lib/Serialization/ASTWriter.cpp

//===--- ASTWriter.cpp - AST File Writer ----------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file defines the ASTWriter class, which writes AST files.
//
//===----------------------------------------------------------------------===//

#include "clang/Serialization/ASTWriter.h"
#include "ASTCommon.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclContextInternals.h"
#include "clang/AST/DeclFriend.h"
#include "clang/AST/DeclLookups.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/Type.h"
#include "clang/AST/TypeLocVisitor.h"
#include "clang/Basic/FileManager.h"
#include "clang/Basic/FileSystemStatCache.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/SourceManagerInternals.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Basic/TargetOptions.h"
#include "clang/Basic/Version.h"
#include "clang/Basic/VersionTuple.h"
#include "clang/Lex/HeaderSearch.h"
#include "clang/Lex/HeaderSearchOptions.h"
#include "clang/Lex/MacroInfo.h"
#include "clang/Lex/PreprocessingRecord.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Lex/PreprocessorOptions.h"
#include "clang/Sema/IdentifierResolver.h"
#include "clang/Sema/Sema.h"
#include "clang/Serialization/ASTReader.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Bitcode/BitstreamWriter.h"
#include "llvm/Support/EndianStream.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/OnDiskHashTable.h"
#include "llvm/Support/Path.h"
#include <algorithm>
#include <cstdio>
#include <string.h>
#include <utility>
using namespace clang;
using namespace clang::serialization;

template <typename T, typename Allocator>
static StringRef data(const std::vector<T, Allocator> &v) {
  if (v.empty()) return StringRef();
  return StringRef(reinterpret_cast<const char*>(&v[0]),
                         sizeof(T) * v.size());
}

template <typename T>
static StringRef data(const SmallVectorImpl<T> &v) {
  return StringRef(reinterpret_cast<const char*>(v.data()),
                         sizeof(T) * v.size());
}

//===----------------------------------------------------------------------===//
// Type serialization
//===----------------------------------------------------------------------===//

namespace {
  class ASTTypeWriter {
    ASTWriter &Writer;
    ASTWriter::RecordDataImpl &Record;

  public:
    /// \brief Type code that corresponds to the record generated.
    TypeCode Code;

    ASTTypeWriter(ASTWriter &Writer, ASTWriter::RecordDataImpl &Record)
      : Writer(Writer), Record(Record), Code(TYPE_EXT_QUAL) { }

    void VisitArrayType(const ArrayType *T);
    void VisitFunctionType(const FunctionType *T);
    void VisitTagType(const TagType *T);

#define TYPE(Class, Base) void Visit##Class##Type(const Class##Type *T);
#define ABSTRACT_TYPE(Class, Base)
#include "clang/AST/TypeNodes.def"
  };
}

void ASTTypeWriter::VisitBuiltinType(const BuiltinType *T) {
  llvm_unreachable("Built-in types are never serialized");
}

void ASTTypeWriter::VisitComplexType(const ComplexType *T) {
  Writer.AddTypeRef(T->getElementType(), Record);
  Code = TYPE_COMPLEX;
}

void ASTTypeWriter::VisitPointerType(const PointerType *T) {
  Writer.AddTypeRef(T->getPointeeType(), Record);
  Code = TYPE_POINTER;
}

void ASTTypeWriter::VisitDecayedType(const DecayedType *T) {
  Writer.AddTypeRef(T->getOriginalType(), Record);
  Code = TYPE_DECAYED;
}

void ASTTypeWriter::VisitAdjustedType(const AdjustedType *T) {
  Writer.AddTypeRef(T->getOriginalType(), Record);
  Writer.AddTypeRef(T->getAdjustedType(), Record);
  Code = TYPE_ADJUSTED;
}

void ASTTypeWriter::VisitBlockPointerType(const BlockPointerType *T) {
  Writer.AddTypeRef(T->getPointeeType(), Record);
  Code = TYPE_BLOCK_POINTER;
}

void ASTTypeWriter::VisitLValueReferenceType(const LValueReferenceType *T) {
  Writer.AddTypeRef(T->getPointeeTypeAsWritten(), Record);
  Record.push_back(T->isSpelledAsLValue());
  Code = TYPE_LVALUE_REFERENCE;
}

void ASTTypeWriter::VisitRValueReferenceType(const RValueReferenceType *T) {
  Writer.AddTypeRef(T->getPointeeTypeAsWritten(), Record);
  Code = TYPE_RVALUE_REFERENCE;
}

void ASTTypeWriter::VisitMemberPointerType(const MemberPointerType *T) {
  Writer.AddTypeRef(T->getPointeeType(), Record);
  Writer.AddTypeRef(QualType(T->getClass(), 0), Record);
  Code = TYPE_MEMBER_POINTER;
}

void ASTTypeWriter::VisitArrayType(const ArrayType *T) {
  Writer.AddTypeRef(T->getElementType(), Record);
  Record.push_back(T->getSizeModifier()); // FIXME: stable values
  Record.push_back(T->getIndexTypeCVRQualifiers()); // FIXME: stable values
}

void ASTTypeWriter::VisitConstantArrayType(const ConstantArrayType *T) {
  VisitArrayType(T);
  Writer.AddAPInt(T->getSize(), Record);
  Code = TYPE_CONSTANT_ARRAY;
}

void ASTTypeWriter::VisitIncompleteArrayType(const IncompleteArrayType *T) {
  VisitArrayType(T);
  Code = TYPE_INCOMPLETE_ARRAY;
}

void ASTTypeWriter::VisitVariableArrayType(const VariableArrayType *T) {
  VisitArrayType(T);
  Writer.AddSourceLocation(T->getLBracketLoc(), Record);
  Writer.AddSourceLocation(T->getRBracketLoc(), Record);
  Writer.AddStmt(T->getSizeExpr());
  Code = TYPE_VARIABLE_ARRAY;
}

void ASTTypeWriter::VisitVectorType(const VectorType *T) {
  Writer.AddTypeRef(T->getElementType(), Record);
  Record.push_back(T->getNumElements());
  Record.push_back(T->getVectorKind());
  Code = TYPE_VECTOR;
}

void ASTTypeWriter::VisitExtVectorType(const ExtVectorType *T) {
  VisitVectorType(T);
  Code = TYPE_EXT_VECTOR;
}

void ASTTypeWriter::VisitFunctionType(const FunctionType *T) {
  Writer.AddTypeRef(T->getReturnType(), Record);
  FunctionType::ExtInfo C = T->getExtInfo();
  Record.push_back(C.getNoReturn());
  Record.push_back(C.getHasRegParm());
  Record.push_back(C.getRegParm());
  // FIXME: need to stabilize encoding of calling convention...
  Record.push_back(C.getCC());
  Record.push_back(C.getProducesResult());
}

void ASTTypeWriter::VisitFunctionNoProtoType(const FunctionNoProtoType *T) {
  VisitFunctionType(T);
  Code = TYPE_FUNCTION_NO_PROTO;
}

static void addExceptionSpec(ASTWriter &Writer, const FunctionProtoType *T,
                             ASTWriter::RecordDataImpl &Record) {
  Record.push_back(T->getExceptionSpecType());
  if (T->getExceptionSpecType() == EST_Dynamic) {
    Record.push_back(T->getNumExceptions());
    for (unsigned I = 0, N = T->getNumExceptions(); I != N; ++I)
      Writer.AddTypeRef(T->getExceptionType(I), Record);
  } else if (T->getExceptionSpecType() == EST_ComputedNoexcept) {
    Writer.AddStmt(T->getNoexceptExpr());
  } else if (T->getExceptionSpecType() == EST_Uninstantiated) {
    Writer.AddDeclRef(T->getExceptionSpecDecl(), Record);
    Writer.AddDeclRef(T->getExceptionSpecTemplate(), Record);
  } else if (T->getExceptionSpecType() == EST_Unevaluated) {
    Writer.AddDeclRef(T->getExceptionSpecDecl(), Record);
  }
}

void ASTTypeWriter::VisitFunctionProtoType(const FunctionProtoType *T) {
  VisitFunctionType(T);
  Record.push_back(T->getNumParams());
  for (unsigned I = 0, N = T->getNumParams(); I != N; ++I)
    Writer.AddTypeRef(T->getParamType(I), Record);
  Record.push_back(T->isVariadic());
  Record.push_back(T->hasTrailingReturn());
  Record.push_back(T->getTypeQuals());
  Record.push_back(static_cast<unsigned>(T->getRefQualifier()));
  addExceptionSpec(Writer, T, Record);
  Code = TYPE_FUNCTION_PROTO;
}

void ASTTypeWriter::VisitUnresolvedUsingType(const UnresolvedUsingType *T) {
  Writer.AddDeclRef(T->getDecl(), Record);
  Code = TYPE_UNRESOLVED_USING;
}

void ASTTypeWriter::VisitTypedefType(const TypedefType *T) {
  Writer.AddDeclRef(T->getDecl(), Record);
  assert(!T->isCanonicalUnqualified() && "Invalid typedef ?");
  Writer.AddTypeRef(T->getCanonicalTypeInternal(), Record);
  Code = TYPE_TYPEDEF;
}

void ASTTypeWriter::VisitTypeOfExprType(const TypeOfExprType *T) {
  Writer.AddStmt(T->getUnderlyingExpr());
  Code = TYPE_TYPEOF_EXPR;
}

void ASTTypeWriter::VisitTypeOfType(const TypeOfType *T) {
  Writer.AddTypeRef(T->getUnderlyingType(), Record);
  Code = TYPE_TYPEOF;
}

void ASTTypeWriter::VisitDecltypeType(const DecltypeType *T) {
  Writer.AddTypeRef(T->getUnderlyingType(), Record);
  Writer.AddStmt(T->getUnderlyingExpr());
  Code = TYPE_DECLTYPE;
}

void ASTTypeWriter::VisitUnaryTransformType(const UnaryTransformType *T) {
  Writer.AddTypeRef(T->getBaseType(), Record);
  Writer.AddTypeRef(T->getUnderlyingType(), Record);
  Record.push_back(T->getUTTKind());
  Code = TYPE_UNARY_TRANSFORM;
}

void ASTTypeWriter::VisitAutoType(const AutoType *T) {
  Writer.AddTypeRef(T->getDeducedType(), Record);
  Record.push_back(T->isDecltypeAuto());
  if (T->getDeducedType().isNull())
    Record.push_back(T->isDependentType());
  Code = TYPE_AUTO;
}

void ASTTypeWriter::VisitTagType(const TagType *T) {
  Record.push_back(T->isDependentType());
  Writer.AddDeclRef(T->getDecl()->getCanonicalDecl(), Record);
  assert(!T->isBeingDefined() &&
         "Cannot serialize in the middle of a type definition");
}

void ASTTypeWriter::VisitRecordType(const RecordType *T) {
  VisitTagType(T);
  Code = TYPE_RECORD;
}

void ASTTypeWriter::VisitEnumType(const EnumType *T) {
  VisitTagType(T);
  Code = TYPE_ENUM;
}

void ASTTypeWriter::VisitAttributedType(const AttributedType *T) {
  Writer.AddTypeRef(T->getModifiedType(), Record);
  Writer.AddTypeRef(T->getEquivalentType(), Record);
  Record.push_back(T->getAttrKind());
  Code = TYPE_ATTRIBUTED;
}

void
ASTTypeWriter::VisitSubstTemplateTypeParmType(
                                        const SubstTemplateTypeParmType *T) {
  Writer.AddTypeRef(QualType(T->getReplacedParameter(), 0), Record);
  Writer.AddTypeRef(T->getReplacementType(), Record);
  Code = TYPE_SUBST_TEMPLATE_TYPE_PARM;
}

void
ASTTypeWriter::VisitSubstTemplateTypeParmPackType(
                                      const SubstTemplateTypeParmPackType *T) {
  Writer.AddTypeRef(QualType(T->getReplacedParameter(), 0), Record);
  Writer.AddTemplateArgument(T->getArgumentPack(), Record);
  Code = TYPE_SUBST_TEMPLATE_TYPE_PARM_PACK;
}

void
ASTTypeWriter::VisitTemplateSpecializationType(
                                       const TemplateSpecializationType *T) {
  Record.push_back(T->isDependentType());
  Writer.AddTemplateName(T->getTemplateName(), Record);
  Record.push_back(T->getNumArgs());
  for (TemplateSpecializationType::iterator ArgI = T->begin(), ArgE = T->end();
         ArgI != ArgE; ++ArgI)
    Writer.AddTemplateArgument(*ArgI, Record);
  Writer.AddTypeRef(T->isTypeAlias() ? T->getAliasedType() :
                    T->isCanonicalUnqualified() ? QualType()
                                                : T->getCanonicalTypeInternal(),
                    Record);
  Code = TYPE_TEMPLATE_SPECIALIZATION;
}

void
ASTTypeWriter::VisitDependentSizedArrayType(const DependentSizedArrayType *T) {
  VisitArrayType(T);
  Writer.AddStmt(T->getSizeExpr());
  Writer.AddSourceRange(T->getBracketsRange(), Record);
  Code = TYPE_DEPENDENT_SIZED_ARRAY;
}

void
ASTTypeWriter::VisitDependentSizedExtVectorType(
                                        const DependentSizedExtVectorType *T) {
  // FIXME: Serialize this type (C++ only)
  llvm_unreachable("Cannot serialize dependent sized extended vector types");
}

void
ASTTypeWriter::VisitTemplateTypeParmType(const TemplateTypeParmType *T) {
  Record.push_back(T->getDepth());
  Record.push_back(T->getIndex());
  Record.push_back(T->isParameterPack());
  Writer.AddDeclRef(T->getDecl(), Record);
  Code = TYPE_TEMPLATE_TYPE_PARM;
}

