Rework the (de-)serialization of macros, as stored in

MacroInfo*. Instead of simply dumping an offset into the current file,
give each macro definition a proper ID with all of the standard
modules-remapping facilities. Additionally, when a macro is modified
in a subsequent AST file (e.g., #undef'ing a macro loaded from another
module or from a precompiled header), provide a macro update record
rather than rewriting the entire macro definition. This gives us
greater consistency with the way we handle declarations, and ties
together macro definitions much more cleanly.

Note that we're still not actually deserializing macro history (we
never were), but it's far easy to do properly now.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@165560 91177308-0d34-0410-b5e6-96231b3b80d8

10 files changed, 266 insertions, 58 deletions

diff --git a/lib/Frontend/ChainedIncludesSource.cpp b/lib/Frontend/ChainedIncludesSource.cpp
index dbb06bd23c..5f7ff74bc6 100644
--- a/lib/Frontend/ChainedIncludesSource.cpp
+++ b/lib/Frontend/ChainedIncludesSource.cpp
@@ -108,6 +108,8 @@ ChainedIncludesSource *ChainedIncludesSource::create(CompilerInstance &CI) {
     OwningPtr<ASTConsumer> consumer;
     consumer.reset(new PCHGenerator(Clang->getPreprocessor(), "-", 0,
                                     /*isysroot=*/"", &OS));
+    Clang->getPreprocessor().setPPMutationListener(
+                                            consumer->GetPPMutationListener());
     Clang->getASTContext().setASTMutationListener(
                                             consumer->GetASTMutationListener());
     Clang->setASTConsumer(consumer.take());
diff --git a/lib/Frontend/CompilerInstance.cpp b/lib/Frontend/CompilerInstance.cpp
index bf46e549b5..24f38d428b 100644
--- a/lib/Frontend/CompilerInstance.cpp
+++ b/lib/Frontend/CompilerInstance.cpp
@@ -946,6 +946,8 @@ Module *CompilerInstance::loadModule(SourceLocation ImportLoc,
           getASTConsumer().GetASTDeserializationListener());
         getASTContext().setASTMutationListener(
           getASTConsumer().GetASTMutationListener());
+        getPreprocessor().setPPMutationListener(
+          getASTConsumer().GetPPMutationListener());
       }
       OwningPtr<ExternalASTSource> Source;
       Source.reset(ModuleManager);
diff --git a/lib/Frontend/FrontendAction.cpp b/lib/Frontend/FrontendAction.cpp
index a4321e720e..ca8511247a 100644
--- a/lib/Frontend/FrontendAction.cpp
+++ b/lib/Frontend/FrontendAction.cpp
@@ -247,7 +247,9 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
       goto failure;
 
     CI.getASTContext().setASTMutationListener(Consumer->GetASTMutationListener());
-
+    CI.getPreprocessor().setPPMutationListener(
+      Consumer->GetPPMutationListener());
+    
     if (!CI.getPreprocessorOpts().ChainedIncludes.empty()) {
       // Convert headers to PCH and chain them.
       OwningPtr<ExternalASTSource> source;
diff --git a/lib/Lex/PPDirectives.cpp b/lib/Lex/PPDirectives.cpp
index 23cbef63ed..9314517ed3 100644
--- a/lib/Lex/PPDirectives.cpp
+++ b/lib/Lex/PPDirectives.cpp
@@ -1944,8 +1944,20 @@ void Preprocessor::HandleUndefDirective(Token &UndefTok) {
   if (MI->isWarnIfUnused())
     WarnUnusedMacroLocs.erase(MI->getDefinitionLoc());
 
-  MI->setUndefLoc(MacroNameTok.getLocation());
-  clearMacroInfo(MacroNameTok.getIdentifierInfo());
+  UndefineMacro(MacroNameTok.getIdentifierInfo(), MI,
+                MacroNameTok.getLocation());
+}
+
+void Preprocessor::UndefineMacro(IdentifierInfo *II, MacroInfo *MI,
+                                 SourceLocation UndefLoc) {
+  MI->setUndefLoc(UndefLoc);
+  if (MI->isFromAST()) {
+    MI->setChangedAfterLoad();
+    if (Listener)
+      Listener->UndefinedMacro(MI);
+  }
+
+  clearMacroInfo(II);
 }
 
 
diff --git a/lib/Lex/Pragma.cpp b/lib/Lex/Pragma.cpp
index b5bc9583f6..1f9c811f55 100644
--- a/lib/Lex/Pragma.cpp
+++ b/lib/Lex/Pragma.cpp
@@ -737,7 +737,7 @@ void Preprocessor::HandlePragmaPopMacro(Token &PopMacroTok) {
     if (MacroInfo *CurrentMI = getMacroInfo(IdentInfo)) {
       if (CurrentMI->isWarnIfUnused())
         WarnUnusedMacroLocs.erase(CurrentMI->getDefinitionLoc());
-      CurrentMI->setUndefLoc(MessageLoc);
+      UndefineMacro(IdentInfo, CurrentMI, MessageLoc);
     }
 
