Modify the way sub-statements are stored and retrieved from PCH.

Before this commit, sub-stmts were stored as encountered and when they were placed in the Stmts stack we had to know what index
each stmt operand has. This complicated supporting variable sub-stmts and sub-stmts that were contained in TypeSourceInfos, e.g.

x = sizeof(int[1]);

would crash PCH.

Now, sub-stmts are stored in reverse order, from last to first, so that when reading them, in order to get the next sub-stmt we just
need to pop the last stmt from the stack. This greatly simplified the way stmts are written and read (just use PCHWriter::AddStmt and
 PCHReader::ReadStmt accordingly) and allowed variable stmt operands and TypeSourceInfo exprs.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@107087 91177308-0d34-0410-b5e6-96231b3b80d8

9 files changed, 529 insertions, 726 deletions

diff --git a/include/clang/Frontend/PCHReader.h b/include/clang/Frontend/PCHReader.h
index ff966b005f..22625dc508 100644
--- a/include/clang/Frontend/PCHReader.h
+++ b/include/clang/Frontend/PCHReader.h
@@ -449,6 +449,34 @@ private:
   /// Objective-C protocols.
   llvm::SmallVector<Decl *, 16> InterestingDecls;
 
+  /// \brief When reading a Stmt tree, Stmt operands are placed in this stack.
+  llvm::SmallVector<Stmt *, 16> StmtStack;
+
+  /// \brief What kind of records we are reading.
+  enum ReadingKind {
+    Read_Decl, Read_Type, Read_Stmt
+  };
+
+  /// \brief What kind of records we are reading. 
+  ReadingKind ReadingKind;
+
+  /// \brief RAII object to change the reading kind.
+  class ReadingKindTracker {
+    PCHReader &Reader;
+    enum ReadingKind PrevKind;
+
+    ReadingKindTracker(const ReadingKindTracker&); // do not implement
+    ReadingKindTracker &operator=(const ReadingKindTracker&);// do not implement
+
+  public:
+    ReadingKindTracker(enum ReadingKind newKind, PCHReader &reader)
+      : Reader(reader), PrevKind(Reader.ReadingKind) {
+      Reader.ReadingKind = newKind;
+    }
+
+    ~ReadingKindTracker() { Reader.ReadingKind = PrevKind; }
+  };
+
   /// \brief The file ID for the predefines buffer in the PCH file.
   FileID PCHPredefinesBufferID;
 
@@ -469,6 +497,9 @@ private:
   /// predefines buffer may contain additional definitions.
   std::string SuggestedPredefines;
 
+  /// \brief Reads a statement from the specified cursor.
+  Stmt *ReadStmtFromStream(llvm::BitstreamCursor &Cursor);
+
   void MaybeAddSystemRootToFilename(std::string &Filename);
 
   PCHReadResult ReadPCHBlock();
@@ -563,19 +594,6 @@ public:
   /// \brief Read preprocessed entities into the 
   virtual void ReadPreprocessedEntities();
 
-  /// \brief Abstract interface for reading expressions.
-  class ExprReader {
-  public:
-    virtual Expr *Read();
-  };
-
-  /// \brief Reads a TemplateArgumentLocInfo appropriate for the
-  /// given TemplateArgument kind.
-  TemplateArgumentLocInfo
-  GetTemplateArgumentLocInfo(TemplateArgument::ArgKind Kind,
-                             const RecordData &Record, unsigned &Idx,
-                             ExprReader &ExprRdr);
-
   /// \brief Reads a TemplateArgumentLocInfo appropriate for the
   /// given TemplateArgument kind.
   TemplateArgumentLocInfo
@@ -584,11 +602,6 @@ public:
 
   /// \brief Reads a TemplateArgumentLoc.
   TemplateArgumentLoc ReadTemplateArgumentLoc(const RecordData &Record,
-                                              unsigned &Idx,
-                                              ExprReader &ExprRdr);
-
-  /// \brief Reads a TemplateArgumentLoc.
-  TemplateArgumentLoc ReadTemplateArgumentLoc(const RecordData &Record,
                                               unsigned &Idx);
 
   /// \brief Reads a declarator info from the given record.
@@ -719,10 +732,6 @@ public:
   TemplateName ReadTemplateName(const RecordData &Record, unsigned &Idx);
 
   /// \brief Read a template argument.
-  TemplateArgument ReadTemplateArgument(const RecordData &Record,unsigned &Idx,
-                                        ExprReader &ExprRdr);
-
-  /// \brief Read a template argument.
   TemplateArgument ReadTemplateArgument(const RecordData &Record,unsigned &Idx);
   
   /// \brief Read a template parameter list.
@@ -759,19 +768,11 @@ public:
   /// \brief Reads attributes from the current stream position.
   Attr *ReadAttributes();
 
-  /// \brief ReadDeclExpr - Reads an expression from the current decl cursor.
-  Expr *ReadDeclExpr();
-
-  /// \brief ReadTypeExpr - Reads an expression from the current type cursor.
-  Expr *ReadTypeExpr();
+  /// \brief Reads a statement.
+  Stmt *ReadStmt();
 
-  /// \brief Reads a statement from the specified cursor.
-  Stmt *ReadStmt(llvm::BitstreamCursor &Cursor);
-
-  /// \brief Read a statement from the current DeclCursor.
-  Stmt *ReadDeclStmt() {
-    return ReadStmt(DeclsCursor);
-  }
+  /// \brief Reads an expression.
+  Expr *ReadExpr();
 
