Put the mechanism in place to track modifications in an AST entity that were committed after

its initial creation/deserialization and store the changes in a chained PCH.

The idea is that the AST entities call methods on the ASTMutationListener to give notifications
of changes; the PCHWriter implements the ASTMutationListener interface and stores the incremental changes
of the updated entity. WIP

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@117235 91177308-0d34-0410-b5e6-96231b3b80d8

8 files changed, 104 insertions, 16 deletions

diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index c7b014efb5..313c2ea96b 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -20,6 +20,7 @@
 #include "clang/AST/Expr.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/ExternalASTSource.h"
+#include "clang/AST/ASTMutationListener.h"
 #include "clang/AST/RecordLayout.h"
 #include "clang/Basic/Builtins.h"
 #include "clang/Basic/SourceManager.h"
@@ -5200,6 +5201,8 @@ ExternalASTSource::~ExternalASTSource() { }
 
 void ExternalASTSource::PrintStats() { }
 
+ASTMutationListener::~ASTMutationListener() { }
+
 
 //===----------------------------------------------------------------------===//
 //                          Builtin Type Computation
diff --git a/lib/AST/DeclBase.cpp b/lib/AST/DeclBase.cpp
index d60a06749d..483352f2d6 100644
--- a/lib/AST/DeclBase.cpp
+++ b/lib/AST/DeclBase.cpp
@@ -210,6 +210,10 @@ ASTContext &Decl::getASTContext() const {
   return getTranslationUnitDecl()->getASTContext();
 }
 
+ASTMutationListener *Decl::getASTMutationListener() const {
+  return getASTContext().getASTMutationListener();
+}
+
 bool Decl::isUsed(bool CheckUsedAttr) const { 
   if (Used)
     return true;
diff --git a/lib/AST/DeclCXX.cpp b/lib/AST/DeclCXX.cpp
index 8e1de4d027..f37151439f 100644
--- a/lib/AST/DeclCXX.cpp
+++ b/lib/AST/DeclCXX.cpp
@@ -14,6 +14,7 @@
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/AST/ASTContext.h"
+#include "clang/AST/ASTMutationListener.h"
 #include "clang/AST/CXXInheritance.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/TypeLoc.h"
diff --git a/lib/Frontend/FrontendAction.cpp b/lib/Frontend/FrontendAction.cpp
index 97188919f9..26ae4b1f7f 100644
--- a/lib/Frontend/FrontendAction.cpp
+++ b/lib/Frontend/FrontendAction.cpp
@@ -167,6 +167,8 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
 
     llvm::OwningPtr<ASTConsumer> Consumer(CreateASTConsumer(CI, Filename));
 
+    CI.getASTContext().setASTMutationListener(Consumer->GetASTMutationListener());
+
     /// Use PCH?
     if (!CI.getPreprocessorOpts().ImplicitPCHInclude.empty()) {
       assert(hasPCHSupport() && "This action does not have PCH support!");
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 162fa26e2d..38e786bff1 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -454,8 +454,6 @@ void PCHValidator::ReadCounter(unsigned Value) {
 void
 ASTReader::setDeserializationListener(ASTDeserializationListener *Listener) {
   DeserializationListener = Listener;
-  if (DeserializationListener)
-    DeserializationListener->SetReader(this);
 }
 
 
@@ -1716,6 +1714,13 @@ ASTReader::ReadASTBlock(PerFileData &F) {
         }
         break;
 
+      case DECL_UPDATES_BLOCK_ID:
+        if (Stream.SkipBlock()) {
+          Error("malformed block record in AST file");
+          return Failure;
+        }
+        break;
+
       case PREPROCESSOR_BLOCK_ID:
         F.MacroCursor = Stream;
         if (PP)
@@ -2043,6 +2048,17 @@ ASTReader::ReadASTBlock(PerFileData &F) {
       F.LocalNumMacroDefinitions = Record[1];
       break;
 
