[modules] Improve abbreviations for C++:

 * Add abbreviation for CXXMethodDecl and for FunctionProtoType. These come up
   a *lot* in C++ modules.
 * Allow typedef declarations to use the abbreviation if they're class members,
   or if they're used.

In passing, add more record name records for Clang AST node kinds.

The downside is that we had already used up our allotment of 12 abbreviations,
so this pushes us to an extra bit on each record to support the extra abbrev
kinds, which increases file size by ~1%. This patch *barely* pays for that
through the other improvements, but we've got room for another 18 abbrevs,
so we should be able to make it much more profitable with future changes.

llvm-svn: 214024

diff --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
index 7541f24..2b18380 100644 (file)
--- a/clang/include/clang/Serialization/ASTBitCodes.h
+++ b/clang/include/clang/Serialization/ASTBitCodes.h
@@ -759,9 +759,6 @@ namespace clang {
     /// NUM_PREDEF_TYPE_IDs.
     const unsigned NUM_PREDEF_TYPE_IDS = 100;
 
-    /// \brief The number of allowed abbreviations in bits
-    const unsigned NUM_ALLOWED_ABBREVS_SIZE = 4;
-
     /// \brief Record codes for each kind of type.
     ///
     /// These constants describe the type records that can occur within a

diff --git a/clang/include/clang/Serialization/ASTWriter.h b/clang/include/clang/Serialization/ASTWriter.h
index ad6ecdd..8ecdda4 100644 (file)
--- a/clang/include/clang/Serialization/ASTWriter.h
+++ b/clang/include/clang/Serialization/ASTWriter.h
@@ -466,7 +466,12 @@ private:
   void WritePragmaDiagnosticMappings(const DiagnosticsEngine &Diag,
                                      bool isModule);
   void WriteCXXBaseSpecifiersOffsets();
+
+  unsigned TypeExtQualAbbrev;
+  unsigned TypeFunctionProtoAbbrev;
+  void WriteTypeAbbrevs();
   void WriteType(QualType T);
+
   uint32_t GenerateNameLookupTable(const DeclContext *DC,
                                    llvm::SmallVectorImpl<char> &LookupTable);
   uint64_t WriteDeclContextLexicalBlock(ASTContext &Context, DeclContext *DC);
@@ -503,8 +508,9 @@ private:
   unsigned DeclFieldAbbrev;
   unsigned DeclEnumAbbrev;
   unsigned DeclObjCIvarAbbrev;
+  unsigned DeclCXXMethodAbbrev;
 
-  void WriteDeclsBlockAbbrevs();
+  void WriteDeclAbbrevs();
   void WriteDecl(ASTContext &Context, Decl *D);
   void AddFunctionDefinition(const FunctionDecl *FD, RecordData &Record);
 
@@ -731,6 +737,13 @@ public:
 
   void ClearSwitchCaseIDs();
 
+  unsigned getTypeExtQualAbbrev() const {
+    return TypeExtQualAbbrev;
+  }
+  unsigned getTypeFunctionProtoAbbrev() const {
+    return TypeFunctionProtoAbbrev;
+  }
+
   unsigned getDeclParmVarAbbrev() const { return DeclParmVarAbbrev; }
   unsigned getDeclRefExprAbbrev() const { return DeclRefExprAbbrev; }
   unsigned getCharacterLiteralAbbrev() const { return CharacterLiteralAbbrev; }
@@ -741,6 +754,7 @@ public:
   unsigned getDeclFieldAbbrev() const { return DeclFieldAbbrev; }
   unsigned getDeclEnumAbbrev() const { return DeclEnumAbbrev; }
   unsigned getDeclObjCIvarAbbrev() const { return DeclObjCIvarAbbrev; }
+  unsigned getDeclCXXMethodAbbrev() const { return DeclCXXMethodAbbrev; }
 
   bool hasChain() const { return Chain; }
 

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 6ed41c3..679b500 100644 (file)
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -5262,10 +5262,6 @@ QualType ASTReader::readTypeRecord(unsigned Index) {
                                         /*produces*/ Record[5]);
 
     unsigned Idx = 6;
-    unsigned NumParams = Record[Idx++];
-    SmallVector<QualType, 16> ParamTypes;
-    for (unsigned I = 0; I != NumParams; ++I)
-      ParamTypes.push_back(readType(*Loc.F, Record, Idx));
 
