[AST] Store the results in OverloadExpr in a trailing array

[riccibruno]

Summary

Use the newly available space in the bit-fields of Stmt to pack
OverloadExpr, UnresolvedLookupExpr and UnresolvedMemberExpr.

Additionally store the results in the overload set in a trailing array.
This saves 1 pointer + 8 bytes per UnresolvedLookupExpr and UnresolvedMemberExpr.

[rjmccall]

LGTM.

include/clang/AST/ExprCXX.h

public:
   child_range children() {
     return child_range(child_iterator(), child_iterator());
   }
 };
 
 /// A reference to an overloaded function set, either an
 /// \c UnresolvedLookupExpr or an \c UnresolvedMemberExpr.
 class OverloadExpr : public Expr {
+  friend class ASTStmtReader;
+  friend class ASTStmtWriter;
+
   /// The common name of these declarations.
   DeclarationNameInfo NameInfo;
 
   /// The nested-name-specifier that qualifies the name, if any.
   NestedNameSpecifierLoc QualifierLoc;
 
-  /// The results.  These are undesugared, which is to say, they may
-  /// include UsingShadowDecls.  Access is relative to the naming
-  /// class.
-  // FIXME: Allocate this data after the OverloadExpr subclass.
-  DeclAccessPair *Results = nullptr;
-
-  unsigned NumResults = 0;
-
 protected:
-  /// Whether the name includes info for explicit template
-  /// keyword and arguments.
-  bool HasTemplateKWAndArgsInfo = false;
-
-  OverloadExpr(StmtClass K, const ASTContext &C,
+  OverloadExpr(StmtClass SC, const ASTContext &Context,
                NestedNameSpecifierLoc QualifierLoc,
                SourceLocation TemplateKWLoc,
                const DeclarationNameInfo &NameInfo,
                const TemplateArgumentListInfo *TemplateArgs,
                UnresolvedSetIterator Begin, UnresolvedSetIterator End,
-               bool KnownDependent,
-               bool KnownInstantiationDependent,
+               bool KnownDependent, bool KnownInstantiationDependent,
                bool KnownContainsUnexpandedParameterPack);
 
-  OverloadExpr(StmtClass K, EmptyShell Empty) : Expr(K, Empty) {}
+  OverloadExpr(StmtClass SC, EmptyShell Empty, unsigned NumResults,
+               bool HasTemplateKWAndArgsInfo);
 
-  /// Return the optional template keyword and arguments info.
-  ASTTemplateKWAndArgsInfo *
-  getTrailingASTTemplateKWAndArgsInfo(); // defined far below.
+  /// Return the results. Defined after UnresolvedMemberExpr.
+  inline DeclAccessPair *getTrailingResults();
+  const DeclAccessPair *getTrailingResults() const {
+    return const_cast<OverloadExpr *>(this)->getTrailingResults();
+  }
 
   /// Return the optional template keyword and arguments info.
+  /// Defined after UnresolvedMemberExpr.
+  inline ASTTemplateKWAndArgsInfo *getTrailingASTTemplateKWAndArgsInfo();
   const ASTTemplateKWAndArgsInfo *getTrailingASTTemplateKWAndArgsInfo() const {
     return const_cast<OverloadExpr *>(this)
         ->getTrailingASTTemplateKWAndArgsInfo();
   }
 
-  /// Return the optional template arguments.
-  TemplateArgumentLoc *getTrailingTemplateArgumentLoc(); // defined far below
+  /// Return the optional template arguments. Defined after
+  /// UnresolvedMemberExpr.
+  inline TemplateArgumentLoc *getTrailingTemplateArgumentLoc();
+  const TemplateArgumentLoc *getTrailingTemplateArgumentLoc() const {
+    return const_cast<OverloadExpr *>(this)->getTrailingTemplateArgumentLoc();
+  }
 
-  void initializeResults(const ASTContext &C,
-                         UnresolvedSetIterator Begin,
-                         UnresolvedSetIterator End);
+  bool hasTemplateKWAndArgsInfo() const {
+    return OverloadExprBits.HasTemplateKWAndArgsInfo;
+  }
 
 public:
-  friend class ASTStmtReader;
-  friend class ASTStmtWriter;
-
   struct FindResult {
     OverloadExpr *Expression;
     bool IsAddressOfOperand;
     bool HasFormOfMemberPointer;
   };
 
   /// Finds the overloaded expression in the given expression \p E of
   /// OverloadTy.
if (isa<UnaryOperator>(E)) {
       Result.IsAddressOfOperand = false;
       Result.Expression = cast<OverloadExpr>(E);
     }
 
     return Result;
   }
 
   /// Gets the naming class of this lookup, if any.
-  CXXRecordDecl *getNamingClass() const;
+  /// Defined after UnresolvedMemberExpr.
+  inline CXXRecordDecl *getNamingClass();
+  const CXXRecordDecl *getNamingClass() const {
+    return const_cast<OverloadExpr *>(this)->getNamingClass();
+  }
 
   using decls_iterator = UnresolvedSetImpl::iterator;
 
-  decls_iterator decls_begin() const { return UnresolvedSetIterator(Results); }
+  decls_iterator decls_begin() const {
+    return UnresolvedSetIterator(getTrailingResults());
+  }
   decls_iterator decls_end() const {
-    return UnresolvedSetIterator(Results + NumResults);
+    return UnresolvedSetIterator(getTrailingResults() + getNumDecls());
   }
   llvm::iterator_range<decls_iterator> decls() const {
     return llvm::make_range(decls_begin(), decls_end());
   }
 
   /// Gets the number of declarations in the unresolved set.
-  unsigned getNumDecls() const { return NumResults; }
+  unsigned getNumDecls() const { return OverloadExprBits.NumResults; }
 
   /// Gets the full name info.
   const DeclarationNameInfo &getNameInfo() const { return NameInfo; }
 
   /// Gets the name looked up.
   DeclarationName getName() const { return NameInfo.getName(); }
 
   /// Gets the location of the name.
   SourceLocation getNameLoc() const { return NameInfo.getLoc(); }
 
   /// Fetches the nested-name qualifier, if one was given.
   NestedNameSpecifier *getQualifier() const {
     return QualifierLoc.getNestedNameSpecifier();
   }
 
   /// Fetches the nested-name qualifier with source-location
   /// information, if one was given.
   NestedNameSpecifierLoc getQualifierLoc() const { return QualifierLoc; }
 
   /// Retrieve the location of the template keyword preceding
   /// this name, if any.
   SourceLocation getTemplateKeywordLoc() const {
-    if (!HasTemplateKWAndArgsInfo) return SourceLocation();
+    if (!hasTemplateKWAndArgsInfo())
+      return SourceLocation();
     return getTrailingASTTemplateKWAndArgsInfo()->TemplateKWLoc;
   }
 
