In the serialized AST format, make the translation unit a "predefined"

declaration that never actually gets serialized. Instead, serialize
the various kinds of update records (lexical decls, visible decls, the
addition of an anonymous namespace) for the translation unit, even if
we're not chaining. This way, we won't have to deal with multiple
loaded translation unit declarations.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@137395 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 106 insertions, 56 deletions

diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 1bda1ed42a..43435b6754 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -2091,7 +2091,8 @@ ASTReader::ReadASTBlock(Module &F) {
       if (F.LocalNumDecls > 0) {
         // Introduce the global -> local mapping for declarations within this 
         // module.
-        GlobalDeclMap.insert(std::make_pair(getTotalNumDecls() + 1, &F));
+        GlobalDeclMap.insert(
+          std::make_pair(getTotalNumDecls() + NUM_PREDEF_DECL_IDS, &F));
         
         // Introduce the local -> global mapping for declarations within this
         // module.
@@ -2110,8 +2111,12 @@ ASTReader::ReadASTBlock(Module &F) {
         reinterpret_cast<const KindDeclIDPair *>(BlobStart),
         static_cast<unsigned int>(BlobLen / sizeof(KindDeclIDPair))
       };
-      DeclContextOffsets[Context ? Context->getTranslationUnitDecl() : 0]
-        .push_back(Info);
+
+      DeclContext *TU = Context ? Context->getTranslationUnitDecl() : 0;
+      DeclContextOffsets[TU].push_back(Info);
+      if (TU)
+        TU->setHasExternalLexicalStorage(true);
+
       break;
     }
 
@@ -2123,11 +2128,14 @@ ASTReader::ReadASTBlock(Module &F) {
                         (const unsigned char *)BlobStart,
                         ASTDeclContextNameLookupTrait(*this, F));
       // FIXME: Complete hack to check for the TU
-      if (ID == (*(ModuleMgr.end() - 1))->BaseDeclID + 1 && Context) { // Is it the TU?
+      if (ID == PREDEF_DECL_TRANSLATION_UNIT_ID && Context) { // Is it the TU?
         DeclContextInfo Info = {
           &F, Table, /* No lexical information */ 0, 0
         };
-        DeclContextOffsets[Context->getTranslationUnitDecl()].push_back(Info);
+
+        DeclContext *TU = Context->getTranslationUnitDecl();
+        DeclContextOffsets[TU].push_back(Info);
+        TU->setHasExternalVisibleStorage(true);
       } else
         PendingVisibleUpdates[ID].push_back(std::make_pair(Table, &F));
       break;
@@ -2948,17 +2956,27 @@ void ASTReader::InitializeContext(ASTContext &Ctx) {
   
   // If we have an update block for the TU waiting, we have to add it before
   // deserializing the decl.
+  TranslationUnitDecl *TU = Ctx.getTranslationUnitDecl();
   DeclContextOffsetsMap::iterator DCU = DeclContextOffsets.find(0);
   if (DCU != DeclContextOffsets.end()) {
     // Insertion could invalidate map, so grab vector.
     DeclContextInfos T;
     T.swap(DCU->second);
     DeclContextOffsets.erase(DCU);
-    DeclContextOffsets[Ctx.getTranslationUnitDecl()].swap(T);
+    DeclContextOffsets[TU].swap(T);
   }
+  
+  // If there's a listener, notify them that we "read" the translation unit.
+  if (DeserializationListener)
+    DeserializationListener->DeclRead(PREDEF_DECL_TRANSLATION_UNIT_ID, TU);
 
-  // Load the translation unit declaration
-  GetTranslationUnitDecl();
+  // Make sure we load the declaration update records for the translation unit,
+  // if there are any.
+  loadDeclUpdateRecords(PREDEF_DECL_TRANSLATION_UNIT_ID, TU);
+  
+  // Note that the translation unit has external lexical and visible storage.
+  TU->setHasExternalLexicalStorage(true);
+  TU->setHasExternalVisibleStorage(true);
 
   // FIXME: Find a better way to deal with collisions between these
   // built-in types. Right now, we just ignore the problem.
@@ -4186,21 +4204,6 @@ CXXBaseSpecifier *ASTReader::GetExternalCXXBaseSpecifiers(uint64_t Offset) {
   return Bases;
 }
 
