Reintroduce the serialization library, with fixed dependencies.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@111279 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/PCHWriter.cpp b/lib/Serialization/PCHWriter.cpp
new file mode 100644
index 0000000..2cb2758
--- /dev/null
+++ b/lib/Serialization/PCHWriter.cpp
@@ -0,0 +1,3094 @@
+//===--- PCHWriter.cpp - Precompiled Headers 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 PCHWriter class, which writes a precompiled header.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Serialization/PCHWriter.h"
+#include "clang/Sema/Sema.h"
+#include "clang/Sema/IdentifierResolver.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/DeclContextInternals.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/Type.h"
+#include "clang/AST/TypeLocVisitor.h"
+#include "clang/Serialization/PCHReader.h"
+#include "clang/Lex/MacroInfo.h"
+#include "clang/Lex/PreprocessingRecord.h"
+#include "clang/Lex/Preprocessor.h"
+#include "clang/Lex/HeaderSearch.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/OnDiskHashTable.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Basic/SourceManagerInternals.h"
+#include "clang/Basic/TargetInfo.h"
+#include "clang/Basic/Version.h"
+#include "llvm/ADT/APFloat.h"
+#include "llvm/ADT/APInt.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Bitcode/BitstreamWriter.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/System/Path.h"
+#include <cstdio>
+using namespace clang;
+
+template <typename T, typename Allocator>
+T *data(std::vector<T, Allocator> &v) {
+  return v.empty() ? 0 : &v.front();
+}
+template <typename T, typename Allocator>
+const T *data(const std::vector<T, Allocator> &v) {
+  return v.empty() ? 0 : &v.front();
+}
+
+//===----------------------------------------------------------------------===//
+// Type serialization
+//===----------------------------------------------------------------------===//
+
+namespace {
+  class PCHTypeWriter {
+    PCHWriter &Writer;
+    PCHWriter::RecordData &Record;
+
+  public:
+    /// \brief Type code that corresponds to the record generated.
+    pch::TypeCode Code;
+
+    PCHTypeWriter(PCHWriter &Writer, PCHWriter::RecordData &Record)
+      : Writer(Writer), Record(Record), Code(pch::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 PCHTypeWriter::VisitBuiltinType(const BuiltinType *T) {
+  assert(false && "Built-in types are never serialized");
+}
+
+void PCHTypeWriter::VisitComplexType(const ComplexType *T) {
+  Writer.AddTypeRef(T->getElementType(), Record);
+  Code = pch::TYPE_COMPLEX;
+}
+
+void PCHTypeWriter::VisitPointerType(const PointerType *T) {
+  Writer.AddTypeRef(T->getPointeeType(), Record);
+  Code = pch::TYPE_POINTER;
+}
+
+void PCHTypeWriter::VisitBlockPointerType(const BlockPointerType *T) {
+  Writer.AddTypeRef(T->getPointeeType(), Record);
+  Code = pch::TYPE_BLOCK_POINTER;
+}
+
+void PCHTypeWriter::VisitLValueReferenceType(const LValueReferenceType *T) {
+  Writer.AddTypeRef(T->getPointeeType(), Record);
+  Code = pch::TYPE_LVALUE_REFERENCE;
+}
+
+void PCHTypeWriter::VisitRValueReferenceType(const RValueReferenceType *T) {
+  Writer.AddTypeRef(T->getPointeeType(), Record);
+  Code = pch::TYPE_RVALUE_REFERENCE;
+}
+
+void PCHTypeWriter::VisitMemberPointerType(const MemberPointerType *T) {
+  Writer.AddTypeRef(T->getPointeeType(), Record);
+  Writer.AddTypeRef(QualType(T->getClass(), 0), Record);
+  Code = pch::TYPE_MEMBER_POINTER;
+}
+
+void PCHTypeWriter::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 PCHTypeWriter::VisitConstantArrayType(const ConstantArrayType *T) {
+  VisitArrayType(T);
+  Writer.AddAPInt(T->getSize(), Record);
+  Code = pch::TYPE_CONSTANT_ARRAY;
+}
+
+void PCHTypeWriter::VisitIncompleteArrayType(const IncompleteArrayType *T) {
+  VisitArrayType(T);
+  Code = pch::TYPE_INCOMPLETE_ARRAY;
+}
+
+void PCHTypeWriter::VisitVariableArrayType(const VariableArrayType *T) {
+  VisitArrayType(T);
+  Writer.AddSourceLocation(T->getLBracketLoc(), Record);
+  Writer.AddSourceLocation(T->getRBracketLoc(), Record);
+  Writer.AddStmt(T->getSizeExpr());
+  Code = pch::TYPE_VARIABLE_ARRAY;
+}
+
+void PCHTypeWriter::VisitVectorType(const VectorType *T) {
+  Writer.AddTypeRef(T->getElementType(), Record);
+  Record.push_back(T->getNumElements());
+  Record.push_back(T->getAltiVecSpecific());
+  Code = pch::TYPE_VECTOR;
+}
+
+void PCHTypeWriter::VisitExtVectorType(const ExtVectorType *T) {
+  VisitVectorType(T);
+  Code = pch::TYPE_EXT_VECTOR;
+}
+
+void PCHTypeWriter::VisitFunctionType(const FunctionType *T) {
+  Writer.AddTypeRef(T->getResultType(), Record);
+  FunctionType::ExtInfo C = T->getExtInfo();
+  Record.push_back(C.getNoReturn());
+  Record.push_back(C.getRegParm());
+  // FIXME: need to stabilize encoding of calling convention...
+  Record.push_back(C.getCC());
+}
+
+void PCHTypeWriter::VisitFunctionNoProtoType(const FunctionNoProtoType *T) {
+  VisitFunctionType(T);
+  Code = pch::TYPE_FUNCTION_NO_PROTO;
+}
+
+void PCHTypeWriter::VisitFunctionProtoType(const FunctionProtoType *T) {
+  VisitFunctionType(T);
+  Record.push_back(T->getNumArgs());
+  for (unsigned I = 0, N = T->getNumArgs(); I != N; ++I)
+    Writer.AddTypeRef(T->getArgType(I), Record);
+  Record.push_back(T->isVariadic());
+  Record.push_back(T->getTypeQuals());
+  Record.push_back(T->hasExceptionSpec());
+  Record.push_back(T->hasAnyExceptionSpec());
+  Record.push_back(T->getNumExceptions());
+  for (unsigned I = 0, N = T->getNumExceptions(); I != N; ++I)
+    Writer.AddTypeRef(T->getExceptionType(I), Record);
+  Code = pch::TYPE_FUNCTION_PROTO;
+}
+
+void PCHTypeWriter::VisitUnresolvedUsingType(const UnresolvedUsingType *T) {
+  Writer.AddDeclRef(T->getDecl(), Record);
+  Code = pch::TYPE_UNRESOLVED_USING;
+}
+
+void PCHTypeWriter::VisitTypedefType(const TypedefType *T) {
+  Writer.AddDeclRef(T->getDecl(), Record);
+  assert(!T->isCanonicalUnqualified() && "Invalid typedef ?");
+  Writer.AddTypeRef(T->getCanonicalTypeInternal(), Record);
+  Code = pch::TYPE_TYPEDEF;
+}
+
+void PCHTypeWriter::VisitTypeOfExprType(const TypeOfExprType *T) {
+  Writer.AddStmt(T->getUnderlyingExpr());
+  Code = pch::TYPE_TYPEOF_EXPR;
+}
+
+void PCHTypeWriter::VisitTypeOfType(const TypeOfType *T) {
+  Writer.AddTypeRef(T->getUnderlyingType(), Record);
+  Code = pch::TYPE_TYPEOF;
+}
+
+void PCHTypeWriter::VisitDecltypeType(const DecltypeType *T) {
+  Writer.AddStmt(T->getUnderlyingExpr());
+  Code = pch::TYPE_DECLTYPE;
+}
+
+void PCHTypeWriter::VisitTagType(const TagType *T) {
+  Record.push_back(T->isDependentType());
+  Writer.AddDeclRef(T->getDecl(), Record);
+  assert(!T->isBeingDefined() &&
+         "Cannot serialize in the middle of a type definition");
+}
+
+void PCHTypeWriter::VisitRecordType(const RecordType *T) {
+  VisitTagType(T);
+  Code = pch::TYPE_RECORD;
+}
+
+void PCHTypeWriter::VisitEnumType(const EnumType *T) {
+  VisitTagType(T);
+  Code = pch::TYPE_ENUM;
+}
+
+void
+PCHTypeWriter::VisitSubstTemplateTypeParmType(
+                                        const SubstTemplateTypeParmType *T) {
+  Writer.AddTypeRef(QualType(T->getReplacedParameter(), 0), Record);
+  Writer.AddTypeRef(T->getReplacementType(), Record);
+  Code = pch::TYPE_SUBST_TEMPLATE_TYPE_PARM;
+}
+
+void
+PCHTypeWriter::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->isCanonicalUnqualified() ? QualType()
+                                                : T->getCanonicalTypeInternal(),
+                    Record);
+  Code = pch::TYPE_TEMPLATE_SPECIALIZATION;
+}
+
+void
+PCHTypeWriter::VisitDependentSizedArrayType(const DependentSizedArrayType *T) {
+  VisitArrayType(T);
+  Writer.AddStmt(T->getSizeExpr());
+  Writer.AddSourceRange(T->getBracketsRange(), Record);
+  Code = pch::TYPE_DEPENDENT_SIZED_ARRAY;
+}
+
+void
+PCHTypeWriter::VisitDependentSizedExtVectorType(
+                                        const DependentSizedExtVectorType *T) {
+  // FIXME: Serialize this type (C++ only)
+  assert(false && "Cannot serialize dependent sized extended vector types");
+}
+
+void
+PCHTypeWriter::VisitTemplateTypeParmType(const TemplateTypeParmType *T) {
+  Record.push_back(T->getDepth());
+  Record.push_back(T->getIndex());
+  Record.push_back(T->isParameterPack());
+  Writer.AddIdentifierRef(T->getName(), Record);
+  Code = pch::TYPE_TEMPLATE_TYPE_PARM;
+}
+
+void
+PCHTypeWriter::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 = pch::TYPE_DEPENDENT_NAME;
+}
+
+void
+PCHTypeWriter::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 = pch::TYPE_DEPENDENT_TEMPLATE_SPECIALIZATION;
+}
+
+void PCHTypeWriter::VisitElaboratedType(const ElaboratedType *T) {
+  Record.push_back(T->getKeyword());
+  Writer.AddNestedNameSpecifier(T->getQualifier(), Record);
+  Writer.AddTypeRef(T->getNamedType(), Record);
+  Code = pch::TYPE_ELABORATED;
+}
+
+void PCHTypeWriter::VisitInjectedClassNameType(const InjectedClassNameType *T) {
+  Writer.AddDeclRef(T->getDecl(), Record);
+  Writer.AddTypeRef(T->getInjectedSpecializationType(), Record);
+  Code = pch::TYPE_INJECTED_CLASS_NAME;
+}
+
+void PCHTypeWriter::VisitObjCInterfaceType(const ObjCInterfaceType *T) {
+  Writer.AddDeclRef(T->getDecl(), Record);
+  Code = pch::TYPE_OBJC_INTERFACE;
+}
+
+void PCHTypeWriter::VisitObjCObjectType(const ObjCObjectType *T) {
+  Writer.AddTypeRef(T->getBaseType(), Record);
+  Record.push_back(T->getNumProtocols());
+  for (ObjCObjectType::qual_iterator I = T->qual_begin(),
+       E = T->qual_end(); I != E; ++I)
+    Writer.AddDeclRef(*I, Record);
+  Code = pch::TYPE_OBJC_OBJECT;
+}
+
+void
+PCHTypeWriter::VisitObjCObjectPointerType(const ObjCObjectPointerType *T) {
+  Writer.AddTypeRef(T->getPointeeType(), Record);
+  Code = pch::TYPE_OBJC_OBJECT_POINTER;
+}
+
+namespace {
+
+class TypeLocWriter : public TypeLocVisitor<TypeLocWriter> {
+  PCHWriter &Writer;
+  PCHWriter::RecordData &Record;
+
+public:
+  TypeLocWriter(PCHWriter &Writer, PCHWriter::RecordData &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::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);
+}
+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.getLParenLoc(), Record);
+  Writer.AddSourceLocation(TL.getRParenLoc(), Record);
+  for (unsigned i = 0, e = TL.getNumArgs(); i != e; ++i)
+    Writer.AddDeclRef(TL.getArg(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::VisitRecordTypeLoc(RecordTypeLoc TL) {
+  Writer.AddSourceLocation(TL.getNameLoc(), Record);
+}
+void TypeLocWriter::VisitEnumTypeLoc(EnumTypeLoc TL) {
+  Writer.AddSourceLocation(TL.getNameLoc(), Record);
+}
+void TypeLocWriter::VisitTemplateTypeParmTypeLoc(TemplateTypeParmTypeLoc TL) {
+  Writer.AddSourceLocation(TL.getNameLoc(), Record);
+}
+void TypeLocWriter::VisitSubstTemplateTypeParmTypeLoc(
+                                            SubstTemplateTypeParmTypeLoc TL) {
+  Writer.AddSourceLocation(TL.getNameLoc(), Record);
+}
+void TypeLocWriter::VisitTemplateSpecializationTypeLoc(
+                                           TemplateSpecializationTypeLoc TL) {
+  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::VisitElaboratedTypeLoc(ElaboratedTypeLoc TL) {
+  Writer.AddSourceLocation(TL.getKeywordLoc(), Record);
+  Writer.AddSourceRange(TL.getQualifierRange(), Record);
+}
+void TypeLocWriter::VisitInjectedClassNameTypeLoc(InjectedClassNameTypeLoc TL) {
+  Writer.AddSourceLocation(TL.getNameLoc(), Record);
+}
+void TypeLocWriter::VisitDependentNameTypeLoc(DependentNameTypeLoc TL) {
+  Writer.AddSourceLocation(TL.getKeywordLoc(), Record);
+  Writer.AddSourceRange(TL.getQualifierRange(), Record);
+  Writer.AddSourceLocation(TL.getNameLoc(), Record);
+}
+void TypeLocWriter::VisitDependentTemplateSpecializationTypeLoc(
+       DependentTemplateSpecializationTypeLoc TL) {
+  Writer.AddSourceLocation(TL.getKeywordLoc(), Record);
+  Writer.AddSourceRange(TL.getQualifierRange(), Record);
+  Writer.AddSourceLocation(TL.getNameLoc(), 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::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);
+}
+
+//===----------------------------------------------------------------------===//
+// PCHWriter Implementation
+//===----------------------------------------------------------------------===//
+
+static void EmitBlockID(unsigned ID, const char *Name,
+                        llvm::BitstreamWriter &Stream,
+                        PCHWriter::RecordData &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,
+                         PCHWriter::RecordData &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,
+                          PCHWriter::RecordData &Record) {
+#define RECORD(X) EmitRecordID(pch::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_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_ASM);
+  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_TYPES_COMPATIBLE);
+  RECORD(EXPR_CHOOSE);
+  RECORD(EXPR_GNU_NULL);
+  RECORD(EXPR_SHUFFLE_VECTOR);
+  RECORD(EXPR_BLOCK);
+  RECORD(EXPR_BLOCK_DECL_REF);
+  RECORD(EXPR_OBJC_STRING_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(EXPR_OBJC_SUPER_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_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_CXX_BOOL_LITERAL);
+  RECORD(EXPR_CXX_NULL_PTR_LITERAL);
+#undef RECORD
+}
+
+void PCHWriter::WriteBlockInfoBlock() {
+  RecordData Record;
+  Stream.EnterSubblock(llvm::bitc::BLOCKINFO_BLOCK_ID, 3);
+
+#define BLOCK(X) EmitBlockID(pch::X ## _ID, #X, Stream, Record)
+#define RECORD(X) EmitRecordID(pch::X, #X, Stream, Record)
+
+  // PCH Top-Level Block.
