xref: /llvm-project-15.0.7/clang/lib/Serialization/ASTWriterDecl.cpp (revision f5f94528)

//===--- ASTWriterDecl.cpp - Declaration Serialization --------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file implements serialization for Declarations.
//
//===----------------------------------------------------------------------===//

#include "clang/Serialization/ASTWriter.h"
#include "ASTCommon.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclContextInternals.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/DeclVisitor.h"
#include "clang/AST/Expr.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Serialization/ASTReader.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Bitcode/BitstreamWriter.h"
#include "llvm/Support/ErrorHandling.h"
using namespace clang;
using namespace serialization;

//===----------------------------------------------------------------------===//
// Declaration serialization
//===----------------------------------------------------------------------===//

namespace clang {
  class ASTDeclWriter : public DeclVisitor<ASTDeclWriter, void> {

    ASTWriter &Writer;
    ASTContext &Context;
    typedef ASTWriter::RecordData RecordData;
    RecordData &Record;

  public:
    serialization::DeclCode Code;
    unsigned AbbrevToUse;

    ASTDeclWriter(ASTWriter &Writer, ASTContext &Context, RecordData &Record)
      : Writer(Writer), Context(Context), Record(Record) {
    }

    void Visit(Decl *D);

    void VisitDecl(Decl *D);
    void VisitTranslationUnitDecl(TranslationUnitDecl *D);
    void VisitNamedDecl(NamedDecl *D);
    void VisitLabelDecl(LabelDecl *LD);
    void VisitNamespaceDecl(NamespaceDecl *D);
    void VisitUsingDirectiveDecl(UsingDirectiveDecl *D);
    void VisitNamespaceAliasDecl(NamespaceAliasDecl *D);
    void VisitTypeDecl(TypeDecl *D);
    void VisitTypedefNameDecl(TypedefNameDecl *D);
    void VisitTypedefDecl(TypedefDecl *D);
    void VisitTypeAliasDecl(TypeAliasDecl *D);
    void VisitUnresolvedUsingTypenameDecl(UnresolvedUsingTypenameDecl *D);
    void VisitTagDecl(TagDecl *D);
    void VisitEnumDecl(EnumDecl *D);
    void VisitRecordDecl(RecordDecl *D);
    void VisitCXXRecordDecl(CXXRecordDecl *D);
    void VisitClassTemplateSpecializationDecl(
                                            ClassTemplateSpecializationDecl *D);
    void VisitClassTemplatePartialSpecializationDecl(
                                     ClassTemplatePartialSpecializationDecl *D);
    void VisitClassScopeFunctionSpecializationDecl(
                                       ClassScopeFunctionSpecializationDecl *D);
    void VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D);
    void VisitValueDecl(ValueDecl *D);
    void VisitEnumConstantDecl(EnumConstantDecl *D);
    void VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D);
    void VisitDeclaratorDecl(DeclaratorDecl *D);
    void VisitFunctionDecl(FunctionDecl *D);
    void VisitCXXMethodDecl(CXXMethodDecl *D);
    void VisitCXXConstructorDecl(CXXConstructorDecl *D);
    void VisitCXXDestructorDecl(CXXDestructorDecl *D);
    void VisitCXXConversionDecl(CXXConversionDecl *D);
    void VisitFieldDecl(FieldDecl *D);
    void VisitIndirectFieldDecl(IndirectFieldDecl *D);
    void VisitVarDecl(VarDecl *D);
    void VisitImplicitParamDecl(ImplicitParamDecl *D);
    void VisitParmVarDecl(ParmVarDecl *D);
    void VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D);
    void VisitTemplateDecl(TemplateDecl *D);
    void VisitRedeclarableTemplateDecl(RedeclarableTemplateDecl *D);
    void VisitClassTemplateDecl(ClassTemplateDecl *D);
    void VisitFunctionTemplateDecl(FunctionTemplateDecl *D);
    void VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D);
    void VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D);
    void VisitUsingDecl(UsingDecl *D);
    void VisitUsingShadowDecl(UsingShadowDecl *D);
    void VisitLinkageSpecDecl(LinkageSpecDecl *D);
    void VisitFileScopeAsmDecl(FileScopeAsmDecl *D);
    void VisitImportDecl(ImportDecl *D);
    void VisitAccessSpecDecl(AccessSpecDecl *D);
    void VisitFriendDecl(FriendDecl *D);
    void VisitFriendTemplateDecl(FriendTemplateDecl *D);
    void VisitStaticAssertDecl(StaticAssertDecl *D);
    void VisitBlockDecl(BlockDecl *D);

    void VisitDeclContext(DeclContext *DC, uint64_t LexicalOffset,
                          uint64_t VisibleOffset);
    template <typename T> void VisitRedeclarable(Redeclarable<T> *D);


    // FIXME: Put in the same order is DeclNodes.td?
    void VisitObjCMethodDecl(ObjCMethodDecl *D);
    void VisitObjCContainerDecl(ObjCContainerDecl *D);
    void VisitObjCInterfaceDecl(ObjCInterfaceDecl *D);
    void VisitObjCIvarDecl(ObjCIvarDecl *D);
    void VisitObjCProtocolDecl(ObjCProtocolDecl *D);
    void VisitObjCAtDefsFieldDecl(ObjCAtDefsFieldDecl *D);
    void VisitObjCCategoryDecl(ObjCCategoryDecl *D);
    void VisitObjCImplDecl(ObjCImplDecl *D);
    void VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D);
    void VisitObjCImplementationDecl(ObjCImplementationDecl *D);
    void VisitObjCCompatibleAliasDecl(ObjCCompatibleAliasDecl *D);
    void VisitObjCPropertyDecl(ObjCPropertyDecl *D);
    void VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D);
  };
}

void ASTDeclWriter::Visit(Decl *D) {
  DeclVisitor<ASTDeclWriter>::Visit(D);

  // Source locations require array (variable-length) abbreviations.  The
  // abbreviation infrastructure requires that arrays are encoded last, so
  // we handle it here in the case of those classes derived from DeclaratorDecl
  if (DeclaratorDecl *DD = dyn_cast<DeclaratorDecl>(D)){
    Writer.AddTypeSourceInfo(DD->getTypeSourceInfo(), Record);
  }

  // Handle FunctionDecl's body here and write it after all other Stmts/Exprs
  // have been written. We want it last because we will not read it back when
  // retrieving it from the AST, we'll just lazily set the offset.
  if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
    Record.push_back(FD->doesThisDeclarationHaveABody());
    if (FD->doesThisDeclarationHaveABody())
      Writer.AddStmt(FD->getBody());
  }
}

void ASTDeclWriter::VisitDecl(Decl *D) {
  Writer.AddDeclRef(cast_or_null<Decl>(D->getDeclContext()), Record);
  Writer.AddDeclRef(cast_or_null<Decl>(D->getLexicalDeclContext()), Record);
  Record.push_back(D->isInvalidDecl());
  Record.push_back(D->hasAttrs());
  if (D->hasAttrs())
    Writer.WriteAttributes(ArrayRef<const Attr*>(D->getAttrs().begin(),
                                                 D->getAttrs().size()), Record);
  Record.push_back(D->isImplicit());
  Record.push_back(D->isUsed(false));
  Record.push_back(D->isReferenced());
  Record.push_back(D->isTopLevelDeclInObjCContainer());
  Record.push_back(D->getAccess());
  Record.push_back(D->isModulePrivate());
  Record.push_back(Writer.inferSubmoduleIDFromLocation(D->getLocation()));
}

void ASTDeclWriter::VisitTranslationUnitDecl(TranslationUnitDecl *D) {
  llvm_unreachable("Translation units aren't directly serialized");
}

void ASTDeclWriter::VisitNamedDecl(NamedDecl *D) {
  VisitDecl(D);
  Writer.AddDeclarationName(D->getDeclName(), Record);
}

void ASTDeclWriter::VisitTypeDecl(TypeDecl *D) {
  VisitNamedDecl(D);
  Writer.AddSourceLocation(D->getLocStart(), Record);
  Writer.AddTypeRef(QualType(D->getTypeForDecl(), 0), Record);
}

void ASTDeclWriter::VisitTypedefNameDecl(TypedefNameDecl *D) {
  VisitRedeclarable(D);
  VisitTypeDecl(D);
  Writer.AddTypeSourceInfo(D->getTypeSourceInfo(), Record);
}

void ASTDeclWriter::VisitTypedefDecl(TypedefDecl *D) {
  VisitTypedefNameDecl(D);
  if (!D->hasAttrs() &&
      !D->isImplicit() &&
      !D->isUsed(false) &&
      D->getFirstDeclaration() == D->getMostRecentDecl() &&
      !D->isInvalidDecl() &&
      !D->isReferenced() &&
      !D->isTopLevelDeclInObjCContainer() &&
      D->getAccess() == AS_none &&
      !D->isModulePrivate() &&
      D->getDeclName().getNameKind() == DeclarationName::Identifier)
    AbbrevToUse = Writer.getDeclTypedefAbbrev();