   /// \brief Reads the macro record located at the given offset.
   void ReadMacroRecord(uint64_t Offset);
diff --git a/include/clang/Frontend/PCHWriter.h b/include/clang/Frontend/PCHWriter.h
index dffda371b4..dddbf85b29 100644
--- a/include/clang/Frontend/PCHWriter.h
+++ b/include/clang/Frontend/PCHWriter.h
@@ -189,7 +189,11 @@ private:
 
   /// \brief Statements that we've encountered while serializing a
   /// declaration or type.
-  llvm::SmallVector<Stmt *, 8> StmtsToEmit;
+  llvm::SmallVector<Stmt *, 16> StmtsToEmit;
+  
+  /// \brief Statements collection to use for PCHWriter::AddStmt().
+  /// It will point to StmtsToEmit unless it is overriden. 
+  llvm::SmallVector<Stmt *, 16> *CollectedStmts;
 
   /// \brief Mapping from SwitchCase statements to IDs.
   std::map<SwitchCase *, unsigned> SwitchCaseIDs;
@@ -211,8 +215,8 @@ private:
   /// file.
   unsigned NumVisibleDeclContexts;
 
-  /// \brief True when we are in Stmts emitting mode.
-  bool EmittingStmts;
+  /// \brief Write the given subexpression to the bitstream.
+  void WriteSubStmt(Stmt *S);
 
   void WriteBlockInfoBlock();
   void WriteMetadata(ASTContext &Context, const char *isysroot);
@@ -359,15 +363,9 @@ public:
   /// the corresponding statements just after the type or
   /// declaration.
   void AddStmt(Stmt *S) {
-    if (EmittingStmts)
-      WriteSubStmt(S);
-    else
-      StmtsToEmit.push_back(S);
+      CollectedStmts->push_back(S);
   }
 
-  /// \brief Write the given subexpression to the bitstream.
-  void WriteSubStmt(Stmt *S);
-
   /// \brief Flush all of the statements and expressions that have
   /// been added to the queue via AddStmt().
   void FlushStmts();
diff --git a/lib/Frontend/PCHReader.cpp b/lib/Frontend/PCHReader.cpp
index 5628de3829..a526fd6dc5 100644
--- a/lib/Frontend/PCHReader.cpp
+++ b/lib/Frontend/PCHReader.cpp
@@ -321,18 +321,6 @@ void PCHValidator::ReadCounter(unsigned Value) {
 // PCH reader implementation
 //===----------------------------------------------------------------------===//
 
-// Give ExprReader's VTable a home.
-Expr *PCHReader::ExprReader::Read() { return 0; }
-
-namespace {
-  class DeclExprReader : public PCHReader::ExprReader {
-    PCHReader &Reader;
-  public:
-    DeclExprReader(PCHReader &reader) : Reader(reader) { }
-    virtual Expr *Read() { return Reader.ReadDeclExpr(); }
-  };
-} // anonymous namespace
-
 PCHReader::PCHReader(Preprocessor &PP, ASTContext *Context,
                      const char *isysroot)
   : Listener(new PCHValidator(PP, *this)), SourceMgr(PP.getSourceManager()),
@@ -372,14 +360,6 @@ PCHReader::PCHReader(SourceManager &SourceMgr, FileManager &FileMgr,
 
 PCHReader::~PCHReader() {}
 
-Expr *PCHReader::ReadDeclExpr() {
-  return dyn_cast_or_null<Expr>(ReadStmt(DeclsCursor));
-}
-
-Expr *PCHReader::ReadTypeExpr() {
-  return dyn_cast_or_null<Expr>(ReadStmt(DeclsCursor));
-}
-
 
 namespace {
 class PCHMethodPoolLookupTrait {
@@ -1969,6 +1949,8 @@ QualType PCHReader::ReadTypeRecord(uint64_t Offset) {
   // after reading this type.
   SavedStreamPosition SavedPosition(DeclsCursor);
 
+  ReadingKindTracker ReadingKind(Read_Type, *this);
+  
   // Note that we are loading a type record.
   LoadingTypeOrDecl Loading(*this);
 
@@ -2064,7 +2046,7 @@ QualType PCHReader::ReadTypeRecord(uint64_t Offset) {
     unsigned IndexTypeQuals = Record[2];
     SourceLocation LBLoc = SourceLocation::getFromRawEncoding(Record[3]);
     SourceLocation RBLoc = SourceLocation::getFromRawEncoding(Record[4]);
-    return Context->getVariableArrayType(ElementType, ReadTypeExpr(),
+    return Context->getVariableArrayType(ElementType, ReadExpr(),
                                          ASM, IndexTypeQuals,
                                          SourceRange(LBLoc, RBLoc));
   }
@@ -2141,7 +2123,7 @@ QualType PCHReader::ReadTypeRecord(uint64_t Offset) {
     return Context->getTypeDeclType(cast<TypedefDecl>(GetDecl(Record[0])));
 
   case pch::TYPE_TYPEOF_EXPR:
-    return Context->getTypeOfExprType(ReadTypeExpr());
+    return Context->getTypeOfExprType(ReadExpr());
 
   case pch::TYPE_TYPEOF: {
     if (Record.size() != 1) {
@@ -2153,7 +2135,7 @@ QualType PCHReader::ReadTypeRecord(uint64_t Offset) {
   }
 
   case pch::TYPE_DECLTYPE:
-    return Context->getDecltypeType(ReadTypeExpr());
+    return Context->getDecltypeType(ReadExpr());
 
