CodeGenModule.cpp

    //   extern int test6();
    //   ...
    //   int test6() __attribute__((alias("test7")));
    //
    // Remove it and replace uses of it with the alias.
    GA->takeName(Entry);

    Entry->replaceAllUsesWith(llvm::ConstantExpr::getBitCast(GA,
                                                          Entry->getType()));
    Entry->eraseFromParent();
  } else {
    GA->setName(MangledName);
  }

  // Set attributes which are particular to an alias; this is a
  // specialization of the attributes which may be set on a global
  // variable/function.
  if (D->hasAttr<DLLExportAttr>()) {
    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
      // The dllexport attribute is ignored for undefined symbols.
      if (FD->hasBody())
        GA->setLinkage(llvm::Function::DLLExportLinkage);
    } else {
      GA->setLinkage(llvm::Function::DLLExportLinkage);
    }
  } else if (D->hasAttr<WeakAttr>() ||
             D->hasAttr<WeakRefAttr>() ||
             D->isWeakImported()) {
    GA->setLinkage(llvm::Function::WeakAnyLinkage);
  }

  SetCommonAttributes(D, GA);
}

llvm::Function *CodeGenModule::getIntrinsic(unsigned IID,
                                            ArrayRef<llvm::Type*> Tys) {
  return llvm::Intrinsic::getDeclaration(&getModule(), (llvm::Intrinsic::ID)IID,
                                         Tys);
}

static llvm::StringMapEntry<llvm::Constant*> &
GetConstantCFStringEntry(llvm::StringMap<llvm::Constant*> &Map,
                         const StringLiteral *Literal,
                         bool TargetIsLSB,
                         bool &IsUTF16,
                         unsigned &StringLength) {
  StringRef String = Literal->getString();
  unsigned NumBytes = String.size();

  // Check for simple case.
  if (!Literal->containsNonAsciiOrNull()) {
    StringLength = NumBytes;
    return Map.GetOrCreateValue(String);
  }

  // Otherwise, convert the UTF8 literals into a string of shorts.
  IsUTF16 = true;

  SmallVector<UTF16, 128> ToBuf(NumBytes + 1); // +1 for ending nulls.
  const UTF8 *FromPtr = (const UTF8 *)String.data();
  UTF16 *ToPtr = &ToBuf[0];

  (void)ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
                           &ToPtr, ToPtr + NumBytes,
                           strictConversion);

  // ConvertUTF8toUTF16 returns the length in ToPtr.
  StringLength = ToPtr - &ToBuf[0];

  // Add an explicit null.
  *ToPtr = 0;
  return Map.
    GetOrCreateValue(StringRef(reinterpret_cast<const char *>(ToBuf.data()),
                               (StringLength + 1) * 2));
}

static llvm::StringMapEntry<llvm::Constant*> &
GetConstantStringEntry(llvm::StringMap<llvm::Constant*> &Map,
                       const StringLiteral *Literal,
                       unsigned &StringLength) {
  StringRef String = Literal->getString();
  StringLength = String.size();
  return Map.GetOrCreateValue(String);
}

llvm::Constant *
CodeGenModule::GetAddrOfConstantCFString(const StringLiteral *Literal) {
  unsigned StringLength = 0;
  bool isUTF16 = false;
  llvm::StringMapEntry<llvm::Constant*> &Entry =
    GetConstantCFStringEntry(CFConstantStringMap, Literal,
                             getDataLayout().isLittleEndian(),
                             isUTF16, StringLength);

  if (llvm::Constant *C = Entry.getValue())
    return C;

  llvm::Constant *Zero = llvm::Constant::getNullValue(Int32Ty);
  llvm::Constant *Zeros[] = { Zero, Zero };

  // If we don't already have it, get __CFConstantStringClassReference.
  if (!CFConstantStringClassRef) {
    llvm::Type *Ty = getTypes().ConvertType(getContext().IntTy);
    Ty = llvm::ArrayType::get(Ty, 0);
    llvm::Constant *GV = CreateRuntimeVariable(Ty,
                                           "__CFConstantStringClassReference");
    // Decay array -> ptr
    CFConstantStringClassRef =
      llvm::ConstantExpr::getGetElementPtr(GV, Zeros);
  }

  QualType CFTy = getContext().getCFConstantStringType();

  llvm::StructType *STy =
    cast<llvm::StructType>(getTypes().ConvertType(CFTy));

  llvm::Constant *Fields[4];