  Code = serialization::DECL_TYPEDEF;
}

void ASTDeclWriter::VisitTypeAliasDecl(TypeAliasDecl *D) {
  VisitTypedefNameDecl(D);
  Code = serialization::DECL_TYPEALIAS;
}

void ASTDeclWriter::VisitTagDecl(TagDecl *D) {
  VisitRedeclarable(D);
  VisitTypeDecl(D);
  Record.push_back(D->getIdentifierNamespace());
  Record.push_back((unsigned)D->getTagKind()); // FIXME: stable encoding
  Record.push_back(D->isCompleteDefinition());
  Record.push_back(D->isEmbeddedInDeclarator());
  Record.push_back(D->isFreeStanding());
  Writer.AddSourceLocation(D->getRBraceLoc(), Record);
  Record.push_back(D->hasExtInfo());
  if (D->hasExtInfo())
    Writer.AddQualifierInfo(*D->getExtInfo(), Record);
  else
    Writer.AddDeclRef(D->getTypedefNameForAnonDecl(), Record);
}

void ASTDeclWriter::VisitEnumDecl(EnumDecl *D) {
  VisitTagDecl(D);
  Writer.AddTypeSourceInfo(D->getIntegerTypeSourceInfo(), Record);
  if (!D->getIntegerTypeSourceInfo())
    Writer.AddTypeRef(D->getIntegerType(), Record);
  Writer.AddTypeRef(D->getPromotionType(), Record);
  Record.push_back(D->getNumPositiveBits());
  Record.push_back(D->getNumNegativeBits());
  Record.push_back(D->isScoped());
  Record.push_back(D->isScopedUsingClassTag());
  Record.push_back(D->isFixed());
  if (MemberSpecializationInfo *MemberInfo = D->getMemberSpecializationInfo()) {
    Writer.AddDeclRef(MemberInfo->getInstantiatedFrom(), Record);
    Record.push_back(MemberInfo->getTemplateSpecializationKind());
    Writer.AddSourceLocation(MemberInfo->getPointOfInstantiation(), Record);
  } else {
    Writer.AddDeclRef(0, Record);
  }

  if (!D->hasAttrs() &&
      !D->isImplicit() &&
      !D->isUsed(false) &&
      !D->hasExtInfo() &&
      D->getFirstDeclaration() == D->getMostRecentDecl() &&
      !D->isInvalidDecl() &&
      !D->isReferenced() &&
      !D->isTopLevelDeclInObjCContainer() &&
      D->getAccess() == AS_none &&
      !D->isModulePrivate() &&
      !CXXRecordDecl::classofKind(D->getKind()) &&
      !D->getIntegerTypeSourceInfo() &&
      D->getDeclName().getNameKind() == DeclarationName::Identifier)
    AbbrevToUse = Writer.getDeclEnumAbbrev();

  Code = serialization::DECL_ENUM;
}

void ASTDeclWriter::VisitRecordDecl(RecordDecl *D) {
  VisitTagDecl(D);
  Record.push_back(D->hasFlexibleArrayMember());
  Record.push_back(D->isAnonymousStructOrUnion());
  Record.push_back(D->hasObjectMember());
  Record.push_back(D->hasVolatileMember());

  if (!D->hasAttrs() &&
      !D->isImplicit() &&
      !D->isUsed(false) &&
      !D->hasExtInfo() &&
      D->getFirstDeclaration() == D->getMostRecentDecl() &&
      !D->isInvalidDecl() &&
      !D->isReferenced() &&
      !D->isTopLevelDeclInObjCContainer() &&
      D->getAccess() == AS_none &&
      !D->isModulePrivate() &&
      !CXXRecordDecl::classofKind(D->getKind()) &&
      D->getDeclName().getNameKind() == DeclarationName::Identifier)
    AbbrevToUse = Writer.getDeclRecordAbbrev();

  Code = serialization::DECL_RECORD;
}

void ASTDeclWriter::VisitValueDecl(ValueDecl *D) {
  VisitNamedDecl(D);
  Writer.AddTypeRef(D->getType(), Record);
}

void ASTDeclWriter::VisitEnumConstantDecl(EnumConstantDecl *D) {
  VisitValueDecl(D);
  Record.push_back(D->getInitExpr()? 1 : 0);
  if (D->getInitExpr())
    Writer.AddStmt(D->getInitExpr());
  Writer.AddAPSInt(D->getInitVal(), Record);

  Code = serialization::DECL_ENUM_CONSTANT;
}

void ASTDeclWriter::VisitDeclaratorDecl(DeclaratorDecl *D) {
  VisitValueDecl(D);
  Writer.AddSourceLocation(D->getInnerLocStart(), Record);
  Record.push_back(D->hasExtInfo());
  if (D->hasExtInfo())
    Writer.AddQualifierInfo(*D->getExtInfo(), Record);
}

void ASTDeclWriter::VisitFunctionDecl(FunctionDecl *D) {
  VisitRedeclarable(D);
  VisitDeclaratorDecl(D);

  Writer.AddDeclarationNameLoc(D->DNLoc, D->getDeclName(), Record);
  Record.push_back(D->getIdentifierNamespace());

  // FunctionDecl's body is handled last at ASTWriterDecl::Visit,
  // after everything else is written.

  Record.push_back(D->getStorageClass()); // FIXME: stable encoding
  Record.push_back(D->getStorageClassAsWritten());
  Record.push_back(D->IsInline);
  Record.push_back(D->isInlineSpecified());
  Record.push_back(D->isVirtualAsWritten());
  Record.push_back(D->isPure());
  Record.push_back(D->hasInheritedPrototype());
  Record.push_back(D->hasWrittenPrototype());
  Record.push_back(D->isDeletedAsWritten());
  Record.push_back(D->isTrivial());
  Record.push_back(D->isDefaulted());
  Record.push_back(D->isExplicitlyDefaulted());
  Record.push_back(D->hasImplicitReturnZero());
  Record.push_back(D->isConstexpr());
  Record.push_back(D->HasSkippedBody);
  Writer.AddSourceLocation(D->getLocEnd(), Record);

  Record.push_back(D->getTemplatedKind());
  switch (D->getTemplatedKind()) {
  case FunctionDecl::TK_NonTemplate:
    break;
  case FunctionDecl::TK_FunctionTemplate:
    Writer.AddDeclRef(D->getDescribedFunctionTemplate(), Record);
    break;
  case FunctionDecl::TK_MemberSpecialization: {
    MemberSpecializationInfo *MemberInfo = D->getMemberSpecializationInfo();
    Writer.AddDeclRef(MemberInfo->getInstantiatedFrom(), Record);
    Record.push_back(MemberInfo->getTemplateSpecializationKind());
    Writer.AddSourceLocation(MemberInfo->getPointOfInstantiation(), Record);
    break;
  }
  case FunctionDecl::TK_FunctionTemplateSpecialization: {
    FunctionTemplateSpecializationInfo *
      FTSInfo = D->getTemplateSpecializationInfo();
    Writer.AddDeclRef(FTSInfo->getTemplate(), Record);
    Record.push_back(FTSInfo->getTemplateSpecializationKind());

    // Template arguments.
    Writer.AddTemplateArgumentList(FTSInfo->TemplateArguments, Record);

    // Template args as written.
    Record.push_back(FTSInfo->TemplateArgumentsAsWritten != 0);
    if (FTSInfo->TemplateArgumentsAsWritten) {
      Record.push_back(FTSInfo->TemplateArgumentsAsWritten->NumTemplateArgs);
      for (int i=0, e = FTSInfo->TemplateArgumentsAsWritten->NumTemplateArgs;
             i!=e; ++i)
        Writer.AddTemplateArgumentLoc((*FTSInfo->TemplateArgumentsAsWritten)[i],
                                      Record);
      Writer.AddSourceLocation(FTSInfo->TemplateArgumentsAsWritten->LAngleLoc,
                               Record);
      Writer.AddSourceLocation(FTSInfo->TemplateArgumentsAsWritten->RAngleLoc,
                               Record);
    }

    Writer.AddSourceLocation(FTSInfo->getPointOfInstantiation(), Record);

    if (D->isCanonicalDecl()) {
      // Write the template that contains the specializations set. We will
      // add a FunctionTemplateSpecializationInfo to it when reading.
      Writer.AddDeclRef(FTSInfo->getTemplate()->getCanonicalDecl(), Record);
    }
    break;
  }
  case FunctionDecl::TK_DependentFunctionTemplateSpecialization: {
    DependentFunctionTemplateSpecializationInfo *
      DFTSInfo = D->getDependentSpecializationInfo();

    // Templates.
    Record.push_back(DFTSInfo->getNumTemplates());
    for (int i=0, e = DFTSInfo->getNumTemplates(); i != e; ++i)
      Writer.AddDeclRef(DFTSInfo->getTemplate(i), Record);

    // Templates args.
    Record.push_back(DFTSInfo->getNumTemplateArgs());
    for (int i=0, e = DFTSInfo->getNumTemplateArgs(); i != e; ++i)
      Writer.AddTemplateArgumentLoc(DFTSInfo->getTemplateArg(i), Record);
    Writer.AddSourceLocation(DFTSInfo->getLAngleLoc(), Record);
    Writer.AddSourceLocation(DFTSInfo->getRAngleLoc(), Record);
    break;
  }
  }

  Record.push_back(D->param_size());
  for (FunctionDecl::param_iterator P = D->param_begin(), PEnd = D->param_end();
       P != PEnd; ++P)
    Writer.AddDeclRef(*P, Record);
  Code = serialization::DECL_FUNCTION;
}

void ASTDeclWriter::VisitObjCMethodDecl(ObjCMethodDecl *D) {
  VisitNamedDecl(D);
  // FIXME: convert to LazyStmtPtr?
  // Unlike C/C++, method bodies will never be in header files.
  bool HasBodyStuff = D->getBody() != 0     ||
                      D->getSelfDecl() != 0 || D->getCmdDecl() != 0;
  Record.push_back(HasBodyStuff);
  if (HasBodyStuff) {
    Writer.AddStmt(D->getBody());
    Writer.AddDeclRef(D->getSelfDecl(), Record);
    Writer.AddDeclRef(D->getCmdDecl(), Record);
  }
  Record.push_back(D->isInstanceMethod());
  Record.push_back(D->isVariadic());
  Record.push_back(D->isPropertyAccessor());
  Record.push_back(D->isDefined());
  Record.push_back(D->IsOverriding);
  Record.push_back(D->HasSkippedBody);