   /// Retrieve the location of the left angle bracket starting the
   /// explicit template argument list following the name, if any.
   SourceLocation getLAngleLoc() const {
-    if (!HasTemplateKWAndArgsInfo) return SourceLocation();
+    if (!hasTemplateKWAndArgsInfo())
+      return SourceLocation();
     return getTrailingASTTemplateKWAndArgsInfo()->LAngleLoc;
   }
 
   /// Retrieve the location of the right angle bracket ending the
   /// explicit template argument list following the name, if any.
   SourceLocation getRAngleLoc() const {
-    if (!HasTemplateKWAndArgsInfo) return SourceLocation();
+    if (!hasTemplateKWAndArgsInfo())
+      return SourceLocation();
     return getTrailingASTTemplateKWAndArgsInfo()->RAngleLoc;
   }
 
   /// Determines whether the name was preceded by the template keyword.
   bool hasTemplateKeyword() const { return getTemplateKeywordLoc().isValid(); }
 
   /// Determines whether this expression had explicit template arguments.
   bool hasExplicitTemplateArgs() const { return getLAngleLoc().isValid(); }

 ///   * the name might resolve to an overloaded function;
 /// and eventually:
 ///   * the lookup might have included a function template.
 ///
 /// These never include UnresolvedUsingValueDecls, which are always class
 /// members and therefore appear only in UnresolvedMemberLookupExprs.
 class UnresolvedLookupExpr final
     : public OverloadExpr,
-      private llvm::TrailingObjects<
-          UnresolvedLookupExpr, ASTTemplateKWAndArgsInfo, TemplateArgumentLoc> {
+      private llvm::TrailingObjects<UnresolvedLookupExpr, DeclAccessPair,
+                                    ASTTemplateKWAndArgsInfo,
+                                    TemplateArgumentLoc> {
   friend class ASTStmtReader;
   friend class OverloadExpr;
   friend TrailingObjects;
 
-  /// True if these lookup results should be extended by
-  /// argument-dependent lookup if this is the operand of a function
-  /// call.
-  bool RequiresADL = false;
-
-  /// True if these lookup results are overloaded.  This is pretty
-  /// trivially rederivable if we urgently need to kill this field.
-  bool Overloaded = false;
-
   /// The naming class (C++ [class.access.base]p5) of the lookup, if
   /// any.  This can generally be recalculated from the context chain,
-  /// but that can be fairly expensive for unqualified lookups.  If we
-  /// want to improve memory use here, this could go in a union
-  /// against the qualified-lookup bits.
-  CXXRecordDecl *NamingClass = nullptr;
+  /// but that can be fairly expensive for unqualified lookups.
+  CXXRecordDecl *NamingClass;
+
+  // UnresolvedLookupExpr is followed by several trailing objects.
+  // They are in order:
+  //
+  // * An array of getNumResults() DeclAccessPair for the results. These are
+  //   undesugared, which is to say, they may include UsingShadowDecls.
+  //   Access is relative to the naming class.
+  //
+  // * An optional ASTTemplateKWAndArgsInfo for the explicitly specified
+  //   template keyword and arguments. Present if and only if
+  //   hasTemplateKWAndArgsInfo().
+  //
+  // * An array of getNumTemplateArgs() TemplateArgumentLoc containing
+  //   location information for the explicitly specified template arguments.
 
-  UnresolvedLookupExpr(const ASTContext &C,
-                       CXXRecordDecl *NamingClass,
+  UnresolvedLookupExpr(const ASTContext &Context, CXXRecordDecl *NamingClass,
                        NestedNameSpecifierLoc QualifierLoc,
                        SourceLocation TemplateKWLoc,
-                       const DeclarationNameInfo &NameInfo,
-                       bool RequiresADL, bool Overloaded,
+                       const DeclarationNameInfo &NameInfo, bool RequiresADL,
+                       bool Overloaded,
                        const TemplateArgumentListInfo *TemplateArgs,
-                       UnresolvedSetIterator Begin, UnresolvedSetIterator End)
-      : OverloadExpr(UnresolvedLookupExprClass, C, QualifierLoc, TemplateKWLoc,
-                     NameInfo, TemplateArgs, Begin, End, false, false, false),
-        RequiresADL(RequiresADL),
-        Overloaded(Overloaded), NamingClass(NamingClass) {}
+                       UnresolvedSetIterator Begin, UnresolvedSetIterator End);
 
-  UnresolvedLookupExpr(EmptyShell Empty)
-      : OverloadExpr(UnresolvedLookupExprClass, Empty) {}
+  UnresolvedLookupExpr(EmptyShell Empty, unsigned NumResults,
+                       bool HasTemplateKWAndArgsInfo);
 
-  size_t numTrailingObjects(OverloadToken<ASTTemplateKWAndArgsInfo>) const {
-    return HasTemplateKWAndArgsInfo ? 1 : 0;
+  unsigned numTrailingObjects(OverloadToken<DeclAccessPair>) const {
+    return getNumDecls();
   }
 
-public:
-  static UnresolvedLookupExpr *Create(const ASTContext &C,
-                                      CXXRecordDecl *NamingClass,
-                                      NestedNameSpecifierLoc QualifierLoc,
-                                      const DeclarationNameInfo &NameInfo,
-                                      bool ADL, bool Overloaded,
-                                      UnresolvedSetIterator Begin,
-                                      UnresolvedSetIterator End) {
-    return new(C) UnresolvedLookupExpr(C, NamingClass, QualifierLoc,
-                                       SourceLocation(), NameInfo,
-                                       ADL, Overloaded, nullptr, Begin, End);
+  unsigned numTrailingObjects(OverloadToken<ASTTemplateKWAndArgsInfo>) const {
+    return hasTemplateKWAndArgsInfo();
   }
 
-  static UnresolvedLookupExpr *Create(const ASTContext &C,
-                                      CXXRecordDecl *NamingClass,
-                                      NestedNameSpecifierLoc QualifierLoc,
-                                      SourceLocation TemplateKWLoc,
-                                      const DeclarationNameInfo &NameInfo,
-                                      bool ADL,
-                                      const TemplateArgumentListInfo *Args,
-                                      UnresolvedSetIterator Begin,
-                                      UnresolvedSetIterator End);
+public:
+  static UnresolvedLookupExpr *
+  Create(const ASTContext &Context, CXXRecordDecl *NamingClass,
+         const DeclarationNameInfo &NameInfo, bool RequiresADL, bool Overloaded,
+         UnresolvedSetIterator Begin, UnresolvedSetIterator End);
+
+  static UnresolvedLookupExpr *
+  Create(const ASTContext &Context, CXXRecordDecl *NamingClass,
+         NestedNameSpecifierLoc QualifierLoc, SourceLocation TemplateKWLoc,
+         const DeclarationNameInfo &NameInfo, bool RequiresADL,
+         const TemplateArgumentListInfo *Args, UnresolvedSetIterator Begin,
 