  // Class pointer.
  Fields[0] = CFConstantStringClassRef;

  // Flags.
  llvm::Type *Ty = getTypes().ConvertType(getContext().UnsignedIntTy);
  Fields[1] = isUTF16 ? llvm::ConstantInt::get(Ty, 0x07d0) :
    llvm::ConstantInt::get(Ty, 0x07C8);

  // String pointer.
  llvm::Constant *C = 0;
  if (isUTF16) {
    ArrayRef<uint16_t> Arr =
      llvm::makeArrayRef<uint16_t>((uint16_t*)Entry.getKey().data(),
                                   Entry.getKey().size() / 2);
    C = llvm::ConstantDataArray::get(VMContext, Arr);
  } else {
    C = llvm::ConstantDataArray::getString(VMContext, Entry.getKey());
  }

  llvm::GlobalValue::LinkageTypes Linkage;
  if (isUTF16)
    // FIXME: why do utf strings get "_" labels instead of "L" labels?
    Linkage = llvm::GlobalValue::InternalLinkage;
  else
    // FIXME: With OS X ld 123.2 (xcode 4) and LTO we would get a linker error
    // when using private linkage. It is not clear if this is a bug in ld
    // or a reasonable new restriction.
    Linkage = llvm::GlobalValue::LinkerPrivateLinkage;
  
  // Note: -fwritable-strings doesn't make the backing store strings of
  // CFStrings writable. (See <rdar://problem/10657500>)
  llvm::GlobalVariable *GV =
    new llvm::GlobalVariable(getModule(), C->getType(), /*isConstant=*/true,
                             Linkage, C, ".str");
  GV->setUnnamedAddr(true);
  if (isUTF16) {
    CharUnits Align = getContext().getTypeAlignInChars(getContext().ShortTy);
    GV->setAlignment(Align.getQuantity());
  } else {
    CharUnits Align = getContext().getTypeAlignInChars(getContext().CharTy);
    GV->setAlignment(Align.getQuantity());
  }

  // String.
  Fields[2] = llvm::ConstantExpr::getGetElementPtr(GV, Zeros);

  if (isUTF16)
    // Cast the UTF16 string to the correct type.
    Fields[2] = llvm::ConstantExpr::getBitCast(Fields[2], Int8PtrTy);

  // String length.
  Ty = getTypes().ConvertType(getContext().LongTy);
  Fields[3] = llvm::ConstantInt::get(Ty, StringLength);

  // The struct.
  C = llvm::ConstantStruct::get(STy, Fields);
  GV = new llvm::GlobalVariable(getModule(), C->getType(), true,
                                llvm::GlobalVariable::PrivateLinkage, C,
                                "_unnamed_cfstring_");
  if (const char *Sect = getContext().getTargetInfo().getCFStringSection())
    GV->setSection(Sect);
  Entry.setValue(GV);

  return GV;
}

static RecordDecl *
CreateRecordDecl(const ASTContext &Ctx, RecordDecl::TagKind TK,
                 DeclContext *DC, IdentifierInfo *Id) {
  SourceLocation Loc;
  if (Ctx.getLangOpts().CPlusPlus)
    return CXXRecordDecl::Create(Ctx, TK, DC, Loc, Loc, Id);
  else
    return RecordDecl::Create(Ctx, TK, DC, Loc, Loc, Id);
}

llvm::Constant *
CodeGenModule::GetAddrOfConstantString(const StringLiteral *Literal) {
  unsigned StringLength = 0;
  llvm::StringMapEntry<llvm::Constant*> &Entry =
    GetConstantStringEntry(CFConstantStringMap, Literal, StringLength);
  
  if (llvm::Constant *C = Entry.getValue())
    return C;
  
  llvm::Constant *Zero = llvm::Constant::getNullValue(Int32Ty);
  llvm::Constant *Zeros[] = { Zero, Zero };
  
