1 files changed, 853 insertions, 0 deletions
diff --git a/contrib/llvm/tools/clang/lib/Serialization/GlobalModuleIndex.cpp b/contrib/llvm/tools/clang/lib/Serialization/GlobalModuleIndex.cpp
new file mode 100644
index 000000000000..fb647b0be9bc
--- /dev/null
+++ b/contrib/llvm/tools/clang/lib/Serialization/GlobalModuleIndex.cpp
@@ -0,0 +1,853 @@
+//===--- GlobalModuleIndex.cpp - Global Module Index ------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the GlobalModuleIndex class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ASTReaderInternals.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/OnDiskHashTable.h"
+#include "clang/Serialization/ASTBitCodes.h"
+#include "clang/Serialization/GlobalModuleIndex.h"
+#include "clang/Serialization/Module.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/MapVector.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Bitcode/BitstreamReader.h"
+#include "llvm/Bitcode/BitstreamWriter.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/LockFileManager.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
+#include <cstdio>
+using namespace clang;
+using namespace serialization;
+
+//----------------------------------------------------------------------------//
+// Shared constants
+//----------------------------------------------------------------------------//
+namespace {
+  enum {
+    /// \brief The block containing the index.
+    GLOBAL_INDEX_BLOCK_ID = llvm::bitc::FIRST_APPLICATION_BLOCKID
+  };
+
+  /// \brief Describes the record types in the index.
+  enum IndexRecordTypes {
+    /// \brief Contains version information and potentially other metadata,
+    /// used to determine if we can read this global index file.
+    INDEX_METADATA,
+    /// \brief Describes a module, including its file name and dependencies.
+    MODULE,
+    /// \brief The index for identifiers.
+    IDENTIFIER_INDEX
+  };
+}
+
+/// \brief The name of the global index file.
+static const char * const IndexFileName = "modules.idx";
+
+/// \brief The global index file version.
+static const unsigned CurrentVersion = 1;
+
+//----------------------------------------------------------------------------//
+// Global module index reader.
+//----------------------------------------------------------------------------//
+
+namespace {
+
+/// \brief Trait used to read the identifier index from the on-disk hash
+/// table.
+class IdentifierIndexReaderTrait {
+public:
+  typedef StringRef external_key_type;
+  typedef StringRef internal_key_type;
+  typedef SmallVector<unsigned, 2> data_type;
+
+  static bool EqualKey(const internal_key_type& a, const internal_key_type& b) {
+    return a == b;
+  }
+
+  static unsigned ComputeHash(const internal_key_type& a) {
+    return llvm::HashString(a);
+  }
+
+  static std::pair<unsigned, unsigned>
+  ReadKeyDataLength(const unsigned char*& d) {
+    using namespace clang::io;
+    unsigned KeyLen = ReadUnalignedLE16(d);
+    unsigned DataLen = ReadUnalignedLE16(d);
+    return std::make_pair(KeyLen, DataLen);
+  }
+
+  static const internal_key_type&
+  GetInternalKey(const external_key_type& x) { return x; }
+
+  static const external_key_type&
+  GetExternalKey(const internal_key_type& x) { return x; }
+
+  static internal_key_type ReadKey(const unsigned char* d, unsigned n) {
+    return StringRef((const char *)d, n);
+  }
+
+  static data_type ReadData(const internal_key_type& k,
+                            const unsigned char* d,
+                            unsigned DataLen) {
+    using namespace clang::io;
+
+    data_type Result;
+    while (DataLen > 0) {
+      unsigned ID = ReadUnalignedLE32(d);
+      Result.push_back(ID);
+      DataLen -= 4;
+    }
+
+    return Result;
+  }
+};
+
+typedef OnDiskChainedHashTable<IdentifierIndexReaderTrait> IdentifierIndexTable;
+
+}
+
+GlobalModuleIndex::GlobalModuleIndex(llvm::MemoryBuffer *Buffer,
+                                     llvm::BitstreamCursor Cursor)
+  : Buffer(Buffer), IdentifierIndex(),
+    NumIdentifierLookups(), NumIdentifierLookupHits()
+{
+  // Read the global index.