+  BLOCK(PCH_BLOCK);
+  RECORD(ORIGINAL_FILE_NAME);
+  RECORD(TYPE_OFFSET);
+  RECORD(DECL_OFFSET);
+  RECORD(LANGUAGE_OPTIONS);
+  RECORD(METADATA);
+  RECORD(IDENTIFIER_OFFSET);
+  RECORD(IDENTIFIER_TABLE);
+  RECORD(EXTERNAL_DEFINITIONS);
+  RECORD(SPECIAL_TYPES);
+  RECORD(STATISTICS);
+  RECORD(TENTATIVE_DEFINITIONS);
+  RECORD(UNUSED_FILESCOPED_DECLS);
+  RECORD(LOCALLY_SCOPED_EXTERNAL_DECLS);
+  RECORD(SELECTOR_OFFSETS);
+  RECORD(METHOD_POOL);
+  RECORD(PP_COUNTER_VALUE);
+  RECORD(SOURCE_LOCATION_OFFSETS);
+  RECORD(SOURCE_LOCATION_PRELOADS);
+  RECORD(STAT_CACHE);
+  RECORD(EXT_VECTOR_DECLS);
+  RECORD(VERSION_CONTROL_BRANCH_REVISION);
+  RECORD(MACRO_DEFINITION_OFFSETS);
+  RECORD(CHAINED_METADATA);
+  RECORD(REFERENCED_SELECTOR_POOL);
+  
+  // SourceManager Block.
+  BLOCK(SOURCE_MANAGER_BLOCK);
+  RECORD(SM_SLOC_FILE_ENTRY);
+  RECORD(SM_SLOC_BUFFER_ENTRY);
+  RECORD(SM_SLOC_BUFFER_BLOB);
+  RECORD(SM_SLOC_INSTANTIATION_ENTRY);
+  RECORD(SM_LINE_TABLE);
+
+  // Preprocessor Block.
+  BLOCK(PREPROCESSOR_BLOCK);
+  RECORD(PP_MACRO_OBJECT_LIKE);
+  RECORD(PP_MACRO_FUNCTION_LIKE);
+  RECORD(PP_TOKEN);
+  RECORD(PP_MACRO_INSTANTIATION);
+  RECORD(PP_MACRO_DEFINITION);
+  
+  // 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(DECL_ATTR);
+  RECORD(DECL_TRANSLATION_UNIT);
+  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_CLASS);
+  RECORD(DECL_OBJC_FORWARD_PROTOCOL);
+  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_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);
+  // Statements and Exprs can occur in the Decls and Types block.
+  AddStmtsExprs(Stream, Record);
+#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, const char *isysroot) {
+  assert(Filename && "No file name to adjust?");
+
+  if (!isysroot)
+    return Filename;
+
+  // Verify that the filename and the system root have the same prefix.
+  unsigned Pos = 0;
+  for (; Filename[Pos] && isysroot[Pos]; ++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 PCH metadata (e.g., i686-apple-darwin9).
+void PCHWriter::WriteMetadata(ASTContext &Context, const char *isysroot) {
+  using namespace llvm;
+
+  // Metadata
+  const TargetInfo &Target = Context.Target;
+  BitCodeAbbrev *MetaAbbrev = new BitCodeAbbrev();
+  MetaAbbrev->Add(BitCodeAbbrevOp(
+                    Chain ? pch::CHAINED_METADATA : pch::METADATA));
+  MetaAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // PCH major
+  MetaAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // PCH minor
+  MetaAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // Clang major
+  MetaAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // Clang minor
+  MetaAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Relocatable
+  // Target triple or chained PCH name
+  MetaAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
+  unsigned MetaAbbrevCode = Stream.EmitAbbrev(MetaAbbrev);
+
+  RecordData Record;
+  Record.push_back(Chain ? pch::CHAINED_METADATA : pch::METADATA);
+  Record.push_back(pch::VERSION_MAJOR);
+  Record.push_back(pch::VERSION_MINOR);
+  Record.push_back(CLANG_VERSION_MAJOR);
+  Record.push_back(CLANG_VERSION_MINOR);
+  Record.push_back(isysroot != 0);
+  // FIXME: This writes the absolute path for chained headers.
+  const std::string &BlobStr = Chain ? Chain->getFileName() : Target.getTriple().getTriple();
+  Stream.EmitRecordWithBlob(MetaAbbrevCode, Record, BlobStr);
+
+  // Original file name
+  SourceManager &SM = Context.getSourceManager();
+  if (const FileEntry *MainFile = SM.getFileEntryForID(SM.getMainFileID())) {
+    BitCodeAbbrev *FileAbbrev = new BitCodeAbbrev();
+    FileAbbrev->Add(BitCodeAbbrevOp(pch::ORIGINAL_FILE_NAME));
+    FileAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // File name
+    unsigned FileAbbrevCode = Stream.EmitAbbrev(FileAbbrev);
+
+    llvm::sys::Path MainFilePath(MainFile->getName());
+
+    MainFilePath.makeAbsolute();
+
+    const char *MainFileNameStr = MainFilePath.c_str();
+    MainFileNameStr = adjustFilenameForRelocatablePCH(MainFileNameStr,
+                                                      isysroot);
+    RecordData Record;
+    Record.push_back(pch::ORIGINAL_FILE_NAME);
+    Stream.EmitRecordWithBlob(FileAbbrevCode, Record, MainFileNameStr);
+  }
+
+  // Repository branch/version information.
+  BitCodeAbbrev *RepoAbbrev = new BitCodeAbbrev();
+  RepoAbbrev->Add(BitCodeAbbrevOp(pch::VERSION_CONTROL_BRANCH_REVISION));
+  RepoAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // SVN branch/tag
+  unsigned RepoAbbrevCode = Stream.EmitAbbrev(RepoAbbrev);
+  Record.clear();
+  Record.push_back(pch::VERSION_CONTROL_BRANCH_REVISION);
+  Stream.EmitRecordWithBlob(RepoAbbrevCode, Record,
+                            getClangFullRepositoryVersion());
+}
+
+/// \brief Write the LangOptions structure.
+void PCHWriter::WriteLanguageOptions(const LangOptions &LangOpts) {
+  RecordData Record;
+  Record.push_back(LangOpts.Trigraphs);
+  Record.push_back(LangOpts.BCPLComment);  // BCPL-style '//' comments.
+  Record.push_back(LangOpts.DollarIdents);  // '$' allowed in identifiers.
+  Record.push_back(LangOpts.AsmPreprocessor);  // Preprocessor in asm mode.
+  Record.push_back(LangOpts.GNUMode);  // True in gnu99 mode false in c99 mode (etc)
+  Record.push_back(LangOpts.GNUKeywords);  // Allow GNU-extension keywords
+  Record.push_back(LangOpts.ImplicitInt);  // C89 implicit 'int'.
+  Record.push_back(LangOpts.Digraphs);  // C94, C99 and C++
+  Record.push_back(LangOpts.HexFloats);  // C99 Hexadecimal float constants.
+  Record.push_back(LangOpts.C99);  // C99 Support
+  Record.push_back(LangOpts.Microsoft);  // Microsoft extensions.
+  Record.push_back(LangOpts.CPlusPlus);  // C++ Support
+  Record.push_back(LangOpts.CPlusPlus0x);  // C++0x Support
+  Record.push_back(LangOpts.CXXOperatorNames);  // Treat C++ operator names as keywords.
+
+  Record.push_back(LangOpts.ObjC1);  // Objective-C 1 support enabled.
+  Record.push_back(LangOpts.ObjC2);  // Objective-C 2 support enabled.
+  Record.push_back(LangOpts.ObjCNonFragileABI);  // Objective-C
+                                                 // modern abi enabled.
+  Record.push_back(LangOpts.ObjCNonFragileABI2); // Objective-C enhanced
+                                                 // modern abi enabled.
+  Record.push_back(LangOpts.NoConstantCFStrings); // non cfstring generation enabled..
+
+  Record.push_back(LangOpts.PascalStrings);  // Allow Pascal strings
+  Record.push_back(LangOpts.WritableStrings);  // Allow writable strings
+  Record.push_back(LangOpts.LaxVectorConversions);
+  Record.push_back(LangOpts.AltiVec);
+  Record.push_back(LangOpts.Exceptions);  // Support exception handling.
+  Record.push_back(LangOpts.SjLjExceptions);
+
+  Record.push_back(LangOpts.NeXTRuntime); // Use NeXT runtime.
+  Record.push_back(LangOpts.Freestanding); // Freestanding implementation
+  Record.push_back(LangOpts.NoBuiltin); // Do not use builtin functions (-fno-builtin)
+
+  // Whether static initializers are protected by locks.
+  Record.push_back(LangOpts.ThreadsafeStatics);
+  Record.push_back(LangOpts.POSIXThreads);
+  Record.push_back(LangOpts.Blocks); // block extension to C
+  Record.push_back(LangOpts.EmitAllDecls); // Emit all declarations, even if
+                                  // they are unused.
+  Record.push_back(LangOpts.MathErrno); // Math functions must respect errno
+                                  // (modulo the platform support).
+
+  Record.push_back(LangOpts.getSignedOverflowBehavior());
+  Record.push_back(LangOpts.HeinousExtensions);
+
+  Record.push_back(LangOpts.Optimize); // Whether __OPTIMIZE__ should be defined.
+  Record.push_back(LangOpts.OptimizeSize); // Whether __OPTIMIZE_SIZE__ should be
+                                  // defined.
+  Record.push_back(LangOpts.Static); // Should __STATIC__ be defined (as
+                                  // opposed to __DYNAMIC__).
+  Record.push_back(LangOpts.PICLevel); // The value for __PIC__, if non-zero.
+
+  Record.push_back(LangOpts.GNUInline); // Should GNU inline semantics be
+                                  // used (instead of C99 semantics).
+  Record.push_back(LangOpts.NoInline); // Should __NO_INLINE__ be defined.
+  Record.push_back(LangOpts.AccessControl); // Whether C++ access control should
+                                            // be enabled.
+  Record.push_back(LangOpts.CharIsSigned); // Whether char is a signed or
+                                           // unsigned type
+  Record.push_back(LangOpts.ShortWChar);  // force wchar_t to be unsigned short
+  Record.push_back(LangOpts.getGCMode());
+  Record.push_back(LangOpts.getVisibilityMode());
+  Record.push_back(LangOpts.getStackProtectorMode());
+  Record.push_back(LangOpts.InstantiationDepth);
+  Record.push_back(LangOpts.OpenCL);
+  Record.push_back(LangOpts.CatchUndefined);
+  Record.push_back(LangOpts.ElideConstructors);
+  Record.push_back(LangOpts.SpellChecking);
+  Stream.EmitRecord(pch::LANGUAGE_OPTIONS, Record);
+}
+
+//===----------------------------------------------------------------------===//
+// stat cache Serialization
+//===----------------------------------------------------------------------===//
+
+namespace {
+// Trait used for the on-disk hash table of stat cache results.
+class PCHStatCacheTrait {
+public:
+  typedef const char * key_type;
+  typedef key_type key_type_ref;
+
+  typedef std::pair<int, struct stat> data_type;
+  typedef const data_type& data_type_ref;
+
+  static unsigned ComputeHash(const char *path) {
+    return llvm::HashString(path);
+  }
+
+  std::pair<unsigned,unsigned>
+    EmitKeyDataLength(llvm::raw_ostream& Out, const char *path,
+                      data_type_ref Data) {
+    unsigned StrLen = strlen(path);
+    clang::io::Emit16(Out, StrLen);
+    unsigned DataLen = 1; // result value
+    if (Data.first == 0)
+      DataLen += 4 + 4 + 2 + 8 + 8;
+    clang::io::Emit8(Out, DataLen);
+    return std::make_pair(StrLen + 1, DataLen);
+  }
+
+  void EmitKey(llvm::raw_ostream& Out, const char *path, unsigned KeyLen) {
+    Out.write(path, KeyLen);
+  }
+
+  void EmitData(llvm::raw_ostream& Out, key_type_ref,
+                data_type_ref Data, unsigned DataLen) {
+    using namespace clang::io;
+    uint64_t Start = Out.tell(); (void)Start;
+
+    // Result of stat()
+    Emit8(Out, Data.first? 1 : 0);
+
+    if (Data.first == 0) {
+      Emit32(Out, (uint32_t) Data.second.st_ino);
+      Emit32(Out, (uint32_t) Data.second.st_dev);
+      Emit16(Out, (uint16_t) Data.second.st_mode);
+      Emit64(Out, (uint64_t) Data.second.st_mtime);
+      Emit64(Out, (uint64_t) Data.second.st_size);
+    }
+
+    assert(Out.tell() - Start == DataLen && "Wrong data length");
+  }
+};
+} // end anonymous namespace
+
+/// \brief Write the stat() system call cache to the PCH file.
+void PCHWriter::WriteStatCache(MemorizeStatCalls &StatCalls) {
+  // Build the on-disk hash table containing information about every
+  // stat() call.