     // Get the MacroInfo we want to reinstall.
diff --git a/lib/Lex/Preprocessor.cpp b/lib/Lex/Preprocessor.cpp
index a0fc265b6b..d9f206901d 100644
--- a/lib/Lex/Preprocessor.cpp
+++ b/lib/Lex/Preprocessor.cpp
@@ -49,6 +49,8 @@ using namespace clang;
 //===----------------------------------------------------------------------===//
 ExternalPreprocessorSource::~ExternalPreprocessorSource() { }
 
+PPMutationListener::~PPMutationListener() { }
+
 Preprocessor::Preprocessor(DiagnosticsEngine &diags, LangOptions &opts,
                            const TargetInfo *target, SourceManager &SM,
                            HeaderSearch &Headers, ModuleLoader &TheModuleLoader,
@@ -62,8 +64,8 @@ Preprocessor::Preprocessor(DiagnosticsEngine &diags, LangOptions &opts,
     IncrementalProcessing(IncrProcessing), CodeComplete(0), 
     CodeCompletionFile(0), CodeCompletionOffset(0), CodeCompletionReached(0),
     SkipMainFilePreamble(0, true), CurPPLexer(0), 
-    CurDirLookup(0), CurLexerKind(CLK_Lexer), Callbacks(0), MacroArgCache(0), 
-    Record(0), MIChainHead(0), MICache(0) 
+    CurDirLookup(0), CurLexerKind(CLK_Lexer), Callbacks(0), Listener(0),
+    MacroArgCache(0), Record(0), MIChainHead(0), MICache(0) 
 {
   OwnsHeaderSearch = OwnsHeaders;
   
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index b7266ebbba..cdb9646758 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -573,7 +573,7 @@ IdentifierInfo *ASTIdentifierLookupTrait::ReadData(const internal_key_type& k,
   // definition.
   if (hadMacroDefinition) {
     // FIXME: Check for conflicts?
-    uint32_t Offset = ReadUnalignedLE32(d);
+    uint32_t LocalID = ReadUnalignedLE32(d);
     unsigned LocalSubmoduleID = ReadUnalignedLE32(d);
     
     // Determine whether this macro definition should be visible now, or
@@ -594,7 +594,8 @@ IdentifierInfo *ASTIdentifierLookupTrait::ReadData(const internal_key_type& k,
       }
     }
 
-    Reader.setIdentifierIsMacro(II, F, Offset, Visible && hasMacroDefinition);
+    Reader.setIdentifierIsMacro(II, Reader.getGlobalMacroID(F, LocalID),
+                                Visible && hasMacroDefinition);
     DataLen -= 8;
   }
 
@@ -1314,10 +1315,19 @@ void ASTReader::ReadMacroRecord(ModuleFile &F, uint64_t Offset) {
         return;
       }
 
-      unsigned NextIndex = 1;
+      unsigned GlobalID = getGlobalMacroID(F, Record[1]);
+
+      // If this macro has already been loaded, don't do so again.
+      if (MacrosLoaded[GlobalID - NUM_PREDEF_MACRO_IDS])
+        return;
+
+      unsigned NextIndex = 2;
       SourceLocation Loc = ReadSourceLocation(F, Record, NextIndex);
       MacroInfo *MI = PP.AllocateMacroInfo(Loc);
 
+      // Record this macro.
+      MacrosLoaded[GlobalID - NUM_PREDEF_MACRO_IDS] = MI;
+
       SourceLocation UndefLoc = ReadSourceLocation(F, Record, NextIndex);
       if (UndefLoc.isValid())
         MI->setUndefLoc(UndefLoc);
@@ -1345,6 +1355,20 @@ void ASTReader::ReadMacroRecord(ModuleFile &F, uint64_t Offset) {
                             PP.getPreprocessorAllocator());
       }
 
