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Diffstat (limited to 'lib/CodeGen/CGVTables.cpp')
| -rw-r--r-- | lib/CodeGen/CGVTables.cpp | 3167 |
1 files changed, 3167 insertions, 0 deletions
diff --git a/lib/CodeGen/CGVTables.cpp b/lib/CodeGen/CGVTables.cpp new file mode 100644 index 000000000000..159753aa359c --- /dev/null +++ b/lib/CodeGen/CGVTables.cpp @@ -0,0 +1,3167 @@ +//===--- CGVTables.cpp - Emit LLVM Code for C++ vtables -------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This contains code dealing with C++ code generation of virtual tables. +// +//===----------------------------------------------------------------------===// + +#include "CodeGenModule.h" +#include "CodeGenFunction.h" +#include "clang/AST/CXXInheritance.h" +#include "clang/AST/RecordLayout.h" +#include "llvm/ADT/DenseSet.h" +#include "llvm/ADT/SetVector.h" +#include "llvm/Support/Compiler.h" +#include "llvm/Support/Format.h" +#include <algorithm> +#include <cstdio> + +using namespace clang; +using namespace CodeGen; + +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 a virtual base class, this holds its declaration. + 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. + int64_t NonVirtualOffset; + + BaseOffset() : DerivedClass(0), VirtualBase(0), NonVirtualOffset(0) { } + BaseOffset(const CXXRecordDecl *DerivedClass, + const CXXRecordDecl *VirtualBase, int64_t NonVirtualOffset) + : DerivedClass(DerivedClass), VirtualBase(VirtualBase), + NonVirtualOffset(NonVirtualOffset) { } + + bool isEmpty() const { return !NonVirtualOffset && !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; + + /// Offset - the base offset of the overrider in the layout class. + uint64_t Offset; + + OverriderInfo() : Method(0), Offset(0) { } + }; + +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 uint64_t 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; + + /// BaseSubobjectMethodPairTy - Uniquely identifies a member function + /// in a base subobject. + typedef std::pair<BaseSubobject, const CXXMethodDecl *> + BaseSubobjectMethodPairTy; + + typedef llvm::DenseMap<BaseSubobjectMethodPairTy, + OverriderInfo> OverridersMapTy; + + /// OverridersMap - The final overriders for all virtual member functions of + /// all the base subobjects of the most derived class. + OverridersMapTy OverridersMap; + + /// VisitedVirtualBases - A set of all the visited virtual bases, used to + /// avoid visiting virtual bases more than once. + llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases; + + typedef llvm::DenseMap<BaseSubobjectMethodPairTy, BaseOffset> + AdjustmentOffsetsMapTy; + + /// ReturnAdjustments - Holds return adjustments for all the overriders that + /// need to perform return value adjustments. + AdjustmentOffsetsMapTy ReturnAdjustments; + + // FIXME: We might be able to get away with making this a SmallSet. + typedef llvm::SmallSetVector<uint64_t, 2> OffsetSetVectorTy; + + /// SubobjectOffsetsMapTy - This map is used for keeping track of all the + /// base subobject offsets that a single class declaration might refer to. + /// + /// For example, in: + /// + /// struct A { virtual void f(); }; + /// struct B1 : A { }; + /// struct B2 : A { }; + /// struct C : B1, B2 { virtual void f(); }; + /// + /// when we determine that C::f() overrides A::f(), we need to update the + /// overriders map for both A-in-B1 and A-in-B2 and the subobject offsets map + /// will have the subobject offsets for both A copies. + typedef llvm::DenseMap<const CXXRecordDecl *, OffsetSetVectorTy> + SubobjectOffsetsMapTy; + + /// ComputeFinalOverriders - Compute the final overriders for a given base + /// subobject (and all its direct and indirect bases). + void ComputeFinalOverriders(BaseSubobject Base, + bool BaseSubobjectIsVisitedVBase, + uint64_t OffsetInLayoutClass, + SubobjectOffsetsMapTy &Offsets); + + /// AddOverriders - Add the final overriders for this base subobject to the + /// map of final overriders. + void AddOverriders(BaseSubobject Base, uint64_t OffsetInLayoutClass, + SubobjectOffsetsMapTy &Offsets); + + /// PropagateOverrider - Propagate the NewMD overrider to all the functions + /// that OldMD overrides. For example, if we have: + /// + /// struct A { virtual void f(); }; + /// struct B : A { virtual void f(); }; + /// struct C : B { virtual void f(); }; + /// + /// and we want to override B::f with C::f, we also need to override A::f with + /// C::f. + void PropagateOverrider(const CXXMethodDecl *OldMD, + BaseSubobject NewBase, + uint64_t OverriderOffsetInLayoutClass, + const CXXMethodDecl *NewMD, + SubobjectOffsetsMapTy &Offsets); + + static void MergeSubobjectOffsets(const SubobjectOffsetsMapTy &NewOffsets, + SubobjectOffsetsMapTy &Offsets); + +public: + FinalOverriders(const CXXRecordDecl *MostDerivedClass, + uint64_t MostDerivedClassOffset, + const CXXRecordDecl *LayoutClass); + + /// getOverrider - Get the final overrider for the given method declaration in + /// the given base subobject. + OverriderInfo getOverrider(BaseSubobject Base, + const CXXMethodDecl *MD) const { + assert(OverridersMap.count(std::make_pair(Base, MD)) && + "Did not find overrider!"); + + return OverridersMap.lookup(std::make_pair(Base, MD)); + } + + /// getReturnAdjustmentOffset - Get the return adjustment offset for the + /// method decl in the given base subobject. Returns an empty base offset if + /// no adjustment is needed. + BaseOffset getReturnAdjustmentOffset(BaseSubobject Base, + const CXXMethodDecl *MD) const { + return ReturnAdjustments.lookup(std::make_pair(Base, MD)); + } + + /// dump - dump the final overriders. + void dump() { + assert(VisitedVirtualBases.empty() && + "Visited virtual bases aren't empty!"); + dump(llvm::errs(), BaseSubobject(MostDerivedClass, 0)); + VisitedVirtualBases.clear(); + } + + /// dump - dump the final overriders for a base subobject, and all its direct + /// and indirect base subobjects. + void dump(llvm::raw_ostream &Out, BaseSubobject Base); +}; + +#define DUMP_OVERRIDERS 0 + +FinalOverriders::FinalOverriders(const CXXRecordDecl *MostDerivedClass, + uint64_t MostDerivedClassOffset, + const CXXRecordDecl *LayoutClass) + : MostDerivedClass(MostDerivedClass), + MostDerivedClassOffset(MostDerivedClassOffset), LayoutClass(LayoutClass), + Context(MostDerivedClass->getASTContext()), + MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)) { + + // Compute the final overriders. + SubobjectOffsetsMapTy Offsets; + ComputeFinalOverriders(BaseSubobject(MostDerivedClass, 0), + /*BaseSubobjectIsVisitedVBase=*/false, + MostDerivedClassOffset, Offsets); + VisitedVirtualBases.clear(); + +#if DUMP_OVERRIDERS + // And dump them (for now). + dump(); + + // Also dump the base offsets (for now). + for (SubobjectOffsetsMapTy::const_iterator I = Offsets.begin(), + E = Offsets.end(); I != E; ++I) { + const OffsetSetVectorTy& OffsetSetVector = I->second; + + llvm::errs() << "Base offsets for "; + llvm::errs() << I->first->getQualifiedNameAsString() << '\n'; + + for (unsigned I = 0, E = OffsetSetVector.size(); I != E; ++I) + llvm::errs() << " " << I << " - " << OffsetSetVector[I] / 8 << '\n'; + } +#endif +} + +void FinalOverriders::AddOverriders(BaseSubobject Base, + uint64_t OffsetInLayoutClass, + SubobjectOffsetsMapTy &Offsets) { + const CXXRecordDecl *RD = Base.getBase(); + + for (CXXRecordDecl::method_iterator I = RD->method_begin(), + E = RD->method_end(); I != E; ++I) { + const CXXMethodDecl *MD = *I; + + if (!MD->isVirtual()) + continue; + + // First, propagate the overrider. + PropagateOverrider(MD, Base, OffsetInLayoutClass, MD, Offsets); + + // Add the overrider as the final overrider of itself. + OverriderInfo& Overrider = OverridersMap[std::make_pair(Base, MD)]; + assert(!Overrider.Method && "Overrider should not exist yet!"); + + Overrider.Offset = OffsetInLayoutClass; + Overrider.Method = MD; + } +} + +static BaseOffset ComputeBaseOffset(ASTContext &Context, + const CXXRecordDecl *DerivedRD, + const CXXBasePath &Path) { + int64_t NonVirtualOffset = 0; + + unsigned NonVirtualStart = 0; + const CXXRecordDecl *VirtualBase = 0; + + // First, look for the virtual base class. + for (unsigned I = 0, E = Path.size(); I != E; ++I) { + const CXXBasePathElement &Element = Path[I]; + + if (Element.Base->isVirtual()) { + // FIXME: Can we break when we find the first virtual base? + // (If we can't, can't we just iterate over the path in reverse order?) + NonVirtualStart = I + 1; + QualType VBaseType = Element.Base->getType(); + VirtualBase = + cast<CXXRecordDecl>(VBaseType->getAs<RecordType>()->getDecl()); + } + } + + // 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 RecordType *BaseType = Element.Base->getType()->getAs<RecordType>(); + const CXXRecordDecl *Base = cast<CXXRecordDecl>(BaseType->getDecl()); + + 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 / 8); + +} + +static BaseOffset ComputeBaseOffset(ASTContext &Context, + const CXXRecordDecl *BaseRD, + const CXXRecordDecl *DerivedRD) { + CXXBasePaths Paths(/*FindAmbiguities=*/false, + /*RecordPaths=*/true, /*DetectVirtual=*/false); + + if (!const_cast<CXXRecordDecl *>(DerivedRD)-> + isDerivedFrom(const_cast<CXXRecordDecl *>(BaseRD), Paths)) { + assert(false && "Class must be derived from the passed in base class!"); + return BaseOffset(); + } + + 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->getResultType()); + CanQualType CanBaseReturnType = + Context.getCanonicalType(BaseFT->getResultType()); + + 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 { + assert(false && "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::PropagateOverrider(const CXXMethodDecl *OldMD, + BaseSubobject NewBase, + uint64_t OverriderOffsetInLayoutClass, + const CXXMethodDecl *NewMD, + SubobjectOffsetsMapTy &Offsets) { + for (CXXMethodDecl::method_iterator I = OldMD->begin_overridden_methods(), + E = OldMD->end_overridden_methods(); I != E; ++I) { + const CXXMethodDecl *OverriddenMD = *I; + const CXXRecordDecl *OverriddenRD = OverriddenMD->getParent(); + + // We want to override OverriddenMD in all subobjects, for example: + // + /// struct A { virtual void f(); }; + /// struct B1 : A { }; + /// struct B2 : A { }; + /// struct C : B1, B2 { virtual void f(); }; + /// + /// When overriding A::f with C::f we need to do so in both A subobjects. + const OffsetSetVectorTy &OffsetVector = Offsets[OverriddenRD]; + + // Go through all the subobjects. + for (unsigned I = 0, E = OffsetVector.size(); I != E; ++I) { + uint64_t Offset = OffsetVector[I]; + + BaseSubobject OverriddenSubobject = BaseSubobject(OverriddenRD, Offset); + BaseSubobjectMethodPairTy SubobjectAndMethod = + std::make_pair(OverriddenSubobject, OverriddenMD); + + OverriderInfo &Overrider = OverridersMap[SubobjectAndMethod]; + + assert(Overrider.Method && "Did not find existing overrider!"); + + // Check if we need return adjustments or base adjustments. + // (We don't want to do this for pure virtual member functions). + if (!NewMD->isPure()) { + // Get the return adjustment base offset. + BaseOffset ReturnBaseOffset = + ComputeReturnAdjustmentBaseOffset(Context, NewMD, OverriddenMD); + + if (!ReturnBaseOffset.isEmpty()) { + // Store the return adjustment base offset. + ReturnAdjustments[SubobjectAndMethod] = ReturnBaseOffset; + } + } + + // Set the new overrider. + Overrider.Offset = OverriderOffsetInLayoutClass; + Overrider.Method = NewMD; + + // And propagate it further. + PropagateOverrider(OverriddenMD, NewBase, OverriderOffsetInLayoutClass, + NewMD, Offsets); + } + } +} + +void +FinalOverriders::MergeSubobjectOffsets(const SubobjectOffsetsMapTy &NewOffsets, + SubobjectOffsetsMapTy &Offsets) { + // Iterate over the new offsets. + for (SubobjectOffsetsMapTy::const_iterator I = NewOffsets.begin(), + E = NewOffsets.end(); I != E; ++I) { + const CXXRecordDecl *NewRD = I->first; + const OffsetSetVectorTy& NewOffsetVector = I->second; + + OffsetSetVectorTy &OffsetVector = Offsets[NewRD]; + + // Merge the new offsets set vector into the old. + OffsetVector.insert(NewOffsetVector.begin(), NewOffsetVector.end()); + } +} + +void FinalOverriders::ComputeFinalOverriders(BaseSubobject Base, + bool BaseSubobjectIsVisitedVBase, + uint64_t OffsetInLayoutClass, + SubobjectOffsetsMapTy &Offsets) { + const CXXRecordDecl *RD = Base.getBase(); + const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); + + SubobjectOffsetsMapTy NewOffsets; + + for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), + E = RD->bases_end(); I != E; ++I) { + const CXXRecordDecl *BaseDecl = + cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); + + // Ignore bases that don't have any virtual member functions. + if (!BaseDecl->isPolymorphic()) + continue; + + bool IsVisitedVirtualBase = BaseSubobjectIsVisitedVBase; + uint64_t BaseOffset; + uint64_t BaseOffsetInLayoutClass; + if (I->isVirtual()) { + if (!VisitedVirtualBases.insert(BaseDecl)) + IsVisitedVirtualBase = true; + BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl); + + const ASTRecordLayout &LayoutClassLayout = + Context.getASTRecordLayout(LayoutClass); + BaseOffsetInLayoutClass = + LayoutClassLayout.getVBaseClassOffset(BaseDecl); + } else { + BaseOffset = Layout.getBaseClassOffset(BaseDecl) + Base.getBaseOffset(); + BaseOffsetInLayoutClass = Layout.getBaseClassOffset(BaseDecl) + + OffsetInLayoutClass; + } + + // Compute the final overriders for this base. + // We always want to compute the final overriders, even if the base is a + // visited virtual base. Consider: + // + // struct A { + // virtual void f(); + // virtual void g(); + // }; + // + // struct B : virtual A { + // void f(); + // }; + // + // struct C : virtual A { + // void g (); + // }; + // + // struct D : B, C { }; + // + // Here, we still want to compute the overriders for A as a base of C, + // because otherwise we'll miss that C::g overrides A::f. + ComputeFinalOverriders(BaseSubobject(BaseDecl, BaseOffset), + IsVisitedVirtualBase, BaseOffsetInLayoutClass, + NewOffsets); + } + + /// Now add the overriders for this particular subobject. + /// (We don't want to do this more than once for a virtual base). + if (!BaseSubobjectIsVisitedVBase) + AddOverriders(Base, OffsetInLayoutClass, NewOffsets); + + // And merge the newly discovered subobject offsets. + MergeSubobjectOffsets(NewOffsets, Offsets); + + /// Finally, add the offset for our own subobject. + Offsets[RD].insert(Base.getBaseOffset()); +} + +void FinalOverriders::dump(llvm::raw_ostream &Out, BaseSubobject Base) { + const CXXRecordDecl *RD = Base.getBase(); + const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); + + for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), + E = RD->bases_end(); I != E; ++I) { + const CXXRecordDecl *BaseDecl = + cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); + + // Ignore bases that don't have any virtual member functions. + if (!BaseDecl->isPolymorphic()) + continue; + + uint64_t BaseOffset; + if (I->isVirtual()) { + if (!VisitedVirtualBases.insert(BaseDecl)) { + // We've visited this base before. + continue; + } + + BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl); + } else { + BaseOffset = Layout.getBaseClassOffset(BaseDecl) + + Base.getBaseOffset(); + } + + dump(Out, BaseSubobject(BaseDecl, BaseOffset)); + } + + Out << "Final overriders for (" << RD->getQualifiedNameAsString() << ", "; + Out << Base.getBaseOffset() / 8 << ")\n"; + + // Now dump the overriders for this base subobject. + for (CXXRecordDecl::method_iterator I = RD->method_begin(), + E = RD->method_end(); I != E; ++I) { + const CXXMethodDecl *MD = *I; + + if (!MD->isVirtual()) + continue; + + OverriderInfo Overrider = getOverrider(Base, MD); + + Out << " " << MD->getQualifiedNameAsString() << " - ("; + Out << Overrider.Method->getQualifiedNameAsString(); + Out << ", " << ", " << Overrider.Offset / 8 << ')'; + + AdjustmentOffsetsMapTy::const_iterator AI = + ReturnAdjustments.find(std::make_pair(Base, MD)); + if (AI != ReturnAdjustments.end()) { + const BaseOffset &Offset = AI->second; + + Out << " [ret-adj: "; + if (Offset.VirtualBase) + Out << Offset.VirtualBase->getQualifiedNameAsString() << " vbase, "; + + Out << Offset.NonVirtualOffset << " nv]"; + } + + Out << "\n"; + } +} + +/// VTableComponent - Represents a single component in a vtable. +class VTableComponent { +public: + enum Kind { + CK_VCallOffset, + CK_VBaseOffset, + CK_OffsetToTop, + CK_RTTI, + CK_FunctionPointer, + + /// CK_CompleteDtorPointer - A pointer to the complete destructor. + CK_CompleteDtorPointer, + + /// CK_DeletingDtorPointer - A pointer to the deleting destructor. + CK_DeletingDtorPointer, + + /// CK_UnusedFunctionPointer - In some cases, a vtable function pointer + /// will end up never being called. Such vtable function pointers are + /// represented as a CK_UnusedFunctionPointer. + CK_UnusedFunctionPointer + }; + + static VTableComponent MakeVCallOffset(int64_t Offset) { + return VTableComponent(CK_VCallOffset, Offset); + } + + static VTableComponent MakeVBaseOffset(int64_t Offset) { + return VTableComponent(CK_VBaseOffset, Offset); + } + + static VTableComponent MakeOffsetToTop(int64_t Offset) { + return VTableComponent(CK_OffsetToTop, Offset); + } + + static VTableComponent MakeRTTI(const CXXRecordDecl *RD) { + return VTableComponent(CK_RTTI, reinterpret_cast<uintptr_t>(RD)); + } + + static VTableComponent MakeFunction(const CXXMethodDecl *MD) { + assert(!isa<CXXDestructorDecl>(MD) && + "Don't use MakeFunction with destructors!"); + + return VTableComponent(CK_FunctionPointer, + reinterpret_cast<uintptr_t>(MD)); + } + + static VTableComponent MakeCompleteDtor(const CXXDestructorDecl *DD) { + return VTableComponent(CK_CompleteDtorPointer, + reinterpret_cast<uintptr_t>(DD)); + } + + static VTableComponent MakeDeletingDtor(const CXXDestructorDecl *DD) { + return VTableComponent(CK_DeletingDtorPointer, + reinterpret_cast<uintptr_t>(DD)); + } + + static VTableComponent