  // If we don't already have it, get _NSConstantStringClassReference.
  if (!ConstantStringClassRef) {
    std::string StringClass(getLangOpts().ObjCConstantStringClass);
    llvm::Type *Ty = getTypes().ConvertType(getContext().IntTy);
    llvm::Constant *GV;
    if (LangOpts.ObjCRuntime.isNonFragile()) {
      std::string str = 
        StringClass.empty() ? "OBJC_CLASS_$_NSConstantString" 
                            : "OBJC_CLASS_$_" + StringClass;
      GV = getObjCRuntime().GetClassGlobal(str);
      // Make sure the result is of the correct type.
      llvm::Type *PTy = llvm::PointerType::getUnqual(Ty);
      ConstantStringClassRef =
        llvm::ConstantExpr::getBitCast(GV, PTy);
    } else {
      std::string str =
        StringClass.empty() ? "_NSConstantStringClassReference"
                            : "_" + StringClass + "ClassReference";
      llvm::Type *PTy = llvm::ArrayType::get(Ty, 0);
      GV = CreateRuntimeVariable(PTy, str);
      // Decay array -> ptr
      ConstantStringClassRef = 
        llvm::ConstantExpr::getGetElementPtr(GV, Zeros);
    }
  }

  if (!NSConstantStringType) {
    // Construct the type for a constant NSString.
    RecordDecl *D = CreateRecordDecl(Context, TTK_Struct, 
                                     Context.getTranslationUnitDecl(),
                                   &Context.Idents.get("__builtin_NSString"));
    D->startDefinition();
      
    QualType FieldTypes[3];
    
    // const int *isa;
    FieldTypes[0] = Context.getPointerType(Context.IntTy.withConst());
    // const char *str;
    FieldTypes[1] = Context.getPointerType(Context.CharTy.withConst());
    // unsigned int length;
    FieldTypes[2] = Context.UnsignedIntTy;
    
    // Create fields
    for (unsigned i = 0; i < 3; ++i) {
      FieldDecl *Field = FieldDecl::Create(Context, D,
                                           SourceLocation(),
                                           SourceLocation(), 0,
                                           FieldTypes[i], /*TInfo=*/0,
                                           /*BitWidth=*/0,
                                           /*Mutable=*/false,
                                           ICIS_NoInit);
      Field->setAccess(AS_public);
      D->addDecl(Field);
    }
    
    D->completeDefinition();
    QualType NSTy = Context.getTagDeclType(D);
    NSConstantStringType = cast<llvm::StructType>(getTypes().ConvertType(NSTy));
  }
  
  llvm::Constant *Fields[3];
  
  // Class pointer.
  Fields[0] = ConstantStringClassRef;
  
  // String pointer.
  llvm::Constant *C =
    llvm::ConstantDataArray::getString(VMContext, Entry.getKey());
  
  llvm::GlobalValue::LinkageTypes Linkage;
  bool isConstant;
  Linkage = llvm::GlobalValue::PrivateLinkage;
  isConstant = !LangOpts.WritableStrings;
  
  llvm::GlobalVariable *GV =
  new llvm::GlobalVariable(getModule(), C->getType(), isConstant, Linkage, C,
                           ".str");
  GV->setUnnamedAddr(true);
  CharUnits Align = getContext().getTypeAlignInChars(getContext().CharTy);
  GV->setAlignment(Align.getQuantity());
  Fields[1] = llvm::ConstantExpr::getGetElementPtr(GV, Zeros);
  
  // String length.
  llvm::Type *Ty = getTypes().ConvertType(getContext().UnsignedIntTy);
  Fields[2] = llvm::ConstantInt::get(Ty, StringLength);
  
  // The struct.
  C = llvm::ConstantStruct::get(NSConstantStringType, Fields);
  GV = new llvm::GlobalVariable(getModule(), C->getType(), true,
                                llvm::GlobalVariable::PrivateLinkage, C,
                                "_unnamed_nsstring_");
  // FIXME. Fix section.
  if (const char *Sect = 
        LangOpts.ObjCRuntime.isNonFragile() 
          ? getContext().getTargetInfo().getNSStringNonFragileABISection() 
          : getContext().getTargetInfo().getNSStringSection())
    GV->setSection(Sect);
  Entry.setValue(GV);
  
  return GV;
}

QualType CodeGenModule::getObjCFastEnumerationStateType() {
  if (ObjCFastEnumerationStateType.isNull()) {
    RecordDecl *D = CreateRecordDecl(Context, TTK_Struct, 
                                     Context.getTranslationUnitDecl(),
                      &Context.Idents.get("__objcFastEnumerationState"));
    D->startDefinition();
    
    QualType FieldTypes[] = {
      Context.UnsignedLongTy,
      Context.getPointerType(Context.getObjCIdType()),
      Context.getPointerType(Context.UnsignedLongTy),
      Context.getConstantArrayType(Context.UnsignedLongTy,
                           llvm::APInt(32, 5), ArrayType::Normal, 0)
    };
    
    for (size_t i = 0; i < 4; ++i) {
      FieldDecl *Field = FieldDecl::Create(Context,
                                           D,
                                           SourceLocation(),
                                           SourceLocation(), 0,
                                           FieldTypes[i], /*TInfo=*/0,
                                           /*BitWidth=*/0,
                                           /*Mutable=*/false,
                                           ICIS_NoInit);
      Field->setAccess(AS_public);
      D->addDecl(Field);
    }
    