+      if (DeserializationListener)
+        DeserializationListener->MacroRead(GlobalID, MI);
+
+      // If an update record marked this as undefined, do so now.
+      MacroUpdatesMap::iterator Update = MacroUpdates.find(GlobalID);
+      if (Update != MacroUpdates.end()) {
+        if (MI->getUndefLoc().isInvalid()) {
+          MI->setUndefLoc(Update->second.UndefLoc);
+          if (PPMutationListener *Listener = PP.getPPMutationListener())
+            Listener->UndefinedMacro(MI);
+        }
+        MacroUpdates.erase(Update);
+      }
+
       // Finally, install the macro.
       PP.setMacroInfo(II, MI, /*LoadedFromAST=*/true);
 
@@ -1455,17 +1479,18 @@ HeaderFileInfoTrait::ReadData(const internal_key_type, const unsigned char *d,
   return HFI;
 }
 
-void ASTReader::setIdentifierIsMacro(IdentifierInfo *II, ModuleFile &F,
-                                     uint64_t LocalOffset, bool Visible) {
+void ASTReader::setIdentifierIsMacro(IdentifierInfo *II, MacroID ID,
+                                     bool Visible) {
   if (Visible) {
     // Note that this identifier has a macro definition.
     II->setHasMacroDefinition(true);
   } else {
     II->setHadMacroDefinition(true);
   }
-  
-  // Adjust the offset to a global offset.
-  UnreadMacroRecordOffsets[II] = F.GlobalBitOffset + LocalOffset;
+
+  // FIXME: This could end up overwriting a previously recording macro
+  // definition here, which is not cool at all.
+  UnreadMacroIDs[II] = ID;
 }
 
 void ASTReader::ReadDefinedMacros() {
@@ -1522,23 +1547,21 @@ void ASTReader::ReadDefinedMacros() {
   }
   
   // Drain the unread macro-record offsets map.
-  while (!UnreadMacroRecordOffsets.empty())
-    LoadMacroDefinition(UnreadMacroRecordOffsets.begin());
+  while (!UnreadMacroIDs.empty())
+    LoadMacroDefinition(UnreadMacroIDs.begin());
 }
 
 void ASTReader::LoadMacroDefinition(
-                    llvm::DenseMap<IdentifierInfo *, uint64_t>::iterator Pos) {
-  assert(Pos != UnreadMacroRecordOffsets.end() && "Unknown macro definition");
-  uint64_t Offset = Pos->second;
-  UnreadMacroRecordOffsets.erase(Pos);
-  
-  RecordLocation Loc = getLocalBitOffset(Offset);
-  ReadMacroRecord(*Loc.F, Loc.Offset);
+                    llvm::DenseMap<IdentifierInfo *, MacroID>::iterator Pos) {
+  assert(Pos != UnreadMacroIDs.end() && "Unknown macro definition");
+  uint64_t GlobalID = Pos->second;
+  UnreadMacroIDs.erase(Pos);
+  getMacro(GlobalID);
 }
 
 void ASTReader::LoadMacroDefinition(IdentifierInfo *II) {
-  llvm::DenseMap<IdentifierInfo *, uint64_t>::iterator Pos
-    = UnreadMacroRecordOffsets.find(II);
+  llvm::DenseMap<IdentifierInfo *, MacroID>::iterator Pos
+    = UnreadMacroIDs.find(II);
   LoadMacroDefinition(Pos);
 }
 
@@ -1959,7 +1982,7 @@ ASTReader::ReadASTBlock(ModuleFile &F) {
       }
       break;
     }
-        
+
     case EXTERNAL_DEFINITIONS:
       for (unsigned I = 0, N = Record.size(); I != N; ++I)
         ExternalDefinitions.push_back(getGlobalDeclID(F, Record[I]));
@@ -2109,7 +2132,9 @@ ASTReader::ReadASTBlock(ModuleFile &F) {
       ContinuousRangeMap<uint32_t, int, 2>::Builder SLocRemap(F.SLocRemap);
       ContinuousRangeMap<uint32_t, int, 2>::Builder 
         IdentifierRemap(F.IdentifierRemap);
-      ContinuousRangeMap<uint32_t, int, 2>::Builder 
+      ContinuousRangeMap<uint32_t, int, 2>::Builder
+        MacroRemap(F.MacroRemap);
+      ContinuousRangeMap<uint32_t, int, 2>::Builder
         PreprocessedEntityRemap(F.PreprocessedEntityRemap);
       ContinuousRangeMap<uint32_t, int, 2>::Builder 
         SubmoduleRemap(F.SubmoduleRemap);
@@ -2130,6 +2155,7 @@ ASTReader::ReadASTBlock(ModuleFile &F) {
 