-TranslationUnitDecl *ASTReader::GetTranslationUnitDecl() {
-  // FIXME: This routine might not even make sense when we're loading multiple
-  // unrelated AST files, since we'll have to merge the translation units
-  // somehow.
-  unsigned TranslationUnitID = (*(ModuleMgr.end() - 1))->BaseDeclID + 1;
-  if (!DeclsLoaded[TranslationUnitID - 1]) {
-    ReadDeclRecord(TranslationUnitID);
-    if (DeserializationListener)
-      DeserializationListener->DeclRead(TranslationUnitID, 
-                                        DeclsLoaded[TranslationUnitID - 1]);
-  }
-
-  return cast<TranslationUnitDecl>(DeclsLoaded[TranslationUnitID - 1]);
-}
-
 serialization::DeclID 
 ASTReader::getGlobalDeclID(Module &F, unsigned LocalID) const {
   if (LocalID < NUM_PREDEF_DECL_IDS)
@@ -4216,20 +4219,25 @@ ASTReader::getGlobalDeclID(Module &F, unsigned LocalID) const {
 Decl *ASTReader::GetDecl(DeclID ID) {
   if (ID < NUM_PREDEF_DECL_IDS) {    
     switch ((PredefinedDeclIDs)ID) {
-    case serialization::PREDEF_DECL_NULL_ID:
+    case PREDEF_DECL_NULL_ID:
       return 0;
+        
+    case PREDEF_DECL_TRANSLATION_UNIT_ID:
+      assert(Context && "No context available?");
+      return Context->getTranslationUnitDecl();
     }
     
     return 0;
   }
   
-  if (ID > DeclsLoaded.size()) {
+  unsigned Index = ID - NUM_PREDEF_DECL_IDS;
+
+  if (Index > DeclsLoaded.size()) {
     Error("declaration ID out-of-range for AST file");
     return 0;
   }
-
-  unsigned Index = ID - NUM_PREDEF_DECL_IDS;
-  if (!DeclsLoaded[Index]) {
+  
+if (!DeclsLoaded[Index]) {
     ReadDeclRecord(ID);
     if (DeserializationListener)
       DeserializationListener->DeclRead(ID, DeclsLoaded[Index]);
@@ -5666,7 +5674,7 @@ void Module::dump() {
   
   llvm::errs() << "  Base preprocessed entity ID: " << BasePreprocessedEntityID
                << '\n'  
-               << "Number of preprocessed entities: " 
+               << "  Number of preprocessed entities: " 
                << NumPreallocatedPreprocessingEntities << '\n';
   dumpLocalRemap("Preprocessed entity ID local -> global map", 
                  PreprocessedEntityRemap);
diff --git a/lib/Serialization/ASTReaderDecl.cpp b/lib/Serialization/ASTReaderDecl.cpp
index 707ee8a8bb..02bd21fef0 100644
--- a/lib/Serialization/ASTReaderDecl.cpp
+++ b/lib/Serialization/ASTReaderDecl.cpp
@@ -243,8 +243,7 @@ void ASTDeclReader::VisitDecl(Decl *D) {
 }
 
 void ASTDeclReader::VisitTranslationUnitDecl(TranslationUnitDecl *TU) {
-  VisitDecl(TU);
-  TU->setAnonymousNamespace(ReadDeclAs<NamespaceDecl>(Record, Idx));
+  llvm_unreachable("Translation units are not serialized");
 }
 
 void ASTDeclReader::VisitNamedDecl(NamedDecl *ND) {
@@ -1444,7 +1443,7 @@ void ASTReader::loadAndAttachPreviousDecl(Decl *D, serialization::DeclID ID) {
 
 /// \brief Read the declaration at the given offset from the AST file.
 Decl *ASTReader::ReadDeclRecord(DeclID ID) {
-  unsigned Index = ID - 1;
+  unsigned Index = ID - NUM_PREDEF_DECL_IDS;
   RecordLocation Loc = DeclCursorForID(ID);
   llvm::BitstreamCursor &DeclsCursor = Loc.F->DeclsCursor;
   // Keep track of where we are in the stream, then jump back there
@@ -1468,11 +1467,6 @@ Decl *ASTReader::ReadDeclRecord(DeclID ID) {
   case DECL_CONTEXT_VISIBLE:
     assert(false && "Record cannot be de-serialized with ReadDeclRecord");
     break;
-  case DECL_TRANSLATION_UNIT:
-    assert(Index == Loc.F->BaseDeclID && 
-           "Translation unit must be at first index in file");
-    D = Context->getTranslationUnitDecl();
-    break;
   case DECL_TYPEDEF:
     D = TypedefDecl::Create(*Context, 0, SourceLocation(), SourceLocation(),
                             0, 0);
@@ -1727,6 +1721,20 @@ Decl *ASTReader::ReadDeclRecord(DeclID ID) {
   }
   assert(Idx == Record.size());
 