-  static UnresolvedLookupExpr *CreateEmpty(const ASTContext &C,
+  static UnresolvedLookupExpr *CreateEmpty(const ASTContext &Context,
+                                           unsigned NumResults,
                                            bool HasTemplateKWAndArgsInfo,
                                            unsigned NumTemplateArgs);
 
   /// True if this declaration should be extended by
   /// argument-dependent lookup.
-  bool requiresADL() const { return RequiresADL; }
+  bool requiresADL() const { return UnresolvedLookupExprBits.RequiresADL; }
 
   /// True if this lookup is overloaded.
-  bool isOverloaded() const { return Overloaded; }
+  bool isOverloaded() const { return UnresolvedLookupExprBits.Overloaded; }
 
   /// Gets the 'naming class' (in the sense of C++0x
   /// [class.access.base]p5) of the lookup.  This is the scope
   /// that was looked in to find these results.
-  CXXRecordDecl *getNamingClass() const { return NamingClass; }
+  CXXRecordDecl *getNamingClass() { return NamingClass; }
+  const CXXRecordDecl *getNamingClass() const { return NamingClass; }
 
   SourceLocation getBeginLoc() const LLVM_READONLY {
     if (NestedNameSpecifierLoc l = getQualifierLoc())
       return l.getBeginLoc();
     return getNameInfo().getBeginLoc();
   }
 
   SourceLocation getEndLoc() const LLVM_READONLY {

 ///    };
 /// \endcode
 ///
 /// In the final AST, an explicit access always becomes a MemberExpr.
 /// An implicit access may become either a MemberExpr or a
 /// DeclRefExpr, depending on whether the member is static.
 class UnresolvedMemberExpr final
     : public OverloadExpr,
-      private llvm::TrailingObjects<
-          UnresolvedMemberExpr, ASTTemplateKWAndArgsInfo, TemplateArgumentLoc> {
+      private llvm::TrailingObjects<UnresolvedMemberExpr, DeclAccessPair,
+                                    ASTTemplateKWAndArgsInfo,
+                                    TemplateArgumentLoc> {
   friend class ASTStmtReader;
   friend class OverloadExpr;
   friend TrailingObjects;
 
-  /// Whether this member expression used the '->' operator or
-  /// the '.' operator.
-  bool IsArrow : 1;
-
-  /// Whether the lookup results contain an unresolved using
-  /// declaration.
-  bool HasUnresolvedUsing : 1;
-
   /// The expression for the base pointer or class reference,
   /// e.g., the \c x in x.f.
   ///
   /// This can be null if this is an 'unbased' member expression.
-  Stmt *Base = nullptr;
+  Stmt *Base;
 
   /// The type of the base expression; never null.
   QualType BaseType;
 
   /// The location of the '->' or '.' operator.
   SourceLocation OperatorLoc;
 
-  UnresolvedMemberExpr(const ASTContext &C, bool HasUnresolvedUsing,
+  // UnresolvedMemberExpr is followed by several trailing objects.
+  // They are in order:
+  //
+  // * An array of getNumResults() DeclAccessPair for the results. These are
+  //   undesugared, which is to say, they may include UsingShadowDecls.
+  //   Access is relative to the naming class.
+  //
+  // * An optional ASTTemplateKWAndArgsInfo for the explicitly specified
+  //   template keyword and arguments. Present if and only if
+  //   hasTemplateKWAndArgsInfo().
+  //
+  // * An array of getNumTemplateArgs() TemplateArgumentLoc containing
+  //   location information for the explicitly specified template arguments.
+
+  UnresolvedMemberExpr(const ASTContext &Context, bool HasUnresolvedUsing,
                        Expr *Base, QualType BaseType, bool IsArrow,
                        SourceLocation OperatorLoc,
                        NestedNameSpecifierLoc QualifierLoc,
                        SourceLocation TemplateKWLoc,
                        const DeclarationNameInfo &MemberNameInfo,
                        const TemplateArgumentListInfo *TemplateArgs,
                        UnresolvedSetIterator Begin, UnresolvedSetIterator End);
 
-  UnresolvedMemberExpr(EmptyShell Empty)
-      : OverloadExpr(UnresolvedMemberExprClass, Empty), IsArrow(false),
-        HasUnresolvedUsing(false) {}
+  UnresolvedMemberExpr(EmptyShell Empty, unsigned NumResults,
+                       bool HasTemplateKWAndArgsInfo);
 
-  size_t numTrailingObjects(OverloadToken<ASTTemplateKWAndArgsInfo>) const {
-    return HasTemplateKWAndArgsInfo ? 1 : 0;
+  unsigned numTrailingObjects(OverloadToken<DeclAccessPair>) const {
+    return getNumDecls();
+  }
+
+  unsigned numTrailingObjects(OverloadToken<ASTTemplateKWAndArgsInfo>) const {
+    return hasTemplateKWAndArgsInfo();
   }
 
 public:
   static UnresolvedMemberExpr *
-  Create(const ASTContext &C, bool HasUnresolvedUsing,
-         Expr *Base, QualType BaseType, bool IsArrow,
-         SourceLocation OperatorLoc,
-         NestedNameSpecifierLoc QualifierLoc,
-         SourceLocation TemplateKWLoc,
+  Create(const ASTContext &Context, bool HasUnresolvedUsing, Expr *Base,
+         QualType BaseType, bool IsArrow, SourceLocation OperatorLoc,
+         NestedNameSpecifierLoc QualifierLoc, SourceLocation TemplateKWLoc,
          const DeclarationNameInfo &MemberNameInfo,
          const TemplateArgumentListInfo *TemplateArgs,
          UnresolvedSetIterator Begin, UnresolvedSetIterator End);
 
-  static UnresolvedMemberExpr *
-  CreateEmpty(const ASTContext &C, bool HasTemplateKWAndArgsInfo,
+  static UnresolvedMemberExpr *CreateEmpty(const ASTContext &Context,
+                                           unsigned NumResults,
+                                           bool HasTemplateKWAndArgsInfo,
                                            unsigned NumTemplateArgs);
 
   /// True if this is an implicit access, i.e., one in which the
   /// member being accessed was not written in the source.
   ///
   /// The source location of the operator is invalid in this case.
   bool isImplicitAccess() const;
 
   /// Retrieve the base object of this member expressions,
   /// e.g., the \c x in \c x.m.
   Expr *getBase() {
     assert(!isImplicitAccess());
     return cast<Expr>(Base);
   }
   const Expr *getBase() const {
     assert(!isImplicitAccess());
     return cast<Expr>(Base);
   }
 