         uint32_t SLocOffset = io::ReadUnalignedLE32(Data);
         uint32_t IdentifierIDOffset = io::ReadUnalignedLE32(Data);
+        uint32_t MacroIDOffset = io::ReadUnalignedLE32(Data);
         uint32_t PreprocessedEntityIDOffset = io::ReadUnalignedLE32(Data);
         uint32_t SubmoduleIDOffset = io::ReadUnalignedLE32(Data);
         uint32_t SelectorIDOffset = io::ReadUnalignedLE32(Data);
@@ -2142,6 +2168,8 @@ ASTReader::ReadASTBlock(ModuleFile &F) {
         IdentifierRemap.insert(
           std::make_pair(IdentifierIDOffset, 
                          OM->BaseIdentifierID - IdentifierIDOffset));
+        MacroRemap.insert(std::make_pair(MacroIDOffset,
+                                         OM->BaseMacroID - MacroIDOffset));
         PreprocessedEntityRemap.insert(
           std::make_pair(PreprocessedEntityIDOffset, 
             OM->BasePreprocessedEntityID - PreprocessedEntityIDOffset));
@@ -2458,6 +2486,41 @@ ASTReader::ReadASTBlock(ModuleFile &F) {
       }
       break;
     }
+
+    case MACRO_OFFSET: {
+      if (F.LocalNumMacros != 0) {
+        Error("duplicate MACRO_OFFSET record in AST file");
+        return Failure;
+      }
+      F.MacroOffsets = (const uint32_t *)BlobStart;
+      F.LocalNumMacros = Record[0];
+      unsigned LocalBaseMacroID = Record[1];
+      F.BaseMacroID = getTotalNumMacros();
+
+      if (F.LocalNumMacros > 0) {
+        // Introduce the global -> local mapping for macros within this module.
+        GlobalMacroMap.insert(std::make_pair(getTotalNumMacros() + 1, &F));
+
+        // Introduce the local -> global mapping for macros within this module.
+        F.MacroRemap.insertOrReplace(
+          std::make_pair(LocalBaseMacroID,
+                         F.BaseMacroID - LocalBaseMacroID));
+
+        MacrosLoaded.resize(MacrosLoaded.size() + F.LocalNumMacros);
+      }
+      break;
+    }
+
+    case MACRO_UPDATES: {
+      for (unsigned I = 0, N = Record.size(); I != N; /* in loop */) {
+        MacroID ID = getGlobalMacroID(F, Record[I++]);
+        if (I == N)
+          break;
+
+        MacroUpdates[ID].UndefLoc = ReadSourceLocation(F, Record, I);
+      }
+      break;
+    }
     }
   }
   Error("premature end of bitstream in AST file");
@@ -5195,6 +5258,10 @@ void ASTReader::PrintStats() {
     = IdentifiersLoaded.size() - std::count(IdentifiersLoaded.begin(),
                                             IdentifiersLoaded.end(),
                                             (IdentifierInfo *)0);
+  unsigned NumMacrosLoaded
+    = MacrosLoaded.size() - std::count(MacrosLoaded.begin(),
+                                       MacrosLoaded.end(),
+                                       (MacroInfo *)0);
   unsigned NumSelectorsLoaded
     = SelectorsLoaded.size() - std::count(SelectorsLoaded.begin(),
                                           SelectorsLoaded.end(),
@@ -5218,6 +5285,10 @@ void ASTReader::PrintStats() {
     std::fprintf(stderr, "  %u/%u identifiers read (%f%%)\n",
                  NumIdentifiersLoaded, (unsigned)IdentifiersLoaded.size(),
                  ((float)NumIdentifiersLoaded/IdentifiersLoaded.size() * 100));
+  if (!MacrosLoaded.empty())
+    std::fprintf(stderr, "  %u/%u macros read (%f%%)\n",
+                 NumMacrosLoaded, (unsigned)MacrosLoaded.size(),
+                 ((float)NumMacrosLoaded/MacrosLoaded.size() * 100));
   if (!SelectorsLoaded.empty())
     std::fprintf(stderr, "  %u/%u selectors read (%f%%)\n",
                  NumSelectorsLoaded, (unsigned)SelectorsLoaded.size(),
@@ -5276,6 +5347,7 @@ void ASTReader::dump() {
   dumpModuleIDMap("Global type map", GlobalTypeMap);
   dumpModuleIDMap("Global declaration map", GlobalDeclMap);
   dumpModuleIDMap("Global identifier map", GlobalIdentifierMap);
+  dumpModuleIDMap("Global macro map", GlobalMacroMap);
   dumpModuleIDMap("Global submodule map", GlobalSubmoduleMap);
   dumpModuleIDMap("Global selector map", GlobalSelectorMap);
   dumpModuleIDMap("Global preprocessed entity map", 
@@ -5746,6 +5818,39 @@ IdentifierID ASTReader::getGlobalIdentifierID(ModuleFile &M, unsigned LocalID) {
   return LocalID + I->second;
 }
 