  Record.push_back(D->IsRedeclaration);
  Record.push_back(D->HasRedeclaration);
  if (D->HasRedeclaration) {
    assert(Context.getObjCMethodRedeclaration(D));
    Writer.AddDeclRef(Context.getObjCMethodRedeclaration(D), Record);
  }

  // FIXME: stable encoding for @required/@optional
  Record.push_back(D->getImplementationControl());
  // FIXME: stable encoding for in/out/inout/bycopy/byref/oneway
  Record.push_back(D->getObjCDeclQualifier());
  Record.push_back(D->hasRelatedResultType());
  Writer.AddTypeRef(D->getResultType(), Record);
  Writer.AddTypeSourceInfo(D->getResultTypeSourceInfo(), Record);
  Writer.AddSourceLocation(D->getLocEnd(), Record);
  Record.push_back(D->param_size());
  for (ObjCMethodDecl::param_iterator P = D->param_begin(),
                                   PEnd = D->param_end(); P != PEnd; ++P)
    Writer.AddDeclRef(*P, Record);

  Record.push_back(D->SelLocsKind);
  unsigned NumStoredSelLocs = D->getNumStoredSelLocs();
  SourceLocation *SelLocs = D->getStoredSelLocs();
  Record.push_back(NumStoredSelLocs);
  for (unsigned i = 0; i != NumStoredSelLocs; ++i)
    Writer.AddSourceLocation(SelLocs[i], Record);

  Code = serialization::DECL_OBJC_METHOD;
}

void ASTDeclWriter::VisitObjCContainerDecl(ObjCContainerDecl *D) {
  VisitNamedDecl(D);
  Writer.AddSourceLocation(D->getAtStartLoc(), Record);
  Writer.AddSourceRange(D->getAtEndRange(), Record);
  // Abstract class (no need to define a stable serialization::DECL code).
}

void ASTDeclWriter::VisitObjCInterfaceDecl(ObjCInterfaceDecl *D) {
  VisitRedeclarable(D);
  VisitObjCContainerDecl(D);
  Writer.AddTypeRef(QualType(D->getTypeForDecl(), 0), Record);

  Record.push_back(D->isThisDeclarationADefinition());
  if (D->isThisDeclarationADefinition()) {
    // Write the DefinitionData
    ObjCInterfaceDecl::DefinitionData &Data = D->data();

    Writer.AddDeclRef(D->getSuperClass(), Record);
    Writer.AddSourceLocation(D->getSuperClassLoc(), Record);
    Writer.AddSourceLocation(D->getEndOfDefinitionLoc(), Record);

    // Write out the protocols that are directly referenced by the @interface.
    Record.push_back(Data.ReferencedProtocols.size());
    for (ObjCInterfaceDecl::protocol_iterator P = D->protocol_begin(),
                                           PEnd = D->protocol_end();
         P != PEnd; ++P)
      Writer.AddDeclRef(*P, Record);
    for (ObjCInterfaceDecl::protocol_loc_iterator PL = D->protocol_loc_begin(),
         PLEnd = D->protocol_loc_end();
         PL != PLEnd; ++PL)
      Writer.AddSourceLocation(*PL, Record);

    // Write out the protocols that are transitively referenced.
    Record.push_back(Data.AllReferencedProtocols.size());
    for (ObjCList<ObjCProtocolDecl>::iterator
              P = Data.AllReferencedProtocols.begin(),
           PEnd = Data.AllReferencedProtocols.end();
         P != PEnd; ++P)
      Writer.AddDeclRef(*P, Record);


    if (ObjCCategoryDecl *Cat = D->getCategoryListRaw()) {
      // Ensure that we write out the set of categories for this class.
      Writer.ObjCClassesWithCategories.insert(D);

      // Make sure that the categories get serialized.
      for (; Cat; Cat = Cat->getNextClassCategoryRaw())
        (void)Writer.GetDeclRef(Cat);
    }
  }

  Code = serialization::DECL_OBJC_INTERFACE;
}

void ASTDeclWriter::VisitObjCIvarDecl(ObjCIvarDecl *D) {
  VisitFieldDecl(D);
  // FIXME: stable encoding for @public/@private/@protected/@package
  Record.push_back(D->getAccessControl());
  Record.push_back(D->getSynthesize());

  if (!D->hasAttrs() &&
      !D->isImplicit() &&
      !D->isUsed(false) &&
      !D->isInvalidDecl() &&
      !D->isReferenced() &&
      !D->isModulePrivate() &&
      !D->getBitWidth() &&
      !D->hasExtInfo() &&
      D->getDeclName())
    AbbrevToUse = Writer.getDeclObjCIvarAbbrev();

  Code = serialization::DECL_OBJC_IVAR;
}

void ASTDeclWriter::VisitObjCProtocolDecl(ObjCProtocolDecl *D) {
  VisitRedeclarable(D);
  VisitObjCContainerDecl(D);

  Record.push_back(D->isThisDeclarationADefinition());
  if (D->isThisDeclarationADefinition()) {
    Record.push_back(D->protocol_size());
    for (ObjCProtocolDecl::protocol_iterator
         I = D->protocol_begin(), IEnd = D->protocol_end(); I != IEnd; ++I)
      Writer.AddDeclRef(*I, Record);
    for (ObjCProtocolDecl::protocol_loc_iterator PL = D->protocol_loc_begin(),
           PLEnd = D->protocol_loc_end();
         PL != PLEnd; ++PL)
      Writer.AddSourceLocation(*PL, Record);
  }

  Code = serialization::DECL_OBJC_PROTOCOL;
}

void ASTDeclWriter::VisitObjCAtDefsFieldDecl(ObjCAtDefsFieldDecl *D) {
  VisitFieldDecl(D);
  Code = serialization::DECL_OBJC_AT_DEFS_FIELD;
}

void ASTDeclWriter::VisitObjCCategoryDecl(ObjCCategoryDecl *D) {
  VisitObjCContainerDecl(D);
  Writer.AddSourceLocation(D->getCategoryNameLoc(), Record);
  Writer.AddSourceLocation(D->getIvarLBraceLoc(), Record);
  Writer.AddSourceLocation(D->getIvarRBraceLoc(), Record);
  Writer.AddDeclRef(D->getClassInterface(), Record);
  Record.push_back(D->protocol_size());
  for (ObjCCategoryDecl::protocol_iterator
       I = D->protocol_begin(), IEnd = D->protocol_end(); I != IEnd; ++I)
    Writer.AddDeclRef(*I, Record);
  for (ObjCCategoryDecl::protocol_loc_iterator
         PL = D->protocol_loc_begin(), PLEnd = D->protocol_loc_end();
       PL != PLEnd; ++PL)
    Writer.AddSourceLocation(*PL, Record);
  Code = serialization::DECL_OBJC_CATEGORY;
}

void ASTDeclWriter::VisitObjCCompatibleAliasDecl(ObjCCompatibleAliasDecl *D) {
  VisitNamedDecl(D);
  Writer.AddDeclRef(D->getClassInterface(), Record);
  Code = serialization::DECL_OBJC_COMPATIBLE_ALIAS;
}

void ASTDeclWriter::VisitObjCPropertyDecl(ObjCPropertyDecl *D) {
  VisitNamedDecl(D);
  Writer.AddSourceLocation(D->getAtLoc(), Record);
  Writer.AddSourceLocation(D->getLParenLoc(), Record);
  Writer.AddTypeSourceInfo(D->getTypeSourceInfo(), Record);
  // FIXME: stable encoding
  Record.push_back((unsigned)D->getPropertyAttributes());
  Record.push_back((unsigned)D->getPropertyAttributesAsWritten());
  // FIXME: stable encoding
  Record.push_back((unsigned)D->getPropertyImplementation());
  Writer.AddDeclarationName(D->getGetterName(), Record);
  Writer.AddDeclarationName(D->getSetterName(), Record);
  Writer.AddDeclRef(D->getGetterMethodDecl(), Record);
  Writer.AddDeclRef(D->getSetterMethodDecl(), Record);
  Writer.AddDeclRef(D->getPropertyIvarDecl(), Record);
  Code = serialization::DECL_OBJC_PROPERTY;
}

void ASTDeclWriter::VisitObjCImplDecl(ObjCImplDecl *D) {
  VisitObjCContainerDecl(D);
  Writer.AddDeclRef(D->getClassInterface(), Record);
  // Abstract class (no need to define a stable serialization::DECL code).
}

void ASTDeclWriter::VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D) {
  VisitObjCImplDecl(D);
  Writer.AddIdentifierRef(D->getIdentifier(), Record);
  Writer.AddSourceLocation(D->getCategoryNameLoc(), Record);
  Code = serialization::DECL_OBJC_CATEGORY_IMPL;
}