   QualType getBaseType() const { return BaseType; }
 
   /// Determine whether the lookup results contain an unresolved using
   /// declaration.
-  bool hasUnresolvedUsing() const { return HasUnresolvedUsing; }
+  bool hasUnresolvedUsing() const {
+    return UnresolvedMemberExprBits.HasUnresolvedUsing;
+  }
 
   /// Determine whether this member expression used the '->'
   /// operator; otherwise, it used the '.' operator.
-  bool isArrow() const { return IsArrow; }
+  bool isArrow() const { return UnresolvedMemberExprBits.IsArrow; }
 
   /// Retrieve the location of the '->' or '.' operator.
   SourceLocation getOperatorLoc() const { return OperatorLoc; }
 
   /// Retrieve the naming class of this lookup.
-  CXXRecordDecl *getNamingClass() const;
+  CXXRecordDecl *getNamingClass();
+  const CXXRecordDecl *getNamingClass() const {
+    return const_cast<UnresolvedMemberExpr *>(this)->getNamingClass();
+  }
 
   /// Retrieve the full name info for the member that this expression
   /// refers to.
   const DeclarationNameInfo &getMemberNameInfo() const { return getNameInfo(); }
 
-  /// Retrieve the name of the member that this expression
-  /// refers to.
+  /// Retrieve the name of the member that this expression refers to.
   DeclarationName getMemberName() const { return getName(); }
 
-  // Retrieve the location of the name of the member that this
-  // expression refers to.
+  /// Retrieve the location of the name of the member that this
+  /// expression refers to.
   SourceLocation getMemberLoc() const { return getNameLoc(); }
 
-  // Return the preferred location (the member name) for the arrow when
-  // diagnosing a problem with this expression.
+  /// Return the preferred location (the member name) for the arrow when
+  /// diagnosing a problem with this expression.
   SourceLocation getExprLoc() const LLVM_READONLY { return getMemberLoc(); }
 
   SourceLocation getBeginLoc() const LLVM_READONLY {
     if (!isImplicitAccess())
       return Base->getBeginLoc();
     if (NestedNameSpecifierLoc l = getQualifierLoc())
       return l.getBeginLoc();
     return getMemberNameInfo().getBeginLoc();
public:
   // Iterators
   child_range children() {
     if (isImplicitAccess())
       return child_range(child_iterator(), child_iterator());
     return child_range(&Base, &Base + 1);
   }
 };
 
-inline ASTTemplateKWAndArgsInfo *
-OverloadExpr::getTrailingASTTemplateKWAndArgsInfo() {
-  if (!HasTemplateKWAndArgsInfo)
+DeclAccessPair *OverloadExpr::getTrailingResults() {
+  if (auto *ULE = dyn_cast<UnresolvedLookupExpr>(this))
+    return ULE->getTrailingObjects<DeclAccessPair>();
+  return cast<UnresolvedMemberExpr>(this)->getTrailingObjects<DeclAccessPair>();
+}
+
+ASTTemplateKWAndArgsInfo *OverloadExpr::getTrailingASTTemplateKWAndArgsInfo() {
+  if (!hasTemplateKWAndArgsInfo())
     return nullptr;
 
-  if (isa<UnresolvedLookupExpr>(this))
-    return cast<UnresolvedLookupExpr>(this)
-        ->getTrailingObjects<ASTTemplateKWAndArgsInfo>();
-  else
-    return cast<UnresolvedMemberExpr>(this)
-        ->getTrailingObjects<ASTTemplateKWAndArgsInfo>();
+  if (auto *ULE = dyn_cast<UnresolvedLookupExpr>(this))
+    return ULE->getTrailingObjects<ASTTemplateKWAndArgsInfo>();
 }
 
-inline TemplateArgumentLoc *OverloadExpr::getTrailingTemplateArgumentLoc() {
-  if (isa<UnresolvedLookupExpr>(this))
-    return cast<UnresolvedLookupExpr>(this)
-        ->getTrailingObjects<TemplateArgumentLoc>();
-  else
-    return cast<UnresolvedMemberExpr>(this)
-        ->getTrailingObjects<TemplateArgumentLoc>();
+TemplateArgumentLoc *OverloadExpr::getTrailingTemplateArgumentLoc() {
+  if (auto *ULE = dyn_cast<UnresolvedLookupExpr>(this))
+    return ULE->getTrailingObjects<TemplateArgumentLoc>();
 }
 
+CXXRecordDecl *OverloadExpr::getNamingClass() {
+  if (auto *ULE = dyn_cast<UnresolvedLookupExpr>(this))
+    return ULE->getNamingClass();
+  return cast<UnresolvedMemberExpr>(this)->getNamingClass();
+}
+
 /// Represents a C++11 noexcept expression (C++ [expr.unary.noexcept]).
 ///
 /// The noexcept expression tests whether a given expression might throw. Its
 /// result is a boolean constant.
 class CXXNoexceptExpr : public Expr {
   friend class ASTStmtReader;
 
   Stmt *Operand;

include/clang/AST/Stmt.h

class CXXDependentScopeMemberExprBitfields {
     /// See getFirstQualifierFoundInScope() and the comment listing
     /// the trailing objects.
     unsigned HasFirstQualifierFoundInScope : 1;
 
     /// The location of the '->' or '.' operator.
     SourceLocation OperatorLoc;
   };
 
+  class OverloadExprBitfields {
+    friend class ASTStmtReader;
+    friend class OverloadExpr;
+
+    unsigned : NumExprBits;
+
+    /// Whether the name includes info for explicit template
+    /// keyword and arguments.
+    unsigned HasTemplateKWAndArgsInfo : 1;
+
+    /// Padding used by the derived classes to store various bits. If you
+    /// need to add some data here, shrink this padding and add your data
+    /// above. NumOverloadExprBits also needs to be updated.
+    unsigned : 32 - NumExprBits - 1;
+
+    /// The number of results.
+    unsigned NumResults;
+  };
+  enum { NumOverloadExprBits = NumExprBits + 1 };
+
+  class UnresolvedLookupExprBitfields {
+    friend class ASTStmtReader;
+    friend class UnresolvedLookupExpr;
+
+    unsigned : NumOverloadExprBits;
+
+    /// True if these lookup results should be extended by
+    /// argument-dependent lookup if this is the operand of a function call.
+    unsigned RequiresADL : 1;
+
+    /// True if these lookup results are overloaded.  This is pretty trivially
+    /// rederivable if we urgently need to kill this field.
+    unsigned Overloaded : 1;
+  };
+  static_assert(sizeof(UnresolvedLookupExprBitfields) <= 4,
+                "UnresolvedLookupExprBitfields must be <= than 4 bytes to"
+                "avoid trashing OverloadExprBitfields::NumResults!");
+
+  class UnresolvedMemberExprBitfields {
+    friend class ASTStmtReader;
+    friend class UnresolvedMemberExpr;
+
+    unsigned : NumOverloadExprBits;
+
+    /// Whether this member expression used the '->' operator or
+    /// the '.' operator.
+    unsigned IsArrow : 1;
+
+    /// Whether the lookup results contain an unresolved using declaration.
+    unsigned HasUnresolvedUsing : 1;
+  };
+  static_assert(sizeof(UnresolvedMemberExprBitfields) <= 4,
+                "UnresolvedMemberExprBitfields must be <= than 4 bytes to"
+                "avoid trashing OverloadExprBitfields::NumResults!");
+
   class CXXNoexceptExprBitfields {
     friend class ASTStmtReader;
     friend class CXXNoexceptExpr;
 