+MacroInfo *ASTReader::getMacro(MacroID ID) {
+  if (ID == 0)
+    return 0;
+
+  if (MacrosLoaded.empty()) {
+    Error("no macro table in AST file");
+    return 0;
+  }
+
+  ID -= NUM_PREDEF_MACRO_IDS;
+  if (!MacrosLoaded[ID]) {
+    GlobalMacroMapType::iterator I
+      = GlobalMacroMap.find(ID + NUM_PREDEF_MACRO_IDS);
+    assert(I != GlobalMacroMap.end() && "Corrupted global macro map");
+    ModuleFile *M = I->second;
+    unsigned Index = ID - M->BaseMacroID;
+    ReadMacroRecord(*M, M->MacroOffsets[Index]);
+  }
+
+  return MacrosLoaded[ID];
+}
+
+MacroID ASTReader::getGlobalMacroID(ModuleFile &M, unsigned LocalID) {
+  if (LocalID < NUM_PREDEF_MACRO_IDS)
+    return LocalID;
+
+  ContinuousRangeMap<uint32_t, int, 2>::iterator I
+    = M.MacroRemap.find(LocalID - NUM_PREDEF_MACRO_IDS);
+  assert(I != M.MacroRemap.end() && "Invalid index into macro index remap");
+
+  return LocalID + I->second;
+}
+
 bool ASTReader::ReadSLocEntry(int ID) {
   return ReadSLocEntryRecord(ID) != Success;
 }
@@ -5758,7 +5863,7 @@ ASTReader::getGlobalSubmoduleID(ModuleFile &M, unsigned LocalID) {
   ContinuousRangeMap<uint32_t, int, 2>::iterator I
     = M.SubmoduleRemap.find(LocalID - NUM_PREDEF_SUBMODULE_IDS);
   assert(I != M.SubmoduleRemap.end() 
-         && "Invalid index into identifier index remap");
+         && "Invalid index into submodule index remap");
   
   return LocalID + I->second;
 }
@@ -5823,7 +5928,7 @@ ASTReader::getGlobalSelectorID(ModuleFile &M, unsigned LocalID) const {
   ContinuousRangeMap<uint32_t, int, 2>::iterator I
     = M.SelectorRemap.find(LocalID - NUM_PREDEF_SELECTOR_IDS);
   assert(I != M.SelectorRemap.end() 
-         && "Invalid index into identifier index remap");
+         && "Invalid index into selector index remap");
   
   return LocalID + I->second;
 }
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index 19a236fde2..76eb1a1a8a 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -820,6 +820,8 @@ void ASTWriter::WriteBlockInfoBlock() {
   RECORD(MERGED_DECLARATIONS);
   RECORD(LOCAL_REDECLARATIONS);
   RECORD(OBJC_CATEGORIES);
+  RECORD(MACRO_OFFSET);
+  RECORD(MACRO_UPDATES);
 
   // SourceManager Block.
   BLOCK(SOURCE_MANAGER_BLOCK);
@@ -1702,37 +1704,46 @@ void ASTWriter::WritePreprocessor(const Preprocessor &PP, bool IsModule) {
                                             PP.getMacroInfoHistory(Name)));
   }
 
+  /// \brief Offsets of each of the macros into the bitstream, indexed by
+  /// the local macro ID
+  ///
+  /// For each identifier that is associated with a macro, this map
+  /// provides the offset into the bitstream where that macro is
+  /// defined.
+  std::vector<uint32_t> MacroOffsets;
+
   for (unsigned I = 0, N = MacrosToEmit.size(); I != N; ++I) {
     const IdentifierInfo *Name = MacrosToEmit[I].first;
-    MacroInfo *MI = MacrosToEmit[I].second;
 