void ASTDeclWriter::VisitObjCImplementationDecl(ObjCImplementationDecl *D) {
  VisitObjCImplDecl(D);
  Writer.AddDeclRef(D->getSuperClass(), Record);
  Writer.AddSourceLocation(D->getIvarLBraceLoc(), Record);
  Writer.AddSourceLocation(D->getIvarRBraceLoc(), Record);
  Record.push_back(D->hasNonZeroConstructors());
  Record.push_back(D->hasDestructors());
  Writer.AddCXXCtorInitializers(D->IvarInitializers, D->NumIvarInitializers,
                                Record);
  Code = serialization::DECL_OBJC_IMPLEMENTATION;
}

void ASTDeclWriter::VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D) {
  VisitDecl(D);
  Writer.AddSourceLocation(D->getLocStart(), Record);
  Writer.AddDeclRef(D->getPropertyDecl(), Record);
  Writer.AddDeclRef(D->getPropertyIvarDecl(), Record);
  Writer.AddSourceLocation(D->getPropertyIvarDeclLoc(), Record);
  Writer.AddStmt(D->getGetterCXXConstructor());
  Writer.AddStmt(D->getSetterCXXAssignment());
  Code = serialization::DECL_OBJC_PROPERTY_IMPL;
}

void ASTDeclWriter::VisitFieldDecl(FieldDecl *D) {
  VisitDeclaratorDecl(D);
  Record.push_back(D->isMutable());
  if (D->InitializerOrBitWidth.getInt() != ICIS_NoInit ||
      D->InitializerOrBitWidth.getPointer()) {
    Record.push_back(D->InitializerOrBitWidth.getInt() + 1);
    Writer.AddStmt(D->InitializerOrBitWidth.getPointer());
  } else {
    Record.push_back(0);
  }
  if (!D->getDeclName())
    Writer.AddDeclRef(Context.getInstantiatedFromUnnamedFieldDecl(D), Record);

  if (!D->hasAttrs() &&
      !D->isImplicit() &&
      !D->isUsed(false) &&
      !D->isInvalidDecl() &&
      !D->isReferenced() &&
      !D->isTopLevelDeclInObjCContainer() &&
      !D->isModulePrivate() &&
      !D->getBitWidth() &&
      !D->hasInClassInitializer() &&
      !D->hasExtInfo() &&
      !ObjCIvarDecl::classofKind(D->getKind()) &&
      !ObjCAtDefsFieldDecl::classofKind(D->getKind()) &&
      D->getDeclName())
    AbbrevToUse = Writer.getDeclFieldAbbrev();

  Code = serialization::DECL_FIELD;
}

void ASTDeclWriter::VisitIndirectFieldDecl(IndirectFieldDecl *D) {
  VisitValueDecl(D);
  Record.push_back(D->getChainingSize());

  for (IndirectFieldDecl::chain_iterator
       P = D->chain_begin(),
       PEnd = D->chain_end(); P != PEnd; ++P)
    Writer.AddDeclRef(*P, Record);
  Code = serialization::DECL_INDIRECTFIELD;
}

void ASTDeclWriter::VisitVarDecl(VarDecl *D) {
  VisitRedeclarable(D);
  VisitDeclaratorDecl(D);
  Record.push_back(D->getStorageClass()); // FIXME: stable encoding
  Record.push_back(D->getStorageClassAsWritten());
  Record.push_back(D->isThreadSpecified());
  Record.push_back(D->getInitStyle());
  Record.push_back(D->isExceptionVariable());
  Record.push_back(D->isNRVOVariable());
  Record.push_back(D->isCXXForRangeDecl());
  Record.push_back(D->isARCPseudoStrong());
  Record.push_back(D->isConstexpr());

  if (D->getInit()) {
    Record.push_back(!D->isInitKnownICE() ? 1 : (D->isInitICE() ? 3 : 2));
    Writer.AddStmt(D->getInit());
  } else {
    Record.push_back(0);
  }

  MemberSpecializationInfo *SpecInfo
    = D->isStaticDataMember() ? D->getMemberSpecializationInfo() : 0;
  Record.push_back(SpecInfo != 0);
  if (SpecInfo) {
    Writer.AddDeclRef(SpecInfo->getInstantiatedFrom(), Record);
    Record.push_back(SpecInfo->getTemplateSpecializationKind());
    Writer.AddSourceLocation(SpecInfo->getPointOfInstantiation(), Record);
  }

  if (!D->hasAttrs() &&
      !D->isImplicit() &&
      !D->isUsed(false) &&
      !D->isInvalidDecl() &&
      !D->isReferenced() &&
      !D->isTopLevelDeclInObjCContainer() &&
      D->getAccess() == AS_none &&
      !D->isModulePrivate() &&
      D->getDeclName().getNameKind() == DeclarationName::Identifier &&
      !D->hasExtInfo() &&
      D->getFirstDeclaration() == D->getMostRecentDecl() &&
      D->getInitStyle() == VarDecl::CInit &&
      D->getInit() == 0 &&
      !isa<ParmVarDecl>(D) &&
      !D->isConstexpr() &&
      !SpecInfo)
    AbbrevToUse = Writer.getDeclVarAbbrev();

  Code = serialization::DECL_VAR;
}

void ASTDeclWriter::VisitImplicitParamDecl(ImplicitParamDecl *D) {
  VisitVarDecl(D);
  Code = serialization::DECL_IMPLICIT_PARAM;
}

void ASTDeclWriter::VisitParmVarDecl(ParmVarDecl *D) {
  VisitVarDecl(D);
  Record.push_back(D->isObjCMethodParameter());
  Record.push_back(D->getFunctionScopeDepth());
  Record.push_back(D->getFunctionScopeIndex());
  Record.push_back(D->getObjCDeclQualifier()); // FIXME: stable encoding
  Record.push_back(D->isKNRPromoted());
  Record.push_back(D->hasInheritedDefaultArg());
  Record.push_back(D->hasUninstantiatedDefaultArg());
  if (D->hasUninstantiatedDefaultArg())
    Writer.AddStmt(D->getUninstantiatedDefaultArg());
  Code = serialization::DECL_PARM_VAR;

  assert(!D->isARCPseudoStrong()); // can be true of ImplicitParamDecl

  // If the assumptions about the DECL_PARM_VAR abbrev are true, use it.  Here
  // we dynamically check for the properties that we optimize for, but don't
  // know are true of all PARM_VAR_DECLs.
  if (!D->hasAttrs() &&
      !D->hasExtInfo() &&
      !D->isImplicit() &&
      !D->isUsed(false) &&
      !D->isInvalidDecl() &&
      !D->isReferenced() &&
      D->getAccess() == AS_none &&
      !D->isModulePrivate() &&
      D->getStorageClass() == 0 &&
      D->getInitStyle() == VarDecl::CInit && // Can params have anything else?
      D->getFunctionScopeDepth() == 0 &&
      D->getObjCDeclQualifier() == 0 &&
      !D->isKNRPromoted() &&
      !D->hasInheritedDefaultArg() &&
      D->getInit() == 0 &&
      !D->hasUninstantiatedDefaultArg())  // No default expr.
    AbbrevToUse = Writer.getDeclParmVarAbbrev();

  // Check things we know are true of *every* PARM_VAR_DECL, which is more than
  // just us assuming it.
  assert(!D->isThreadSpecified() && "PARM_VAR_DECL can't be __thread");
  assert(D->getAccess() == AS_none && "PARM_VAR_DECL can't be public/private");
  assert(!D->isExceptionVariable() && "PARM_VAR_DECL can't be exception var");
  assert(D->getPreviousDecl() == 0 && "PARM_VAR_DECL can't be redecl");
  assert(!D->isStaticDataMember() &&
         "PARM_VAR_DECL can't be static data member");
}

void ASTDeclWriter::VisitFileScopeAsmDecl(FileScopeAsmDecl *D) {
  VisitDecl(D);
  Writer.AddStmt(D->getAsmString());
  Writer.AddSourceLocation(D->getRParenLoc(), Record);
  Code = serialization::DECL_FILE_SCOPE_ASM;
}

void ASTDeclWriter::VisitBlockDecl(BlockDecl *D) {
  VisitDecl(D);
  Writer.AddStmt(D->getBody());
  Writer.AddTypeSourceInfo(D->getSignatureAsWritten(), Record);
  Record.push_back(D->param_size());
  for (FunctionDecl::param_iterator P = D->param_begin(), PEnd = D->param_end();
       P != PEnd; ++P)
    Writer.AddDeclRef(*P, Record);
  Record.push_back(D->isVariadic());
  Record.push_back(D->blockMissingReturnType());
  Record.push_back(D->isConversionFromLambda());
  Record.push_back(D->capturesCXXThis());
  Record.push_back(D->getNumCaptures());
  for (BlockDecl::capture_iterator
         i = D->capture_begin(), e = D->capture_end(); i != e; ++i) {
    const BlockDecl::Capture &capture = *i;
    Writer.AddDeclRef(capture.getVariable(), Record);

    unsigned flags = 0;
    if (capture.isByRef()) flags |= 1;
    if (capture.isNested()) flags |= 2;
    if (capture.hasCopyExpr()) flags |= 4;
    Record.push_back(flags);

    if (capture.hasCopyExpr()) Writer.AddStmt(capture.getCopyExpr());
  }

  Code = serialization::DECL_BLOCK;
}

void ASTDeclWriter::VisitLinkageSpecDecl(LinkageSpecDecl *D) {
  VisitDecl(D);
  Record.push_back(D->getLanguage());
  Writer.AddSourceLocation(D->getExternLoc(), Record);
  Writer.AddSourceLocation(D->getRBraceLoc(), Record);
  Code = serialization::DECL_LINKAGE_SPEC;
}

void ASTDeclWriter::VisitLabelDecl(LabelDecl *D) {
  VisitNamedDecl(D);
  Writer.AddSourceLocation(D->getLocStart(), Record);
  Code = serialization::DECL_LABEL;
}


void ASTDeclWriter::VisitNamespaceDecl(NamespaceDecl *D) {
  VisitRedeclarable(D);
  VisitNamedDecl(D);
  Record.push_back(D->isInline());
  Writer.AddSourceLocation(D->getLocStart(), Record);
  Writer.AddSourceLocation(D->getRBraceLoc(), Record);

  if (D->isOriginalNamespace())
    Writer.AddDeclRef(D->getAnonymousNamespace(), Record);
  Code = serialization::DECL_NAMESPACE;

  if (Writer.hasChain() && !D->isOriginalNamespace() &&
      D->getOriginalNamespace()->isFromASTFile()) {
    NamespaceDecl *NS = D->getOriginalNamespace();
    Writer.AddUpdatedDeclContext(NS);