     EPI.Variadic = Record[Idx++];
     EPI.HasTrailingReturn = Record[Idx++];
@@ -5273,6 +5269,12 @@ QualType ASTReader::readTypeRecord(unsigned Index) {
     EPI.RefQualifier = static_cast<RefQualifierKind>(Record[Idx++]);
     SmallVector<QualType, 8> ExceptionStorage;
     readExceptionSpec(*Loc.F, ExceptionStorage, EPI, Record, Idx);
+
+    unsigned NumParams = Record[Idx++];
+    SmallVector<QualType, 16> ParamTypes;
+    for (unsigned I = 0; I != NumParams; ++I)
+      ParamTypes.push_back(readType(*Loc.F, Record, Idx));
+
     return Context.getFunctionType(ResultType, ParamTypes, EPI);
   }
 

diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index ac38f30..2b096fc 100644 (file)
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -83,6 +83,8 @@ namespace {
   public:
     /// \brief Type code that corresponds to the record generated.
     TypeCode Code;
+    /// \brief Abbreviation to use for the record, if any.
+    unsigned AbbrevToUse;
 
     ASTTypeWriter(ASTWriter &Writer, ASTWriter::RecordDataImpl &Record)
       : Writer(Writer), Record(Record), Code(TYPE_EXT_QUAL) { }
@@ -190,6 +192,9 @@ void ASTTypeWriter::VisitFunctionType(const FunctionType *T) {
   // FIXME: need to stabilize encoding of calling convention...
   Record.push_back(C.getCC());
   Record.push_back(C.getProducesResult());
+
+  if (C.getHasRegParm() || C.getRegParm() || C.getProducesResult())
+    AbbrevToUse = 0;
 }
 
 void ASTTypeWriter::VisitFunctionNoProtoType(const FunctionNoProtoType *T) {
@@ -216,14 +221,21 @@ static void addExceptionSpec(ASTWriter &Writer, const FunctionProtoType *T,
 
 void ASTTypeWriter::VisitFunctionProtoType(const FunctionProtoType *T) {
   VisitFunctionType(T);
-  Record.push_back(T->getNumParams());
-  for (unsigned I = 0, N = T->getNumParams(); I != N; ++I)
-    Writer.AddTypeRef(T->getParamType(I), Record);
+
   Record.push_back(T->isVariadic());
   Record.push_back(T->hasTrailingReturn());
   Record.push_back(T->getTypeQuals());
   Record.push_back(static_cast<unsigned>(T->getRefQualifier()));
   addExceptionSpec(Writer, T, Record);
+
+  Record.push_back(T->getNumParams());
+  for (unsigned I = 0, N = T->getNumParams(); I != N; ++I)
+    Writer.AddTypeRef(T->getParamType(I), Record);
+
+  if (T->isVariadic() || T->hasTrailingReturn() || T->getTypeQuals() ||
+      T->getRefQualifier() || T->getExceptionSpecType() != EST_None)
+    AbbrevToUse = 0;
+
   Code = TYPE_FUNCTION_PROTO;
 }
 
@@ -649,6 +661,40 @@ void TypeLocWriter::VisitAtomicTypeLoc(AtomicTypeLoc TL) {
   Writer.AddSourceLocation(TL.getRParenLoc(), Record);
 }
 