+  // Load any relevant update records.
+  loadDeclUpdateRecords(ID, D);
+  
+  // If we have deserialized a declaration that has a definition the
+  // AST consumer might need to know about, queue it.
+  // We don't pass it to the consumer immediately because we may be in recursive
+  // loading, and some declarations may still be initializing.
+  if (isConsumerInterestedIn(D))
+    InterestingDecls.push_back(D);
+
+  return D;
+}
+
+void ASTReader::loadDeclUpdateRecords(serialization::DeclID ID, Decl *D) {
   // The declaration may have been modified by files later in the chain.
   // If this is the case, read the record containing the updates from each file
   // and pass it to ASTDeclReader to make the modifications.
@@ -1734,7 +1742,7 @@ Decl *ASTReader::ReadDeclRecord(DeclID ID) {
   if (UpdI != DeclUpdateOffsets.end()) {
     FileOffsetsTy &UpdateOffsets = UpdI->second;
     for (FileOffsetsTy::iterator
-           I = UpdateOffsets.begin(), E = UpdateOffsets.end(); I != E; ++I) {
+         I = UpdateOffsets.begin(), E = UpdateOffsets.end(); I != E; ++I) {
       Module *F = I->first;
       uint64_t Offset = I->second;
       llvm::BitstreamCursor &Cursor = F->DeclsCursor;
@@ -1745,20 +1753,15 @@ Decl *ASTReader::ReadDeclRecord(DeclID ID) {
       unsigned RecCode = Cursor.ReadRecord(Code, Record);
       (void)RecCode;
       assert(RecCode == DECL_UPDATES && "Expected DECL_UPDATES record!");
+      
+      unsigned Idx = 0;
+      ASTDeclReader Reader(*this, *F, Cursor, ID, Record, Idx);
       Reader.UpdateDecl(D, *F, Record);
     }
   }
-
-  // If we have deserialized a declaration that has a definition the
-  // AST consumer might need to know about, queue it.
-  // We don't pass it to the consumer immediately because we may be in recursive
-  // loading, and some declarations may still be initializing.
-  if (isConsumerInterestedIn(D))
-    InterestingDecls.push_back(D);
-
-  return D;
 }
 
+
 void ASTDeclReader::UpdateDecl(Decl *D, Module &Module,
                                const RecordData &Record) {
   unsigned Idx = 0;
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index fe747a5150..5b93de4d30 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -841,7 +841,6 @@ void ASTWriter::WriteBlockInfoBlock() {
   RECORD(TYPE_PACK_EXPANSION);
   RECORD(TYPE_ATTRIBUTED);
   RECORD(TYPE_SUBST_TEMPLATE_TYPE_PARM_PACK);
-  RECORD(DECL_TRANSLATION_UNIT);
   RECORD(DECL_TYPEDEF);
   RECORD(DECL_ENUM);
   RECORD(DECL_RECORD);
@@ -2810,10 +2809,8 @@ void ASTWriter::WriteASTCore(Sema &SemaRef, MemorizeStatCalls *StatCalls,
   ASTContext &Context = SemaRef.Context;
   Preprocessor &PP = SemaRef.PP;
 
-  // The translation unit is the first declaration we'll emit.
-  DeclIDs[Context.getTranslationUnitDecl()] = 1;
-  ++NextDeclID;
-  DeclTypesToEmit.push(Context.getTranslationUnitDecl());
+  // Set up predefined declaration IDs.
+  DeclIDs[Context.getTranslationUnitDecl()] = PREDEF_DECL_TRANSLATION_UNIT_ID;
 
   // Make sure that we emit IdentifierInfos (and any attached
   // declarations) for builtins.
@@ -2942,6 +2939,45 @@ void ASTWriter::WriteASTCore(Sema &SemaRef, MemorizeStatCalls *StatCalls,
   AddTypeRef(Context.ObjCSelRedefinitionType, SpecialTypes);
   SpecialTypes.push_back(Context.isInt128Installed());
 