     unsigned : NumExprBits;
 
     unsigned Value : 1;
   };
union {
     CXXNewExprBitfields CXXNewExprBits;
     CXXDeleteExprBitfields CXXDeleteExprBits;
     TypeTraitExprBitfields TypeTraitExprBits;
     DependentScopeDeclRefExprBitfields DependentScopeDeclRefExprBits;
     CXXConstructExprBitfields CXXConstructExprBits;
     ExprWithCleanupsBitfields ExprWithCleanupsBits;
     CXXUnresolvedConstructExprBitfields CXXUnresolvedConstructExprBits;
     CXXDependentScopeMemberExprBitfields CXXDependentScopeMemberExprBits;
+    OverloadExprBitfields OverloadExprBits;
+    UnresolvedLookupExprBitfields UnresolvedLookupExprBits;
+    UnresolvedMemberExprBitfields UnresolvedMemberExprBits;
     CXXNoexceptExprBitfields CXXNoexceptExprBits;
     SubstNonTypeTemplateParmExprBitfields SubstNonTypeTemplateParmExprBits;
 
     // C++ Coroutines TS expressions
     CoawaitExprBitfields CoawaitBits;
 
     // Obj-C Expressions
     ObjCIndirectCopyRestoreExprBitfields ObjCIndirectCopyRestoreExprBits;

lib/AST/ExprCXX.cpp

 SourceLocation CXXPseudoDestructorExpr::getEndLoc() const {
   SourceLocation End = DestroyedType.getLocation();
   if (TypeSourceInfo *TInfo = DestroyedType.getTypeSourceInfo())
     End = TInfo->getTypeLoc().getLocalSourceRange().getEnd();
   return End;
 }
 
 // UnresolvedLookupExpr
-UnresolvedLookupExpr *
-UnresolvedLookupExpr::Create(const ASTContext &C,
-                             CXXRecordDecl *NamingClass,
-                             NestedNameSpecifierLoc QualifierLoc,
-                             SourceLocation TemplateKWLoc,
-                             const DeclarationNameInfo &NameInfo,
-                             bool ADL,
-                             const TemplateArgumentListInfo *Args,
-                             UnresolvedSetIterator Begin,
-                             UnresolvedSetIterator End) {
-  assert(Args || TemplateKWLoc.isValid());
-  unsigned num_args = Args ? Args->size() : 0;
+UnresolvedLookupExpr::UnresolvedLookupExpr(
+    const ASTContext &Context, CXXRecordDecl *NamingClass,
+    NestedNameSpecifierLoc QualifierLoc, SourceLocation TemplateKWLoc,
+    const DeclarationNameInfo &NameInfo, bool RequiresADL, bool Overloaded,
+    const TemplateArgumentListInfo *TemplateArgs, UnresolvedSetIterator Begin,
+    UnresolvedSetIterator End)
+    : OverloadExpr(UnresolvedLookupExprClass, Context, QualifierLoc,
+                   TemplateKWLoc, NameInfo, TemplateArgs, Begin, End, false,
+                   false, false),
+      NamingClass(NamingClass) {
+  UnresolvedLookupExprBits.RequiresADL = RequiresADL;
+  UnresolvedLookupExprBits.Overloaded = Overloaded;
+}
+
+UnresolvedLookupExpr::UnresolvedLookupExpr(EmptyShell Empty,
+                                           unsigned NumResults,
+                                           bool HasTemplateKWAndArgsInfo)
+    : OverloadExpr(UnresolvedLookupExprClass, Empty, NumResults,
+                   HasTemplateKWAndArgsInfo) {}
+
+UnresolvedLookupExpr *UnresolvedLookupExpr::Create(
+    const ASTContext &Context, CXXRecordDecl *NamingClass,
+    NestedNameSpecifierLoc QualifierLoc, const DeclarationNameInfo &NameInfo,
+    bool RequiresADL, bool Overloaded, UnresolvedSetIterator Begin,
+  unsigned NumResults = End - Begin;
+  unsigned Size = totalSizeToAlloc<DeclAccessPair, ASTTemplateKWAndArgsInfo,
+                                   TemplateArgumentLoc>(NumResults, 0, 0);
+  void *Mem = Context.Allocate(Size, alignof(UnresolvedLookupExpr));
+  return new (Mem) UnresolvedLookupExpr(Context, NamingClass, QualifierLoc,
+                                        SourceLocation(), NameInfo, RequiresADL,
+                                        Overloaded, nullptr, Begin, End);
+}
 
-  std::size_t Size =
-      totalSizeToAlloc<ASTTemplateKWAndArgsInfo, TemplateArgumentLoc>(1,
-                                                                      num_args);
-  void *Mem = C.Allocate(Size, alignof(UnresolvedLookupExpr));
-  return new (Mem) UnresolvedLookupExpr(C, NamingClass, QualifierLoc,
-                                        TemplateKWLoc, NameInfo,
-                                        ADL, /*Overload*/ true, Args,
-                                        Begin, End);
+UnresolvedLookupExpr *UnresolvedLookupExpr::Create(
+    const ASTContext &Context, CXXRecordDecl *NamingClass,
+    NestedNameSpecifierLoc QualifierLoc, SourceLocation TemplateKWLoc,
+    const DeclarationNameInfo &NameInfo, bool RequiresADL,
+    const TemplateArgumentListInfo *Args, UnresolvedSetIterator Begin,
+    UnresolvedSetIterator End) {
+  assert(Args || TemplateKWLoc.isValid());
+  unsigned NumResults = End - Begin;
+  unsigned NumTemplateArgs = Args ? Args->size() : 0;
+  unsigned Size =
+      totalSizeToAlloc<DeclAccessPair, ASTTemplateKWAndArgsInfo,
+                       TemplateArgumentLoc>(NumResults, 1, NumTemplateArgs);
+  void *Mem = Context.Allocate(Size, alignof(UnresolvedLookupExpr));
+  return new (Mem) UnresolvedLookupExpr(Context, NamingClass, QualifierLoc,
+                                        TemplateKWLoc, NameInfo, RequiresADL,
+                                        /*Overloaded*/ true, Args, Begin, End);
 }
 
