Merge branch 'master' of ssh://bitbucket.org/czan/honours

1 files changed, 733 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
new file mode 100644
index 0000000..17a0537
--- /dev/null
+++ b/clang/lib/CodeGen/CGVTables.cpp
@@ -0,0 +1,733 @@
+//===--- 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 "CGCXXABI.h"
+#include "clang/AST/CXXInheritance.h"
+#include "clang/AST/RecordLayout.h"
+#include "clang/Frontend/CodeGenOptions.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Transforms/Utils/Cloning.h"
+#include <algorithm>
+#include <cstdio>
+
+using namespace clang;
+using namespace CodeGen;
+
+CodeGenVTables::CodeGenVTables(CodeGenModule &CGM)
+  : CGM(CGM), VTContext(CGM.getContext()) { }
+
+bool CodeGenVTables::ShouldEmitVTableInThisTU(const CXXRecordDecl *RD) {
+  assert(RD->isDynamicClass() && "Non dynamic classes have no VTable.");
+
+  TemplateSpecializationKind TSK = RD->getTemplateSpecializationKind();
+  if (TSK == TSK_ExplicitInstantiationDeclaration)
+    return false;
+
+  const CXXMethodDecl *KeyFunction = CGM.getContext().getKeyFunction(RD);
+  if (!KeyFunction)
+    return true;
+
+  // Itanium C++ ABI, 5.2.6 Instantiated Templates:
+  //    An instantiation of a class template requires:
+  //        - In the object where instantiated, the virtual table...
+  if (TSK == TSK_ImplicitInstantiation ||
+      TSK == TSK_ExplicitInstantiationDefinition)
+    return true;
+
+  // If we're building with optimization, we always emit VTables since that
+  // allows for virtual function calls to be devirtualized.
+  // (We don't want to do this in -fapple-kext mode however).
+  if (CGM.getCodeGenOpts().OptimizationLevel && !CGM.getLangOpts().AppleKext)
+    return true;
+
+  return KeyFunction->hasBody();
+}
+
+llvm::Constant *CodeGenModule::GetAddrOfThunk(GlobalDecl GD, 
+                                              const ThunkInfo &Thunk) {
+  const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
+
+  // Compute the mangled name.
+  SmallString<256> Name;
+  llvm::raw_svector_ostream Out(Name);
+  if (const CXXDestructorDecl* DD = dyn_cast<CXXDestructorDecl>(MD))
+    getCXXABI().getMangleContext().mangleCXXDtorThunk(DD, GD.getDtorType(),
+                                                      Thunk.This, Out);
+  else
+    getCXXABI().getMangleContext().mangleThunk(MD, Thunk, Out);
+  Out.flush();
+
+  llvm::Type *Ty = getTypes().GetFunctionTypeForVTable(GD);
+  return GetOrCreateLLVMFunction(Name, Ty, GD, /*ForVTable=*/true);
+}
+
+static llvm::Value *PerformTypeAdjustment(CodeGenFunction &CGF,
+                                          llvm::Value *Ptr,
+                                          int64_t NonVirtualAdjustment,
+                                          int64_t VirtualAdjustment) {
+  if (!NonVirtualAdjustment && !VirtualAdjustment)
+    return Ptr;
+
+  llvm::Type *Int8PtrTy = CGF.Int8PtrTy;
+  llvm::Value *V = CGF.Builder.CreateBitCast(Ptr, Int8PtrTy);
+
+  if (NonVirtualAdjustment) {
+    // Do the non-virtual adjustment.
+    V = CGF.Builder.CreateConstInBoundsGEP1_64(V, NonVirtualAdjustment);
+  }
+
+  if (VirtualAdjustment) {
+    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());
+}
+
+static void setThunkVisibility(CodeGenModule &CGM, const CXXMethodDecl *MD,
+                               const ThunkInfo &Thunk, llvm::Function *Fn) {
+  CGM.setGlobalVisibility(Fn, MD);
+
+  if (!CGM.getCodeGenOpts().HiddenWeakVTables)
+    return;
+
+  // If the thunk has weak/linkonce linkage, but the function must be
+  // emitted in every translation unit that references it, then we can
+  // emit its thunks with hidden visibility, since its thunks must be
+  // emitted when the function is.
