lib/Serialization/ASTReader.cpp

//===--- ASTReader.cpp - AST File Reader ----------------------------------===//
//
//                     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 ASTReader class, which reads AST files.
//
//===----------------------------------------------------------------------===//

#include "clang/Serialization/ASTReader.h"
#include "ASTCommon.h"
#include "ASTReaderInternals.h"
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/NestedNameSpecifier.h"
#include "clang/AST/Type.h"
#include "clang/AST/TypeLocVisitor.h"
#include "clang/Basic/FileManager.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/SourceManagerInternals.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Basic/TargetOptions.h"
#include "clang/Basic/Version.h"
#include "clang/Basic/VersionTuple.h"
#include "clang/Lex/HeaderSearch.h"
#include "clang/Lex/HeaderSearchOptions.h"
#include "clang/Lex/MacroInfo.h"
#include "clang/Lex/PreprocessingRecord.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Lex/PreprocessorOptions.h"
#include "clang/Sema/Scope.h"
#include "clang/Sema/Sema.h"
#include "clang/Serialization/ASTDeserializationListener.h"
#include "clang/Serialization/GlobalModuleIndex.h"
#include "clang/Serialization/ModuleManager.h"
#include "clang/Serialization/SerializationDiagnostic.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Bitcode/BitstreamReader.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/system_error.h"
#include <algorithm>
#include <cstdio>
#include <iterator>

using namespace clang;
using namespace clang::serialization;
using namespace clang::serialization::reader;
using llvm::BitstreamCursor;


//===----------------------------------------------------------------------===//
// ChainedASTReaderListener implementation
//===----------------------------------------------------------------------===//

bool
ChainedASTReaderListener::ReadFullVersionInformation(StringRef FullVersion) {
  return First->ReadFullVersionInformation(FullVersion) ||
         Second->ReadFullVersionInformation(FullVersion);
}
void ChainedASTReaderListener::ReadModuleName(StringRef ModuleName) {
  First->ReadModuleName(ModuleName);
  Second->ReadModuleName(ModuleName);
}
void ChainedASTReaderListener::ReadModuleMapFile(StringRef ModuleMapPath) {
  First->ReadModuleMapFile(ModuleMapPath);
  Second->ReadModuleMapFile(ModuleMapPath);
}
bool ChainedASTReaderListener::ReadLanguageOptions(const LangOptions &LangOpts,
                                                   bool Complain) {
  return First->ReadLanguageOptions(LangOpts, Complain) ||
         Second->ReadLanguageOptions(LangOpts, Complain);
}
bool
ChainedASTReaderListener::ReadTargetOptions(const TargetOptions &TargetOpts,
                                            bool Complain) {
  return First->ReadTargetOptions(TargetOpts, Complain) ||
         Second->ReadTargetOptions(TargetOpts, Complain);
}
bool ChainedASTReaderListener::ReadDiagnosticOptions(
    const DiagnosticOptions &DiagOpts, bool Complain) {
  return First->ReadDiagnosticOptions(DiagOpts, Complain) ||
         Second->ReadDiagnosticOptions(DiagOpts, Complain);
}
bool
ChainedASTReaderListener::ReadFileSystemOptions(const FileSystemOptions &FSOpts,
                                                bool Complain) {
  return First->ReadFileSystemOptions(FSOpts, Complain) ||
         Second->ReadFileSystemOptions(FSOpts, Complain);
}

bool ChainedASTReaderListener::ReadHeaderSearchOptions(
    const HeaderSearchOptions &HSOpts, bool Complain) {
  return First->ReadHeaderSearchOptions(HSOpts, Complain) ||
         Second->ReadHeaderSearchOptions(HSOpts, Complain);
}
bool ChainedASTReaderListener::ReadPreprocessorOptions(
    const PreprocessorOptions &PPOpts, bool Complain,
    std::string &SuggestedPredefines) {
  return First->ReadPreprocessorOptions(PPOpts, Complain,
                                        SuggestedPredefines) ||
         Second->ReadPreprocessorOptions(PPOpts, Complain, SuggestedPredefines);
}
void ChainedASTReaderListener::ReadCounter(const serialization::ModuleFile &M,
                                           unsigned Value) {
  First->ReadCounter(M, Value);
  Second->ReadCounter(M, Value);
}
bool ChainedASTReaderListener::needsInputFileVisitation() {
  return First->needsInputFileVisitation() ||
         Second->needsInputFileVisitation();
}
bool ChainedASTReaderListener::needsSystemInputFileVisitation() {
  return First->needsSystemInputFileVisitation() ||
  Second->needsSystemInputFileVisitation();
}
void ChainedASTReaderListener::visitModuleFile(StringRef Filename) {
  First->visitModuleFile(Filename);
  Second->visitModuleFile(Filename);
}
bool ChainedASTReaderListener::visitInputFile(StringRef Filename,
                                              bool isSystem,
                                              bool isOverridden) {
  return First->visitInputFile(Filename, isSystem, isOverridden) ||
         Second->visitInputFile(Filename, isSystem, isOverridden);
}

//===----------------------------------------------------------------------===//
// PCH validator implementation
//===----------------------------------------------------------------------===//

ASTReaderListener::~ASTReaderListener() {}

/// \brief Compare the given set of language options against an existing set of
/// language options.
///
/// \param Diags If non-NULL, diagnostics will be emitted via this engine.
///
/// \returns true if the languagae options mis-match, false otherwise.
static bool checkLanguageOptions(const LangOptions &LangOpts,
                                 const LangOptions &ExistingLangOpts,
                                 DiagnosticsEngine *Diags) {
#define LANGOPT(Name, Bits, Default, Description)                 \
  if (ExistingLangOpts.Name != LangOpts.Name) {                   \
    if (Diags)                                                    \
      Diags->Report(diag::err_pch_langopt_mismatch)               \
        << Description << LangOpts.Name << ExistingLangOpts.Name; \
    return true;                                                  \
  }

#define VALUE_LANGOPT(Name, Bits, Default, Description)   \
  if (ExistingLangOpts.Name != LangOpts.Name) {           \
    if (Diags)                                            \
      Diags->Report(diag::err_pch_langopt_value_mismatch) \
        << Description;                                   \
    return true;                                          \
  }

#define ENUM_LANGOPT(Name, Type, Bits, Default, Description)   \
  if (ExistingLangOpts.get##Name() != LangOpts.get##Name()) {  \
    if (Diags)                                                 \
      Diags->Report(diag::err_pch_langopt_value_mismatch)      \
        << Description;                                        \
    return true;                                               \
  }

#define BENIGN_LANGOPT(Name, Bits, Default, Description)
#define BENIGN_ENUM_LANGOPT(Name, Type, Bits, Default, Description)
#include "clang/Basic/LangOptions.def"

  if (ExistingLangOpts.ObjCRuntime != LangOpts.ObjCRuntime) {
    if (Diags)
      Diags->Report(diag::err_pch_langopt_value_mismatch)
      << "target Objective-C runtime";
    return true;
  }

  if (ExistingLangOpts.CommentOpts.BlockCommandNames !=
      LangOpts.CommentOpts.BlockCommandNames) {
    if (Diags)
      Diags->Report(diag::err_pch_langopt_value_mismatch)
        << "block command names";
    return true;
  }

  return false;
}

/// \brief Compare the given set of target options against an existing set of
/// target options.
///
/// \param Diags If non-NULL, diagnostics will be emitted via this engine.
///
/// \returns true if the target options mis-match, false otherwise.
static bool checkTargetOptions(const TargetOptions &TargetOpts,
                               const TargetOptions &ExistingTargetOpts,
                               DiagnosticsEngine *Diags) {
#define CHECK_TARGET_OPT(Field, Name)                             \
  if (TargetOpts.Field != ExistingTargetOpts.Field) {             \
    if (Diags)                                                    \
      Diags->Report(diag::err_pch_targetopt_mismatch)             \
        << Name << TargetOpts.Field << ExistingTargetOpts.Field;  \
    return true;                                                  \
  }

  CHECK_TARGET_OPT(Triple, "target");
  CHECK_TARGET_OPT(CPU, "target CPU");
  CHECK_TARGET_OPT(ABI, "target ABI");
  CHECK_TARGET_OPT(LinkerVersion, "target linker version");
#undef CHECK_TARGET_OPT

  // Compare feature sets.
  SmallVector<StringRef, 4> ExistingFeatures(
                                             ExistingTargetOpts.FeaturesAsWritten.begin(),
                                             ExistingTargetOpts.FeaturesAsWritten.end());
  SmallVector<StringRef, 4> ReadFeatures(TargetOpts.FeaturesAsWritten.begin(),
                                         TargetOpts.FeaturesAsWritten.end());
  std::sort(ExistingFeatures.begin(), ExistingFeatures.end());
  std::sort(ReadFeatures.begin(), ReadFeatures.end());

  unsigned ExistingIdx = 0, ExistingN = ExistingFeatures.size();
  unsigned ReadIdx = 0, ReadN = ReadFeatures.size();
  while (ExistingIdx < ExistingN && ReadIdx < ReadN) {
    if (ExistingFeatures[ExistingIdx] == ReadFeatures[ReadIdx]) {
      ++ExistingIdx;
      ++ReadIdx;
      continue;
    }

    if (ReadFeatures[ReadIdx] < ExistingFeatures[ExistingIdx]) {
      if (Diags)
        Diags->Report(diag::err_pch_targetopt_feature_mismatch)
          << false << ReadFeatures[ReadIdx];
      return true;
    }

    if (Diags)
      Diags->Report(diag::err_pch_targetopt_feature_mismatch)
        << true << ExistingFeatures[ExistingIdx];
    return true;
  }

  if (ExistingIdx < ExistingN) {
    if (Diags)
      Diags->Report(diag::err_pch_targetopt_feature_mismatch)
        << true << ExistingFeatures[ExistingIdx];
    return true;
  }

  if (ReadIdx < ReadN) {
    if (Diags)
      Diags->Report(diag::err_pch_targetopt_feature_mismatch)
        << false << ReadFeatures[ReadIdx];
    return true;
  }

  return false;
}

bool
PCHValidator::ReadLanguageOptions(const LangOptions &LangOpts,
                                  bool Complain) {
  const LangOptions &ExistingLangOpts = PP.getLangOpts();
  return checkLanguageOptions(LangOpts, ExistingLangOpts,
                              Complain? &Reader.Diags : 0);
}

bool PCHValidator::ReadTargetOptions(const TargetOptions &TargetOpts,
                                     bool Complain) {
  const TargetOptions &ExistingTargetOpts = PP.getTargetInfo().getTargetOpts();
  return checkTargetOptions(TargetOpts, ExistingTargetOpts,
                            Complain? &Reader.Diags : 0);
}

namespace {
  typedef llvm::StringMap<std::pair<StringRef, bool /*IsUndef*/> >
    MacroDefinitionsMap;
  typedef llvm::DenseMap<DeclarationName, SmallVector<NamedDecl *, 8> >
    DeclsMap;
}

/// \brief Collect the macro definitions provided by the given preprocessor
/// options.
static void collectMacroDefinitions(const PreprocessorOptions &PPOpts,
                                    MacroDefinitionsMap &Macros,
                                    SmallVectorImpl<StringRef> *MacroNames = 0){
  for (unsigned I = 0, N = PPOpts.Macros.size(); I != N; ++I) {
    StringRef Macro = PPOpts.Macros[I].first;
    bool IsUndef = PPOpts.Macros[I].second;

    std::pair<StringRef, StringRef> MacroPair = Macro.split('=');
    StringRef MacroName = MacroPair.first;
    StringRef MacroBody = MacroPair.second;

    // For an #undef'd macro, we only care about the name.
    if (IsUndef) {
      if (MacroNames && !Macros.count(MacroName))
        MacroNames->push_back(MacroName);

      Macros[MacroName] = std::make_pair("", true);
      continue;
    }

    // For a #define'd macro, figure out the actual definition.
    if (MacroName.size() == Macro.size())
      MacroBody = "1";
    else {
      // Note: GCC drops anything following an end-of-line character.
      StringRef::size_type End = MacroBody.find_first_of("\n\r");
      MacroBody = MacroBody.substr(0, End);
    }

    if (MacroNames && !Macros.count(MacroName))
      MacroNames->push_back(MacroName);
    Macros[MacroName] = std::make_pair(MacroBody, false);
  }
}
         
/// \brief Check the preprocessor options deserialized from the control block
/// against the preprocessor options in an existing preprocessor.
///
/// \param Diags If non-null, produce diagnostics for any mismatches incurred.
static bool checkPreprocessorOptions(const PreprocessorOptions &PPOpts,
                                     const PreprocessorOptions &ExistingPPOpts,
                                     DiagnosticsEngine *Diags,
                                     FileManager &FileMgr,
                                     std::string &SuggestedPredefines,
                                     const LangOptions &LangOpts) {
  // Check macro definitions.
  MacroDefinitionsMap ASTFileMacros;
  collectMacroDefinitions(PPOpts, ASTFileMacros);
  MacroDefinitionsMap ExistingMacros;
  SmallVector<StringRef, 4> ExistingMacroNames;
  collectMacroDefinitions(ExistingPPOpts, ExistingMacros, &ExistingMacroNames);

  for (unsigned I = 0, N = ExistingMacroNames.size(); I != N; ++I) {
    // Dig out the macro definition in the existing preprocessor options.
    StringRef MacroName = ExistingMacroNames[I];
    std::pair<StringRef, bool> Existing = ExistingMacros[MacroName];