+  bool InGlobalIndexBlock = false;
+  bool Done = false;
+  while (!Done) {
+    llvm::BitstreamEntry Entry = Cursor.advance();
+
+    switch (Entry.Kind) {
+    case llvm::BitstreamEntry::Error:
+      return;
+
+    case llvm::BitstreamEntry::EndBlock:
+      if (InGlobalIndexBlock) {
+        InGlobalIndexBlock = false;
+        Done = true;
+        continue;
+      }
+      return;
+
+
+    case llvm::BitstreamEntry::Record:
+      // Entries in the global index block are handled below.
+      if (InGlobalIndexBlock)
+        break;
+
+      return;
+
+    case llvm::BitstreamEntry::SubBlock:
+      if (!InGlobalIndexBlock && Entry.ID == GLOBAL_INDEX_BLOCK_ID) {
+        if (Cursor.EnterSubBlock(GLOBAL_INDEX_BLOCK_ID))
+          return;
+
+        InGlobalIndexBlock = true;
+      } else if (Cursor.SkipBlock()) {
+        return;
+      }
+      continue;
+    }
+
+    SmallVector<uint64_t, 64> Record;
+    StringRef Blob;
+    switch ((IndexRecordTypes)Cursor.readRecord(Entry.ID, Record, &Blob)) {
+    case INDEX_METADATA:
+      // Make sure that the version matches.
+      if (Record.size() < 1 || Record[0] != CurrentVersion)
+        return;
+      break;
+
+    case MODULE: {
+      unsigned Idx = 0;
+      unsigned ID = Record[Idx++];
+
+      // Make room for this module's information.
+      if (ID == Modules.size())
+        Modules.push_back(ModuleInfo());
+      else
+        Modules.resize(ID + 1);
+
+      // Size/modification time for this module file at the time the
+      // global index was built.
+      Modules[ID].Size = Record[Idx++];
+      Modules[ID].ModTime = Record[Idx++];
+
+      // File name.
+      unsigned NameLen = Record[Idx++];
+      Modules[ID].FileName.assign(Record.begin() + Idx,
+                                  Record.begin() + Idx + NameLen);
+      Idx += NameLen;
+
+      // Dependencies
+      unsigned NumDeps = Record[Idx++];
+      Modules[ID].Dependencies.insert(Modules[ID].Dependencies.end(),
+                                      Record.begin() + Idx,
+                                      Record.begin() + Idx + NumDeps);
+      Idx += NumDeps;
+
+      // Make sure we're at the end of the record.
+      assert(Idx == Record.size() && "More module info?");
+
+      // Record this module as an unresolved module.
+      UnresolvedModules[llvm::sys::path::stem(Modules[ID].FileName)] = ID;
+      break;
+    }
+
+    case IDENTIFIER_INDEX:
+      // Wire up the identifier index.
+      if (Record[0]) {
+        IdentifierIndex = IdentifierIndexTable::Create(
+                            (const unsigned char *)Blob.data() + Record[0],
+                            (const unsigned char *)Blob.data(),
+                            IdentifierIndexReaderTrait());
+      }
+      break;
+    }
+  }
+}
+
+GlobalModuleIndex::~GlobalModuleIndex() { }
+
+std::pair<GlobalModuleIndex *, GlobalModuleIndex::ErrorCode>
+GlobalModuleIndex::readIndex(StringRef Path) {
+  // Load the index file, if it's there.
+  llvm::SmallString<128> IndexPath;
+  IndexPath += Path;
+  llvm::sys::path::append(IndexPath, IndexFileName);
+
+  llvm::OwningPtr<llvm::MemoryBuffer> Buffer;
+  if (llvm::MemoryBuffer::getFile(IndexPath.c_str(), Buffer) !=
+      llvm::errc::success)
+    return std::make_pair((GlobalModuleIndex *)0, EC_NotFound);
+
+  /// \brief The bitstream reader from which we'll read the AST file.