+  OnDiskChainedHashTableGenerator<PCHStatCacheTrait> Generator;
+  unsigned NumStatEntries = 0;
+  for (MemorizeStatCalls::iterator Stat = StatCalls.begin(),
+                                StatEnd = StatCalls.end();
+       Stat != StatEnd; ++Stat, ++NumStatEntries) {
+    const char *Filename = Stat->first();
+    Generator.insert(Filename, Stat->second);
+  }
+
+  // Create the on-disk hash table in a buffer.
+  llvm::SmallString<4096> StatCacheData;
+  uint32_t BucketOffset;
+  {
+    llvm::raw_svector_ostream Out(StatCacheData);
+    // Make sure that no bucket is at offset 0
+    clang::io::Emit32(Out, 0);
+    BucketOffset = Generator.Emit(Out);
+  }
+
+  // Create a blob abbreviation
+  using namespace llvm;
+  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
+  Abbrev->Add(BitCodeAbbrevOp(pch::STAT_CACHE));
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
+  unsigned StatCacheAbbrev = Stream.EmitAbbrev(Abbrev);
+
+  // Write the stat cache
+  RecordData Record;
+  Record.push_back(pch::STAT_CACHE);
+  Record.push_back(BucketOffset);
+  Record.push_back(NumStatEntries);
+  Stream.EmitRecordWithBlob(StatCacheAbbrev, Record, StatCacheData.str());
+}
+
+//===----------------------------------------------------------------------===//
+// 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(pch::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, 12)); // Size
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 32)); // Modification time
+  // HeaderFileInfo fields.
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isImport
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2)); // DirInfo
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // NumIncludes
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // ControllingMacro
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // File name
+  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(pch::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(pch::SM_SLOC_BUFFER_BLOB));
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Blob
+  return Stream.EmitAbbrev(Abbrev);
+}
+
+/// \brief Create an abbreviation for the SLocEntry that refers to an
+/// buffer.
+static unsigned CreateSLocInstantiationAbbrev(llvm::BitstreamWriter &Stream) {
+  using namespace llvm;
+  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
+  Abbrev->Add(BitCodeAbbrevOp(pch::SM_SLOC_INSTANTIATION_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);
+}
+
+/// \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 PCHWriter::WriteSourceManagerBlock(SourceManager &SourceMgr,
+                                        const Preprocessor &PP,
+                                        const char *isysroot) {
+  RecordData Record;
+
+  // Enter the source manager block.
+  Stream.EnterSubblock(pch::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 SLocInstantiationAbbrv = CreateSLocInstantiationAbbrev(Stream);
+
+  // Write the line table.
+  if (SourceMgr.hasLineTable()) {
+    LineTableInfo &LineTable = SourceMgr.getLineTable();
+
+    // 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) {
+      // Emit the file ID
+      Record.push_back(L->first);
+
+      // 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(pch::SM_LINE_TABLE, Record);
+  }
+
+  // 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;
+  unsigned BaseSLocID = Chain ? Chain->getTotalNumSLocs() : 0;
+  SLocEntryOffsets.reserve(SourceMgr.sloc_entry_size() - 1 - BaseSLocID);
+  for (unsigned I = BaseSLocID + 1, N = SourceMgr.sloc_entry_size();
+       I != N; ++I) {
+    // Get this source location entry.
+    const SrcMgr::SLocEntry *SLoc = &SourceMgr.getSLocEntry(I);
+
+    // 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()) {
+      if (SLoc->getFile().getContentCache()->Entry)
+        Code = pch::SM_SLOC_FILE_ENTRY;
+      else
+        Code = pch::SM_SLOC_BUFFER_ENTRY;
+    } else
+      Code = pch::SM_SLOC_INSTANTIATION_ENTRY;
+    Record.clear();
+    Record.push_back(Code);
+
+    Record.push_back(SLoc->getOffset());
+    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->Entry) {
+        // The source location entry is a file. The blob associated
+        // with this entry is the file name.
+
+        // Emit size/modification time for this file.
+        Record.push_back(Content->Entry->getSize());
+        Record.push_back(Content->Entry->getModificationTime());
+
+        // Emit header-search information associated with this file.
+        HeaderFileInfo HFI;
+        HeaderSearch &HS = PP.getHeaderSearchInfo();
+        if (Content->Entry->getUID() < HS.header_file_size())
+          HFI = HS.header_file_begin()[Content->Entry->getUID()];
+        Record.push_back(HFI.isImport);
+        Record.push_back(HFI.DirInfo);
+        Record.push_back(HFI.NumIncludes);
+        AddIdentifierRef(HFI.ControllingMacro, Record);
+
+        // Turn the file name into an absolute path, if it isn't already.
+        const char *Filename = Content->Entry->getName();
+        llvm::sys::Path FilePath(Filename, strlen(Filename));
+        FilePath.makeAbsolute();
+        Filename = FilePath.c_str();
+
+        Filename = adjustFilenameForRelocatablePCH(Filename, isysroot);
+        Stream.EmitRecordWithBlob(SLocFileAbbrv, Record, Filename);
+
+        // FIXME: For now, preload all file source locations, so that
+        // we get the appropriate File entries in the reader. This is
+        // a temporary measure.
+        PreloadSLocs.push_back(BaseSLocID + SLocEntryOffsets.size());
+      } 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,
+                                  llvm::StringRef(Name, strlen(Name) + 1));
+        Record.clear();
+        Record.push_back(pch::SM_SLOC_BUFFER_BLOB);
+        Stream.EmitRecordWithBlob(SLocBufferBlobAbbrv, Record,
+                                  llvm::StringRef(Buffer->getBufferStart(),
+                                                  Buffer->getBufferSize() + 1));
+
+        if (strcmp(Name, "<built-in>") == 0)
+          PreloadSLocs.push_back(BaseSLocID + SLocEntryOffsets.size());
+      }
+    } else {
+      // The source location entry is an instantiation.
+      const SrcMgr::InstantiationInfo &Inst = SLoc->getInstantiation();
+      Record.push_back(Inst.getSpellingLoc().getRawEncoding());
+      Record.push_back(Inst.getInstantiationLocStart().getRawEncoding());
+      Record.push_back(Inst.getInstantiationLocEnd().getRawEncoding());
+
+      // Compute the token length for this macro expansion.
+      unsigned NextOffset = SourceMgr.getNextOffset();
+      if (I + 1 != N)
+        NextOffset = SourceMgr.getSLocEntry(I + 1).getOffset();
+      Record.push_back(NextOffset - SLoc->getOffset() - 1);
+      Stream.EmitRecordWithAbbrev(SLocInstantiationAbbrv, Record);
+    }
+  }
+
+  Stream.ExitBlock();
+
+  if (SLocEntryOffsets.empty())
+    return;
+
+  // Write the source-location offsets table into the PCH block. This
+  // table is used for lazily loading source-location information.
+  using namespace llvm;
+  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
+  Abbrev->Add(BitCodeAbbrevOp(pch::SOURCE_LOCATION_OFFSETS));
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 16)); // # of slocs
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 16)); // next offset
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // offsets
+  unsigned SLocOffsetsAbbrev = Stream.EmitAbbrev(Abbrev);
+
+  Record.clear();
+  Record.push_back(pch::SOURCE_LOCATION_OFFSETS);
+  Record.push_back(SLocEntryOffsets.size());
+  Record.push_back(SourceMgr.getNextOffset());
+  Stream.EmitRecordWithBlob(SLocOffsetsAbbrev, Record,
+                            (const char *)data(SLocEntryOffsets),
+                           SLocEntryOffsets.size()*sizeof(SLocEntryOffsets[0]));
+
+  // Write the source location entry preloads array, telling the PCH
+  // reader which source locations entries it should load eagerly.
+  Stream.EmitRecord(pch::SOURCE_LOCATION_PRELOADS, PreloadSLocs);
+}
+
+//===----------------------------------------------------------------------===//
+// Preprocessor Serialization
+//===----------------------------------------------------------------------===//
+
+/// \brief Writes the block containing the serialized form of the
+/// preprocessor.
+///
+void PCHWriter::WritePreprocessor(const Preprocessor &PP) {
+  RecordData Record;
+
+  // If the preprocessor __COUNTER__ value has been bumped, remember it.
+  if (PP.getCounterValue() != 0) {
+    Record.push_back(PP.getCounterValue());
+    Stream.EmitRecord(pch::PP_COUNTER_VALUE, Record);
+    Record.clear();
+  }
+
+  // Enter the preprocessor block.
+  Stream.EnterSubblock(pch::PREPROCESSOR_BLOCK_ID, 2);
+
+  // If the PCH 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 definitions that are live at the end of the file,
+  // emitting each to the PP section.
+  PreprocessingRecord *PPRec = PP.getPreprocessingRecord();
+  for (Preprocessor::macro_iterator I = PP.macro_begin(), E = PP.macro_end();
+       I != E; ++I) {
+    // FIXME: This emits macros in hash table order, we should do it in a stable
+    // order so that output is reproducible.
+    MacroInfo *MI = I->second;
+
+    // Don't emit builtin macros like __LINE__ to the PCH file unless they have
+    // been redefined by the header (in which case they are not isBuiltinMacro).
+    // Also skip macros from a PCH file if we're chaining.
+    if (MI->isBuiltinMacro() || (Chain && MI->isFromPCH()))
+      continue;
+
+    AddIdentifierRef(I->first, Record);
+    MacroOffsets[I->first] = Stream.GetCurrentBitNo();
+    Record.push_back(MI->getDefinitionLoc().getRawEncoding());
+    Record.push_back(MI->isUsed());
+
+    unsigned Code;
+    if (MI->isObjectLike()) {
+      Code = pch::PP_MACRO_OBJECT_LIKE;
+    } else {
+      Code = pch::PP_MACRO_FUNCTION_LIKE;
+
+      Record.push_back(MI->isC99Varargs());
+      Record.push_back(MI->isGNUVarargs());
+      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(getMacroDefinitionID(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);
+
+      Record.push_back(Tok.getLocation().getRawEncoding());
+      Record.push_back(Tok.getLength());
+
+      // FIXME: When reading literal tokens, reconstruct the literal pointer if
+      // it is needed.
+      AddIdentifierRef(Tok.getIdentifierInfo(), Record);
+
+      // FIXME: Should translate token kind to a stable encoding.
+      Record.push_back(Tok.getKind());
+      // FIXME: Should translate token flags to a stable encoding.
+      Record.push_back(Tok.getFlags());
+
+      Stream.EmitRecord(pch::PP_TOKEN, Record);
+      Record.clear();
+    }
+    ++NumMacros;
+  }
+  
+  // If the preprocessor has a preprocessing record, emit it.
+  unsigned NumPreprocessingRecords = 0;
+  if (PPRec) {
+    for (PreprocessingRecord::iterator E = PPRec->begin(), EEnd = PPRec->end();
+         E != EEnd; ++E) {
+      Record.clear();
+      
+      if (MacroInstantiation *MI = dyn_cast<MacroInstantiation>(*E)) {
+        Record.push_back(NumPreprocessingRecords++);
+        AddSourceLocation(MI->getSourceRange().getBegin(), Record);
+        AddSourceLocation(MI->getSourceRange().getEnd(), Record);
+        AddIdentifierRef(MI->getName(), Record);
+        Record.push_back(getMacroDefinitionID(MI->getDefinition()));
+        Stream.EmitRecord(pch::PP_MACRO_INSTANTIATION, Record);
+        continue;
+      }
+      
+      if (MacroDefinition *MD = dyn_cast<MacroDefinition>(*E)) {
+        // Record this macro definition's location.
+        pch::IdentID ID = getMacroDefinitionID(MD);
+        if (ID != MacroDefinitionOffsets.size()) {
+          if (ID > MacroDefinitionOffsets.size())
+            MacroDefinitionOffsets.resize(ID + 1);
+          
+          MacroDefinitionOffsets[ID] = Stream.GetCurrentBitNo();            
+        } else
+          MacroDefinitionOffsets.push_back(Stream.GetCurrentBitNo());
+        
+        Record.push_back(NumPreprocessingRecords++);
+        Record.push_back(ID);
+        AddSourceLocation(MD->getSourceRange().getBegin(), Record);
+        AddSourceLocation(MD->getSourceRange().getEnd(), Record);
+        AddIdentifierRef(MD->getName(), Record);
+        AddSourceLocation(MD->getLocation(), Record);
+        Stream.EmitRecord(pch::PP_MACRO_DEFINITION, Record);
+        continue;
+      }
+    }
+  }
+  
+  Stream.ExitBlock();
+  
+  // Write the offsets table for the preprocessing record.
+  if (NumPreprocessingRecords > 0) {
+    // Write the offsets table for identifier IDs.
+    using namespace llvm;
+    BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
+    Abbrev->Add(BitCodeAbbrevOp(pch::MACRO_DEFINITION_OFFSETS));
+    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // # of records
+    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // # of macro defs
+    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
+    unsigned MacroDefOffsetAbbrev = Stream.EmitAbbrev(Abbrev);
+    
+    Record.clear();
+    Record.push_back(pch::MACRO_DEFINITION_OFFSETS);
+    Record.push_back(NumPreprocessingRecords);
+    Record.push_back(MacroDefinitionOffsets.size());
+    Stream.EmitRecordWithBlob(MacroDefOffsetAbbrev, Record,
+                              (const char *)data(MacroDefinitionOffsets),
+                              MacroDefinitionOffsets.size() * sizeof(uint32_t));
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Type Serialization
+//===----------------------------------------------------------------------===//
+
+/// \brief Write the representation of a type to the PCH stream.
+void PCHWriter::WriteType(QualType T) {
+  pch::TypeID &ID = TypeIDs[T];
+  if (ID == 0) // we haven't seen this type before.
+    ID = NextTypeID++;
+
+  // Record the offset for this type.
+  unsigned Index = ID - 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.
+  PCHTypeWriter W(*this, Record);
+
+  if (T.hasLocalNonFastQualifiers()) {
+    Qualifiers Qs = T.getLocalQualifiers();
+    AddTypeRef(T.getLocalUnqualifiedType(), Record);
+    Record.push_back(Qs.getAsOpaqueValue());
+    W.Code = pch::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 PCHWriter::WriteDeclContextLexicalBlock(ASTContext &Context,
+                                                 DeclContext *DC) {
+  if (DC->decls_empty())
+    return 0;
+
+  uint64_t Offset = Stream.GetCurrentBitNo();
+  RecordData Record;
+  Record.push_back(pch::DECL_CONTEXT_LEXICAL);
+  llvm::SmallVector<pch::DeclID, 64> Decls;
+  for (DeclContext::decl_iterator D = DC->decls_begin(), DEnd = DC->decls_end();
+         D != DEnd; ++D)
+    Decls.push_back(GetDeclRef(*D));
+
+  ++NumLexicalDeclContexts;
+  Stream.EmitRecordWithBlob(DeclContextLexicalAbbrev, Record,
+     reinterpret_cast<char*>(Decls.data()), Decls.size() * sizeof(pch::DeclID));
+  return Offset;
+}
+
+/// \brief Write the block containing all of the declaration IDs
+/// visible from the given DeclContext.