+
+  // This follows CodeGenModule::setTypeVisibility; see the comments
+  // there for explanation.
+
+  if ((Fn->getLinkage() != llvm::GlobalVariable::LinkOnceODRLinkage &&
+       Fn->getLinkage() != llvm::GlobalVariable::WeakODRLinkage) ||
+      Fn->getVisibility() != llvm::GlobalVariable::DefaultVisibility)
+    return;
+
+  if (MD->getExplicitVisibility())
+    return;
+
+  switch (MD->getTemplateSpecializationKind()) {
+  case TSK_ExplicitInstantiationDefinition:
+  case TSK_ExplicitInstantiationDeclaration:
+    return;
+
+  case TSK_Undeclared:
+    break;
+
+  case TSK_ExplicitSpecialization:
+  case TSK_ImplicitInstantiation:
+    if (!CGM.getCodeGenOpts().HiddenWeakTemplateVTables)
+      return;
+    break;
+  }
+
+  // If there's an explicit definition, and that definition is
+  // out-of-line, then we can't assume that all users will have a
+  // definition to emit.
+  const FunctionDecl *Def = 0;
+  if (MD->hasBody(Def) && Def->isOutOfLine())
+    return;
+
+  Fn->setVisibility(llvm::GlobalValue::HiddenVisibility);
+}
+
+#ifndef NDEBUG
+static bool similar(const ABIArgInfo &infoL, CanQualType typeL,
+                    const ABIArgInfo &infoR, CanQualType typeR) {
+  return (infoL.getKind() == infoR.getKind() &&
+          (typeL == typeR ||
+           (isa<PointerType>(typeL) && isa<PointerType>(typeR)) ||
+           (isa<ReferenceType>(typeL) && isa<ReferenceType>(typeR))));
+}
+#endif
+
+static RValue PerformReturnAdjustment(CodeGenFunction &CGF,
+                                      QualType ResultType, RValue RV,
+                                      const ThunkInfo &Thunk) {
+  // 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 = CGF.createBasicBlock("adjust.null");
+    AdjustNotNull = CGF.createBasicBlock("adjust.notnull");
+    AdjustEnd = CGF.createBasicBlock("adjust.end");
+  
+    llvm::Value *IsNull = CGF.Builder.CreateIsNull(ReturnValue);
+    CGF.Builder.CreateCondBr(IsNull, AdjustNull, AdjustNotNull);
+    CGF.EmitBlock(AdjustNotNull);
+  }
+  
+  ReturnValue = PerformTypeAdjustment(CGF, ReturnValue, 
+                                      Thunk.Return.NonVirtual, 
+                                      Thunk.Return.VBaseOffsetOffset);
+  
+  if (NullCheckValue) {
+    CGF.Builder.CreateBr(AdjustEnd);
+    CGF.EmitBlock(AdjustNull);
+    CGF.Builder.CreateBr(AdjustEnd);
+    CGF.EmitBlock(AdjustEnd);
+  
+    llvm::PHINode *PHI = CGF.Builder.CreatePHI(ReturnValue->getType(), 2);
+    PHI->addIncoming(ReturnValue, AdjustNotNull);
+    PHI->addIncoming(llvm::Constant::getNullValue(ReturnValue->getType()), 
+                     AdjustNull);
+    ReturnValue = PHI;
+  }
+  
+  return RValue::get(ReturnValue);
+}
+
+// This function does roughly the same thing as GenerateThunk, but in a
+// very different way, so that va_start and va_end work correctly.
+// FIXME: This function assumes "this" is the first non-sret LLVM argument of
+//        a function, and that there is an alloca built in the entry block
+//        for all accesses to "this".
+// FIXME: This function assumes there is only one "ret" statement per function.
+// FIXME: Cloning isn't correct in the presence of indirect goto!