    D->completeDefinition();
    ObjCFastEnumerationStateType = Context.getTagDeclType(D);
  }
  
  return ObjCFastEnumerationStateType;
}

llvm::Constant *
CodeGenModule::GetConstantArrayFromStringLiteral(const StringLiteral *E) {
  assert(!E->getType()->isPointerType() && "Strings are always arrays");
  
  // Don't emit it as the address of the string, emit the string data itself
  // as an inline array.
  if (E->getCharByteWidth() == 1) {
    SmallString<64> Str(E->getString());

    // Resize the string to the right size, which is indicated by its type.
    const ConstantArrayType *CAT = Context.getAsConstantArrayType(E->getType());
    Str.resize(CAT->getSize().getZExtValue());
    return llvm::ConstantDataArray::getString(VMContext, Str, false);
  }
  
  llvm::ArrayType *AType =
    cast<llvm::ArrayType>(getTypes().ConvertType(E->getType()));
  llvm::Type *ElemTy = AType->getElementType();
  unsigned NumElements = AType->getNumElements();

  // Wide strings have either 2-byte or 4-byte elements.
  if (ElemTy->getPrimitiveSizeInBits() == 16) {
    SmallVector<uint16_t, 32> Elements;
    Elements.reserve(NumElements);

    for(unsigned i = 0, e = E->getLength(); i != e; ++i)
      Elements.push_back(E->getCodeUnit(i));
    Elements.resize(NumElements);
    return llvm::ConstantDataArray::get(VMContext, Elements);
  }
  
  assert(ElemTy->getPrimitiveSizeInBits() == 32);
  SmallVector<uint32_t, 32> Elements;
  Elements.reserve(NumElements);
  
  for(unsigned i = 0, e = E->getLength(); i != e; ++i)
    Elements.push_back(E->getCodeUnit(i));
  Elements.resize(NumElements);
  return llvm::ConstantDataArray::get(VMContext, Elements);
}

/// GetAddrOfConstantStringFromLiteral - Return a pointer to a
/// constant array for the given string literal.
llvm::Constant *
CodeGenModule::GetAddrOfConstantStringFromLiteral(const StringLiteral *S) {
  CharUnits Align = getContext().getTypeAlignInChars(S->getType());
  if (S->isAscii() || S->isUTF8()) {
    SmallString<64> Str(S->getString());
    
    // Resize the string to the right size, which is indicated by its type.
    const ConstantArrayType *CAT = Context.getAsConstantArrayType(S->getType());
    Str.resize(CAT->getSize().getZExtValue());
    return GetAddrOfConstantString(Str, /*GlobalName*/ 0, Align.getQuantity());
  }

  // FIXME: the following does not memoize wide strings.
  llvm::Constant *C = GetConstantArrayFromStringLiteral(S);
  llvm::GlobalVariable *GV =
    new llvm::GlobalVariable(getModule(),C->getType(),
                             !LangOpts.WritableStrings,
                             llvm::GlobalValue::PrivateLinkage,
                             C,".str");

  GV->setAlignment(Align.getQuantity());
  GV->setUnnamedAddr(true);
  return GV;
}

/// GetAddrOfConstantStringFromObjCEncode - Return a pointer to a constant
/// array for the given ObjCEncodeExpr node.
llvm::Constant *
CodeGenModule::GetAddrOfConstantStringFromObjCEncode(const ObjCEncodeExpr *E) {
  std::string Str;
  getContext().getObjCEncodingForType(E->getEncodedType(), Str);

  return GetAddrOfConstantCString(Str);
}


/// GenerateWritableString -- Creates storage for a string literal.
static llvm::GlobalVariable *GenerateStringLiteral(StringRef str,
                                             bool constant,
                                             CodeGenModule &CGM,
                                             const char *GlobalName,
                                             unsigned Alignment) {
  // Create Constant for this string literal. Don't add a '\0'.
  llvm::Constant *C =
      llvm::ConstantDataArray::getString(CGM.getLLVMContext(), str, false);