    // Check whether we know anything about this macro name or not.
    llvm::StringMap<std::pair<StringRef, bool /*IsUndef*/> >::iterator Known
      = ASTFileMacros.find(MacroName);
    if (Known == ASTFileMacros.end()) {
      // FIXME: Check whether this identifier was referenced anywhere in the
      // AST file. If so, we should reject the AST file. Unfortunately, this
      // information isn't in the control block. What shall we do about it?

      if (Existing.second) {
        SuggestedPredefines += "#undef ";
        SuggestedPredefines += MacroName.str();
        SuggestedPredefines += '\n';
      } else {
        SuggestedPredefines += "#define ";
        SuggestedPredefines += MacroName.str();
        SuggestedPredefines += ' ';
        SuggestedPredefines += Existing.first.str();
        SuggestedPredefines += '\n';
      }
      continue;
    }

    // If the macro was defined in one but undef'd in the other, we have a
    // conflict.
    if (Existing.second != Known->second.second) {
      if (Diags) {
        Diags->Report(diag::err_pch_macro_def_undef)
          << MacroName << Known->second.second;
      }
      return true;
    }

    // If the macro was #undef'd in both, or if the macro bodies are identical,
    // it's fine.
    if (Existing.second || Existing.first == Known->second.first)
      continue;

    // The macro bodies differ; complain.
    if (Diags) {
      Diags->Report(diag::err_pch_macro_def_conflict)
        << MacroName << Known->second.first << Existing.first;
    }
    return true;
  }

  // Check whether we're using predefines.
  if (PPOpts.UsePredefines != ExistingPPOpts.UsePredefines) {
    if (Diags) {
      Diags->Report(diag::err_pch_undef) << ExistingPPOpts.UsePredefines;
    }
    return true;
  }

  // Detailed record is important since it is used for the module cache hash.
  if (LangOpts.Modules &&
      PPOpts.DetailedRecord != ExistingPPOpts.DetailedRecord) {
    if (Diags) {
      Diags->Report(diag::err_pch_pp_detailed_record) << PPOpts.DetailedRecord;
    }
    return true;
  }

  // Compute the #include and #include_macros lines we need.
  for (unsigned I = 0, N = ExistingPPOpts.Includes.size(); I != N; ++I) {
    StringRef File = ExistingPPOpts.Includes[I];
    if (File == ExistingPPOpts.ImplicitPCHInclude)
      continue;

    if (std::find(PPOpts.Includes.begin(), PPOpts.Includes.end(), File)
          != PPOpts.Includes.end())
      continue;

    SuggestedPredefines += "#include \"";
    SuggestedPredefines +=
      HeaderSearch::NormalizeDashIncludePath(File, FileMgr);
    SuggestedPredefines += "\"\n";
  }

  for (unsigned I = 0, N = ExistingPPOpts.MacroIncludes.size(); I != N; ++I) {
    StringRef File = ExistingPPOpts.MacroIncludes[I];
    if (std::find(PPOpts.MacroIncludes.begin(), PPOpts.MacroIncludes.end(),
                  File)
        != PPOpts.MacroIncludes.end())
      continue;

    SuggestedPredefines += "#__include_macros \"";
    SuggestedPredefines +=
      HeaderSearch::NormalizeDashIncludePath(File, FileMgr);
    SuggestedPredefines += "\"\n##\n";
  }

  return false;
}

bool PCHValidator::ReadPreprocessorOptions(const PreprocessorOptions &PPOpts,
                                           bool Complain,
                                           std::string &SuggestedPredefines) {
  const PreprocessorOptions &ExistingPPOpts = PP.getPreprocessorOpts();

  return checkPreprocessorOptions(PPOpts, ExistingPPOpts,
                                  Complain? &Reader.Diags : 0,
                                  PP.getFileManager(),
                                  SuggestedPredefines,
                                  PP.getLangOpts());
}

void PCHValidator::ReadCounter(const ModuleFile &M, unsigned Value) {
  PP.setCounterValue(Value);
}

//===----------------------------------------------------------------------===//
// AST reader implementation
//===----------------------------------------------------------------------===//

void
ASTReader::setDeserializationListener(ASTDeserializationListener *Listener) {
  DeserializationListener = Listener;
}



unsigned ASTSelectorLookupTrait::ComputeHash(Selector Sel) {
  return serialization::ComputeHash(Sel);
}


std::pair<unsigned, unsigned>
ASTSelectorLookupTrait::ReadKeyDataLength(const unsigned char*& d) {
  using namespace llvm::support;
  unsigned KeyLen = endian::readNext<uint16_t, little, unaligned>(d);
  unsigned DataLen = endian::readNext<uint16_t, little, unaligned>(d);
  return std::make_pair(KeyLen, DataLen);
}

ASTSelectorLookupTrait::internal_key_type 
ASTSelectorLookupTrait::ReadKey(const unsigned char* d, unsigned) {
  using namespace llvm::support;
  SelectorTable &SelTable = Reader.getContext().Selectors;
  unsigned N = endian::readNext<uint16_t, little, unaligned>(d);
  IdentifierInfo *FirstII = Reader.getLocalIdentifier(
      F, endian::readNext<uint32_t, little, unaligned>(d));
  if (N == 0)
    return SelTable.getNullarySelector(FirstII);
  else if (N == 1)
    return SelTable.getUnarySelector(FirstII);

  SmallVector<IdentifierInfo *, 16> Args;
  Args.push_back(FirstII);
  for (unsigned I = 1; I != N; ++I)
    Args.push_back(Reader.getLocalIdentifier(
        F, endian::readNext<uint32_t, little, unaligned>(d)));

  return SelTable.getSelector(N, Args.data());
}

ASTSelectorLookupTrait::data_type 
ASTSelectorLookupTrait::ReadData(Selector, const unsigned char* d, 
                                 unsigned DataLen) {
  using namespace llvm::support;

  data_type Result;

  Result.ID = Reader.getGlobalSelectorID(
      F, endian::readNext<uint32_t, little, unaligned>(d));
  unsigned NumInstanceMethodsAndBits =
      endian::readNext<uint16_t, little, unaligned>(d);
  unsigned NumFactoryMethodsAndBits =
      endian::readNext<uint16_t, little, unaligned>(d);
  Result.InstanceBits = NumInstanceMethodsAndBits & 0x3;
  Result.FactoryBits = NumFactoryMethodsAndBits & 0x3;
  unsigned NumInstanceMethods = NumInstanceMethodsAndBits >> 2;
  unsigned NumFactoryMethods = NumFactoryMethodsAndBits >> 2;

  // Load instance methods
  for (unsigned I = 0; I != NumInstanceMethods; ++I) {
    if (ObjCMethodDecl *Method = Reader.GetLocalDeclAs<ObjCMethodDecl>(
            F, endian::readNext<uint32_t, little, unaligned>(d)))
      Result.Instance.push_back(Method);
  }

  // Load factory methods
  for (unsigned I = 0; I != NumFactoryMethods; ++I) {
    if (ObjCMethodDecl *Method = Reader.GetLocalDeclAs<ObjCMethodDecl>(
            F, endian::readNext<uint32_t, little, unaligned>(d)))
      Result.Factory.push_back(Method);
  }

  return Result;
}

unsigned ASTIdentifierLookupTraitBase::ComputeHash(const internal_key_type& a) {
  return llvm::HashString(a);
}

std::pair<unsigned, unsigned>
ASTIdentifierLookupTraitBase::ReadKeyDataLength(const unsigned char*& d) {
  using namespace llvm::support;
  unsigned DataLen = endian::readNext<uint16_t, little, unaligned>(d);
  unsigned KeyLen = endian::readNext<uint16_t, little, unaligned>(d);
  return std::make_pair(KeyLen, DataLen);
}

ASTIdentifierLookupTraitBase::internal_key_type
ASTIdentifierLookupTraitBase::ReadKey(const unsigned char* d, unsigned n) {
  assert(n >= 2 && d[n-1] == '\0');
  return StringRef((const char*) d, n-1);
}

/// \brief Whether the given identifier is "interesting".
static bool isInterestingIdentifier(IdentifierInfo &II) {
  return II.isPoisoned() ||
         II.isExtensionToken() ||
         II.getObjCOrBuiltinID() ||
         II.hasRevertedTokenIDToIdentifier() ||
         II.hadMacroDefinition() ||
         II.getFETokenInfo<void>();
}

IdentifierInfo *ASTIdentifierLookupTrait::ReadData(const internal_key_type& k,
                                                   const unsigned char* d,
                                                   unsigned DataLen) {
  using namespace llvm::support;
  unsigned RawID = endian::readNext<uint32_t, little, unaligned>(d);
  bool IsInteresting = RawID & 0x01;

  // Wipe out the "is interesting" bit.
  RawID = RawID >> 1;

  IdentID ID = Reader.getGlobalIdentifierID(F, RawID);
  if (!IsInteresting) {
    // For uninteresting identifiers, just build the IdentifierInfo
    // and associate it with the persistent ID.
    IdentifierInfo *II = KnownII;
    if (!II) {
      II = &Reader.getIdentifierTable().getOwn(k);
      KnownII = II;
    }
    Reader.SetIdentifierInfo(ID, II);
    if (!II->isFromAST()) {
      bool WasInteresting = isInterestingIdentifier(*II);
      II->setIsFromAST();
      if (WasInteresting)
        II->setChangedSinceDeserialization();
    }
    Reader.markIdentifierUpToDate(II);
    return II;
  }

  unsigned ObjCOrBuiltinID = endian::readNext<uint16_t, little, unaligned>(d);
  unsigned Bits = endian::readNext<uint16_t, little, unaligned>(d);
  bool CPlusPlusOperatorKeyword = Bits & 0x01;
  Bits >>= 1;
  bool HasRevertedTokenIDToIdentifier = Bits & 0x01;
  Bits >>= 1;
  bool Poisoned = Bits & 0x01;
  Bits >>= 1;
  bool ExtensionToken = Bits & 0x01;
  Bits >>= 1;
  bool hasSubmoduleMacros = Bits & 0x01;
  Bits >>= 1;
  bool hadMacroDefinition = Bits & 0x01;
  Bits >>= 1;

  assert(Bits == 0 && "Extra bits in the identifier?");
  DataLen -= 8;

  // Build the IdentifierInfo itself and link the identifier ID with
  // the new IdentifierInfo.
  IdentifierInfo *II = KnownII;
  if (!II) {
    II = &Reader.getIdentifierTable().getOwn(StringRef(k));
    KnownII = II;
  }
  Reader.markIdentifierUpToDate(II);
  if (!II->isFromAST()) {
    bool WasInteresting = isInterestingIdentifier(*II);
    II->setIsFromAST();
    if (WasInteresting)
      II->setChangedSinceDeserialization();
  }

  // Set or check the various bits in the IdentifierInfo structure.
  // Token IDs are read-only.
  if (HasRevertedTokenIDToIdentifier && II->getTokenID() != tok::identifier)
    II->RevertTokenIDToIdentifier();
  II->setObjCOrBuiltinID(ObjCOrBuiltinID);
  assert(II->isExtensionToken() == ExtensionToken &&
         "Incorrect extension token flag");
  (void)ExtensionToken;
  if (Poisoned)
    II->setIsPoisoned(true);
  assert(II->isCPlusPlusOperatorKeyword() == CPlusPlusOperatorKeyword &&
         "Incorrect C++ operator keyword flag");
  (void)CPlusPlusOperatorKeyword;

  // If this identifier is a macro, deserialize the macro
  // definition.
  if (hadMacroDefinition) {
    uint32_t MacroDirectivesOffset =
        endian::readNext<uint32_t, little, unaligned>(d);
    DataLen -= 4;
    SmallVector<uint32_t, 8> LocalMacroIDs;
    if (hasSubmoduleMacros) {
      while (uint32_t LocalMacroID =
                 endian::readNext<uint32_t, little, unaligned>(d)) {
        DataLen -= 4;
        LocalMacroIDs.push_back(LocalMacroID);
      }
      DataLen -= 4;
    }

    if (F.Kind == MK_Module) {
      // Macro definitions are stored from newest to oldest, so reverse them
      // before registering them.
      llvm::SmallVector<unsigned, 8> MacroSizes;
      for (SmallVectorImpl<uint32_t>::iterator
             I = LocalMacroIDs.begin(), E = LocalMacroIDs.end(); I != E; /**/) {
        unsigned Size = 1;

        static const uint32_t HasOverridesFlag = 0x80000000U;
        if (I + 1 != E && (I[1] & HasOverridesFlag))
          Size += 1 + (I[1] & ~HasOverridesFlag);