void
ASTTypeWriter::VisitDependentNameType(const DependentNameType *T) {
  Record.push_back(T->getKeyword());
  Writer.AddNestedNameSpecifier(T->getQualifier(), Record);
  Writer.AddIdentifierRef(T->getIdentifier(), Record);
  Writer.AddTypeRef(T->isCanonicalUnqualified() ? QualType()
                                                : T->getCanonicalTypeInternal(),
                    Record);
  Code = TYPE_DEPENDENT_NAME;
}

void
ASTTypeWriter::VisitDependentTemplateSpecializationType(
                                const DependentTemplateSpecializationType *T) {
  Record.push_back(T->getKeyword());
  Writer.AddNestedNameSpecifier(T->getQualifier(), Record);
  Writer.AddIdentifierRef(T->getIdentifier(), Record);
  Record.push_back(T->getNumArgs());
  for (DependentTemplateSpecializationType::iterator
         I = T->begin(), E = T->end(); I != E; ++I)
    Writer.AddTemplateArgument(*I, Record);
  Code = TYPE_DEPENDENT_TEMPLATE_SPECIALIZATION;
}

void ASTTypeWriter::VisitPackExpansionType(const PackExpansionType *T) {
  Writer.AddTypeRef(T->getPattern(), Record);
  if (Optional<unsigned> NumExpansions = T->getNumExpansions())
    Record.push_back(*NumExpansions + 1);
  else
    Record.push_back(0);
  Code = TYPE_PACK_EXPANSION;
}

void ASTTypeWriter::VisitParenType(const ParenType *T) {
  Writer.AddTypeRef(T->getInnerType(), Record);
  Code = TYPE_PAREN;
}

void ASTTypeWriter::VisitElaboratedType(const ElaboratedType *T) {
  Record.push_back(T->getKeyword());
  Writer.AddNestedNameSpecifier(T->getQualifier(), Record);
  Writer.AddTypeRef(T->getNamedType(), Record);
  Code = TYPE_ELABORATED;
}

void ASTTypeWriter::VisitInjectedClassNameType(const InjectedClassNameType *T) {
  Writer.AddDeclRef(T->getDecl()->getCanonicalDecl(), Record);
  Writer.AddTypeRef(T->getInjectedSpecializationType(), Record);
  Code = TYPE_INJECTED_CLASS_NAME;
}

void ASTTypeWriter::VisitObjCInterfaceType(const ObjCInterfaceType *T) {
  Writer.AddDeclRef(T->getDecl()->getCanonicalDecl(), Record);
  Code = TYPE_OBJC_INTERFACE;
}

void ASTTypeWriter::VisitObjCObjectType(const ObjCObjectType *T) {
  Writer.AddTypeRef(T->getBaseType(), Record);
  Record.push_back(T->getNumProtocols());
  for (const auto *I : T->quals())
    Writer.AddDeclRef(I, Record);
  Code = TYPE_OBJC_OBJECT;
}

void
ASTTypeWriter::VisitObjCObjectPointerType(const ObjCObjectPointerType *T) {
  Writer.AddTypeRef(T->getPointeeType(), Record);
  Code = TYPE_OBJC_OBJECT_POINTER;
}

void
ASTTypeWriter::VisitAtomicType(const AtomicType *T) {
  Writer.AddTypeRef(T->getValueType(), Record);
  Code = TYPE_ATOMIC;
}

namespace {

class TypeLocWriter : public TypeLocVisitor<TypeLocWriter> {
  ASTWriter &Writer;
  ASTWriter::RecordDataImpl &Record;

public:
  TypeLocWriter(ASTWriter &Writer, ASTWriter::RecordDataImpl &Record)
    : Writer(Writer), Record(Record) { }

#define ABSTRACT_TYPELOC(CLASS, PARENT)
#define TYPELOC(CLASS, PARENT) \
    void Visit##CLASS##TypeLoc(CLASS##TypeLoc TyLoc);
#include "clang/AST/TypeLocNodes.def"

  void VisitArrayTypeLoc(ArrayTypeLoc TyLoc);
  void VisitFunctionTypeLoc(FunctionTypeLoc TyLoc);
};

}

void TypeLocWriter::VisitQualifiedTypeLoc(QualifiedTypeLoc TL) {
  // nothing to do
}
void TypeLocWriter::VisitBuiltinTypeLoc(BuiltinTypeLoc TL) {
  Writer.AddSourceLocation(TL.getBuiltinLoc(), Record);
  if (TL.needsExtraLocalData()) {
    Record.push_back(TL.getWrittenTypeSpec());
    Record.push_back(TL.getWrittenSignSpec());
    Record.push_back(TL.getWrittenWidthSpec());
    Record.push_back(TL.hasModeAttr());
  }
}
void TypeLocWriter::VisitComplexTypeLoc(ComplexTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitPointerTypeLoc(PointerTypeLoc TL) {
  Writer.AddSourceLocation(TL.getStarLoc(), Record);
}
void TypeLocWriter::VisitDecayedTypeLoc(DecayedTypeLoc TL) {
  // nothing to do
}
void TypeLocWriter::VisitAdjustedTypeLoc(AdjustedTypeLoc TL) {
  // nothing to do
}
void TypeLocWriter::VisitBlockPointerTypeLoc(BlockPointerTypeLoc TL) {
  Writer.AddSourceLocation(TL.getCaretLoc(), Record);
}
void TypeLocWriter::VisitLValueReferenceTypeLoc(LValueReferenceTypeLoc TL) {
  Writer.AddSourceLocation(TL.getAmpLoc(), Record);
}
void TypeLocWriter::VisitRValueReferenceTypeLoc(RValueReferenceTypeLoc TL) {
  Writer.AddSourceLocation(TL.getAmpAmpLoc(), Record);
}
void TypeLocWriter::VisitMemberPointerTypeLoc(MemberPointerTypeLoc TL) {
  Writer.AddSourceLocation(TL.getStarLoc(), Record);
  Writer.AddTypeSourceInfo(TL.getClassTInfo(), Record);
}
void TypeLocWriter::VisitArrayTypeLoc(ArrayTypeLoc TL) {
  Writer.AddSourceLocation(TL.getLBracketLoc(), Record);
  Writer.AddSourceLocation(TL.getRBracketLoc(), Record);
  Record.push_back(TL.getSizeExpr() ? 1 : 0);
  if (TL.getSizeExpr())
    Writer.AddStmt(TL.getSizeExpr());
}
void TypeLocWriter::VisitConstantArrayTypeLoc(ConstantArrayTypeLoc TL) {
  VisitArrayTypeLoc(TL);
}
void TypeLocWriter::VisitIncompleteArrayTypeLoc(IncompleteArrayTypeLoc TL) {
  VisitArrayTypeLoc(TL);
}
void TypeLocWriter::VisitVariableArrayTypeLoc(VariableArrayTypeLoc TL) {
  VisitArrayTypeLoc(TL);
}
void TypeLocWriter::VisitDependentSizedArrayTypeLoc(
                                            DependentSizedArrayTypeLoc TL) {
  VisitArrayTypeLoc(TL);
}
void TypeLocWriter::VisitDependentSizedExtVectorTypeLoc(
                                        DependentSizedExtVectorTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitVectorTypeLoc(VectorTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitExtVectorTypeLoc(ExtVectorTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitFunctionTypeLoc(FunctionTypeLoc TL) {
  Writer.AddSourceLocation(TL.getLocalRangeBegin(), Record);
  Writer.AddSourceLocation(TL.getLParenLoc(), Record);
  Writer.AddSourceLocation(TL.getRParenLoc(), Record);
  Writer.AddSourceLocation(TL.getLocalRangeEnd(), Record);
  for (unsigned i = 0, e = TL.getNumParams(); i != e; ++i)
    Writer.AddDeclRef(TL.getParam(i), Record);
}
void TypeLocWriter::VisitFunctionProtoTypeLoc(FunctionProtoTypeLoc TL) {
  VisitFunctionTypeLoc(TL);
}
void TypeLocWriter::VisitFunctionNoProtoTypeLoc(FunctionNoProtoTypeLoc TL) {
  VisitFunctionTypeLoc(TL);
}
void TypeLocWriter::VisitUnresolvedUsingTypeLoc(UnresolvedUsingTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitTypedefTypeLoc(TypedefTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitTypeOfExprTypeLoc(TypeOfExprTypeLoc TL) {
  Writer.AddSourceLocation(TL.getTypeofLoc(), Record);
  Writer.AddSourceLocation(TL.getLParenLoc(), Record);
  Writer.AddSourceLocation(TL.getRParenLoc(), Record);
}
void TypeLocWriter::VisitTypeOfTypeLoc(TypeOfTypeLoc TL) {
  Writer.AddSourceLocation(TL.getTypeofLoc(), Record);
  Writer.AddSourceLocation(TL.getLParenLoc(), Record);
  Writer.AddSourceLocation(TL.getRParenLoc(), Record);
  Writer.AddTypeSourceInfo(TL.getUnderlyingTInfo(), Record);
}
void TypeLocWriter::VisitDecltypeTypeLoc(DecltypeTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitUnaryTransformTypeLoc(UnaryTransformTypeLoc TL) {
  Writer.AddSourceLocation(TL.getKWLoc(), Record);
  Writer.AddSourceLocation(TL.getLParenLoc(), Record);
  Writer.AddSourceLocation(TL.getRParenLoc(), Record);
  Writer.AddTypeSourceInfo(TL.getUnderlyingTInfo(), Record);
}
void TypeLocWriter::VisitAutoTypeLoc(AutoTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitRecordTypeLoc(RecordTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitEnumTypeLoc(EnumTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitAttributedTypeLoc(AttributedTypeLoc TL) {
  Writer.AddSourceLocation(TL.getAttrNameLoc(), Record);
  if (TL.hasAttrOperand()) {
    SourceRange range = TL.getAttrOperandParensRange();
    Writer.AddSourceLocation(range.getBegin(), Record);
    Writer.AddSourceLocation(range.getEnd(), Record);
  }
  if (TL.hasAttrExprOperand()) {
    Expr *operand = TL.getAttrExprOperand();
    Record.push_back(operand ? 1 : 0);
    if (operand) Writer.AddStmt(operand);
  } else if (TL.hasAttrEnumOperand()) {
    Writer.AddSourceLocation(TL.getAttrEnumOperandLoc(), Record);
  }
}
void TypeLocWriter::VisitTemplateTypeParmTypeLoc(TemplateTypeParmTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitSubstTemplateTypeParmTypeLoc(
                                            SubstTemplateTypeParmTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitSubstTemplateTypeParmPackTypeLoc(
                                          SubstTemplateTypeParmPackTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitTemplateSpecializationTypeLoc(
                                           TemplateSpecializationTypeLoc TL) {
  Writer.AddSourceLocation(TL.getTemplateKeywordLoc(), Record);
  Writer.AddSourceLocation(TL.getTemplateNameLoc(), Record);
  Writer.AddSourceLocation(TL.getLAngleLoc(), Record);
  Writer.AddSourceLocation(TL.getRAngleLoc(), Record);
  for (unsigned i = 0, e = TL.getNumArgs(); i != e; ++i)
    Writer.AddTemplateArgumentLocInfo(TL.getArgLoc(i).getArgument().getKind(),
                                      TL.getArgLoc(i).getLocInfo(), Record);
}
void TypeLocWriter::VisitParenTypeLoc(ParenTypeLoc TL) {
  Writer.AddSourceLocation(TL.getLParenLoc(), Record);
  Writer.AddSourceLocation(TL.getRParenLoc(), Record);
}
void TypeLocWriter::VisitElaboratedTypeLoc(ElaboratedTypeLoc TL) {
  Writer.AddSourceLocation(TL.getElaboratedKeywordLoc(), Record);
  Writer.AddNestedNameSpecifierLoc(TL.getQualifierLoc(), Record);
}
void TypeLocWriter::VisitInjectedClassNameTypeLoc(InjectedClassNameTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitDependentNameTypeLoc(DependentNameTypeLoc TL) {
  Writer.AddSourceLocation(TL.getElaboratedKeywordLoc(), Record);
  Writer.AddNestedNameSpecifierLoc(TL.getQualifierLoc(), Record);
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitDependentTemplateSpecializationTypeLoc(
       DependentTemplateSpecializationTypeLoc TL) {
  Writer.AddSourceLocation(TL.getElaboratedKeywordLoc(), Record);
  Writer.AddNestedNameSpecifierLoc(TL.getQualifierLoc(), Record);
  Writer.AddSourceLocation(TL.getTemplateKeywordLoc(), Record);
  Writer.AddSourceLocation(TL.getTemplateNameLoc(), Record);
  Writer.AddSourceLocation(TL.getLAngleLoc(), Record);
  Writer.AddSourceLocation(TL.getRAngleLoc(), Record);
  for (unsigned I = 0, E = TL.getNumArgs(); I != E; ++I)
    Writer.AddTemplateArgumentLocInfo(TL.getArgLoc(I).getArgument().getKind(),
                                      TL.getArgLoc(I).getLocInfo(), Record);
}
void TypeLocWriter::VisitPackExpansionTypeLoc(PackExpansionTypeLoc TL) {
  Writer.AddSourceLocation(TL.getEllipsisLoc(), Record);
}
void TypeLocWriter::VisitObjCInterfaceTypeLoc(ObjCInterfaceTypeLoc TL) {
  Writer.AddSourceLocation(TL.getNameLoc(), Record);
}
void TypeLocWriter::VisitObjCObjectTypeLoc(ObjCObjectTypeLoc TL) {
  Record.push_back(TL.hasBaseTypeAsWritten());
  Writer.AddSourceLocation(TL.getLAngleLoc(), Record);
  Writer.AddSourceLocation(TL.getRAngleLoc(), Record);
  for (unsigned i = 0, e = TL.getNumProtocols(); i != e; ++i)
    Writer.AddSourceLocation(TL.getProtocolLoc(i), Record);
}
void TypeLocWriter::VisitObjCObjectPointerTypeLoc(ObjCObjectPointerTypeLoc TL) {
  Writer.AddSourceLocation(TL.getStarLoc(), Record);
}
void TypeLocWriter::VisitAtomicTypeLoc(AtomicTypeLoc TL) {
  Writer.AddSourceLocation(TL.getKWLoc(), Record);
  Writer.AddSourceLocation(TL.getLParenLoc(), Record);
  Writer.AddSourceLocation(TL.getRParenLoc(), Record);
}