  // Create a global variable for this string
  llvm::GlobalVariable *GV =
    new llvm::GlobalVariable(CGM.getModule(), C->getType(), constant,
                             llvm::GlobalValue::PrivateLinkage,
                             C, GlobalName);
  GV->setAlignment(Alignment);
  GV->setUnnamedAddr(true);
  return GV;
}

/// GetAddrOfConstantString - Returns a pointer to a character array
/// containing the literal. This contents are exactly that of the
/// given string, i.e. it will not be null terminated automatically;
/// see GetAddrOfConstantCString. Note that whether the result is
/// actually a pointer to an LLVM constant depends on
/// Feature.WriteableStrings.
///
/// The result has pointer to array type.
llvm::Constant *CodeGenModule::GetAddrOfConstantString(StringRef Str,
                                                       const char *GlobalName,
                                                       unsigned Alignment) {
  // Get the default prefix if a name wasn't specified.
  if (!GlobalName)
    GlobalName = ".str";

  // Don't share any string literals if strings aren't constant.
  if (LangOpts.WritableStrings)
    return GenerateStringLiteral(Str, false, *this, GlobalName, Alignment);

  llvm::StringMapEntry<llvm::GlobalVariable *> &Entry =
    ConstantStringMap.GetOrCreateValue(Str);

  if (llvm::GlobalVariable *GV = Entry.getValue()) {
    if (Alignment > GV->getAlignment()) {
      GV->setAlignment(Alignment);
    }
    return GV;
  }

  // Create a global variable for this.
  llvm::GlobalVariable *GV = GenerateStringLiteral(Str, true, *this, GlobalName,
                                                   Alignment);
  Entry.setValue(GV);
  return GV;
}

/// GetAddrOfConstantCString - Returns a pointer to a character
/// array containing the literal and a terminating '\0'
/// character. The result has pointer to array type.
llvm::Constant *CodeGenModule::GetAddrOfConstantCString(const std::string &Str,
                                                        const char *GlobalName,
                                                        unsigned Alignment) {
  StringRef StrWithNull(Str.c_str(), Str.size() + 1);
  return GetAddrOfConstantString(StrWithNull, GlobalName, Alignment);
}

/// EmitObjCPropertyImplementations - Emit information for synthesized
/// properties for an implementation.
void CodeGenModule::EmitObjCPropertyImplementations(const
                                                    ObjCImplementationDecl *D) {
  for (ObjCImplementationDecl::propimpl_iterator
         i = D->propimpl_begin(), e = D->propimpl_end(); i != e; ++i) {
    ObjCPropertyImplDecl *PID = *i;

    // Dynamic is just for type-checking.
    if (PID->getPropertyImplementation() == ObjCPropertyImplDecl::Synthesize) {
      ObjCPropertyDecl *PD = PID->getPropertyDecl();

      // Determine which methods need to be implemented, some may have
      // been overridden. Note that ::isPropertyAccessor is not the method
      // we want, that just indicates if the decl came from a
      // property. What we want to know is if the method is defined in
      // this implementation.
      if (!D->getInstanceMethod(PD->getGetterName()))
        CodeGenFunction(*this).GenerateObjCGetter(
                                 const_cast<ObjCImplementationDecl *>(D), PID);
      if (!PD->isReadOnly() &&
          !D->getInstanceMethod(PD->getSetterName()))
        CodeGenFunction(*this).GenerateObjCSetter(
                                 const_cast<ObjCImplementationDecl *>(D), PID);
    }
  }
}

static bool needsDestructMethod(ObjCImplementationDecl *impl) {
  const ObjCInterfaceDecl *iface = impl->getClassInterface();
  for (const ObjCIvarDecl *ivar = iface->all_declared_ivar_begin();
       ivar; ivar = ivar->getNextIvar())
    if (ivar->getType().isDestructedType())
      return true;

  return false;
}

/// EmitObjCIvarInitializations - Emit information for ivar initialization
/// for an implementation.
void CodeGenModule::EmitObjCIvarInitializations(ObjCImplementationDecl *D) {
  // We might need a .cxx_destruct even if we don't have any ivar initializers.
  if (needsDestructMethod(D)) {
    IdentifierInfo *II = &getContext().Idents.get(".cxx_destruct");
    Selector cxxSelector = getContext().Selectors.getSelector(0, &II);
    ObjCMethodDecl *DTORMethod =
      ObjCMethodDecl::Create(getContext(), D->getLocation(), D->getLocation(),
                             cxxSelector, getContext().VoidTy, 0, D,
                             /*isInstance=*/true, /*isVariadic=*/false,
                          /*isPropertyAccessor=*/true, /*isImplicitlyDeclared=*/true,
                             /*isDefined=*/false, ObjCMethodDecl::Required);
    D->addInstanceMethod(DTORMethod);
    CodeGenFunction(*this).GenerateObjCCtorDtorMethod(D, DTORMethod, false);
    D->setHasDestructors(true);
  }