        MacroSizes.push_back(Size);
        I += Size;
      }

      SmallVectorImpl<uint32_t>::iterator I = LocalMacroIDs.end();
      for (SmallVectorImpl<unsigned>::reverse_iterator SI = MacroSizes.rbegin(),
                                                       SE = MacroSizes.rend();
           SI != SE; ++SI) {
        I -= *SI;

        uint32_t LocalMacroID = *I;
        llvm::ArrayRef<uint32_t> Overrides;
        if (*SI != 1)
          Overrides = llvm::makeArrayRef(&I[2], *SI - 2);
        Reader.addPendingMacroFromModule(II, &F, LocalMacroID, Overrides);
      }
      assert(I == LocalMacroIDs.begin());
    } else {
      Reader.addPendingMacroFromPCH(II, &F, MacroDirectivesOffset);
    }
  }

  Reader.SetIdentifierInfo(ID, II);

  // Read all of the declarations visible at global scope with this
  // name.
  if (DataLen > 0) {
    SmallVector<uint32_t, 4> DeclIDs;
    for (; DataLen > 0; DataLen -= 4)
      DeclIDs.push_back(Reader.getGlobalDeclID(
          F, endian::readNext<uint32_t, little, unaligned>(d)));
    Reader.SetGloballyVisibleDecls(II, DeclIDs);
  }

  return II;
}

unsigned 
ASTDeclContextNameLookupTrait::ComputeHash(const DeclNameKey &Key) const {
  llvm::FoldingSetNodeID ID;
  ID.AddInteger(Key.Kind);

  switch (Key.Kind) {
  case DeclarationName::Identifier:
  case DeclarationName::CXXLiteralOperatorName:
    ID.AddString(((IdentifierInfo*)Key.Data)->getName());
    break;
  case DeclarationName::ObjCZeroArgSelector:
  case DeclarationName::ObjCOneArgSelector:
  case DeclarationName::ObjCMultiArgSelector:
    ID.AddInteger(serialization::ComputeHash(Selector(Key.Data)));
    break;
  case DeclarationName::CXXOperatorName:
    ID.AddInteger((OverloadedOperatorKind)Key.Data);
    break;
  case DeclarationName::CXXConstructorName:
  case DeclarationName::CXXDestructorName:
  case DeclarationName::CXXConversionFunctionName:
  case DeclarationName::CXXUsingDirective:
    break;
  }

  return ID.ComputeHash();
}

ASTDeclContextNameLookupTrait::internal_key_type 
ASTDeclContextNameLookupTrait::GetInternalKey(
                                          const external_key_type& Name) const {
  DeclNameKey Key;
  Key.Kind = Name.getNameKind();
  switch (Name.getNameKind()) {
  case DeclarationName::Identifier:
    Key.Data = (uint64_t)Name.getAsIdentifierInfo();
    break;
  case DeclarationName::ObjCZeroArgSelector:
  case DeclarationName::ObjCOneArgSelector:
  case DeclarationName::ObjCMultiArgSelector:
    Key.Data = (uint64_t)Name.getObjCSelector().getAsOpaquePtr();
    break;
  case DeclarationName::CXXOperatorName:
    Key.Data = Name.getCXXOverloadedOperator();
    break;
  case DeclarationName::CXXLiteralOperatorName:
    Key.Data = (uint64_t)Name.getCXXLiteralIdentifier();
    break;
  case DeclarationName::CXXConstructorName:
  case DeclarationName::CXXDestructorName:
  case DeclarationName::CXXConversionFunctionName:
  case DeclarationName::CXXUsingDirective:
    Key.Data = 0;
    break;
  }

  return Key;
}

std::pair<unsigned, unsigned>
ASTDeclContextNameLookupTrait::ReadKeyDataLength(const unsigned char*& d) {
  using namespace llvm::support;
  unsigned KeyLen = endian::readNext<uint16_t, little, unaligned>(d);
  unsigned DataLen = endian::readNext<uint16_t, little, unaligned>(d);
  return std::make_pair(KeyLen, DataLen);
}

ASTDeclContextNameLookupTrait::internal_key_type 
ASTDeclContextNameLookupTrait::ReadKey(const unsigned char* d, unsigned) {
  using namespace llvm::support;

  DeclNameKey Key;
  Key.Kind = (DeclarationName::NameKind)*d++;
  switch (Key.Kind) {
  case DeclarationName::Identifier:
    Key.Data = (uint64_t)Reader.getLocalIdentifier(
        F, endian::readNext<uint32_t, little, unaligned>(d));
    break;
  case DeclarationName::ObjCZeroArgSelector:
  case DeclarationName::ObjCOneArgSelector:
  case DeclarationName::ObjCMultiArgSelector:
    Key.Data =
        (uint64_t)Reader.getLocalSelector(
                             F, endian::readNext<uint32_t, little, unaligned>(
                                    d)).getAsOpaquePtr();
    break;
  case DeclarationName::CXXOperatorName:
    Key.Data = *d++; // OverloadedOperatorKind
    break;
  case DeclarationName::CXXLiteralOperatorName:
    Key.Data = (uint64_t)Reader.getLocalIdentifier(
        F, endian::readNext<uint32_t, little, unaligned>(d));
    break;
  case DeclarationName::CXXConstructorName:
  case DeclarationName::CXXDestructorName:
  case DeclarationName::CXXConversionFunctionName:
  case DeclarationName::CXXUsingDirective:
    Key.Data = 0;
    break;
  }

  return Key;
}

ASTDeclContextNameLookupTrait::data_type 
ASTDeclContextNameLookupTrait::ReadData(internal_key_type, 
                                        const unsigned char* d,
                                        unsigned DataLen) {
  using namespace llvm::support;
  unsigned NumDecls = endian::readNext<uint16_t, little, unaligned>(d);
  LE32DeclID *Start = reinterpret_cast<LE32DeclID *>(
                        const_cast<unsigned char *>(d));
  return std::make_pair(Start, Start + NumDecls);
}

bool ASTReader::ReadDeclContextStorage(ModuleFile &M,
                                       BitstreamCursor &Cursor,
                                   const std::pair<uint64_t, uint64_t> &Offsets,
                                       DeclContextInfo &Info) {
  SavedStreamPosition SavedPosition(Cursor);
  // First the lexical decls.
  if (Offsets.first != 0) {
    Cursor.JumpToBit(Offsets.first);

    RecordData Record;
    StringRef Blob;
    unsigned Code = Cursor.ReadCode();
    unsigned RecCode = Cursor.readRecord(Code, Record, &Blob);
    if (RecCode != DECL_CONTEXT_LEXICAL) {
      Error("Expected lexical block");
      return true;
    }

    Info.LexicalDecls = reinterpret_cast<const KindDeclIDPair*>(Blob.data());
    Info.NumLexicalDecls = Blob.size() / sizeof(KindDeclIDPair);
  }

  // Now the lookup table.
  if (Offsets.second != 0) {
    Cursor.JumpToBit(Offsets.second);

    RecordData Record;
    StringRef Blob;
    unsigned Code = Cursor.ReadCode();
    unsigned RecCode = Cursor.readRecord(Code, Record, &Blob);
    if (RecCode != DECL_CONTEXT_VISIBLE) {
      Error("Expected visible lookup table block");
      return true;
    }
    Info.NameLookupTableData = ASTDeclContextNameLookupTable::Create(
        (const unsigned char *)Blob.data() + Record[0],
        (const unsigned char *)Blob.data() + sizeof(uint32_t),
        (const unsigned char *)Blob.data(),
        ASTDeclContextNameLookupTrait(*this, M));
  }

  return false;
}

void ASTReader::Error(StringRef Msg) {
  Error(diag::err_fe_pch_malformed, Msg);
  if (Context.getLangOpts().Modules && !Diags.isDiagnosticInFlight()) {
    Diag(diag::note_module_cache_path)
      << PP.getHeaderSearchInfo().getModuleCachePath();
  }
}

void ASTReader::Error(unsigned DiagID,
                      StringRef Arg1, StringRef Arg2) {
  if (Diags.isDiagnosticInFlight())
    Diags.SetDelayedDiagnostic(DiagID, Arg1, Arg2);
  else
    Diag(DiagID) << Arg1 << Arg2;
}

//===----------------------------------------------------------------------===//
// Source Manager Deserialization
//===----------------------------------------------------------------------===//

/// \brief Read the line table in the source manager block.
/// \returns true if there was an error.
bool ASTReader::ParseLineTable(ModuleFile &F,
                               SmallVectorImpl<uint64_t> &Record) {
  unsigned Idx = 0;
  LineTableInfo &LineTable = SourceMgr.getLineTable();

  // Parse the file names
  std::map<int, int> FileIDs;
  for (int I = 0, N = Record[Idx++]; I != N; ++I) {
    // Extract the file name
    unsigned FilenameLen = Record[Idx++];
    std::string Filename(&Record[Idx], &Record[Idx] + FilenameLen);
    Idx += FilenameLen;
    MaybeAddSystemRootToFilename(F, Filename);
    FileIDs[I] = LineTable.getLineTableFilenameID(Filename);
  }

  // Parse the line entries
  std::vector<LineEntry> Entries;
  while (Idx < Record.size()) {
    int FID = Record[Idx++];
    assert(FID >= 0 && "Serialized line entries for non-local file.");
    // Remap FileID from 1-based old view.
    FID += F.SLocEntryBaseID - 1;

    // Extract the line entries
    unsigned NumEntries = Record[Idx++];
    assert(NumEntries && "Numentries is 00000");
    Entries.clear();
    Entries.reserve(NumEntries);
    for (unsigned I = 0; I != NumEntries; ++I) {
      unsigned FileOffset = Record[Idx++];
      unsigned LineNo = Record[Idx++];
      int FilenameID = FileIDs[Record[Idx++]];
      SrcMgr::CharacteristicKind FileKind
        = (SrcMgr::CharacteristicKind)Record[Idx++];
      unsigned IncludeOffset = Record[Idx++];
      Entries.push_back(LineEntry::get(FileOffset, LineNo, FilenameID,
                                       FileKind, IncludeOffset));
    }
    LineTable.AddEntry(FileID::get(FID), Entries);
  }

  return false;
}

/// \brief Read a source manager block
bool ASTReader::ReadSourceManagerBlock(ModuleFile &F) {
  using namespace SrcMgr;

  BitstreamCursor &SLocEntryCursor = F.SLocEntryCursor;

  // Set the source-location entry cursor to the current position in
  // the stream. This cursor will be used to read the contents of the
  // source manager block initially, and then lazily read
  // source-location entries as needed.
  SLocEntryCursor = F.Stream;

  // The stream itself is going to skip over the source manager block.
  if (F.Stream.SkipBlock()) {
    Error("malformed block record in AST file");
    return true;
  }

  // Enter the source manager block.
  if (SLocEntryCursor.EnterSubBlock(SOURCE_MANAGER_BLOCK_ID)) {
    Error("malformed source manager block record in AST file");
    return true;
  }

  RecordData Record;
  while (true) {
    llvm::BitstreamEntry E = SLocEntryCursor.advanceSkippingSubblocks();
    
    switch (E.Kind) {
    case llvm::BitstreamEntry::SubBlock: // Handled for us already.
    case llvm::BitstreamEntry::Error:
      Error("malformed block record in AST file");
      return true;
    case llvm::BitstreamEntry::EndBlock:
      return false;
    case llvm::BitstreamEntry::Record:
      // The interesting case.
      break;
    }
    
    // Read a record.
    Record.clear();
    StringRef Blob;
    switch (SLocEntryCursor.readRecord(E.ID, Record, &Blob)) {
    default:  // Default behavior: ignore.
      break;

    case SM_SLOC_FILE_ENTRY:
    case SM_SLOC_BUFFER_ENTRY:
    case SM_SLOC_EXPANSION_ENTRY:
      // Once we hit one of the source location entries, we're done.
      return false;
    }
  }
}