MakeUnusedFunction(const CXXMethodDecl *MD) { + assert(!isa<CXXDestructorDecl>(MD) && + "Don't use MakeUnusedFunction with destructors!"); + return VTableComponent(CK_UnusedFunctionPointer, + reinterpret_cast<uintptr_t>(MD)); + } + + static VTableComponent getFromOpaqueInteger(uint64_t I) { + return VTableComponent(I); + } + + /// getKind - Get the kind of this vtable component. + Kind getKind() const { + return (Kind)(Value & 0x7); + } + + int64_t getVCallOffset() const { + assert(getKind() == CK_VCallOffset && "Invalid component kind!"); + + return getOffset(); + } + + int64_t getVBaseOffset() const { + assert(getKind() == CK_VBaseOffset && "Invalid component kind!"); + + return getOffset(); + } + + int64_t getOffsetToTop() const { + assert(getKind() == CK_OffsetToTop && "Invalid component kind!"); + + return getOffset(); + } + + const CXXRecordDecl *getRTTIDecl() const { + assert(getKind() == CK_RTTI && "Invalid component kind!"); + + return reinterpret_cast<CXXRecordDecl *>(getPointer()); + } + + const CXXMethodDecl *getFunctionDecl() const { + assert(getKind() == CK_FunctionPointer); + + return reinterpret_cast<CXXMethodDecl *>(getPointer()); + } + + const CXXDestructorDecl *getDestructorDecl() const { + assert((getKind() == CK_CompleteDtorPointer || + getKind() == CK_DeletingDtorPointer) && "Invalid component kind!"); + + return reinterpret_cast<CXXDestructorDecl *>(getPointer()); + } + + const CXXMethodDecl *getUnusedFunctionDecl() const { + assert(getKind() == CK_UnusedFunctionPointer); + + return reinterpret_cast<CXXMethodDecl *>(getPointer()); + } + +private: + VTableComponent(Kind ComponentKind, int64_t Offset) { + assert((ComponentKind == CK_VCallOffset || + ComponentKind == CK_VBaseOffset || + ComponentKind == CK_OffsetToTop) && "Invalid component kind!"); + assert(Offset <= ((1LL << 56) - 1) && "Offset is too big!"); + + Value = ((Offset << 3) | ComponentKind); + } + + VTableComponent(Kind ComponentKind, uintptr_t Ptr) { + assert((ComponentKind == CK_RTTI || + ComponentKind == CK_FunctionPointer || + ComponentKind == CK_CompleteDtorPointer || + ComponentKind == CK_DeletingDtorPointer || + ComponentKind == CK_UnusedFunctionPointer) && + "Invalid component kind!"); + + assert((Ptr & 7) == 0 && "Pointer not sufficiently aligned!"); + + Value = Ptr | ComponentKind; + } + + int64_t getOffset() const { + assert((getKind() == CK_VCallOffset || getKind() == CK_VBaseOffset || + getKind() == CK_OffsetToTop) && "Invalid component kind!"); + + return Value >> 3; + } + + uintptr_t getPointer() const { + assert((getKind() == CK_RTTI || + getKind() == CK_FunctionPointer || + getKind() == CK_CompleteDtorPointer || + getKind() == CK_DeletingDtorPointer || + getKind() == CK_UnusedFunctionPointer) && + "Invalid component kind!"); + + return static_cast<uintptr_t>(Value & ~7ULL); + } + + explicit VTableComponent(uint64_t Value) + : Value(Value) { } + + /// The kind is stored in the lower 3 bits of the value. For offsets, we + /// make use of the facts that classes can't be larger than 2^55 bytes, + /// so we store the offset in the lower part of the 61 bytes that remain. + /// (The reason that we're not simply using a PointerIntPair here is that we + /// need the offsets to be 64-bit, even when on a 32-bit machine). + int64_t Value; +}; + +/// VCallOffsetMap - Keeps track of vcall offsets when building a vtable. +struct VCallOffsetMap { + + typedef std::pair<const CXXMethodDecl *, int64_t> MethodAndOffsetPairTy; + + /// Offsets - Keeps track of methods and their offsets. + // FIXME: This should be a real map and not a vector. + llvm::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, int64_t OffsetOffset); + + /// getVCallOffsetOffset - Returns the vcall offset offset (relative to the + /// vtable address point) for the given virtual member function. + int64_t 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) { + ASTContext &C = LHS->getASTContext(); // TODO: thread this down + CanQual<FunctionProtoType> + LT = C.getCanonicalType(LHS->getType()).getAs<FunctionProtoType>(), + RT = C.getCanonicalType(RHS->getType()).getAs<FunctionProtoType>(); + + // 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.getQualifiers() != RT.getQualifiers() || + LT->getNumArgs() != RT->getNumArgs()) + return false; + for (unsigned I = 0, E = LT->getNumArgs(); I != E; ++I) + if (LT->getArgType(I) != RT->getArgType(I)) + return false; + return true; +} + +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, + int64_t OffsetOffset) { + // Check if we can reuse an offset. + for (unsigned I = 0, E = Offsets.size(); I != E; ++I) { + if (MethodsCanShareVCallOffset(Offsets[I].first, MD)) + return false; + } + + // Add the offset. + Offsets.push_back(MethodAndOffsetPairTy(MD, OffsetOffset)); + return true; +} + +int64_t VCallOffsetMap::getVCallOffsetOffset(const CXXMethodDecl *MD) { + // Look for an offset. + for (unsigned I = 0, E = Offsets.size(); I != E; ++I) { + if (MethodsCanShareVCallOffset(Offsets[I].first, MD)) + return Offsets[I].second; + } + + assert(false && "Should always find a vcall offset offset!"); + return 0; +} + +/// VCallAndVBaseOffsetBuilder - Class for building vcall and vbase offsets. +class VCallAndVBaseOffsetBuilder { +public: + typedef llvm::DenseMap<const CXXRecordDecl *, int64_t> + 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 llvm::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, + uint64_t RealBaseOffset); + + /// AddVCallOffsets - Add vcall offsets for the given base subobject. + void AddVCallOffsets(BaseSubobject Base, uint64_t VBaseOffset); + + /// AddVBaseOffsets - Add vbase offsets for the given class. + void AddVBaseOffsets(const CXXRecordDecl *Base, uint64_t OffsetInLayoutClass); + + /// getCurrentOffsetOffset - Get the current vcall or vbase offset offset in + /// bytes, relative to the vtable address point. + int64_t getCurrentOffsetOffset() const; + +public: + VCallAndVBaseOffsetBuilder(const CXXRecordDecl *MostDerivedClass, + const CXXRecordDecl *LayoutClass, + const FinalOverriders *Overriders, + BaseSubobject Base, bool BaseIsVirtual, + uint64_t 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, + uint64_t 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.getPrimaryBaseWasVirtual(); + + uint64_t PrimaryBaseOffset; + + // Get the base offset of the primary base. + if (PrimaryBaseIsVirtual) { + assert(Layout.getVBaseClassOffset(PrimaryBase) == 0 && + "Primary vbase should have a zero offset!"); + + const ASTRecordLayout &MostDerivedClassLayout = + Context.getASTRecordLayout(MostDerivedClass); + + PrimaryBaseOffset = + MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase); + } else { + assert(Layout.getBaseClassOffset(PrimaryBase) == 0 && + "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); +} + +int64_t 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()); + + // FIXME: We shouldn't use / 8 here. + int64_t OffsetOffset = OffsetIndex * + (int64_t)Context.Target.getPointerWidth(0) / 8; + + return OffsetOffset; +} + +void VCallAndVBaseOffsetBuilder::AddVCallOffsets(BaseSubobject Base, + uint64_t 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.getPrimaryBaseWasVirtual()) { + // Get the base offset of the primary base. + assert(Layout.getBaseClassOffset(PrimaryBase) == 0 && + "Primary base should have a zero offset!"); + + AddVCallOffsets(BaseSubobject(PrimaryBase, Base.getBaseOffset()), + VBaseOffset); + } + + // Add the vcall offsets. + for (CXXRecordDecl::method_iterator I = RD->method_begin(), + E = RD->method_end(); I != E; ++I) { + const CXXMethodDecl *MD = *I; + + if (!MD->isVirtual()) + continue; + + int64_t OffsetOffset = getCurrentOffsetOffset(); + + // Don't add a vcall offset if we already have one for this member function + // signature. + if (!VCallOffsets.AddVCallOffset(MD, OffsetOffset)) + continue; + + int64_t Offset = 0; + + if (Overriders) { + // Get the final overrider. + FinalOverriders::OverriderInfo Overrider = + Overriders->getOverrider(Base, MD); + + /// The vcall offset is the offset from the virtual base to the object + /// where the function was overridden. + // FIXME: We should not use / 8 here. + Offset = (int64_t)(Overrider.Offset - VBaseOffset) / 8; + } + + Components.push_back(VTableComponent::MakeVCallOffset(Offset)); + } + + // And iterate over all non-virtual bases (ignoring the primary base). + for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), + E = RD->bases_end(); I != E; ++I) { + + if (I->isVirtual()) + continue; + + const CXXRecordDecl *BaseDecl = + cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); + if (BaseDecl == PrimaryBase) + continue; + + // Get the base offset of this base. + uint64_t BaseOffset = Base.getBaseOffset() + + Layout.getBaseClassOffset(BaseDecl); + + AddVCallOffsets(BaseSubobject(BaseDecl, BaseOffset), VBaseOffset); + } +} + +void VCallAndVBaseOffsetBuilder::AddVBaseOffsets(const CXXRecordDecl *RD, + uint64_t OffsetInLayoutClass) { + const ASTRecordLayout &LayoutClassLayout = + Context.getASTRecordLayout(LayoutClass); + + // Add vbase offsets. + for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), + E = RD->bases_end(); I != E; ++I) { + const CXXRecordDecl *BaseDecl = + cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); + + // Check if this is a virtual base that we haven't visited before. + if (I->isVirtual() && VisitedVirtualBases.insert(BaseDecl)) { + // FIXME: We shouldn't use / 8 here. + int64_t Offset = + (int64_t)(LayoutClassLayout.getVBaseClassOffset(BaseDecl) - + OffsetInLayoutClass) / 8; + + // Add the vbase offset offset. + assert(!VBaseOffsetOffsets.count(BaseDecl) && + "vbase offset offset already exists!"); + + int64_t 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); + } +} + +/// VTableBuilder - Class for building vtable layout information. +class VTableBuilder { +public: + /// PrimaryBasesSetVectorTy - A set vector of direct and indirect + /// primary bases. + typedef llvm::SmallSetVector<const CXXRecordDecl *, 8> + PrimaryBasesSetVectorTy; + + typedef llvm::DenseMap<const CXXRecordDecl *, int64_t> + VBaseOffsetOffsetsMapTy; + + typedef llvm::DenseMap<BaseSubobject, uint64_t> + AddressPointsMapTy; + +private: + /// VTables - Global vtable information. + CodeGenVTables &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 uint64_t 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. + llvm::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 uint64_t BaseOffset; + + /// BaseOffsetInLayoutClass - The base offset in the layout class of this + /// method. + const uint64_t 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(uint64_t BaseOffset, uint64_t BaseOffsetInLayoutClass, + uint64_t VTableIndex) + : BaseOffset(BaseOffset), + BaseOffsetInLayoutClass(BaseOffsetInLayoutClass), + VTableIndex(VTableIndex) { } + + MethodInfo() : BaseOffset(0), BaseOffsetInLayoutClass(0), VTableIndex(0) { } + }; + + typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy; + + /// MethodInfoMap - The information for all methods in the vtable we're + /// currently building. + MethodInfoMapTy MethodInfoMap; + + typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy; + + /// VTableThunks - The thunks by vtable index in the vtable currently being + /// built. + VTableThunksMapTy VTableThunks; + + typedef llvm::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, + uint64_t 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, + uint64_t BaseOffsetInLayoutClass, + const CXXRecordDecl *FirstBaseInPrimaryBaseChain, + uint64_t FirstBaseOffsetInLayoutClass) const; + + + /// AddMethods - Add the methods of this base subobject and all its + /// primary bases to the vtable components vector. + void AddMethods(BaseSubobject Base, uint64_t BaseOffsetInLayoutClass, + const CXXRecordDecl *FirstBaseInPrimaryBaseChain, + uint64_t 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, + uint64_t 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, + uint64_t OffsetInLayoutClass); + + /// DeterminePrimaryVirtualBases - Determine the primary virtual bases in this + /// class hierarchy. + void DeterminePrimaryVirtualBases(const CXXRecordDecl *RD, + uint64_t 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: + VTableBuilder(CodeGenVTables &VTables, const CXXRecordDecl *MostDerivedClass, + uint64_t MostDerivedClassOffset, bool MostDerivedClassIsVirtual, + const CXXRecordDecl *LayoutClass) + : VTables(VTables), MostDerivedClass(MostDerivedClass), + MostDerivedClassOffset(MostDerivedClassOffset), + MostDerivedClassIsVirtual(MostDerivedClassIsVirtual), + LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()), + Overriders(MostDerivedClass, MostDerivedClassOffset, LayoutClass) { + + LayoutVTable(); + } + + ThunksMapTy::const_iterator thunks_begin() const { + return Thunks.begin(); + } + + ThunksMapTy::const_iterator thunks_end() const { + return Thunks.end(); + } + + const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const { + return VBaseOffsetOffsets; + } + + /// getNumVTableComponents - Return the number of components in the vtable + /// currently built. + uint64_t getNumVTableComponents() const { + return Components.size(); + } + + const uint64_t *vtable_components_data_begin() const { + return reinterpret_cast<const uint64_t *>(Components.begin()); + } + + const uint64_t *vtable_components_data_end() const { + return reinterpret_cast<const uint64_t *>(Components.end()); + } + + 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(llvm::raw_ostream&); +}; + +void VTableBuilder::AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk) { + assert(!isBuildingConstructorVTable() && + "Can't add thunks for construction vtable"); + + llvm::SmallVector<ThunkInfo, 1> &ThunksVector = Thunks[MD]; + + // Check if we have this thunk already. + if (std::find(ThunksVector.begin(), ThunksVector.end(), Thunk) != + ThunksVector.end()) + return; + + ThunksVector.push_back(Thunk); +} + +typedef llvm::SmallPtrSet<const CXXMethodDecl *, 8> OverriddenMethodsSetTy; + +/// 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) { + assert(MD->isVirtual() && "Method is not virtual!"); + + for (CXXMethodDecl::method_iterator I = MD->begin_overridden_methods(), + E = MD->end_overridden_methods(); I != E; ++I) { + const CXXMethodDecl *OverriddenMD = *I; + + OverriddenMethods.insert(OverriddenMD); + + ComputeAllOverriddenMethods(OverriddenMD, OverriddenMethods); + } +} + +void VTableBuilder::ComputeThisAdjustments() { + // Now go through the method info map and see if any of the methods need + // 'this' pointer adjustments. + for (MethodInfoMapTy::const_iterator I = MethodInfoMap.begin(), + E = MethodInfoMap.end(); I != E; ++I) { + const CXXMethodDecl *MD = I->first; + const MethodInfo &MethodInfo = I->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(BaseSubobject(MD->getParent(), + MethodInfo.BaseOffset), MD); + + // 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 (VTableThunksMapTy::const_iterator I = VTableThunks.begin(), + E = VTableThunks.end(); I != E; ++I) { + const VTableComponent &Component = Components[I->first]; + const ThunkInfo &Thunk = I->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 VTableBuilder::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.VBaseOffsetOffset = + VBaseOffsetOffsets.lookup(Offset.VirtualBase); + } else { + Adjustment.VBaseOffsetOffset = + VTables.getVirtualBaseOffsetOffset(Offset.DerivedClass, + Offset.VirtualBase); + } + } + + Adjustment.NonVirtual = Offset.NonVirtualOffset; + } + + return Adjustment; +} + +BaseOffset +VTableBuilder::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 (!const_cast<CXXRecordDecl *>(DerivedRD)-> + isDerivedFrom(const_cast<CXXRecordDecl *>(BaseRD), Paths)) { + assert(false && "Class must be derived from the passed in base class!"); + return BaseOffset(); + } + + // We have to go through all the paths, and see which one leads us to the + // right base subobject. + for (CXXBasePaths::const_paths_iterator I = Paths.begin(), E = Paths.end(); + I != E; ++I) { + BaseOffset Offset = ComputeBaseOffset(Context, DerivedRD, *I); + + // FIXME: Should not use * 8 here. + uint64_t OffsetToBaseSubobject = Offset.NonVirtualOffset * 8; + + 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 +VTableBuilder::ComputeThisAdjustment(const CXXMethodDecl *MD, + uint64_t 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, + /*FinalOverriders=*/0, + BaseSubobject(Offset.VirtualBase, 0), + /*BaseIsVirtual=*/true, + /*OffsetInLayoutClass=*/0); + + VCallOffsets = Builder.getVCallOffsets(); + } + + Adjustment.VCallOffsetOffset = VCallOffsets.getVCallOffsetOffset(MD); + } + + // Set the non-virtual part of the adjustment. + Adjustment.NonVirtual = Offset.NonVirtualOffset; + + return Adjustment; +} + +void +VTableBuilder::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, + VTableBuilder::PrimaryBasesSetVectorTy &Bases) { + if (Bases.count(MD->getParent())) + return true; + + for (CXXMethodDecl::method_iterator I = MD->begin_overridden_methods(), + E = MD->end_overridden_methods(); I != E; ++I) { + const CXXMethodDecl *OverriddenMD = *I; + + // Check "indirect overriders". + if (OverridesIndirectMethodInBases(OverriddenMD, Bases)) + return true; + } + + return false; +} + +bool +VTableBuilder::IsOverriderUsed(const CXXMethodDecl *Overrider, + uint64_t BaseOffsetInLayoutClass, + const CXXRecordDecl *FirstBaseInPrimaryBaseChain, + uint64_t 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; + + VTableBuilder::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.getPrimaryBaseWasVirtual()) { + assert(Layout.getVBaseClassOffset(PrimaryBase) == 0 && + "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) == 0 && + "Primary base should always be at offset 0!"); + } + + if (!PrimaryBases.insert(PrimaryBase)) + assert(false && "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); +} + +/// FindNearestOverriddenMethod - Given a method, returns the overridden method +/// from the nearest base. Returns null if no method was found. +static const CXXMethodDecl * +FindNearestOverriddenMethod(const CXXMethodDecl *MD, + VTableBuilder::PrimaryBasesSetVectorTy &Bases) { + OverriddenMethodsSetTy OverriddenMethods; + ComputeAllOverriddenMethods(MD, OverriddenMethods); + + for (int I = Bases.size(), E = 0; I != E; --I) { + const CXXRecordDecl *PrimaryBase = Bases[I - 1]; + + // Now check the overriden methods. + for (OverriddenMethodsSetTy::const_iterator I = OverriddenMethods.begin(), + E = OverriddenMethods.end(); I != E; ++I) { + const CXXMethodDecl *OverriddenMD = *I; + + // We found our overridden method. + if (OverriddenMD->getParent() == PrimaryBase) + return OverriddenMD; + } + } + + return 0; +} + +void +VTableBuilder::AddMethods(BaseSubobject Base, uint64_t BaseOffsetInLayoutClass, + const CXXRecordDecl *FirstBaseInPrimaryBaseChain, + uint64_t FirstBaseOffsetInLayoutClass, + PrimaryBasesSetVectorTy &PrimaryBases) { + const CXXRecordDecl *RD = Base.getBase(); + const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); + + if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) { + uint64_t PrimaryBaseOffset; + uint64_t PrimaryBaseOffsetInLayoutClass; + if (Layout.getPrimaryBaseWasVirtual()) { + assert(Layout.getVBaseClassOffset(PrimaryBase) == 0 && + "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) == 0 && + "Primary base should have a zero offset!"); + + PrimaryBaseOffset = Base.getBaseOffset(); + PrimaryBaseOffsetInLayoutClass = BaseOffsetInLayoutClass; + } + + AddMethods(BaseSubobject(PrimaryBase, PrimaryBaseOffset), + PrimaryBaseOffsetInLayoutClass, FirstBaseInPrimaryBaseChain, + FirstBaseOffsetInLayoutClass, PrimaryBases); + + if (!PrimaryBases.insert(PrimaryBase)) + assert(false && "Found a duplicate primary base!"); + } + + // Now go through all virtual member functions and add them. + for (CXXRecordDecl::method_iterator I = RD->method_begin(), + E = RD->method_end(); I != E; ++I) { + const CXXMethodDecl *MD = *I; + + if (!MD->isVirtual()) + continue; + + // Get the final overrider. + FinalOverriders::OverriderInfo Overrider = + Overriders.getOverrider(Base, MD); + + // 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.VCallOffsetOffset && + Overrider.Method->getParent() == MostDerivedClass) { + // This is a virtual thunk for the most derived class, add it. + AddThunk(Overrider.Method, + ThunkInfo(ThisAdjustment, ReturnAdjustment())); + } + } + + continue; + } + } + + // 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. + BaseOffset ReturnAdjustmentOffset = + Overriders.getReturnAdjustmentOffset(Base, MD); + + ReturnAdjustment ReturnAdjustment = + ComputeReturnAdjustment(ReturnAdjustmentOffset); + + AddMethod(Overrider.Method, ReturnAdjustment); + } +} + +void VTableBuilder::LayoutVTable() { + LayoutPrimaryAndSecondaryVTables(BaseSubobject(MostDerivedClass, 0), + /*BaseIsMorallyVirtual=*/false, + MostDerivedClassIsVirtual, + MostDerivedClassOffset); + + VisitedVirtualBasesSetTy VBases; + + // Determine the primary virtual bases. + DeterminePrimaryVirtualBases(MostDerivedClass, MostDerivedClassOffset, + VBases); + VBases.clear(); + + LayoutVTablesForVirtualBases(MostDerivedClass, VBases); +} + +void +VTableBuilder::LayoutPrimaryAndSecondaryVTables(BaseSubobject Base, + bool BaseIsMorallyVirtual, + bool BaseIsVirtualInLayoutClass, + uint64_t OffsetInLayoutClass) { + assert(Base.getBase()->isDynamicClass() && "class does not have a vtable!"); + + // 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. + // FIXME: We should not use / 8 here. + int64_t OffsetToTop = -(int64_t)(OffsetInLayoutClass - + MostDerivedClassOffset) / 8; + 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); + + // Compute 'this' pointer adjustments. + ComputeThisAdjustments(); + + // Add all address points. + const CXXRecordDecl *RD = Base.getBase(); + while (true) { + AddressPoints.insert(std::make_pair(BaseSubobject(RD, OffsetInLayoutClass), + AddressPoint)); + + const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); + const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); + + if (!PrimaryBase) + break; + + if (Layout.getPrimaryBaseWasVirtual()) { + // 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 VTableBuilder::LayoutSecondaryVTables(BaseSubobject Base, + bool BaseIsMorallyVirtual, + uint64_t 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 (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), + E = RD->bases_end(); I != E; ++I) { + // Ignore virtual bases, we'll emit them later. + if (I->isVirtual()) + continue; + + const CXXRecordDecl *BaseDecl = + cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); + + // 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. + uint64_t RelativeBaseOffset = Layout.getBaseClassOffset(BaseDecl); + uint64_t BaseOffset = Base.getBaseOffset() + RelativeBaseOffset; + + uint64_t 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 +VTableBuilder::DeterminePrimaryVirtualBases(const CXXRecordDecl *RD, + uint64_t 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.getPrimaryBaseWasVirtual()) { + 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); + + uint64_t 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 (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), + E = RD->bases_end(); I != E; ++I) { + const CXXRecordDecl *BaseDecl = + cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); + + uint64_t BaseOffsetInLayoutClass; + + if (I->isVirtual()) { + if (!VBases.insert(BaseDecl)) + continue; + + const ASTRecordLayout &LayoutClassLayout = + Context.getASTRecordLayout(LayoutClass); + + BaseOffsetInLayoutClass = LayoutClassLayout.getVBaseClassOffset(BaseDecl); + } else { + BaseOffsetInLayoutClass = + OffsetInLayoutClass + Layout.getBaseClassOffset(BaseDecl); + } + + DeterminePrimaryVirtualBases(BaseDecl, BaseOffsetInLayoutClass, VBases); + } +} + +void +VTableBuilder::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 (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), + E = RD->bases_end(); I != E; ++I) { + const CXXRecordDecl *BaseDecl = + cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); + + // 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 (I->isVirtual() && BaseDecl->isDynamicClass() && + !PrimaryVirtualBases.count(BaseDecl) && VBases.insert(BaseDecl)) { + const ASTRecordLayout &MostDerivedClassLayout = + Context.getASTRecordLayout(MostDerivedClass); + uint64_t BaseOffset = + MostDerivedClassLayout.getVBaseClassOffset(BaseDecl); + + const ASTRecordLayout &LayoutClassLayout = + Context.getASTRecordLayout(LayoutClass); + uint64_t 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 VTableBuilder::dumpLayout(llvm::raw_ostream& Out) { + + if (isBuildingConstructorVTable()) { + Out << "Construction vtable for ('"; + Out << MostDerivedClass->getQualifiedNameAsString() << "', "; + // FIXME: Don't use / 8 . + Out << MostDerivedClassOffset / 8 << ") in '"; + Out << LayoutClass->getQualifiedNameAsString(); + } else { + Out << "Vtable for '"; + Out << MostDerivedClass->getQualifiedNameAsString(); + } + 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 (AddressPointsMapTy::const_iterator I = AddressPoints.begin(), + E = AddressPoints.end(); I != E; ++I) { + const BaseSubobject& Base = I->first; + uint64_t Index = I->second; + + 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() << ")"; + break; + + case VTableComponent::CK_VBaseOffset: + Out << "vbase_offset (" << Component.getVBaseOffset() << ")"; + break; + + case VTableComponent::CK_OffsetToTop: + Out << "offset_to_top (" << Component.getOffsetToTop() << ")"; + break; + + case VTableComponent::CK_RTTI: + Out << Component.getRTTIDecl()->getQualifiedNameAsString() << " 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]"; + + 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.VBaseOffsetOffset) { + Out << ", " << Thunk.Return.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.VCallOffsetOffset) { + Out << ", " << Thunk.This.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(); + + Out << DD->getQualifiedNameAsString(); + 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.VCallOffsetOffset) { + Out << ", " << Thunk.This.