+///
+/// \returns the offset of the DECL_CONTEXT_VISIBLE block within the
+/// bistream, or 0 if no block was written.
+uint64_t PCHWriter::WriteDeclContextVisibleBlock(ASTContext &Context,
+                                                 DeclContext *DC) {
+  if (DC->getPrimaryContext() != DC)
+    return 0;
+
+  // Since there is no name lookup into functions or methods, don't bother to
+  // build a visible-declarations table for these entities.
+  if (DC->isFunctionOrMethod())
+    return 0;
+
+  // If not in C++, we perform name lookup for the translation unit via the
+  // IdentifierInfo chains, don't bother to build a visible-declarations table.
+  // FIXME: In C++ we need the visible declarations in order to "see" the
+  // friend declarations, is there a way to do this without writing the table ?
+  if (DC->isTranslationUnit() && !Context.getLangOptions().CPlusPlus)
+    return 0;
+
+  // Force the DeclContext to build a its name-lookup table.
+  DC->lookup(DeclarationName());
+
+  // Serialize the contents of the mapping used for lookup. Note that,
+  // although we have two very different code paths, the serialized
+  // representation is the same for both cases: a declaration name,
+  // followed by a size, followed by references to the visible
+  // declarations that have that name.
+  uint64_t Offset = Stream.GetCurrentBitNo();
+  RecordData Record;
+  StoredDeclsMap *Map = static_cast<StoredDeclsMap*>(DC->getLookupPtr());
+  if (!Map)
+    return 0;
+
+  for (StoredDeclsMap::iterator D = Map->begin(), DEnd = Map->end();
+       D != DEnd; ++D) {
+    AddDeclarationName(D->first, Record);
+    DeclContext::lookup_result Result = D->second.getLookupResult(Context);
+    Record.push_back(Result.second - Result.first);
+    for (; Result.first != Result.second; ++Result.first)
+      AddDeclRef(*Result.first, Record);
+  }
+
+  if (Record.size() == 0)
+    return 0;
+
+  Stream.EmitRecord(pch::DECL_CONTEXT_VISIBLE, Record);
+  ++NumVisibleDeclContexts;
+  return Offset;
+}
+
+void PCHWriter::WriteTypeDeclOffsets() {
+  using namespace llvm;
+  RecordData Record;
+
+  // Write the type offsets array
+  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
+  Abbrev->Add(BitCodeAbbrevOp(pch::TYPE_OFFSET));
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // # of types
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // types block
+  unsigned TypeOffsetAbbrev = Stream.EmitAbbrev(Abbrev);
+  Record.clear();
+  Record.push_back(pch::TYPE_OFFSET);
+  Record.push_back(TypeOffsets.size());
+  Stream.EmitRecordWithBlob(TypeOffsetAbbrev, Record,
+                            (const char *)data(TypeOffsets),
+                            TypeOffsets.size() * sizeof(TypeOffsets[0]));
+
+  // Write the declaration offsets array
+  Abbrev = new BitCodeAbbrev();
+  Abbrev->Add(BitCodeAbbrevOp(pch::DECL_OFFSET));
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // # of declarations
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // declarations block
+  unsigned DeclOffsetAbbrev = Stream.EmitAbbrev(Abbrev);
+  Record.clear();
+  Record.push_back(pch::DECL_OFFSET);
+  Record.push_back(DeclOffsets.size());
+  Stream.EmitRecordWithBlob(DeclOffsetAbbrev, Record,
+                            (const char *)data(DeclOffsets),
+                            DeclOffsets.size() * sizeof(DeclOffsets[0]));
+}
+
+//===----------------------------------------------------------------------===//
+// Global Method Pool and Selector Serialization
+//===----------------------------------------------------------------------===//
+
+namespace {
+// Trait used for the on-disk hash table used in the method pool.
+class PCHMethodPoolTrait {
+  PCHWriter &Writer;
+
+public:
+  typedef Selector key_type;
+  typedef key_type key_type_ref;
+
+  struct data_type {
+    pch::SelectorID ID;
+    ObjCMethodList Instance, Factory;
+  };
+  typedef const data_type& data_type_ref;
+
+  explicit PCHMethodPoolTrait(PCHWriter &Writer) : Writer(Writer) { }
+
+  static unsigned ComputeHash(Selector Sel) {
+    unsigned N = Sel.getNumArgs();
+    if (N == 0)
+      ++N;
+    unsigned R = 5381;
+    for (unsigned I = 0; I != N; ++I)
+      if (IdentifierInfo *II = Sel.getIdentifierInfoForSlot(I))
+        R = llvm::HashString(II->getName(), R);
+    return R;
+  }
+
+  std::pair<unsigned,unsigned>
+    EmitKeyDataLength(llvm::raw_ostream& Out, Selector Sel,
+                      data_type_ref Methods) {
+    unsigned KeyLen = 2 + (Sel.getNumArgs()? Sel.getNumArgs() * 4 : 4);
+    clang::io::Emit16(Out, KeyLen);
+    unsigned DataLen = 4 + 2 + 2; // 2 bytes for each of the method counts
+    for (const ObjCMethodList *Method = &Methods.Instance; Method;
+         Method = Method->Next)
+      if (Method->Method)
+        DataLen += 4;
+    for (const ObjCMethodList *Method = &Methods.Factory; Method;
+         Method = Method->Next)
+      if (Method->Method)
+        DataLen += 4;
+    clang::io::Emit16(Out, DataLen);
+    return std::make_pair(KeyLen, DataLen);
+  }
+
+  void EmitKey(llvm::raw_ostream& Out, Selector Sel, unsigned) {
+    uint64_t Start = Out.tell();
+    assert((Start >> 32) == 0 && "Selector key offset too large");
+    Writer.SetSelectorOffset(Sel, Start);
+    unsigned N = Sel.getNumArgs();
+    clang::io::Emit16(Out, N);
+    if (N == 0)
+      N = 1;
+    for (unsigned I = 0; I != N; ++I)
+      clang::io::Emit32(Out,
+                    Writer.getIdentifierRef(Sel.getIdentifierInfoForSlot(I)));
+  }
+
+  void EmitData(llvm::raw_ostream& Out, key_type_ref,
+                data_type_ref Methods, unsigned DataLen) {
+    uint64_t Start = Out.tell(); (void)Start;
+    clang::io::Emit32(Out, Methods.ID);
+    unsigned NumInstanceMethods = 0;
+    for (const ObjCMethodList *Method = &Methods.Instance; Method;
+         Method = Method->Next)
+      if (Method->Method)
+        ++NumInstanceMethods;
+
+    unsigned NumFactoryMethods = 0;
+    for (const ObjCMethodList *Method = &Methods.Factory; Method;
+         Method = Method->Next)
+      if (Method->Method)
+        ++NumFactoryMethods;
+
+    clang::io::Emit16(Out, NumInstanceMethods);
+    clang::io::Emit16(Out, NumFactoryMethods);
+    for (const ObjCMethodList *Method = &Methods.Instance; Method;
+         Method = Method->Next)
+      if (Method->Method)
+        clang::io::Emit32(Out, Writer.getDeclID(Method->Method));
+    for (const ObjCMethodList *Method = &Methods.Factory; Method;
+         Method = Method->Next)
+      if (Method->Method)
+        clang::io::Emit32(Out, Writer.getDeclID(Method->Method));
+
+    assert(Out.tell() - Start == DataLen && "Data length is wrong");
+  }
+};
+} // end anonymous namespace
+
+/// \brief Write ObjC data: selectors and the method pool.
+///
+/// The method pool contains both instance and factory methods, stored
+/// in an on-disk hash table indexed by the selector. The hash table also
+/// contains an empty entry for every other selector known to Sema.
+void PCHWriter::WriteSelectors(Sema &SemaRef) {
+  using namespace llvm;
+
+  // Do we have to do anything at all?
+  if (SemaRef.MethodPool.empty() && SelectorIDs.empty())
+    return;
+  unsigned NumTableEntries = 0;
+  // Create and write out the blob that contains selectors and the method pool.
+  {
+    OnDiskChainedHashTableGenerator<PCHMethodPoolTrait> Generator;
+
+    // Create the on-disk hash table representation. We walk through every
+    // selector we've seen and look it up in the method pool.
+    SelectorOffsets.resize(NextSelectorID - FirstSelectorID);
+    for (llvm::DenseMap<Selector, pch::SelectorID>::iterator
+             I = SelectorIDs.begin(), E = SelectorIDs.end();
+         I != E; ++I) {
+      Selector S = I->first;
+      Sema::GlobalMethodPool::iterator F = SemaRef.MethodPool.find(S);
+      PCHMethodPoolTrait::data_type Data = {
+        I->second,
+        ObjCMethodList(),
+        ObjCMethodList()
+      };
+      if (F != SemaRef.MethodPool.end()) {
+        Data.Instance = F->second.first;
+        Data.Factory = F->second.second;
+      }
+      // Only write this selector if it's not in an existing PCH or something
+      // changed.
+      if (Chain && I->second < FirstSelectorID) {
+        // Selector already exists. Did it change?
+        bool changed = false;
+        for (ObjCMethodList *M = &Data.Instance; !changed && M && M->Method;
+             M = M->Next) {
+          if (M->Method->getPCHLevel() == 0)
+            changed = true;
+        }
+        for (ObjCMethodList *M = &Data.Factory; !changed && M && M->Method;
+             M = M->Next) {
+          if (M->Method->getPCHLevel() == 0)
+            changed = true;
+        }
+        if (!changed)
+          continue;
+      } else if (Data.Instance.Method || Data.Factory.Method) {
+        // A new method pool entry.
+        ++NumTableEntries;
+      }
+      Generator.insert(S, Data);
+    }
+
+    // Create the on-disk hash table in a buffer.
+    llvm::SmallString<4096> MethodPool;
+    uint32_t BucketOffset;
+    {
+      PCHMethodPoolTrait Trait(*this);
+      llvm::raw_svector_ostream Out(MethodPool);
+      // Make sure that no bucket is at offset 0
+      clang::io::Emit32(Out, 0);
+      BucketOffset = Generator.Emit(Out, Trait);
+    }
+
+    // Create a blob abbreviation
+    BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
+    Abbrev->Add(BitCodeAbbrevOp(pch::METHOD_POOL));
+    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
+    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
+    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
+    unsigned MethodPoolAbbrev = Stream.EmitAbbrev(Abbrev);
+
+    // Write the method pool
+    RecordData Record;
+    Record.push_back(pch::METHOD_POOL);
+    Record.push_back(BucketOffset);
+    Record.push_back(NumTableEntries);
+    Stream.EmitRecordWithBlob(MethodPoolAbbrev, Record, MethodPool.str());
+
+    // Create a blob abbreviation for the selector table offsets.
+    Abbrev = new BitCodeAbbrev();
+    Abbrev->Add(BitCodeAbbrevOp(pch::SELECTOR_OFFSETS));
+    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // index
+    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
+    unsigned SelectorOffsetAbbrev = Stream.EmitAbbrev(Abbrev);
+
+    // Write the selector offsets table.
+    Record.clear();
+    Record.push_back(pch::SELECTOR_OFFSETS);
+    Record.push_back(SelectorOffsets.size());
+    Stream.EmitRecordWithBlob(SelectorOffsetAbbrev, Record,
+                              (const char *)data(SelectorOffsets),
+                              SelectorOffsets.size() * 4);
+  }
+}
+
+/// \brief Write the selectors referenced in @selector expression into PCH file.
+void PCHWriter::WriteReferencedSelectorsPool(Sema &SemaRef) {
+  using namespace llvm;
+  if (SemaRef.ReferencedSelectors.empty())
+    return;
+
+  RecordData Record;
+
+  // Note: this writes out all references even for a dependent PCH. But it is
+  // very tricky to fix, and given that @selector shouldn't really appear in
+  // headers, probably not worth it. It's not a correctness issue.
+  for (DenseMap<Selector, SourceLocation>::iterator S =
+       SemaRef.ReferencedSelectors.begin(),
+       E = SemaRef.ReferencedSelectors.end(); S != E; ++S) {
+    Selector Sel = (*S).first;
+    SourceLocation Loc = (*S).second;
+    AddSelectorRef(Sel, Record);
+    AddSourceLocation(Loc, Record);
+  }
+  Stream.EmitRecord(pch::REFERENCED_SELECTOR_POOL, Record);
+}
+
+//===----------------------------------------------------------------------===//
+// Identifier Table Serialization
+//===----------------------------------------------------------------------===//
+
+namespace {
+class PCHIdentifierTableTrait {
+  PCHWriter &Writer;
+  Preprocessor &PP;
+
+  /// \brief Determines whether this is an "interesting" identifier
+  /// that needs a full IdentifierInfo structure written into the hash
+  /// table.
+  static bool isInterestingIdentifier(const IdentifierInfo *II) {
+    return II->isPoisoned() ||
+      II->isExtensionToken() ||
+      II->hasMacroDefinition() ||
+      II->getObjCOrBuiltinID() ||
+      II->getFETokenInfo<void>();
+  }
+
+public:
+  typedef const IdentifierInfo* key_type;
+  typedef key_type  key_type_ref;
+
+  typedef pch::IdentID data_type;
+  typedef data_type data_type_ref;
+
+  PCHIdentifierTableTrait(PCHWriter &Writer, Preprocessor &PP)
+    : Writer(Writer), PP(PP) { }
+
+  static unsigned ComputeHash(const IdentifierInfo* II) {
+    return llvm::HashString(II->getName());
+  }
+
+  std::pair<unsigned,unsigned>
+    EmitKeyDataLength(llvm::raw_ostream& Out, const IdentifierInfo* II,
+                      pch::IdentID ID) {
+    unsigned KeyLen = II->getLength() + 1;
+    unsigned DataLen = 4; // 4 bytes for the persistent ID << 1
+    if (isInterestingIdentifier(II)) {
+      DataLen += 2; // 2 bytes for builtin ID, flags
+      if (II->hasMacroDefinition() &&
+          !PP.getMacroInfo(const_cast<IdentifierInfo *>(II))->isBuiltinMacro())
+        DataLen += 4;
+      for (IdentifierResolver::iterator D = IdentifierResolver::begin(II),
+                                     DEnd = IdentifierResolver::end();
+           D != DEnd; ++D)
+        DataLen += sizeof(pch::DeclID);
+    }
+    clang::io::Emit16(Out, DataLen);
+    // We emit the key length after the data length so that every
+    // string is preceded by a 16-bit length. This matches the PTH
+    // format for storing identifiers.
