 | (C vbtable pointer) |
| // |
| // When D::D() calls foo(), we find ourselves in a thunk that should tailcall |
| // to C::f(), which assumes C+8 as its "this" parameter. This time, foo() |
| // passes along A, which is C-8. The A vtordisp holds |
| // "D.vbptr[index_of_A] - offset_of_A_in_D" |
| // and we statically know offset_of_A_in_D, so can get a pointer to D. |
| // When we know it, we can make an extra vbtable lookup to locate the C vbase |
| // and one extra static adjustment to calculate the expected value of C+8. |
| void VFTableBuilder::CalculateVtordispAdjustment( |
| FinalOverriders::OverriderInfo Overrider, CharUnits ThisOffset, |
| ThisAdjustment &TA) { |
| const ASTRecordLayout::VBaseOffsetsMapTy &VBaseMap = |
| MostDerivedClassLayout.getVBaseOffsetsMap(); |
| const ASTRecordLayout::VBaseOffsetsMapTy::const_iterator &VBaseMapEntry = |
| VBaseMap.find(WhichVFPtr.getVBaseWithVPtr()); |
| assert(VBaseMapEntry != VBaseMap.end()); |
| |
| // If there's no vtordisp or the final overrider is defined in the same vbase |
| // as the initial declaration, we don't need any vtordisp adjustment. |
| if (!VBaseMapEntry->second.hasVtorDisp() || |
| Overrider.VirtualBase == WhichVFPtr.getVBaseWithVPtr()) |
| return; |
| |
| // OK, now we know we need to use a vtordisp thunk. |
| // The implicit vtordisp field is located right before the vbase. |
| CharUnits OffsetOfVBaseWithVFPtr = VBaseMapEntry->second.VBaseOffset; |
| TA.Virtual.Microsoft.VtordispOffset = |
| (OffsetOfVBaseWithVFPtr - WhichVFPtr.FullOffsetInMDC).getQuantity() - 4; |
| |
| // A simple vtordisp thunk will suffice if the final overrider is defined |
| // in either the most derived class or its non-virtual base. |
| if (Overrider.Method->getParent() == MostDerivedClass || |
| !Overrider.VirtualBase) |
| return; |
| |
| // Otherwise, we need to do use the dynamic offset of the final overrider |
| // in order to get "this" adjustment right. |
| TA.Virtual.Microsoft.VBPtrOffset = |
| (OffsetOfVBaseWithVFPtr + WhichVFPtr.NonVirtualOffset - |
| MostDerivedClassLayout.getVBPtrOffset()).getQuantity(); |
| TA.Virtual.Microsoft.VBOffsetOffset = |
| Context.getTypeSizeInChars(Context.IntTy).getQuantity() * |
| VTables.getVBTableIndex(MostDerivedClass, Overrider.VirtualBase); |
| |
| TA.NonVirtual = (ThisOffset - Overrider.Offset).getQuantity(); |
| } |
| |
| static void GroupNewVirtualOverloads( |
| const CXXRecordDecl *RD, |
| SmallVector<const CXXMethodDecl *, 10> &VirtualMethods) { |
| // Put the virtual methods into VirtualMethods in the proper order: |
| // 1) Group overloads by declaration name. New groups are added to the |
| // vftable in the order of their first declarations in this class |
| // (including overrides, non-virtual methods and any other named decl that |
| // might be nested within the class). |
| // 2) In each group, new overloads appear in the reverse order of declaration. |
| typedef SmallVector<const CXXMethodDecl *, 1> MethodGroup; |
| SmallVector<MethodGroup, 10> Groups; |
| typedef llvm::DenseMap<DeclarationName, unsigned> VisitedGroupIndicesTy; |
| VisitedGroupIndicesTy VisitedGroupIndices; |
| for (const auto *D : RD->decls()) { |
| const auto *ND = dyn_cast<NamedDecl>(D); |
| if (!ND) |
| continue; |
| VisitedGroupIndicesTy::iterator J; |
| bool Inserted; |
| std::tie(J, Inserted) = VisitedGroupIndices.insert( |
| std::make_pair(ND->getDeclName(), Groups.size())); |
| if (Inserted) |
| Groups.push_back(MethodGroup()); |
| if (const auto *MD = dyn_cast<CXXMethodDecl>(ND)) |
| if (MD->isVirtual()) |
| Groups[J->second].push_back(MD->getCanonicalDecl()); |
| } |
| |
| for (const MethodGroup &Group : Groups) |
| VirtualMethods.append(Group.rbegin(), Group.rend()); |
| } |
| |
| static bool isDirectVBase(const CXXRecordDecl *Base, const CXXRecordDecl *RD) { |
| for (const auto &B : RD->bases()) { |
| if (B.isVirtual() && B.getType()->getAsCXXRecordDecl() == Base) |
| return true; |
| } |
| return false; |
| } |
| |
| void VFTableBuilder::AddMethods(BaseSubobject Base, unsigned BaseDepth, |
| const CXXRecordDecl *LastVBase, |
| BasesSetVectorTy &VisitedBases) { |
| const CXXRecordDecl *RD = Base.getBase(); |
| if (!RD->isPolymorphic()) |
| return; |
| |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| |
| // See if this class expands a vftable of the base we look at, which is either |
| // the one defined by the vfptr base path or the primary base of the current |
| // class. |
| const CXXRecordDecl *NextBase = nullptr, *NextLastVBase = LastVBase; |
| CharUnits NextBaseOffset; |
| if (BaseDepth < WhichVFPtr.PathToIntroducingObject.size()) { |
| NextBase = WhichVFPtr.PathToIntroducingObject[BaseDepth]; |
| if (isDirectVBase(NextBase, RD)) { |
| NextLastVBase = NextBase; |
| NextBaseOffset = MostDerivedClassLayout.getVBaseClassOffset(NextBase); |
| } else { |
| NextBaseOffset = |
| Base.getBaseOffset() + Layout.getBaseClassOffset(NextBase); |
| } |
| } else if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) { |
| assert(!Layout.isPrimaryBaseVirtual() && |
| "No primary virtual bases in this ABI"); |
| NextBase = PrimaryBase; |
| NextBaseOffset = Base.getBaseOffset(); |
| } |
| |
| if (NextBase) { |
| AddMethods(BaseSubobject(NextBase, NextBaseOffset), BaseDepth + 1, |
| NextLastVBase, VisitedBases); |
| if (!VisitedBases.insert(NextBase)) |
| llvm_unreachable("Found a duplicate primary base!"); |
| } |
| |
| SmallVector<const CXXMethodDecl*, 10> VirtualMethods; |
| // Put virtual methods in the proper order. |
| GroupNewVirtualOverloads(RD, VirtualMethods); |
| |
| // Now go through all virtual member functions and add them to the current |
| // vftable. This is done by |
| // - replacing overridden methods in their existing slots, as long as they |
| // don't require return adjustment; calculating This adjustment if needed. |
| // - adding new slots for methods of the current base not present in any |
| // sub-bases; |
| // - adding new slots for methods that require Return adjustment. |
| // We keep track of the methods visited in the sub-bases in MethodInfoMap. |
| |