+  llvm::BitstreamReader Reader((const unsigned char *)Buffer->getBufferStart(),
+                               (const unsigned char *)Buffer->getBufferEnd());
+
+  /// \brief The main bitstream cursor for the main block.
+  llvm::BitstreamCursor Cursor(Reader);
+
+  // Sniff for the signature.
+  if (Cursor.Read(8) != 'B' ||
+      Cursor.Read(8) != 'C' ||
+      Cursor.Read(8) != 'G' ||
+      Cursor.Read(8) != 'I') {
+    return std::make_pair((GlobalModuleIndex *)0, EC_IOError);
+  }
+  
+  return std::make_pair(new GlobalModuleIndex(Buffer.take(), Cursor), EC_None);
+}
+
+void
+GlobalModuleIndex::getKnownModules(SmallVectorImpl<ModuleFile *> &ModuleFiles) {
+  ModuleFiles.clear();
+  for (unsigned I = 0, N = Modules.size(); I != N; ++I) {
+    if (ModuleFile *MF = Modules[I].File)
+      ModuleFiles.push_back(MF);
+  }
+}
+
+void GlobalModuleIndex::getModuleDependencies(
+       ModuleFile *File,
+       SmallVectorImpl<ModuleFile *> &Dependencies) {
+  // Look for information about this module file.
+  llvm::DenseMap<ModuleFile *, unsigned>::iterator Known
+    = ModulesByFile.find(File);
+  if (Known == ModulesByFile.end())
+    return;
+
+  // Record dependencies.
+  Dependencies.clear();
+  ArrayRef<unsigned> StoredDependencies = Modules[Known->second].Dependencies;
+  for (unsigned I = 0, N = StoredDependencies.size(); I != N; ++I) {
+    if (ModuleFile *MF = Modules[I].File)
+      Dependencies.push_back(MF);
+  }
+}
+
+bool GlobalModuleIndex::lookupIdentifier(StringRef Name, HitSet &Hits) {
+  Hits.clear();
+  
+  // If there's no identifier index, there is nothing we can do.
+  if (!IdentifierIndex)
+    return false;
+
+  // Look into the identifier index.
+  ++NumIdentifierLookups;
+  IdentifierIndexTable &Table
+    = *static_cast<IdentifierIndexTable *>(IdentifierIndex);
+  IdentifierIndexTable::iterator Known = Table.find(Name);
+  if (Known == Table.end()) {
+    return true;
+  }
+
+  SmallVector<unsigned, 2> ModuleIDs = *Known;
+  for (unsigned I = 0, N = ModuleIDs.size(); I != N; ++I) {
+    if (ModuleFile *MF = Modules[ModuleIDs[I]].File)
+      Hits.insert(MF);
+  }
+
+  ++NumIdentifierLookupHits;
+  return true;
+}
+
+bool GlobalModuleIndex::loadedModuleFile(ModuleFile *File) {
+  // Look for the module in the global module index based on the module name.
+  StringRef Name = llvm::sys::path::stem(File->FileName);
+  llvm::StringMap<unsigned>::iterator Known = UnresolvedModules.find(Name);
+  if (Known == UnresolvedModules.end()) {
+    return true;
+  }
+
+  // Rectify this module with the global module index.
+  ModuleInfo &Info = Modules[Known->second];
+
+  //  If the size and modification time match what we expected, record this
+  // module file.
+  bool Failed = true;
+  if (File->File->getSize() == Info.Size &&
+      File->File->getModificationTime() == Info.ModTime) {
+    Info.File = File;
+    ModulesByFile[File] = Known->second;
+
+    Failed = false;
+  }
+
+  // One way or another, we have resolved this module file.