   case pch::TYPE_RECORD:
     if (Record.size() != 1) {
@@ -2319,7 +2301,7 @@ void TypeLocReader::VisitArrayTypeLoc(ArrayTypeLoc TL) {
   TL.setLBracketLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
   TL.setRBracketLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
   if (Record[Idx++])
-    TL.setSizeExpr(Reader.ReadDeclExpr());
+    TL.setSizeExpr(Reader.ReadExpr());
   else
     TL.setSizeExpr(0);
 }
@@ -2511,10 +2493,10 @@ QualType PCHReader::GetType(pch::TypeID ID) {
 TemplateArgumentLocInfo
 PCHReader::GetTemplateArgumentLocInfo(TemplateArgument::ArgKind Kind,
                                       const RecordData &Record,
-                                      unsigned &Index, ExprReader &ExprRdr) {
+                                      unsigned &Index) {
   switch (Kind) {
   case TemplateArgument::Expression:
-    return ExprRdr.Read();
+    return ReadExpr();
   case TemplateArgument::Type:
     return GetTypeSourceInfo(Record, Index);
   case TemplateArgument::Template: {
@@ -2532,32 +2514,16 @@ PCHReader::GetTemplateArgumentLocInfo(TemplateArgument::ArgKind Kind,
   return TemplateArgumentLocInfo();
 }
 
-TemplateArgumentLocInfo
-PCHReader::GetTemplateArgumentLocInfo(TemplateArgument::ArgKind Kind,
-                                      const RecordData &Record,
-                                      unsigned &Index) {
-  DeclExprReader DeclExprReader(*this);
-  return GetTemplateArgumentLocInfo(Kind, Record, Index, DeclExprReader);
-}
-
 TemplateArgumentLoc
-PCHReader::ReadTemplateArgumentLoc(const RecordData &Record, unsigned &Index,
-                                   ExprReader &ExprRdr) {
-  TemplateArgument Arg = ReadTemplateArgument(Record, Index, ExprRdr);
+PCHReader::ReadTemplateArgumentLoc(const RecordData &Record, unsigned &Index) {
+  TemplateArgument Arg = ReadTemplateArgument(Record, Index);
 
   if (Arg.getKind() == TemplateArgument::Expression) {
     if (Record[Index++]) // bool InfoHasSameExpr.
       return TemplateArgumentLoc(Arg, TemplateArgumentLocInfo(Arg.getAsExpr()));
   }
   return TemplateArgumentLoc(Arg, GetTemplateArgumentLocInfo(Arg.getKind(),
-                                                             Record, Index,
-                                                             ExprRdr));
-}
-
-TemplateArgumentLoc
-PCHReader::ReadTemplateArgumentLoc(const RecordData &Record, unsigned &Index) {
-  DeclExprReader DeclExprReader(*this);
-  return ReadTemplateArgumentLoc(Record, Index, DeclExprReader);
+                                                             Record, Index));
 }
 
 Decl *PCHReader::GetExternalDecl(uint32_t ID) {
@@ -2589,7 +2555,7 @@ Stmt *PCHReader::GetExternalDeclStmt(uint64_t Offset) {
   // Since we know tha this statement is part of a decl, make sure to use the
   // decl cursor to read it.
   DeclsCursor.JumpToBit(Offset);
-  return ReadStmt(DeclsCursor);
+  return ReadStmtFromStream(DeclsCursor);
 }
 
 bool PCHReader::FindExternalLexicalDecls(const DeclContext *DC,
@@ -3034,8 +3000,7 @@ PCHReader::ReadTemplateName(const RecordData &Record, unsigned &Idx) {
 }
 
 TemplateArgument
-PCHReader::ReadTemplateArgument(const RecordData &Record, unsigned &Idx,
-                                ExprReader &ExprRdr) {
+PCHReader::ReadTemplateArgument(const RecordData &Record, unsigned &Idx) {
   switch ((TemplateArgument::ArgKind)Record[Idx++]) {
   case TemplateArgument::Null:
     return TemplateArgument();
@@ -3051,13 +3016,13 @@ PCHReader::ReadTemplateArgument(const RecordData &Record, unsigned &Idx,
   case TemplateArgument::Template:
     return TemplateArgument(ReadTemplateName(Record, Idx));
   case TemplateArgument::Expression:
-    return TemplateArgument(ExprRdr.Read());
+    return TemplateArgument(ReadExpr());
   case TemplateArgument::Pack: {
     unsigned NumArgs = Record[Idx++];
     llvm::SmallVector<TemplateArgument, 8> Args;
     Args.reserve(NumArgs);
     while (NumArgs--)
-      Args.push_back(ReadTemplateArgument(Record, Idx, ExprRdr));
+      Args.push_back(ReadTemplateArgument(Record, Idx));
     TemplateArgument TemplArg;
     TemplArg.setArgumentPack(Args.data(), Args.size(), /*CopyArgs=*/true);
     return TemplArg;
@@ -3068,12 +3033,6 @@ PCHReader::ReadTemplateArgument(const RecordData &Record, unsigned &Idx,
   return TemplateArgument();
 }
 
-TemplateArgument
-PCHReader::ReadTemplateArgument(const RecordData &Record, unsigned &Idx) {
-  DeclExprReader DeclExprReader(*this);
-  return ReadTemplateArgument(Record, Idx, DeclExprReader);
-}
-
 TemplateParameterList *
 PCHReader::ReadTemplateParameterList(const RecordData &Record, unsigned &Idx) {
   SourceLocation TemplateLoc = ReadSourceLocation(Record, Idx);
diff --git a/lib/Frontend/PCHReaderDecl.cpp b/lib/Frontend/PCHReaderDecl.cpp
index d7c5d77eb9..05cefa9ffe 100644
--- a/lib/Frontend/PCHReaderDecl.cpp
+++ b/lib/Frontend/PCHReaderDecl.cpp
@@ -184,7 +184,7 @@ void PCHDeclReader::VisitValueDecl(ValueDecl *VD) {
 void PCHDeclReader::VisitEnumConstantDecl(EnumConstantDecl *ECD) {
   VisitValueDecl(ECD);
   if (Record[Idx++])
-    ECD->setInitExpr(Reader.ReadDeclExpr());
+    ECD->setInitExpr(Reader.ReadExpr());
   ECD->setInitVal(Reader.ReadAPSInt(Record, Idx));
 }
 