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; + + // FIXME: Instead of dividing by 8, we should be using CharUnits. + Out << " -- (" << Base.getBase()->getQualifiedNameAsString(); + Out << ", " << Base.getBaseOffset() / 8 << ") vtable address --\n"; + } else { + uint64_t 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 (std::multimap<uint64_t, BaseSubobject>::const_iterator I = + AddressPointsByIndex.lower_bound(NextIndex), E = + AddressPointsByIndex.upper_bound(NextIndex); I != E; ++I) { + assert(I->second.getBaseOffset() == BaseOffset && + "Invalid base offset!"); + const CXXRecordDecl *RD = I->second.getBase(); + ClassNames.insert(RD->getQualifiedNameAsString()); + } + + for (std::set<std::string>::const_iterator I = ClassNames.begin(), + E = ClassNames.end(); I != E; ++I) { + // FIXME: Instead of dividing by 8, we should be using CharUnits. + Out << " -- (" << *I; + Out << ", " << BaseOffset / 8 << ") 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, int64_t> ClassNamesAndOffsets; + for (VBaseOffsetOffsetsMapTy::const_iterator I = VBaseOffsetOffsets.begin(), + E = VBaseOffsetOffsets.end(); I != E; ++I) { + std::string ClassName = I->first->getQualifiedNameAsString(); + int64_t OffsetOffset = I->second; + ClassNamesAndOffsets.insert(std::make_pair(ClassName, OffsetOffset)); + } + + Out << "Virtual base offset offsets for '"; + Out << MostDerivedClass->getQualifiedNameAsString() << "' ("; + Out << ClassNamesAndOffsets.size(); + Out << (ClassNamesAndOffsets.size() == 1 ? " entry" : " entries") << ").\n"; + + for (std::map<std::string, int64_t>::const_iterator I = + ClassNamesAndOffsets.begin(), E = ClassNamesAndOffsets.end(); + I != E; ++I) + Out << " " << I->first << " | " << I->second << '\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 (ThunksMapTy::const_iterator I = Thunks.begin(), E = Thunks.end(); + I != E; ++I) { + const CXXMethodDecl *MD = I->first; + std::string MethodName = + PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual, + MD); + + MethodNamesAndDecls.insert(std::make_pair(MethodName, MD)); + } + + for (std::map<std::string, const CXXMethodDecl *>::const_iterator I = + MethodNamesAndDecls.begin(), E = MethodNamesAndDecls.end(); + I != E; ++I) { + const std::string &MethodName = I->first; + const CXXMethodDecl *MD = I->second; + + ThunkInfoVectorTy ThunksVector = Thunks[MD]; + std::sort(ThunksVector.begin(), ThunksVector.end()); + + 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.This.NonVirtual; + Out << " non-virtual"; + if (Thunk.Return.VBaseOffsetOffset) { + Out << ", " << Thunk.Return.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.VCallOffsetOffset) { + Out << ", " << Thunk.This.VCallOffsetOffset; + Out << " vcall offset offset"; + } + } + + Out << '\n'; + } + + Out << '\n'; + + } + } +} + +} + +void CodeGenVTables::ComputeMethodVTableIndices(const CXXRecordDecl *RD) { + + // 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. + + int64_t CurrentIndex = 0; + + const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); + const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); + + if (PrimaryBase) { + assert(PrimaryBase->isDefinition() && + "Should have the definition decl of the primary base!"); + + // Since the record decl shares its vtable pointer with the primary base + // we need to start counting at the end of the primary base's vtable. + CurrentIndex = getNumVirtualFunctionPointers(PrimaryBase); + } + + // Collect all the primary bases, so we can check whether methods override + // a method from the base. + VTableBuilder::PrimaryBasesSetVectorTy PrimaryBases; + for (ASTRecordLayout::primary_base_info_iterator + I = Layout.primary_base_begin(), E = Layout.primary_base_end(); + I != E; ++I) + PrimaryBases.insert((*I).getBase()); + + const CXXDestructorDecl *ImplicitVirtualDtor = 0; + + for (CXXRecordDecl::method_iterator i = RD->method_begin(), + e = RD->method_end(); i != e; ++i) { + const CXXMethodDecl *MD = *i; + + // We only want virtual methods. + if (!MD->isVirtual()) + continue; + + // Check if this method overrides a method in the primary base. + if (const CXXMethodDecl *OverriddenMD = + FindNearestOverriddenMethod(MD, PrimaryBases)) { + // Check if converting from the return type of the method to the + // return type of the overridden method requires conversion. + if (ComputeReturnAdjustmentBaseOffset(CGM.getContext(), MD, + OverriddenMD).isEmpty()) { + // This index is shared between the index in the vtable of the primary + // base class. + if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { + const CXXDestructorDecl *OverriddenDD = + cast<CXXDestructorDecl>(OverriddenMD); + + // Add both the complete and deleting entries. + MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)] = + getMethodVTableIndex(GlobalDecl(OverriddenDD, Dtor_Complete)); + MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)] = + getMethodVTableIndex(GlobalDecl(OverriddenDD, Dtor_Deleting)); + } else { + MethodVTableIndices[MD] = getMethodVTableIndex(OverriddenMD); + } + + // We don't need to add an entry for this method. + continue; + } + } + + if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { + if (MD->isImplicit()) { + assert(!ImplicitVirtualDtor && + "Did already see an implicit virtual dtor!"); + ImplicitVirtualDtor = DD; + continue; + } + + // Add the complete dtor. + MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)] = CurrentIndex++; + + // Add the deleting dtor. + MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)] = CurrentIndex++; + } else { + // Add the entry. + MethodVTableIndices[MD] = CurrentIndex++; + } + } + + if (ImplicitVirtualDtor) { + // Itanium C++ ABI 2.5.2: + // If a class has an implicitly-defined virtual destructor, + // its entries come after the declared virtual function pointers. + + // Add the complete dtor. + MethodVTableIndices[GlobalDecl(ImplicitVirtualDtor, Dtor_Complete)] = + CurrentIndex++; + + // Add the deleting dtor. + MethodVTableIndices[GlobalDecl(ImplicitVirtualDtor, Dtor_Deleting)] = + CurrentIndex++; + } + + NumVirtualFunctionPointers[RD] = CurrentIndex; +} + +uint64_t CodeGenVTables::getNumVirtualFunctionPointers(const CXXRecordDecl *RD) { + llvm::DenseMap<const CXXRecordDecl *, uint64_t>::iterator I = + NumVirtualFunctionPointers.find(RD); + if (I != NumVirtualFunctionPointers.end()) + return I->second; + + ComputeMethodVTableIndices(RD); + + I = NumVirtualFunctionPointers.find(RD); + assert(I != NumVirtualFunctionPointers.end() && "Did not find entry!"); + return I->second; +} + +uint64_t CodeGenVTables::getMethodVTableIndex(GlobalDecl GD) { + MethodVTableIndicesTy::iterator I = MethodVTableIndices.find(GD); + if (I != MethodVTableIndices.end()) + return I->second; + + const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent(); + + ComputeMethodVTableIndices(RD); + + I = MethodVTableIndices.find(GD); + assert(I != MethodVTableIndices.end() && "Did not find index!"); + return I->second; +} + +int64_t CodeGenVTables::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, /*FinalOverriders=*/0, + BaseSubobject(RD, 0), + /*BaseIsVirtual=*/false, + /*OffsetInLayoutClass=*/0); + + for (VCallAndVBaseOffsetBuilder::VBaseOffsetOffsetsMapTy::const_iterator I = + Builder.getVBaseOffsetOffsets().begin(), + E = Builder.getVBaseOffsetOffsets().end(); I != E; ++I) { + // 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; +} + +uint64_t +CodeGenVTables::getAddressPoint(BaseSubobject Base, const CXXRecordDecl *RD) { + assert(AddressPoints.count(std::make_pair(RD, Base)) && + "Did not find address point!"); + + uint64_t AddressPoint = AddressPoints.lookup(std::make_pair(RD, Base)); + assert(AddressPoint && "Address point must not be zero!"); + + return AddressPoint; +} + +llvm::Constant *CodeGenModule::GetAddrOfThunk(GlobalDecl GD, + const ThunkInfo &Thunk) { + const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); + + // Compute the mangled name. + llvm::SmallString<256> Name; + if (const CXXDestructorDecl* DD = dyn_cast<CXXDestructorDecl>(MD)) + getMangleContext().mangleCXXDtorThunk(DD, GD.getDtorType(), Thunk.This, + Name); + else + getMangleContext().mangleThunk(MD, Thunk, Name); + + const llvm::Type *Ty = getTypes().GetFunctionTypeForVTable(MD); + return GetOrCreateLLVMFunction(Name, Ty, GlobalDecl()); +} + +static llvm::Value *PerformTypeAdjustment(CodeGenFunction &CGF, + llvm::Value *Ptr, + int64_t NonVirtualAdjustment, + int64_t VirtualAdjustment) { + if (!NonVirtualAdjustment && !VirtualAdjustment) + return Ptr; + + const llvm::Type *Int8PtrTy = + llvm::Type::getInt8PtrTy(CGF.getLLVMContext()); + + llvm::Value *V = CGF.Builder.CreateBitCast(Ptr, Int8PtrTy); + + if (NonVirtualAdjustment) { + // Do the non-virtual adjustment. + V = CGF.Builder.CreateConstInBoundsGEP1_64(V, NonVirtualAdjustment); + } + + if (VirtualAdjustment) { + const llvm::Type *PtrDiffTy = + CGF.ConvertType(CGF.getContext().getPointerDiffType()); + + // Do the virtual adjustment. + llvm::Value *VTablePtrPtr = + CGF.Builder.CreateBitCast(V, Int8PtrTy->getPointerTo()); + + llvm::Value *VTablePtr = CGF.Builder.CreateLoad(VTablePtrPtr); + + llvm::Value *OffsetPtr = + CGF.Builder.CreateConstInBoundsGEP1_64(VTablePtr, VirtualAdjustment); + + OffsetPtr = CGF.Builder.CreateBitCast(OffsetPtr, PtrDiffTy->getPointerTo()); + + // Load the adjustment offset from the vtable. + llvm::Value *Offset = CGF.Builder.CreateLoad(OffsetPtr); + + // Adjust our pointer. + V = CGF.Builder.CreateInBoundsGEP(V, Offset); + } + + // Cast back to the original type. + return CGF.Builder.CreateBitCast(V, Ptr->getType()); +} + +void CodeGenFunction::GenerateThunk(llvm::Function *Fn, GlobalDecl GD, + const ThunkInfo &Thunk) { + const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); + const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>(); + QualType ResultType = FPT->getResultType(); + QualType ThisType = MD->getThisType(getContext()); + + FunctionArgList FunctionArgs; + + // FIXME: It would be nice if more of this code could be shared with + // CodeGenFunction::GenerateCode. + + // Create the implicit 'this' parameter declaration. + CXXThisDecl = ImplicitParamDecl::Create(getContext(), 0, + MD->getLocation(), + &getContext().Idents.get("this"), + ThisType); + + // Add the 'this' parameter. + FunctionArgs.push_back(std::make_pair(CXXThisDecl, CXXThisDecl->getType())); + + // Add the rest of the parameters. + for (FunctionDecl::param_const_iterator I = MD->param_begin(), + E = MD->param_end(); I != E; ++I) { + ParmVarDecl *Param = *I; + + FunctionArgs.push_back(std::make_pair(Param, Param->getType())); + } + + StartFunction(GlobalDecl(), ResultType, Fn, FunctionArgs, SourceLocation()); + + // Adjust the 'this' pointer if necessary. + llvm::Value *AdjustedThisPtr = + PerformTypeAdjustment(*this, LoadCXXThis(), + Thunk.This.NonVirtual, + Thunk.This.VCallOffsetOffset); + + CallArgList CallArgs; + + // Add our adjusted 'this' pointer. + CallArgs.push_back(std::make_pair(RValue::get(AdjustedThisPtr), ThisType)); + + // Add the rest of the parameters. + for (FunctionDecl::param_const_iterator I = MD->param_begin(), + E = MD->param_end(); I != E; ++I) { + ParmVarDecl *Param = *I; + QualType ArgType = Param->getType(); + + // FIXME: Declaring a DeclRefExpr on the stack is kinda icky. + DeclRefExpr ArgExpr(Param, ArgType.getNonReferenceType(), SourceLocation()); + CallArgs.push_back(std::make_pair(EmitCallArg(&ArgExpr, ArgType), ArgType)); + } + + // Get our callee. + const llvm::Type *Ty = + CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(MD), + FPT->isVariadic()); + llvm::Value *Callee = CGM.GetAddrOfFunction(GD, Ty); + + const CGFunctionInfo &FnInfo = + CGM.getTypes().getFunctionInfo(ResultType, CallArgs, + FPT->getExtInfo()); + + // Now emit our call. + RValue RV = EmitCall(FnInfo, Callee, ReturnValueSlot(), CallArgs, MD); + + if (!Thunk.Return.isEmpty()) { + // Emit the return adjustment. + bool NullCheckValue = !ResultType->isReferenceType(); + + llvm::BasicBlock *AdjustNull = 0; + llvm::BasicBlock *AdjustNotNull = 0; + llvm::BasicBlock *AdjustEnd = 0; + + llvm::Value *ReturnValue = RV.getScalarVal(); + + if (NullCheckValue) { + AdjustNull = createBasicBlock("adjust.null"); + AdjustNotNull = createBasicBlock("adjust.notnull"); + AdjustEnd = createBasicBlock("adjust.end"); + + llvm::Value *IsNull = Builder.CreateIsNull(ReturnValue); + Builder.CreateCondBr(IsNull, AdjustNull, AdjustNotNull); + EmitBlock(AdjustNotNull); + } + + ReturnValue = PerformTypeAdjustment(*this, ReturnValue, + Thunk.Return.NonVirtual, + Thunk.Return.VBaseOffsetOffset); + + if (NullCheckValue) { + Builder.CreateBr(AdjustEnd); + EmitBlock(AdjustNull); + Builder.CreateBr(AdjustEnd); + EmitBlock(AdjustEnd); + + llvm::PHINode *PHI = Builder.CreatePHI(ReturnValue->getType()); + PHI->reserveOperandSpace(2); + PHI->addIncoming(ReturnValue, AdjustNotNull); + PHI->addIncoming(llvm::Constant::getNullValue(ReturnValue->getType()), + AdjustNull); + ReturnValue = PHI; + } + + RV = RValue::get(ReturnValue); + } + + if (!ResultType->isVoidType()) + EmitReturnOfRValue(RV, ResultType); + + FinishFunction(); + + // Destroy the 'this' declaration. + CXXThisDecl->Destroy(getContext()); + + // Set the right linkage. + Fn->setLinkage(CGM.getFunctionLinkage(MD)); + + // Set the right visibility. + CGM.setGlobalVisibility(Fn, MD); +} + +void CodeGenVTables::EmitThunk(GlobalDecl GD, const ThunkInfo &Thunk) +{ + llvm::Constant *Entry = CGM.GetAddrOfThunk(GD, Thunk); + const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); + + // Strip off a bitcast if we got one back. + if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Entry)) { + assert(CE->getOpcode() == llvm::Instruction::BitCast); + Entry = CE->getOperand(0); + } + + // There's already a declaration with the same name, check if it has the same + // type or if we need to replace it. + if (cast<llvm::GlobalValue>(Entry)->getType()->getElementType() != + CGM.getTypes().GetFunctionTypeForVTable(MD)) { + llvm::GlobalValue *OldThunkFn = cast<llvm::GlobalValue>(Entry); + + // If the types mismatch then we have to rewrite the definition. + assert(OldThunkFn->isDeclaration() && + "Shouldn't replace non-declaration"); + + // Remove the name from the old thunk function and get a new thunk. + OldThunkFn->setName(llvm::StringRef()); + Entry = CGM.GetAddrOfThunk(GD, Thunk); + + // If needed, replace the old thunk with a bitcast. + if (!OldThunkFn->use_empty()) { + llvm::Constant *NewPtrForOldDecl = + llvm::ConstantExpr::getBitCast(Entry, OldThunkFn->getType()); + OldThunkFn->replaceAllUsesWith(NewPtrForOldDecl); + } + + // Remove the old thunk. + OldThunkFn->eraseFromParent(); + } + + // Actually generate the thunk body. + llvm::Function *ThunkFn = cast<llvm::Function>(Entry); + CodeGenFunction(CGM).GenerateThunk(ThunkFn, GD, Thunk); +} + +void CodeGenVTables::EmitThunks(GlobalDecl GD) +{ + const CXXMethodDecl *MD = + cast<CXXMethodDecl>(GD.getDecl())->getCanonicalDecl(); + + // We don't need to generate thunks for the base destructor. + if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base) + return; + + const CXXRecordDecl *RD = MD->getParent(); + + // Compute VTable related info for this class. + ComputeVTableRelatedInformation(RD); + + ThunksMapTy::const_iterator I = Thunks.find(MD); + if (I == Thunks.end()) { + // We did not find a thunk for this method. + return; + } + + const ThunkInfoVectorTy &ThunkInfoVector = I->second; + for (unsigned I = 0, E = ThunkInfoVector.size(); I != E; ++I) + EmitThunk(GD, ThunkInfoVector[I]); +} + +void CodeGenVTables::ComputeVTableRelatedInformation(const CXXRecordDecl *RD) { + uint64_t *&LayoutData = VTableLayoutMap[RD]; + + // Check if we've computed this information before. + if (LayoutData) + return; + + VTableBuilder Builder(*this, RD, 0, /*MostDerivedClassIsVirtual=*/0, RD); + + // Add the VTable layout. + uint64_t NumVTableComponents = Builder.getNumVTableComponents(); + LayoutData = new uint64_t[NumVTableComponents + 1]; + + // Store the number of components. + LayoutData[0] = NumVTableComponents; + + // Store the components. + std::copy(Builder.vtable_components_data_begin(), + Builder.vtable_components_data_end(), + &LayoutData[1]); + + // Add the known thunks. + Thunks.insert(Builder.thunks_begin(), Builder.thunks_end()); + + // Add the thunks needed in this vtable. + assert(!VTableThunksMap.count(RD) && + "Thunks already exists for this vtable!"); + + VTableThunksTy &VTableThunks = VTableThunksMap[RD]; + VTableThunks.append(Builder.vtable_thunks_begin(), + Builder.vtable_thunks_end()); + + // Sort them. + std::sort(VTableThunks.begin(), VTableThunks.end()); + + // Add the address points. + for (VTableBuilder::AddressPointsMapTy::const_iterator I = + Builder.address_points_begin(), E = Builder.address_points_end(); + I != E; ++I) { + + uint64_t &AddressPoint = AddressPoints[std::make_pair(RD, I->first)]; + + // Check if we already have the address points for this base. + assert(!AddressPoint && "Address point already exists for this base!"); + + AddressPoint = I->second; + } + + // 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 RecordType *VBaseRT = + RD->vbases_begin()->getType()->getAs<RecordType>(); + const CXXRecordDecl *VBase = cast<CXXRecordDecl>(VBaseRT->getDecl()); + + if (VirtualBaseClassOffsetOffsets.count(std::make_pair(RD, VBase))) + return; + + for (VTableBuilder::VBaseOffsetOffsetsMapTy::const_iterator I = + Builder.getVBaseOffsetOffsets().begin(), + E = Builder.getVBaseOffsetOffsets().end(); I != E; ++I) { + // Insert all types. + ClassPairTy ClassPair(RD, I->first); + + VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I->second)); + } +} + +llvm::Constant * +CodeGenVTables::CreateVTableInitializer(const CXXRecordDecl *RD, + const uint64_t *Components, + unsigned NumComponents, + const VTableThunksTy &VTableThunks) { + llvm::SmallVector<llvm::Constant *, 64> Inits; + + const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext()); + + const llvm::Type *PtrDiffTy = + CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType()); + + QualType ClassType = CGM.getContext().getTagDeclType(RD); + llvm::Constant *RTTI = CGM.GetAddrOfRTTIDescriptor(ClassType); + + unsigned NextVTableThunkIndex = 0; + + llvm::Constant* PureVirtualFn = 0; + + for (unsigned I = 0; I != NumComponents; ++I) { + VTableComponent Component = + VTableComponent::getFromOpaqueInteger(Components[I]); + + llvm::Constant *Init = 0; + + switch (Component.getKind()) { + case VTableComponent::CK_VCallOffset: + Init = llvm::ConstantInt::get(PtrDiffTy, Component.getVCallOffset()); + Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy); + break; + case