+void ASTWriter::WriteTypeAbbrevs() {
+  using namespace llvm;
+
+  BitCodeAbbrev *Abv;
+
+  // Abbreviation for TYPE_EXT_QUAL
+  Abv = new BitCodeAbbrev();
+  Abv->Add(BitCodeAbbrevOp(serialization::TYPE_EXT_QUAL));
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Type
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 3));   // Quals
+  TypeExtQualAbbrev = Stream.EmitAbbrev(Abv);
+
+  // Abbreviation for TYPE_FUNCTION_PROTO
+  Abv = new BitCodeAbbrev();
+  Abv->Add(BitCodeAbbrevOp(serialization::TYPE_FUNCTION_PROTO));
+  // FunctionType
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // ReturnType
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // NoReturn
+  Abv->Add(BitCodeAbbrevOp(0));                         // HasRegParm
+  Abv->Add(BitCodeAbbrevOp(0));                         // RegParm
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // CC
+  Abv->Add(BitCodeAbbrevOp(0));                         // ProducesResult
+  // FunctionProtoType
+  Abv->Add(BitCodeAbbrevOp(0));                         // IsVariadic
+  Abv->Add(BitCodeAbbrevOp(0));                         // HasTrailingReturn
+  Abv->Add(BitCodeAbbrevOp(0));                         // TypeQuals
+  Abv->Add(BitCodeAbbrevOp(0));                         // RefQualifier
+  Abv->Add(BitCodeAbbrevOp(EST_None));                  // ExceptionSpec
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // NumParams
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Params
+  TypeFunctionProtoAbbrev = Stream.EmitAbbrev(Abv);
+}
+
 //===----------------------------------------------------------------------===//
 // ASTWriter Implementation
 //===----------------------------------------------------------------------===//
@@ -684,6 +730,7 @@ static void AddStmtsExprs(llvm::BitstreamWriter &Stream,
 #define RECORD(X) EmitRecordID(X, #X, Stream, Record)
   RECORD(STMT_STOP);
   RECORD(STMT_NULL_PTR);
+  RECORD(STMT_REF_PTR);
   RECORD(STMT_NULL);
   RECORD(STMT_COMPOUND);
   RECORD(STMT_CASE);
@@ -752,6 +799,9 @@ static void AddStmtsExprs(llvm::BitstreamWriter &Stream,
   RECORD(STMT_OBJC_AT_SYNCHRONIZED);
   RECORD(STMT_OBJC_AT_THROW);
   RECORD(EXPR_OBJC_BOOL_LITERAL);
+  RECORD(STMT_CXX_CATCH);
+  RECORD(STMT_CXX_TRY);
+  RECORD(STMT_CXX_FOR_RANGE);
   RECORD(EXPR_CXX_OPERATOR_CALL);
   RECORD(EXPR_CXX_CONSTRUCT);
   RECORD(EXPR_CXX_STATIC_CAST);
@@ -765,11 +815,10 @@ static void AddStmtsExprs(llvm::BitstreamWriter &Stream,
   RECORD(EXPR_CXX_NULL_PTR_LITERAL);
   RECORD(EXPR_CXX_TYPEID_EXPR);
   RECORD(EXPR_CXX_TYPEID_TYPE);
-  RECORD(EXPR_CXX_UUIDOF_EXPR);
-  RECORD(EXPR_CXX_UUIDOF_TYPE);
   RECORD(EXPR_CXX_THIS);
   RECORD(EXPR_CXX_THROW);
   RECORD(EXPR_CXX_DEFAULT_ARG);
+  RECORD(EXPR_CXX_DEFAULT_INIT);
   RECORD(EXPR_CXX_BIND_TEMPORARY);
   RECORD(EXPR_CXX_SCALAR_VALUE_INIT);
   RECORD(EXPR_CXX_NEW);
@@ -781,12 +830,22 @@ static void AddStmtsExprs(llvm::BitstreamWriter &Stream,
   RECORD(EXPR_CXX_UNRESOLVED_CONSTRUCT);
   RECORD(EXPR_CXX_UNRESOLVED_MEMBER);
   RECORD(EXPR_CXX_UNRESOLVED_LOOKUP);
+  RECORD(EXPR_CXX_EXPRESSION_TRAIT);
   RECORD(EXPR_CXX_NOEXCEPT);
   RECORD(EXPR_OPAQUE_VALUE);
+  RECORD(EXPR_BINARY_CONDITIONAL_OPERATOR);
+  RECORD(EXPR_TYPE_TRAIT);
+  RECORD(EXPR_ARRAY_TYPE_TRAIT);
   RECORD(EXPR_PACK_EXPANSION);
   RECORD(EXPR_SIZEOF_PACK);
+  RECORD(EXPR_SUBST_NON_TYPE_TEMPLATE_PARM);
   RECORD(EXPR_SUBST_NON_TYPE_TEMPLATE_PARM_PACK);
+  RECORD(EXPR_FUNCTION_PARM_PACK);
+  RECORD(EXPR_MATERIALIZE_TEMPORARY);
   RECORD(EXPR_CUDA_KERNEL_CALL);
+  RECORD(EXPR_CXX_UUIDOF_EXPR);
+  RECORD(EXPR_CXX_UUIDOF_TYPE);
+  RECORD(EXPR_LAMBDA);
 #undef RECORD
 }
 