/// \brief If a header file is not found at the path that we expect it to be
/// and the PCH file was moved from its original location, try to resolve the
/// file by assuming that header+PCH were moved together and the header is in
/// the same place relative to the PCH.
static std::string
resolveFileRelativeToOriginalDir(const std::string &Filename,
                                 const std::string &OriginalDir,
                                 const std::string &CurrDir) {
  assert(OriginalDir != CurrDir &&
         "No point trying to resolve the file if the PCH dir didn't change");
  using namespace llvm::sys;
  SmallString<128> filePath(Filename);
  fs::make_absolute(filePath);
  assert(path::is_absolute(OriginalDir));
  SmallString<128> currPCHPath(CurrDir);

  path::const_iterator fileDirI = path::begin(path::parent_path(filePath)),
                       fileDirE = path::end(path::parent_path(filePath));
  path::const_iterator origDirI = path::begin(OriginalDir),
                       origDirE = path::end(OriginalDir);
  // Skip the common path components from filePath and OriginalDir.
  while (fileDirI != fileDirE && origDirI != origDirE &&
         *fileDirI == *origDirI) {
    ++fileDirI;
    ++origDirI;
  }
  for (; origDirI != origDirE; ++origDirI)
    path::append(currPCHPath, "..");
  path::append(currPCHPath, fileDirI, fileDirE);
  path::append(currPCHPath, path::filename(Filename));
  return currPCHPath.str();
}

bool ASTReader::ReadSLocEntry(int ID) {
  if (ID == 0)
    return false;

  if (unsigned(-ID) - 2 >= getTotalNumSLocs() || ID > 0) {
    Error("source location entry ID out-of-range for AST file");
    return true;
  }

  ModuleFile *F = GlobalSLocEntryMap.find(-ID)->second;
  F->SLocEntryCursor.JumpToBit(F->SLocEntryOffsets[ID - F->SLocEntryBaseID]);
  BitstreamCursor &SLocEntryCursor = F->SLocEntryCursor;
  unsigned BaseOffset = F->SLocEntryBaseOffset;

  ++NumSLocEntriesRead;
  llvm::BitstreamEntry Entry = SLocEntryCursor.advance();
  if (Entry.Kind != llvm::BitstreamEntry::Record) {
    Error("incorrectly-formatted source location entry in AST file");
    return true;
  }
  
  RecordData Record;
  StringRef Blob;
  switch (SLocEntryCursor.readRecord(Entry.ID, Record, &Blob)) {
  default:
    Error("incorrectly-formatted source location entry in AST file");
    return true;

  case SM_SLOC_FILE_ENTRY: {
    // We will detect whether a file changed and return 'Failure' for it, but
    // we will also try to fail gracefully by setting up the SLocEntry.
    unsigned InputID = Record[4];
    InputFile IF = getInputFile(*F, InputID);
    const FileEntry *File = IF.getFile();
    bool OverriddenBuffer = IF.isOverridden();

    // Note that we only check if a File was returned. If it was out-of-date
    // we have complained but we will continue creating a FileID to recover
    // gracefully.
    if (!File)
      return true;

    SourceLocation IncludeLoc = ReadSourceLocation(*F, Record[1]);
    if (IncludeLoc.isInvalid() && F->Kind != MK_MainFile) {
      // This is the module's main file.
      IncludeLoc = getImportLocation(F);
    }
    SrcMgr::CharacteristicKind
      FileCharacter = (SrcMgr::CharacteristicKind)Record[2];
    FileID FID = SourceMgr.createFileID(File, IncludeLoc, FileCharacter,
                                        ID, BaseOffset + Record[0]);
    SrcMgr::FileInfo &FileInfo =
          const_cast<SrcMgr::FileInfo&>(SourceMgr.getSLocEntry(FID).getFile());
    FileInfo.NumCreatedFIDs = Record[5];
    if (Record[3])
      FileInfo.setHasLineDirectives();

    const DeclID *FirstDecl = F->FileSortedDecls + Record[6];
    unsigned NumFileDecls = Record[7];
    if (NumFileDecls) {
      assert(F->FileSortedDecls && "FILE_SORTED_DECLS not encountered yet ?");
      FileDeclIDs[FID] = FileDeclsInfo(F, llvm::makeArrayRef(FirstDecl,
                                                             NumFileDecls));
    }
    
    const SrcMgr::ContentCache *ContentCache
      = SourceMgr.getOrCreateContentCache(File,
                              /*isSystemFile=*/FileCharacter != SrcMgr::C_User);
    if (OverriddenBuffer && !ContentCache->BufferOverridden &&
        ContentCache->ContentsEntry == ContentCache->OrigEntry) {
      unsigned Code = SLocEntryCursor.ReadCode();
      Record.clear();
      unsigned RecCode = SLocEntryCursor.readRecord(Code, Record, &Blob);
      
      if (RecCode != SM_SLOC_BUFFER_BLOB) {
        Error("AST record has invalid code");
        return true;
      }
      
      llvm::MemoryBuffer *Buffer
        = llvm::MemoryBuffer::getMemBuffer(Blob.drop_back(1), File->getName());
      SourceMgr.overrideFileContents(File, Buffer);
    }

    break;
  }

  case SM_SLOC_BUFFER_ENTRY: {
    const char *Name = Blob.data();
    unsigned Offset = Record[0];
    SrcMgr::CharacteristicKind
      FileCharacter = (SrcMgr::CharacteristicKind)Record[2];
    SourceLocation IncludeLoc = ReadSourceLocation(*F, Record[1]);
    if (IncludeLoc.isInvalid() && F->Kind == MK_Module) {
      IncludeLoc = getImportLocation(F);
    }
    unsigned Code = SLocEntryCursor.ReadCode();
    Record.clear();
    unsigned RecCode
      = SLocEntryCursor.readRecord(Code, Record, &Blob);

    if (RecCode != SM_SLOC_BUFFER_BLOB) {
      Error("AST record has invalid code");
      return true;
    }

    llvm::MemoryBuffer *Buffer
      = llvm::MemoryBuffer::getMemBuffer(Blob.drop_back(1), Name);
    SourceMgr.createFileIDForMemBuffer(Buffer, FileCharacter, ID,
                                       BaseOffset + Offset, IncludeLoc);
    break;
  }

  case SM_SLOC_EXPANSION_ENTRY: {
    SourceLocation SpellingLoc = ReadSourceLocation(*F, Record[1]);
    SourceMgr.createExpansionLoc(SpellingLoc,
                                     ReadSourceLocation(*F, Record[2]),
                                     ReadSourceLocation(*F, Record[3]),
                                     Record[4],
                                     ID,
                                     BaseOffset + Record[0]);
    break;
  }
  }

  return false;
}

std::pair<SourceLocation, StringRef> ASTReader::getModuleImportLoc(int ID) {
  if (ID == 0)
    return std::make_pair(SourceLocation(), "");

  if (unsigned(-ID) - 2 >= getTotalNumSLocs() || ID > 0) {
    Error("source location entry ID out-of-range for AST file");
    return std::make_pair(SourceLocation(), "");
  }

  // Find which module file this entry lands in.
  ModuleFile *M = GlobalSLocEntryMap.find(-ID)->second;
  if (M->Kind != MK_Module)
    return std::make_pair(SourceLocation(), "");

  // FIXME: Can we map this down to a particular submodule? That would be
  // ideal.
  return std::make_pair(M->ImportLoc, StringRef(M->ModuleName));
}

/// \brief Find the location where the module F is imported.
SourceLocation ASTReader::getImportLocation(ModuleFile *F) {
  if (F->ImportLoc.isValid())
    return F->ImportLoc;
  
  // Otherwise we have a PCH. It's considered to be "imported" at the first
  // location of its includer.
  if (F->ImportedBy.empty() || !F->ImportedBy[0]) {
    // Main file is the importer.
    assert(!SourceMgr.getMainFileID().isInvalid() && "missing main file");
    return SourceMgr.getLocForStartOfFile(SourceMgr.getMainFileID());
  }
  return F->ImportedBy[0]->FirstLoc;
}

/// ReadBlockAbbrevs - Enter a subblock of the specified BlockID with the
/// specified cursor.  Read the abbreviations that are at the top of the block
/// and then leave the cursor pointing into the block.
bool ASTReader::ReadBlockAbbrevs(BitstreamCursor &Cursor, unsigned BlockID) {
  if (Cursor.EnterSubBlock(BlockID)) {
    Error("malformed block record in AST file");
    return Failure;
  }

  while (true) {
    uint64_t Offset = Cursor.GetCurrentBitNo();
    unsigned Code = Cursor.ReadCode();

    // We expect all abbrevs to be at the start of the block.
    if (Code != llvm::bitc::DEFINE_ABBREV) {
      Cursor.JumpToBit(Offset);
      return false;
    }
    Cursor.ReadAbbrevRecord();
  }
}

Token ASTReader::ReadToken(ModuleFile &F, const RecordDataImpl &Record,
                           unsigned &Idx) {
  Token Tok;
  Tok.startToken();
  Tok.setLocation(ReadSourceLocation(F, Record, Idx));
  Tok.setLength(Record[Idx++]);
  if (IdentifierInfo *II = getLocalIdentifier(F, Record[Idx++]))
    Tok.setIdentifierInfo(II);
  Tok.setKind((tok::TokenKind)Record[Idx++]);
  Tok.setFlag((Token::TokenFlags)Record[Idx++]);
  return Tok;
}

MacroInfo *ASTReader::ReadMacroRecord(ModuleFile &F, uint64_t Offset) {
  BitstreamCursor &Stream = F.MacroCursor;

  // Keep track of where we are in the stream, then jump back there
  // after reading this macro.
  SavedStreamPosition SavedPosition(Stream);

  Stream.JumpToBit(Offset);
  RecordData Record;
  SmallVector<IdentifierInfo*, 16> MacroArgs;
  MacroInfo *Macro = 0;

  while (true) {
    // Advance to the next record, but if we get to the end of the block, don't
    // pop it (removing all the abbreviations from the cursor) since we want to
    // be able to reseek within the block and read entries.
    unsigned Flags = BitstreamCursor::AF_DontPopBlockAtEnd;
    llvm::BitstreamEntry Entry = Stream.advanceSkippingSubblocks(Flags);
    
    switch (Entry.Kind) {
    case llvm::BitstreamEntry::SubBlock: // Handled for us already.
    case llvm::BitstreamEntry::Error:
      Error("malformed block record in AST file");
      return Macro;
    case llvm::BitstreamEntry::EndBlock:
      return Macro;
    case llvm::BitstreamEntry::Record:
      // The interesting case.
      break;
    }

    // Read a record.
    Record.clear();
    PreprocessorRecordTypes RecType =
      (PreprocessorRecordTypes)Stream.readRecord(Entry.ID, Record);
    switch (RecType) {
    case PP_MACRO_DIRECTIVE_HISTORY:
      return Macro;

    case PP_MACRO_OBJECT_LIKE:
    case PP_MACRO_FUNCTION_LIKE: {
      // If we already have a macro, that means that we've hit the end
      // of the definition of the macro we were looking for. We're
      // done.
      if (Macro)
        return Macro;

      unsigned NextIndex = 1; // Skip identifier ID.
      SubmoduleID SubModID = getGlobalSubmoduleID(F, Record[NextIndex++]);
      SourceLocation Loc = ReadSourceLocation(F, Record, NextIndex);
      MacroInfo *MI = PP.AllocateDeserializedMacroInfo(Loc, SubModID);
      MI->setDefinitionEndLoc(ReadSourceLocation(F, Record, NextIndex));
      MI->setIsUsed(Record[NextIndex++]);
      MI->setUsedForHeaderGuard(Record[NextIndex++]);

      if (RecType == PP_MACRO_FUNCTION_LIKE) {
        // Decode function-like macro info.
        bool isC99VarArgs = Record[NextIndex++];
        bool isGNUVarArgs = Record[NextIndex++];
        bool hasCommaPasting = Record[NextIndex++];
        MacroArgs.clear();
        unsigned NumArgs = Record[NextIndex++];
        for (unsigned i = 0; i != NumArgs; ++i)
          MacroArgs.push_back(getLocalIdentifier(F, Record[NextIndex++]));

        // Install function-like macro info.
        MI->setIsFunctionLike();
        if (isC99VarArgs) MI->setIsC99Varargs();
        if (isGNUVarArgs) MI->setIsGNUVarargs();
        if (hasCommaPasting) MI->setHasCommaPasting();
        MI->setArgumentList(MacroArgs.data(), MacroArgs.size(),
                            PP.getPreprocessorAllocator());
      }

      // Remember that we saw this macro last so that we add the tokens that
      // form its body to it.
      Macro = MI;

      if (NextIndex + 1 == Record.size() && PP.getPreprocessingRecord() &&
          Record[NextIndex]) {
        // We have a macro definition. Register the association
        PreprocessedEntityID
            GlobalID = getGlobalPreprocessedEntityID(F, Record[NextIndex]);
        PreprocessingRecord &PPRec = *PP.getPreprocessingRecord();
        PreprocessingRecord::PPEntityID
          PPID = PPRec.getPPEntityID(GlobalID-1, /*isLoaded=*/true);
        MacroDefinition *PPDef =
          cast_or_null<MacroDefinition>(PPRec.getPreprocessedEntity(PPID));
        if (PPDef)
          PPRec.RegisterMacroDefinition(Macro, PPDef);
      }

      ++NumMacrosRead;
      break;
    }

    case PP_TOKEN: {
      // If we see a TOKEN before a PP_MACRO_*, then the file is
      // erroneous, just pretend we didn't see this.
      if (Macro == 0) break;

      unsigned Idx = 0;
      Token Tok = ReadToken(F, Record, Idx);
      Macro->AddTokenToBody(Tok);
      break;
    }
    }
  }
}