@@ -299,7 +299,7 @@ void PCHDeclReader::VisitObjCMethodDecl(ObjCMethodDecl *MD) {
   if (Record[Idx++]) {
     // In practice, this won't be executed (since method definitions
     // don't occur in header files).
-    MD->setBody(Reader.ReadDeclStmt());
+    MD->setBody(Reader.ReadStmt());
     MD->setSelfDecl(cast<ImplicitParamDecl>(Reader.GetDecl(Record[Idx++])));
     MD->setCmdDecl(cast<ImplicitParamDecl>(Reader.GetDecl(Record[Idx++])));
   }
@@ -493,7 +493,7 @@ void PCHDeclReader::VisitFieldDecl(FieldDecl *FD) {
   VisitDeclaratorDecl(FD);
   FD->setMutable(Record[Idx++]);
   if (Record[Idx++])
-    FD->setBitWidth(Reader.ReadDeclExpr());
+    FD->setBitWidth(Reader.ReadExpr());
 }
 
 void PCHDeclReader::VisitVarDecl(VarDecl *VD) {
@@ -508,7 +508,7 @@ void PCHDeclReader::VisitVarDecl(VarDecl *VD) {
   VD->setPreviousDeclaration(
                          cast_or_null<VarDecl>(Reader.GetDecl(Record[Idx++])));
   if (Record[Idx++])
-    VD->setInit(Reader.ReadDeclExpr());
+    VD->setInit(Reader.ReadExpr());
 }
 
 void PCHDeclReader::VisitImplicitParamDecl(ImplicitParamDecl *PD) {
@@ -523,12 +523,12 @@ void PCHDeclReader::VisitParmVarDecl(ParmVarDecl *PD) {
 
 void PCHDeclReader::VisitFileScopeAsmDecl(FileScopeAsmDecl *AD) {
   VisitDecl(AD);
-  AD->setAsmString(cast<StringLiteral>(Reader.ReadDeclExpr()));
+  AD->setAsmString(cast<StringLiteral>(Reader.ReadExpr()));
 }
 
 void PCHDeclReader::VisitBlockDecl(BlockDecl *BD) {
   VisitDecl(BD);
-  BD->setBody(cast_or_null<CompoundStmt>(Reader.ReadDeclStmt()));
+  BD->setBody(cast_or_null<CompoundStmt>(Reader.ReadStmt()));
   BD->setSignatureAsWritten(Reader.GetTypeSourceInfo(Record, Idx));
   unsigned NumParams = Record[Idx++];
   llvm::SmallVector<ParmVarDecl *, 16> Params;
@@ -861,7 +861,7 @@ void PCHDeclReader::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
   D->setPosition(Record[Idx++]);
   // Rest of NonTypeTemplateParmDecl.
   if (Record[Idx++]) {
-    Expr *DefArg = Reader.ReadDeclExpr();
+    Expr *DefArg = Reader.ReadExpr();
     bool Inherited = Record[Idx++];
     D->setDefaultArgument(DefArg, Inherited);
  }
@@ -1106,6 +1106,8 @@ Decl *PCHReader::ReadDeclRecord(uint64_t Offset, unsigned Index) {
   // after reading this declaration.
   SavedStreamPosition SavedPosition(DeclsCursor);
 
+  ReadingKindTracker ReadingKind(Read_Decl, *this);
+
   // Note that we are loading a declaration record.
   LoadingTypeOrDecl Loading(*this);
 
diff --git a/lib/Frontend/PCHReaderStmt.cpp b/lib/Frontend/PCHReaderStmt.cpp
index 5f27a7da9a..e3ad266350 100644
--- a/lib/Frontend/PCHReaderStmt.cpp
+++ b/lib/Frontend/PCHReaderStmt.cpp
@@ -19,16 +19,15 @@ using namespace clang;
 
 namespace {
 
-  class PCHStmtReader : public StmtVisitor<PCHStmtReader, unsigned> {
+  class PCHStmtReader : public StmtVisitor<PCHStmtReader> {
     PCHReader &Reader;
     const PCHReader::RecordData &Record;
     unsigned &Idx;
-    llvm::SmallVectorImpl<Stmt *> &StmtStack;
 
   public:
     PCHStmtReader(PCHReader &Reader, const PCHReader::RecordData &Record,
-                  unsigned &Idx, llvm::SmallVectorImpl<Stmt *> &StmtStack)
-      : Reader(Reader), Record(Record), Idx(Idx), StmtStack(StmtStack) { }
+                  unsigned &Idx)
+      : Reader(Reader), Record(Record), Idx(Idx) { }
 
     /// \brief The number of record fields required for the Stmt class
     /// itself.
@@ -39,225 +38,194 @@ namespace {
     static const unsigned NumExprFields = NumStmtFields + 3;
     