@@ -922,6 +981,7 @@ void ASTWriter::WriteBlockInfoBlock() {
   RECORD(TYPE_SUBST_TEMPLATE_TYPE_PARM_PACK);
   RECORD(TYPE_ATOMIC);
   RECORD(DECL_TYPEDEF);
+  RECORD(DECL_TYPEALIAS);
   RECORD(DECL_ENUM);
   RECORD(DECL_RECORD);
   RECORD(DECL_ENUM_CONSTANT);
@@ -2274,7 +2334,7 @@ void ASTWriter::WriteSubmodules(Module *WritingModule) {
   }
   
   // Enter the submodule description block.
-  Stream.EnterSubblock(SUBMODULE_BLOCK_ID, NUM_ALLOWED_ABBREVS_SIZE);
+  Stream.EnterSubblock(SUBMODULE_BLOCK_ID, /*bits for abbreviations*/4);
   
   // Write the abbreviations needed for the submodules block.
   using namespace llvm;
@@ -2614,12 +2674,14 @@ void ASTWriter::WriteType(QualType T) {
 
   // Emit the type's representation.
   ASTTypeWriter W(*this, Record);
+  W.AbbrevToUse = 0;
 
   if (T.hasLocalNonFastQualifiers()) {
     Qualifiers Qs = T.getLocalQualifiers();
     AddTypeRef(T.getLocalUnqualifiedType(), Record);
     Record.push_back(Qs.getAsOpaqueValue());
     W.Code = TYPE_EXT_QUAL;
+    W.AbbrevToUse = TypeExtQualAbbrev;
   } else {
     switch (T->getTypeClass()) {
       // For all of the concrete, non-dependent types, call the
@@ -2632,7 +2694,7 @@ void ASTWriter::WriteType(QualType T) {
   }
 
   // Emit the serialized record.
-  Stream.EmitRecord(W.Code, Record);
+  Stream.EmitRecord(W.Code, Record, W.AbbrevToUse);
 
   // Flush any expressions that were written as part of this type.
   FlushStmts();
@@ -3676,8 +3738,6 @@ uint64_t ASTWriter::WriteDeclContextVisibleBlock(ASTContext &Context,
   Record.push_back(BucketOffset);
   Stream.EmitRecordWithBlob(DeclContextVisibleLookupAbbrev, Record,
                             LookupTable.str());
-
-  Stream.EmitRecord(DECL_CONTEXT_VISIBLE, Record);
   ++NumVisibleDeclContexts;
   return Offset;
 }
@@ -3980,29 +4040,25 @@ void ASTWriter::SetSelectorOffset(Selector Sel, uint32_t Offset) {
 }
 