PreprocessedEntityID 
ASTReader::getGlobalPreprocessedEntityID(ModuleFile &M, unsigned LocalID) const {
  ContinuousRangeMap<uint32_t, int, 2>::const_iterator 
    I = M.PreprocessedEntityRemap.find(LocalID - NUM_PREDEF_PP_ENTITY_IDS);
  assert(I != M.PreprocessedEntityRemap.end() 
         && "Invalid index into preprocessed entity index remap");
  
  return LocalID + I->second;
}

unsigned HeaderFileInfoTrait::ComputeHash(internal_key_ref ikey) {
  return llvm::hash_combine(ikey.Size, ikey.ModTime);
}
    
HeaderFileInfoTrait::internal_key_type 
HeaderFileInfoTrait::GetInternalKey(const FileEntry *FE) {
  internal_key_type ikey = { FE->getSize(), FE->getModificationTime(),
                             FE->getName() };
  return ikey;
}
    
bool HeaderFileInfoTrait::EqualKey(internal_key_ref a, internal_key_ref b) {
  if (a.Size != b.Size || a.ModTime != b.ModTime)
    return false;

  if (strcmp(a.Filename, b.Filename) == 0)
    return true;
  
  // Determine whether the actual files are equivalent.
  FileManager &FileMgr = Reader.getFileManager();
  const FileEntry *FEA = FileMgr.getFile(a.Filename);
  const FileEntry *FEB = FileMgr.getFile(b.Filename);
  return (FEA && FEA == FEB);
}
    
std::pair<unsigned, unsigned>
HeaderFileInfoTrait::ReadKeyDataLength(const unsigned char*& d) {
  using namespace llvm::support;
  unsigned KeyLen = (unsigned) endian::readNext<uint16_t, little, unaligned>(d);
  unsigned DataLen = (unsigned) *d++;
  return std::make_pair(KeyLen, DataLen);
}

HeaderFileInfoTrait::internal_key_type
HeaderFileInfoTrait::ReadKey(const unsigned char *d, unsigned) {
  using namespace llvm::support;
  internal_key_type ikey;
  ikey.Size = off_t(endian::readNext<uint64_t, little, unaligned>(d));
  ikey.ModTime = time_t(endian::readNext<uint64_t, little, unaligned>(d));
  ikey.Filename = (const char *)d;
  return ikey;
}

HeaderFileInfoTrait::data_type 
HeaderFileInfoTrait::ReadData(internal_key_ref key, const unsigned char *d,
                              unsigned DataLen) {
  const unsigned char *End = d + DataLen;
  using namespace llvm::support;
  HeaderFileInfo HFI;
  unsigned Flags = *d++;
  HFI.HeaderRole = static_cast<ModuleMap::ModuleHeaderRole>
                   ((Flags >> 6) & 0x03);
  HFI.isImport = (Flags >> 5) & 0x01;
  HFI.isPragmaOnce = (Flags >> 4) & 0x01;
  HFI.DirInfo = (Flags >> 2) & 0x03;
  HFI.Resolved = (Flags >> 1) & 0x01;
  HFI.IndexHeaderMapHeader = Flags & 0x01;
  HFI.NumIncludes = endian::readNext<uint16_t, little, unaligned>(d);
  HFI.ControllingMacroID = Reader.getGlobalIdentifierID(
      M, endian::readNext<uint32_t, little, unaligned>(d));
  if (unsigned FrameworkOffset =
          endian::readNext<uint32_t, little, unaligned>(d)) {
    // The framework offset is 1 greater than the actual offset, 
    // since 0 is used as an indicator for "no framework name".
    StringRef FrameworkName(FrameworkStrings + FrameworkOffset - 1);
    HFI.Framework = HS->getUniqueFrameworkName(FrameworkName);
  }
  
  if (d != End) {
    uint32_t LocalSMID = endian::readNext<uint32_t, little, unaligned>(d);
    if (LocalSMID) {
      // This header is part of a module. Associate it with the module to enable
      // implicit module import.
      SubmoduleID GlobalSMID = Reader.getGlobalSubmoduleID(M, LocalSMID);
      Module *Mod = Reader.getSubmodule(GlobalSMID);
      HFI.isModuleHeader = true;
      FileManager &FileMgr = Reader.getFileManager();
      ModuleMap &ModMap =
          Reader.getPreprocessor().getHeaderSearchInfo().getModuleMap();
      ModMap.addHeader(Mod, FileMgr.getFile(key.Filename), HFI.getHeaderRole());
    }
  }

  assert(End == d && "Wrong data length in HeaderFileInfo deserialization");
  (void)End;
        
  // This HeaderFileInfo was externally loaded.
  HFI.External = true;
  return HFI;
}

void
ASTReader::addPendingMacroFromModule(IdentifierInfo *II, ModuleFile *M,
                                     GlobalMacroID GMacID,
                                     llvm::ArrayRef<SubmoduleID> Overrides) {
  assert(NumCurrentElementsDeserializing > 0 &&"Missing deserialization guard");
  SubmoduleID *OverrideData = 0;
  if (!Overrides.empty()) {
    OverrideData = new (Context) SubmoduleID[Overrides.size() + 1];
    OverrideData[0] = Overrides.size();
    for (unsigned I = 0; I != Overrides.size(); ++I)
      OverrideData[I + 1] = getGlobalSubmoduleID(*M, Overrides[I]);
  }
  PendingMacroIDs[II].push_back(PendingMacroInfo(M, GMacID, OverrideData));
}

void ASTReader::addPendingMacroFromPCH(IdentifierInfo *II,
                                       ModuleFile *M,
                                       uint64_t MacroDirectivesOffset) {
  assert(NumCurrentElementsDeserializing > 0 &&"Missing deserialization guard");
  PendingMacroIDs[II].push_back(PendingMacroInfo(M, MacroDirectivesOffset));
}

void ASTReader::ReadDefinedMacros() {
  // Note that we are loading defined macros.
  Deserializing Macros(this);

  for (ModuleReverseIterator I = ModuleMgr.rbegin(),
      E = ModuleMgr.rend(); I != E; ++I) {
    BitstreamCursor &MacroCursor = (*I)->MacroCursor;

    // If there was no preprocessor block, skip this file.
    if (!MacroCursor.getBitStreamReader())
      continue;

    BitstreamCursor Cursor = MacroCursor;
    Cursor.JumpToBit((*I)->MacroStartOffset);

    RecordData Record;
    while (true) {
      llvm::BitstreamEntry E = Cursor.advanceSkippingSubblocks();
      
      switch (E.Kind) {
      case llvm::BitstreamEntry::SubBlock: // Handled for us already.
      case llvm::BitstreamEntry::Error:
        Error("malformed block record in AST file");
        return;
      case llvm::BitstreamEntry::EndBlock:
        goto NextCursor;
        
      case llvm::BitstreamEntry::Record:
        Record.clear();
        switch (Cursor.readRecord(E.ID, Record)) {
        default:  // Default behavior: ignore.
          break;
          
        case PP_MACRO_OBJECT_LIKE:
        case PP_MACRO_FUNCTION_LIKE:
          getLocalIdentifier(**I, Record[0]);
          break;
          
        case PP_TOKEN:
          // Ignore tokens.
          break;
        }
        break;
      }
    }
    NextCursor:  ;
  }
}

namespace {
  /// \brief Visitor class used to look up identifirs in an AST file.
  class IdentifierLookupVisitor {
    StringRef Name;
    unsigned PriorGeneration;
    unsigned &NumIdentifierLookups;
    unsigned &NumIdentifierLookupHits;
    IdentifierInfo *Found;

  public:
    IdentifierLookupVisitor(StringRef Name, unsigned PriorGeneration,
                            unsigned &NumIdentifierLookups,
                            unsigned &NumIdentifierLookupHits)
      : Name(Name), PriorGeneration(PriorGeneration),
        NumIdentifierLookups(NumIdentifierLookups),
        NumIdentifierLookupHits(NumIdentifierLookupHits),
        Found()
    {
    }
    
    static bool visit(ModuleFile &M, void *UserData) {
      IdentifierLookupVisitor *This
        = static_cast<IdentifierLookupVisitor *>(UserData);
      
      // If we've already searched this module file, skip it now.
      if (M.Generation <= This->PriorGeneration)
        return true;

      ASTIdentifierLookupTable *IdTable
        = (ASTIdentifierLookupTable *)M.IdentifierLookupTable;
      if (!IdTable)
        return false;
      
      ASTIdentifierLookupTrait Trait(IdTable->getInfoObj().getReader(),
                                     M, This->Found);
      ++This->NumIdentifierLookups;
      ASTIdentifierLookupTable::iterator Pos = IdTable->find(This->Name,&Trait);
      if (Pos == IdTable->end())
        return false;
      
      // Dereferencing the iterator has the effect of building the
      // IdentifierInfo node and populating it with the various
      // declarations it needs.
      ++This->NumIdentifierLookupHits;
      This->Found = *Pos;
      return true;
    }
    
    // \brief Retrieve the identifier info found within the module
    // files.
    IdentifierInfo *getIdentifierInfo() const { return Found; }
  };
}

void ASTReader::updateOutOfDateIdentifier(IdentifierInfo &II) {
  // Note that we are loading an identifier.
  Deserializing AnIdentifier(this);

  unsigned PriorGeneration = 0;
  if (getContext().getLangOpts().Modules)
    PriorGeneration = IdentifierGeneration[&II];

  // If there is a global index, look there first to determine which modules
  // provably do not have any results for this identifier.
  GlobalModuleIndex::HitSet Hits;
  GlobalModuleIndex::HitSet *HitsPtr = 0;
  if (!loadGlobalIndex()) {
    if (GlobalIndex->lookupIdentifier(II.getName(), Hits)) {
      HitsPtr = &Hits;
    }
  }

  IdentifierLookupVisitor Visitor(II.getName(), PriorGeneration,
                                  NumIdentifierLookups,
                                  NumIdentifierLookupHits);
  ModuleMgr.visit(IdentifierLookupVisitor::visit, &Visitor, HitsPtr);
  markIdentifierUpToDate(&II);
}

void ASTReader::markIdentifierUpToDate(IdentifierInfo *II) {
  if (!II)
    return;
  
  II->setOutOfDate(false);

  // Update the generation for this identifier.
  if (getContext().getLangOpts().Modules)
    IdentifierGeneration[II] = CurrentGeneration;
}

struct ASTReader::ModuleMacroInfo {
  SubmoduleID SubModID;
  MacroInfo *MI;
  SubmoduleID *Overrides;
  // FIXME: Remove this.
  ModuleFile *F;

  bool isDefine() const { return MI; }

  SubmoduleID getSubmoduleID() const { return SubModID; }

  llvm::ArrayRef<SubmoduleID> getOverriddenSubmodules() const {
    if (!Overrides)
      return llvm::ArrayRef<SubmoduleID>();
    return llvm::makeArrayRef(Overrides + 1, *Overrides);
  }

  DefMacroDirective *import(Preprocessor &PP, SourceLocation ImportLoc) const {
    if (!MI)
      return 0;
    return PP.AllocateDefMacroDirective(MI, ImportLoc, /*isImported=*/true);
  }
};

ASTReader::ModuleMacroInfo *
ASTReader::getModuleMacro(const PendingMacroInfo &PMInfo) {
  ModuleMacroInfo Info;

  uint32_t ID = PMInfo.ModuleMacroData.MacID;
  if (ID & 1) {
    // Macro undefinition.
    Info.SubModID = getGlobalSubmoduleID(*PMInfo.M, ID >> 1);
    Info.MI = 0;
  } else {
    // Macro definition.
    GlobalMacroID GMacID = getGlobalMacroID(*PMInfo.M, ID >> 1);
    assert(GMacID);

    // If this macro has already been loaded, don't do so again.
    // FIXME: This is highly dubious. Multiple macro definitions can have the
    // same MacroInfo (and hence the same GMacID) due to #pragma push_macro etc.
    if (MacrosLoaded[GMacID - NUM_PREDEF_MACRO_IDS])
      return 0;

    Info.MI = getMacro(GMacID);
    Info.SubModID = Info.MI->getOwningModuleID();
  }
  Info.Overrides = PMInfo.ModuleMacroData.Overrides;
  Info.F = PMInfo.M;

  return new (Context) ModuleMacroInfo(Info);
}

void ASTReader::resolvePendingMacro(IdentifierInfo *II,
                                    const PendingMacroInfo &PMInfo) {
  assert(II);

  if (PMInfo.M->Kind != MK_Module) {
    installPCHMacroDirectives(II, *PMInfo.M,
                              PMInfo.PCHMacroData.MacroDirectivesOffset);
    return;
  }

  // Module Macro.