     /// \brief Read and initialize a ExplicitTemplateArgumentList structure.
-    /// \return the number of Exprs that were read.
-    unsigned
-    ReadExplicitTemplateArgumentList(ExplicitTemplateArgumentList &ArgList,
-                                     unsigned NumTemplateArgs,
-                            llvm::SmallVectorImpl<Stmt *>::iterator EndOfExprs);
-
-    // Each of the Visit* functions reads in part of the expression
-    // from the given record and the current expression stack, then
-    // return the total number of operands that it read from the
-    // expression stack.
-
-    unsigned VisitStmt(Stmt *S);
-    unsigned VisitNullStmt(NullStmt *S);
-    unsigned VisitCompoundStmt(CompoundStmt *S);
-    unsigned VisitSwitchCase(SwitchCase *S);
-    unsigned VisitCaseStmt(CaseStmt *S);
-    unsigned VisitDefaultStmt(DefaultStmt *S);
-    unsigned VisitLabelStmt(LabelStmt *S);
-    unsigned VisitIfStmt(IfStmt *S);
-    unsigned VisitSwitchStmt(SwitchStmt *S);
-    unsigned VisitWhileStmt(WhileStmt *S);
-    unsigned VisitDoStmt(DoStmt *S);
-    unsigned VisitForStmt(ForStmt *S);
-    unsigned VisitGotoStmt(GotoStmt *S);
-    unsigned VisitIndirectGotoStmt(IndirectGotoStmt *S);
-    unsigned VisitContinueStmt(ContinueStmt *S);
-    unsigned VisitBreakStmt(BreakStmt *S);
-    unsigned VisitReturnStmt(ReturnStmt *S);
-    unsigned VisitDeclStmt(DeclStmt *S);
-    unsigned VisitAsmStmt(AsmStmt *S);
-    unsigned VisitExpr(Expr *E);
-    unsigned VisitPredefinedExpr(PredefinedExpr *E);
-    unsigned VisitDeclRefExpr(DeclRefExpr *E);
-    unsigned VisitIntegerLiteral(IntegerLiteral *E);
-    unsigned VisitFloatingLiteral(FloatingLiteral *E);
-    unsigned VisitImaginaryLiteral(ImaginaryLiteral *E);
-    unsigned VisitStringLiteral(StringLiteral *E);
-    unsigned VisitCharacterLiteral(CharacterLiteral *E);
-    unsigned VisitParenExpr(ParenExpr *E);
-    unsigned VisitUnaryOperator(UnaryOperator *E);
-    unsigned VisitOffsetOfExpr(OffsetOfExpr *E);
-    unsigned VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E);
-    unsigned VisitArraySubscriptExpr(ArraySubscriptExpr *E);
-    unsigned VisitCallExpr(CallExpr *E);
-    unsigned VisitMemberExpr(MemberExpr *E);
-    unsigned VisitCastExpr(CastExpr *E);
-    unsigned VisitBinaryOperator(BinaryOperator *E);
-    unsigned VisitCompoundAssignOperator(CompoundAssignOperator *E);
-    unsigned VisitConditionalOperator(ConditionalOperator *E);
-    unsigned VisitImplicitCastExpr(ImplicitCastExpr *E);
-    unsigned VisitExplicitCastExpr(ExplicitCastExpr *E);
-    unsigned VisitCStyleCastExpr(CStyleCastExpr *E);
-    unsigned VisitCompoundLiteralExpr(CompoundLiteralExpr *E);
-    unsigned VisitExtVectorElementExpr(ExtVectorElementExpr *E);
-    unsigned VisitInitListExpr(InitListExpr *E);
-    unsigned VisitDesignatedInitExpr(DesignatedInitExpr *E);
-    unsigned VisitImplicitValueInitExpr(ImplicitValueInitExpr *E);
-    unsigned VisitVAArgExpr(VAArgExpr *E);
-    unsigned VisitAddrLabelExpr(AddrLabelExpr *E);
-    unsigned VisitStmtExpr(StmtExpr *E);
-    unsigned VisitTypesCompatibleExpr(TypesCompatibleExpr *E);
-    unsigned VisitChooseExpr(ChooseExpr *E);
-    unsigned VisitGNUNullExpr(GNUNullExpr *E);
-    unsigned VisitShuffleVectorExpr(ShuffleVectorExpr *E);
-    unsigned VisitBlockExpr(BlockExpr *E);
-    unsigned VisitBlockDeclRefExpr(BlockDeclRefExpr *E);
-    unsigned VisitObjCStringLiteral(ObjCStringLiteral *E);
-    unsigned VisitObjCEncodeExpr(ObjCEncodeExpr *E);
-    unsigned VisitObjCSelectorExpr(ObjCSelectorExpr *E);
-    unsigned VisitObjCProtocolExpr(ObjCProtocolExpr *E);
-    unsigned VisitObjCIvarRefExpr(ObjCIvarRefExpr *E);
-    unsigned VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E);
-    unsigned VisitObjCImplicitSetterGetterRefExpr(
+    void ReadExplicitTemplateArgumentList(ExplicitTemplateArgumentList &ArgList,
+                                          unsigned NumTemplateArgs);
+
+    void VisitStmt(Stmt *S);
+    void VisitNullStmt(NullStmt *S);
+    void VisitCompoundStmt(CompoundStmt *S);
+    void VisitSwitchCase(SwitchCase *S);
+    void VisitCaseStmt(CaseStmt *S);
+    void VisitDefaultStmt(DefaultStmt *S);
+    void VisitLabelStmt(LabelStmt *S);
+    void VisitIfStmt(IfStmt *S);
+    void VisitSwitchStmt(SwitchStmt *S);
+    void VisitWhileStmt(WhileStmt *S);
+    void VisitDoStmt(DoStmt *S);
+    void VisitForStmt(ForStmt *S);
+    void VisitGotoStmt(GotoStmt *S);
+    void VisitIndirectGotoStmt(IndirectGotoStmt *S);
+    void VisitContinueStmt(ContinueStmt *S);
+    void VisitBreakStmt(BreakStmt *S);
+    void VisitReturnStmt(ReturnStmt *S);
+    void VisitDeclStmt(DeclStmt *S);
+    void VisitAsmStmt(AsmStmt *S);
+    void VisitExpr(Expr *E);
+    void VisitPredefinedExpr(PredefinedExpr *E);
+    void VisitDeclRefExpr(DeclRefExpr *E);
+    void VisitIntegerLiteral(IntegerLiteral *E);