+  // We don't start with the translation unit, but with its decls that
+  // don't come from the chained PCH.
+  const TranslationUnitDecl *TU = Context.getTranslationUnitDecl();
+  SmallVector<KindDeclIDPair, 64> NewGlobalDecls;
+  for (DeclContext::decl_iterator I = TU->noload_decls_begin(),
+       E = TU->noload_decls_end();
+       I != E; ++I) {
+    if ((*I)->getPCHLevel() == 0)
+      NewGlobalDecls.push_back(std::make_pair((*I)->getKind(), GetDeclRef(*I)));
+    else if ((*I)->isChangedSinceDeserialization())
+      (void)GetDeclRef(*I); // Make sure it's written, but don't record it.
+  }
+  // We also need to write a lexical updates block for the TU.
+  llvm::BitCodeAbbrev *Abv = new llvm::BitCodeAbbrev();
+  Abv->Add(llvm::BitCodeAbbrevOp(TU_UPDATE_LEXICAL));
+  Abv->Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::Blob));
+  unsigned TuUpdateLexicalAbbrev = Stream.EmitAbbrev(Abv);
+  Record.clear();
+  Record.push_back(TU_UPDATE_LEXICAL);
+  Stream.EmitRecordWithBlob(TuUpdateLexicalAbbrev, Record,
+                            data(NewGlobalDecls));
+  
+  // And a visible updates block for the DeclContexts.
+  Abv = new llvm::BitCodeAbbrev();
+  Abv->Add(llvm::BitCodeAbbrevOp(UPDATE_VISIBLE));
+  Abv->Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::VBR, 6));
+  Abv->Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::Fixed, 32));
+  Abv->Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::Blob));
+  UpdateVisibleAbbrev = Stream.EmitAbbrev(Abv);
+  WriteDeclContextVisibleUpdate(TU);
+  
+  // If the translation unit has an anonymous namespace, write it as an
+  // update block.
+  if (NamespaceDecl *NS = TU->getAnonymousNamespace()) {
+    ASTWriter::UpdateRecord &Record = DeclUpdates[TU];
+    Record.push_back(UPD_CXX_ADDED_ANONYMOUS_NAMESPACE);
+    AddDeclRef(NS, Record);
+  }
+  
   // Keep writing types and declarations until all types and
   // declarations have been written.
   Stream.EnterSubblock(DECLTYPES_BLOCK_ID, NUM_ALLOWED_ABBREVS_SIZE);
@@ -3025,6 +3061,8 @@ void ASTWriter::WriteASTCore(Sema &SemaRef, MemorizeStatCalls *StatCalls,
   if (!KnownNamespaces.empty())
     Stream.EmitRecord(KNOWN_NAMESPACES, KnownNamespaces);
   
+  WriteDeclUpdatesBlocks();
+
   // Some simple statistics
   Record.clear();
   Record.push_back(NumStatements);
@@ -3042,6 +3080,9 @@ void ASTWriter::WriteASTChain(Sema &SemaRef, MemorizeStatCalls *StatCalls,
   ASTContext &Context = SemaRef.Context;
   Preprocessor &PP = SemaRef.PP;
 
+  // Set up predefined declaration IDs.
+  DeclIDs[Context.getTranslationUnitDecl()] = PREDEF_DECL_TRANSLATION_UNIT_ID;
+
   RecordData Record;
   Stream.EnterSubblock(AST_BLOCK_ID, 5);
   WriteMetadata(Context, isysroot, "");
diff --git a/lib/Serialization/ASTWriterDecl.cpp b/lib/Serialization/ASTWriterDecl.cpp
index 45f8a32df0..98dad1c90e 100644
--- a/lib/Serialization/ASTWriterDecl.cpp
+++ b/lib/Serialization/ASTWriterDecl.cpp
@@ -157,9 +157,7 @@ void ASTDeclWriter::VisitDecl(Decl *D) {
 }
 
 void ASTDeclWriter::VisitTranslationUnitDecl(TranslationUnitDecl *D) {
-  VisitDecl(D);
-  Writer.AddDeclRef(D->getAnonymousNamespace(), Record);
-  Code = serialization::DECL_TRANSLATION_UNIT;
+  llvm_unreachable("Translation units aren't directly serialized");
 }
 
 void ASTDeclWriter::VisitNamedDecl(NamedDecl *D) {
@@ -819,7 +817,7 @@ void ASTDeclWriter::VisitNamespaceDecl(NamespaceDecl *D) {
     // anonymous namespace.
     Decl *Parent = cast<Decl>(
         D->getParent()->getRedeclContext()->getPrimaryContext());
-    if (Parent->getPCHLevel() > 0) {
+    if (Parent->getPCHLevel() > 0 || isa<TranslationUnitDecl>(Parent)) {
       ASTWriter::UpdateRecord &Record = Writer.DeclUpdates[Parent];
       Record.push_back(UPD_CXX_ADDED_ANONYMOUS_NAMESPACE);
       Writer.AddDeclRef(D, Record);