-UnresolvedLookupExpr *
-UnresolvedLookupExpr::CreateEmpty(const ASTContext &C,
-                                  bool HasTemplateKWAndArgsInfo,
-                                  unsigned NumTemplateArgs) {
+UnresolvedLookupExpr *UnresolvedLookupExpr::CreateEmpty(
+    const ASTContext &Context, unsigned NumResults,
+    bool HasTemplateKWAndArgsInfo, unsigned NumTemplateArgs) {
   assert(NumTemplateArgs == 0 || HasTemplateKWAndArgsInfo);
-  std::size_t Size =
-      totalSizeToAlloc<ASTTemplateKWAndArgsInfo, TemplateArgumentLoc>(
-          HasTemplateKWAndArgsInfo, NumTemplateArgs);
-  void *Mem = C.Allocate(Size, alignof(UnresolvedLookupExpr));
-  auto *E = new (Mem) UnresolvedLookupExpr(EmptyShell());
-  E->HasTemplateKWAndArgsInfo = HasTemplateKWAndArgsInfo;
-  return E;
+  unsigned Size = totalSizeToAlloc<DeclAccessPair, ASTTemplateKWAndArgsInfo,
+                                   TemplateArgumentLoc>(
+      NumResults, HasTemplateKWAndArgsInfo, NumTemplateArgs);
+  void *Mem = Context.Allocate(Size, alignof(UnresolvedLookupExpr));
+  return new (Mem)
+      UnresolvedLookupExpr(EmptyShell(), NumResults, HasTemplateKWAndArgsInfo);
 }
 
-OverloadExpr::OverloadExpr(StmtClass K, const ASTContext &C,
+OverloadExpr::OverloadExpr(StmtClass SC, const ASTContext &Context,
                            NestedNameSpecifierLoc QualifierLoc,
                            SourceLocation TemplateKWLoc,
                            const DeclarationNameInfo &NameInfo,
                            const TemplateArgumentListInfo *TemplateArgs,
                            UnresolvedSetIterator Begin,
-                           UnresolvedSetIterator End,
-                           bool KnownDependent,
+                           UnresolvedSetIterator End, bool KnownDependent,
                            bool KnownInstantiationDependent,
                            bool KnownContainsUnexpandedParameterPack)
-    : Expr(K, C.OverloadTy, VK_LValue, OK_Ordinary, KnownDependent,
-           KnownDependent,
-           (KnownInstantiationDependent ||
-            NameInfo.isInstantiationDependent() ||
-            (QualifierLoc &&
+    : Expr(
+          SC, Context.OverloadTy, VK_LValue, OK_Ordinary, KnownDependent,
+          (KnownInstantiationDependent || NameInfo.isInstantiationDependent() ||
             QualifierLoc.getNestedNameSpecifier()->isInstantiationDependent())),
-           (KnownContainsUnexpandedParameterPack ||
-            NameInfo.containsUnexpandedParameterPack() ||
-            (QualifierLoc &&
-             QualifierLoc.getNestedNameSpecifier()
-                                        ->containsUnexpandedParameterPack()))),
-      NameInfo(NameInfo), QualifierLoc(QualifierLoc), NumResults(End - Begin),
-      HasTemplateKWAndArgsInfo(TemplateArgs != nullptr ||
-                               TemplateKWLoc.isValid()) {
-  NumResults = End - Begin;
+           (QualifierLoc && QualifierLoc.getNestedNameSpecifier()
+      NameInfo(NameInfo), QualifierLoc(QualifierLoc) {
+  unsigned NumResults = End - Begin;
+  OverloadExprBits.NumResults = NumResults;
+  OverloadExprBits.HasTemplateKWAndArgsInfo =
+      (TemplateArgs != nullptr ) || TemplateKWLoc.isValid();
+
   if (NumResults) {
     // Determine whether this expression is type-dependent.
     for (UnresolvedSetImpl::const_iterator I = Begin; I != End; ++I) {
       if ((*I)->getDeclContext()->isDependentContext() ||
           isa<UnresolvedUsingValueDecl>(*I)) {
         ExprBits.TypeDependent = true;
         ExprBits.ValueDependent = true;
         ExprBits.InstantiationDependent = true;
       }
     }
 
-    Results = static_cast<DeclAccessPair *>(C.Allocate(
-        sizeof(DeclAccessPair) * NumResults, alignof(DeclAccessPair)));
+    // Copy the results to the trailing array past UnresolvedLookupExpr
+    // or UnresolvedMemberExpr.
+    DeclAccessPair *Results = getTrailingResults();
     memcpy(Results, Begin.I, NumResults * sizeof(DeclAccessPair));
   }
 
   // If we have explicit template arguments, check for dependent
   // template arguments and whether they contain any unexpanded pack
   // expansions.
   if (TemplateArgs) {
     bool Dependent = false;
if (InstantiationDependent)
       ExprBits.InstantiationDependent = true;
     if (ContainsUnexpandedParameterPack)
       ExprBits.ContainsUnexpandedParameterPack = true;
   } else if (TemplateKWLoc.isValid()) {
     getTrailingASTTemplateKWAndArgsInfo()->initializeFrom(TemplateKWLoc);
   }
 
   if (isTypeDependent())
-    setType(C.DependentTy);
-}
-
-void OverloadExpr::initializeResults(const ASTContext &C,
-                                     UnresolvedSetIterator Begin,
-                                     UnresolvedSetIterator End) {
-  assert(!Results && "Results already initialized!");
-  NumResults = End - Begin;
-  if (NumResults) {
-    Results = static_cast<DeclAccessPair *>(
-        C.Allocate(sizeof(DeclAccessPair) * NumResults,
-
-                   alignof(DeclAccessPair)));
-    memcpy(Results, Begin.I, NumResults * sizeof(DeclAccessPair));
-  }
+    setType(Context.DependentTy);
 }
 
-CXXRecordDecl *OverloadExpr::getNamingClass() const {
-  if (isa<UnresolvedLookupExpr>(this))
-    return cast<UnresolvedLookupExpr>(this)->getNamingClass();
-  else
-    return cast<UnresolvedMemberExpr>(this)->getNamingClass();
+OverloadExpr::OverloadExpr(StmtClass SC, EmptyShell Empty, unsigned NumResults,
+                           bool HasTemplateKWAndArgsInfo)
+    : Expr(SC, Empty) {
+  OverloadExprBits.NumResults = NumResults;
+  OverloadExprBits.HasTemplateKWAndArgsInfo = HasTemplateKWAndArgsInfo;
 }
 