+    clang::io::Emit16(Out, KeyLen);
+    return std::make_pair(KeyLen, DataLen);
+  }
+
+  void EmitKey(llvm::raw_ostream& Out, const IdentifierInfo* II,
+               unsigned KeyLen) {
+    // Record the location of the key data.  This is used when generating
+    // the mapping from persistent IDs to strings.
+    Writer.SetIdentifierOffset(II, Out.tell());
+    Out.write(II->getNameStart(), KeyLen);
+  }
+
+  void EmitData(llvm::raw_ostream& Out, const IdentifierInfo* II,
+                pch::IdentID ID, unsigned) {
+    if (!isInterestingIdentifier(II)) {
+      clang::io::Emit32(Out, ID << 1);
+      return;
+    }
+
+    clang::io::Emit32(Out, (ID << 1) | 0x01);
+    uint32_t Bits = 0;
+    bool hasMacroDefinition =
+      II->hasMacroDefinition() &&
+      !PP.getMacroInfo(const_cast<IdentifierInfo *>(II))->isBuiltinMacro();
+    Bits = (uint32_t)II->getObjCOrBuiltinID();
+    Bits = (Bits << 1) | unsigned(hasMacroDefinition);
+    Bits = (Bits << 1) | unsigned(II->isExtensionToken());
+    Bits = (Bits << 1) | unsigned(II->isPoisoned());
+    Bits = (Bits << 1) | unsigned(II->hasRevertedTokenIDToIdentifier());
+    Bits = (Bits << 1) | unsigned(II->isCPlusPlusOperatorKeyword());
+    clang::io::Emit16(Out, Bits);
+
+    if (hasMacroDefinition)
+      clang::io::Emit32(Out, Writer.getMacroOffset(II));
+
+    // Emit the declaration IDs in reverse order, because the
+    // IdentifierResolver provides the declarations as they would be
+    // visible (e.g., the function "stat" would come before the struct
+    // "stat"), but IdentifierResolver::AddDeclToIdentifierChain()
+    // adds declarations to the end of the list (so we need to see the
+    // struct "status" before the function "status").
+    // Only emit declarations that aren't from a chained PCH, though.
+    llvm::SmallVector<Decl *, 16> Decls(IdentifierResolver::begin(II),
+                                        IdentifierResolver::end());
+    for (llvm::SmallVector<Decl *, 16>::reverse_iterator D = Decls.rbegin(),
+                                                      DEnd = Decls.rend();
+         D != DEnd; ++D)
+      clang::io::Emit32(Out, Writer.getDeclID(*D));
+  }
+};
+} // end anonymous namespace
+
+/// \brief Write the identifier table into the PCH file.
+///
+/// The identifier table consists of a blob containing string data
+/// (the actual identifiers themselves) and a separate "offsets" index
+/// that maps identifier IDs to locations within the blob.
+void PCHWriter::WriteIdentifierTable(Preprocessor &PP) {
+  using namespace llvm;
+
+  // Create and write out the blob that contains the identifier
+  // strings.
+  {
+    OnDiskChainedHashTableGenerator<PCHIdentifierTableTrait> Generator;
+
+    // Look for any identifiers that were named while processing the
+    // headers, but are otherwise not needed. We add these to the hash
+    // table to enable checking of the predefines buffer in the case
+    // where the user adds new macro definitions when building the PCH
+    // file.
+    for (IdentifierTable::iterator ID = PP.getIdentifierTable().begin(),
+                                IDEnd = PP.getIdentifierTable().end();
+         ID != IDEnd; ++ID)
+      getIdentifierRef(ID->second);
+
+    // Create the on-disk hash table representation. We only store offsets
+    // for identifiers that appear here for the first time.
+    IdentifierOffsets.resize(NextIdentID - FirstIdentID);
+    for (llvm::DenseMap<const IdentifierInfo *, pch::IdentID>::iterator
+           ID = IdentifierIDs.begin(), IDEnd = IdentifierIDs.end();
+         ID != IDEnd; ++ID) {
+      assert(ID->first && "NULL identifier in identifier table");
+      if (!Chain || !ID->first->isFromPCH())
+        Generator.insert(ID->first, ID->second);
+    }
+
+    // Create the on-disk hash table in a buffer.
+    llvm::SmallString<4096> IdentifierTable;
+    uint32_t BucketOffset;
+    {
+      PCHIdentifierTableTrait Trait(*this, PP);
+      llvm::raw_svector_ostream Out(IdentifierTable);
+      // Make sure that no bucket is at offset 0
+      clang::io::Emit32(Out, 0);
+      BucketOffset = Generator.Emit(Out, Trait);
+    }
+
+    // Create a blob abbreviation
+    BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
+    Abbrev->Add(BitCodeAbbrevOp(pch::IDENTIFIER_TABLE));
+    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
+    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
+    unsigned IDTableAbbrev = Stream.EmitAbbrev(Abbrev);
+
+    // Write the identifier table
+    RecordData Record;
+    Record.push_back(pch::IDENTIFIER_TABLE);
+    Record.push_back(BucketOffset);
+    Stream.EmitRecordWithBlob(IDTableAbbrev, Record, IdentifierTable.str());
+  }
+
+  // Write the offsets table for identifier IDs.
+  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
+  Abbrev->Add(BitCodeAbbrevOp(pch::IDENTIFIER_OFFSET));
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // # of identifiers
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
+  unsigned IdentifierOffsetAbbrev = Stream.EmitAbbrev(Abbrev);
+
+  RecordData Record;
+  Record.push_back(pch::IDENTIFIER_OFFSET);
+  Record.push_back(IdentifierOffsets.size());
+  Stream.EmitRecordWithBlob(IdentifierOffsetAbbrev, Record,
+                            (const char *)data(IdentifierOffsets),
+                            IdentifierOffsets.size() * sizeof(uint32_t));
+}
+
+//===----------------------------------------------------------------------===//
+// General Serialization Routines
+//===----------------------------------------------------------------------===//
+
+/// \brief Write a record containing the given attributes.
+void PCHWriter::WriteAttributeRecord(const Attr *Attr) {
+  RecordData Record;
+  for (; Attr; Attr = Attr->getNext()) {
+    Record.push_back(Attr->getKind()); // FIXME: stable encoding, target attrs
+    Record.push_back(Attr->isInherited());
+    switch (Attr->getKind()) {
+    default:
+      assert(0 && "Does not support PCH writing for this attribute yet!");
+      break;
+    case attr::Alias:
+      AddString(cast<AliasAttr>(Attr)->getAliasee(), Record);
+      break;
+
+    case attr::AlignMac68k:
+      break;
+
+    case attr::Aligned:
+      Record.push_back(cast<AlignedAttr>(Attr)->getAlignment());
+      break;
+
+    case attr::AlwaysInline:
+      break;
+
+    case attr::AnalyzerNoReturn:
+      break;
+
+    case attr::Annotate:
+      AddString(cast<AnnotateAttr>(Attr)->getAnnotation(), Record);
+      break;
+
+    case attr::AsmLabel:
+      AddString(cast<AsmLabelAttr>(Attr)->getLabel(), Record);
+      break;
+
+    case attr::BaseCheck:
+      break;
+
+    case attr::Blocks:
+      Record.push_back(cast<BlocksAttr>(Attr)->getType()); // FIXME: stable
+      break;
+
+    case attr::CDecl:
+      break;
+
+    case attr::Cleanup:
+      AddDeclRef(cast<CleanupAttr>(Attr)->getFunctionDecl(), Record);
+      break;
+
+    case attr::Const:
+      break;
+
+    case attr::Constructor:
+      Record.push_back(cast<ConstructorAttr>(Attr)->getPriority());
+      break;
+
+    case attr::DLLExport:
+    case attr::DLLImport:
+    case attr::Deprecated:
+      break;
+
+    case attr::Destructor:
+      Record.push_back(cast<DestructorAttr>(Attr)->getPriority());
+      break;
+
+    case attr::FastCall:
+    case attr::Final:
+      break;
+
+    case attr::Format: {
+      const FormatAttr *Format = cast<FormatAttr>(Attr);
+      AddString(Format->getType(), Record);
+      Record.push_back(Format->getFormatIdx());
+      Record.push_back(Format->getFirstArg());
+      break;
+    }
+
+    case attr::FormatArg: {
+      const FormatArgAttr *Format = cast<FormatArgAttr>(Attr);
+      Record.push_back(Format->getFormatIdx());
+      break;
+    }
+
+    case attr::Sentinel : {
+      const SentinelAttr *Sentinel = cast<SentinelAttr>(Attr);
+      Record.push_back(Sentinel->getSentinel());
+      Record.push_back(Sentinel->getNullPos());
+      break;
+    }
+
+    case attr::GNUInline:
+    case attr::Hiding:
+    case attr::IBAction:
+    case attr::IBOutlet:
+    case attr::Malloc:
+    case attr::NoDebug:
+    case attr::NoInline:
+    case attr::NoReturn:
+    case attr::NoThrow:
+      break;
+
+    case attr::IBOutletCollection: {
+      const IBOutletCollectionAttr *ICA = cast<IBOutletCollectionAttr>(Attr);
+      AddTypeRef(ICA->getType(), Record);
+      break;
+    }
+
+    case attr::NonNull: {
+      const NonNullAttr *NonNull = cast<NonNullAttr>(Attr);
+      Record.push_back(NonNull->size());
+      Record.insert(Record.end(), NonNull->begin(), NonNull->end());
+      break;
+    }
+
+    case attr::CFReturnsNotRetained:
+    case attr::CFReturnsRetained:
+    case attr::NSReturnsNotRetained:
+    case attr::NSReturnsRetained:
+    case attr::ObjCException:
+    case attr::ObjCNSObject:
+    case attr::Overloadable:
+    case attr::Override:
+      break;
+
+    case attr::MaxFieldAlignment:
+      Record.push_back(cast<MaxFieldAlignmentAttr>(Attr)->getAlignment());
+      break;
+
+    case attr::Packed:
+      break;
+
+    case attr::Pure:
+      break;
+
+    case attr::Regparm:
+      Record.push_back(cast<RegparmAttr>(Attr)->getNumParams());
+      break;
+
+    case attr::ReqdWorkGroupSize:
+      Record.push_back(cast<ReqdWorkGroupSizeAttr>(Attr)->getXDim());
+      Record.push_back(cast<ReqdWorkGroupSizeAttr>(Attr)->getYDim());
+      Record.push_back(cast<ReqdWorkGroupSizeAttr>(Attr)->getZDim());
+      break;
+
+    case attr::Section:
+      AddString(cast<SectionAttr>(Attr)->getName(), Record);
+      break;
+
+    case attr::StdCall:
+    case attr::TransparentUnion:
+    case attr::Unavailable:
+    case attr::Unused:
+    case attr::Used:
+      break;
+
+    case attr::Visibility:
+      // FIXME: stable encoding
+      Record.push_back(cast<VisibilityAttr>(Attr)->getVisibility());
+      Record.push_back(cast<VisibilityAttr>(Attr)->isFromPragma());
+      break;
+
+    case attr::WarnUnusedResult:
+    case attr::Weak:
+    case attr::WeakRef:
+    case attr::WeakImport:
+      break;
+    }
+  }
+
+  Stream.EmitRecord(pch::DECL_ATTR, Record);
+}
+
+void PCHWriter::AddString(const std::string &Str, RecordData &Record) {
+  Record.push_back(Str.size());
+  Record.insert(Record.end(), Str.begin(), Str.end());
+}
+
+/// \brief Note that the identifier II occurs at the given offset
+/// within the identifier table.
+void PCHWriter::SetIdentifierOffset(const IdentifierInfo *II, uint32_t Offset) {
+  pch::IdentID ID = IdentifierIDs[II];
+  // Only store offsets new to this PCH file. Other identifier names are looked
+  // up earlier in the chain and thus don't need an offset.
+  if (ID >= FirstIdentID)
+    IdentifierOffsets[ID - FirstIdentID] = Offset;
+}
+
+/// \brief Note that the selector Sel occurs at the given offset
+/// within the method pool/selector table.
+void PCHWriter::SetSelectorOffset(Selector Sel, uint32_t Offset) {
+  unsigned ID = SelectorIDs[Sel];
+  assert(ID && "Unknown selector");
+  // Don't record offsets for selectors that are also available in a different
+  // file.
+  if (ID < FirstSelectorID)
+    return;
+  SelectorOffsets[ID - FirstSelectorID] = Offset;
+}
+
+PCHWriter::PCHWriter(llvm::BitstreamWriter &Stream)
+  : Stream(Stream), Chain(0), FirstDeclID(1), NextDeclID(FirstDeclID),
+    FirstTypeID(pch::NUM_PREDEF_TYPE_IDS), NextTypeID(FirstTypeID),
+    FirstIdentID(1), NextIdentID(FirstIdentID), FirstSelectorID(1),
+    NextSelectorID(FirstSelectorID), CollectedStmts(&StmtsToEmit),
+    NumStatements(0), NumMacros(0), NumLexicalDeclContexts(0),
+    NumVisibleDeclContexts(0) {
+}
+
+void PCHWriter::WritePCH(Sema &SemaRef, MemorizeStatCalls *StatCalls,
+                         const char *isysroot) {
+  // Emit the file header.
+  Stream.Emit((unsigned)'C', 8);
+  Stream.Emit((unsigned)'P', 8);
+  Stream.Emit((unsigned)'C', 8);
+  Stream.Emit((unsigned)'H', 8);
+
+  WriteBlockInfoBlock();
+
+  if (Chain)
+    WritePCHChain(SemaRef, StatCalls, isysroot);
+  else
+    WritePCHCore(SemaRef, StatCalls, isysroot);
+}
+
+void PCHWriter::WritePCHCore(Sema &SemaRef, MemorizeStatCalls *StatCalls,
+                             const char *isysroot) {
+  using namespace llvm;
+
+  ASTContext &Context = SemaRef.Context;
+  Preprocessor &PP = SemaRef.PP;
+
+  // The translation unit is the first declaration we'll emit.