    // Make sure all visible decls are written. They will be recorded later.
    if (StoredDeclsMap *Map = NS->buildLookup()) {
      for (StoredDeclsMap::iterator D = Map->begin(), DEnd = Map->end();
           D != DEnd; ++D) {
        DeclContext::lookup_result R = D->second.getLookupResult();
        for (DeclContext::lookup_iterator I = R.begin(), E = R.end(); I != E;
             ++I)
          Writer.GetDeclRef(*I);
      }
    }
  }

  if (Writer.hasChain() && D->isAnonymousNamespace() &&
      D == D->getMostRecentDecl()) {
    // This is a most recent reopening of the anonymous namespace. If its parent
    // is in a previous PCH (or is the TU), mark that parent for update, because
    // the original namespace always points to the latest re-opening of its
    // anonymous namespace.
    Decl *Parent = cast<Decl>(
        D->getParent()->getRedeclContext()->getPrimaryContext());
    if (Parent->isFromASTFile() || isa<TranslationUnitDecl>(Parent)) {
      ASTWriter::UpdateRecord &Record = Writer.DeclUpdates[Parent];
      Record.push_back(UPD_CXX_ADDED_ANONYMOUS_NAMESPACE);
      Writer.AddDeclRef(D, Record);
    }
  }
}

void ASTDeclWriter::VisitNamespaceAliasDecl(NamespaceAliasDecl *D) {
  VisitNamedDecl(D);
  Writer.AddSourceLocation(D->getNamespaceLoc(), Record);
  Writer.AddSourceLocation(D->getTargetNameLoc(), Record);
  Writer.AddNestedNameSpecifierLoc(D->getQualifierLoc(), Record);
  Writer.AddDeclRef(D->getNamespace(), Record);
  Code = serialization::DECL_NAMESPACE_ALIAS;
}

void ASTDeclWriter::VisitUsingDecl(UsingDecl *D) {
  VisitNamedDecl(D);
  Writer.AddSourceLocation(D->getUsingLocation(), Record);
  Writer.AddNestedNameSpecifierLoc(D->getQualifierLoc(), Record);
  Writer.AddDeclarationNameLoc(D->DNLoc, D->getDeclName(), Record);
  Writer.AddDeclRef(D->FirstUsingShadow.getPointer(), Record);
  Record.push_back(D->isTypeName());
  Writer.AddDeclRef(Context.getInstantiatedFromUsingDecl(D), Record);
  Code = serialization::DECL_USING;
}

void ASTDeclWriter::VisitUsingShadowDecl(UsingShadowDecl *D) {
  VisitNamedDecl(D);
  Writer.AddDeclRef(D->getTargetDecl(), Record);
  Writer.AddDeclRef(D->UsingOrNextShadow, Record);
  Writer.AddDeclRef(Context.getInstantiatedFromUsingShadowDecl(D), Record);
  Code = serialization::DECL_USING_SHADOW;
}

void ASTDeclWriter::VisitUsingDirectiveDecl(UsingDirectiveDecl *D) {
  VisitNamedDecl(D);
  Writer.AddSourceLocation(D->getUsingLoc(), Record);
  Writer.AddSourceLocation(D->getNamespaceKeyLocation(), Record);
  Writer.AddNestedNameSpecifierLoc(D->getQualifierLoc(), Record);
  Writer.AddDeclRef(D->getNominatedNamespace(), Record);
  Writer.AddDeclRef(dyn_cast<Decl>(D->getCommonAncestor()), Record);
  Code = serialization::DECL_USING_DIRECTIVE;
}

void ASTDeclWriter::VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D) {
  VisitValueDecl(D);
  Writer.AddSourceLocation(D->getUsingLoc(), Record);
  Writer.AddNestedNameSpecifierLoc(D->getQualifierLoc(), Record);
  Writer.AddDeclarationNameLoc(D->DNLoc, D->getDeclName(), Record);
  Code = serialization::DECL_UNRESOLVED_USING_VALUE;
}

void ASTDeclWriter::VisitUnresolvedUsingTypenameDecl(
                                               UnresolvedUsingTypenameDecl *D) {
  VisitTypeDecl(D);
  Writer.AddSourceLocation(D->getTypenameLoc(), Record);
  Writer.AddNestedNameSpecifierLoc(D->getQualifierLoc(), Record);
  Code = serialization::DECL_UNRESOLVED_USING_TYPENAME;
}

void ASTDeclWriter::VisitCXXRecordDecl(CXXRecordDecl *D) {
  VisitRecordDecl(D);
  Record.push_back(D->isThisDeclarationADefinition());
  if (D->isThisDeclarationADefinition())
    Writer.AddCXXDefinitionData(D, Record);

  enum {
    CXXRecNotTemplate = 0, CXXRecTemplate, CXXRecMemberSpecialization
  };
  if (ClassTemplateDecl *TemplD = D->getDescribedClassTemplate()) {
    Record.push_back(CXXRecTemplate);
    Writer.AddDeclRef(TemplD, Record);
  } else if (MemberSpecializationInfo *MSInfo
               = D->getMemberSpecializationInfo()) {
    Record.push_back(CXXRecMemberSpecialization);
    Writer.AddDeclRef(MSInfo->getInstantiatedFrom(), Record);
    Record.push_back(MSInfo->getTemplateSpecializationKind());
    Writer.AddSourceLocation(MSInfo->getPointOfInstantiation(), Record);
  } else {
    Record.push_back(CXXRecNotTemplate);
  }

  // Store (what we currently believe to be) the key function to avoid
  // deserializing every method so we can compute it.
  if (D->IsCompleteDefinition)
    Writer.AddDeclRef(Context.getCurrentKeyFunction(D), Record);

  Code = serialization::DECL_CXX_RECORD;
}

void ASTDeclWriter::VisitCXXMethodDecl(CXXMethodDecl *D) {
  VisitFunctionDecl(D);
  if (D->isCanonicalDecl()) {
    Record.push_back(D->size_overridden_methods());
    for (CXXMethodDecl::method_iterator
           I = D->begin_overridden_methods(), E = D->end_overridden_methods();
           I != E; ++I)
      Writer.AddDeclRef(*I, Record);
  } else {
    // We only need to record overridden methods once for the canonical decl.
    Record.push_back(0);
  }
  Code = serialization::DECL_CXX_METHOD;
}

void ASTDeclWriter::VisitCXXConstructorDecl(CXXConstructorDecl *D) {
  VisitCXXMethodDecl(D);

  Record.push_back(D->IsExplicitSpecified);
  Record.push_back(D->ImplicitlyDefined);
  Writer.AddCXXCtorInitializers(D->CtorInitializers, D->NumCtorInitializers,
                                Record);

  Code = serialization::DECL_CXX_CONSTRUCTOR;
}

void ASTDeclWriter::VisitCXXDestructorDecl(CXXDestructorDecl *D) {
  VisitCXXMethodDecl(D);

  Record.push_back(D->ImplicitlyDefined);
  Writer.AddDeclRef(D->OperatorDelete, Record);

  Code = serialization::DECL_CXX_DESTRUCTOR;
}

void ASTDeclWriter::VisitCXXConversionDecl(CXXConversionDecl *D) {
  VisitCXXMethodDecl(D);
  Record.push_back(D->IsExplicitSpecified);
  Code = serialization::DECL_CXX_CONVERSION;
}

void ASTDeclWriter::VisitImportDecl(ImportDecl *D) {
  VisitDecl(D);
  Record.push_back(Writer.getSubmoduleID(D->getImportedModule()));
  ArrayRef<SourceLocation> IdentifierLocs = D->getIdentifierLocs();
  Record.push_back(!IdentifierLocs.empty());
  if (IdentifierLocs.empty()) {
    Writer.AddSourceLocation(D->getLocEnd(), Record);
    Record.push_back(1);
  } else {
    for (unsigned I = 0, N = IdentifierLocs.size(); I != N; ++I)
      Writer.AddSourceLocation(IdentifierLocs[I], Record);
    Record.push_back(IdentifierLocs.size());
  }
  // Note: the number of source locations must always be the last element in
  // the record.
  Code = serialization::DECL_IMPORT;
}

void ASTDeclWriter::VisitAccessSpecDecl(AccessSpecDecl *D) {
  VisitDecl(D);
  Writer.AddSourceLocation(D->getColonLoc(), Record);
  Code = serialization::DECL_ACCESS_SPEC;
}