+// FIXME: This implementation of thunks bloats codesize by duplicating the
+//        function definition.  There are alternatives:
+//        1. Add some sort of stub support to LLVM for cases where we can
+//           do a this adjustment, then a sibcall.
+//        2. We could transform the definition to take a va_list instead of an
+//           actual variable argument list, then have the thunks (including a
+//           no-op thunk for the regular definition) call va_start/va_end.
+//           There's a bit of per-call overhead for this solution, but it's
+//           better for codesize if the definition is long.
+void CodeGenFunction::GenerateVarArgsThunk(
+                                      llvm::Function *Fn,
+                                      const CGFunctionInfo &FnInfo,
+                                      GlobalDecl GD, const ThunkInfo &Thunk) {
+  const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
+  const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
+  QualType ResultType = FPT->getResultType();
+
+  // Get the original function
+  assert(FnInfo.isVariadic());
+  llvm::Type *Ty = CGM.getTypes().GetFunctionType(FnInfo);
+  llvm::Value *Callee = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true);
+  llvm::Function *BaseFn = cast<llvm::Function>(Callee);
+
+  // Clone to thunk.
+  llvm::Function *NewFn = llvm::CloneFunction(BaseFn);
+  CGM.getModule().getFunctionList().push_back(NewFn);
+  Fn->replaceAllUsesWith(NewFn);
+  NewFn->takeName(Fn);
+  Fn->eraseFromParent();
+  Fn = NewFn;
+
+  // "Initialize" CGF (minimally).
+  CurFn = Fn;
+
+  // Get the "this" value
+  llvm::Function::arg_iterator AI = Fn->arg_begin();
+  if (CGM.ReturnTypeUsesSRet(FnInfo))
+    ++AI;
+
+  // Find the first store of "this", which will be to the alloca associated
+  // with "this".
+  llvm::Value *ThisPtr = &*AI;
+  llvm::BasicBlock *EntryBB = Fn->begin();
+  llvm::Instruction *ThisStore = 0;
+  for (llvm::BasicBlock::iterator I = EntryBB->begin(), E = EntryBB->end();
+       I != E; I++) {
+    if (isa<llvm::StoreInst>(I) && I->getOperand(0) == ThisPtr) {
+      ThisStore = cast<llvm::StoreInst>(I);
+      break;
+    }
+  }
+  assert(ThisStore && "Store of this should be in entry block?");
+  // Adjust "this", if necessary.
+  Builder.SetInsertPoint(ThisStore);
+  llvm::Value *AdjustedThisPtr = 
+    PerformTypeAdjustment(*this, ThisPtr, 
+                          Thunk.This.NonVirtual, 
+                          Thunk.This.VCallOffsetOffset);
+  ThisStore->setOperand(0, AdjustedThisPtr);
+
+  if (!Thunk.Return.isEmpty()) {
+    // Fix up the returned value, if necessary.
+    for (llvm::Function::iterator I = Fn->begin(), E = Fn->end(); I != E; I++) {
+      llvm::Instruction *T = I->getTerminator();
+      if (isa<llvm::ReturnInst>(T)) {
+        RValue RV = RValue::get(T->getOperand(0));
+        T->eraseFromParent();
+        Builder.SetInsertPoint(&*I);
+        RV = PerformReturnAdjustment(*this, ResultType, RV, Thunk);
+        Builder.CreateRet(RV.getScalarVal());
+        break;
+      }
+    }
+  }
+}
+
+void CodeGenFunction::GenerateThunk(llvm::Function *Fn,
+                                    const CGFunctionInfo &FnInfo,
+                                    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.
+  CurGD = GD;
+  CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResultType, FunctionArgs);
+
+  // 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(Param);
+  }
+  
+  StartFunction(GlobalDecl(), ResultType, Fn, FnInfo, FunctionArgs,
+                SourceLocation());
+
+  CGM.getCXXABI().EmitInstanceFunctionProlog(*this);
+  CXXThisValue = CXXABIThisValue;
+
+  // 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.add(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;
+    EmitDelegateCallArg(CallArgs, param);
+  }
+
+  // Get our callee.