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

static void EmitBlockID(unsigned ID, const char *Name,
                        llvm::BitstreamWriter &Stream,
                        ASTWriter::RecordDataImpl &Record) {
  Record.clear();
  Record.push_back(ID);
  Stream.EmitRecord(llvm::bitc::BLOCKINFO_CODE_SETBID, Record);

  // Emit the block name if present.
  if (Name == 0 || Name[0] == 0) return;
  Record.clear();
  while (*Name)
    Record.push_back(*Name++);
  Stream.EmitRecord(llvm::bitc::BLOCKINFO_CODE_BLOCKNAME, Record);
}

static void EmitRecordID(unsigned ID, const char *Name,
                         llvm::BitstreamWriter &Stream,
                         ASTWriter::RecordDataImpl &Record) {
  Record.clear();
  Record.push_back(ID);
  while (*Name)
    Record.push_back(*Name++);
  Stream.EmitRecord(llvm::bitc::BLOCKINFO_CODE_SETRECORDNAME, Record);
}

static void AddStmtsExprs(llvm::BitstreamWriter &Stream,
                          ASTWriter::RecordDataImpl &Record) {
#define RECORD(X) EmitRecordID(X, #X, Stream, Record)
  RECORD(STMT_STOP);
  RECORD(STMT_NULL_PTR);
  RECORD(STMT_NULL);
  RECORD(STMT_COMPOUND);
  RECORD(STMT_CASE);
  RECORD(STMT_DEFAULT);
  RECORD(STMT_LABEL);
  RECORD(STMT_ATTRIBUTED);
  RECORD(STMT_IF);
  RECORD(STMT_SWITCH);
  RECORD(STMT_WHILE);
  RECORD(STMT_DO);
  RECORD(STMT_FOR);
  RECORD(STMT_GOTO);
  RECORD(STMT_INDIRECT_GOTO);
  RECORD(STMT_CONTINUE);
  RECORD(STMT_BREAK);
  RECORD(STMT_RETURN);
  RECORD(STMT_DECL);
  RECORD(STMT_GCCASM);
  RECORD(STMT_MSASM);
  RECORD(EXPR_PREDEFINED);
  RECORD(EXPR_DECL_REF);
  RECORD(EXPR_INTEGER_LITERAL);
  RECORD(EXPR_FLOATING_LITERAL);
  RECORD(EXPR_IMAGINARY_LITERAL);
  RECORD(EXPR_STRING_LITERAL);
  RECORD(EXPR_CHARACTER_LITERAL);
  RECORD(EXPR_PAREN);
  RECORD(EXPR_UNARY_OPERATOR);
  RECORD(EXPR_SIZEOF_ALIGN_OF);
  RECORD(EXPR_ARRAY_SUBSCRIPT);
  RECORD(EXPR_CALL);
  RECORD(EXPR_MEMBER);
  RECORD(EXPR_BINARY_OPERATOR);
  RECORD(EXPR_COMPOUND_ASSIGN_OPERATOR);
  RECORD(EXPR_CONDITIONAL_OPERATOR);
  RECORD(EXPR_IMPLICIT_CAST);
  RECORD(EXPR_CSTYLE_CAST);
  RECORD(EXPR_COMPOUND_LITERAL);
  RECORD(EXPR_EXT_VECTOR_ELEMENT);
  RECORD(EXPR_INIT_LIST);
  RECORD(EXPR_DESIGNATED_INIT);
  RECORD(EXPR_IMPLICIT_VALUE_INIT);
  RECORD(EXPR_VA_ARG);
  RECORD(EXPR_ADDR_LABEL);
  RECORD(EXPR_STMT);
  RECORD(EXPR_CHOOSE);
  RECORD(EXPR_GNU_NULL);
  RECORD(EXPR_SHUFFLE_VECTOR);
  RECORD(EXPR_BLOCK);
  RECORD(EXPR_GENERIC_SELECTION);
  RECORD(EXPR_OBJC_STRING_LITERAL);
  RECORD(EXPR_OBJC_BOXED_EXPRESSION);
  RECORD(EXPR_OBJC_ARRAY_LITERAL);
  RECORD(EXPR_OBJC_DICTIONARY_LITERAL);
  RECORD(EXPR_OBJC_ENCODE);
  RECORD(EXPR_OBJC_SELECTOR_EXPR);
  RECORD(EXPR_OBJC_PROTOCOL_EXPR);
  RECORD(EXPR_OBJC_IVAR_REF_EXPR);
  RECORD(EXPR_OBJC_PROPERTY_REF_EXPR);
  RECORD(EXPR_OBJC_KVC_REF_EXPR);
  RECORD(EXPR_OBJC_MESSAGE_EXPR);
  RECORD(STMT_OBJC_FOR_COLLECTION);
  RECORD(STMT_OBJC_CATCH);
  RECORD(STMT_OBJC_FINALLY);
  RECORD(STMT_OBJC_AT_TRY);
  RECORD(STMT_OBJC_AT_SYNCHRONIZED);
  RECORD(STMT_OBJC_AT_THROW);
  RECORD(EXPR_OBJC_BOOL_LITERAL);
  RECORD(EXPR_CXX_OPERATOR_CALL);
  RECORD(EXPR_CXX_CONSTRUCT);
  RECORD(EXPR_CXX_STATIC_CAST);
  RECORD(EXPR_CXX_DYNAMIC_CAST);
  RECORD(EXPR_CXX_REINTERPRET_CAST);
  RECORD(EXPR_CXX_CONST_CAST);
  RECORD(EXPR_CXX_FUNCTIONAL_CAST);
  RECORD(EXPR_USER_DEFINED_LITERAL);
  RECORD(EXPR_CXX_STD_INITIALIZER_LIST);
  RECORD(EXPR_CXX_BOOL_LITERAL);
  RECORD(EXPR_CXX_NULL_PTR_LITERAL);
  RECORD(EXPR_CXX_TYPEID_EXPR);
  RECORD(EXPR_CXX_TYPEID_TYPE);
  RECORD(EXPR_CXX_UUIDOF_EXPR);
  RECORD(EXPR_CXX_UUIDOF_TYPE);
  RECORD(EXPR_CXX_THIS);
  RECORD(EXPR_CXX_THROW);
  RECORD(EXPR_CXX_DEFAULT_ARG);
  RECORD(EXPR_CXX_BIND_TEMPORARY);
  RECORD(EXPR_CXX_SCALAR_VALUE_INIT);
  RECORD(EXPR_CXX_NEW);
  RECORD(EXPR_CXX_DELETE);
  RECORD(EXPR_CXX_PSEUDO_DESTRUCTOR);
  RECORD(EXPR_EXPR_WITH_CLEANUPS);
  RECORD(EXPR_CXX_DEPENDENT_SCOPE_MEMBER);
  RECORD(EXPR_CXX_DEPENDENT_SCOPE_DECL_REF);
  RECORD(EXPR_CXX_UNRESOLVED_CONSTRUCT);
  RECORD(EXPR_CXX_UNRESOLVED_MEMBER);
  RECORD(EXPR_CXX_UNRESOLVED_LOOKUP);
  RECORD(EXPR_CXX_NOEXCEPT);
  RECORD(EXPR_OPAQUE_VALUE);
  RECORD(EXPR_PACK_EXPANSION);
  RECORD(EXPR_SIZEOF_PACK);
  RECORD(EXPR_SUBST_NON_TYPE_TEMPLATE_PARM_PACK);
  RECORD(EXPR_CUDA_KERNEL_CALL);
#undef RECORD
}

void ASTWriter::WriteBlockInfoBlock() {
  RecordData Record;
  Stream.EnterSubblock(llvm::bitc::BLOCKINFO_BLOCK_ID, 3);

#define BLOCK(X) EmitBlockID(X ## _ID, #X, Stream, Record)
#define RECORD(X) EmitRecordID(X, #X, Stream, Record)

  // Control Block.
  BLOCK(CONTROL_BLOCK);
  RECORD(METADATA);
  RECORD(MODULE_NAME);
  RECORD(MODULE_MAP_FILE);
  RECORD(IMPORTS);
  RECORD(LANGUAGE_OPTIONS);
  RECORD(TARGET_OPTIONS);
  RECORD(ORIGINAL_FILE);
  RECORD(ORIGINAL_PCH_DIR);
  RECORD(ORIGINAL_FILE_ID);
  RECORD(INPUT_FILE_OFFSETS);
  RECORD(DIAGNOSTIC_OPTIONS);
  RECORD(FILE_SYSTEM_OPTIONS);
  RECORD(HEADER_SEARCH_OPTIONS);
  RECORD(PREPROCESSOR_OPTIONS);

  BLOCK(INPUT_FILES_BLOCK);
  RECORD(INPUT_FILE);

  // AST Top-Level Block.
  BLOCK(AST_BLOCK);
  RECORD(TYPE_OFFSET);
  RECORD(DECL_OFFSET);
  RECORD(IDENTIFIER_OFFSET);
  RECORD(IDENTIFIER_TABLE);
  RECORD(EAGERLY_DESERIALIZED_DECLS);
  RECORD(SPECIAL_TYPES);
  RECORD(STATISTICS);
  RECORD(TENTATIVE_DEFINITIONS);
  RECORD(UNUSED_FILESCOPED_DECLS);
  RECORD(LOCALLY_SCOPED_EXTERN_C_DECLS);
  RECORD(SELECTOR_OFFSETS);
  RECORD(METHOD_POOL);
  RECORD(PP_COUNTER_VALUE);
  RECORD(SOURCE_LOCATION_OFFSETS);
  RECORD(SOURCE_LOCATION_PRELOADS);
  RECORD(EXT_VECTOR_DECLS);
  RECORD(PPD_ENTITIES_OFFSETS);
  RECORD(REFERENCED_SELECTOR_POOL);
  RECORD(TU_UPDATE_LEXICAL);
  RECORD(LOCAL_REDECLARATIONS_MAP);
  RECORD(SEMA_DECL_REFS);
  RECORD(WEAK_UNDECLARED_IDENTIFIERS);
  RECORD(PENDING_IMPLICIT_INSTANTIATIONS);
  RECORD(DECL_REPLACEMENTS);
  RECORD(UPDATE_VISIBLE);
  RECORD(DECL_UPDATE_OFFSETS);
  RECORD(DECL_UPDATES);
  RECORD(CXX_BASE_SPECIFIER_OFFSETS);
  RECORD(DIAG_PRAGMA_MAPPINGS);
  RECORD(CUDA_SPECIAL_DECL_REFS);
  RECORD(HEADER_SEARCH_TABLE);
  RECORD(FP_PRAGMA_OPTIONS);
  RECORD(OPENCL_EXTENSIONS);
  RECORD(DELEGATING_CTORS);
  RECORD(KNOWN_NAMESPACES);
  RECORD(UNDEFINED_BUT_USED);
  RECORD(MODULE_OFFSET_MAP);
  RECORD(SOURCE_MANAGER_LINE_TABLE);
  RECORD(OBJC_CATEGORIES_MAP);
  RECORD(FILE_SORTED_DECLS);
  RECORD(IMPORTED_MODULES);
  RECORD(MERGED_DECLARATIONS);
  RECORD(LOCAL_REDECLARATIONS);
  RECORD(OBJC_CATEGORIES);
  RECORD(MACRO_OFFSET);
  RECORD(MACRO_TABLE);
  RECORD(LATE_PARSED_TEMPLATE);

  // SourceManager Block.
  BLOCK(SOURCE_MANAGER_BLOCK);
  RECORD(SM_SLOC_FILE_ENTRY);
  RECORD(SM_SLOC_BUFFER_ENTRY);
  RECORD(SM_SLOC_BUFFER_BLOB);
  RECORD(SM_SLOC_EXPANSION_ENTRY);

  // Preprocessor Block.
  BLOCK(PREPROCESSOR_BLOCK);
  RECORD(PP_MACRO_OBJECT_LIKE);
  RECORD(PP_MACRO_FUNCTION_LIKE);
  RECORD(PP_TOKEN);
  