  ModuleMacroInfo *MMI = getModuleMacro(PMInfo);
  if (!MMI)
    return;

  Module *Owner = getSubmodule(MMI->getSubmoduleID());
  if (Owner && Owner->NameVisibility == Module::Hidden) {
    // Macros in the owning module are hidden. Just remember this macro to
    // install if we make this module visible.
    HiddenNamesMap[Owner].HiddenMacros.insert(std::make_pair(II, MMI));
  } else {
    installImportedMacro(II, MMI, Owner);
  }
}

void ASTReader::installPCHMacroDirectives(IdentifierInfo *II,
                                          ModuleFile &M, uint64_t Offset) {
  assert(M.Kind != MK_Module);

  BitstreamCursor &Cursor = M.MacroCursor;
  SavedStreamPosition SavedPosition(Cursor);
  Cursor.JumpToBit(Offset);

  llvm::BitstreamEntry Entry =
      Cursor.advance(BitstreamCursor::AF_DontPopBlockAtEnd);
  if (Entry.Kind != llvm::BitstreamEntry::Record) {
    Error("malformed block record in AST file");
    return;
  }

  RecordData Record;
  PreprocessorRecordTypes RecType =
    (PreprocessorRecordTypes)Cursor.readRecord(Entry.ID, Record);
  if (RecType != PP_MACRO_DIRECTIVE_HISTORY) {
    Error("malformed block record in AST file");
    return;
  }

  // Deserialize the macro directives history in reverse source-order.
  MacroDirective *Latest = 0, *Earliest = 0;
  unsigned Idx = 0, N = Record.size();
  while (Idx < N) {
    MacroDirective *MD = 0;
    SourceLocation Loc = ReadSourceLocation(M, Record, Idx);
    MacroDirective::Kind K = (MacroDirective::Kind)Record[Idx++];
    switch (K) {
    case MacroDirective::MD_Define: {
      GlobalMacroID GMacID = getGlobalMacroID(M, Record[Idx++]);
      MacroInfo *MI = getMacro(GMacID);
      bool isImported = Record[Idx++];
      bool isAmbiguous = Record[Idx++];
      DefMacroDirective *DefMD =
          PP.AllocateDefMacroDirective(MI, Loc, isImported);
      DefMD->setAmbiguous(isAmbiguous);
      MD = DefMD;
      break;
    }
    case MacroDirective::MD_Undefine:
      MD = PP.AllocateUndefMacroDirective(Loc);
      break;
    case MacroDirective::MD_Visibility: {
      bool isPublic = Record[Idx++];
      MD = PP.AllocateVisibilityMacroDirective(Loc, isPublic);
      break;
    }
    }

    if (!Latest)
      Latest = MD;
    if (Earliest)
      Earliest->setPrevious(MD);
    Earliest = MD;
  }

  PP.setLoadedMacroDirective(II, Latest);
}

/// \brief For the given macro definitions, check if they are both in system
/// modules.
static bool areDefinedInSystemModules(MacroInfo *PrevMI, MacroInfo *NewMI,
                                      Module *NewOwner, ASTReader &Reader) {
  assert(PrevMI && NewMI);
  Module *PrevOwner = 0;
  if (SubmoduleID PrevModID = PrevMI->getOwningModuleID())
    PrevOwner = Reader.getSubmodule(PrevModID);
  SourceManager &SrcMgr = Reader.getSourceManager();
  bool PrevInSystem
    = PrevOwner? PrevOwner->IsSystem
               : SrcMgr.isInSystemHeader(PrevMI->getDefinitionLoc());
  bool NewInSystem
    = NewOwner? NewOwner->IsSystem
              : SrcMgr.isInSystemHeader(NewMI->getDefinitionLoc());
  if (PrevOwner && PrevOwner == NewOwner)
    return false;
  return PrevInSystem && NewInSystem;
}

void ASTReader::removeOverriddenMacros(IdentifierInfo *II,
                                       AmbiguousMacros &Ambig,
                                       llvm::ArrayRef<SubmoduleID> Overrides) {
  for (unsigned OI = 0, ON = Overrides.size(); OI != ON; ++OI) {
    SubmoduleID OwnerID = Overrides[OI];

    // If this macro is not yet visible, remove it from the hidden names list.
    Module *Owner = getSubmodule(OwnerID);
    HiddenNames &Hidden = HiddenNamesMap[Owner];
    HiddenMacrosMap::iterator HI = Hidden.HiddenMacros.find(II);
    if (HI != Hidden.HiddenMacros.end()) {
      auto SubOverrides = HI->second->getOverriddenSubmodules();
      Hidden.HiddenMacros.erase(HI);
      removeOverriddenMacros(II, Ambig, SubOverrides);
    }

    // If this macro is already in our list of conflicts, remove it from there.
    Ambig.erase(
        std::remove_if(Ambig.begin(), Ambig.end(), [&](DefMacroDirective *MD) {
          return MD->getInfo()->getOwningModuleID() == OwnerID;
        }),
        Ambig.end());
  }
}

ASTReader::AmbiguousMacros *
ASTReader::removeOverriddenMacros(IdentifierInfo *II,
                                  llvm::ArrayRef<SubmoduleID> Overrides) {
  MacroDirective *Prev = PP.getMacroDirective(II);
  if (!Prev && Overrides.empty())
    return 0;

  DefMacroDirective *PrevDef = Prev ? Prev->getDefinition().getDirective() : 0;
  if (PrevDef && PrevDef->isAmbiguous()) {
    // We had a prior ambiguity. Check whether we resolve it (or make it worse).
    AmbiguousMacros &Ambig = AmbiguousMacroDefs[II];
    Ambig.push_back(PrevDef);

    removeOverriddenMacros(II, Ambig, Overrides);

    if (!Ambig.empty())
      return &Ambig;

    AmbiguousMacroDefs.erase(II);
  } else {
    // There's no ambiguity yet. Maybe we're introducing one.
    llvm::SmallVector<DefMacroDirective*, 1> Ambig;
    if (PrevDef)
      Ambig.push_back(PrevDef);

    removeOverriddenMacros(II, Ambig, Overrides);

    if (!Ambig.empty()) {
      AmbiguousMacros &Result = AmbiguousMacroDefs[II];
      Result.swap(Ambig);
      return &Result;
    }
  }

  // We ended up with no ambiguity.
  return 0;
}

void ASTReader::installImportedMacro(IdentifierInfo *II, ModuleMacroInfo *MMI,
                                     Module *Owner) {
  assert(II && Owner);

  SourceLocation ImportLoc = Owner->MacroVisibilityLoc;
  if (ImportLoc.isInvalid()) {
    // FIXME: If we made macros from this module visible but didn't provide a
    // source location for the import, we don't have a location for the macro.
    // Use the location at which the containing module file was first imported
    // for now.
    ImportLoc = MMI->F->DirectImportLoc;
    assert(ImportLoc.isValid() && "no import location for a visible macro?");
  }

  llvm::SmallVectorImpl<DefMacroDirective*> *Prev =
      removeOverriddenMacros(II, MMI->getOverriddenSubmodules());


  // Create a synthetic macro definition corresponding to the import (or null
  // if this was an undefinition of the macro).
  DefMacroDirective *MD = MMI->import(PP, ImportLoc);

  // If there's no ambiguity, just install the macro.
  if (!Prev) {
    if (MD)
      PP.appendMacroDirective(II, MD);
    else
      PP.appendMacroDirective(II, PP.AllocateUndefMacroDirective(ImportLoc));
    return;
  }
  assert(!Prev->empty());

  if (!MD) {
    // We imported a #undef that didn't remove all prior definitions. The most
    // recent prior definition remains, and we install it in the place of the
    // imported directive.
    MacroInfo *NewMI = Prev->back()->getInfo();
    Prev->pop_back();
    MD = PP.AllocateDefMacroDirective(NewMI, ImportLoc, /*Imported*/true);
  }

  // We're introducing a macro definition that creates or adds to an ambiguity.
  // We can resolve that ambiguity if this macro is token-for-token identical to
  // all of the existing definitions.
  MacroInfo *NewMI = MD->getInfo();
  assert(NewMI && "macro definition with no MacroInfo?");
  while (!Prev->empty()) {
    MacroInfo *PrevMI = Prev->back()->getInfo();
    assert(PrevMI && "macro definition with no MacroInfo?");

    // Before marking the macros as ambiguous, check if this is a case where
    // both macros are in system headers. If so, we trust that the system
    // did not get it wrong. This also handles cases where Clang's own
    // headers have a different spelling of certain system macros:
    //   #define LONG_MAX __LONG_MAX__ (clang's limits.h)
    //   #define LONG_MAX 0x7fffffffffffffffL (system's limits.h)
    //
    // FIXME: Remove the defined-in-system-headers check. clang's limits.h
    // overrides the system limits.h's macros, so there's no conflict here.
    if (NewMI != PrevMI &&
        !PrevMI->isIdenticalTo(*NewMI, PP, /*Syntactically=*/true) &&
        !areDefinedInSystemModules(PrevMI, NewMI, Owner, *this))
      break;

    // The previous definition is the same as this one (or both are defined in
    // system modules so we can assume they're equivalent); we don't need to
    // track it any more.
    Prev->pop_back();
  }

  if (!Prev->empty())
    MD->setAmbiguous(true);

  PP.appendMacroDirective(II, MD);
}

ASTReader::InputFileInfo
ASTReader::readInputFileInfo(ModuleFile &F, unsigned ID) {
  // Go find this input file.
  BitstreamCursor &Cursor = F.InputFilesCursor;
  SavedStreamPosition SavedPosition(Cursor);
  Cursor.JumpToBit(F.InputFileOffsets[ID-1]);

  unsigned Code = Cursor.ReadCode();
  RecordData Record;
  StringRef Blob;

  unsigned Result = Cursor.readRecord(Code, Record, &Blob);
  assert(static_cast<InputFileRecordTypes>(Result) == INPUT_FILE &&
         "invalid record type for input file");
  (void)Result;

  std::string Filename;
  off_t StoredSize;
  time_t StoredTime;
  bool Overridden;
  
  assert(Record[0] == ID && "Bogus stored ID or offset");
  StoredSize = static_cast<off_t>(Record[1]);
  StoredTime = static_cast<time_t>(Record[2]);
  Overridden = static_cast<bool>(Record[3]);
  Filename = Blob;
  MaybeAddSystemRootToFilename(F, Filename);
  
  InputFileInfo R = { std::move(Filename), StoredSize, StoredTime, Overridden };
  return R;
}

std::string ASTReader::getInputFileName(ModuleFile &F, unsigned int ID) {
  return readInputFileInfo(F, ID).Filename;
}

InputFile ASTReader::getInputFile(ModuleFile &F, unsigned ID, bool Complain) {
  // If this ID is bogus, just return an empty input file.
  if (ID == 0 || ID > F.InputFilesLoaded.size())
    return InputFile();

  // If we've already loaded this input file, return it.
  if (F.InputFilesLoaded[ID-1].getFile())
    return F.InputFilesLoaded[ID-1];

  if (F.InputFilesLoaded[ID-1].isNotFound())
    return InputFile();

  // Go find this input file.
  BitstreamCursor &Cursor = F.InputFilesCursor;
  SavedStreamPosition SavedPosition(Cursor);
  Cursor.JumpToBit(F.InputFileOffsets[ID-1]);
  
  InputFileInfo FI = readInputFileInfo(F, ID);
  off_t StoredSize = FI.StoredSize;
  time_t StoredTime = FI.StoredTime;
  bool Overridden = FI.Overridden;
  StringRef Filename = FI.Filename;

  const FileEntry *File
    = Overridden? FileMgr.getVirtualFile(Filename, StoredSize, StoredTime)
                : FileMgr.getFile(Filename, /*OpenFile=*/false);

  // If we didn't find the file, resolve it relative to the
  // original directory from which this AST file was created.
  if (File == 0 && !F.OriginalDir.empty() && !CurrentDir.empty() &&
      F.OriginalDir != CurrentDir) {
    std::string Resolved = resolveFileRelativeToOriginalDir(Filename,
                                                            F.OriginalDir,
                                                            CurrentDir);
    if (!Resolved.empty())
      File = FileMgr.getFile(Resolved);
  }

  // For an overridden file, create a virtual file with the stored
  // size/timestamp.
  if (Overridden && File == 0) {
    File = FileMgr.getVirtualFile(Filename, StoredSize, StoredTime);
  }

  if (File == 0) {
    if (Complain) {
      std::string ErrorStr = "could not find file '";
      ErrorStr += Filename;
      ErrorStr += "' referenced by AST file";
      Error(ErrorStr.c_str());
    }
    // Record that we didn't find the file.
    F.InputFilesLoaded[ID-1] = InputFile::getNotFound();
    return InputFile();
  }