+    void VisitFloatingLiteral(FloatingLiteral *E);
+    void VisitImaginaryLiteral(ImaginaryLiteral *E);
+    void VisitStringLiteral(StringLiteral *E);
+    void VisitCharacterLiteral(CharacterLiteral *E);
+    void VisitParenExpr(ParenExpr *E);
+    void VisitUnaryOperator(UnaryOperator *E);
+    void VisitOffsetOfExpr(OffsetOfExpr *E);
+    void VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E);
+    void VisitArraySubscriptExpr(ArraySubscriptExpr *E);
+    void VisitCallExpr(CallExpr *E);
+    void VisitMemberExpr(MemberExpr *E);
+    void VisitCastExpr(CastExpr *E);
+    void VisitBinaryOperator(BinaryOperator *E);
+    void VisitCompoundAssignOperator(CompoundAssignOperator *E);
+    void VisitConditionalOperator(ConditionalOperator *E);
+    void VisitImplicitCastExpr(ImplicitCastExpr *E);
+    void VisitExplicitCastExpr(ExplicitCastExpr *E);
+    void VisitCStyleCastExpr(CStyleCastExpr *E);
+    void VisitCompoundLiteralExpr(CompoundLiteralExpr *E);
+    void VisitExtVectorElementExpr(ExtVectorElementExpr *E);
+    void VisitInitListExpr(InitListExpr *E);
+    void VisitDesignatedInitExpr(DesignatedInitExpr *E);
+    void VisitImplicitValueInitExpr(ImplicitValueInitExpr *E);
+    void VisitVAArgExpr(VAArgExpr *E);
+    void VisitAddrLabelExpr(AddrLabelExpr *E);
+    void VisitStmtExpr(StmtExpr *E);
+    void VisitTypesCompatibleExpr(TypesCompatibleExpr *E);
+    void VisitChooseExpr(ChooseExpr *E);
+    void VisitGNUNullExpr(GNUNullExpr *E);
+    void VisitShuffleVectorExpr(ShuffleVectorExpr *E);
+    void VisitBlockExpr(BlockExpr *E);
+    void VisitBlockDeclRefExpr(BlockDeclRefExpr *E);
+    void VisitObjCStringLiteral(ObjCStringLiteral *E);
+    void VisitObjCEncodeExpr(ObjCEncodeExpr *E);
+    void VisitObjCSelectorExpr(ObjCSelectorExpr *E);
+    void VisitObjCProtocolExpr(ObjCProtocolExpr *E);
+    void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E);
+    void VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E);
+    void VisitObjCImplicitSetterGetterRefExpr(
                             ObjCImplicitSetterGetterRefExpr *E);
-    unsigned VisitObjCMessageExpr(ObjCMessageExpr *E);
-    unsigned VisitObjCSuperExpr(ObjCSuperExpr *E);
-    unsigned VisitObjCIsaExpr(ObjCIsaExpr *E);
-
-    unsigned VisitObjCForCollectionStmt(ObjCForCollectionStmt *);
-    unsigned VisitObjCAtCatchStmt(ObjCAtCatchStmt *);
-    unsigned VisitObjCAtFinallyStmt(ObjCAtFinallyStmt *);
-    unsigned VisitObjCAtTryStmt(ObjCAtTryStmt *);
-    unsigned VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *);
-    unsigned VisitObjCAtThrowStmt(ObjCAtThrowStmt *);
-
-    unsigned VisitCXXOperatorCallExpr(CXXOperatorCallExpr *E);
-    unsigned VisitCXXConstructExpr(CXXConstructExpr *E);
-    unsigned VisitCXXNamedCastExpr(CXXNamedCastExpr *E);
-    unsigned VisitCXXStaticCastExpr(CXXStaticCastExpr *E);
-    unsigned VisitCXXDynamicCastExpr(CXXDynamicCastExpr *E);
-    unsigned VisitCXXReinterpretCastExpr(CXXReinterpretCastExpr *E);
-    unsigned VisitCXXConstCastExpr(CXXConstCastExpr *E);
-    unsigned VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr *E);
-    unsigned VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E);
-    unsigned VisitCXXNullPtrLiteralExpr(CXXNullPtrLiteralExpr *E);
-    unsigned VisitCXXTypeidExpr(CXXTypeidExpr *E);
-    unsigned VisitCXXThisExpr(CXXThisExpr *E);
-    unsigned VisitCXXThrowExpr(CXXThrowExpr *E);
-    unsigned VisitCXXDefaultArgExpr(CXXDefaultArgExpr *E);
-    unsigned VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
+    void VisitObjCMessageExpr(ObjCMessageExpr *E);
+    void VisitObjCSuperExpr(ObjCSuperExpr *E);
+    void VisitObjCIsaExpr(ObjCIsaExpr *E);
+
+    void VisitObjCForCollectionStmt(ObjCForCollectionStmt *);
+    void VisitObjCAtCatchStmt(ObjCAtCatchStmt *);
+    void VisitObjCAtFinallyStmt(ObjCAtFinallyStmt *);
+    void VisitObjCAtTryStmt(ObjCAtTryStmt *);
+    void VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *);
+    void VisitObjCAtThrowStmt(ObjCAtThrowStmt *);
+
+    void VisitCXXOperatorCallExpr(CXXOperatorCallExpr *E);
+    void VisitCXXConstructExpr(CXXConstructExpr *E);
+    void VisitCXXNamedCastExpr(CXXNamedCastExpr *E);
+    void VisitCXXStaticCastExpr(CXXStaticCastExpr *E);
+    void VisitCXXDynamicCastExpr(CXXDynamicCastExpr *E);
+    void VisitCXXReinterpretCastExpr(CXXReinterpretCastExpr *E);
+    void VisitCXXConstCastExpr(CXXConstCastExpr *E);
+    void VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr *E);
+    void VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E);
+    void VisitCXXNullPtrLiteralExpr(CXXNullPtrLiteralExpr *E);
+    void VisitCXXTypeidExpr(CXXTypeidExpr *E);
+    void VisitCXXThisExpr(CXXThisExpr *E);
+    void VisitCXXThrowExpr(CXXThrowExpr *E);
+    void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *E);
+    void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
     