  // Decls and Types block.
  BLOCK(DECLTYPES_BLOCK);
  RECORD(TYPE_EXT_QUAL);
  RECORD(TYPE_COMPLEX);
  RECORD(TYPE_POINTER);
  RECORD(TYPE_BLOCK_POINTER);
  RECORD(TYPE_LVALUE_REFERENCE);
  RECORD(TYPE_RVALUE_REFERENCE);
  RECORD(TYPE_MEMBER_POINTER);
  RECORD(TYPE_CONSTANT_ARRAY);
  RECORD(TYPE_INCOMPLETE_ARRAY);
  RECORD(TYPE_VARIABLE_ARRAY);
  RECORD(TYPE_VECTOR);
  RECORD(TYPE_EXT_VECTOR);
  RECORD(TYPE_FUNCTION_PROTO);
  RECORD(TYPE_FUNCTION_NO_PROTO);
  RECORD(TYPE_TYPEDEF);
  RECORD(TYPE_TYPEOF_EXPR);
  RECORD(TYPE_TYPEOF);
  RECORD(TYPE_RECORD);
  RECORD(TYPE_ENUM);
  RECORD(TYPE_OBJC_INTERFACE);
  RECORD(TYPE_OBJC_OBJECT);
  RECORD(TYPE_OBJC_OBJECT_POINTER);
  RECORD(TYPE_DECLTYPE);
  RECORD(TYPE_ELABORATED);
  RECORD(TYPE_SUBST_TEMPLATE_TYPE_PARM);
  RECORD(TYPE_UNRESOLVED_USING);
  RECORD(TYPE_INJECTED_CLASS_NAME);
  RECORD(TYPE_OBJC_OBJECT);
  RECORD(TYPE_TEMPLATE_TYPE_PARM);
  RECORD(TYPE_TEMPLATE_SPECIALIZATION);
  RECORD(TYPE_DEPENDENT_NAME);
  RECORD(TYPE_DEPENDENT_TEMPLATE_SPECIALIZATION);
  RECORD(TYPE_DEPENDENT_SIZED_ARRAY);
  RECORD(TYPE_PAREN);
  RECORD(TYPE_PACK_EXPANSION);
  RECORD(TYPE_ATTRIBUTED);
  RECORD(TYPE_SUBST_TEMPLATE_TYPE_PARM_PACK);
  RECORD(TYPE_ATOMIC);
  RECORD(DECL_TYPEDEF);
  RECORD(DECL_ENUM);
  RECORD(DECL_RECORD);
  RECORD(DECL_ENUM_CONSTANT);
  RECORD(DECL_FUNCTION);
  RECORD(DECL_OBJC_METHOD);
  RECORD(DECL_OBJC_INTERFACE);
  RECORD(DECL_OBJC_PROTOCOL);
  RECORD(DECL_OBJC_IVAR);
  RECORD(DECL_OBJC_AT_DEFS_FIELD);
  RECORD(DECL_OBJC_CATEGORY);
  RECORD(DECL_OBJC_CATEGORY_IMPL);
  RECORD(DECL_OBJC_IMPLEMENTATION);
  RECORD(DECL_OBJC_COMPATIBLE_ALIAS);
  RECORD(DECL_OBJC_PROPERTY);
  RECORD(DECL_OBJC_PROPERTY_IMPL);
  RECORD(DECL_FIELD);
  RECORD(DECL_MS_PROPERTY);
  RECORD(DECL_VAR);
  RECORD(DECL_IMPLICIT_PARAM);
  RECORD(DECL_PARM_VAR);
  RECORD(DECL_FILE_SCOPE_ASM);
  RECORD(DECL_BLOCK);
  RECORD(DECL_CONTEXT_LEXICAL);
  RECORD(DECL_CONTEXT_VISIBLE);
  RECORD(DECL_NAMESPACE);
  RECORD(DECL_NAMESPACE_ALIAS);
  RECORD(DECL_USING);
  RECORD(DECL_USING_SHADOW);
  RECORD(DECL_USING_DIRECTIVE);
  RECORD(DECL_UNRESOLVED_USING_VALUE);
  RECORD(DECL_UNRESOLVED_USING_TYPENAME);
  RECORD(DECL_LINKAGE_SPEC);
  RECORD(DECL_CXX_RECORD);
  RECORD(DECL_CXX_METHOD);
  RECORD(DECL_CXX_CONSTRUCTOR);
  RECORD(DECL_CXX_DESTRUCTOR);
  RECORD(DECL_CXX_CONVERSION);
  RECORD(DECL_ACCESS_SPEC);
  RECORD(DECL_FRIEND);
  RECORD(DECL_FRIEND_TEMPLATE);
  RECORD(DECL_CLASS_TEMPLATE);
  RECORD(DECL_CLASS_TEMPLATE_SPECIALIZATION);
  RECORD(DECL_CLASS_TEMPLATE_PARTIAL_SPECIALIZATION);
  RECORD(DECL_VAR_TEMPLATE);
  RECORD(DECL_VAR_TEMPLATE_SPECIALIZATION);
  RECORD(DECL_VAR_TEMPLATE_PARTIAL_SPECIALIZATION);
  RECORD(DECL_FUNCTION_TEMPLATE);
  RECORD(DECL_TEMPLATE_TYPE_PARM);
  RECORD(DECL_NON_TYPE_TEMPLATE_PARM);
  RECORD(DECL_TEMPLATE_TEMPLATE_PARM);
  RECORD(DECL_STATIC_ASSERT);
  RECORD(DECL_CXX_BASE_SPECIFIERS);
  RECORD(DECL_INDIRECTFIELD);
  RECORD(DECL_EXPANDED_NON_TYPE_TEMPLATE_PARM_PACK);
  
  // Statements and Exprs can occur in the Decls and Types block.
  AddStmtsExprs(Stream, Record);

  BLOCK(PREPROCESSOR_DETAIL_BLOCK);
  RECORD(PPD_MACRO_EXPANSION);
  RECORD(PPD_MACRO_DEFINITION);
  RECORD(PPD_INCLUSION_DIRECTIVE);
  
#undef RECORD
#undef BLOCK
  Stream.ExitBlock();
}

/// \brief Adjusts the given filename to only write out the portion of the
/// filename that is not part of the system root directory.
///
/// \param Filename the file name to adjust.
///
/// \param isysroot When non-NULL, the PCH file is a relocatable PCH file and
/// the returned filename will be adjusted by this system root.
///
/// \returns either the original filename (if it needs no adjustment) or the
/// adjusted filename (which points into the @p Filename parameter).
static const char *
adjustFilenameForRelocatablePCH(const char *Filename, StringRef isysroot) {
  assert(Filename && "No file name to adjust?");

  if (isysroot.empty())
    return Filename;

  // Verify that the filename and the system root have the same prefix.
  unsigned Pos = 0;
  for (; Filename[Pos] && Pos < isysroot.size(); ++Pos)
    if (Filename[Pos] != isysroot[Pos])
      return Filename; // Prefixes don't match.

  // We hit the end of the filename before we hit the end of the system root.
  if (!Filename[Pos])
    return Filename;

  // If the file name has a '/' at the current position, skip over the '/'.
  // We distinguish sysroot-based includes from absolute includes by the
  // absence of '/' at the beginning of sysroot-based includes.
  if (Filename[Pos] == '/')
    ++Pos;

  return Filename + Pos;
}

/// \brief Write the control block.
void ASTWriter::WriteControlBlock(Preprocessor &PP, ASTContext &Context,
                                  StringRef isysroot,
                                  const std::string &OutputFile) {
  using namespace llvm;
  Stream.EnterSubblock(CONTROL_BLOCK_ID, 5);
  RecordData Record;
  
  // Metadata
  BitCodeAbbrev *MetadataAbbrev = new BitCodeAbbrev();
  MetadataAbbrev->Add(BitCodeAbbrevOp(METADATA));
  MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // Major
  MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // Minor
  MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // Clang maj.
  MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // Clang min.
  MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Relocatable
  MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Errors
  MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // SVN branch/tag
  unsigned MetadataAbbrevCode = Stream.EmitAbbrev(MetadataAbbrev);
  Record.push_back(METADATA);
  Record.push_back(VERSION_MAJOR);
  Record.push_back(VERSION_MINOR);
  Record.push_back(CLANG_VERSION_MAJOR);
  Record.push_back(CLANG_VERSION_MINOR);
  Record.push_back(!isysroot.empty());
  Record.push_back(ASTHasCompilerErrors);
  Stream.EmitRecordWithBlob(MetadataAbbrevCode, Record,
                            getClangFullRepositoryVersion());

  // Module name
  if (WritingModule) {
    BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
    Abbrev->Add(BitCodeAbbrevOp(MODULE_NAME));
    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Name
    unsigned AbbrevCode = Stream.EmitAbbrev(Abbrev);
    RecordData Record;
    Record.push_back(MODULE_NAME);
    Stream.EmitRecordWithBlob(AbbrevCode, Record, WritingModule->Name);
  }

  // Module map file
  if (WritingModule) {
    BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
    Abbrev->Add(BitCodeAbbrevOp(MODULE_MAP_FILE));
    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Filename
    unsigned AbbrevCode = Stream.EmitAbbrev(Abbrev);

    assert(WritingModule->ModuleMap && "missing module map");
    SmallString<128> ModuleMap(WritingModule->ModuleMap->getName());
    llvm::sys::fs::make_absolute(ModuleMap);
    RecordData Record;
    Record.push_back(MODULE_MAP_FILE);
    Stream.EmitRecordWithBlob(AbbrevCode, Record, ModuleMap.str());
  }

  // Imports
  if (Chain) {
    serialization::ModuleManager &Mgr = Chain->getModuleManager();
    Record.clear();

    for (ModuleManager::ModuleIterator M = Mgr.begin(), MEnd = Mgr.end();
         M != MEnd; ++M) {
      // Skip modules that weren't directly imported.
      if (!(*M)->isDirectlyImported())
        continue;

      Record.push_back((unsigned)(*M)->Kind); // FIXME: Stable encoding
      AddSourceLocation((*M)->ImportLoc, Record);
      Record.push_back((*M)->File->getSize());
      Record.push_back((*M)->File->getModificationTime());
      const std::string &FileName = (*M)->FileName;
      Record.push_back(FileName.size());
      Record.append(FileName.begin(), FileName.end());
    }
    Stream.EmitRecord(IMPORTS, Record);
  }

  // Language options.
  Record.clear();
  const LangOptions &LangOpts = Context.getLangOpts();
#define LANGOPT(Name, Bits, Default, Description) \
  Record.push_back(LangOpts.Name);
#define ENUM_LANGOPT(Name, Type, Bits, Default, Description) \
  Record.push_back(static_cast<unsigned>(LangOpts.get##Name()));
#include "clang/Basic/LangOptions.def"  
#define SANITIZER(NAME, ID) Record.push_back(LangOpts.Sanitize.ID);
#include "clang/Basic/Sanitizers.def"

  Record.push_back((unsigned) LangOpts.ObjCRuntime.getKind());
  AddVersionTuple(LangOpts.ObjCRuntime.getVersion(), Record);
  
  Record.push_back(LangOpts.CurrentModule.size());
  Record.append(LangOpts.CurrentModule.begin(), LangOpts.CurrentModule.end());

  // Comment options.
  Record.push_back(LangOpts.CommentOpts.BlockCommandNames.size());
  for (CommentOptions::BlockCommandNamesTy::const_iterator
           I = LangOpts.CommentOpts.BlockCommandNames.begin(),
           IEnd = LangOpts.CommentOpts.BlockCommandNames.end();
       I != IEnd; ++I) {
    AddString(*I, Record);
  }
  Record.push_back(LangOpts.CommentOpts.ParseAllComments);

  Stream.EmitRecord(LANGUAGE_OPTIONS, Record);

  // Target options.
  Record.clear();
  const TargetInfo &Target = Context.getTargetInfo();
  const TargetOptions &TargetOpts = Target.getTargetOpts();
  AddString(TargetOpts.Triple, Record);
  AddString(TargetOpts.CPU, Record);
  AddString(TargetOpts.ABI, Record);
  AddString(TargetOpts.LinkerVersion, Record);
  Record.push_back(TargetOpts.FeaturesAsWritten.size());
  for (unsigned I = 0, N = TargetOpts.FeaturesAsWritten.size(); I != N; ++I) {
    AddString(TargetOpts.FeaturesAsWritten[I], Record);
  }
  Record.push_back(TargetOpts.Features.size());
  for (unsigned I = 0, N = TargetOpts.Features.size(); I != N; ++I) {
    AddString(TargetOpts.Features[I], Record);
  }
  Stream.EmitRecord(TARGET_OPTIONS, Record);

  // Diagnostic options.
  Record.clear();
  const DiagnosticOptions &DiagOpts
    = Context.getDiagnostics().getDiagnosticOptions();
#define DIAGOPT(Name, Bits, Default) Record.push_back(DiagOpts.Name);
#define ENUM_DIAGOPT(Name, Type, Bits, Default) \
  Record.push_back(static_cast<unsigned>(DiagOpts.get##Name()));
#include "clang/Basic/DiagnosticOptions.def"
  Record.push_back(DiagOpts.Warnings.size());
  for (unsigned I = 0, N = DiagOpts.Warnings.size(); I != N; ++I)
    AddString(DiagOpts.Warnings[I], Record);
  // Note: we don't serialize the log or serialization file names, because they
  // are generally transient files and will almost always be overridden.
  Stream.EmitRecord(DIAGNOSTIC_OPTIONS, Record);

  // File system options.
  Record.clear();
  const FileSystemOptions &FSOpts
    = Context.getSourceManager().getFileManager().getFileSystemOptions();
  AddString(FSOpts.WorkingDir, Record);
  Stream.EmitRecord(FILE_SYSTEM_OPTIONS, Record);

  // Header search options.
  Record.clear();
  const HeaderSearchOptions &HSOpts
    = PP.getHeaderSearchInfo().getHeaderSearchOpts();
  AddString(HSOpts.Sysroot, Record);

  // Include entries.
  Record.push_back(HSOpts.UserEntries.size());
  for (unsigned I = 0, N = HSOpts.UserEntries.size(); I != N; ++I) {
    const HeaderSearchOptions::Entry &Entry = HSOpts.UserEntries[I];
    AddString(Entry.Path, Record);
    Record.push_back(static_cast<unsigned>(Entry.Group));
    Record.push_back(Entry.IsFramework);
    Record.push_back(Entry.IgnoreSysRoot);
  }

  // System header prefixes.
  Record.push_back(HSOpts.SystemHeaderPrefixes.size());
  for (unsigned I = 0, N = HSOpts.SystemHeaderPrefixes.size(); I != N; ++I) {
    AddString(HSOpts.SystemHeaderPrefixes[I].Prefix, Record);
    Record.push_back(HSOpts.SystemHeaderPrefixes[I].IsSystemHeader);
  }

  AddString(HSOpts.ResourceDir, Record);
  AddString(HSOpts.ModuleCachePath, Record);
  AddString(HSOpts.ModuleUserBuildPath, Record);
  Record.push_back(HSOpts.DisableModuleHash);
  Record.push_back(HSOpts.UseBuiltinIncludes);
  Record.push_back(HSOpts.UseStandardSystemIncludes);
  Record.push_back(HSOpts.UseStandardCXXIncludes);
  Record.push_back(HSOpts.UseLibcxx);
  Stream.EmitRecord(HEADER_SEARCH_OPTIONS, Record);