 // DependentScopeDeclRefExpr
 DependentScopeDeclRefExpr::DependentScopeDeclRefExpr(
     QualType Ty, NestedNameSpecifierLoc QualifierLoc,
     SourceLocation TemplateKWLoc, const DeclarationNameInfo &NameInfo,
     const TemplateArgumentListInfo *Args)
     : Expr(
do {
     if (cast<CXXMethodDecl>(decl->getUnderlyingDecl()->getAsFunction())
             ->isStatic())
       return false;
   } while (++begin != end);
 
   return true;
 }
 
-UnresolvedMemberExpr::UnresolvedMemberExpr(const ASTContext &C,
-                                           bool HasUnresolvedUsing,
-                                           Expr *Base, QualType BaseType,
-                                           bool IsArrow,
-                                           SourceLocation OperatorLoc,
-                                           NestedNameSpecifierLoc QualifierLoc,
-                                           SourceLocation TemplateKWLoc,
-                                   const DeclarationNameInfo &MemberNameInfo,
-                                   const TemplateArgumentListInfo *TemplateArgs,
-                                           UnresolvedSetIterator Begin,
-                                           UnresolvedSetIterator End)
+UnresolvedMemberExpr::UnresolvedMemberExpr(
+    const ASTContext &Context, bool HasUnresolvedUsing, Expr *Base,
+    QualType BaseType, bool IsArrow, SourceLocation OperatorLoc,
+    NestedNameSpecifierLoc QualifierLoc, SourceLocation TemplateKWLoc,
+    const TemplateArgumentListInfo *TemplateArgs, UnresolvedSetIterator Begin,
     : OverloadExpr(
-          UnresolvedMemberExprClass, C, QualifierLoc, TemplateKWLoc,
+          UnresolvedMemberExprClass, Context, QualifierLoc, TemplateKWLoc,
           MemberNameInfo, TemplateArgs, Begin, End,
           // Dependent
           ((Base && Base->isTypeDependent()) || BaseType->isDependentType()),
           ((Base && Base->isInstantiationDependent()) ||
            BaseType->isInstantiationDependentType()),
           // Contains unexpanded parameter pack
           ((Base && Base->containsUnexpandedParameterPack()) ||
            BaseType->containsUnexpandedParameterPack())),
-      IsArrow(IsArrow), HasUnresolvedUsing(HasUnresolvedUsing), Base(Base),
-      BaseType(BaseType), OperatorLoc(OperatorLoc) {
+      Base(Base), BaseType(BaseType), OperatorLoc(OperatorLoc) {
+  UnresolvedMemberExprBits.IsArrow = IsArrow;
+  UnresolvedMemberExprBits.HasUnresolvedUsing = HasUnresolvedUsing;
+
   // Check whether all of the members are non-static member functions,
   // and if so, mark give this bound-member type instead of overload type.
   if (hasOnlyNonStaticMemberFunctions(Begin, End))
-    setType(C.BoundMemberTy);
+    setType(Context.BoundMemberTy);
 }
 
+UnresolvedMemberExpr::UnresolvedMemberExpr(EmptyShell Empty,
+                                           unsigned NumResults,
+                                           bool HasTemplateKWAndArgsInfo)
+    : OverloadExpr(UnresolvedMemberExprClass, Empty, NumResults,
+                   HasTemplateKWAndArgsInfo) {}
+
 bool UnresolvedMemberExpr::isImplicitAccess() const {
   if (!Base)
     return true;
 
   return cast<Expr>(Base)->isImplicitCXXThis();
 }
 
 UnresolvedMemberExpr *UnresolvedMemberExpr::Create(
-    const ASTContext &C, bool HasUnresolvedUsing, Expr *Base, QualType BaseType,
-    bool IsArrow, SourceLocation OperatorLoc,
+    const ASTContext &Context, bool HasUnresolvedUsing, Expr *Base,
+    QualType BaseType, bool IsArrow, SourceLocation OperatorLoc,
     NestedNameSpecifierLoc QualifierLoc, SourceLocation TemplateKWLoc,
     const DeclarationNameInfo &MemberNameInfo,
     const TemplateArgumentListInfo *TemplateArgs, UnresolvedSetIterator Begin,
     UnresolvedSetIterator End) {
+  unsigned NumResults = End - Begin;
   bool HasTemplateKWAndArgsInfo = TemplateArgs || TemplateKWLoc.isValid();
-  std::size_t Size =
-      totalSizeToAlloc<ASTTemplateKWAndArgsInfo, TemplateArgumentLoc>(
-          HasTemplateKWAndArgsInfo, TemplateArgs ? TemplateArgs->size() : 0);
-
-  void *Mem = C.Allocate(Size, alignof(UnresolvedMemberExpr));
+  unsigned NumTemplateArgs = TemplateArgs ? TemplateArgs->size() : 0;
+  unsigned Size = totalSizeToAlloc<DeclAccessPair, ASTTemplateKWAndArgsInfo,
+                                   TemplateArgumentLoc>(
+      NumResults, HasTemplateKWAndArgsInfo, NumTemplateArgs);
+  void *Mem = Context.Allocate(Size, alignof(UnresolvedMemberExpr));
   return new (Mem) UnresolvedMemberExpr(
-      C, HasUnresolvedUsing, Base, BaseType, IsArrow, OperatorLoc, QualifierLoc,
-      TemplateKWLoc, MemberNameInfo, TemplateArgs, Begin, End);
+      Context, HasUnresolvedUsing, Base, BaseType, IsArrow, OperatorLoc,
+      QualifierLoc, TemplateKWLoc, MemberNameInfo, TemplateArgs, Begin, End);
 }
 
-UnresolvedMemberExpr *
-UnresolvedMemberExpr::CreateEmpty(const ASTContext &C,
-                                  bool HasTemplateKWAndArgsInfo,
-                                  unsigned NumTemplateArgs) {
+UnresolvedMemberExpr *UnresolvedMemberExpr::CreateEmpty(
+    const ASTContext &Context, unsigned NumResults,
+    bool HasTemplateKWAndArgsInfo, unsigned NumTemplateArgs) {
   assert(NumTemplateArgs == 0 || HasTemplateKWAndArgsInfo);
-  std::size_t Size =
-      totalSizeToAlloc<ASTTemplateKWAndArgsInfo, TemplateArgumentLoc>(
-          HasTemplateKWAndArgsInfo, NumTemplateArgs);
-
-  void *Mem = C.Allocate(Size, alignof(UnresolvedMemberExpr));
-  auto *E = new (Mem) UnresolvedMemberExpr(EmptyShell());
-  E->HasTemplateKWAndArgsInfo = HasTemplateKWAndArgsInfo;
-  return E;
+  unsigned Size = totalSizeToAlloc<DeclAccessPair, ASTTemplateKWAndArgsInfo,
+                                   TemplateArgumentLoc>(
+      NumResults, HasTemplateKWAndArgsInfo, NumTemplateArgs);
+  void *Mem = Context.Allocate(Size, alignof(UnresolvedMemberExpr));
+  return new (Mem)
+      UnresolvedMemberExpr(EmptyShell(), NumResults, HasTemplateKWAndArgsInfo);
 }
 
-CXXRecordDecl *UnresolvedMemberExpr::getNamingClass() const {
+CXXRecordDecl *UnresolvedMemberExpr::getNamingClass() {
   // Unlike for UnresolvedLookupExpr, it is very easy to re-derive this.
 