+  UnresolvedModules.erase(Known);
+  return Failed;
+}
+
+void GlobalModuleIndex::printStats() {
+  std::fprintf(stderr, "*** Global Module Index Statistics:\n");
+  if (NumIdentifierLookups) {
+    fprintf(stderr, "  %u / %u identifier lookups succeeded (%f%%)\n",
+            NumIdentifierLookupHits, NumIdentifierLookups,
+            (double)NumIdentifierLookupHits*100.0/NumIdentifierLookups);
+  }
+  std::fprintf(stderr, "\n");
+}
+
+//----------------------------------------------------------------------------//
+// Global module index writer.
+//----------------------------------------------------------------------------//
+
+namespace {
+  /// \brief Provides information about a specific module file.
+  struct ModuleFileInfo {
+    /// \brief The numberic ID for this module file.
+    unsigned ID;
+
+    /// \brief The set of modules on which this module depends. Each entry is
+    /// a module ID.
+    SmallVector<unsigned, 4> Dependencies;
+  };
+
+  /// \brief Builder that generates the global module index file.
+  class GlobalModuleIndexBuilder {
+    FileManager &FileMgr;
+
+    /// \brief Mapping from files to module file information.
+    typedef llvm::MapVector<const FileEntry *, ModuleFileInfo> ModuleFilesMap;
+
+    /// \brief Information about each of the known module files.
+    ModuleFilesMap ModuleFiles;
+
+    /// \brief Mapping from identifiers to the list of module file IDs that
+    /// consider this identifier to be interesting.
+    typedef llvm::StringMap<SmallVector<unsigned, 2> > InterestingIdentifierMap;
+
+    /// \brief A mapping from all interesting identifiers to the set of module
+    /// files in which those identifiers are considered interesting.
+    InterestingIdentifierMap InterestingIdentifiers;
+    
+    /// \brief Write the block-info block for the global module index file.
+    void emitBlockInfoBlock(llvm::BitstreamWriter &Stream);
+
+    /// \brief Retrieve the module file information for the given file.
+    ModuleFileInfo &getModuleFileInfo(const FileEntry *File) {
+      llvm::MapVector<const FileEntry *, ModuleFileInfo>::iterator Known
+        = ModuleFiles.find(File);
+      if (Known != ModuleFiles.end())
+        return Known->second;
+
+      unsigned NewID = ModuleFiles.size();
+      ModuleFileInfo &Info = ModuleFiles[File];
+      Info.ID = NewID;
+      return Info;
+    }
+
+  public:
+    explicit GlobalModuleIndexBuilder(FileManager &FileMgr) : FileMgr(FileMgr){}
+
+    /// \brief Load the contents of the given module file into the builder.
+    ///
+    /// \returns true if an error occurred, false otherwise.
+    bool loadModuleFile(const FileEntry *File);
+
+    /// \brief Write the index to the given bitstream.
+    void writeIndex(llvm::BitstreamWriter &Stream);
+  };
+}
+
+static void emitBlockID(unsigned ID, const char *Name,
+                        llvm::BitstreamWriter &Stream,
+                        SmallVectorImpl<uint64_t> &Record) {
+  Record.clear();
+  Record.push_back(ID);
+  Stream.EmitRecord(llvm::bitc::BLOCKINFO_CODE_SETBID, Record);
+
+  // Emit the block name if present.