  // Preprocessor options.
  Record.clear();
  const PreprocessorOptions &PPOpts = PP.getPreprocessorOpts();

  // Macro definitions.
  Record.push_back(PPOpts.Macros.size());
  for (unsigned I = 0, N = PPOpts.Macros.size(); I != N; ++I) {
    AddString(PPOpts.Macros[I].first, Record);
    Record.push_back(PPOpts.Macros[I].second);
  }

  // Includes
  Record.push_back(PPOpts.Includes.size());
  for (unsigned I = 0, N = PPOpts.Includes.size(); I != N; ++I)
    AddString(PPOpts.Includes[I], Record);

  // Macro includes
  Record.push_back(PPOpts.MacroIncludes.size());
  for (unsigned I = 0, N = PPOpts.MacroIncludes.size(); I != N; ++I)
    AddString(PPOpts.MacroIncludes[I], Record);

  Record.push_back(PPOpts.UsePredefines);
  // Detailed record is important since it is used for the module cache hash.
  Record.push_back(PPOpts.DetailedRecord);
  AddString(PPOpts.ImplicitPCHInclude, Record);
  AddString(PPOpts.ImplicitPTHInclude, Record);
  Record.push_back(static_cast<unsigned>(PPOpts.ObjCXXARCStandardLibrary));
  Stream.EmitRecord(PREPROCESSOR_OPTIONS, Record);

  // Original file name and file ID
  SourceManager &SM = Context.getSourceManager();
  if (const FileEntry *MainFile = SM.getFileEntryForID(SM.getMainFileID())) {
    BitCodeAbbrev *FileAbbrev = new BitCodeAbbrev();
    FileAbbrev->Add(BitCodeAbbrevOp(ORIGINAL_FILE));
    FileAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // File ID
    FileAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // File name
    unsigned FileAbbrevCode = Stream.EmitAbbrev(FileAbbrev);

    SmallString<128> MainFilePath(MainFile->getName());

    llvm::sys::fs::make_absolute(MainFilePath);

    const char *MainFileNameStr = MainFilePath.c_str();
    MainFileNameStr = adjustFilenameForRelocatablePCH(MainFileNameStr,
                                                      isysroot);
    Record.clear();
    Record.push_back(ORIGINAL_FILE);
    Record.push_back(SM.getMainFileID().getOpaqueValue());
    Stream.EmitRecordWithBlob(FileAbbrevCode, Record, MainFileNameStr);
  }

  Record.clear();
  Record.push_back(SM.getMainFileID().getOpaqueValue());
  Stream.EmitRecord(ORIGINAL_FILE_ID, Record);

  // Original PCH directory
  if (!OutputFile.empty() && OutputFile != "-") {
    BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
    Abbrev->Add(BitCodeAbbrevOp(ORIGINAL_PCH_DIR));
    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // File name
    unsigned AbbrevCode = Stream.EmitAbbrev(Abbrev);

    SmallString<128> OutputPath(OutputFile);

    llvm::sys::fs::make_absolute(OutputPath);
    StringRef origDir = llvm::sys::path::parent_path(OutputPath);

    RecordData Record;
    Record.push_back(ORIGINAL_PCH_DIR);
    Stream.EmitRecordWithBlob(AbbrevCode, Record, origDir);
  }

  WriteInputFiles(Context.SourceMgr,
                  PP.getHeaderSearchInfo().getHeaderSearchOpts(),
                  isysroot,
                  PP.getLangOpts().Modules);
  Stream.ExitBlock();
}

namespace  {
  /// \brief An input file.
  struct InputFileEntry {
    const FileEntry *File;
    bool IsSystemFile;
    bool BufferOverridden;
  };
}

void ASTWriter::WriteInputFiles(SourceManager &SourceMgr,
                                HeaderSearchOptions &HSOpts,
                                StringRef isysroot,
                                bool Modules) {
  using namespace llvm;
  Stream.EnterSubblock(INPUT_FILES_BLOCK_ID, 4);
  RecordData Record;
  
  // Create input-file abbreviation.
  BitCodeAbbrev *IFAbbrev = new BitCodeAbbrev();
  IFAbbrev->Add(BitCodeAbbrevOp(INPUT_FILE));
  IFAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ID
  IFAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 12)); // Size
  IFAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 32)); // Modification time
  IFAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Overridden
  IFAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // File name
  unsigned IFAbbrevCode = Stream.EmitAbbrev(IFAbbrev);

  // Get all ContentCache objects for files, sorted by whether the file is a
  // system one or not. System files go at the back, users files at the front.
  std::deque<InputFileEntry> SortedFiles;
  for (unsigned I = 1, N = SourceMgr.local_sloc_entry_size(); I != N; ++I) {
    // Get this source location entry.
    const SrcMgr::SLocEntry *SLoc = &SourceMgr.getLocalSLocEntry(I);
    assert(&SourceMgr.getSLocEntry(FileID::get(I)) == SLoc);

    // We only care about file entries that were not overridden.
    if (!SLoc->isFile())
      continue;
    const SrcMgr::ContentCache *Cache = SLoc->getFile().getContentCache();
    if (!Cache->OrigEntry)
      continue;

    InputFileEntry Entry;
    Entry.File = Cache->OrigEntry;
    Entry.IsSystemFile = Cache->IsSystemFile;
    Entry.BufferOverridden = Cache->BufferOverridden;
    if (Cache->IsSystemFile)
      SortedFiles.push_back(Entry);
    else
      SortedFiles.push_front(Entry);
  }

  unsigned UserFilesNum = 0;
  // Write out all of the input files.
  std::vector<uint32_t> InputFileOffsets;
  for (std::deque<InputFileEntry>::iterator
         I = SortedFiles.begin(), E = SortedFiles.end(); I != E; ++I) {
    const InputFileEntry &Entry = *I;

    uint32_t &InputFileID = InputFileIDs[Entry.File];
    if (InputFileID != 0)
      continue; // already recorded this file.

    // Record this entry's offset.
    InputFileOffsets.push_back(Stream.GetCurrentBitNo());

    InputFileID = InputFileOffsets.size();

    if (!Entry.IsSystemFile)
      ++UserFilesNum;

    Record.clear();
    Record.push_back(INPUT_FILE);
    Record.push_back(InputFileOffsets.size());

    // Emit size/modification time for this file.
    Record.push_back(Entry.File->getSize());
    Record.push_back(Entry.File->getModificationTime());

    // Whether this file was overridden.
    Record.push_back(Entry.BufferOverridden);

    // Turn the file name into an absolute path, if it isn't already.
    const char *Filename = Entry.File->getName();
    SmallString<128> FilePath(Filename);
    
    // Ask the file manager to fixup the relative path for us. This will 
    // honor the working directory.
    SourceMgr.getFileManager().FixupRelativePath(FilePath);
    
    // FIXME: This call to make_absolute shouldn't be necessary, the
    // call to FixupRelativePath should always return an absolute path.
    llvm::sys::fs::make_absolute(FilePath);
    Filename = FilePath.c_str();
    
    Filename = adjustFilenameForRelocatablePCH(Filename, isysroot);

    Stream.EmitRecordWithBlob(IFAbbrevCode, Record, Filename);
  }  

  Stream.ExitBlock();

  // Create input file offsets abbreviation.
  BitCodeAbbrev *OffsetsAbbrev = new BitCodeAbbrev();
  OffsetsAbbrev->Add(BitCodeAbbrevOp(INPUT_FILE_OFFSETS));
  OffsetsAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # input files
  OffsetsAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # non-system
                                                                //   input files
  OffsetsAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));   // Array
  unsigned OffsetsAbbrevCode = Stream.EmitAbbrev(OffsetsAbbrev);

  // Write input file offsets.
  Record.clear();
  Record.push_back(INPUT_FILE_OFFSETS);
  Record.push_back(InputFileOffsets.size());
  Record.push_back(UserFilesNum);
  Stream.EmitRecordWithBlob(OffsetsAbbrevCode, Record, data(InputFileOffsets));
}

//===----------------------------------------------------------------------===//
// Source Manager Serialization
//===----------------------------------------------------------------------===//

/// \brief Create an abbreviation for the SLocEntry that refers to a
/// file.
static unsigned CreateSLocFileAbbrev(llvm::BitstreamWriter &Stream) {
  using namespace llvm;
  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SM_SLOC_FILE_ENTRY));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Offset
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Include location
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2)); // Characteristic
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Line directives
  // FileEntry fields.
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Input File ID
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // NumCreatedFIDs
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 24)); // FirstDeclIndex
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // NumDecls
  return Stream.EmitAbbrev(Abbrev);
}

/// \brief Create an abbreviation for the SLocEntry that refers to a
/// buffer.
static unsigned CreateSLocBufferAbbrev(llvm::BitstreamWriter &Stream) {
  using namespace llvm;
  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SM_SLOC_BUFFER_ENTRY));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Offset
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Include location
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2)); // Characteristic
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Line directives
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Buffer name blob
  return Stream.EmitAbbrev(Abbrev);
}

/// \brief Create an abbreviation for the SLocEntry that refers to a
/// buffer's blob.
static unsigned CreateSLocBufferBlobAbbrev(llvm::BitstreamWriter &Stream) {
  using namespace llvm;
  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SM_SLOC_BUFFER_BLOB));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Blob
  return Stream.EmitAbbrev(Abbrev);
}

/// \brief Create an abbreviation for the SLocEntry that refers to a macro
/// expansion.
static unsigned CreateSLocExpansionAbbrev(llvm::BitstreamWriter &Stream) {
  using namespace llvm;
  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SM_SLOC_EXPANSION_ENTRY));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Offset
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Spelling location
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Start location
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // End location
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Token length
  return Stream.EmitAbbrev(Abbrev);
}

namespace {
  // Trait used for the on-disk hash table of header search information.
  class HeaderFileInfoTrait {
    ASTWriter &Writer;
    const HeaderSearch &HS;
    
    // Keep track of the framework names we've used during serialization.
    SmallVector<char, 128> FrameworkStringData;
    llvm::StringMap<unsigned> FrameworkNameOffset;
    
  public:
    HeaderFileInfoTrait(ASTWriter &Writer, const HeaderSearch &HS)
      : Writer(Writer), HS(HS) { }
    
    struct key_type {
      const FileEntry *FE;
      const char *Filename;
    };
    typedef const key_type &key_type_ref;
    
    typedef HeaderFileInfo data_type;
    typedef const data_type &data_type_ref;
    typedef unsigned hash_value_type;
    typedef unsigned offset_type;
    
    static hash_value_type ComputeHash(key_type_ref key) {
      // The hash is based only on size/time of the file, so that the reader can
      // match even when symlinking or excess path elements ("foo/../", "../")
      // change the form of the name. However, complete path is still the key.
      return llvm::hash_combine(key.FE->getSize(),
                                key.FE->getModificationTime());
    }
    
    std::pair<unsigned,unsigned>
    EmitKeyDataLength(raw_ostream& Out, key_type_ref key, data_type_ref Data) {
      using namespace llvm::support;
      endian::Writer<little> Writer(Out);
      unsigned KeyLen = strlen(key.Filename) + 1 + 8 + 8;
      Writer.write<uint16_t>(KeyLen);
      unsigned DataLen = 1 + 2 + 4 + 4;
      if (Data.isModuleHeader)
        DataLen += 4;
      Writer.write<uint8_t>(DataLen);
      return std::make_pair(KeyLen, DataLen);
    }
    
    void EmitKey(raw_ostream& Out, key_type_ref key, unsigned KeyLen) {
      using namespace llvm::support;
      endian::Writer<little> LE(Out);
      LE.write<uint64_t>(key.FE->getSize());
      KeyLen -= 8;
      LE.write<uint64_t>(key.FE->getModificationTime());
      KeyLen -= 8;
      Out.write(key.Filename, KeyLen);
    }
    
    void EmitData(raw_ostream &Out, key_type_ref key,
                  data_type_ref Data, unsigned DataLen) {
      using namespace llvm::support;
      endian::Writer<little> LE(Out);
      uint64_t Start = Out.tell(); (void)Start;
      
      unsigned char Flags = (Data.HeaderRole << 6)
                          | (Data.isImport << 5)
                          | (Data.isPragmaOnce << 4)
                          | (Data.DirInfo << 2)
                          | (Data.Resolved << 1)
                          | Data.IndexHeaderMapHeader;
      LE.write<uint8_t>(Flags);
      LE.write<uint16_t>(Data.NumIncludes);
      
      if (!Data.ControllingMacro)
        LE.write<uint32_t>(Data.ControllingMacroID);
      else
        LE.write<uint32_t>(Writer.getIdentifierRef(Data.ControllingMacro));
      
      unsigned Offset = 0;
      if (!Data.Framework.empty()) {
        // If this header refers into a framework, save the framework name.
        llvm::StringMap<unsigned>::iterator Pos
          = FrameworkNameOffset.find(Data.Framework);
        if (Pos == FrameworkNameOffset.end()) {
          Offset = FrameworkStringData.size() + 1;
          FrameworkStringData.append(Data.Framework.begin(), 
                                     Data.Framework.end());
          FrameworkStringData.push_back(0);
          
          FrameworkNameOffset[Data.Framework] = Offset;
        } else
          Offset = Pos->second;
      }
      LE.write<uint32_t>(Offset);

      if (Data.isModuleHeader) {
        Module *Mod = HS.findModuleForHeader(key.FE).getModule();
        LE.write<uint32_t>(Writer.getExistingSubmoduleID(Mod));
      }

      assert(Out.tell() - Start == DataLen && "Wrong data length");
    }
    
    const char *strings_begin() const { return FrameworkStringData.begin(); }
    const char *strings_end() const { return FrameworkStringData.end(); }
  };
} // end anonymous namespace