  // If the implementation doesn't have any ivar initializers, we don't need
  // a .cxx_construct.
  if (D->getNumIvarInitializers() == 0)
    return;
  
  IdentifierInfo *II = &getContext().Idents.get(".cxx_construct");
  Selector cxxSelector = getContext().Selectors.getSelector(0, &II);
  // The constructor returns 'self'.
  ObjCMethodDecl *CTORMethod = ObjCMethodDecl::Create(getContext(), 
                                                D->getLocation(),
                                                D->getLocation(),
                                                cxxSelector,
                                                getContext().getObjCIdType(), 0, 
                                                D, /*isInstance=*/true,
                                                /*isVariadic=*/false,
                                                /*isPropertyAccessor=*/true,
                                                /*isImplicitlyDeclared=*/true,
                                                /*isDefined=*/false,
                                                ObjCMethodDecl::Required);
  D->addInstanceMethod(CTORMethod);
  CodeGenFunction(*this).GenerateObjCCtorDtorMethod(D, CTORMethod, true);
  D->setHasNonZeroConstructors(true);
}

/// EmitNamespace - Emit all declarations in a namespace.
void CodeGenModule::EmitNamespace(const NamespaceDecl *ND) {
  for (RecordDecl::decl_iterator I = ND->decls_begin(), E = ND->decls_end();
       I != E; ++I)
    EmitTopLevelDecl(*I);
}

// EmitLinkageSpec - Emit all declarations in a linkage spec.
void CodeGenModule::EmitLinkageSpec(const LinkageSpecDecl *LSD) {
  if (LSD->getLanguage() != LinkageSpecDecl::lang_c &&
      LSD->getLanguage() != LinkageSpecDecl::lang_cxx) {
    ErrorUnsupported(LSD, "linkage spec");
    return;
  }

  for (RecordDecl::decl_iterator I = LSD->decls_begin(), E = LSD->decls_end();
       I != E; ++I) {
    if (ObjCImplDecl *OID = dyn_cast<ObjCImplDecl>(*I)) {
      for (ObjCContainerDecl::method_iterator M = OID->meth_begin(),
           MEnd = OID->meth_end();
           M != MEnd; ++M)
        EmitTopLevelDecl(*M);
    }
    EmitTopLevelDecl(*I);
  }
}

/// EmitTopLevelDecl - Emit code for a single top level declaration.
void CodeGenModule::EmitTopLevelDecl(Decl *D) {
  // If an error has occurred, stop code generation, but continue
  // parsing and semantic analysis (to ensure all warnings and errors
  // are emitted).
  if (Diags.hasErrorOccurred())
    return;

  // Ignore dependent declarations.
  if (D->getDeclContext() && D->getDeclContext()->isDependentContext())
    return;

  switch (D->getKind()) {
  case Decl::CXXConversion:
  case Decl::CXXMethod:
  case Decl::Function:
    // Skip function templates
    if (cast<FunctionDecl>(D)->getDescribedFunctionTemplate() ||
        cast<FunctionDecl>(D)->isLateTemplateParsed())
      return;

    EmitGlobal(cast<FunctionDecl>(D));
    break;
      
  case Decl::Var:
    EmitGlobal(cast<VarDecl>(D));
    break;

  // Indirect fields from global anonymous structs and unions can be
  // ignored; only the actual variable requires IR gen support.
  case Decl::IndirectField:
    break;

  // C++ Decls
  case Decl::Namespace:
    EmitNamespace(cast<NamespaceDecl>(D));
    break;
    // No code generation needed.
  case Decl::UsingShadow:
  case Decl::Using:
  case Decl::UsingDirective:
  case Decl::ClassTemplate:
  case Decl::FunctionTemplate:
  case Decl::TypeAliasTemplate:
  case Decl::NamespaceAlias:
  case Decl::Block:
  case Decl::Import:
    break;
  case Decl::CXXConstructor:
    // Skip function templates
    if (cast<FunctionDecl>(D)->getDescribedFunctionTemplate() ||
        cast<FunctionDecl>(D)->isLateTemplateParsed())
      return;
      