void ASTDeclWriter::VisitFriendDecl(FriendDecl *D) {
  // Record the number of friend type template parameter lists here
  // so as to simplify memory allocation during deserialization.
  Record.push_back(D->NumTPLists);
  VisitDecl(D);
  bool hasFriendDecl = D->Friend.is<NamedDecl*>();
  Record.push_back(hasFriendDecl);
  if (hasFriendDecl)
    Writer.AddDeclRef(D->getFriendDecl(), Record);
  else
    Writer.AddTypeSourceInfo(D->getFriendType(), Record);
  for (unsigned i = 0; i < D->NumTPLists; ++i)
    Writer.AddTemplateParameterList(D->getFriendTypeTemplateParameterList(i),
                                    Record);
  Writer.AddDeclRef(D->getNextFriend(), Record);
  Record.push_back(D->UnsupportedFriend);
  Writer.AddSourceLocation(D->FriendLoc, Record);
  Code = serialization::DECL_FRIEND;
}

void ASTDeclWriter::VisitFriendTemplateDecl(FriendTemplateDecl *D) {
  VisitDecl(D);
  Record.push_back(D->getNumTemplateParameters());
  for (unsigned i = 0, e = D->getNumTemplateParameters(); i != e; ++i)
    Writer.AddTemplateParameterList(D->getTemplateParameterList(i), Record);
  Record.push_back(D->getFriendDecl() != 0);
  if (D->getFriendDecl())
    Writer.AddDeclRef(D->getFriendDecl(), Record);
  else
    Writer.AddTypeSourceInfo(D->getFriendType(), Record);
  Writer.AddSourceLocation(D->getFriendLoc(), Record);
  Code = serialization::DECL_FRIEND_TEMPLATE;
}

void ASTDeclWriter::VisitTemplateDecl(TemplateDecl *D) {
  VisitNamedDecl(D);

  Writer.AddDeclRef(D->getTemplatedDecl(), Record);
  Writer.AddTemplateParameterList(D->getTemplateParameters(), Record);
}

void ASTDeclWriter::VisitRedeclarableTemplateDecl(RedeclarableTemplateDecl *D) {
  VisitRedeclarable(D);

  // Emit data to initialize CommonOrPrev before VisitTemplateDecl so that
  // getCommonPtr() can be used while this is still initializing.
  if (D->isFirstDeclaration()) {
    // This declaration owns the 'common' pointer, so serialize that data now.
    Writer.AddDeclRef(D->getInstantiatedFromMemberTemplate(), Record);
    if (D->getInstantiatedFromMemberTemplate())
      Record.push_back(D->isMemberSpecialization());
  }

  VisitTemplateDecl(D);
  Record.push_back(D->getIdentifierNamespace());
}

void ASTDeclWriter::VisitClassTemplateDecl(ClassTemplateDecl *D) {
  VisitRedeclarableTemplateDecl(D);

  if (D->isFirstDeclaration()) {
    typedef llvm::FoldingSetVector<ClassTemplateSpecializationDecl> CTSDSetTy;
    CTSDSetTy &CTSDSet = D->getSpecializations();
    Record.push_back(CTSDSet.size());
    for (CTSDSetTy::iterator I=CTSDSet.begin(), E = CTSDSet.end(); I!=E; ++I) {
      assert(I->isCanonicalDecl() && "Expected only canonical decls in set");
      Writer.AddDeclRef(&*I, Record);
    }

    typedef llvm::FoldingSetVector<ClassTemplatePartialSpecializationDecl>
      CTPSDSetTy;
    CTPSDSetTy &CTPSDSet = D->getPartialSpecializations();
    Record.push_back(CTPSDSet.size());
    for (CTPSDSetTy::iterator I=CTPSDSet.begin(), E=CTPSDSet.end(); I!=E; ++I) {
      assert(I->isCanonicalDecl() && "Expected only canonical decls in set");
      Writer.AddDeclRef(&*I, Record);
    }

    Writer.AddTypeRef(D->getCommonPtr()->InjectedClassNameType, Record);
  }
  Code = serialization::DECL_CLASS_TEMPLATE;
}

void ASTDeclWriter::VisitClassTemplateSpecializationDecl(
                                           ClassTemplateSpecializationDecl *D) {
  VisitCXXRecordDecl(D);

  llvm::PointerUnion<ClassTemplateDecl *,
                     ClassTemplatePartialSpecializationDecl *> InstFrom
    = D->getSpecializedTemplateOrPartial();
  if (Decl *InstFromD = InstFrom.dyn_cast<ClassTemplateDecl *>()) {
    Writer.AddDeclRef(InstFromD, Record);
  } else {
    Writer.AddDeclRef(InstFrom.get<ClassTemplatePartialSpecializationDecl *>(),
                      Record);
    Writer.AddTemplateArgumentList(&D->getTemplateInstantiationArgs(), Record);
  }

  // Explicit info.
  Writer.AddTypeSourceInfo(D->getTypeAsWritten(), Record);
  if (D->getTypeAsWritten()) {
    Writer.AddSourceLocation(D->getExternLoc(), Record);
    Writer.AddSourceLocation(D->getTemplateKeywordLoc(), Record);
  }

  Writer.AddTemplateArgumentList(&D->getTemplateArgs(), Record);
  Writer.AddSourceLocation(D->getPointOfInstantiation(), Record);
  Record.push_back(D->getSpecializationKind());
  Record.push_back(D->isCanonicalDecl());

  if (D->isCanonicalDecl()) {
    // When reading, we'll add it to the folding set of the following template.
    Writer.AddDeclRef(D->getSpecializedTemplate()->getCanonicalDecl(), Record);
  }

  Code = serialization::DECL_CLASS_TEMPLATE_SPECIALIZATION;
}

void ASTDeclWriter::VisitClassTemplatePartialSpecializationDecl(
                                    ClassTemplatePartialSpecializationDecl *D) {
  VisitClassTemplateSpecializationDecl(D);

  Writer.AddTemplateParameterList(D->getTemplateParameters(), Record);

  Record.push_back(D->getNumTemplateArgsAsWritten());
  for (int i = 0, e = D->getNumTemplateArgsAsWritten(); i != e; ++i)
    Writer.AddTemplateArgumentLoc(D->getTemplateArgsAsWritten()[i], Record);

  Record.push_back(D->getSequenceNumber());

  // These are read/set from/to the first declaration.
  if (D->getPreviousDecl() == 0) {
    Writer.AddDeclRef(D->getInstantiatedFromMember(), Record);
    Record.push_back(D->isMemberSpecialization());
  }

  Code = serialization::DECL_CLASS_TEMPLATE_PARTIAL_SPECIALIZATION;
}

void ASTDeclWriter::VisitClassScopeFunctionSpecializationDecl(
                                    ClassScopeFunctionSpecializationDecl *D) {
  VisitDecl(D);
  Writer.AddDeclRef(D->getSpecialization(), Record);
  Code = serialization::DECL_CLASS_SCOPE_FUNCTION_SPECIALIZATION;
}


void ASTDeclWriter::VisitFunctionTemplateDecl(FunctionTemplateDecl *D) {
  VisitRedeclarableTemplateDecl(D);

  if (D->isFirstDeclaration()) {
    // This FunctionTemplateDecl owns the CommonPtr; write it.

    // Write the function specialization declarations.
    Record.push_back(D->getSpecializations().size());
    for (llvm::FoldingSetVector<FunctionTemplateSpecializationInfo>::iterator
           I = D->getSpecializations().begin(),
           E = D->getSpecializations().end()   ; I != E; ++I) {
      assert(I->Function->isCanonicalDecl() &&
             "Expected only canonical decls in set");
      Writer.AddDeclRef(I->Function, Record);
    }
  }
  Code = serialization::DECL_FUNCTION_TEMPLATE;
}

void ASTDeclWriter::VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D) {
  VisitTypeDecl(D);

  Record.push_back(D->wasDeclaredWithTypename());
  Record.push_back(D->defaultArgumentWasInherited());
  Writer.AddTypeSourceInfo(D->getDefaultArgumentInfo(), Record);

  Code = serialization::DECL_TEMPLATE_TYPE_PARM;
}

void ASTDeclWriter::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
  // For an expanded parameter pack, record the number of expansion types here
  // so that it's easier for deserialization to allocate the right amount of
  // memory.
  if (D->isExpandedParameterPack())
    Record.push_back(D->getNumExpansionTypes());

  VisitDeclaratorDecl(D);
  // TemplateParmPosition.
  Record.push_back(D->getDepth());
  Record.push_back(D->getPosition());

  if (D->isExpandedParameterPack()) {
    for (unsigned I = 0, N = D->getNumExpansionTypes(); I != N; ++I) {
      Writer.AddTypeRef(D->getExpansionType(I), Record);
      Writer.AddTypeSourceInfo(D->getExpansionTypeSourceInfo(I), Record);
    }

    Code = serialization::DECL_EXPANDED_NON_TYPE_TEMPLATE_PARM_PACK;
  } else {
    // Rest of NonTypeTemplateParmDecl.
    Record.push_back(D->isParameterPack());
    Record.push_back(D->getDefaultArgument() != 0);
    if (D->getDefaultArgument()) {
      Writer.AddStmt(D->getDefaultArgument());
      Record.push_back(D->defaultArgumentWasInherited());
    }
    Code = serialization::DECL_NON_TYPE_TEMPLATE_PARM;
  }
}

void ASTDeclWriter::VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D) {
  // For an expanded parameter pack, record the number of expansion types here
  // so that it's easier for deserialization to allocate the right amount of
  // memory.
  if (D->isExpandedParameterPack())
    Record.push_back(D->getNumExpansionTemplateParameters());