+  llvm::Type *Ty =
+    CGM.getTypes().GetFunctionType(CGM.getTypes().arrangeGlobalDeclaration(GD));
+  llvm::Value *Callee = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true);
+
+#ifndef NDEBUG
+  const CGFunctionInfo &CallFnInfo = 
+    CGM.getTypes().arrangeFunctionCall(ResultType, CallArgs, FPT->getExtInfo(),
+                                       RequiredArgs::forPrototypePlus(FPT, 1));
+  assert(CallFnInfo.getRegParm() == FnInfo.getRegParm() &&
+         CallFnInfo.isNoReturn() == FnInfo.isNoReturn() &&
+         CallFnInfo.getCallingConvention() == FnInfo.getCallingConvention());
+  assert(similar(CallFnInfo.getReturnInfo(), CallFnInfo.getReturnType(),
+                 FnInfo.getReturnInfo(), FnInfo.getReturnType()));
+  assert(CallFnInfo.arg_size() == FnInfo.arg_size());
+  for (unsigned i = 0, e = FnInfo.arg_size(); i != e; ++i)
+    assert(similar(CallFnInfo.arg_begin()[i].info,
+                   CallFnInfo.arg_begin()[i].type,
+                   FnInfo.arg_begin()[i].info, FnInfo.arg_begin()[i].type));
+#endif
+  
+  // Determine whether we have a return value slot to use.
+  ReturnValueSlot Slot;
+  if (!ResultType->isVoidType() &&
+      FnInfo.getReturnInfo().getKind() == ABIArgInfo::Indirect &&
+      hasAggregateLLVMType(CurFnInfo->getReturnType()))
+    Slot = ReturnValueSlot(ReturnValue, ResultType.isVolatileQualified());
+  
+  // Now emit our call.
+  RValue RV = EmitCall(FnInfo, Callee, Slot, CallArgs, MD);
+  
+  if (!Thunk.Return.isEmpty())
+    RV = PerformReturnAdjustment(*this, ResultType, RV, Thunk);
+
+  if (!ResultType->isVoidType() && Slot.isNull())
+    CGM.getCXXABI().EmitReturnFromThunk(*this, RV, ResultType);
+
+  FinishFunction();
+
+  // Set the right linkage.
+  CGM.setFunctionLinkage(MD, Fn);
+  
+  // Set the right visibility.
+  setThunkVisibility(CGM, MD, Thunk, Fn);
+}
+
+void CodeGenVTables::EmitThunk(GlobalDecl GD, const ThunkInfo &Thunk, 
+                               bool UseAvailableExternallyLinkage)
+{
+  const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeGlobalDeclaration(GD);
+
+  // FIXME: re-use FnInfo in this computation.
+  llvm::Constant *Entry = CGM.GetAddrOfThunk(GD, Thunk);
+  
+  // 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(GD)) {
+    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(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();
+  }
+
+  llvm::Function *ThunkFn = cast<llvm::Function>(Entry);
+
+  if (!ThunkFn->isDeclaration()) {
+    if (UseAvailableExternallyLinkage) {
+      // There is already a thunk emitted for this function, do nothing.
+      return;
+    }
+
+    // If a function has a body, it should have available_externally linkage.
+    assert(ThunkFn->hasAvailableExternallyLinkage() &&
+           "Function should have available_externally linkage!");
+
+    // Change the linkage.
+    CGM.setFunctionLinkage(cast<CXXMethodDecl>(GD.getDecl()), ThunkFn);
+    return;
+  }
+
+  if (ThunkFn->isVarArg()) {
+    // Varargs thunks are special; we can't just generate a call because
+    // we can't copy the varargs.  Our implementation is rather
+    // expensive/sucky at the moment, so don't generate the thunk unless
+    // we have to.
+    // FIXME: Do something better here; GenerateVarArgsThunk is extremely ugly.