-    unsigned VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E);
-    unsigned VisitCXXNewExpr(CXXNewExpr *E);
-    unsigned VisitCXXDeleteExpr(CXXDeleteExpr *E);
-    unsigned VisitCXXPseudoDestructorExpr(CXXPseudoDestructorExpr *E);
+    void VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E);
+    void VisitCXXNewExpr(CXXNewExpr *E);
+    void VisitCXXDeleteExpr(CXXDeleteExpr *E);
+    void VisitCXXPseudoDestructorExpr(CXXPseudoDestructorExpr *E);
     
-    unsigned VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E);
+    void VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E);
     
-    unsigned VisitCXXDependentScopeMemberExpr(CXXDependentScopeMemberExpr *E);
-    unsigned VisitDependentScopeDeclRefExpr(DependentScopeDeclRefExpr *E);
-    unsigned VisitCXXUnresolvedConstructExpr(CXXUnresolvedConstructExpr *E);
+    void VisitCXXDependentScopeMemberExpr(CXXDependentScopeMemberExpr *E);
+    void VisitDependentScopeDeclRefExpr(DependentScopeDeclRefExpr *E);
+    void VisitCXXUnresolvedConstructExpr(CXXUnresolvedConstructExpr *E);
 
-    unsigned VisitOverloadExpr(OverloadExpr *E);
-    unsigned VisitUnresolvedMemberExpr(UnresolvedMemberExpr *E);
-    unsigned VisitUnresolvedLookupExpr(UnresolvedLookupExpr *E);
+    void VisitOverloadExpr(OverloadExpr *E);
+    void VisitUnresolvedMemberExpr(UnresolvedMemberExpr *E);
+    void VisitUnresolvedLookupExpr(UnresolvedLookupExpr *E);
   };
 }
 
-unsigned PCHStmtReader::
+void PCHStmtReader::
 ReadExplicitTemplateArgumentList(ExplicitTemplateArgumentList &ArgList,
-                                 unsigned NumTemplateArgs,
-                           llvm::SmallVectorImpl<Stmt *>::iterator EndOfExprs) {
-
-  class StmtStackExprReader : public PCHReader::ExprReader {
-    llvm::SmallVectorImpl<Stmt *>::iterator StmtI;
-  public:
-    StmtStackExprReader(const llvm::SmallVectorImpl<Stmt *>::iterator &stmtI)
-      : StmtI(stmtI) { }
-    virtual Expr *Read() { return cast_or_null<Expr>(*StmtI++); }
-  };
-
-  unsigned NumExprs = Record[Idx++];
-  
+                                 unsigned NumTemplateArgs) {
   TemplateArgumentListInfo ArgInfo;
   ArgInfo.setLAngleLoc(Reader.ReadSourceLocation(Record, Idx));
   ArgInfo.setRAngleLoc(Reader.ReadSourceLocation(Record, Idx));
-  
-  StmtStackExprReader ExprReader(EndOfExprs - NumExprs);
   for (unsigned i = 0; i != NumTemplateArgs; ++i)
-    ArgInfo.addArgument(Reader.ReadTemplateArgumentLoc(Record, Idx,
-                                                       ExprReader));
+    ArgInfo.addArgument(Reader.ReadTemplateArgumentLoc(Record, Idx));
   ArgList.initializeFrom(ArgInfo);
-
-  return NumExprs;
 }
 
-unsigned PCHStmtReader::VisitStmt(Stmt *S) {
+void PCHStmtReader::VisitStmt(Stmt *S) {
   assert(Idx == NumStmtFields && "Incorrect statement field count");
-  return 0;
 }
 
-unsigned PCHStmtReader::VisitNullStmt(NullStmt *S) {
+void PCHStmtReader::VisitNullStmt(NullStmt *S) {
   VisitStmt(S);
   S->setSemiLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
-  return 0;
 }
 
-unsigned PCHStmtReader::VisitCompoundStmt(CompoundStmt *S) {
+void PCHStmtReader::VisitCompoundStmt(CompoundStmt *S) {
   VisitStmt(S);
+  llvm::SmallVector<Stmt *, 16> Stmts;
   unsigned NumStmts = Record[Idx++];
-  S->setStmts(*Reader.getContext(),
-              StmtStack.data() + StmtStack.size() - NumStmts, NumStmts);
+  while (NumStmts--)
+    Stmts.push_back(Reader.ReadStmt());
+  S->setStmts(*Reader.getContext(), Stmts.data(), Stmts.size());
   S->setLBracLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
   S->setRBracLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
-  return NumStmts;
 }
 