/// \brief Write the header search block for the list of files that 
///
/// \param HS The header search structure to save.
void ASTWriter::WriteHeaderSearch(const HeaderSearch &HS, StringRef isysroot) {
  SmallVector<const FileEntry *, 16> FilesByUID;
  HS.getFileMgr().GetUniqueIDMapping(FilesByUID);
  
  if (FilesByUID.size() > HS.header_file_size())
    FilesByUID.resize(HS.header_file_size());
  
  HeaderFileInfoTrait GeneratorTrait(*this, HS);
  llvm::OnDiskChainedHashTableGenerator<HeaderFileInfoTrait> Generator;
  SmallVector<const char *, 4> SavedStrings;
  unsigned NumHeaderSearchEntries = 0;
  for (unsigned UID = 0, LastUID = FilesByUID.size(); UID != LastUID; ++UID) {
    const FileEntry *File = FilesByUID[UID];
    if (!File)
      continue;

    // Use HeaderSearch's getFileInfo to make sure we get the HeaderFileInfo
    // from the external source if it was not provided already.
    HeaderFileInfo HFI;
    if (!HS.tryGetFileInfo(File, HFI) ||
        (HFI.External && Chain) ||
        (HFI.isModuleHeader && !HFI.isCompilingModuleHeader))
      continue;

    // Turn the file name into an absolute path, if it isn't already.
    const char *Filename = File->getName();
    Filename = adjustFilenameForRelocatablePCH(Filename, isysroot);
      
    // If we performed any translation on the file name at all, we need to
    // save this string, since the generator will refer to it later.
    if (Filename != File->getName()) {
      Filename = strdup(Filename);
      SavedStrings.push_back(Filename);
    }
    
    HeaderFileInfoTrait::key_type key = { File, Filename };
    Generator.insert(key, HFI, GeneratorTrait);
    ++NumHeaderSearchEntries;
  }
  
  // Create the on-disk hash table in a buffer.
  SmallString<4096> TableData;
  uint32_t BucketOffset;
  {
    using namespace llvm::support;
    llvm::raw_svector_ostream Out(TableData);
    // Make sure that no bucket is at offset 0
    endian::Writer<little>(Out).write<uint32_t>(0);
    BucketOffset = Generator.Emit(Out, GeneratorTrait);
  }

  // Create a blob abbreviation
  using namespace llvm;
  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(HEADER_SEARCH_TABLE));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
  unsigned TableAbbrev = Stream.EmitAbbrev(Abbrev);
  
  // Write the header search table
  RecordData Record;
  Record.push_back(HEADER_SEARCH_TABLE);
  Record.push_back(BucketOffset);
  Record.push_back(NumHeaderSearchEntries);
  Record.push_back(TableData.size());
  TableData.append(GeneratorTrait.strings_begin(),GeneratorTrait.strings_end());
  Stream.EmitRecordWithBlob(TableAbbrev, Record, TableData.str());
  
  // Free all of the strings we had to duplicate.
  for (unsigned I = 0, N = SavedStrings.size(); I != N; ++I)
    free(const_cast<char *>(SavedStrings[I]));
}

/// \brief Writes the block containing the serialized form of the
/// source manager.
///
/// TODO: We should probably use an on-disk hash table (stored in a
/// blob), indexed based on the file name, so that we only create
/// entries for files that we actually need. In the common case (no
/// errors), we probably won't have to create file entries for any of
/// the files in the AST.
void ASTWriter::WriteSourceManagerBlock(SourceManager &SourceMgr,
                                        const Preprocessor &PP,
                                        StringRef isysroot) {
  RecordData Record;

  // Enter the source manager block.
  Stream.EnterSubblock(SOURCE_MANAGER_BLOCK_ID, 3);

  // Abbreviations for the various kinds of source-location entries.
  unsigned SLocFileAbbrv = CreateSLocFileAbbrev(Stream);
  unsigned SLocBufferAbbrv = CreateSLocBufferAbbrev(Stream);
  unsigned SLocBufferBlobAbbrv = CreateSLocBufferBlobAbbrev(Stream);
  unsigned SLocExpansionAbbrv = CreateSLocExpansionAbbrev(Stream);

  // Write out the source location entry table. We skip the first
  // entry, which is always the same dummy entry.
  std::vector<uint32_t> SLocEntryOffsets;
  RecordData PreloadSLocs;
  SLocEntryOffsets.reserve(SourceMgr.local_sloc_entry_size() - 1);
  for (unsigned I = 1, N = SourceMgr.local_sloc_entry_size();
       I != N; ++I) {
    // Get this source location entry.
    const SrcMgr::SLocEntry *SLoc = &SourceMgr.getLocalSLocEntry(I);
    FileID FID = FileID::get(I);
    assert(&SourceMgr.getSLocEntry(FID) == SLoc);

    // Record the offset of this source-location entry.
    SLocEntryOffsets.push_back(Stream.GetCurrentBitNo());

    // Figure out which record code to use.
    unsigned Code;
    if (SLoc->isFile()) {
      const SrcMgr::ContentCache *Cache = SLoc->getFile().getContentCache();
      if (Cache->OrigEntry) {
        Code = SM_SLOC_FILE_ENTRY;
      } else
        Code = SM_SLOC_BUFFER_ENTRY;
    } else
      Code = SM_SLOC_EXPANSION_ENTRY;
    Record.clear();
    Record.push_back(Code);

    // Starting offset of this entry within this module, so skip the dummy.
    Record.push_back(SLoc->getOffset() - 2);
    if (SLoc->isFile()) {
      const SrcMgr::FileInfo &File = SLoc->getFile();
      Record.push_back(File.getIncludeLoc().getRawEncoding());
      Record.push_back(File.getFileCharacteristic()); // FIXME: stable encoding
      Record.push_back(File.hasLineDirectives());

      const SrcMgr::ContentCache *Content = File.getContentCache();
      if (Content->OrigEntry) {
        assert(Content->OrigEntry == Content->ContentsEntry &&
               "Writing to AST an overridden file is not supported");

        // The source location entry is a file. Emit input file ID.
        assert(InputFileIDs[Content->OrigEntry] != 0 && "Missed file entry");
        Record.push_back(InputFileIDs[Content->OrigEntry]);

        Record.push_back(File.NumCreatedFIDs);
        
        FileDeclIDsTy::iterator FDI = FileDeclIDs.find(FID);
        if (FDI != FileDeclIDs.end()) {
          Record.push_back(FDI->second->FirstDeclIndex);
          Record.push_back(FDI->second->DeclIDs.size());
        } else {
          Record.push_back(0);
          Record.push_back(0);
        }
        
        Stream.EmitRecordWithAbbrev(SLocFileAbbrv, Record);
        
        if (Content->BufferOverridden) {
          Record.clear();
          Record.push_back(SM_SLOC_BUFFER_BLOB);
          const llvm::MemoryBuffer *Buffer
            = Content->getBuffer(PP.getDiagnostics(), PP.getSourceManager());
          Stream.EmitRecordWithBlob(SLocBufferBlobAbbrv, Record,
                                    StringRef(Buffer->getBufferStart(),
                                              Buffer->getBufferSize() + 1));          
        }
      } else {
        // The source location entry is a buffer. The blob associated
        // with this entry contains the contents of the buffer.

        // We add one to the size so that we capture the trailing NULL
        // that is required by llvm::MemoryBuffer::getMemBuffer (on
        // the reader side).
        const llvm::MemoryBuffer *Buffer
          = Content->getBuffer(PP.getDiagnostics(), PP.getSourceManager());
        const char *Name = Buffer->getBufferIdentifier();
        Stream.EmitRecordWithBlob(SLocBufferAbbrv, Record,
                                  StringRef(Name, strlen(Name) + 1));
        Record.clear();
        Record.push_back(SM_SLOC_BUFFER_BLOB);
        Stream.EmitRecordWithBlob(SLocBufferBlobAbbrv, Record,
                                  StringRef(Buffer->getBufferStart(),
                                                  Buffer->getBufferSize() + 1));

        if (strcmp(Name, "<built-in>") == 0) {
          PreloadSLocs.push_back(SLocEntryOffsets.size());
        }
      }
    } else {
      // The source location entry is a macro expansion.
      const SrcMgr::ExpansionInfo &Expansion = SLoc->getExpansion();
      Record.push_back(Expansion.getSpellingLoc().getRawEncoding());
      Record.push_back(Expansion.getExpansionLocStart().getRawEncoding());
      Record.push_back(Expansion.isMacroArgExpansion() ? 0
                             : Expansion.getExpansionLocEnd().getRawEncoding());

      // Compute the token length for this macro expansion.
      unsigned NextOffset = SourceMgr.getNextLocalOffset();
      if (I + 1 != N)
        NextOffset = SourceMgr.getLocalSLocEntry(I + 1).getOffset();
      Record.push_back(NextOffset - SLoc->getOffset() - 1);
      Stream.EmitRecordWithAbbrev(SLocExpansionAbbrv, Record);
    }
  }

  Stream.ExitBlock();

  if (SLocEntryOffsets.empty())
    return;

  // Write the source-location offsets table into the AST block. This
  // table is used for lazily loading source-location information.
  using namespace llvm;
  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SOURCE_LOCATION_OFFSETS));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 16)); // # of slocs
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 16)); // total size
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // offsets
  unsigned SLocOffsetsAbbrev = Stream.EmitAbbrev(Abbrev);

  Record.clear();
  Record.push_back(SOURCE_LOCATION_OFFSETS);
  Record.push_back(SLocEntryOffsets.size());
  Record.push_back(SourceMgr.getNextLocalOffset() - 1); // skip dummy
  Stream.EmitRecordWithBlob(SLocOffsetsAbbrev, Record, data(SLocEntryOffsets));

  // Write the source location entry preloads array, telling the AST
  // reader which source locations entries it should load eagerly.
  Stream.EmitRecord(SOURCE_LOCATION_PRELOADS, PreloadSLocs);

  // Write the line table. It depends on remapping working, so it must come
  // after the source location offsets.
  if (SourceMgr.hasLineTable()) {
    LineTableInfo &LineTable = SourceMgr.getLineTable();

    Record.clear();
    // Emit the file names
    Record.push_back(LineTable.getNumFilenames());
    for (unsigned I = 0, N = LineTable.getNumFilenames(); I != N; ++I) {
      // Emit the file name
      const char *Filename = LineTable.getFilename(I);
      Filename = adjustFilenameForRelocatablePCH(Filename, isysroot);
      unsigned FilenameLen = Filename? strlen(Filename) : 0;
      Record.push_back(FilenameLen);
      if (FilenameLen)
        Record.insert(Record.end(), Filename, Filename + FilenameLen);
    }

    // Emit the line entries
    for (LineTableInfo::iterator L = LineTable.begin(), LEnd = LineTable.end();
         L != LEnd; ++L) {
      // Only emit entries for local files.
      if (L->first.ID < 0)
        continue;

      // Emit the file ID
      Record.push_back(L->first.ID);

      // Emit the line entries
      Record.push_back(L->second.size());
      for (std::vector<LineEntry>::iterator LE = L->second.begin(),
                                         LEEnd = L->second.end();
           LE != LEEnd; ++LE) {
        Record.push_back(LE->FileOffset);
        Record.push_back(LE->LineNo);
        Record.push_back(LE->FilenameID);
        Record.push_back((unsigned)LE->FileKind);
        Record.push_back(LE->IncludeOffset);
      }
    }
    Stream.EmitRecord(SOURCE_MANAGER_LINE_TABLE, Record);
  }
}

//===----------------------------------------------------------------------===//
// Preprocessor Serialization
//===----------------------------------------------------------------------===//

namespace {
class ASTMacroTableTrait {
public:
  typedef IdentID key_type;
  typedef key_type key_type_ref;

  struct Data {
    uint32_t MacroDirectivesOffset;
  };

  typedef Data data_type;
  typedef const data_type &data_type_ref;
  typedef unsigned hash_value_type;
  typedef unsigned offset_type;

  static hash_value_type ComputeHash(IdentID IdID) {
    return llvm::hash_value(IdID);
  }

  std::pair<unsigned,unsigned>
  static EmitKeyDataLength(raw_ostream& Out,
                           key_type_ref Key, data_type_ref Data) {
    unsigned KeyLen = 4; // IdentID.
    unsigned DataLen = 4; // MacroDirectivesOffset.
    return std::make_pair(KeyLen, DataLen);
  }

  static void EmitKey(raw_ostream& Out, key_type_ref Key, unsigned KeyLen) {
    using namespace llvm::support;
    endian::Writer<little>(Out).write<uint32_t>(Key);
  }

  static void EmitData(raw_ostream& Out, key_type_ref Key, data_type_ref Data,
                       unsigned) {
    using namespace llvm::support;
    endian::Writer<little>(Out).write<uint32_t>(Data.MacroDirectivesOffset);
  }
};
} // end anonymous namespace

static int compareMacroDirectives(
    const std::pair<const IdentifierInfo *, MacroDirective *> *X,
    const std::pair<const IdentifierInfo *, MacroDirective *> *Y) {
  return X->first->getName().compare(Y->first->getName());
}

static bool shouldIgnoreMacro(MacroDirective *MD, bool IsModule,
                              const Preprocessor &PP) {
  if (MacroInfo *MI = MD->getMacroInfo())
    if (MI->isBuiltinMacro())
      return true;

  if (IsModule) {
    SourceLocation Loc = MD->getLocation();
    if (Loc.isInvalid())
      return true;
    if (PP.getSourceManager().getFileID(Loc) == PP.getPredefinesFileID())
      return true;
  }

  return false;
}

/// \brief Writes the block containing the serialized form of the
/// preprocessor.
///
void ASTWriter::WritePreprocessor(const Preprocessor &PP, bool IsModule) {
  PreprocessingRecord *PPRec = PP.getPreprocessingRecord();
  if (PPRec)
    WritePreprocessorDetail(*PPRec);

  RecordData Record;

  // If the preprocessor __COUNTER__ value has been bumped, remember it.
  if (PP.getCounterValue() != 0) {
    Record.push_back(PP.getCounterValue());
    Stream.EmitRecord(PP_COUNTER_VALUE, Record);
    Record.clear();
  }

  // Enter the preprocessor block.
  Stream.EnterSubblock(PREPROCESSOR_BLOCK_ID, 3);

  // If the AST file contains __DATE__ or __TIME__ emit a warning about this.
  // FIXME: use diagnostics subsystem for localization etc.
  if (PP.SawDateOrTime())
    fprintf(stderr, "warning: precompiled header used __DATE__ or __TIME__.\n");


  // Loop over all the macro directives that are live at the end of the file,
  // emitting each to the PP section.