 ASTWriter::ASTWriter(llvm::BitstreamWriter &Stream)
-  : Stream(Stream), Context(nullptr), PP(nullptr), Chain(nullptr),
-    WritingModule(nullptr), WritingAST(false), DoneWritingDeclsAndTypes(false),
-    ASTHasCompilerErrors(false),
-    FirstDeclID(NUM_PREDEF_DECL_IDS), NextDeclID(FirstDeclID),
-    FirstTypeID(NUM_PREDEF_TYPE_IDS), NextTypeID(FirstTypeID),
-    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),
-    CollectedStmts(&StmtsToEmit),
-    NumStatements(0), NumMacros(0), NumLexicalDeclContexts(0),
-    NumVisibleDeclContexts(0),
-    NextCXXBaseSpecifiersID(1),
-    DeclParmVarAbbrev(0), DeclContextLexicalAbbrev(0),
-    DeclContextVisibleLookupAbbrev(0), UpdateVisibleAbbrev(0),
-    DeclRefExprAbbrev(0), CharacterLiteralAbbrev(0),
-    DeclRecordAbbrev(0), IntegerLiteralAbbrev(0),
-    DeclTypedefAbbrev(0),
-    DeclVarAbbrev(0), DeclFieldAbbrev(0),
-    DeclEnumAbbrev(0), DeclObjCIvarAbbrev(0)
-{
-}
+    : Stream(Stream), Context(nullptr), PP(nullptr), Chain(nullptr),
+      WritingModule(nullptr), WritingAST(false),
+      DoneWritingDeclsAndTypes(false), ASTHasCompilerErrors(false),
+      FirstDeclID(NUM_PREDEF_DECL_IDS), NextDeclID(FirstDeclID),
+      FirstTypeID(NUM_PREDEF_TYPE_IDS), NextTypeID(FirstTypeID),
+      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),
+      CollectedStmts(&StmtsToEmit), NumStatements(0), NumMacros(0),
+      NumLexicalDeclContexts(0), NumVisibleDeclContexts(0),
+      NextCXXBaseSpecifiersID(1), TypeExtQualAbbrev(0),
+      TypeFunctionProtoAbbrev(0), DeclParmVarAbbrev(0),
+      DeclContextLexicalAbbrev(0), DeclContextVisibleLookupAbbrev(0),
+      UpdateVisibleAbbrev(0), DeclRefExprAbbrev(0), CharacterLiteralAbbrev(0),
+      DeclRecordAbbrev(0), IntegerLiteralAbbrev(0), DeclTypedefAbbrev(0),
+      DeclVarAbbrev(0), DeclFieldAbbrev(0), DeclEnumAbbrev(0),
+      DeclObjCIvarAbbrev(0), DeclCXXMethodAbbrev(0) {}
 
 ASTWriter::~ASTWriter() {
   llvm::DeleteContainerSeconds(FileDeclIDs);
@@ -4374,8 +4430,9 @@ void ASTWriter::WriteASTCore(Sema &SemaRef,
 
   // Keep writing types, declarations, and declaration update records
   // until we've emitted all of them.
-  Stream.EnterSubblock(DECLTYPES_BLOCK_ID, NUM_ALLOWED_ABBREVS_SIZE);
-  WriteDeclsBlockAbbrevs();
+  Stream.EnterSubblock(DECLTYPES_BLOCK_ID, /*bits for abbreviations*/5);
+  WriteTypeAbbrevs();
+  WriteDeclAbbrevs();
   for (DeclsToRewriteTy::iterator I = DeclsToRewrite.begin(),
                                   E = DeclsToRewrite.end();
        I != E; ++I)

diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index 47ce747..1c69834 100644 (file)
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -224,12 +224,9 @@ void ASTDeclWriter::VisitTypedefDecl(TypedefDecl *D) {
   VisitTypedefNameDecl(D);
   if (!D->hasAttrs() &&
       !D->isImplicit() &&
-      !D->isUsed(false) &&
       D->getFirstDecl() == D->getMostRecentDecl() &&
       !D->isInvalidDecl() &&
-      !D->isReferenced() &&
       !D->isTopLevelDeclInObjCContainer() &&
-      D->getAccess() == AS_none &&
       !D->isModulePrivate() &&
       D->getDeclName().getNameKind() == DeclarationName::Identifier)
     AbbrevToUse = Writer.getDeclTypedefAbbrev();
@@ -349,7 +346,6 @@ void ASTDeclWriter::VisitDeclaratorDecl(DeclaratorDecl *D) {
 void ASTDeclWriter::VisitFunctionDecl(FunctionDecl *D) {
   VisitRedeclarable(D);
   VisitDeclaratorDecl(D);
-
   Writer.AddDeclarationNameLoc(D->DNLoc, D->getDeclName(), Record);
   Record.push_back(D->getIdentifierNamespace());
   