+  if (Name == 0 || Name[0] == 0) return;
+  Record.clear();
+  while (*Name)
+    Record.push_back(*Name++);
+  Stream.EmitRecord(llvm::bitc::BLOCKINFO_CODE_BLOCKNAME, Record);
+}
+
+static void emitRecordID(unsigned ID, const char *Name,
+                         llvm::BitstreamWriter &Stream,
+                         SmallVectorImpl<uint64_t> &Record) {
+  Record.clear();
+  Record.push_back(ID);
+  while (*Name)
+    Record.push_back(*Name++);
+  Stream.EmitRecord(llvm::bitc::BLOCKINFO_CODE_SETRECORDNAME, Record);
+}
+
+void
+GlobalModuleIndexBuilder::emitBlockInfoBlock(llvm::BitstreamWriter &Stream) {
+  SmallVector<uint64_t, 64> Record;
+  Stream.EnterSubblock(llvm::bitc::BLOCKINFO_BLOCK_ID, 3);
+
+#define BLOCK(X) emitBlockID(X ## _ID, #X, Stream, Record)
+#define RECORD(X) emitRecordID(X, #X, Stream, Record)
+  BLOCK(GLOBAL_INDEX_BLOCK);
+  RECORD(INDEX_METADATA);
+  RECORD(MODULE);
+  RECORD(IDENTIFIER_INDEX);
+#undef RECORD
+#undef BLOCK
+
+  Stream.ExitBlock();
+}
+
+namespace {
+  class InterestingASTIdentifierLookupTrait
+    : public serialization::reader::ASTIdentifierLookupTraitBase {
+
+  public:
+    /// \brief The identifier and whether it is "interesting".
+    typedef std::pair<StringRef, bool> data_type;
+
+    data_type ReadData(const internal_key_type& k,
+                       const unsigned char* d,
+                       unsigned DataLen) {
+      // The first bit indicates whether this identifier is interesting.
+      // That's all we care about.
+      using namespace clang::io;
+      unsigned RawID = ReadUnalignedLE32(d);
+      bool IsInteresting = RawID & 0x01;
+      return std::make_pair(k, IsInteresting);
+    }
+  };
+}
+
+bool GlobalModuleIndexBuilder::loadModuleFile(const FileEntry *File) {
+  // Open the module file.
+  OwningPtr<llvm::MemoryBuffer> Buffer;
+  std::string ErrorStr;
+  Buffer.reset(FileMgr.getBufferForFile(File, &ErrorStr, /*isVolatile=*/true));
+  if (!Buffer) {
+    return true;
+  }
+
+  // Initialize the input stream
+  llvm::BitstreamReader InStreamFile;
+  llvm::BitstreamCursor InStream;
+  InStreamFile.init((const unsigned char *)Buffer->getBufferStart(),
+                  (const unsigned char *)Buffer->getBufferEnd());
+  InStream.init(InStreamFile);
+
+  // Sniff for the signature.
+  if (InStream.Read(8) != 'C' ||
+      InStream.Read(8) != 'P' ||
+      InStream.Read(8) != 'C' ||
+      InStream.Read(8) != 'H') {
+    return true;
+  }
+
+  // Record this module file and assign it a unique ID (if it doesn't have
+  // one already).
+  unsigned ID = getModuleFileInfo(File).ID;
+
+  // Search for the blocks and records we care about.
+  enum { Other, ControlBlock, ASTBlock } State = Other;
+  bool Done = false;
+  while (!Done) {
+    llvm::BitstreamEntry Entry = InStream.advance();
+    switch (Entry.Kind) {
+    case llvm::BitstreamEntry::Error:
+      Done = true;
+      continue;
+
+    case llvm::BitstreamEntry::Record:
+      // In the 'other' state, just skip the record. We don't care.
+      if (State == Other) {
+        InStream.skipRecord(Entry.ID);
+        continue;
+      }
+
+      // Handle potentially-interesting records below.
+      break;
+
+    case llvm::BitstreamEntry::SubBlock:
+      if (Entry.ID == CONTROL_BLOCK_ID) {
+        if (InStream.EnterSubBlock(CONTROL_BLOCK_ID))
+          return true;
+
+        // Found the control block.
+        State = ControlBlock;
+        continue;
+      }
+
+      if (Entry.ID == AST_BLOCK_ID) {
+        if (InStream.EnterSubBlock(AST_BLOCK_ID))
+          return true;
+
+        // Found the AST block.