+    if (!UseAvailableExternallyLinkage)
+      CodeGenFunction(CGM).GenerateVarArgsThunk(ThunkFn, FnInfo, GD, Thunk);
+  } else {
+    // Normal thunk body generation.
+    CodeGenFunction(CGM).GenerateThunk(ThunkFn, FnInfo, GD, Thunk);
+  }
+
+  if (UseAvailableExternallyLinkage)
+    ThunkFn->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage);
+}
+
+void CodeGenVTables::MaybeEmitThunkAvailableExternally(GlobalDecl GD,
+                                                       const ThunkInfo &Thunk) {
+  // We only want to do this when building with optimizations.
+  if (!CGM.getCodeGenOpts().OptimizationLevel)
+    return;
+
+  // We can't emit thunks for member functions with incomplete types.
+  const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
+  if (!CGM.getTypes().isFuncTypeConvertible(
+                                cast<FunctionType>(MD->getType().getTypePtr())))
+    return;
+
+  EmitThunk(GD, Thunk, /*UseAvailableExternallyLinkage=*/true);
+}
+
+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 VTableContext::ThunkInfoVectorTy *ThunkInfoVector =
+    VTContext.getThunkInfo(MD);
+  if (!ThunkInfoVector)
+    return;
+
+  for (unsigned I = 0, E = ThunkInfoVector->size(); I != E; ++I)
+    EmitThunk(GD, (*ThunkInfoVector)[I],
+              /*UseAvailableExternallyLinkage=*/false);
+}
+
+llvm::Constant *
+CodeGenVTables::CreateVTableInitializer(const CXXRecordDecl *RD,
+                                        const VTableComponent *Components, 
+                                        unsigned NumComponents,
+                                const VTableLayout::VTableThunkTy *VTableThunks,
+                                        unsigned NumVTableThunks) {
+  SmallVector<llvm::Constant *, 64> Inits;
+
+  llvm::Type *Int8PtrTy = CGM.Int8PtrTy;
+  
+  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 = Components[I];
+
+    llvm::Constant *Init = 0;
+
+    switch (Component.getKind()) {
+    case VTableComponent::CK_VCallOffset:
+      Init = llvm::ConstantInt::get(PtrDiffTy, 
+                                    Component.getVCallOffset().getQuantity());
+      Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy);
+      break;
+    case VTableComponent::CK_VBaseOffset:
+      Init = llvm::ConstantInt::get(PtrDiffTy, 
+                                    Component.getVBaseOffset().getQuantity());
+      Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy);
+      break;
+    case VTableComponent::CK_OffsetToTop:
+      Init = llvm::ConstantInt::get(PtrDiffTy, 
+                                    Component.getOffsetToTop().getQuantity());
+      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) {
+          llvm::FunctionType *Ty = 
+            llvm::FunctionType::get(CGM.VoidTy, /*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 < NumVTableThunks &&
+            VTableThunks[NextVTableThunkIndex].first == I) {
+          const ThunkInfo &Thunk = VTableThunks[NextVTableThunkIndex].second;
+        
+          MaybeEmitThunkAvailableExternally(GD, Thunk);
+          Init = CGM.GetAddrOfThunk(GD, Thunk);
+
+          NextVTableThunkIndex++;
+        } else {
+          llvm::Type *Ty = CGM.getTypes().GetFunctionTypeForVTable(GD);
+        
+          Init = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true);
+        }
+
+        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);
+}
+
+llvm::GlobalVariable *CodeGenVTables::GetAddrOfVTable(const CXXRecordDecl *RD) {
+  llvm::GlobalVariable *&VTable = VTables[RD];
+  if (VTable)
+    return VTable;
+
+  // We may need to generate a definition for this vtable.