+    case DECL_UPDATE_OFFSETS: {
+      if (Record.size() % 2 != 0) {
+        Error("invalid DECL_UPDATE_OFFSETS block in AST file");
+        return Failure;
+      }
+      for (unsigned I = 0, N = Record.size(); I != N; I += 2)
+        DeclUpdateOffsets[static_cast<DeclID>(Record[I])]
+            .push_back(std::make_pair(&F, Record[I+1]));
+      break;
+    }
+
     case DECL_REPLACEMENTS: {
       if (Record.size() % 2 != 0) {
         Error("invalid DECL_REPLACEMENTS block in AST file");
@@ -2164,6 +2180,9 @@ ASTReader::ASTReadResult ASTReader::ReadAST(const std::string &FileName,
   if (Context)
     InitializeContext(*Context);
 
+  if (DeserializationListener)
+    DeserializationListener->ReaderInitialized(this);
+
   return Success;
 }
 
diff --git a/lib/Serialization/ASTReaderDecl.cpp b/lib/Serialization/ASTReaderDecl.cpp
index 750e7236ef..acc4dc144d 100644
--- a/lib/Serialization/ASTReaderDecl.cpp
+++ b/lib/Serialization/ASTReaderDecl.cpp
@@ -12,6 +12,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "ASTCommon.h"
 #include "clang/Serialization/ASTReader.h"
 #include "clang/AST/ASTConsumer.h"
 #include "clang/AST/ASTContext.h"
@@ -71,6 +72,8 @@ namespace clang {
 
     void Visit(Decl *D);
 
+    void UpdateDecl(Decl *D, const RecordData &Record);
+
     void VisitDecl(Decl *D);
     void VisitTranslationUnitDecl(TranslationUnitDecl *TU);
     void VisitNamedDecl(NamedDecl *ND);
@@ -1537,6 +1540,28 @@ Decl *ASTReader::ReadDeclRecord(unsigned Index, DeclID ID) {
   }
   assert(Idx == Record.size());
 
+  // 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.
+  DeclUpdateOffsetsMap::iterator UpdI = DeclUpdateOffsets.find(ID);
+  if (UpdI != DeclUpdateOffsets.end()) {
+    FileOffsetsTy &UpdateOffsets = UpdI->second;
+    for (FileOffsetsTy::iterator
+           I = UpdateOffsets.begin(), E = UpdateOffsets.end(); I != E; ++I) {
+      PerFileData *F = I->first;
+      uint64_t Offset = I->second;
+      llvm::BitstreamCursor &Cursor = F->DeclsCursor;
+      SavedStreamPosition SavedPosition(Cursor);
+      Cursor.JumpToBit(Offset);
+      RecordData Record;
+      unsigned Code = Cursor.ReadCode();
+      unsigned RecCode = Cursor.ReadRecord(Code, Record);
+      (void)RecCode;
+      assert(RecCode == DECL_UPDATES && "Expected DECL_UPDATES record!");
+      Reader.UpdateDecl(D, 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
@@ -1546,3 +1571,7 @@ Decl *ASTReader::ReadDeclRecord(unsigned Index, DeclID ID) {
 
   return D;
 }
+
+void ASTDeclReader::UpdateDecl(Decl *D, const RecordData &Record) {
+  // No update is tracked yet.
+}
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index 4d0ec99074..e258fcc2a2 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -2474,17 +2474,6 @@ void ASTWriter::WriteASTChain(Sema &SemaRef, MemorizeStatCalls *StatCalls,
                               const char *isysroot) {
   using namespace llvm;
 
-  FirstDeclID += Chain->getTotalNumDecls();
-  FirstTypeID += Chain->getTotalNumTypes();
-  FirstIdentID += Chain->getTotalNumIdentifiers();
-  FirstSelectorID += Chain->getTotalNumSelectors();
-  FirstMacroID += Chain->getTotalNumMacroDefinitions();
-  NextDeclID = FirstDeclID;
-  NextTypeID = FirstTypeID;
-  NextIdentID = FirstIdentID;
-  NextSelectorID = FirstSelectorID;
-  NextMacroID = FirstMacroID;
-
   ASTContext &Context = SemaRef.Context;
   Preprocessor &PP = SemaRef.PP;
 
@@ -2707,6 +2696,8 @@ void ASTWriter::WriteASTChain(Sema &SemaRef, MemorizeStatCalls *StatCalls,
   if (!AdditionalTemplateSpecializations.empty())
     WriteAdditionalTemplateSpecializations();
 