-    // History of macro definitions for this identifier in chronological order.
-    SmallVector<MacroInfo*, 8> MacroHistory;
-    while (MI) {
-      MacroHistory.push_back(MI);
-      MI = MI->getPreviousDefinition();
-    }
+    for (MacroInfo *MI = MacrosToEmit[I].second; MI;
+         MI = MI->getPreviousDefinition()) {
+      MacroID ID = getMacroRef(MI);
+      if (!ID)
+        continue;
+
+      // Skip macros from a AST file if we're chaining.
+      if (Chain && MI->isFromAST() && !MI->hasChangedAfterLoad())
+        continue;
 
-    while (!MacroHistory.empty()) {
-      MI = MacroHistory.pop_back_val();
-
-      // Don't emit builtin macros like __LINE__ to the AST file unless they
-      // have been redefined by the header (in which case they are not
-      // isBuiltinMacro).
-      // Also skip macros from a AST file if we're chaining.
-
-      // FIXME: There is a (probably minor) optimization we could do here, if
-      // the macro comes from the original PCH but the identifier comes from a
-      // chained PCH, by storing the offset into the original PCH rather than
-      // writing the macro definition a second time.
-      if (MI->isBuiltinMacro() ||
-          (Chain &&
-           Name->isFromAST() && !Name->hasChangedSinceDeserialization() &&
-           MI->isFromAST() && !MI->hasChangedAfterLoad()))
+      if (ID < FirstMacroID) {
+        // This will have been dealt with via an update record.
+        assert(MacroUpdates.count(MI) > 0 && "Missing macro update");
         continue;
+      }
+
+      // Record the local offset of this macro.
+      unsigned Index = ID - FirstMacroID;
+      if (Index == MacroOffsets.size())
+        MacroOffsets.push_back(Stream.GetCurrentBitNo());
+      else {
+        if (Index > MacroOffsets.size())
+          MacroOffsets.resize(Index + 1);
+
+        MacroOffsets[Index] = Stream.GetCurrentBitNo();
+      }
 
       AddIdentifierRef(Name, Record);
-      MacroOffsets[Name] = Stream.GetCurrentBitNo();
+      addMacroRef(MI, Record);
       AddSourceLocation(MI->getDefinitionLoc(), Record);
       AddSourceLocation(MI->getUndefLoc(), Record);
       Record.push_back(MI->isUsed());
@@ -1785,6 +1796,22 @@ void ASTWriter::WritePreprocessor(const Preprocessor &PP, bool IsModule) {
     }
   }
   Stream.ExitBlock();
+
+  // Write the offsets table for macro IDs.
+  using namespace llvm;
+  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
+  Abbrev->Add(BitCodeAbbrevOp(MACRO_OFFSET));
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // # of macros
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // first ID
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
+
+  unsigned MacroOffsetAbbrev = Stream.EmitAbbrev(Abbrev);
+  Record.clear();
+  Record.push_back(MACRO_OFFSET);
+  Record.push_back(MacroOffsets.size());
+  Record.push_back(FirstMacroID - NUM_PREDEF_MACRO_IDS);
+  Stream.EmitRecordWithBlob(MacroOffsetAbbrev, Record,
+                            data(MacroOffsets));
 }
 
 void ASTWriter::WritePreprocessorDetail(PreprocessingRecord &PPRec) {
@@ -2608,7 +2635,7 @@ public:
     clang::io::Emit16(Out, Bits);
 
