//===--- CGVTT.cpp - Emit LLVM Code for C++ VTTs --------------------------===// // // 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 VTTs (vtable tables). // //===----------------------------------------------------------------------===// #include "CodeGenModule.h" #include "CGCXXABI.h" #include "clang/AST/RecordLayout.h" #include "clang/AST/VTTBuilder.h" using namespace clang; using namespace CodeGen; static llvm::GlobalVariable * GetAddrOfVTTVTable(CodeGenVTables &CGVT, CodeGenModule &CGM, const CXXRecordDecl *MostDerivedClass, const VTTVTable &VTable, llvm::GlobalVariable::LinkageTypes Linkage, llvm::DenseMap<BaseSubobject, uint64_t> &AddressPoints) { if (VTable.getBase() == MostDerivedClass) { assert(VTable.getBaseOffset().isZero() && "Most derived class vtable must have a zero offset!"); // This is a regular vtable. return CGM.getCXXABI().getAddrOfVTable(MostDerivedClass, CharUnits()); } return CGVT.GenerateConstructionVTable(MostDerivedClass, VTable.getBaseSubobject(), VTable.isVirtual(), Linkage, AddressPoints); } void CodeGenVTables::EmitVTTDefinition(llvm::GlobalVariable *VTT, llvm::GlobalVariable::LinkageTypes Linkage, const CXXRecordDecl *RD) { VTTBuilder Builder(CGM.getContext(), RD, /*GenerateDefinition=*/true); llvm::Type *Int8PtrTy = CGM.Int8PtrTy, *Int64Ty = CGM.Int64Ty; llvm::ArrayType *ArrayType = llvm::ArrayType::get(Int8PtrTy, Builder.getVTTComponents().size()); SmallVector<llvm::GlobalVariable *, 8> VTables; SmallVector<VTableAddressPointsMapTy, 8> VTableAddressPoints; for (const VTTVTable *i = Builder.getVTTVTables().begin(), *e = Builder.getVTTVTables().end(); i != e; ++i) { VTableAddressPoints.push_back(VTableAddressPointsMapTy()); VTables.push_back(GetAddrOfVTTVTable(*this, CGM, RD, *i, Linkage, VTableAddressPoints.back())); } SmallVector<llvm::Constant *, 8> VTTComponents; for (const VTTComponent *i = Builder.getVTTComponents().begin(), *e = Builder.getVTTComponents().end(); i != e; ++i) { const VTTVTable &VTTVT = Builder.getVTTVTables()[i->VTableIndex]; llvm::GlobalVariable *VTable = VTables[i->VTableIndex]; uint64_t AddressPoint; if (VTTVT.getBase() == RD) { // Just get the address point for the regular vtable. AddressPoint = getItaniumVTableContext().getVTableLayout(RD).getAddressPoint( i->VTableBase); assert(AddressPoint != 0 && "Did not find vtable address point!"); } else { AddressPoint = VTableAddressPoints[i->VTableIndex].lookup(i->VTableBase); assert(AddressPoint != 0 && "Did not find ctor vtable address point!"); } llvm::Value *Idxs[] = { llvm::ConstantInt::get(Int64Ty, 0), llvm::ConstantInt::get(Int64Ty, AddressPoint) }; llvm::Constant *Init = llvm::ConstantExpr::getInBoundsGetElementPtr( VTable->getValueType(), VTable, Idxs); Init = llvm::ConstantExpr::getBitCast(Init, Int8PtrTy); VTTComponents.push_back(Init); } llvm::Constant *Init = llvm::ConstantArray::get(ArrayType, VTTComponents); VTT->setInitializer(Init); // Set the correct linkage. VTT->setLinkage(Linkage); if (CGM.supportsCOMDAT() && VTT->isWeakForLinker()) VTT->setComdat(CGM.getModule().getOrInsertComdat(VTT->getName())); // Set the right visibility. CGM.setGlobalVisibility(VTT, RD); } llvm::GlobalVariable *CodeGenVTables::GetAddrOfVTT(const CXXRecordDecl *RD) { assert(RD->getNumVBases() && "Only classes with virtual bases need a VTT"); SmallString<256> OutName; llvm::raw_svector_ostream Out(OutName); cast<ItaniumMangleContext>(CGM.getCXXABI().getMangleContext()) .mangleCXXVTT(RD, Out); StringRef Name = OutName.str(); // This will also defer the definition of the VTT. (void) CGM.getCXXABI().getAddrOfVTable(RD, CharUnits()); VTTBuilder Builder(CGM.getContext(), RD, /*GenerateDefinition=*/false); llvm::ArrayType *ArrayType = llvm::ArrayType::get(CGM.Int8PtrTy, Builder.getVTTComponents().size()); llvm::GlobalVariable *GV = CGM.CreateOrReplaceCXXRuntimeVariable(Name, ArrayType, llvm::GlobalValue::ExternalLinkage); GV->setUnnamedAddr(true); return GV; } uint64_t CodeGenVTables::getSubVTTIndex(const CXXRecordDecl *RD, BaseSubobject Base) { BaseSubobjectPairTy ClassSubobjectPair(RD, Base); SubVTTIndiciesMapTy::iterator I = SubVTTIndicies.find(ClassSubobjectPair); if (I != SubVTTIndicies.end()) return I->second; VTTBuilder Builder(CGM.getContext(), RD, /*GenerateDefinition=*/false); for (llvm::DenseMap<BaseSubobject, uint64_t>::const_iterator I = Builder.getSubVTTIndicies().begin(), E = Builder.getSubVTTIndicies().end(); I != E; ++I) { // Insert all indices. BaseSubobjectPairTy ClassSubobjectPair(RD, I->first); SubVTTIndicies.insert(std::make_pair(ClassSubobjectPair, I->second)); } I = SubVTTIndicies.find(ClassSubobjectPair); assert(I != SubVTTIndicies.end() && "Did not find index!"); return I->second; } uint64_t CodeGenVTables::getSecondaryVirtualPointerIndex(const CXXRecordDecl *RD, BaseSubobject Base) { SecondaryVirtualPointerIndicesMapTy::iterator I = SecondaryVirtualPointerIndices.find(std::make_pair(RD, Base)); if (I != SecondaryVirtualPointerIndices.end()) return I->second; VTTBuilder Builder(CGM.getContext(), RD, /*GenerateDefinition=*/false); // Insert all secondary vpointer indices. for (llvm::DenseMap<BaseSubobject, uint64_t>::const_iterator I = Builder.getSecondaryVirtualPointerIndices().begin(), E = Builder.getSecondaryVirtualPointerIndices().end(); I != E; ++I) { std::pair<const CXXRecordDecl *, BaseSubobject> Pair = std::make_pair(RD, I->first); SecondaryVirtualPointerIndices.insert(std::make_pair(Pair, I->second)); } I = SecondaryVirtualPointerIndices.find(std::make_pair(RD, Base)); assert(I != SecondaryVirtualPointerIndices.end() && "Did not find index!"); return I->second; }