+  WriteDeclChangeSetBlocks();
+
   Record.clear();
   Record.push_back(NumStatements);
   Record.push_back(NumMacros);
@@ -2717,6 +2708,27 @@ void ASTWriter::WriteASTChain(Sema &SemaRef, MemorizeStatCalls *StatCalls,
   Stream.ExitBlock();
 }
 
+void ASTWriter::WriteDeclChangeSetBlocks() {
+  if (DeclUpdates.empty())
+    return;
+
+  RecordData OffsetsRecord;
+  Stream.EnterSubblock(DECL_UPDATES_BLOCK_ID, 3);
+  for (DeclUpdateMap::iterator
+         I = DeclUpdates.begin(), E = DeclUpdates.end(); I != E; ++I) {
+    const Decl *D = I->first;
+    UpdateRecord &URec = I->second;
+
+    uint64_t Offset = Stream.GetCurrentBitNo();
+    Stream.EmitRecord(DECL_UPDATES, URec);
+
+    OffsetsRecord.push_back(GetDeclRef(D));
+    OffsetsRecord.push_back(Offset);
+  }
+  Stream.ExitBlock();
+  Stream.EmitRecord(DECL_UPDATE_OFFSETS, OffsetsRecord);
+}
+
 void ASTWriter::WriteDeclUpdateBlock() {
   if (ReplacedDecls.empty())
     return;
@@ -2891,7 +2903,7 @@ TypeIdx ASTWriter::getTypeIdx(QualType T) const {
   return I->second;
 }
 
-void ASTWriter::AddDeclRef(const Decl *D, RecordData &Record) {
+void ASTWriter::AddDeclRef(const Decl *D, RecordDataImpl &Record) {
   Record.push_back(GetDeclRef(D));
 }
 
@@ -3190,8 +3202,9 @@ void ASTWriter::AddCXXBaseOrMemberInitializers(
   }
 }
 
-void ASTWriter::SetReader(ASTReader *Reader) {
+void ASTWriter::ReaderInitialized(ASTReader *Reader) {
   assert(Reader && "Cannot remove chain");
+  assert(!Chain && "Cannot replace chain");
   assert(FirstDeclID == NextDeclID &&
          FirstTypeID == NextTypeID &&
          FirstIdentID == NextIdentID &&
@@ -3199,6 +3212,17 @@ void ASTWriter::SetReader(ASTReader *Reader) {
          FirstMacroID == NextMacroID &&
          "Setting chain after writing has started.");
   Chain = Reader;
+
+  FirstDeclID += Chain->getTotalNumDecls();
+  FirstTypeID += Chain->getTotalNumTypes();
+  FirstIdentID += Chain->getTotalNumIdentifiers();
+  FirstSelectorID += Chain->getTotalNumSelectors();
+  FirstMacroID += Chain->getTotalNumMacroDefinitions();
+  NextDeclID = FirstDeclID;
+  NextTypeID = FirstTypeID;
+  NextIdentID = FirstIdentID;
+  NextSelectorID = FirstSelectorID;
+  NextMacroID = FirstMacroID;
 }
 
 void ASTWriter::IdentifierRead(IdentID ID, IdentifierInfo *II) {
diff --git a/lib/Serialization/GeneratePCH.cpp b/lib/Serialization/GeneratePCH.cpp
index 5329b6cbd4..0d8ec736b6 100644
--- a/lib/Serialization/GeneratePCH.cpp
+++ b/lib/Serialization/GeneratePCH.cpp
@@ -30,7 +30,7 @@ PCHGenerator::PCHGenerator(const Preprocessor &PP,
                            const char *isysroot,
                            llvm::raw_ostream *OS)
   : PP(PP), isysroot(isysroot), Out(OS), SemaPtr(0),
-    StatCalls(0), Stream(Buffer), Writer(Stream) {
+    StatCalls(0), Stream(Buffer), Writer(Stream), Chaining(Chaining) {
 
   // Install a stat() listener to keep track of all of the stat()
   // calls.
@@ -59,6 +59,12 @@ void PCHGenerator::HandleTranslationUnit(ASTContext &Ctx) {
   Buffer.clear();
 }
 
+ASTMutationListener *PCHGenerator::GetASTMutationListener() {
+  if (Chaining)
+    return &Writer;
+  return 0;
+}
+
 ASTDeserializationListener *PCHGenerator::GetASTDeserializationListener() {
   return &Writer;
 }