  // Construct the list of macro directives that need to be serialized.
  SmallVector<std::pair<const IdentifierInfo *, MacroDirective *>, 2>
    MacroDirectives;
  for (Preprocessor::macro_iterator
         I = PP.macro_begin(/*IncludeExternalMacros=*/false),
         E = PP.macro_end(/*IncludeExternalMacros=*/false);
       I != E; ++I) {
    MacroDirectives.push_back(std::make_pair(I->first, I->second));
  }

  // Sort the set of macro definitions that need to be serialized by the
  // name of the macro, to provide a stable ordering.
  llvm::array_pod_sort(MacroDirectives.begin(), MacroDirectives.end(),
                       &compareMacroDirectives);

  llvm::OnDiskChainedHashTableGenerator<ASTMacroTableTrait> Generator;

  // Emit the macro directives as a list and associate the offset with the
  // identifier they belong to.
  for (unsigned I = 0, N = MacroDirectives.size(); I != N; ++I) {
    const IdentifierInfo *Name = MacroDirectives[I].first;
    uint64_t MacroDirectiveOffset = Stream.GetCurrentBitNo();
    MacroDirective *MD = MacroDirectives[I].second;

    // If the macro or identifier need no updates, don't write the macro history
    // for this one.
    // FIXME: Chain the macro history instead of re-writing it.
    if (MD->isFromPCH() &&
        Name->isFromAST() && !Name->hasChangedSinceDeserialization())
      continue;

    // Emit the macro directives in reverse source order.
    for (; MD; MD = MD->getPrevious()) {
      if (shouldIgnoreMacro(MD, IsModule, PP))
        continue;

      AddSourceLocation(MD->getLocation(), Record);
      Record.push_back(MD->getKind());
      if (DefMacroDirective *DefMD = dyn_cast<DefMacroDirective>(MD)) {
        MacroID InfoID = getMacroRef(DefMD->getInfo(), Name);
        Record.push_back(InfoID);
        Record.push_back(DefMD->isImported());
        Record.push_back(DefMD->isAmbiguous());

      } else if (VisibilityMacroDirective *
                   VisMD = dyn_cast<VisibilityMacroDirective>(MD)) {
        Record.push_back(VisMD->isPublic());
      }
    }
    if (Record.empty())
      continue;

    Stream.EmitRecord(PP_MACRO_DIRECTIVE_HISTORY, Record);
    Record.clear();

    IdentMacroDirectivesOffsetMap[Name] = MacroDirectiveOffset;

    IdentID NameID = getIdentifierRef(Name);
    ASTMacroTableTrait::Data data;
    data.MacroDirectivesOffset = MacroDirectiveOffset;
    Generator.insert(NameID, data);
  }

  /// \brief Offsets of each of the macros into the bitstream, indexed by
  /// the local macro ID
  ///
  /// For each identifier that is associated with a macro, this map
  /// provides the offset into the bitstream where that macro is
  /// defined.
  std::vector<uint32_t> MacroOffsets;

  for (unsigned I = 0, N = MacroInfosToEmit.size(); I != N; ++I) {
    const IdentifierInfo *Name = MacroInfosToEmit[I].Name;
    MacroInfo *MI = MacroInfosToEmit[I].MI;
    MacroID ID = MacroInfosToEmit[I].ID;

    if (ID < FirstMacroID) {
      assert(0 && "Loaded MacroInfo entered MacroInfosToEmit ?");
      continue;
    }

    // Record the local offset of this macro.
    unsigned Index = ID - FirstMacroID;
    if (Index == MacroOffsets.size())
      MacroOffsets.push_back(Stream.GetCurrentBitNo());
    else {
      if (Index > MacroOffsets.size())
        MacroOffsets.resize(Index + 1);

      MacroOffsets[Index] = Stream.GetCurrentBitNo();
    }

    AddIdentifierRef(Name, Record);
    Record.push_back(inferSubmoduleIDFromLocation(MI->getDefinitionLoc()));
    AddSourceLocation(MI->getDefinitionLoc(), Record);
    AddSourceLocation(MI->getDefinitionEndLoc(), Record);
    Record.push_back(MI->isUsed());
    Record.push_back(MI->isUsedForHeaderGuard());
    unsigned Code;
    if (MI->isObjectLike()) {
      Code = PP_MACRO_OBJECT_LIKE;
    } else {
      Code = PP_MACRO_FUNCTION_LIKE;

      Record.push_back(MI->isC99Varargs());
      Record.push_back(MI->isGNUVarargs());
      Record.push_back(MI->hasCommaPasting());
      Record.push_back(MI->getNumArgs());
      for (MacroInfo::arg_iterator I = MI->arg_begin(), E = MI->arg_end();
           I != E; ++I)
        AddIdentifierRef(*I, Record);
    }

    // If we have a detailed preprocessing record, record the macro definition
    // ID that corresponds to this macro.
    if (PPRec)
      Record.push_back(MacroDefinitions[PPRec->findMacroDefinition(MI)]);

    Stream.EmitRecord(Code, Record);
    Record.clear();

    // Emit the tokens array.
    for (unsigned TokNo = 0, e = MI->getNumTokens(); TokNo != e; ++TokNo) {
      // Note that we know that the preprocessor does not have any annotation
      // tokens in it because they are created by the parser, and thus can't
      // be in a macro definition.
      const Token &Tok = MI->getReplacementToken(TokNo);
      AddToken(Tok, Record);
      Stream.EmitRecord(PP_TOKEN, Record);
      Record.clear();
    }
    ++NumMacros;
  }

  Stream.ExitBlock();

  // Create the on-disk hash table in a buffer.
  SmallString<4096> MacroTable;
  uint32_t BucketOffset;
  {
    using namespace llvm::support;
    llvm::raw_svector_ostream Out(MacroTable);
    // Make sure that no bucket is at offset 0
    endian::Writer<little>(Out).write<uint32_t>(0);
    BucketOffset = Generator.Emit(Out);
  }

  // Write the macro table
  using namespace llvm;
  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(MACRO_TABLE));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
  unsigned MacroTableAbbrev = Stream.EmitAbbrev(Abbrev);

  Record.push_back(MACRO_TABLE);
  Record.push_back(BucketOffset);
  Stream.EmitRecordWithBlob(MacroTableAbbrev, Record, MacroTable.str());
  Record.clear();

  // Write the offsets table for macro IDs.
  using namespace llvm;
  Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(MACRO_OFFSET));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // # of macros
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // first ID
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));

  unsigned MacroOffsetAbbrev = Stream.EmitAbbrev(Abbrev);
  Record.clear();
  Record.push_back(MACRO_OFFSET);
  Record.push_back(MacroOffsets.size());
  Record.push_back(FirstMacroID - NUM_PREDEF_MACRO_IDS);
  Stream.EmitRecordWithBlob(MacroOffsetAbbrev, Record,
                            data(MacroOffsets));
}

void ASTWriter::WritePreprocessorDetail(PreprocessingRecord &PPRec) {
  if (PPRec.local_begin() == PPRec.local_end())
    return;

  SmallVector<PPEntityOffset, 64> PreprocessedEntityOffsets;

  // Enter the preprocessor block.
  Stream.EnterSubblock(PREPROCESSOR_DETAIL_BLOCK_ID, 3);

  // If the preprocessor has a preprocessing record, emit it.
  unsigned NumPreprocessingRecords = 0;
  using namespace llvm;
  
  // Set up the abbreviation for 
  unsigned InclusionAbbrev = 0;
  {
    BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
    Abbrev->Add(BitCodeAbbrevOp(PPD_INCLUSION_DIRECTIVE));
    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // filename length
    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // in quotes
    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2)); // kind
    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // imported module
    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
    InclusionAbbrev = Stream.EmitAbbrev(Abbrev);
  }
  
  unsigned FirstPreprocessorEntityID 
    = (Chain ? PPRec.getNumLoadedPreprocessedEntities() : 0) 
    + NUM_PREDEF_PP_ENTITY_IDS;
  unsigned NextPreprocessorEntityID = FirstPreprocessorEntityID;
  RecordData Record;
  for (PreprocessingRecord::iterator E = PPRec.local_begin(),
                                  EEnd = PPRec.local_end();
       E != EEnd; 
       (void)++E, ++NumPreprocessingRecords, ++NextPreprocessorEntityID) {
    Record.clear();

    PreprocessedEntityOffsets.push_back(PPEntityOffset((*E)->getSourceRange(),
                                                     Stream.GetCurrentBitNo()));

    if (MacroDefinition *MD = dyn_cast<MacroDefinition>(*E)) {
      // Record this macro definition's ID.
      MacroDefinitions[MD] = NextPreprocessorEntityID;
      
      AddIdentifierRef(MD->getName(), Record);
      Stream.EmitRecord(PPD_MACRO_DEFINITION, Record);
      continue;
    }

    if (MacroExpansion *ME = dyn_cast<MacroExpansion>(*E)) {
      Record.push_back(ME->isBuiltinMacro());
      if (ME->isBuiltinMacro())
        AddIdentifierRef(ME->getName(), Record);
      else
        Record.push_back(MacroDefinitions[ME->getDefinition()]);
      Stream.EmitRecord(PPD_MACRO_EXPANSION, Record);
      continue;
    }

    if (InclusionDirective *ID = dyn_cast<InclusionDirective>(*E)) {
      Record.push_back(PPD_INCLUSION_DIRECTIVE);
      Record.push_back(ID->getFileName().size());
      Record.push_back(ID->wasInQuotes());
      Record.push_back(static_cast<unsigned>(ID->getKind()));
      Record.push_back(ID->importedModule());
      SmallString<64> Buffer;
      Buffer += ID->getFileName();
      // Check that the FileEntry is not null because it was not resolved and
      // we create a PCH even with compiler errors.
      if (ID->getFile())
        Buffer += ID->getFile()->getName();
      Stream.EmitRecordWithBlob(InclusionAbbrev, Record, Buffer);
      continue;
    }
    
    llvm_unreachable("Unhandled PreprocessedEntity in ASTWriter");
  }
  Stream.ExitBlock();

  // Write the offsets table for the preprocessing record.
  if (NumPreprocessingRecords > 0) {
    assert(PreprocessedEntityOffsets.size() == NumPreprocessingRecords);

    // Write the offsets table for identifier IDs.
    using namespace llvm;
    BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
    Abbrev->Add(BitCodeAbbrevOp(PPD_ENTITIES_OFFSETS));
    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // first pp entity
    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
    unsigned PPEOffsetAbbrev = Stream.EmitAbbrev(Abbrev);

    Record.clear();
    Record.push_back(PPD_ENTITIES_OFFSETS);
    Record.push_back(FirstPreprocessorEntityID - NUM_PREDEF_PP_ENTITY_IDS);
    Stream.EmitRecordWithBlob(PPEOffsetAbbrev, Record,
                              data(PreprocessedEntityOffsets));
  }
}

unsigned ASTWriter::getSubmoduleID(Module *Mod) {
  llvm::DenseMap<Module *, unsigned>::iterator Known = SubmoduleIDs.find(Mod);
  if (Known != SubmoduleIDs.end())
    return Known->second;
  
  return SubmoduleIDs[Mod] = NextSubmoduleID++;
}

unsigned ASTWriter::getExistingSubmoduleID(Module *Mod) const {
  if (!Mod)
    return 0;

  llvm::DenseMap<Module *, unsigned>::const_iterator
    Known = SubmoduleIDs.find(Mod);
  if (Known != SubmoduleIDs.end())
    return Known->second;

  return 0;
}

/// \brief Compute the number of modules within the given tree (including the
/// given module).
static unsigned getNumberOfModules(Module *Mod) {
  unsigned ChildModules = 0;
  for (Module::submodule_iterator Sub = Mod->submodule_begin(),
                               SubEnd = Mod->submodule_end();
       Sub != SubEnd; ++Sub)
    ChildModules += getNumberOfModules(*Sub);
  
  return ChildModules + 1;
}

void ASTWriter::WriteSubmodules(Module *WritingModule) {
  // Determine the dependencies of our module and each of it's submodules.
  // FIXME: This feels like it belongs somewhere else, but there are no
  // other consumers of this information.
  SourceManager &SrcMgr = PP->getSourceManager();
  ModuleMap &ModMap = PP->getHeaderSearchInfo().getModuleMap();
  for (const auto *I : Context->local_imports()) {
    if (Module *ImportedFrom
          = ModMap.inferModuleFromLocation(FullSourceLoc(I->getLocation(), 
                                                         SrcMgr))) {
      ImportedFrom->Imports.push_back(I->getImportedModule());
    }
  }
  
  // Enter the submodule description block.
  Stream.EnterSubblock(SUBMODULE_BLOCK_ID, NUM_ALLOWED_ABBREVS_SIZE);
  
  // Write the abbreviations needed for the submodules block.
  using namespace llvm;
  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SUBMODULE_DEFINITION));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ID
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Parent
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // IsFramework
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // IsExplicit
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // IsSystem
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // IsExternC
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // InferSubmodules...
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // InferExplicit...
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // InferExportWild...
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // ConfigMacrosExh...
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Name
  unsigned DefinitionAbbrev = Stream.EmitAbbrev(Abbrev);

  Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SUBMODULE_UMBRELLA_HEADER));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Name
  unsigned UmbrellaAbbrev = Stream.EmitAbbrev(Abbrev);

  Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SUBMODULE_HEADER));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Name
  unsigned HeaderAbbrev = Stream.EmitAbbrev(Abbrev);

  Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SUBMODULE_TOPHEADER));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Name
  unsigned TopHeaderAbbrev = Stream.EmitAbbrev(Abbrev);

  Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SUBMODULE_UMBRELLA_DIR));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Name
  unsigned UmbrellaDirAbbrev = Stream.EmitAbbrev(Abbrev);

  Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SUBMODULE_REQUIRES));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // State
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));     // Feature
  unsigned RequiresAbbrev = Stream.EmitAbbrev(Abbrev);

  Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SUBMODULE_EXCLUDED_HEADER));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Name
  unsigned ExcludedHeaderAbbrev = Stream.EmitAbbrev(Abbrev);

  Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SUBMODULE_PRIVATE_HEADER));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Name
  unsigned PrivateHeaderAbbrev = Stream.EmitAbbrev(Abbrev);

  Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SUBMODULE_LINK_LIBRARY));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // IsFramework
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));     // Name
  unsigned LinkLibraryAbbrev = Stream.EmitAbbrev(Abbrev);

  Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SUBMODULE_CONFIG_MACRO));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));    // Macro name
  unsigned ConfigMacroAbbrev = Stream.EmitAbbrev(Abbrev);

  Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(SUBMODULE_CONFLICT));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));  // Other module
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));    // Message
  unsigned ConflictAbbrev = Stream.EmitAbbrev(Abbrev);

  // Write the submodule metadata block.
  RecordData Record;
  Record.push_back(getNumberOfModules(WritingModule));
  Record.push_back(FirstSubmoduleID - NUM_PREDEF_SUBMODULE_IDS);
  Stream.EmitRecord(SUBMODULE_METADATA, Record);
  
  // Write all of the submodules.
  std::queue<Module *> Q;
  Q.push(WritingModule);
  while (!Q.empty()) {
    Module *Mod = Q.front();
    Q.pop();
    unsigned ID = getSubmoduleID(Mod);
    
    // Emit the definition of the block.
    Record.clear();
    Record.push_back(SUBMODULE_DEFINITION);
    Record.push_back(ID);
    if (Mod->Parent) {
      assert(SubmoduleIDs[Mod->Parent] && "Submodule parent not written?");
      Record.push_back(SubmoduleIDs[Mod->Parent]);
    } else {
      Record.push_back(0);
    }
    Record.push_back(Mod->IsFramework);
    Record.push_back(Mod->IsExplicit);
    Record.push_back(Mod->IsSystem);
    Record.push_back(Mod->IsExternC);
    Record.push_back(Mod->InferSubmodules);
    Record.push_back(Mod->InferExplicitSubmodules);
    Record.push_back(Mod->InferExportWildcard);
    Record.push_back(Mod->ConfigMacrosExhaustive);
    Stream.EmitRecordWithBlob(DefinitionAbbrev, Record, Mod->Name);
    
    // Emit the requirements.
    for (unsigned I = 0, N = Mod->Requirements.size(); I != N; ++I) {
      Record.clear();
      Record.push_back(SUBMODULE_REQUIRES);
      Record.push_back(Mod->Requirements[I].second);
      Stream.EmitRecordWithBlob(RequiresAbbrev, Record,
                                Mod->Requirements[I].first);
    }

    // Emit the umbrella header, if there is one.
    if (const FileEntry *UmbrellaHeader = Mod->getUmbrellaHeader()) {
      Record.clear();
      Record.push_back(SUBMODULE_UMBRELLA_HEADER);
      Stream.EmitRecordWithBlob(UmbrellaAbbrev, Record, 
                                UmbrellaHeader->getName());
    } else if (const DirectoryEntry *UmbrellaDir = Mod->getUmbrellaDir()) {
      Record.clear();
      Record.push_back(SUBMODULE_UMBRELLA_DIR);
      Stream.EmitRecordWithBlob(UmbrellaDirAbbrev, Record, 
                                UmbrellaDir->getName());      
    }
    
    // Emit the headers.
    for (unsigned I = 0, N = Mod->NormalHeaders.size(); I != N; ++I) {
      Record.clear();
      Record.push_back(SUBMODULE_HEADER);
      Stream.EmitRecordWithBlob(HeaderAbbrev, Record, 
                                Mod->NormalHeaders[I]->getName());
    }
    // Emit the excluded headers.
    for (unsigned I = 0, N = Mod->ExcludedHeaders.size(); I != N; ++I) {
      Record.clear();
      Record.push_back(SUBMODULE_EXCLUDED_HEADER);
      Stream.EmitRecordWithBlob(ExcludedHeaderAbbrev, Record, 
                                Mod->ExcludedHeaders[I]->getName());
    }
    // Emit the private headers.
    for (unsigned I = 0, N = Mod->PrivateHeaders.size(); I != N; ++I) {
      Record.clear();
      Record.push_back(SUBMODULE_PRIVATE_HEADER);
      Stream.EmitRecordWithBlob(PrivateHeaderAbbrev, Record, 
                                Mod->PrivateHeaders[I]->getName());
    }
    ArrayRef<const FileEntry *>
      TopHeaders = Mod->getTopHeaders(PP->getFileManager());
    for (unsigned I = 0, N = TopHeaders.size(); I != N; ++I) {
      Record.clear();
      Record.push_back(SUBMODULE_TOPHEADER);
      Stream.EmitRecordWithBlob(TopHeaderAbbrev, Record,
                                TopHeaders[I]->getName());
    }

    // Emit the imports. 
    if (!Mod->Imports.empty()) {
      Record.clear();
      for (unsigned I = 0, N = Mod->Imports.size(); I != N; ++I) {
        unsigned ImportedID = getSubmoduleID(Mod->Imports[I]);
        assert(ImportedID && "Unknown submodule!");                                           
        Record.push_back(ImportedID);
      }
      Stream.EmitRecord(SUBMODULE_IMPORTS, Record);
    }

    // Emit the exports. 
    if (!Mod->Exports.empty()) {
      Record.clear();
      for (unsigned I = 0, N = Mod->Exports.size(); I != N; ++I) {
        if (Module *Exported = Mod->Exports[I].getPointer()) {
          unsigned ExportedID = SubmoduleIDs[Exported];
          assert(ExportedID > 0 && "Unknown submodule ID?");
          Record.push_back(ExportedID);
        } else {
          Record.push_back(0);
        }
        
        Record.push_back(Mod->Exports[I].getInt());
      }
      Stream.EmitRecord(SUBMODULE_EXPORTS, Record);
    }

    //FIXME: How do we emit the 'use'd modules?  They may not be submodules.
    // Might be unnecessary as use declarations are only used to build the
    // module itself.

    // Emit the link libraries.
    for (unsigned I = 0, N = Mod->LinkLibraries.size(); I != N; ++I) {
      Record.clear();
      Record.push_back(SUBMODULE_LINK_LIBRARY);
      Record.push_back(Mod->LinkLibraries[I].IsFramework);
      Stream.EmitRecordWithBlob(LinkLibraryAbbrev, Record,
                                Mod->LinkLibraries[I].Library);
    }

    // Emit the conflicts.
    for (unsigned I = 0, N = Mod->Conflicts.size(); I != N; ++I) {
      Record.clear();
      Record.push_back(SUBMODULE_CONFLICT);
      unsigned OtherID = getSubmoduleID(Mod->Conflicts[I].Other);
      assert(OtherID && "Unknown submodule!");
      Record.push_back(OtherID);
      Stream.EmitRecordWithBlob(ConflictAbbrev, Record,
                                Mod->Conflicts[I].Message);
    }

    // Emit the configuration macros.
    for (unsigned I = 0, N =  Mod->ConfigMacros.size(); I != N; ++I) {
      Record.clear();
      Record.push_back(SUBMODULE_CONFIG_MACRO);
      Stream.EmitRecordWithBlob(ConfigMacroAbbrev, Record,
                                Mod->ConfigMacros[I]);
    }

    // Queue up the submodules of this module.
    for (Module::submodule_iterator Sub = Mod->submodule_begin(),
                                 SubEnd = Mod->submodule_end();
         Sub != SubEnd; ++Sub)
      Q.push(*Sub);
  }
  
  Stream.ExitBlock();
  
  assert((NextSubmoduleID - FirstSubmoduleID
            == getNumberOfModules(WritingModule)) && "Wrong # of submodules");
}

serialization::SubmoduleID 
ASTWriter::inferSubmoduleIDFromLocation(SourceLocation Loc) {
  if (Loc.isInvalid() || !WritingModule)
    return 0; // No submodule
    
  // Find the module that owns this location.
  ModuleMap &ModMap = PP->getHeaderSearchInfo().getModuleMap();
  Module *OwningMod 
    = ModMap.inferModuleFromLocation(FullSourceLoc(Loc,PP->getSourceManager()));
  if (!OwningMod)
    return 0;
  
  // Check whether this submodule is part of our own module.
  if (WritingModule != OwningMod && !OwningMod->isSubModuleOf(WritingModule))
    return 0;
  
  return getSubmoduleID(OwningMod);
}

void ASTWriter::WritePragmaDiagnosticMappings(const DiagnosticsEngine &Diag,
                                              bool isModule) {
  // Make sure set diagnostic pragmas don't affect the translation unit that
  // imports the module.
  // FIXME: Make diagnostic pragma sections work properly with modules.
  if (isModule)
    return;

  llvm::SmallDenseMap<const DiagnosticsEngine::DiagState *, unsigned, 64>
      DiagStateIDMap;
  unsigned CurrID = 0;
  DiagStateIDMap[&Diag.DiagStates.front()] = ++CurrID; // the command-line one.
  RecordData Record;
  for (DiagnosticsEngine::DiagStatePointsTy::const_iterator
         I = Diag.DiagStatePoints.begin(), E = Diag.DiagStatePoints.end();
         I != E; ++I) {
    const DiagnosticsEngine::DiagStatePoint &point = *I;
    if (point.Loc.isInvalid())
      continue;

    Record.push_back(point.Loc.getRawEncoding());
    unsigned &DiagStateID = DiagStateIDMap[point.State];
    Record.push_back(DiagStateID);
    
    if (DiagStateID == 0) {
      DiagStateID = ++CurrID;
      for (DiagnosticsEngine::DiagState::const_iterator
             I = point.State->begin(), E = point.State->end(); I != E; ++I) {
        if (I->second.isPragma()) {
          Record.push_back(I->first);
          Record.push_back(I->second.getMapping());
        }
      }
      Record.push_back(-1); // mark the end of the diag/map pairs for this
                            // location.
    }
  }

  if (!Record.empty())
    Stream.EmitRecord(DIAG_PRAGMA_MAPPINGS, Record);
}

void ASTWriter::WriteCXXBaseSpecifiersOffsets() {
  if (CXXBaseSpecifiersOffsets.empty())
    return;

  RecordData Record;

  // Create a blob abbreviation for the C++ base specifiers offsets.
  using namespace llvm;
    
  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
  Abbrev->Add(BitCodeAbbrevOp(CXX_BASE_SPECIFIER_OFFSETS));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // size
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
  unsigned BaseSpecifierOffsetAbbrev = Stream.EmitAbbrev(Abbrev);
  
  // Write the base specifier offsets table.
  Record.clear();
  Record.push_back(CXX_BASE_SPECIFIER_OFFSETS);
  Record.push_back(CXXBaseSpecifiersOffsets.size());
  Stream.EmitRecordWithBlob(BaseSpecifierOffsetAbbrev, Record,
                            data(CXXBaseSpecifiersOffsets));
}

//===----------------------------------------------------------------------===//
// Type Serialization
//===----------------------------------------------------------------------===//

/// \brief Write the representation of a type to the AST stream.
void ASTWriter::WriteType(QualType T) {
  TypeIdx &Idx = TypeIdxs[T];
  if (Idx.getIndex() == 0) // we haven't seen this type before.
    Idx = TypeIdx(NextTypeID++);

  assert(Idx.getIndex() >= FirstTypeID && "Re-writing a type from a prior AST");

  // Record the offset for this type.
  unsigned Index = Idx.getIndex() - FirstTypeID;
  if (TypeOffsets.size() == Index)
    TypeOffsets.push_back(Stream.GetCurrentBitNo());
  else if (TypeOffsets.size() < Index) {
    TypeOffsets.resize(Index + 1);
    TypeOffsets[Index] = Stream.GetCurrentBitNo();
  }

  RecordData Record;

  // Emit the type's representation.
  ASTTypeWriter W(*this, Record);

  if (T.hasLocalNonFastQualifiers()) {
    Qualifiers Qs = T.getLocalQualifiers();
    AddTypeRef(T.getLocalUnqualifiedType(), Record);
    Record.push_back(Qs.getAsOpaqueValue());
    W.Code = TYPE_EXT_QUAL;
  } else {
    switch (T->getTypeClass()) {
      // For all of the concrete, non-dependent types, call the
      // appropriate visitor function.
#define TYPE(Class, Base) \
    case Type::Class: W.Visit##Class##Type(cast<Class##Type>(T)); break;
#define ABSTRACT_TYPE(Class, Base)
#include "clang/AST/TypeNodes.def"
    }
  }

  // Emit the serialized record.
  Stream.EmitRecord(W.Code, Record);

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

//===----------------------------------------------------------------------===//
// Declaration Serialization
//===----------------------------------------------------------------------===//

/// \brief Write the block containing all of the declaration IDs
/// lexically declared within the given DeclContext.
///
/// \returns the offset of the DECL_CONTEXT_LEXICAL block within the
/// bistream, or 0 if no block was written.
uint64_t ASTWriter::WriteDeclContextLexicalBlock(ASTContext &Context,
                                                 DeclContext *DC) {
  if