+  DeclIDs[Context.getTranslationUnitDecl()] = 1;
+  ++NextDeclID;
+  DeclTypesToEmit.push(Context.getTranslationUnitDecl());
+
+  // Make sure that we emit IdentifierInfos (and any attached
+  // declarations) for builtins.
+  {
+    IdentifierTable &Table = PP.getIdentifierTable();
+    llvm::SmallVector<const char *, 32> BuiltinNames;
+    Context.BuiltinInfo.GetBuiltinNames(BuiltinNames,
+                                        Context.getLangOptions().NoBuiltin);
+    for (unsigned I = 0, N = BuiltinNames.size(); I != N; ++I)
+      getIdentifierRef(&Table.get(BuiltinNames[I]));
+  }
+
+  // Build a record containing all of the tentative definitions in this file, in
+  // TentativeDefinitions order.  Generally, this record will be empty for
+  // headers.
+  RecordData TentativeDefinitions;
+  for (unsigned i = 0, e = SemaRef.TentativeDefinitions.size(); i != e; ++i) {
+    AddDeclRef(SemaRef.TentativeDefinitions[i], TentativeDefinitions);
+  }
+
+  // Build a record containing all of the file scoped decls in this file.
+  RecordData UnusedFileScopedDecls;
+  for (unsigned i=0, e = SemaRef.UnusedFileScopedDecls.size(); i !=e; ++i)
+    AddDeclRef(SemaRef.UnusedFileScopedDecls[i], UnusedFileScopedDecls);
+
+  RecordData WeakUndeclaredIdentifiers;
+  if (!SemaRef.WeakUndeclaredIdentifiers.empty()) {
+    WeakUndeclaredIdentifiers.push_back(
+                                      SemaRef.WeakUndeclaredIdentifiers.size());
+    for (llvm::DenseMap<IdentifierInfo*,Sema::WeakInfo>::iterator
+         I = SemaRef.WeakUndeclaredIdentifiers.begin(),
+         E = SemaRef.WeakUndeclaredIdentifiers.end(); I != E; ++I) {
+      AddIdentifierRef(I->first, WeakUndeclaredIdentifiers);
+      AddIdentifierRef(I->second.getAlias(), WeakUndeclaredIdentifiers);
+      AddSourceLocation(I->second.getLocation(), WeakUndeclaredIdentifiers);
+      WeakUndeclaredIdentifiers.push_back(I->second.getUsed());
+    }
+  }
+
+  // Build a record containing all of the locally-scoped external
+  // declarations in this header file. Generally, this record will be
+  // empty.
+  RecordData LocallyScopedExternalDecls;
+  // FIXME: This is filling in the PCH file in densemap order which is
+  // nondeterminstic!
+  for (llvm::DenseMap<DeclarationName, NamedDecl *>::iterator
+         TD = SemaRef.LocallyScopedExternalDecls.begin(),
+         TDEnd = SemaRef.LocallyScopedExternalDecls.end();
+       TD != TDEnd; ++TD)
+    AddDeclRef(TD->second, LocallyScopedExternalDecls);
+
+  // Build a record containing all of the ext_vector declarations.
+  RecordData ExtVectorDecls;
+  for (unsigned I = 0, N = SemaRef.ExtVectorDecls.size(); I != N; ++I)
+    AddDeclRef(SemaRef.ExtVectorDecls[I], ExtVectorDecls);
+
+  // Build a record containing all of the VTable uses information.
+  RecordData VTableUses;
+  if (!SemaRef.VTableUses.empty()) {
+    VTableUses.push_back(SemaRef.VTableUses.size());
+    for (unsigned I = 0, N = SemaRef.VTableUses.size(); I != N; ++I) {
+      AddDeclRef(SemaRef.VTableUses[I].first, VTableUses);
+      AddSourceLocation(SemaRef.VTableUses[I].second, VTableUses);
+      VTableUses.push_back(SemaRef.VTablesUsed[SemaRef.VTableUses[I].first]);
+    }
+  }
+
+  // Build a record containing all of dynamic classes declarations.
+  RecordData DynamicClasses;
+  for (unsigned I = 0, N = SemaRef.DynamicClasses.size(); I != N; ++I)
+    AddDeclRef(SemaRef.DynamicClasses[I], DynamicClasses);
+
+  // Build a record containing all of pending implicit instantiations.
+  RecordData PendingImplicitInstantiations;
+  for (std::deque<Sema::PendingImplicitInstantiation>::iterator
+         I = SemaRef.PendingImplicitInstantiations.begin(),
+         N = SemaRef.PendingImplicitInstantiations.end(); I != N; ++I) {
+    AddDeclRef(I->first, PendingImplicitInstantiations);
+    AddSourceLocation(I->second, PendingImplicitInstantiations);
+  }
+  assert(SemaRef.PendingLocalImplicitInstantiations.empty() &&
+         "There are local ones at end of translation unit!");
+
+  // Build a record containing some declaration references.
+  RecordData SemaDeclRefs;
+  if (SemaRef.StdNamespace || SemaRef.StdBadAlloc) {
+    AddDeclRef(SemaRef.getStdNamespace(), SemaDeclRefs);
+    AddDeclRef(SemaRef.getStdBadAlloc(), SemaDeclRefs);
+  }
+
+  // Write the remaining PCH contents.
+  RecordData Record;
+  Stream.EnterSubblock(pch::PCH_BLOCK_ID, 5);
+  WriteMetadata(Context, isysroot);
+  WriteLanguageOptions(Context.getLangOptions());
+  if (StatCalls && !isysroot)
+    WriteStatCache(*StatCalls);
+  WriteSourceManagerBlock(Context.getSourceManager(), PP, isysroot);
+  // Write the record of special types.
+  Record.clear();
+
+  AddTypeRef(Context.getBuiltinVaListType(), Record);
+  AddTypeRef(Context.getObjCIdType(), Record);
+  AddTypeRef(Context.getObjCSelType(), Record);
+  AddTypeRef(Context.getObjCProtoType(), Record);
+  AddTypeRef(Context.getObjCClassType(), Record);
+  AddTypeRef(Context.getRawCFConstantStringType(), Record);
+  AddTypeRef(Context.getRawObjCFastEnumerationStateType(), Record);
+  AddTypeRef(Context.getFILEType(), Record);
+  AddTypeRef(Context.getjmp_bufType(), Record);
+  AddTypeRef(Context.getsigjmp_bufType(), Record);
+  AddTypeRef(Context.ObjCIdRedefinitionType, Record);
+  AddTypeRef(Context.ObjCClassRedefinitionType, Record);
+  AddTypeRef(Context.getRawBlockdescriptorType(), Record);
+  AddTypeRef(Context.getRawBlockdescriptorExtendedType(), Record);
+  AddTypeRef(Context.ObjCSelRedefinitionType, Record);
+  AddTypeRef(Context.getRawNSConstantStringType(), Record);
+  Record.push_back(Context.isInt128Installed());
+  Stream.EmitRecord(pch::SPECIAL_TYPES, Record);
+
+  // Keep writing types and declarations until all types and
+  // declarations have been written.
+  Stream.EnterSubblock(pch::DECLTYPES_BLOCK_ID, 3);
+  WriteDeclsBlockAbbrevs();
+  while (!DeclTypesToEmit.empty()) {
+    DeclOrType DOT = DeclTypesToEmit.front();
+    DeclTypesToEmit.pop();
+    if (DOT.isType())
+      WriteType(DOT.getType());
+    else
+      WriteDecl(Context, DOT.getDecl());
+  }
+  Stream.ExitBlock();
+
+  WritePreprocessor(PP);
+  WriteSelectors(SemaRef);
+  WriteReferencedSelectorsPool(SemaRef);
+  WriteIdentifierTable(PP);
+
+  WriteTypeDeclOffsets();
+
+  // Write the record containing external, unnamed definitions.
+  if (!ExternalDefinitions.empty())
+    Stream.EmitRecord(pch::EXTERNAL_DEFINITIONS, ExternalDefinitions);
+
+  // Write the record containing tentative definitions.
+  if (!TentativeDefinitions.empty())
+    Stream.EmitRecord(pch::TENTATIVE_DEFINITIONS, TentativeDefinitions);
+
+  // Write the record containing unused file scoped decls.
+  if (!UnusedFileScopedDecls.empty())
+    Stream.EmitRecord(pch::UNUSED_FILESCOPED_DECLS, UnusedFileScopedDecls);
+
+  // Write the record containing weak undeclared identifiers.
+  if (!WeakUndeclaredIdentifiers.empty())
+    Stream.EmitRecord(pch::WEAK_UNDECLARED_IDENTIFIERS,
+                      WeakUndeclaredIdentifiers);
+
+  // Write the record containing locally-scoped external definitions.
+  if (!LocallyScopedExternalDecls.empty())
+    Stream.EmitRecord(pch::LOCALLY_SCOPED_EXTERNAL_DECLS,
+                      LocallyScopedExternalDecls);
+
+  // Write the record containing ext_vector type names.
+  if (!ExtVectorDecls.empty())
+    Stream.EmitRecord(pch::EXT_VECTOR_DECLS, ExtVectorDecls);
+
+  // Write the record containing VTable uses information.
+  if (!VTableUses.empty())
+    Stream.EmitRecord(pch::VTABLE_USES, VTableUses);
+
+  // Write the record containing dynamic classes declarations.
+  if (!DynamicClasses.empty())
+    Stream.EmitRecord(pch::DYNAMIC_CLASSES, DynamicClasses);
+
+  // Write the record containing pending implicit instantiations.
+  if (!PendingImplicitInstantiations.empty())
+    Stream.EmitRecord(pch::PENDING_IMPLICIT_INSTANTIATIONS,
+                      PendingImplicitInstantiations);
+
+  // Write the record containing declaration references of Sema.
+  if (!SemaDeclRefs.empty())
+    Stream.EmitRecord(pch::SEMA_DECL_REFS, SemaDeclRefs);
+
+  // Some simple statistics
+  Record.clear();
+  Record.push_back(NumStatements);
+  Record.push_back(NumMacros);
+  Record.push_back(NumLexicalDeclContexts);
+  Record.push_back(NumVisibleDeclContexts);
+  Stream.EmitRecord(pch::STATISTICS, Record);
+  Stream.ExitBlock();
+}
+
+void PCHWriter::WritePCHChain(Sema &SemaRef, MemorizeStatCalls *StatCalls,
+                              const char *isysroot) {
+  using namespace llvm;
+
+  FirstDeclID += Chain->getTotalNumDecls();
+  FirstTypeID += Chain->getTotalNumTypes();
+  FirstIdentID += Chain->getTotalNumIdentifiers();
+  FirstSelectorID += Chain->getTotalNumSelectors();
+  NextDeclID = FirstDeclID;
+  NextTypeID = FirstTypeID;
+  NextIdentID = FirstIdentID;
+  NextSelectorID = FirstSelectorID;
+
+  ASTContext &Context = SemaRef.Context;
+  Preprocessor &PP = SemaRef.PP;
+
+  RecordData Record;
+  Stream.EnterSubblock(pch::PCH_BLOCK_ID, 5);
+  WriteMetadata(Context, isysroot);
+  if (StatCalls && !isysroot)
+    WriteStatCache(*StatCalls);
+  // FIXME: Source manager block should only write new stuff, which could be
+  // done by tracking the largest ID in the chain
+  WriteSourceManagerBlock(Context.getSourceManager(), PP, isysroot);
+
+  // The special types are in the chained PCH.
+
+  // We don't start with the translation unit, but with its decls that
+  // don't come from the other PCH.
+  const TranslationUnitDecl *TU = Context.getTranslationUnitDecl();
+  llvm::SmallVector<pch::DeclID, 64> NewGlobalDecls;
+  for (DeclContext::decl_iterator I = TU->noload_decls_begin(),
+                                  E = TU->noload_decls_end();
+       I != E; ++I) {
+    if ((*I)->getPCHLevel() == 0)
+      NewGlobalDecls.push_back(GetDeclRef(*I));
+    else if ((*I)->isChangedSinceDeserialization())
+      (void)GetDeclRef(*I); // Make sure it's written, but don't record it.
+  }
+  // We also need to write a lexical updates block for the TU.
+  llvm::BitCodeAbbrev *Abv = new llvm::BitCodeAbbrev();
+  Abv->Add(llvm::BitCodeAbbrevOp(pch::TU_UPDATE_LEXICAL));
+  Abv->Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::Blob));
+  unsigned TuUpdateLexicalAbbrev = Stream.EmitAbbrev(Abv);
+  Record.clear();
+  Record.push_back(pch::TU_UPDATE_LEXICAL);
+  Stream.EmitRecordWithBlob(TuUpdateLexicalAbbrev, Record,
+                          reinterpret_cast<const char*>(NewGlobalDecls.data()),
+                          NewGlobalDecls.size() * sizeof(pch::DeclID));
+
+  // Build a record containing all of the new tentative definitions in this
+  // file, in TentativeDefinitions order.
+  RecordData TentativeDefinitions;
+  for (unsigned i = 0, e = SemaRef.TentativeDefinitions.size(); i != e; ++i) {
+    if (SemaRef.TentativeDefinitions[i]->getPCHLevel() == 0)
+      AddDeclRef(SemaRef.TentativeDefinitions[i], TentativeDefinitions);
+  }
+
+  // Build a record containing all of the file scoped decls in this file.
+  RecordData UnusedFileScopedDecls;
+  for (unsigned i=0, e = SemaRef.UnusedFileScopedDecls.size(); i !=e; ++i) {
+    if (SemaRef.UnusedFileScopedDecls[i]->getPCHLevel() == 0)
+      AddDeclRef(SemaRef.UnusedFileScopedDecls[i], UnusedFileScopedDecls);
+  }
+
+  // We write the entire table, overwriting the tables from the chain.
+  RecordData WeakUndeclaredIdentifiers;
+  if (!SemaRef.WeakUndeclaredIdentifiers.empty()) {
+    WeakUndeclaredIdentifiers.push_back(
+                                      SemaRef.WeakUndeclaredIdentifiers.size());
+    for (llvm::DenseMap<IdentifierInfo*,Sema::WeakInfo>::iterator
+         I = SemaRef.WeakUndeclaredIdentifiers.begin(),
+         E = SemaRef.WeakUndeclaredIdentifiers.end(); I != E; ++I) {
+      AddIdentifierRef(I->first, WeakUndeclaredIdentifiers);
+      AddIdentifierRef(I->second.getAlias(), WeakUndeclaredIdentifiers);
+      AddSourceLocation(I->second.getLocation(), WeakUndeclaredIdentifiers);
+      WeakUndeclaredIdentifiers.push_back(I->second.getUsed());
+    }
+  }
+
+  // Build a record containing all of the locally-scoped external
+  // declarations in this header file. Generally, this record will be
+  // empty.