  // Check if there was a request to override the contents of the file
  // that was part of the precompiled header. Overridding such a file
  // can lead to problems when lexing using the source locations from the
  // PCH.
  SourceManager &SM = getSourceManager();
  if (!Overridden && SM.isFileOverridden(File)) {
    if (Complain)
      Error(diag::err_fe_pch_file_overridden, Filename);
    // After emitting the diagnostic, recover by disabling the override so
    // that the original file will be used.
    SM.disableFileContentsOverride(File);
    // The FileEntry is a virtual file entry with the size of the contents
    // that would override the original contents. Set it to the original's
    // size/time.
    FileMgr.modifyFileEntry(const_cast<FileEntry*>(File),
                            StoredSize, StoredTime);
  }

  bool IsOutOfDate = false;

  // For an overridden file, there is nothing to validate.
  if (!Overridden && (StoredSize != File->getSize()
#if !defined(LLVM_ON_WIN32)
       // In our regression testing, the Windows file system seems to
       // have inconsistent modification times that sometimes
       // erroneously trigger this error-handling path.
       || StoredTime != File->getModificationTime()
#endif
       )) {
    if (Complain) {
      // Build a list of the PCH imports that got us here (in reverse).
      SmallVector<ModuleFile *, 4> ImportStack(1, &F);
      while (ImportStack.back()->ImportedBy.size() > 0)
        ImportStack.push_back(ImportStack.back()->ImportedBy[0]);

      // The top-level PCH is stale.
      StringRef TopLevelPCHName(ImportStack.back()->FileName);
      Error(diag::err_fe_pch_file_modified, Filename, TopLevelPCHName);

      // Print the import stack.
      if (ImportStack.size() > 1 && !Diags.isDiagnosticInFlight()) {
        Diag(diag::note_pch_required_by)
          << Filename << ImportStack[0]->FileName;
        for (unsigned I = 1; I < ImportStack.size(); ++I)
          Diag(diag::note_pch_required_by)
            << ImportStack[I-1]->FileName << ImportStack[I]->FileName;
      }

      if (!Diags.isDiagnosticInFlight())
        Diag(diag::note_pch_rebuild_required) << TopLevelPCHName;
    }

    IsOutOfDate = true;
  }

  InputFile IF = InputFile(File, Overridden, IsOutOfDate);

  // Note that we've loaded this input file.
  F.InputFilesLoaded[ID-1] = IF;
  return IF;
}

const FileEntry *ASTReader::getFileEntry(StringRef filenameStrRef) {
  ModuleFile &M = ModuleMgr.getPrimaryModule();
  std::string Filename = filenameStrRef;
  MaybeAddSystemRootToFilename(M, Filename);
  const FileEntry *File = FileMgr.getFile(Filename);
  if (File == 0 && !M.OriginalDir.empty() && !CurrentDir.empty() &&
      M.OriginalDir != CurrentDir) {
    std::string resolved = resolveFileRelativeToOriginalDir(Filename,
                                                            M.OriginalDir,
                                                            CurrentDir);
    if (!resolved.empty())
      File = FileMgr.getFile(resolved);
  }

  return File;
}

/// \brief If we are loading a relocatable PCH file, and the filename is
/// not an absolute path, add the system root to the beginning of the file
/// name.
void ASTReader::MaybeAddSystemRootToFilename(ModuleFile &M,
                                             std::string &Filename) {
  // If this is not a relocatable PCH file, there's nothing to do.
  if (!M.RelocatablePCH)
    return;

  if (Filename.empty() || llvm::sys::path::is_absolute(Filename))
    return;

  if (isysroot.empty()) {
    // If no system root was given, default to '/'
    Filename.insert(Filename.begin(), '/');
    return;
  }

  unsigned Length = isysroot.size();
  if (isysroot[Length - 1] != '/')
    Filename.insert(Filename.begin(), '/');

  Filename.insert(Filename.begin(), isysroot.begin(), isysroot.end());
}

ASTReader::ASTReadResult
ASTReader::ReadControlBlock(ModuleFile &F,
                            SmallVectorImpl<ImportedModule> &Loaded,
                            const ModuleFile *ImportedBy,
                            unsigned ClientLoadCapabilities) {
  BitstreamCursor &Stream = F.Stream;

  if (Stream.EnterSubBlock(CONTROL_BLOCK_ID)) {
    Error("malformed block record in AST file");
    return Failure;
  }

  // Read all of the records and blocks in the control block.
  RecordData Record;
  while (1) {
    llvm::BitstreamEntry Entry = Stream.advance();
    
    switch (Entry.Kind) {
    case llvm::BitstreamEntry::Error:
      Error("malformed block record in AST file");
      return Failure;
    case llvm::BitstreamEntry::EndBlock: {
      // Validate input files.
      const HeaderSearchOptions &HSOpts =
          PP.getHeaderSearchInfo().getHeaderSearchOpts();

      // All user input files reside at the index range [0, Record[1]), and
      // system input files reside at [Record[1], Record[0]).
      // Record is the one from INPUT_FILE_OFFSETS.
      unsigned NumInputs = Record[0];
      unsigned NumUserInputs = Record[1];

      if (!DisableValidation &&
          (ValidateSystemInputs || !HSOpts.ModulesValidateOncePerBuildSession ||
           F.InputFilesValidationTimestamp <= HSOpts.BuildSessionTimestamp)) {
        bool Complain = (ClientLoadCapabilities & ARR_OutOfDate) == 0;

        // If we are reading a module, we will create a verification timestamp,
        // so we verify all input files.  Otherwise, verify only user input
        // files.

        unsigned N = NumUserInputs;
        if (ValidateSystemInputs ||
            (HSOpts.ModulesValidateOncePerBuildSession && F.Kind == MK_Module))
          N = NumInputs;

        for (unsigned I = 0; I < N; ++I) {
          InputFile IF = getInputFile(F, I+1, Complain);
          if (!IF.getFile() || IF.isOutOfDate())
            return OutOfDate;
        }
      }

      if (Listener)
        Listener->visitModuleFile(F.FileName);

      if (Listener && Listener->needsInputFileVisitation()) {
        unsigned N = Listener->needsSystemInputFileVisitation() ? NumInputs
                                                                : NumUserInputs;
        for (unsigned I = 0; I < N; ++I) {
          bool IsSystem = I >= NumUserInputs;
          InputFileInfo FI = readInputFileInfo(F, I+1);
          Listener->visitInputFile(FI.Filename, IsSystem, FI.Overridden);
        }
      }

      return Success;
    }

    case llvm::BitstreamEntry::SubBlock:
      switch (Entry.ID) {
      case INPUT_FILES_BLOCK_ID:
        F.InputFilesCursor = Stream;
        if (Stream.SkipBlock() || // Skip with the main cursor
            // Read the abbreviations
            ReadBlockAbbrevs(F.InputFilesCursor, INPUT_FILES_BLOCK_ID)) {
          Error("malformed block record in AST file");
          return Failure;
        }
        continue;
          
      default:
        if (Stream.SkipBlock()) {
          Error("malformed block record in AST file");
          return Failure;
        }
        continue;
      }
      
    case llvm::BitstreamEntry::Record:
      // The interesting case.
      break;
    }

    // Read and process a record.
    Record.clear();
    StringRef Blob;
    switch ((ControlRecordTypes)Stream.readRecord(Entry.ID, Record, &Blob)) {
    case METADATA: {
      if (Record[0] != VERSION_MAJOR && !DisableValidation) {
        if ((ClientLoadCapabilities & ARR_VersionMismatch) == 0)
          Diag(Record[0] < VERSION_MAJOR? diag::err_pch_version_too_old
                                        : diag::err_pch_version_too_new);
        return VersionMismatch;
      }

      bool hasErrors = Record[5];
      if (hasErrors && !DisableValidation && !AllowASTWithCompilerErrors) {
        Diag(diag::err_pch_with_compiler_errors);
        return HadErrors;
      }

      F.RelocatablePCH = Record[4];

      const std::string &CurBranch = getClangFullRepositoryVersion();
      StringRef ASTBranch = Blob;
      if (StringRef(CurBranch) != ASTBranch && !DisableValidation) {
        if ((ClientLoadCapabilities & ARR_VersionMismatch) == 0)
          Diag(diag::err_pch_different_branch) << ASTBranch << CurBranch;
        return VersionMismatch;
      }
      break;
    }

    case IMPORTS: {
      // Load each of the imported PCH files. 
      unsigned Idx = 0, N = Record.size();
      while (Idx < N) {
        // Read information about the AST file.
        ModuleKind ImportedKind = (ModuleKind)Record[Idx++];
        // The import location will be the local one for now; we will adjust
        // all import locations of module imports after the global source
        // location info are setup.
        SourceLocation ImportLoc =
            SourceLocation::getFromRawEncoding(Record[Idx++]);
        off_t StoredSize = (off_t)Record[Idx++];
        time_t StoredModTime = (time_t)Record[Idx++];
        unsigned Length = Record[Idx++];
        SmallString<128> ImportedFile(Record.begin() + Idx,
                                      Record.begin() + Idx + Length);
        Idx += Length;

        // Load the AST file.
        switch(ReadASTCore(ImportedFile, ImportedKind, ImportLoc, &F, Loaded,
                           StoredSize, StoredModTime,
                           ClientLoadCapabilities)) {
        case Failure: return Failure;
          // If we have to ignore the dependency, we'll have to ignore this too.
        case Missing:
        case OutOfDate: return OutOfDate;
        case VersionMismatch: return VersionMismatch;
        case ConfigurationMismatch: return ConfigurationMismatch;
        case HadErrors: return HadErrors;
        case Success: break;
        }
      }
      break;
    }

    case LANGUAGE_OPTIONS: {
      bool Complain = (ClientLoadCapabilities & ARR_ConfigurationMismatch) == 0;
      if (Listener && &F == *ModuleMgr.begin() &&
          ParseLanguageOptions(Record, Complain, *Listener) &&
          !DisableValidation && !AllowConfigurationMismatch)
        return ConfigurationMismatch;
      break;
    }

    case TARGET_OPTIONS: {
      bool Complain = (ClientLoadCapabilities & ARR_ConfigurationMismatch)==0;
      if (Listener && &F == *ModuleMgr.begin() &&
          ParseTargetOptions(Record, Complain, *Listener) &&
          !DisableValidation && !AllowConfigurationMismatch)
        return ConfigurationMismatch;
      break;
    }

    case DIAGNOSTIC_OPTIONS: {
      bool Complain = (ClientLoadCapabilities & ARR_ConfigurationMismatch)==0;
      if (Listener && &F == *ModuleMgr.begin() &&
          ParseDiagnosticOptions(Record, Complain, *Listener) &&
          !DisableValidation && !AllowConfigurationMismatch)
        return ConfigurationMismatch;
      break;
    }

    case FILE_SYSTEM_OPTIONS: {
      bool Complain = (ClientLoadCapabilities & ARR_ConfigurationMismatch)==0;
      if (Listener && &F == *ModuleMgr.begin() &&
          ParseFileSystemOptions(Record, Complain, *Listener) &&
          !DisableValidation && !AllowConfigurationMismatch)
        return ConfigurationMismatch;
      break;
    }

    case HEADER_SEARCH_OPTIONS: {
      bool Complain = (ClientLoadCapabilities & ARR_ConfigurationMismatch)==0;
      if (Listener && &F == *ModuleMgr.begin() &&
          ParseHeaderSearchOptions(Record, Complain, *Listener) &&
          !DisableValidation && !AllowConfigurationMismatch)
        return ConfigurationMismatch;
      break;
    }

    case PREPROCESSOR_OPTIONS: {
      bool Complain = (ClientLoadCapabilities & ARR_ConfigurationMismatch)==0;
      if (Listener && &F == *ModuleMgr.begin() &&
          ParsePreprocessorOptions(Record, Complain, *Listener,
                                   SuggestedPredefines) &&
          !DisableValidation && !AllowConfigurationMismatch)
        return ConfigurationMismatch;
      break;
    }

    case ORIGINAL_FILE:
      F.OriginalSourceFileID = FileID::get(Record[0]);
      F.ActualOriginalSourceFileName = Blob;
      F.OriginalSourceFileName = F.ActualOriginalSourceFileName;
      MaybeAddSystemRootToFilename(F, F.OriginalSourceFileName);
      break;

    case ORIGINAL_FILE_ID:
      F.OriginalSourceFileID = FileID::get(Record[0]);
      break;

    case ORIGINAL_PCH_DIR:
      F.OriginalDir = Blob;
      break;

    case MODULE_NAME:
      F.ModuleName = Blob;
      if (Listener)
        Listener->ReadModuleName(F.ModuleName);
      break;

    case MODULE_MAP_FILE:
      F.ModuleMapPath = Blob;