@@ -1027,6 +1023,17 @@ void ASTDeclWriter::VisitCXXMethodDecl(CXXMethodDecl *D) {
     // We only need to record overridden methods once for the canonical decl.
     Record.push_back(0);
   }
+
+  if (D->getFirstDecl() == D->getMostRecentDecl() &&
+      !D->isInvalidDecl() &&
+      !D->hasAttrs() &&
+      !D->isTopLevelDeclInObjCContainer() &&
+      D->getDeclName().getNameKind() == DeclarationName::Identifier &&
+      !D->hasExtInfo() &&
+      !D->hasInheritedPrototype() &&
+      D->hasWrittenPrototype())
+    AbbrevToUse = Writer.getDeclCXXMethodAbbrev();
+
   Code = serialization::DECL_CXX_METHOD;
 }
 
@@ -1449,7 +1456,7 @@ void ASTDeclWriter::VisitOMPThreadPrivateDecl(OMPThreadPrivateDecl *D) {
 // ASTWriter Implementation
 //===----------------------------------------------------------------------===//
 
-void ASTWriter::WriteDeclsBlockAbbrevs() {
+void ASTWriter::WriteDeclAbbrevs() {
   using namespace llvm;
 
   BitCodeAbbrev *Abv;
@@ -1676,10 +1683,10 @@ void ASTWriter::WriteDeclsBlockAbbrevs() {
   Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
   Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
   Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
-  Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
-  Abv->Add(BitCodeAbbrevOp(0));                       // isReferenced
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isUsed
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isReferenced
   Abv->Add(BitCodeAbbrevOp(0));                   // TopLevelDeclInObjCContainer
-  Abv->Add(BitCodeAbbrevOp(AS_none));                 // C++ AccessSpecifier
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2)); // C++ AccessSpecifier
   Abv->Add(BitCodeAbbrevOp(0));                       // ModulePrivate
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
   // NamedDecl
@@ -1738,6 +1745,63 @@ void ASTWriter::WriteDeclsBlockAbbrevs() {
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TypeLoc
   DeclVarAbbrev = Stream.EmitAbbrev(Abv);
 
+  // Abbreviation for DECL_CXX_METHOD
+  Abv = new BitCodeAbbrev();
+  Abv->Add(BitCodeAbbrevOp(serialization::DECL_CXX_METHOD));
+  // RedeclarableDecl
+  Abv->Add(BitCodeAbbrevOp(0));                         // CanonicalDecl
+  // Decl
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // DeclContext
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // LexicalDeclContext
+  Abv->Add(BitCodeAbbrevOp(0));                         // Invalid
+  Abv->Add(BitCodeAbbrevOp(0));                         // HasAttrs
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Implicit
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Used
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Referenced
+  Abv->Add(BitCodeAbbrevOp(0));                         // InObjCContainer
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2)); // Access
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // ModulePrivate
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // SubmoduleID
+  // NamedDecl
+  Abv->Add(BitCodeAbbrevOp(DeclarationName::Identifier)); // NameKind
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Identifier
+  // ValueDecl
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Type
+  // DeclaratorDecl
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // InnerLocStart
+  Abv->Add(BitCodeAbbrevOp(0));                         // HasExtInfo
+  // FunctionDecl
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 11)); // IDNS
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); // StorageClass
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Inline
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // InlineSpecified
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // VirtualAsWritten
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Pure
+  Abv->Add(BitCodeAbbrevOp(0));                         // HasInheritedProto
+  Abv->Add(BitCodeAbbrevOp(1));                         // HasWrittenProto
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // DeletedAsWritten
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Trivial
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Defaulted
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // ExplicitlyDefaulted
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // ImplicitReturnZero
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Constexpr
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // SkippedBody
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // LateParsed
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); // Linkage
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // LocEnd
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); // TemplateKind
+  // This Array slurps the rest of the record. Fortunately we want to encode
+  // (nearly) all the remaining (variable number of) fields in the same way.
+  //
+  // This is the function template information if any, then
+  //         NumParams and Params[] from FunctionDecl, and
+  //         NumOverriddenMethods, OverriddenMethods[] from CXXMethodDecl.
+  //
+  //  Add an AbbrevOp for 'size then elements' and use it here.
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
+  DeclCXXMethodAbbrev = Stream.EmitAbbrev(Abv);
+
   // Abbreviation for EXPR_DECL_REF
   Abv = new BitCodeAbbrev();
   Abv->Add(BitCodeAbbrevOp(serialization::EXPR_DECL_REF));