  VisitTemplateDecl(D);
  // TemplateParmPosition.
  Record.push_back(D->getDepth());
  Record.push_back(D->getPosition());

  if (D->isExpandedParameterPack()) {
    for (unsigned I = 0, N = D->getNumExpansionTemplateParameters();
         I != N; ++I)
      Writer.AddTemplateParameterList(D->getExpansionTemplateParameters(I),
                                      Record);
    Code = serialization::DECL_EXPANDED_TEMPLATE_TEMPLATE_PARM_PACK;
  } else {
    // Rest of TemplateTemplateParmDecl.
    Writer.AddTemplateArgumentLoc(D->getDefaultArgument(), Record);
    Record.push_back(D->defaultArgumentWasInherited());
    Record.push_back(D->isParameterPack());
    Code = serialization::DECL_TEMPLATE_TEMPLATE_PARM;
  }
}

void ASTDeclWriter::VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D) {
  VisitRedeclarableTemplateDecl(D);
  Code = serialization::DECL_TYPE_ALIAS_TEMPLATE;
}

void ASTDeclWriter::VisitStaticAssertDecl(StaticAssertDecl *D) {
  VisitDecl(D);
  Writer.AddStmt(D->getAssertExpr());
  Record.push_back(D->isFailed());
  Writer.AddStmt(D->getMessage());
  Writer.AddSourceLocation(D->getRParenLoc(), Record);
  Code = serialization::DECL_STATIC_ASSERT;
}

/// \brief Emit the DeclContext part of a declaration context decl.
///
/// \param LexicalOffset the offset at which the DECL_CONTEXT_LEXICAL
/// block for this declaration context is stored. May be 0 to indicate
/// that there are no declarations stored within this context.
///
/// \param VisibleOffset the offset at which the DECL_CONTEXT_VISIBLE
/// block for this declaration context is stored. May be 0 to indicate
/// that there are no declarations visible from this context. Note
/// that this value will not be emitted for non-primary declaration
/// contexts.
void ASTDeclWriter::VisitDeclContext(DeclContext *DC, uint64_t LexicalOffset,
                                     uint64_t VisibleOffset) {
  Record.push_back(LexicalOffset);
  Record.push_back(VisibleOffset);
}

template <typename T>
void ASTDeclWriter::VisitRedeclarable(Redeclarable<T> *D) {
  T *First = D->getFirstDeclaration();
  if (First->getMostRecentDecl() != First) {
    assert(isRedeclarableDeclKind(static_cast<T *>(D)->getKind()) &&
           "Not considered redeclarable?");

    // There is more than one declaration of this entity, so we will need to
    // write a redeclaration chain.
    Writer.AddDeclRef(First, Record);
    Writer.Redeclarations.insert(First);

    // Make sure that we serialize both the previous and the most-recent
    // declarations, which (transitively) ensures that all declarations in the
    // chain get serialized.
    (void)Writer.GetDeclRef(D->getPreviousDecl());
    (void)Writer.GetDeclRef(First->getMostRecentDecl());
  } else {
    // We use the sentinel value 0 to indicate an only declaration.
    Record.push_back(0);
  }

}

//===----------------------------------------------------------------------===//
// ASTWriter Implementation
//===----------------------------------------------------------------------===//

void ASTWriter::WriteDeclsBlockAbbrevs() {
  using namespace llvm;

  BitCodeAbbrev *Abv;

  // Abbreviation for DECL_FIELD
  Abv = new BitCodeAbbrev();
  Abv->Add(BitCodeAbbrevOp(serialization::DECL_FIELD));
  // Decl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
  Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
  Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
  Abv->Add(BitCodeAbbrevOp(0));                       // isReferenced
  Abv->Add(BitCodeAbbrevOp(0));                   // TopLevelDeclInObjCContainer
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2));  // AccessSpecifier
  Abv->Add(BitCodeAbbrevOp(0));                       // ModulePrivate
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
  // NamedDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
  // ValueDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
  // DeclaratorDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // InnerStartLoc
  Abv->Add(BitCodeAbbrevOp(0));                       // hasExtInfo
  // FieldDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isMutable
  Abv->Add(BitCodeAbbrevOp(0));                       //getBitWidth
  // Type Source Info
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TypeLoc
  DeclFieldAbbrev = Stream.EmitAbbrev(Abv);

  // Abbreviation for DECL_OBJC_IVAR
  Abv = new BitCodeAbbrev();
  Abv->Add(BitCodeAbbrevOp(serialization::DECL_OBJC_IVAR));
  // Decl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
  Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
  Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
  Abv->Add(BitCodeAbbrevOp(0));                       // isReferenced
  Abv->Add(BitCodeAbbrevOp(0));                   // TopLevelDeclInObjCContainer
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2));  // AccessSpecifier
  Abv->Add(BitCodeAbbrevOp(0));                       // ModulePrivate
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
  // NamedDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
  // ValueDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
  // DeclaratorDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // InnerStartLoc
  Abv->Add(BitCodeAbbrevOp(0));                       // hasExtInfo
  // FieldDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isMutable
  Abv->Add(BitCodeAbbrevOp(0));                       //getBitWidth
  // ObjC Ivar
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // getAccessControl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // getSynthesize
  // Type Source Info
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TypeLoc
  DeclObjCIvarAbbrev = Stream.EmitAbbrev(Abv);

  // Abbreviation for DECL_ENUM
  Abv = new BitCodeAbbrev();
  Abv->Add(BitCodeAbbrevOp(serialization::DECL_ENUM));
  // Redeclarable
  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
  // Decl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
  Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
  Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
  Abv->Add(BitCodeAbbrevOp(0));                       // isReferenced
  Abv->Add(BitCodeAbbrevOp(0));                   // TopLevelDeclInObjCContainer
  Abv->Add(BitCodeAbbrevOp(AS_none));                 // C++ AccessSpecifier
  Abv->Add(BitCodeAbbrevOp(0));                       // ModulePrivate
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
  // NamedDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
  // TypeDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type Ref
  // TagDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // IdentifierNamespace
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // getTagKind
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isCompleteDefinition
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // EmbeddedInDeclarator
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // IsFreeStanding
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // SourceLocation
  Abv->Add(BitCodeAbbrevOp(0));                         // hasExtInfo
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // TypedefNameAnonDecl
  // EnumDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddTypeRef
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // IntegerType
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // getPromotionType
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // getNumPositiveBits
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // getNumNegativeBits
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isScoped
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isScopedUsingClassTag
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isFixed
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // InstantiatedMembEnum
  // DC
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // LexicalOffset
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // VisibleOffset
  DeclEnumAbbrev = Stream.EmitAbbrev(Abv);

  // Abbreviation for DECL_RECORD
  Abv = new BitCodeAbbrev();
  Abv->Add(BitCodeAbbrevOp(serialization::DECL_RECORD));
  // Redeclarable
  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
  // Decl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
  Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
  Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
  Abv->Add(BitCodeAbbrevOp(0));                       // isReferenced
  Abv->Add(BitCodeAbbrevOp(0));                   // TopLevelDeclInObjCContainer
  Abv->Add(BitCodeAbbrevOp(AS_none));                 // C++ AccessSpecifier
  Abv->Add(BitCodeAbbrevOp(0));                       // ModulePrivate
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
  // NamedDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
  // TypeDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type Ref
  // TagDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // IdentifierNamespace
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // getTagKind
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isCompleteDefinition
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // EmbeddedInDeclarator
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // IsFreeStanding
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // SourceLocation
  Abv->Add(BitCodeAbbrevOp(0));                         // hasExtInfo
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // TypedefNameAnonDecl
  // RecordDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // FlexibleArrayMember
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // AnonymousStructUnion
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // hasObjectMember
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // hasVolatileMember
  // DC
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // LexicalOffset
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // VisibleOffset
  DeclRecordAbbrev = Stream.EmitAbbrev(Abv);

  // Abbreviation for DECL_PARM_VAR
  Abv = new BitCodeAbbrev();
  Abv->Add(BitCodeAbbrevOp(serialization::DECL_PARM_VAR));
  // Redeclarable
  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
  // Decl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
  Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
  Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
  Abv->Add(BitCodeAbbrevOp(0));                       // isReferenced
  Abv->Add(BitCodeAbbrevOp(0));                   // TopLevelDeclInObjCContainer
  Abv->Add(BitCodeAbbrevOp(AS_none));                 // C++ AccessSpecifier
  Abv->Add(BitCodeAbbrevOp(0));                       // ModulePrivate
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
  // NamedDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
  // ValueDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
  // DeclaratorDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // InnerStartLoc
  Abv->Add(BitCodeAbbrevOp(0));                       // hasExtInfo
  // VarDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // StorageClass
  Abv->Add(BitCodeAbbrevOp(0));                       // StorageClassAsWritten
  Abv->Add(BitCodeAbbrevOp(0));                       // isThreadSpecified
  Abv->Add(BitCodeAbbrevOp(0));                       // hasCXXDirectInitializer
  Abv->Add(BitCodeAbbrevOp(0));                       // isExceptionVariable
  Abv->Add(BitCodeAbbrevOp(0));                       // isNRVOVariable
  Abv->Add(BitCodeAbbrevOp(0));                       // isCXXForRangeDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // isARCPseudoStrong
  Abv->Add(BitCodeAbbrevOp(0));                       // isConstexpr
  Abv->Add(BitCodeAbbrevOp(0));                       // HasInit
  Abv->Add(BitCodeAbbrevOp(0));                   // HasMemberSpecializationInfo
  // ParmVarDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // IsObjCMethodParameter
  Abv->Add(BitCodeAbbrevOp(0));                       // ScopeDepth
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ScopeIndex
  Abv->Add(BitCodeAbbrevOp(0));                       // ObjCDeclQualifier
  Abv->Add(BitCodeAbbrevOp(0));                       // KNRPromoted
  Abv->Add(BitCodeAbbrevOp(0));                       // HasInheritedDefaultArg
  Abv->Add(BitCodeAbbrevOp(0));                   // HasUninstantiatedDefaultArg
  // Type Source Info
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TypeLoc
  DeclParmVarAbbrev = Stream.EmitAbbrev(Abv);