      // Try to resolve ModuleName in the current header search context and
      // verify that it is found in the same module map file as we saved. If the
      // top-level AST file is a main file, skip this check because there is no
      // usable header search context.
      assert(!F.ModuleName.empty() &&
             "MODULE_NAME should come before MOUDLE_MAP_FILE");
      if (F.Kind == MK_Module &&
          (*ModuleMgr.begin())->Kind != MK_MainFile) {
        Module *M = PP.getHeaderSearchInfo().lookupModule(F.ModuleName);
        if (!M) {
          assert(ImportedBy && "top-level import should be verified");
          if ((ClientLoadCapabilities & ARR_Missing) == 0)
            Diag(diag::err_imported_module_not_found)
              << F.ModuleName << ImportedBy->FileName;
          return Missing;
        }

        const FileEntry *StoredModMap = FileMgr.getFile(F.ModuleMapPath);
        if (StoredModMap == nullptr || StoredModMap != M->ModuleMap) {
          assert(M->ModuleMap && "found module is missing module map file");
          assert(M->Name == F.ModuleName && "found module with different name");
          assert(ImportedBy && "top-level import should be verified");
          if ((ClientLoadCapabilities & ARR_OutOfDate) == 0)
            Diag(diag::err_imported_module_modmap_changed)
              << F.ModuleName << ImportedBy->FileName
              << M->ModuleMap->getName() << F.ModuleMapPath;
          return OutOfDate;
        }
      }

      if (Listener)
        Listener->ReadModuleMapFile(F.ModuleMapPath);
      break;

    case INPUT_FILE_OFFSETS:
      F.InputFileOffsets = (const uint32_t *)Blob.data();
      F.InputFilesLoaded.resize(Record[0]);
      break;
    }
  }
}

ASTReader::ASTReadResult
ASTReader::ReadASTBlock(ModuleFile &F, unsigned ClientLoadCapabilities) {
  BitstreamCursor &Stream = F.Stream;

  if (Stream.EnterSubBlock(AST_BLOCK_ID)) {
    Error("malformed block record in AST file");
    return Failure;
  }

  // Read all of the records and blocks for the AST file.
  RecordData Record;
  while (1) {
    llvm::BitstreamEntry Entry = Stream.advance();
    
    switch (Entry.Kind) {
    case llvm::BitstreamEntry::Error:
      Error("error at end of module block in AST file");
      return Failure;
    case llvm::BitstreamEntry::EndBlock: {
      // Outside of C++, we do not store a lookup map for the translation unit.
      // Instead, mark it as needing a lookup map to be built if this module
      // contains any declarations lexically within it (which it always does!).
      // This usually has no cost, since we very rarely need the lookup map for
      // the translation unit outside C++.
      DeclContext *DC = Context.getTranslationUnitDecl();
      if (DC->hasExternalLexicalStorage() &&
          !getContext().getLangOpts().CPlusPlus)
        DC->setMustBuildLookupTable();
      
      return Success;
    }
    case llvm::BitstreamEntry::SubBlock:
      switch (Entry.ID) {
      case DECLTYPES_BLOCK_ID:
        // We lazily load the decls block, but we want to set up the
        // DeclsCursor cursor to point into it.  Clone our current bitcode
        // cursor to it, enter the block and read the abbrevs in that block.
        // With the main cursor, we just skip over it.
        F.DeclsCursor = Stream;
        if (Stream.SkipBlock() ||  // Skip with the main cursor.
            // Read the abbrevs.
            ReadBlockAbbrevs(F.DeclsCursor, DECLTYPES_BLOCK_ID)) {
          Error("malformed block record in AST file");
          return Failure;
        }
        break;

      case PREPROCESSOR_BLOCK_ID:
        F.MacroCursor = Stream;
        if (!PP.getExternalSource())
          PP.setExternalSource(this);
        
        if (Stream.SkipBlock() ||
            ReadBlockAbbrevs(F.MacroCursor, PREPROCESSOR_BLOCK_ID)) {
          Error("malformed block record in AST file");
          return Failure;
        }
        F.MacroStartOffset = F.MacroCursor.GetCurrentBitNo();
        break;
        
      case PREPROCESSOR_DETAIL_BLOCK_ID:
        F.PreprocessorDetailCursor = Stream;
        if (Stream.SkipBlock() ||
            ReadBlockAbbrevs(F.PreprocessorDetailCursor,
                             PREPROCESSOR_DETAIL_BLOCK_ID)) {
              Error("malformed preprocessor detail record in AST file");
              return Failure;
            }
        F.PreprocessorDetailStartOffset
        = F.PreprocessorDetailCursor.GetCurrentBitNo();
        
        if (!PP.getPreprocessingRecord())
          PP.createPreprocessingRecord();
        if (!PP.getPreprocessingRecord()->getExternalSource())
          PP.getPreprocessingRecord()->SetExternalSource(*this);
        break;
        
      case SOURCE_MANAGER_BLOCK_ID:
        if (ReadSourceManagerBlock(F))
          return Failure;
        break;
        
      case SUBMODULE_BLOCK_ID:
        if (ASTReadResult Result = ReadSubmoduleBlock(F, ClientLoadCapabilities))
          return Result;
        break;
        
      case COMMENTS_BLOCK_ID: {
        BitstreamCursor C = Stream;
        if (Stream.SkipBlock() ||
            ReadBlockAbbrevs(C, COMMENTS_BLOCK_ID)) {
          Error("malformed comments block in AST file");
          return Failure;
        }
        CommentsCursors.push_back(std::make_pair(C, &F));
        break;
      }
        
      default:
        if (Stream.SkipBlock()) {
          Error("malformed block record in AST file");
          return Failure;
        }
        break;
      }
      continue;
    
    case llvm::BitstreamEntry::Record:
      // The interesting case.
      break;
    }

    // Read and process a record.
    Record.clear();
    StringRef Blob;
    switch ((ASTRecordTypes)Stream.readRecord(Entry.ID, Record, &Blob)) {
    default:  // Default behavior: ignore.
      break;

    case TYPE_OFFSET: {
      if (F.LocalNumTypes != 0) {
        Error("duplicate TYPE_OFFSET record in AST file");
        return Failure;
      }
      F.TypeOffsets = (const uint32_t *)Blob.data();
      F.LocalNumTypes = Record[0];
      unsigned LocalBaseTypeIndex = Record[1];
      F.BaseTypeIndex = getTotalNumTypes();
        
      if (F.LocalNumTypes > 0) {
        // Introduce the global -> local mapping for types within this module.
        GlobalTypeMap.insert(std::make_pair(getTotalNumTypes(), &F));
        
        // Introduce the local -> global mapping for types within this module.
        F.TypeRemap.insertOrReplace(
          std::make_pair(LocalBaseTypeIndex, 
                         F.BaseTypeIndex - LocalBaseTypeIndex));
        
        TypesLoaded.resize(TypesLoaded.size() + F.LocalNumTypes);
      }
      break;
    }
        
    case DECL_OFFSET: {
      if (F.LocalNumDecls != 0) {
        Error("duplicate DECL_OFFSET record in AST file");
        return Failure;
      }
      F.DeclOffsets = (const DeclOffset *)Blob.data();
      F.LocalNumDecls = Record[0];
      unsigned LocalBaseDeclID = Record[1];
      F.BaseDeclID = getTotalNumDecls();
        
      if (F.LocalNumDecls > 0) {
        // Introduce the global -> local mapping for declarations within this 
        // module.
        GlobalDeclMap.insert(
          std::make_pair(getTotalNumDecls() + NUM_PREDEF_DECL_IDS, &F));
        
        // Introduce the local -> global mapping for declarations within this
        // module.
        F.DeclRemap.insertOrReplace(
          std::make_pair(LocalBaseDeclID, F.BaseDeclID - LocalBaseDeclID));
        
        // Introduce the global -> local mapping for declarations within this
        // module.
        F.GlobalToLocalDeclIDs[&F] = LocalBaseDeclID;
        
        DeclsLoaded.resize(DeclsLoaded.size() + F.LocalNumDecls);
      }
      break;
    }
        
    case TU_UPDATE_LEXICAL: {
      DeclContext *TU = Context.getTranslationUnitDecl();
      DeclContextInfo &Info = F.DeclContextInfos[TU];
      Info.LexicalDecls = reinterpret_cast<const KindDeclIDPair *>(Blob.data());
      Info.NumLexicalDecls 
        = static_cast<unsigned int>(Blob.size() / sizeof(KindDeclIDPair));
      TU->setHasExternalLexicalStorage(true);
      break;
    }

    case UPDATE_VISIBLE: {
      unsigned Idx = 0;
      serialization::DeclID ID = ReadDeclID(F, Record, Idx);
      ASTDeclContextNameLookupTable *Table =
          ASTDeclContextNameLookupTable::Create(
              (const unsigned char *)Blob.data() + Record[Idx++],
              (const unsigned char *)Blob.data() + sizeof(uint32_t),
              (const unsigned char *)Blob.data(),
              ASTDeclContextNameLookupTrait(*this, F));
      if (Decl *D = GetExistingDecl(ID)) {
        auto *DC = cast<DeclContext>(D);
        DC->getPrimaryContext()->setHasExternalVisibleStorage(true);
        auto *&LookupTable = F.DeclContextInfos[DC].NameLookupTableData;
        // FIXME: There should never be an existing lookup table.
        delete LookupTable;
        LookupTable = Table;
      } else
        PendingVisibleUpdates[ID].push_back(std::make_pair(Table, &F));
      break;
    }

    case IDENTIFIER_TABLE:
      F.IdentifierTableData = Blob.data();
      if (Record[0]) {
        F.IdentifierLookupTable = ASTIdentifierLookupTable::Create(
            (const unsigned char *)F.IdentifierTableData + Record[0],
            (const unsigned char *)F.IdentifierTableData + sizeof(uint32_t),
            (const unsigned char *)F.IdentifierTableData,
            ASTIdentifierLookupTrait(*this, F));
        
        PP.getIdentifierTable().setExternalIdentifierLookup(this);
      }
      break;

    case IDENTIFIER_OFFSET: {
      if (F.LocalNumIdentifiers != 0) {
        Error("duplicate IDENTIFIER_OFFSET record in AST file");
        return Failure;
      }
      F.IdentifierOffsets = (const uint32_t *)Blob.data();
      F.LocalNumIdentifiers = Record[0];
      unsigned LocalBaseIdentifierID = Record[1];
      F.BaseIdentifierID = getTotalNumIdentifiers();
        
      if (F.LocalNumIdentifiers > 0) {
        // Introduce the global -> local mapping for identifiers within this
        // module.
        GlobalIdentifierMap.insert(std::make_pair(getTotalNumIdentifiers() + 1, 
                                                  &F));
        
        // Introduce the local -> global mapping for identifiers within this
        // module.
        F.IdentifierRemap.insertOrReplace(
          std::make_pair(LocalBaseIdentifierID,
                         F.BaseIdentifierID - LocalBaseIdentifierID));
        
        IdentifiersLoaded.resize(IdentifiersLoaded.size() 
                                 + F.LocalNumIdentifiers);
      }
      break;
    }

    case EAGERLY_DESERIALIZED_DECLS:
      for (unsigned I = 0, N = Record.size(); I != N; ++I)
        EagerlyDeserializedDecls.push_back(getGlobalDeclID(F, Record[I]));
      break;

    case SPECIAL_TYPES:
      if (SpecialTypes.empty()) {
        for (unsigned I = 0, N = Record.size(); I != N; ++I)
          SpecialTypes.push_back(getGlobalTypeID(F, Record[I]));
        break;
      }

      if (SpecialTypes.size() != Record.size()) {
        Error("invalid special-types record");
        return Failure;
      }

      for (unsigned I = 0, N = Record.size(); I != N; ++I) {
        serialization::TypeID ID = getGlobalTypeID(F, Record[I]);
        if (!SpecialTypes[I])
          SpecialTypes[I] = ID;
        // FIXME: If ID && SpecialTypes[I] != ID, do we need a separate
        // merge step?
      }
      break;

    case STATISTICS:
      TotalNumStatements += Record[0];
      TotalNumMacros += Record[1];
      TotalLexicalDeclContexts += Record[2];
      TotalVisibleDeclContexts += Record[3];
      break;

    case UNUSED_FILESCOPED_DECLS:
      for (unsigned I = 0, N = Record.size(); I != N; ++I)
        UnusedFileScopedDecls.push_back(getGlobalDeclID(F, Record[I]));
      break;

    case DELEGATING_CTORS:
      for (unsigned I = 0, N = Record.size(); I != N; ++I)
        DelegatingCtorDecls.push_back(getGlobalDeclID(F, Record[I]));
      break;

    case WEAK_UNDECLARED_IDENTIFIERS:
      if (Record.size() % 4 != 0) {
        Error("invalid weak identifiers record");
        return Failure;
      }
        
      // FIXME: Ignore weak undeclared identifiers from non-original PCH 
      // files. This isn't the way to do it :)
      WeakUndeclaredIdentifiers.clear();
        
      // Translate the weak, undeclared identifiers into global IDs.
      for (unsigned I = 0, N = Record.size(); I < N; /* in loop */) {
        WeakUndeclaredIdentifiers.push_back(
          getGlobalIdentifierID(F, Record[I++]));
        WeakUndeclaredIdentifiers.push_back(
          getGlobalIdentifierID(F, Record[I++]));
        WeakUndeclaredIdentifiers.push_back(
          ReadSourceLocation(F,