+        State = ASTBlock;
+        continue;
+      }
+
+      if (InStream.SkipBlock())
+        return true;
+
+      continue;
+
+    case llvm::BitstreamEntry::EndBlock:
+      State = Other;
+      continue;
+    }
+
+    // Read the given record.
+    SmallVector<uint64_t, 64> Record;
+    StringRef Blob;
+    unsigned Code = InStream.readRecord(Entry.ID, Record, &Blob);
+
+    // Handle module dependencies.
+    if (State == ControlBlock && Code == IMPORTS) {
+      // Load each of the imported PCH files.
+      unsigned Idx = 0, N = Record.size();
+      while (Idx < N) {
+        // Read information about the AST file.
+
+        // Skip the imported kind
+        ++Idx;
+
+        // Skip the import location
+        ++Idx;
+
+        // Load stored size/modification time. 
+        off_t StoredSize = (off_t)Record[Idx++];
+        time_t StoredModTime = (time_t)Record[Idx++];
+
+        // Retrieve the imported file name.
+        unsigned Length = Record[Idx++];
+        SmallString<128> ImportedFile(Record.begin() + Idx,
+                                      Record.begin() + Idx + Length);
+        Idx += Length;
+
+        // Find the imported module file.
+        const FileEntry *DependsOnFile
+          = FileMgr.getFile(ImportedFile, /*openFile=*/false,
+                            /*cacheFailure=*/false);
+        if (!DependsOnFile ||
+            (StoredSize != DependsOnFile->getSize()) ||
+            (StoredModTime != DependsOnFile->getModificationTime()))
+          return true;
+
+        // Record the dependency.
+        unsigned DependsOnID = getModuleFileInfo(DependsOnFile).ID;
+        getModuleFileInfo(File).Dependencies.push_back(DependsOnID);
+      }
+
+      continue;
+    }
+
+    // Handle the identifier table
+    if (State == ASTBlock && Code == IDENTIFIER_TABLE && Record[0] > 0) {
+      typedef OnDiskChainedHashTable<InterestingASTIdentifierLookupTrait>
+        InterestingIdentifierTable;
+      llvm::OwningPtr<InterestingIdentifierTable>
+        Table(InterestingIdentifierTable::Create(
+                (const unsigned char *)Blob.data() + Record[0],
+                (const unsigned char *)Blob.data()));
+      for (InterestingIdentifierTable::data_iterator D = Table->data_begin(),
+                                                     DEnd = Table->data_end();
+           D != DEnd; ++D) {
+        std::pair<StringRef, bool> Ident = *D;
+        if (Ident.second)
+          InterestingIdentifiers[Ident.first].push_back(ID);
+        else
+          (void)InterestingIdentifiers[Ident.first];
+      }
+    }
+
+    // We don't care about this record.
+  }
+
+  return false;
+}
+
+namespace {
+
+/// \brief Trait used to generate the identifier index as an on-disk hash
+/// table.
+class IdentifierIndexWriterTrait {
+public:
+  typedef StringRef key_type;
+  typedef StringRef key_type_ref;
+  typedef SmallVector<unsigned, 2> data_type;
+  typedef const SmallVector<unsigned, 2> &data_type_ref;
+
+  static unsigned ComputeHash(key_type_ref Key) {
+    return llvm::HashString(Key);
+  }
+
+  std::pair<unsigned,unsigned>
+  EmitKeyDataLength(raw_ostream& Out, key_type_ref Key, data_type_ref Data) {
+    unsigned KeyLen = Key.size();
+    unsigned DataLen = Data.size() * 4;
+    clang::io::Emit16(Out, KeyLen);
+    clang::io::Emit16(Out, DataLen);
+    return std::make_pair(KeyLen, DataLen);
+  }
+  
+  void EmitKey(raw_ostream& Out, key_type_ref Key, unsigned KeyLen) {
+    Out.write(Key.data(), KeyLen);
+  }
+
+  void EmitData(raw_ostream& Out, key_type_ref Key, data_type_ref Data,
+                unsigned DataLen) {
+    for (unsigned I = 0, N = Data.size(); I != N; ++I)
+      clang::io::Emit32(Out, Data[I]);
+  }
+};
+
+}
+
+void GlobalModuleIndexBuilder::writeIndex(llvm::BitstreamWriter &Stream) {
+  using namespace llvm;
+  
+  // Emit the file header.