    EmitCXXConstructors(cast<CXXConstructorDecl>(D));
    break;
  case Decl::CXXDestructor:
    if (cast<FunctionDecl>(D)->isLateTemplateParsed())
      return;
    EmitCXXDestructors(cast<CXXDestructorDecl>(D));
    break;

  case Decl::StaticAssert:
    // Nothing to do.
    break;

  // Objective-C Decls

  // Forward declarations, no (immediate) code generation.
  case Decl::ObjCInterface:
  case Decl::ObjCCategory:
    break;

  case Decl::ObjCProtocol: {
    ObjCProtocolDecl *Proto = cast<ObjCProtocolDecl>(D);
    if (Proto->isThisDeclarationADefinition())
      ObjCRuntime->GenerateProtocol(Proto);
    break;
  }
      
  case Decl::ObjCCategoryImpl:
    // Categories have properties but don't support synthesize so we
    // can ignore them here.
    ObjCRuntime->GenerateCategory(cast<ObjCCategoryImplDecl>(D));
    break;

  case Decl::ObjCImplementation: {
    ObjCImplementationDecl *OMD = cast<ObjCImplementationDecl>(D);
    EmitObjCPropertyImplementations(OMD);
    EmitObjCIvarInitializations(OMD);
    ObjCRuntime->GenerateClass(OMD);
    // Emit global variable debug information.
    if (CGDebugInfo *DI = getModuleDebugInfo())
      DI->getOrCreateInterfaceType(getContext().getObjCInterfaceType(OMD->getClassInterface()),
				   OMD->getLocation());
    
    break;
  }
  case Decl::ObjCMethod: {
    ObjCMethodDecl *OMD = cast<ObjCMethodDecl>(D);
    // If this is not a prototype, emit the body.
    if (OMD->getBody())
      CodeGenFunction(*this).GenerateObjCMethod(OMD);
    break;
  }
  case Decl::ObjCCompatibleAlias:
    ObjCRuntime->RegisterAlias(cast<ObjCCompatibleAliasDecl>(D));
    break;

  case Decl::LinkageSpec:
    EmitLinkageSpec(cast<LinkageSpecDecl>(D));
    break;

  case Decl::FileScopeAsm: {
    FileScopeAsmDecl *AD = cast<FileScopeAsmDecl>(D);
    StringRef AsmString = AD->getAsmString()->getString();

    const std::string &S = getModule().getModuleInlineAsm();
    if (S.empty())
      getModule().setModuleInlineAsm(AsmString);
    else if (S.end()[-1] == '\n')
      getModule().setModuleInlineAsm(S + AsmString.str());
    else
      getModule().setModuleInlineAsm(S + '\n' + AsmString.str());
    break;
  }

  default:
    // Make sure we handled everything we should, every other kind is a
    // non-top-level decl.  FIXME: Would be nice to have an isTopLevelDeclKind
    // function. Need to recode Decl::Kind to do that easily.
    assert(isa<TypeDecl>(D) && "Unsupported decl kind");
  }
}

/// Turns the given pointer into a constant.
static llvm::Constant *GetPointerConstant(llvm::LLVMContext &Context,
                                          const void *Ptr) {
  uintptr_t PtrInt = reinterpret_cast<uintptr_t>(Ptr);
  llvm::Type *i64 = llvm::Type::getInt64Ty(Context);
  return llvm::ConstantInt::get(i64, PtrInt);
}

static void EmitGlobalDeclMetadata(CodeGenModule &CGM,
                                   llvm::NamedMDNode *&GlobalMetadata,
                                   GlobalDecl D,
                                   llvm::GlobalValue *Addr) {
  if (!GlobalMetadata)
    GlobalMetadata =
      CGM.getModule().getOrInsertNamedMetadata("clang.global.decl.ptrs");

  // TODO: should we report variant information for ctors/dtors?
  llvm::Value *Ops[] = {
    Addr,
    GetPointerConstant(CGM.getLLVMContext(), D.getDecl())
  };
  GlobalMetadata->addOperand(llvm::MDNode::get(CGM.getLLVMContext(), Ops));
}

/// Emits metadata nodes associating all the global values in the
/// current module with the Decls they came from.  This is useful for
/// projects using IR gen as a subroutine.
///
/// Since there's currently no way to associate an MDNode directly
/// with an llvm::GlobalValue, we create a global named metadata
/// with the name 'clang.global.decl.ptrs'.
void CodeGenModule::EmitDeclMetadata() {
  llvm::NamedMDNode *GlobalMetadata = 0;