+  RecordData LocallyScopedExternalDecls;
+  // FIXME: This is filling in the PCH file in densemap order which is
+  // nondeterminstic!
+  for (llvm::DenseMap<DeclarationName, NamedDecl *>::iterator
+         TD = SemaRef.LocallyScopedExternalDecls.begin(),
+         TDEnd = SemaRef.LocallyScopedExternalDecls.end();
+       TD != TDEnd; ++TD) {
+    if (TD->second->getPCHLevel() == 0)
+      AddDeclRef(TD->second, LocallyScopedExternalDecls);
+  }
+
+  // Build a record containing all of the ext_vector declarations.
+  RecordData ExtVectorDecls;
+  for (unsigned I = 0, N = SemaRef.ExtVectorDecls.size(); I != N; ++I) {
+    if (SemaRef.ExtVectorDecls[I]->getPCHLevel() == 0)
+      AddDeclRef(SemaRef.ExtVectorDecls[I], ExtVectorDecls);
+  }
+
+  // Build a record containing all of the VTable uses information.
+  // We write everything here, because it's too hard to determine whether
+  // a use is new to this part.
+  RecordData VTableUses;
+  if (!SemaRef.VTableUses.empty()) {
+    VTableUses.push_back(SemaRef.VTableUses.size());
+    for (unsigned I = 0, N = SemaRef.VTableUses.size(); I != N; ++I) {
+      AddDeclRef(SemaRef.VTableUses[I].first, VTableUses);
+      AddSourceLocation(SemaRef.VTableUses[I].second, VTableUses);
+      VTableUses.push_back(SemaRef.VTablesUsed[SemaRef.VTableUses[I].first]);
+    }
+  }
+
+  // Build a record containing all of dynamic classes declarations.
+  RecordData DynamicClasses;
+  for (unsigned I = 0, N = SemaRef.DynamicClasses.size(); I != N; ++I)
+    if (SemaRef.DynamicClasses[I]->getPCHLevel() == 0)
+      AddDeclRef(SemaRef.DynamicClasses[I], DynamicClasses);
+
+  // Build a record containing all of pending implicit instantiations.
+  RecordData PendingImplicitInstantiations;
+  for (std::deque<Sema::PendingImplicitInstantiation>::iterator
+         I = SemaRef.PendingImplicitInstantiations.begin(),
+         N = SemaRef.PendingImplicitInstantiations.end(); I != N; ++I) {
+    if (I->first->getPCHLevel() == 0) {
+      AddDeclRef(I->first, PendingImplicitInstantiations);
+      AddSourceLocation(I->second, PendingImplicitInstantiations);
+    }
+  }
+  assert(SemaRef.PendingLocalImplicitInstantiations.empty() &&
+         "There are local ones at end of translation unit!");
+
+  // Build a record containing some declaration references.
+  // It's not worth the effort to avoid duplication here.
+  RecordData SemaDeclRefs;
+  if (SemaRef.StdNamespace || SemaRef.StdBadAlloc) {
+    AddDeclRef(SemaRef.getStdNamespace(), SemaDeclRefs);
+    AddDeclRef(SemaRef.getStdBadAlloc(), SemaDeclRefs);
+  }
+
+  Stream.EnterSubblock(pch::DECLTYPES_BLOCK_ID, 3);
+  WriteDeclsBlockAbbrevs();
+  while (!DeclTypesToEmit.empty()) {
+    DeclOrType DOT = DeclTypesToEmit.front();
+    DeclTypesToEmit.pop();
+    if (DOT.isType())
+      WriteType(DOT.getType());
+    else
+      WriteDecl(Context, DOT.getDecl());
+  }
+  Stream.ExitBlock();
+
+  WritePreprocessor(PP);
+  WriteSelectors(SemaRef);
+  WriteReferencedSelectorsPool(SemaRef);
+  WriteIdentifierTable(PP);
+  WriteTypeDeclOffsets();
+
+  /// Build a record containing first declarations from a chained PCH and the
+  /// most recent declarations in this PCH that they point to.
+  RecordData FirstLatestDeclIDs;
+  for (FirstLatestDeclMap::iterator
+        I = FirstLatestDecls.begin(), E = FirstLatestDecls.end(); I != E; ++I) {
+    assert(I->first->getPCHLevel() > I->second->getPCHLevel() &&
+           "Expected first & second to be in different PCHs");
+    AddDeclRef(I->first, FirstLatestDeclIDs);
+    AddDeclRef(I->second, FirstLatestDeclIDs);
+  }
+  if (!FirstLatestDeclIDs.empty())
+    Stream.EmitRecord(pch::REDECLS_UPDATE_LATEST, FirstLatestDeclIDs);
+
+  // Write the record containing external, unnamed definitions.
+  if (!ExternalDefinitions.empty())
+    Stream.EmitRecord(pch::EXTERNAL_DEFINITIONS, ExternalDefinitions);
+
+  // Write the record containing tentative definitions.
+  if (!TentativeDefinitions.empty())
+    Stream.EmitRecord(pch::TENTATIVE_DEFINITIONS, TentativeDefinitions);
+
+  // Write the record containing unused file scoped decls.
+  if (!UnusedFileScopedDecls.empty())
+    Stream.EmitRecord(pch::UNUSED_FILESCOPED_DECLS, UnusedFileScopedDecls);
+
+  // Write the record containing weak undeclared identifiers.
+  if (!WeakUndeclaredIdentifiers.empty())
+    Stream.EmitRecord(pch::WEAK_UNDECLARED_IDENTIFIERS,
+                      WeakUndeclaredIdentifiers);
+
+  // Write the record containing locally-scoped external definitions.
+  if (!LocallyScopedExternalDecls.empty())
+    Stream.EmitRecord(pch::LOCALLY_SCOPED_EXTERNAL_DECLS,
+                      LocallyScopedExternalDecls);
+
+  // Write the record containing ext_vector type names.
+  if (!ExtVectorDecls.empty())
+    Stream.EmitRecord(pch::EXT_VECTOR_DECLS, ExtVectorDecls);
+
+  // Write the record containing VTable uses information.
+  if (!VTableUses.empty())
+    Stream.EmitRecord(pch::VTABLE_USES, VTableUses);
+
+  // Write the record containing dynamic classes declarations.
+  if (!DynamicClasses.empty())
+    Stream.EmitRecord(pch::DYNAMIC_CLASSES, DynamicClasses);
+
+  // Write the record containing pending implicit instantiations.
+  if (!PendingImplicitInstantiations.empty())
+    Stream.EmitRecord(pch::PENDING_IMPLICIT_INSTANTIATIONS,
+                      PendingImplicitInstantiations);
+
+  // Write the record containing declaration references of Sema.
+  if (!SemaDeclRefs.empty())
+    Stream.EmitRecord(pch::SEMA_DECL_REFS, SemaDeclRefs);
+
+  Record.clear();
+  Record.push_back(NumStatements);
+  Record.push_back(NumMacros);
+  Record.push_back(NumLexicalDeclContexts);
+  Record.push_back(NumVisibleDeclContexts);
+  WriteDeclUpdateBlock();
+  Stream.EmitRecord(pch::STATISTICS, Record);
+  Stream.ExitBlock();
+}
+
+void PCHWriter::WriteDeclUpdateBlock() {
+  if (ReplacedDecls.empty())
+    return;
+
+  RecordData Record;
+  for (llvm::SmallVector<std::pair<pch::DeclID, uint64_t>, 16>::iterator
+           I = ReplacedDecls.begin(), E = ReplacedDecls.end(); I != E; ++I) {
+    Record.push_back(I->first);
+    Record.push_back(I->second);
+  }
+  Stream.EmitRecord(pch::DECL_REPLACEMENTS, Record);
+}
+
+void PCHWriter::AddSourceLocation(SourceLocation Loc, RecordData &Record) {
+  Record.push_back(Loc.getRawEncoding());
+}
+
+void PCHWriter::AddSourceRange(SourceRange Range, RecordData &Record) {
+  AddSourceLocation(Range.getBegin(), Record);
+  AddSourceLocation(Range.getEnd(), Record);
+}
+
+void PCHWriter::AddAPInt(const llvm::APInt &Value, RecordData &Record) {
+  Record.push_back(Value.getBitWidth());
+  unsigned N = Value.getNumWords();
+  const uint64_t* Words = Value.getRawData();
+  for (unsigned I = 0; I != N; ++I)
+    Record.push_back(Words[I]);
+}
+
+void PCHWriter::AddAPSInt(const llvm::APSInt &Value, RecordData &Record) {
+  Record.push_back(Value.isUnsigned());
+  AddAPInt(Value, Record);
+}
+
+void PCHWriter::AddAPFloat(const llvm::APFloat &Value, RecordData &Record) {
+  AddAPInt(Value.bitcastToAPInt(), Record);
+}
+
+void PCHWriter::AddIdentifierRef(const IdentifierInfo *II, RecordData &Record) {
+  Record.push_back(getIdentifierRef(II));
+}
+
+pch::IdentID PCHWriter::getIdentifierRef(const IdentifierInfo *II) {
+  if (II == 0)
+    return 0;
+
+  pch::IdentID &ID = IdentifierIDs[II];
+  if (ID == 0)
+    ID = NextIdentID++;
+  return ID;
+}
+
+pch::IdentID PCHWriter::getMacroDefinitionID(MacroDefinition *MD) {
+  if (MD == 0)
+    return 0;
+  
+  pch::IdentID &ID = MacroDefinitions[MD];
+  if (ID == 0)
+    ID = MacroDefinitions.size();
+  return ID;
+}
+
+void PCHWriter::AddSelectorRef(const Selector SelRef, RecordData &Record) {
+  Record.push_back(getSelectorRef(SelRef));
+}
+
+pch::SelectorID PCHWriter::getSelectorRef(Selector Sel) {
+  if (Sel.getAsOpaquePtr() == 0) {
+    return 0;
+  }
+
+  pch::SelectorID &SID = SelectorIDs[Sel];
+  if (SID == 0 && Chain) {
+    // This might trigger a ReadSelector callback, which will set the ID for
+    // this selector.
+    Chain->LoadSelector(Sel);
+  }
+  if (SID == 0) {
+    SID = NextSelectorID++;
+  }
+  return SID;
+}
+
+void PCHWriter::AddCXXTemporary(const CXXTemporary *Temp, RecordData &Record) {
+  AddDeclRef(Temp->getDestructor(), Record);
+}
+
+void PCHWriter::AddTemplateArgumentLocInfo(TemplateArgument::ArgKind Kind,
+                                           const TemplateArgumentLocInfo &Arg,
+                                           RecordData &Record) {
+  switch (Kind) {
+  case TemplateArgument::Expression:
+    AddStmt(Arg.getAsExpr());
+    break;
+  case TemplateArgument::Type:
+    AddTypeSourceInfo(Arg.getAsTypeSourceInfo(), Record);
+    break;
+  case TemplateArgument::Template:
+    AddSourceRange(Arg.getTemplateQualifierRange(), Record);
+    AddSourceLocation(Arg.getTemplateNameLoc(), Record);
+    break;
+  case TemplateArgument::Null:
+  case TemplateArgument::Integral:
+  case TemplateArgument::Declaration:
+  case TemplateArgument::Pack:
+    break;
+  }
+}
+
+void PCHWriter::AddTemplateArgumentLoc(const TemplateArgumentLoc &Arg,
+                                       RecordData &Record) {
+  AddTemplateArgument(Arg.getArgument(), Record);
+
+  if (Arg.getArgument().getKind() == TemplateArgument::Expression) {
+    bool InfoHasSameExpr
+      = Arg.getArgument().getAsExpr() == Arg.getLocInfo().getAsExpr();
+    Record.push_back(InfoHasSameExpr);
+    if (InfoHasSameExpr)
+      return; // Avoid storing the same expr twice.
+  }
+  AddTemplateArgumentLocInfo(Arg.getArgument().getKind(), Arg.getLocInfo(),
+                             Record);
+}
+
+void PCHWriter::AddTypeSourceInfo(TypeSourceInfo *TInfo, RecordData &Record) {
+  if (TInfo == 0) {
+    AddTypeRef(QualType(), Record);
+    return;
+  }
+
+  AddTypeRef(TInfo->getType(), Record);
+  TypeLocWriter TLW(*this, Record);
+  for (TypeLoc TL = TInfo->getTypeLoc(); !TL.isNull(); TL = TL.getNextTypeLoc())
+    TLW.Visit(TL);
+}
+
+void PCHWriter::AddTypeRef(QualType T, RecordData &Record) {
+  if (T.isNull()) {
+    Record.push_back(pch::PREDEF_TYPE_NULL_ID);
+    return;
+  }
+
+  unsigned FastQuals = T.getLocalFastQualifiers();
+  T.removeFastQualifiers();
+
+  if (T.hasLocalNonFastQualifiers()) {
+    pch::TypeID &ID = TypeIDs[T];
+    if (ID == 0) {
+      // We haven't seen these qualifiers applied to this type before.
+      // Assign it a new ID.  This is the only time we enqueue a
+      // qualified type, and it has no CV qualifiers.
+      ID = NextTypeID++;
+      DeclTypesToEmit.push(T);
+    }
+
+    // Encode the type qualifiers in the type reference.