+  if (ShouldEmitVTableInThisTU(RD))
+    CGM.DeferredVTables.push_back(RD);
+
+  SmallString<256> OutName;
+  llvm::raw_svector_ostream Out(OutName);
+  CGM.getCXXABI().getMangleContext().mangleCXXVTable(RD, Out);
+  Out.flush();
+  StringRef Name = OutName.str();
+
+  llvm::ArrayType *ArrayType = 
+    llvm::ArrayType::get(CGM.Int8PtrTy,
+                        VTContext.getVTableLayout(RD).getNumVTableComponents());
+
+  VTable =
+    CGM.CreateOrReplaceCXXRuntimeVariable(Name, ArrayType, 
+                                          llvm::GlobalValue::ExternalLinkage);
+  VTable->setUnnamedAddr(true);
+  return VTable;
+}
+
+void
+CodeGenVTables::EmitVTableDefinition(llvm::GlobalVariable *VTable,
+                                     llvm::GlobalVariable::LinkageTypes Linkage,
+                                     const CXXRecordDecl *RD) {
+  const VTableLayout &VTLayout = VTContext.getVTableLayout(RD);
+
+  // Create and set the initializer.
+  llvm::Constant *Init = 
+    CreateVTableInitializer(RD,
+                            VTLayout.vtable_component_begin(),
+                            VTLayout.getNumVTableComponents(),
+                            VTLayout.vtable_thunk_begin(),
+                            VTLayout.getNumVTableThunks());
+  VTable->setInitializer(Init);
+  
+  // Set the correct linkage.
+  VTable->setLinkage(Linkage);
+  
+  // Set the right visibility.
+  CGM.setTypeVisibility(VTable, RD, CodeGenModule::TVK_ForVTable);
+}
+
+llvm::GlobalVariable *
+CodeGenVTables::GenerateConstructionVTable(const CXXRecordDecl *RD, 
+                                      const BaseSubobject &Base, 
+                                      bool BaseIsVirtual, 
+                                   llvm::GlobalVariable::LinkageTypes Linkage,
+                                      VTableAddressPointsMapTy& AddressPoints) {
+  OwningPtr<VTableLayout> VTLayout(
+    VTContext.createConstructionVTableLayout(Base.getBase(),
+                                             Base.getBaseOffset(),
+                                             BaseIsVirtual, RD));
+
+  // Add the address points.
+  AddressPoints = VTLayout->getAddressPoints();
+
+  // Get the mangled construction vtable name.
+  SmallString<256> OutName;
+  llvm::raw_svector_ostream Out(OutName);
+  CGM.getCXXABI().getMangleContext().
+    mangleCXXCtorVTable(RD, Base.getBaseOffset().getQuantity(), Base.getBase(), 
+                        Out);
+  Out.flush();
+  StringRef Name = OutName.str();
+
+  llvm::ArrayType *ArrayType = 
+    llvm::ArrayType::get(CGM.Int8PtrTy, VTLayout->getNumVTableComponents());
+
+  // Create the variable that will hold the construction vtable.
+  llvm::GlobalVariable *VTable = 
+    CGM.CreateOrReplaceCXXRuntimeVariable(Name, ArrayType, Linkage);
+  CGM.setTypeVisibility(VTable, RD, CodeGenModule::TVK_ForConstructionVTable);
+
+  // V-tables are always unnamed_addr.
+  VTable->setUnnamedAddr(true);
+
+  // Create and set the initializer.
+  llvm::Constant *Init = 
+    CreateVTableInitializer(Base.getBase(), 
+                            VTLayout->vtable_component_begin(), 
+                            VTLayout->getNumVTableComponents(),
+                            VTLayout->vtable_thunk_begin(),
+                            VTLayout->getNumVTableThunks());
+  VTable->setInitializer(Init);
+  
+  return VTable;
+}
+
+void 
+CodeGenVTables::GenerateClassData(llvm::GlobalVariable::LinkageTypes Linkage,
+                                  const CXXRecordDecl *RD) {
+  llvm::GlobalVariable *VTable = GetAddrOfVTable(RD);
+  if (VTable->hasInitializer())
+    return;
+
+  EmitVTableDefinition(VTable, Linkage, RD);
+
+  if (RD->getNumVBases()) {
+    llvm::GlobalVariable *VTT = GetAddrOfVTT(RD);
+    EmitVTTDefinition(VTT, Linkage, 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();
+}