+  Stream.Emit((unsigned)'B', 8);
+  Stream.Emit((unsigned)'C', 8);
+  Stream.Emit((unsigned)'G', 8);
+  Stream.Emit((unsigned)'I', 8);
+
+  // Write the block-info block, which describes the records in this bitcode
+  // file.
+  emitBlockInfoBlock(Stream);
+
+  Stream.EnterSubblock(GLOBAL_INDEX_BLOCK_ID, 3);
+
+  // Write the metadata.
+  SmallVector<uint64_t, 2> Record;
+  Record.push_back(CurrentVersion);
+  Stream.EmitRecord(INDEX_METADATA, Record);
+
+  // Write the set of known module files.
+  for (ModuleFilesMap::iterator M = ModuleFiles.begin(),
+                                MEnd = ModuleFiles.end();
+       M != MEnd; ++M) {
+    Record.clear();
+    Record.push_back(M->second.ID);
+    Record.push_back(M->first->getSize());
+    Record.push_back(M->first->getModificationTime());
+
+    // File name
+    StringRef Name(M->first->getName());
+    Record.push_back(Name.size());
+    Record.append(Name.begin(), Name.end());
+
+    // Dependencies
+    Record.push_back(M->second.Dependencies.size());
+    Record.append(M->second.Dependencies.begin(), M->second.Dependencies.end());
+    Stream.EmitRecord(MODULE, Record);
+  }
+
+  // Write the identifier -> module file mapping.
+  {
+    OnDiskChainedHashTableGenerator<IdentifierIndexWriterTrait> Generator;
+    IdentifierIndexWriterTrait Trait;
+
+    // Populate the hash table.
+    for (InterestingIdentifierMap::iterator I = InterestingIdentifiers.begin(),
+                                            IEnd = InterestingIdentifiers.end();
+         I != IEnd; ++I) {
+      Generator.insert(I->first(), I->second, Trait);
+    }
+    
+    // Create the on-disk hash table in a buffer.
+    SmallString<4096> IdentifierTable;
+    uint32_t BucketOffset;
+    {
+      llvm::raw_svector_ostream Out(IdentifierTable);
+      // Make sure that no bucket is at offset 0
+      clang::io::Emit32(Out, 0);
+      BucketOffset = Generator.Emit(Out, Trait);
+    }
+
+    // Create a blob abbreviation
+    BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
+    Abbrev->Add(BitCodeAbbrevOp(IDENTIFIER_INDEX));
+    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
+    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
+    unsigned IDTableAbbrev = Stream.EmitAbbrev(Abbrev);
+
+    // Write the identifier table
+    Record.clear();
+    Record.push_back(IDENTIFIER_INDEX);
+    Record.push_back(BucketOffset);
+    Stream.EmitRecordWithBlob(IDTableAbbrev, Record, IdentifierTable.str());
+  }
+
+  Stream.ExitBlock();
+}
+
+GlobalModuleIndex::ErrorCode
+GlobalModuleIndex::writeIndex(FileManager &FileMgr, StringRef Path) {
+  llvm::SmallString<128> IndexPath;
+  IndexPath += Path;
+  llvm::sys::path::append(IndexPath, IndexFileName);
+
+  // Coordinate building the global index file with other processes that might
+  // try to do the same.