     if (HadMacroDefinition) {
-      clang::io::Emit32(Out, Writer.getMacroOffset(II));
+      clang::io::Emit32(Out, Writer.getMacroRef(Macro));
       clang::io::Emit32(Out,
         Writer.inferSubmoduleIDFromLocation(Macro->getDefinitionLoc()));
     }
@@ -3182,7 +3209,8 @@ ASTWriter::ASTWriter(llvm::BitstreamWriter &Stream)
     ASTHasCompilerErrors(false),
     FirstDeclID(NUM_PREDEF_DECL_IDS), NextDeclID(FirstDeclID),
     FirstTypeID(NUM_PREDEF_TYPE_IDS), NextTypeID(FirstTypeID),
-    FirstIdentID(NUM_PREDEF_IDENT_IDS), NextIdentID(FirstIdentID), 
+    FirstIdentID(NUM_PREDEF_IDENT_IDS), NextIdentID(FirstIdentID),
+    FirstMacroID(NUM_PREDEF_MACRO_IDS), NextMacroID(FirstMacroID),
     FirstSubmoduleID(NUM_PREDEF_SUBMODULE_IDS), 
     NextSubmoduleID(FirstSubmoduleID),
     FirstSelectorID(NUM_PREDEF_SELECTOR_IDS), NextSelectorID(FirstSelectorID),
@@ -3517,6 +3545,7 @@ void ASTWriter::WriteASTCore(Sema &SemaRef, MemorizeStatCalls *StatCalls,
         Out.write(FileName.data(), FileName.size());
         io::Emit32(Out, (*M)->SLocEntryBaseOffset);
         io::Emit32(Out, (*M)->BaseIdentifierID);
+        io::Emit32(Out, (*M)->BaseMacroID);
         io::Emit32(Out, (*M)->BasePreprocessedEntityID);
         io::Emit32(Out, (*M)->BaseSubmoduleID);
         io::Emit32(Out, (*M)->BaseSelectorID);
@@ -3630,7 +3659,8 @@ void ASTWriter::WriteASTCore(Sema &SemaRef, MemorizeStatCalls *StatCalls,
       Stream.EmitRecord(IMPORTED_MODULES, ImportedModules);
     }
   }
-  
+
+  WriteMacroUpdates();
   WriteDeclUpdatesBlocks();
   WriteDeclReplacementsBlock();
   WriteMergedDecls();
@@ -3647,6 +3677,20 @@ void ASTWriter::WriteASTCore(Sema &SemaRef, MemorizeStatCalls *StatCalls,
   Stream.ExitBlock();
 }
 
+void ASTWriter::WriteMacroUpdates() {
+  if (MacroUpdates.empty())
+    return;
+
+  RecordData Record;
+  for (MacroUpdatesMap::iterator I = MacroUpdates.begin(),
+                                 E = MacroUpdates.end();
+       I != E; ++I) {
+    addMacroRef(I->first, Record);
+    AddSourceLocation(I->second.UndefLoc, Record);
+  }
+  Stream.EmitRecord(MACRO_UPDATES, Record);
+}
+
 /// \brief Go through the declaration update blocks and resolve declaration
 /// pointers into declaration IDs.
 void ASTWriter::ResolveDeclUpdatesBlocks() {
@@ -3742,6 +3786,10 @@ void ASTWriter::AddIdentifierRef(const IdentifierInfo *II, RecordDataImpl &Recor
   Record.push_back(getIdentifierRef(II));
 }
 
+void ASTWriter::addMacroRef(MacroInfo *MI, RecordDataImpl &Record) {
+  Record.push_back(getMacroRef(MI));
+}
+
 IdentID ASTWriter::getIdentifierRef(const IdentifierInfo *II) {
   if (II == 0)
     return 0;
@@ -3752,6 +3800,19 @@ IdentID ASTWriter::getIdentifierRef(const IdentifierInfo *II) {
   return ID;
 }
 
+MacroID ASTWriter::getMacroRef(MacroInfo *MI) {
+  // Don't emit builtin macros like __LINE__ to the AST file unless they
+  // have been redefined by the header (in which case they are not
+  // isBuiltinMacro).
+  if (MI == 0 || MI->isBuiltinMacro())
+    return 0;
+
+  MacroID &ID = MacroIDs[MI];
+  if (ID == 0)
+    ID = NextMacroID++;
+  return ID;
+}
+
 void ASTWriter::AddSelectorRef(const Selector SelRef, RecordDataImpl &Record) {
   Record.push_back(getSelectorRef(SelRef));
 }
@@ -4464,6 +4525,7 @@ void ASTWriter::ReaderInitialized(ASTReader *Reader) {
   assert(FirstDeclID == NextDeclID &&
          FirstTypeID == NextTypeID &&
          FirstIdentID == NextIdentID &&
+         FirstMacroID == NextMacroID &&
          FirstSubmoduleID == NextSubmoduleID &&
          FirstSelectorID == NextSelectorID &&
          "Setting chain after writing has started.");
@@ -4473,11 +4535,13 @@ void ASTWriter::ReaderInitialized(ASTReader *Reader) {
   FirstDeclID = NUM_PREDEF_DECL_IDS + Chain->getTotalNumDecls();
   FirstTypeID = NUM_PREDEF_TYPE_IDS + Chain->getTotalNumTypes();
   FirstIdentID = NUM_PREDEF_IDENT_IDS + Chain->getTotalNumIdentifiers();
+  FirstMacroID = NUM_PREDEF_MACRO_IDS + Chain->getTotalNumMacros();
   FirstSubmoduleID = NUM_PREDEF_SUBMODULE_IDS + Chain->getTotalNumSubmodules();
   FirstSelectorID = NUM_PREDEF_SELECTOR_IDS + Chain->getTotalNumSelectors();
   NextDeclID = FirstDeclID;
   NextTypeID = FirstTypeID;
   NextIdentID = FirstIdentID;
+  NextMacroID = FirstMacroID;
   NextSelectorID = FirstSelectorID;
   NextSubmoduleID = FirstSubmoduleID;
 }
@@ -4488,6 +4552,10 @@ void ASTWriter::IdentifierRead(IdentID ID, IdentifierInfo *II) {
     DeserializedMacroNames.push_back(II);
 }
 