VTableComponent::CK_VBaseOffset: + Init = llvm::ConstantInt::get(PtrDiffTy, Component.getVBaseOffset()); + Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy); + break; + case VTableComponent::CK_OffsetToTop: + Init = llvm::ConstantInt::get(PtrDiffTy, Component.getOffsetToTop()); + Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy); + break; + case VTableComponent::CK_RTTI: + Init = llvm::ConstantExpr::getBitCast(RTTI, Int8PtrTy); + break; + case VTableComponent::CK_FunctionPointer: + case VTableComponent::CK_CompleteDtorPointer: + case VTableComponent::CK_DeletingDtorPointer: { + GlobalDecl GD; + + // Get the right global decl. + switch (Component.getKind()) { + default: + llvm_unreachable("Unexpected vtable component kind"); + case VTableComponent::CK_FunctionPointer: + GD = Component.getFunctionDecl(); + break; + case VTableComponent::CK_CompleteDtorPointer: + GD = GlobalDecl(Component.getDestructorDecl(), Dtor_Complete); + break; + case VTableComponent::CK_DeletingDtorPointer: + GD = GlobalDecl(Component.getDestructorDecl(), Dtor_Deleting); + break; + } + + if (cast<CXXMethodDecl>(GD.getDecl())->isPure()) { + // We have a pure virtual member function. + if (!PureVirtualFn) { + const llvm::FunctionType *Ty = + llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()), + /*isVarArg=*/false); + PureVirtualFn = + CGM.CreateRuntimeFunction(Ty, "__cxa_pure_virtual"); + PureVirtualFn = llvm::ConstantExpr::getBitCast(PureVirtualFn, + Int8PtrTy); + } + + Init = PureVirtualFn; + } else { + // Check if we should use a thunk. + if (NextVTableThunkIndex < VTableThunks.size() && + VTableThunks[NextVTableThunkIndex].first == I) { + const ThunkInfo &Thunk = VTableThunks[NextVTableThunkIndex].second; + + Init = CGM.GetAddrOfThunk(GD, Thunk); + + NextVTableThunkIndex++; + } else { + const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); + const llvm::Type *Ty = CGM.getTypes().GetFunctionTypeForVTable(MD); + + Init = CGM.GetAddrOfFunction(GD, Ty); + } + + Init = llvm::ConstantExpr::getBitCast(Init, Int8PtrTy); + } + break; + } + + case VTableComponent::CK_UnusedFunctionPointer: + Init = llvm::ConstantExpr::getNullValue(Int8PtrTy); + break; + }; + + Inits.push_back(Init); + } + + llvm::ArrayType *ArrayType = llvm::ArrayType::get(Int8PtrTy, NumComponents); + return llvm::ConstantArray::get(ArrayType, Inits.data(), Inits.size()); +} + +/// GetGlobalVariable - Will return a global variable of the given type. +/// If a variable with a different type already exists then a new variable +/// with the right type will be created. +/// FIXME: We should move this to CodeGenModule and rename it to something +/// better and then use it in CGVTT and CGRTTI. +static llvm::GlobalVariable * +GetGlobalVariable(llvm::Module &Module, llvm::StringRef Name, + const llvm::Type *Ty, + llvm::GlobalValue::LinkageTypes Linkage) { + + llvm::GlobalVariable *GV = Module.getNamedGlobal(Name); + llvm::GlobalVariable *OldGV = 0; + + if (GV) { + // Check if the variable has the right type. + if (GV->getType()->getElementType() == Ty) + return GV; + + assert(GV->isDeclaration() && "Declaration has wrong type!"); + + OldGV = GV; + } + + // Create a new variable. + GV = new llvm::GlobalVariable(Module, Ty, /*isConstant=*/true, + Linkage, 0, Name); + + if (OldGV) { + // Replace occurrences of the old variable if needed. + GV->takeName(OldGV); + + if (!OldGV->use_empty()) { + llvm::Constant *NewPtrForOldDecl = + llvm::ConstantExpr::getBitCast(GV, OldGV->getType()); + OldGV->replaceAllUsesWith(NewPtrForOldDecl); + } + + OldGV->eraseFromParent(); + } + + return GV; +} + +llvm::GlobalVariable *CodeGenVTables::GetAddrOfVTable(const CXXRecordDecl *RD) { + llvm::SmallString<256> OutName; + CGM.getMangleContext().mangleCXXVTable(RD, OutName); + llvm::StringRef Name = OutName.str(); + + ComputeVTableRelatedInformation(RD); + + const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext()); + llvm::ArrayType *ArrayType = + llvm::ArrayType::get(Int8PtrTy, getNumVTableComponents(RD)); + + return GetGlobalVariable(CGM.getModule(), Name, ArrayType, + llvm::GlobalValue::ExternalLinkage); +} + +void +CodeGenVTables::EmitVTableDefinition(llvm::GlobalVariable *VTable, + llvm::GlobalVariable::LinkageTypes Linkage, + const CXXRecordDecl *RD) { + // Dump the vtable layout if necessary. + if (CGM.getLangOptions().DumpVTableLayouts) { + VTableBuilder Builder(*this, RD, 0, /*MostDerivedClassIsVirtual=*/0, RD); + + Builder.dumpLayout(llvm::errs()); + } + + assert(VTableThunksMap.count(RD) && + "No thunk status for this record decl!"); + + const VTableThunksTy& Thunks = VTableThunksMap[RD]; + + // Create and set the initializer. + llvm::Constant *Init = + CreateVTableInitializer(RD, getVTableComponentsData(RD), + getNumVTableComponents(RD), Thunks); + VTable->setInitializer(Init); + + // Set the correct linkage. + VTable->setLinkage(Linkage); +} + +llvm::GlobalVariable * +CodeGenVTables::GenerateConstructionVTable(const CXXRecordDecl *RD, + const BaseSubobject &Base, + bool BaseIsVirtual, + VTableAddressPointsMapTy& AddressPoints) { + VTableBuilder Builder(*this, Base.getBase(), Base.getBaseOffset(), + /*MostDerivedClassIsVirtual=*/BaseIsVirtual, RD); + + // Dump the vtable layout if necessary. + if (CGM.getLangOptions().DumpVTableLayouts) + Builder.dumpLayout(llvm::errs()); + + // Add the address points. + AddressPoints.insert(Builder.address_points_begin(), + Builder.address_points_end()); + + // Get the mangled construction vtable name. + llvm::SmallString<256> OutName; + CGM.getMangleContext().mangleCXXCtorVTable(RD, Base.getBaseOffset() / 8, + Base.getBase(), OutName); + llvm::StringRef Name = OutName.str(); + + const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext()); + llvm::ArrayType *ArrayType = + llvm::ArrayType::get(Int8PtrTy, Builder.getNumVTableComponents()); + + // Create the variable that will hold the construction vtable. + llvm::GlobalVariable *VTable = + GetGlobalVariable(CGM.getModule(), Name, ArrayType, + llvm::GlobalValue::InternalLinkage); + + // Add the thunks. + VTableThunksTy VTableThunks; + VTableThunks.append(Builder.vtable_thunks_begin(), + Builder.vtable_thunks_end()); + + // Sort them. + std::sort(VTableThunks.begin(), VTableThunks.end()); + + // Create and set the initializer. + llvm::Constant *Init = + CreateVTableInitializer(Base.getBase(), + Builder.vtable_components_data_begin(), + Builder.getNumVTableComponents(), VTableThunks); + VTable->setInitializer(Init); + + return VTable; +} + +void +CodeGenVTables::GenerateClassData(llvm::GlobalVariable::LinkageTypes Linkage, + const CXXRecordDecl *RD) { + llvm::GlobalVariable *&VTable = VTables[RD]; + if (VTable) { + assert(VTable->getInitializer() && "VTable doesn't have a definition!"); + return; + } + + VTable = GetAddrOfVTable(RD); + EmitVTableDefinition(VTable, Linkage, RD); + + GenerateVTT(Linkage, /*GenerateDefinition=*/true, RD); + + // If this is the magic class __cxxabiv1::__fundamental_type_info, + // we will emit the typeinfo for the fundamental types. This is the + // same behaviour as GCC. + const DeclContext *DC = RD->getDeclContext(); + if (RD->getIdentifier() && + RD->getIdentifier()->isStr("__fundamental_type_info") && + isa<NamespaceDecl>(DC) && + cast<NamespaceDecl>(DC)->getIdentifier() && + cast<NamespaceDecl>(DC)->getIdentifier()->isStr("__cxxabiv1") && + DC->getParent()->isTranslationUnit()) + CGM.EmitFundamentalRTTIDescriptors(); +} + +void CodeGenVTables::EmitVTableRelatedData(GlobalDecl GD) { + const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); + const CXXRecordDecl *RD = MD->getParent(); + + // If the class doesn't have a vtable we don't need to emit one. + if (!RD->isDynamicClass()) + return; + + // Check if we need to emit thunks for this function. + if (MD->isVirtual()) + EmitThunks(GD); + + // Get the key function. + const CXXMethodDecl *KeyFunction = CGM.getContext().getKeyFunction(RD); + + TemplateSpecializationKind RDKind = RD->getTemplateSpecializationKind(); + TemplateSpecializationKind MDKind = MD->getTemplateSpecializationKind(); + + if (KeyFunction) { + // We don't have the right key function. + if (KeyFunction->getCanonicalDecl() != MD->getCanonicalDecl()) + return; + } else { + // If we have no key funcion and this is a explicit instantiation declaration, + // we will produce a vtable at the explicit instantiation. We don't need one + // here. + if (RDKind == clang::TSK_ExplicitInstantiationDeclaration) + return; + + // If this is an explicit instantiation of a method, we don't need a vtable. + // Since we have no key function, we will emit the vtable when we see + // a use, and just defining a function is not an use. + if (RDKind == TSK_ImplicitInstantiation && + MDKind == TSK_ExplicitInstantiationDefinition) + return; + } + + if (VTables.count(RD)) + return; + + if (RDKind == TSK_ImplicitInstantiation) + CGM.DeferredVTables.push_back(RD); + else + GenerateClassData(CGM.getVTableLinkage(RD), RD); +} |