+  llvm::LockFileManager Locked(IndexPath);
+  switch (Locked) {
+  case llvm::LockFileManager::LFS_Error:
+    return EC_IOError;
+
+  case llvm::LockFileManager::LFS_Owned:
+    // We're responsible for building the index ourselves. Do so below.
+    break;
+
+  case llvm::LockFileManager::LFS_Shared:
+    // Someone else is responsible for building the index. We don't care
+    // when they finish, so we're done.
+    return EC_Building;
+  }
+
+  // The module index builder.
+  GlobalModuleIndexBuilder Builder(FileMgr);
+  
+  // Load each of the module files.
+  llvm::error_code EC;
+  for (llvm::sys::fs::directory_iterator D(Path, EC), DEnd;
+       D != DEnd && !EC;
+       D.increment(EC)) {
+    // If this isn't a module file, we don't care.
+    if (llvm::sys::path::extension(D->path()) != ".pcm") {
+      // ... unless it's a .pcm.lock file, which indicates that someone is
+      // in the process of rebuilding a module. They'll rebuild the index
+      // at the end of that translation unit, so we don't have to.
+      if (llvm::sys::path::extension(D->path()) == ".pcm.lock")
+        return EC_Building;
+
+      continue;
+    }
+
+    // If we can't find the module file, skip it.
+    const FileEntry *ModuleFile = FileMgr.getFile(D->path());
+    if (!ModuleFile)
+      continue;
+
+    // Load this module file.
+    if (Builder.loadModuleFile(ModuleFile))
+      return EC_IOError;
+  }
+
+  // The output buffer, into which the global index will be written.
+  SmallVector<char, 16> OutputBuffer;
+  {
+    llvm::BitstreamWriter OutputStream(OutputBuffer);
+    Builder.writeIndex(OutputStream);
+  }
+
+  // Write the global index file to a temporary file.
+  llvm::SmallString<128> IndexTmpPath;
+  int TmpFD;
+  if (llvm::sys::fs::createUniqueFile(IndexPath + "-%%%%%%%%", TmpFD,
+                                      IndexTmpPath))
+    return EC_IOError;
+
+  // Open the temporary global index file for output.
+  llvm::raw_fd_ostream Out(TmpFD, true);
+  if (Out.has_error())
+    return EC_IOError;
+
+  // Write the index.
+  Out.write(OutputBuffer.data(), OutputBuffer.size());
+  Out.close();
+  if (Out.has_error())
+    return EC_IOError;
+
+  // Remove the old index file. It isn't relevant any more.
+  bool OldIndexExisted;
+  llvm::sys::fs::remove(IndexPath.str(), OldIndexExisted);
+
+  // Rename the newly-written index file to the proper name.
+  if (llvm::sys::fs::rename(IndexTmpPath.str(), IndexPath.str())) {
+    // Rename failed; just remove the 
+    llvm::sys::fs::remove(IndexTmpPath.str(), OldIndexExisted);
+    return EC_IOError;
+  }
+
+  // We're done.
+  return EC_None;
+}
+
+namespace {
+  class GlobalIndexIdentifierIterator : public IdentifierIterator {
+    /// \brief The current position within the identifier lookup table.
+    IdentifierIndexTable::key_iterator Current;
+
+    /// \brief The end position within the identifier lookup table.
+    IdentifierIndexTable::key_iterator End;
+
+  public:
+    explicit GlobalIndexIdentifierIterator(IdentifierIndexTable &Idx) {
+      Current = Idx.key_begin();
+      End = Idx.key_end();
+    }
+
+    virtual StringRef Next() {
+      if (Current == End)
+        return StringRef();
+
+      StringRef Result = *Current;
+      ++Current;
+      return Result;
+    }
+  };
+}
+
+IdentifierIterator *GlobalModuleIndex::createIdentifierIterator() const {
+  IdentifierIndexTable &Table =
+    *static_cast<IdentifierIndexTable *>(IdentifierIndex);
+  return new GlobalIndexIdentifierIterator(Table);
+}