  // Abbreviation for DECL_TYPEDEF
  Abv = new BitCodeAbbrev();
  Abv->Add(BitCodeAbbrevOp(serialization::DECL_TYPEDEF));
  // Redeclarable
  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
  // Decl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
  Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
  Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
  Abv->Add(BitCodeAbbrevOp(0));                       // isReferenced
  Abv->Add(BitCodeAbbrevOp(0));                   // TopLevelDeclInObjCContainer
  Abv->Add(BitCodeAbbrevOp(AS_none));                 // C++ AccessSpecifier
  Abv->Add(BitCodeAbbrevOp(0));                       // ModulePrivate
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
  // NamedDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
  // TypeDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type Ref
  // TypedefDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TypeLoc
  DeclTypedefAbbrev = Stream.EmitAbbrev(Abv);

  // Abbreviation for DECL_VAR
  Abv = new BitCodeAbbrev();
  Abv->Add(BitCodeAbbrevOp(serialization::DECL_VAR));
  // Redeclarable
  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
  // Decl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
  Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
  Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
  Abv->Add(BitCodeAbbrevOp(0));                       // isReferenced
  Abv->Add(BitCodeAbbrevOp(0));                   // TopLevelDeclInObjCContainer
  Abv->Add(BitCodeAbbrevOp(AS_none));                 // C++ AccessSpecifier
  Abv->Add(BitCodeAbbrevOp(0));                       // ModulePrivate
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
  // NamedDecl
  Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
  // ValueDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
  // DeclaratorDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // InnerStartLoc
  Abv->Add(BitCodeAbbrevOp(0));                       // hasExtInfo
  // VarDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // StorageClass
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // StorageClassAsWritten
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isThreadSpecified
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // CXXDirectInitializer
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isExceptionVariable
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isNRVOVariable
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isCXXForRangeDecl
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isARCPseudoStrong
  Abv->Add(BitCodeAbbrevOp(0));                         // isConstexpr
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // HasInit
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // HasMemberSpecInfo
  // Type Source Info
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TypeLoc
  DeclVarAbbrev = Stream.EmitAbbrev(Abv);

  // Abbreviation for EXPR_DECL_REF
  Abv = new BitCodeAbbrev();
  Abv->Add(BitCodeAbbrevOp(serialization::EXPR_DECL_REF));
  //Stmt
  //Expr
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //TypeDependent
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //ValueDependent
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //InstantiationDependent
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //UnexpandedParamPack
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); //GetValueKind
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); //GetObjectKind
  //DeclRefExpr
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //HasQualifier
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //GetDeclFound
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //ExplicitTemplateArgs
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //HadMultipleCandidates
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //RefersToEnclosingLocal
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclRef
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Location
  DeclRefExprAbbrev = Stream.EmitAbbrev(Abv);

  // Abbreviation for EXPR_INTEGER_LITERAL
  Abv = new BitCodeAbbrev();
  Abv->Add(BitCodeAbbrevOp(serialization::EXPR_INTEGER_LITERAL));
  //Stmt
  //Expr
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //TypeDependent
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //ValueDependent
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //InstantiationDependent
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //UnexpandedParamPack
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); //GetValueKind
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); //GetObjectKind
  //Integer Literal
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Location
  Abv->Add(BitCodeAbbrevOp(32));                      // Bit Width
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Value
  IntegerLiteralAbbrev = Stream.EmitAbbrev(Abv);

  // Abbreviation for EXPR_CHARACTER_LITERAL
  Abv = new BitCodeAbbrev();
  Abv->Add(BitCodeAbbrevOp(serialization::EXPR_CHARACTER_LITERAL));
  //Stmt
  //Expr
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //TypeDependent
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //ValueDependent
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //InstantiationDependent
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //UnexpandedParamPack
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); //GetValueKind
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); //GetObjectKind
  //Character Literal
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // getValue
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Location
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2)); // getKind
  CharacterLiteralAbbrev = Stream.EmitAbbrev(Abv);

  Abv = new BitCodeAbbrev();
  Abv->Add(BitCodeAbbrevOp(serialization::DECL_CONTEXT_LEXICAL));
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
  DeclContextLexicalAbbrev = Stream.EmitAbbrev(Abv);

  Abv = new BitCodeAbbrev();
  Abv->Add(BitCodeAbbrevOp(serialization::DECL_CONTEXT_VISIBLE));
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
  DeclContextVisibleLookupAbbrev = Stream.EmitAbbrev(Abv);
}

/// isRequiredDecl - Check if this is a "required" Decl, which must be seen by
/// consumers of the AST.
///
/// Such decls will always be deserialized from the AST file, so we would like
/// this to be as restrictive as possible. Currently the predicate is driven by
/// code generation requirements, if other clients have a different notion of
/// what is "required" then we may have to consider an alternate scheme where
/// clients can iterate over the top-level decls and get information on them,
/// without necessary deserializing them. We could explicitly require such
/// clients to use a separate API call to "realize" the decl. This should be
/// relatively painless since they would presumably only do it for top-level
/// decls.
static bool isRequiredDecl(const Decl *D, ASTContext &Context) {
  // An ObjCMethodDecl is never considered as "required" because its
  // implementation container always is.

  // File scoped assembly or obj-c implementation must be seen.
  if (isa<FileScopeAsmDecl>(D) || isa<ObjCImplDecl>(D))
    return true;

  return Context.DeclMustBeEmitted(D);
}

void ASTWriter::WriteDecl(ASTContext &Context, Decl *D) {
  // Switch case IDs are per Decl.
  ClearSwitchCaseIDs();

  RecordData Record;
  ASTDeclWriter W(*this, Context, Record);

  // Determine the ID for this declaration.
  serialization::DeclID ID;
  if (D->isFromASTFile())
    ID = getDeclID(D);
  else {
    serialization::DeclID &IDR = DeclIDs[D];
    if (IDR == 0)
      IDR = NextDeclID++;

    ID= IDR;
  }

  bool isReplacingADecl = ID < FirstDeclID;

  // If this declaration is also a DeclContext, write blocks for the
  // declarations that lexically stored inside its context and those
  // declarations that are visible from its context. These blocks
  // are written before the declaration itself so that we can put
  // their offsets into the record for the declaration.
  uint64_t LexicalOffset = 0;
  uint64_t VisibleOffset = 0;
  DeclContext *DC = dyn_cast<DeclContext>(D);
  if (DC) {
    if (isReplacingADecl) {
      // It is replacing a decl from a chained PCH; make sure that the
      // DeclContext is fully loaded.
      if (DC->hasExternalLexicalStorage())
        DC->LoadLexicalDeclsFromExternalStorage();
      if (DC->hasExternalVisibleStorage())
        Chain->completeVisibleDeclsMap(DC);
    }
    LexicalOffset = WriteDeclContextLexicalBlock(Context, DC);
    VisibleOffset = WriteDeclContextVisibleBlock(Context, DC);
  }

  if (isReplacingADecl) {
    // We're replacing a decl in a previous file.
    ReplacedDecls.push_back(ReplacedDeclInfo(ID, Stream.GetCurrentBitNo(),
                                             D->getLocation()));
  } else {
    unsigned Index = ID - FirstDeclID;

    // Record the offset for this declaration
    SourceLocation Loc = D->getLocation();
    if (DeclOffsets.size() == Index)
      DeclOffsets.push_back(DeclOffset(Loc, Stream.GetCurrentBitNo()));
    else if (DeclOffsets.size() < Index) {
      DeclOffsets.resize(Index+1);
      DeclOffsets[Index].setLocation(Loc);
      DeclOffsets[Index].BitOffset = Stream.GetCurrentBitNo();
    }

    SourceManager &SM = Context.getSourceManager();
    if (Loc.isValid() && SM.isLocalSourceLocation(Loc))
      associateDeclWithFile(D, ID);
  }

  // Build and emit a record for this declaration
  Record.clear();
  W.Code = (serialization::DeclCode)0;
  W.AbbrevToUse = 0;
  W.Visit(D);
  if (DC) W.VisitDeclContext(DC, LexicalOffset, VisibleOffset);

  if (!W.Code)
    llvm::report_fatal_error(StringRef("unexpected declaration kind '") +
                            D->getDeclKindName() + "'");
  Stream.EmitRecord(W.Code, Record, W.AbbrevToUse);

  // Flush any expressions that were written as part of this declaration.
  FlushStmts();

  // Flush C++ base specifiers, if there are any.
  FlushCXXBaseSpecifiers();

  // Note "external" declarations so that we can add them to a record in the
  // AST file later.
  //
  // FIXME: This should be renamed, the predicate is much more complicated.
  if (isRequiredDecl(D, Context))
    ExternalDefinitions.push_back(ID);
}