  // StaticLocalDeclMap
  for (llvm::DenseMap<GlobalDecl,StringRef>::iterator
         I = MangledDeclNames.begin(), E = MangledDeclNames.end();
       I != E; ++I) {
    llvm::GlobalValue *Addr = getModule().getNamedValue(I->second);
    EmitGlobalDeclMetadata(*this, GlobalMetadata, I->first, Addr);
  }
}

/// Emits metadata nodes for all the local variables in the current
/// function.
void CodeGenFunction::EmitDeclMetadata() {
  if (LocalDeclMap.empty()) return;

  llvm::LLVMContext &Context = getLLVMContext();

  // Find the unique metadata ID for this name.
  unsigned DeclPtrKind = Context.getMDKindID("clang.decl.ptr");

  llvm::NamedMDNode *GlobalMetadata = 0;

  for (llvm::DenseMap<const Decl*, llvm::Value*>::iterator
         I = LocalDeclMap.begin(), E = LocalDeclMap.end(); I != E; ++I) {
    const Decl *D = I->first;
    llvm::Value *Addr = I->second;

    if (llvm::AllocaInst *Alloca = dyn_cast<llvm::AllocaInst>(Addr)) {
      llvm::Value *DAddr = GetPointerConstant(getLLVMContext(), D);
      Alloca->setMetadata(DeclPtrKind, llvm::MDNode::get(Context, DAddr));
    } else if (llvm::GlobalValue *GV = dyn_cast<llvm::GlobalValue>(Addr)) {
      GlobalDecl GD = GlobalDecl(cast<VarDecl>(D));
      EmitGlobalDeclMetadata(CGM, GlobalMetadata, GD, GV);
    }
  }
}

void CodeGenModule::EmitCoverageFile() {
  if (!getCodeGenOpts().CoverageFile.empty()) {
    if (llvm::NamedMDNode *CUNode = TheModule.getNamedMetadata("llvm.dbg.cu")) {
      llvm::NamedMDNode *GCov = TheModule.getOrInsertNamedMetadata("llvm.gcov");
      llvm::LLVMContext &Ctx = TheModule.getContext();
      llvm::MDString *CoverageFile =
          llvm::MDString::get(Ctx, getCodeGenOpts().CoverageFile);
      for (int i = 0, e = CUNode->getNumOperands(); i != e; ++i) {
        llvm::MDNode *CU = CUNode->getOperand(i);
        llvm::Value *node[] = { CoverageFile, CU };
        llvm::MDNode *N = llvm::MDNode::get(Ctx, node);
        GCov->addOperand(N);
      }
    }
  }
}

llvm::Constant *CodeGenModule::EmitUuidofInitializer(StringRef Uuid,
                                                     QualType GuidType) {
  // Sema has checked that all uuid strings are of the form
  // "12345678-1234-1234-1234-1234567890ab".
  assert(Uuid.size() == 36);
  const char *Uuidstr = Uuid.data();
  for (int i = 0; i < 36; ++i) {
    if (i == 8 || i == 13 || i == 18 || i == 23) assert(Uuidstr[i] == '-');
    else                                         assert(isxdigit(Uuidstr[i]));
  }
  
  llvm::APInt Field0(32, StringRef(Uuidstr     , 8), 16);
  llvm::APInt Field1(16, StringRef(Uuidstr +  9, 4), 16);
  llvm::APInt Field2(16, StringRef(Uuidstr + 14, 4), 16);
  static const int Field3ValueOffsets[] = { 19, 21, 24, 26, 28, 30, 32, 34 };

  APValue InitStruct(APValue::UninitStruct(), /*NumBases=*/0, /*NumFields=*/4);
  InitStruct.getStructField(0) = APValue(llvm::APSInt(Field0));
  InitStruct.getStructField(1) = APValue(llvm::APSInt(Field1));
  InitStruct.getStructField(2) = APValue(llvm::APSInt(Field2));
  APValue& Arr = InitStruct.getStructField(3);
  Arr = APValue(APValue::UninitArray(), 8, 8);
  for (int t = 0; t < 8; ++t)
    Arr.getArrayInitializedElt(t) = APValue(llvm::APSInt(
          llvm::APInt(8, StringRef(Uuidstr + Field3ValueOffsets[t], 2), 16)));

  return EmitConstantValue(InitStruct, GuidType);
}