+    Record.push_back((ID << Qualifiers::FastWidth) | FastQuals);
+    return;
+  }
+
+  assert(!T.hasLocalQualifiers());
+
+  if (const BuiltinType *BT = dyn_cast<BuiltinType>(T.getTypePtr())) {
+    pch::TypeID ID = 0;
+    switch (BT->getKind()) {
+    case BuiltinType::Void:       ID = pch::PREDEF_TYPE_VOID_ID;       break;
+    case BuiltinType::Bool:       ID = pch::PREDEF_TYPE_BOOL_ID;       break;
+    case BuiltinType::Char_U:     ID = pch::PREDEF_TYPE_CHAR_U_ID;     break;
+    case BuiltinType::UChar:      ID = pch::PREDEF_TYPE_UCHAR_ID;      break;
+    case BuiltinType::UShort:     ID = pch::PREDEF_TYPE_USHORT_ID;     break;
+    case BuiltinType::UInt:       ID = pch::PREDEF_TYPE_UINT_ID;       break;
+    case BuiltinType::ULong:      ID = pch::PREDEF_TYPE_ULONG_ID;      break;
+    case BuiltinType::ULongLong:  ID = pch::PREDEF_TYPE_ULONGLONG_ID;  break;
+    case BuiltinType::UInt128:    ID = pch::PREDEF_TYPE_UINT128_ID;    break;
+    case BuiltinType::Char_S:     ID = pch::PREDEF_TYPE_CHAR_S_ID;     break;
+    case BuiltinType::SChar:      ID = pch::PREDEF_TYPE_SCHAR_ID;      break;
+    case BuiltinType::WChar:      ID = pch::PREDEF_TYPE_WCHAR_ID;      break;
+    case BuiltinType::Short:      ID = pch::PREDEF_TYPE_SHORT_ID;      break;
+    case BuiltinType::Int:        ID = pch::PREDEF_TYPE_INT_ID;        break;
+    case BuiltinType::Long:       ID = pch::PREDEF_TYPE_LONG_ID;       break;
+    case BuiltinType::LongLong:   ID = pch::PREDEF_TYPE_LONGLONG_ID;   break;
+    case BuiltinType::Int128:     ID = pch::PREDEF_TYPE_INT128_ID;     break;
+    case BuiltinType::Float:      ID = pch::PREDEF_TYPE_FLOAT_ID;      break;
+    case BuiltinType::Double:     ID = pch::PREDEF_TYPE_DOUBLE_ID;     break;
+    case BuiltinType::LongDouble: ID = pch::PREDEF_TYPE_LONGDOUBLE_ID; break;
+    case BuiltinType::NullPtr:    ID = pch::PREDEF_TYPE_NULLPTR_ID;    break;
+    case BuiltinType::Char16:     ID = pch::PREDEF_TYPE_CHAR16_ID;     break;
+    case BuiltinType::Char32:     ID = pch::PREDEF_TYPE_CHAR32_ID;     break;
+    case BuiltinType::Overload:   ID = pch::PREDEF_TYPE_OVERLOAD_ID;   break;
+    case BuiltinType::Dependent:  ID = pch::PREDEF_TYPE_DEPENDENT_ID;  break;
+    case BuiltinType::ObjCId:     ID = pch::PREDEF_TYPE_OBJC_ID;       break;
+    case BuiltinType::ObjCClass:  ID = pch::PREDEF_TYPE_OBJC_CLASS;    break;
+    case BuiltinType::ObjCSel:    ID = pch::PREDEF_TYPE_OBJC_SEL;      break;
+    case BuiltinType::UndeducedAuto:
+      assert(0 && "Should not see undeduced auto here");
+      break;
+    }
+
+    Record.push_back((ID << Qualifiers::FastWidth) | FastQuals);
+    return;
+  }
+
+  pch::TypeID &ID = TypeIDs[T];
+  if (ID == 0) {
+    // We haven't seen this type before. Assign it a new ID and put it
+    // into the queue of types to emit.
+    ID = NextTypeID++;
+    DeclTypesToEmit.push(T);
+  }
+
+  // Encode the type qualifiers in the type reference.
+  Record.push_back((ID << Qualifiers::FastWidth) | FastQuals);
+}
+
+void PCHWriter::AddDeclRef(const Decl *D, RecordData &Record) {
+  Record.push_back(GetDeclRef(D));
+}
+
+pch::DeclID PCHWriter::GetDeclRef(const Decl *D) {
+  if (D == 0) {
+    return 0;
+  }
+
+  pch::DeclID &ID = DeclIDs[D];
+  if (ID == 0) {
+    // We haven't seen this declaration before. Give it a new ID and
+    // enqueue it in the list of declarations to emit.
+    ID = NextDeclID++;
+    DeclTypesToEmit.push(const_cast<Decl *>(D));
+  } else if (ID < FirstDeclID && D->isChangedSinceDeserialization()) {
+    // We don't add it to the replacement collection here, because we don't
+    // have the offset yet.
+    DeclTypesToEmit.push(const_cast<Decl *>(D));
+    // Reset the flag, so that we don't add this decl multiple times.
+    const_cast<Decl *>(D)->setChangedSinceDeserialization(false);
+  }
+
+  return ID;
+}
+
+pch::DeclID PCHWriter::getDeclID(const Decl *D) {
+  if (D == 0)
+    return 0;
+
+  assert(DeclIDs.find(D) != DeclIDs.end() && "Declaration not emitted!");
+  return DeclIDs[D];
+}
+
+void PCHWriter::AddDeclarationName(DeclarationName Name, RecordData &Record) {
+  // FIXME: Emit a stable enum for NameKind.  0 = Identifier etc.
+  Record.push_back(Name.getNameKind());
+  switch (Name.getNameKind()) {
+  case DeclarationName::Identifier:
+    AddIdentifierRef(Name.getAsIdentifierInfo(), Record);
+    break;
+
+  case DeclarationName::ObjCZeroArgSelector:
+  case DeclarationName::ObjCOneArgSelector:
+  case DeclarationName::ObjCMultiArgSelector:
+    AddSelectorRef(Name.getObjCSelector(), Record);
+    break;
+
+  case DeclarationName::CXXConstructorName:
+  case DeclarationName::CXXDestructorName:
+  case DeclarationName::CXXConversionFunctionName:
+    AddTypeRef(Name.getCXXNameType(), Record);
+    break;
+
+  case DeclarationName::CXXOperatorName:
+    Record.push_back(Name.getCXXOverloadedOperator());
+    break;
+
+  case DeclarationName::CXXLiteralOperatorName:
+    AddIdentifierRef(Name.getCXXLiteralIdentifier(), Record);
+    break;
+
+  case DeclarationName::CXXUsingDirective:
+    // No extra data to emit
+    break;
+  }
+}
+
+void PCHWriter::AddNestedNameSpecifier(NestedNameSpecifier *NNS,
+                                       RecordData &Record) {
+  // Nested name specifiers usually aren't too long. I think that 8 would
+  // typically accomodate the vast majority.
+  llvm::SmallVector<NestedNameSpecifier *, 8> NestedNames;
+
+  // Push each of the NNS's onto a stack for serialization in reverse order.
+  while (NNS) {
+    NestedNames.push_back(NNS);
+    NNS = NNS->getPrefix();
+  }
+
+  Record.push_back(NestedNames.size());
+  while(!NestedNames.empty()) {
+    NNS = NestedNames.pop_back_val();
+    NestedNameSpecifier::SpecifierKind Kind = NNS->getKind();
+    Record.push_back(Kind);
+    switch (Kind) {
+    case NestedNameSpecifier::Identifier:
+      AddIdentifierRef(NNS->getAsIdentifier(), Record);
+      break;
+
+    case NestedNameSpecifier::Namespace:
+      AddDeclRef(NNS->getAsNamespace(), Record);
+      break;
+
+    case NestedNameSpecifier::TypeSpec:
+    case NestedNameSpecifier::TypeSpecWithTemplate:
+      AddTypeRef(QualType(NNS->getAsType(), 0), Record);
+      Record.push_back(Kind == NestedNameSpecifier::TypeSpecWithTemplate);
+      break;
+
+    case NestedNameSpecifier::Global:
+      // Don't need to write an associated value.
+      break;
+    }
+  }
+}
+
+void PCHWriter::AddTemplateName(TemplateName Name, RecordData &Record) {
+  TemplateName::NameKind Kind = Name.getKind(); 
+  Record.push_back(Kind);
+  switch (Kind) {
+  case TemplateName::Template:
+    AddDeclRef(Name.getAsTemplateDecl(), Record);
+    break;
+
+  case TemplateName::OverloadedTemplate: {
+    OverloadedTemplateStorage *OvT = Name.getAsOverloadedTemplate();
+    Record.push_back(OvT->size());
+    for (OverloadedTemplateStorage::iterator I = OvT->begin(), E = OvT->end();
+           I != E; ++I)
+      AddDeclRef(*I, Record);
+    break;
+  }
+    
+  case TemplateName::QualifiedTemplate: {
+    QualifiedTemplateName *QualT = Name.getAsQualifiedTemplateName();
+    AddNestedNameSpecifier(QualT->getQualifier(), Record);
+    Record.push_back(QualT->hasTemplateKeyword());
+    AddDeclRef(QualT->getTemplateDecl(), Record);
+    break;
+  }
+    
+  case TemplateName::DependentTemplate: {
+    DependentTemplateName *DepT = Name.getAsDependentTemplateName();
+    AddNestedNameSpecifier(DepT->getQualifier(), Record);
+    Record.push_back(DepT->isIdentifier());
+    if (DepT->isIdentifier())
+      AddIdentifierRef(DepT->getIdentifier(), Record);
+    else
+      Record.push_back(DepT->getOperator());
+    break;
+  }
+  }
+}
+
+void PCHWriter::AddTemplateArgument(const TemplateArgument &Arg, 
+                                    RecordData &Record) {
+  Record.push_back(Arg.getKind());
+  switch (Arg.getKind()) {
+  case TemplateArgument::Null:
+    break;
+  case TemplateArgument::Type:
+    AddTypeRef(Arg.getAsType(), Record);
+    break;
+  case TemplateArgument::Declaration:
+    AddDeclRef(Arg.getAsDecl(), Record);
+    break;
+  case TemplateArgument::Integral:
+    AddAPSInt(*Arg.getAsIntegral(), Record);
+    AddTypeRef(Arg.getIntegralType(), Record);
+    break;
+  case TemplateArgument::Template:
+    AddTemplateName(Arg.getAsTemplate(), Record);
+    break;
+  case TemplateArgument::Expression:
+    AddStmt(Arg.getAsExpr());
+    break;
+  case TemplateArgument::Pack:
+    Record.push_back(Arg.pack_size());
+    for (TemplateArgument::pack_iterator I=Arg.pack_begin(), E=Arg.pack_end();
+           I != E; ++I)
+      AddTemplateArgument(*I, Record);
+    break;
+  }
+}
+
+void
+PCHWriter::AddTemplateParameterList(const TemplateParameterList *TemplateParams,
+                                    RecordData &Record) {
+  assert(TemplateParams && "No TemplateParams!");
+  AddSourceLocation(TemplateParams->getTemplateLoc(), Record);
+  AddSourceLocation(TemplateParams->getLAngleLoc(), Record);
+  AddSourceLocation(TemplateParams->getRAngleLoc(), Record);
+  Record.push_back(TemplateParams->size());
+  for (TemplateParameterList::const_iterator
+         P = TemplateParams->begin(), PEnd = TemplateParams->end();
+         P != PEnd; ++P)
+    AddDeclRef(*P, Record);
+}
+
+/// \brief Emit a template argument list.
+void
+PCHWriter::AddTemplateArgumentList(const TemplateArgumentList *TemplateArgs,
+                                   RecordData &Record) {
+  assert(TemplateArgs && "No TemplateArgs!");
+  Record.push_back(TemplateArgs->flat_size());
+  for (int i=0, e = TemplateArgs->flat_size(); i != e; ++i)
+    AddTemplateArgument(TemplateArgs->get(i), Record);
+}
+
+
+void
+PCHWriter::AddUnresolvedSet(const UnresolvedSetImpl &Set, RecordData &Record) {
+  Record.push_back(Set.size());
+  for (UnresolvedSetImpl::const_iterator
+         I = Set.begin(), E = Set.end(); I != E; ++I) {
+    AddDeclRef(I.getDecl(), Record);
+    Record.push_back(I.getAccess());
+  }
+}
+
+void PCHWriter::AddCXXBaseSpecifier(const CXXBaseSpecifier &Base,
+                                    RecordData &Record) {
+  Record.push_back(Base.isVirtual());
+  Record.push_back(Base.isBaseOfClass());
+  Record.push_back(Base.getAccessSpecifierAsWritten());
+  AddTypeSourceInfo(Base.getTypeSourceInfo(), Record);
+  AddSourceRange(Base.getSourceRange(), Record);
+}
+
+void PCHWriter::AddCXXBaseOrMemberInitializers(
+                        const CXXBaseOrMemberInitializer * const *BaseOrMembers,
+                        unsigned NumBaseOrMembers, RecordData &Record) {
+  Record.push_back(NumBaseOrMembers);
+  for (unsigned i=0; i != NumBaseOrMembers; ++i) {
+    const CXXBaseOrMemberInitializer *Init = BaseOrMembers[i];
+
+    Record.push_back(Init->isBaseInitializer());
+    if (Init->isBaseInitializer()) {
+      AddTypeSourceInfo(Init->getBaseClassInfo(), Record);
+      Record.push_back(Init->isBaseVirtual());
+    } else {
+      AddDeclRef(Init->getMember(), Record);
+    }
+    AddSourceLocation(Init->getMemberLocation(), Record);
+    AddStmt(Init->getInit());
+    AddDeclRef(Init->getAnonUnionMember(), Record);
+    AddSourceLocation(Init->getLParenLoc(), Record);
+    AddSourceLocation(Init->getRParenLoc(), Record);
+    Record.push_back(Init->isWritten());
+    if (Init->isWritten()) {
+      Record.push_back(Init->getSourceOrder());
+    } else {
+      Record.push_back(Init->getNumArrayIndices());
+      for (unsigned i=0, e=Init->getNumArrayIndices(); i != e; ++i)
+        AddDeclRef(Init->getArrayIndex(i), Record);
+    }
+  }
+}
+
+void PCHWriter::SetReader(PCHReader *Reader) {
+  assert(Reader && "Cannot remove chain");
+  assert(FirstDeclID == NextDeclID &&
+         FirstTypeID == NextTypeID &&
+         FirstIdentID == NextIdentID &&
+         FirstSelectorID == NextSelectorID &&
+         "Setting chain after writing has started.");
+  Chain = Reader;
+}
+
+void PCHWriter::IdentifierRead(pch::IdentID ID, IdentifierInfo *II) {
+  IdentifierIDs[II] = ID;
+}
+
+void PCHWriter::TypeRead(pch::TypeID ID, QualType T) {
+  TypeIDs[T] = ID;
+}
+
+void PCHWriter::DeclRead(pch::DeclID ID, const Decl *D) {
+  DeclIDs[D] = ID;
+}
+
+void PCHWriter::SelectorRead(pch::SelectorID ID, Selector S) {
+  SelectorIDs[S] = ID;
+}