-unsigned PCHStmtReader::VisitSwitchCase(SwitchCase *S) {
+void PCHStmtReader::VisitSwitchCase(SwitchCase *S) {
   VisitStmt(S);
   Reader.RecordSwitchCaseID(S, Record[Idx++]);
-  return 0;
 }
 
-unsigned PCHStmtReader::VisitCaseStmt(CaseStmt *S) {
+void PCHStmtReader::VisitCaseStmt(CaseStmt *S) {
   VisitSwitchCase(S);
-  S->setLHS(cast<Expr>(StmtStack[StmtStack.size() - 3]));
-  S->setRHS(cast_or_null<Expr>(StmtStack[StmtStack.size() - 2]));
-  S->setSubStmt(StmtStack.back());
+  S->setLHS(Reader.ReadExpr());
+  S->setRHS(Reader.ReadExpr());
+  S->setSubStmt(Reader.ReadStmt());
   S->setCaseLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
   S->setEllipsisLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
   S->setColonLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
-  return 3;
 }
 
-unsigned PCHStmtReader::VisitDefaultStmt(DefaultStmt *S) {
+void PCHStmtReader::VisitDefaultStmt(DefaultStmt *S) {
   VisitSwitchCase(S);
-  S->setSubStmt(StmtStack.back());
+  S->setSubStmt(Reader.ReadStmt());
   S->setDefaultLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
   S->setColonLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
-  return 1;
 }
 
-unsigned PCHStmtReader::VisitLabelStmt(LabelStmt *S) {
+void PCHStmtReader::VisitLabelStmt(LabelStmt *S) {
   VisitStmt(S);
   S->setID(Reader.GetIdentifierInfo(Record, Idx));
-  S->setSubStmt(StmtStack.back());
+  S->setSubStmt(Reader.ReadStmt());
   S->setIdentLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
   Reader.RecordLabelStmt(S, Record[Idx++]);
-  return 1;
 }
 
-unsigned PCHStmtReader::VisitIfStmt(IfStmt *S) {
+void PCHStmtReader::VisitIfStmt(IfStmt *S) {
   VisitStmt(S);
   S->setConditionVariable(*Reader.getContext(),
                           cast_or_null<VarDecl>(Reader.GetDecl(Record[Idx++])));
-  S->setCond(cast<Expr>(StmtStack[StmtStack.size() - 3]));
-  S->setThen(StmtStack[StmtStack.size() - 2]);
-  S->setElse(StmtStack[StmtStack.size() - 1]);
+  S->setCond(Reader.ReadExpr());
+  S->setThen(Reader.ReadStmt());
+  S->setElse(Reader.ReadStmt());
   S->setIfLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
   S->setElseLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
-  return 3;
 }
 
-unsigned PCHStmtReader::VisitSwitchStmt(SwitchStmt *S) {
+void PCHStmtReader::VisitSwitchStmt(SwitchStmt *S) {
   VisitStmt(S);
   S->setConditionVariable(*Reader.getContext(),
                           cast_or_null<VarDecl>(Reader.GetDecl(Record[Idx++])));
-  S->setCond(cast<Expr>(StmtStack[StmtStack.size() - 2]));
-  S->setBody(StmtStack.back());
+  S->setCond(Reader.ReadExpr());
+  S->setBody(Reader.ReadStmt());
   S->setSwitchLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
   SwitchCase *PrevSC = 0;
   for (unsigned N = Record.size(); Idx != N; ++Idx) {
@@ -272,80 +240,71 @@ unsigned PCHStmtReader::VisitSwitchStmt(SwitchStmt *S) {
     SC->Retain();
     PrevSC = SC;
   }
-  return 2;
 }
 
-unsigned PCHStmtReader::VisitWhileStmt(WhileStmt *S) {
+void PCHStmtReader::VisitWhileStmt(WhileStmt *S) {
   VisitStmt(S);
   S->setConditionVariable(*Reader.getContext(),
                           cast_or_null<VarDecl>(Reader.GetDecl(Record[Idx++])));
-  S->setCond(cast_or_null<Expr>(StmtStack[StmtStack.size() - 2]));
-  S->setBody(StmtStack.back());
+  S->setCond(Reader.ReadExpr());
+  S->setBody(Reader.ReadStmt());
   S->setWhileLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
-  return 2;
 }
 
-unsigned PCHStmtReader::VisitDoStmt(DoStmt *S) {
+void PCHStmtReader::VisitDoStmt(DoStmt *S) {
   VisitStmt(S);
-  S->setCond(cast_or_null<Expr>(StmtStack[StmtStack.size() - 2]));
-  S->setBody(StmtStack.back());
+  S->setCond(Reader.ReadExpr());
+  S->setBody(Reader.ReadStmt());
   S->setDoLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
   S->setWhileLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
   S->setRParenLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
-  return 2;
 }
 
-unsigned PCHStmtReader::VisitForStmt(ForStmt *S) {
+void PCHStmtReader::VisitForStmt(ForStmt *S) {
   VisitStmt(S);
-  S->setInit(StmtStack[StmtStack.size() - 4]);
-  S->setCond(cast_or_null<Expr>(StmtStack[StmtStack.size() - 3]));
+  S->setInit(Reader.ReadStmt());
+  S->setCond(Reader.ReadExpr());
   S->setConditionVariable(*Reader.getContext(),
                           cast_or_null<VarDecl>(Reader.GetDecl(Record[Idx++])));
-  S->setInc(cast_or_null<Expr>(StmtStack[StmtStack.size() - 2]));
-  S->setBody(StmtStack.back());
+  S-