+void ASTWriter::MacroRead(serialization::MacroID ID, MacroInfo *MI) {
+  MacroIDs[MI] = ID;
+}
+
 void ASTWriter::TypeRead(TypeIdx Idx, QualType T) {
   // Always take the highest-numbered type index. This copes with an interesting
   // case for chained AST writing where we schedule writing the type and then,
@@ -4518,6 +4586,10 @@ void ASTWriter::ModuleRead(serialization::SubmoduleID ID, Module *Mod) {
   SubmoduleIDs[Mod] = ID;
 }
 
+void ASTWriter::UndefinedMacro(MacroInfo *MI) {
+  MacroUpdates[MI].UndefLoc = MI->getUndefLoc();
+}
+
 void ASTWriter::CompletedTagDefinition(const TagDecl *D) {
   assert(D->isCompleteDefinition());
   assert(!WritingAST && "Already writing the AST!");
@@ -4531,6 +4603,7 @@ void ASTWriter::CompletedTagDefinition(const TagDecl *D) {
     }
   }
 }
+
 void ASTWriter::AddedVisibleDecl(const DeclContext *DC, const Decl *D) {
   assert(!WritingAST && "Already writing the AST!");
 
diff --git a/lib/Serialization/GeneratePCH.cpp b/lib/Serialization/GeneratePCH.cpp
index 02aed103f1..c2b353a964 100644
--- a/lib/Serialization/GeneratePCH.cpp
+++ b/lib/Serialization/GeneratePCH.cpp
@@ -60,6 +60,10 @@ void PCHGenerator::HandleTranslationUnit(ASTContext &Ctx) {
   Buffer.clear();
 }
 
+PPMutationListener *PCHGenerator::GetPPMutationListener() {
+  return &Writer;
+}
+
 ASTMutationListener *PCHGenerator::GetASTMutationListener() {
   return &Writer;
 }
diff --git a/lib/Serialization/Module.cpp b/lib/Serialization/Module.cpp
index a5f709153c..b6204f9478 100644
--- a/lib/Serialization/Module.cpp
+++ b/lib/Serialization/Module.cpp
@@ -25,9 +25,11 @@ ModuleFile::ModuleFile(ModuleKind Kind, unsigned Generation)
     Generation(Generation), SizeInBits(0),
     LocalNumSLocEntries(0), SLocEntryBaseID(0),
     SLocEntryBaseOffset(0), SLocEntryOffsets(0),
-    SLocFileOffsets(0), LocalNumIdentifiers(0), 
+    SLocFileOffsets(0), LocalNumIdentifiers(0),
     IdentifierOffsets(0), BaseIdentifierID(0), IdentifierTableData(0),
-    IdentifierLookupTable(0), BasePreprocessedEntityID(0),
+    IdentifierLookupTable(0),
+    LocalNumMacros(0), MacroOffsets(0),
+    BasePreprocessedEntityID(0),
     PreprocessedEntityOffsets(0), NumPreprocessedEntities(0),
     LocalNumHeaderFileInfos(0), 
     HeaderFileInfoTableData(0), HeaderFileInfoTable(0),
@@ -91,6 +93,10 @@ void ModuleFile::dump() {
                << "  Number of identifiers: " << LocalNumIdentifiers << '\n';
   dumpLocalRemap("Identifier ID local -> global map", IdentifierRemap);
 
+  llvm::errs() << "  Base macro ID: " << BaseMacroID << '\n'
+               << "  Number of macros: " << LocalNumMacros << '\n';
+  dumpLocalRemap("Macro ID local -> global map", MacroRemap);
+
   llvm::errs() << "  Base submodule ID: " << BaseSubmoduleID << '\n'
                << "  Number of submodules: " << LocalNumSubmodules << '\n';
   dumpLocalRemap("Submodule ID local -> global map", SubmoduleRemap);