   // If there was a nested name specifier, it names the naming class.
   // It can't be dependent: after all, we were actually able to do the
   // lookup.
   CXXRecordDecl *Record = nullptr;
   auto *NNS = getQualifier();
   if (NNS && NNS->getKind() != NestedNameSpecifier::Super) {

lib/Serialization/ASTReaderStmt.cpp

ASTStmtReader::VisitCXXUnresolvedConstructExpr(CXXUnresolvedConstructExpr *E) {
   E->TSI = GetTypeSourceInfo();
   E->setLParenLoc(ReadSourceLocation());
   E->setRParenLoc(ReadSourceLocation());
 }
 
 void ASTStmtReader::VisitOverloadExpr(OverloadExpr *E) {
   VisitExpr(E);
 
-  if (Record.readInt()) // HasTemplateKWAndArgsInfo
+  unsigned NumResults = Record.readInt();
+  bool HasTemplateKWAndArgsInfo = Record.readInt();
+  assert((E->getNumDecls() == NumResults) && "Wrong NumResults!");
+  assert((E->hasTemplateKWAndArgsInfo() == HasTemplateKWAndArgsInfo) &&
+         "Wrong HasTemplateKWAndArgsInfo!");
+
+  if (HasTemplateKWAndArgsInfo) {
+    unsigned NumTemplateArgs = Record.readInt();
     ReadTemplateKWAndArgsInfo(*E->getTrailingASTTemplateKWAndArgsInfo(),
                               E->getTrailingTemplateArgumentLoc(),
-                              /*NumTemplateArgs=*/Record.readInt());
+                              NumTemplateArgs);
+    assert((E->getNumTemplateArgs() == NumTemplateArgs) &&
+           "Wrong NumTemplateArgs!");
+  }
 
-  unsigned NumDecls = Record.readInt();
   UnresolvedSet<8> Decls;
-  for (unsigned i = 0; i != NumDecls; ++i) {
+  for (unsigned I = 0; I != NumResults; ++I) {
     auto *D = ReadDeclAs<NamedDecl>();
     auto AS = (AccessSpecifier)Record.readInt();
     Decls.addDecl(D, AS);
   }
-  E->initializeResults(Record.getContext(), Decls.begin(), Decls.end());
+
+  DeclAccessPair *Results = E->getTrailingResults();
+  UnresolvedSetIterator Iter = Decls.begin();
+  for (unsigned I = 0; I != NumResults; ++I) {
+    Results[I] = (Iter + I).getPair();
+  }
 
   ReadDeclarationNameInfo(E->NameInfo);
   E->QualifierLoc = Record.readNestedNameSpecifierLoc();
 }
 
 void ASTStmtReader::VisitUnresolvedMemberExpr(UnresolvedMemberExpr *E) {
   VisitOverloadExpr(E);
-  E->IsArrow = Record.readInt();
-  E->HasUnresolvedUsing = Record.readInt();
+  E->UnresolvedMemberExprBits.IsArrow = Record.readInt();
+  E->UnresolvedMemberExprBits.HasUnresolvedUsing = Record.readInt();
   E->Base = Record.readSubExpr();
   E->BaseType = Record.readType();
   E->OperatorLoc = ReadSourceLocation();
 }
 
 void ASTStmtReader::VisitUnresolvedLookupExpr(UnresolvedLookupExpr *E) {
   VisitOverloadExpr(E);
-  E->RequiresADL = Record.readInt();
-  E->Overloaded = Record.readInt();
+  E->UnresolvedLookupExprBits.RequiresADL = Record.readInt();
+  E->UnresolvedLookupExprBits.Overloaded = Record.readInt();
   E->NamingClass = ReadDeclAs<CXXRecordDecl>();
 }
 
 void ASTStmtReader::VisitTypeTraitExpr(TypeTraitExpr *E) {
   VisitExpr(E);
   E->TypeTraitExprBits.NumArgs = Record.readInt();
   E->TypeTraitExprBits.Kind = Record.readInt();
   E->TypeTraitExprBits.Value = Record.readInt();
case EXPR_CXX_DEPENDENT_SCOPE_DECL_REF:
       break;
 
     case EXPR_CXX_UNRESOLVED_CONSTRUCT:
       S = CXXUnresolvedConstructExpr::CreateEmpty(Context,
                               /*NumArgs=*/Record[ASTStmtReader::NumExprFields]);
       break;
 
     case EXPR_CXX_UNRESOLVED_MEMBER:
-      S = UnresolvedMemberExpr::CreateEmpty(Context,
-         /*HasTemplateKWAndArgsInfo=*/Record[ASTStmtReader::NumExprFields],
-                  /*NumTemplateArgs=*/Record[ASTStmtReader::NumExprFields]
-                                   ? Record[ASTStmtReader::NumExprFields + 1]
-                                   : 0);
+      S = UnresolvedMemberExpr::CreateEmpty(
+          Context,
+          /*NumResults=*/Record[ASTStmtReader::NumExprFields],
+          /*HasTemplateKWAndArgsInfo=*/Record[ASTStmtReader::NumExprFields + 1],
+          /*NumTemplateArgs=*/
+          Record[ASTStmtReader::NumExprFields + 1]
+              ? Record[ASTStmtReader::NumExprFields + 2]
       break;
 
     case EXPR_CXX_UNRESOLVED_LOOKUP:
-      S = UnresolvedLookupExpr::CreateEmpty(Context,
-         /*HasTemplateKWAndArgsInfo=*/Record[ASTStmtReader::NumExprFields],
-                  /*NumTemplateArgs=*/Record[ASTStmtReader::NumExprFields]
-                                   ? Record[ASTStmtReader::NumExprFields + 1]
-                                   : 0);
+      S = UnresolvedLookupExpr::CreateEmpty(
+          Context,
+          /*NumResults=*/Record[ASTStmtReader::NumExprFields],
+          /*HasTemplateKWAndArgsInfo=*/Record[ASTStmtReader::NumExprFields + 1],
+          /*NumTemplateArgs=*/
+          Record[ASTStmtReader::NumExprFields + 1]
+              ? Record[ASTStmtReader::NumExprFields + 2]
       break;
 
     case EXPR_TYPE_TRAIT:
       S = TypeTraitExpr::CreateDeserialized(Context,
             Record[ASTStmtReader::NumExprFields]);
       break;
 
     case EXPR_ARRAY_TYPE_TRAIT:

lib/Serialization/ASTWriterStmt.cpp

ASTStmtWriter::VisitCXXUnresolvedConstructExpr(CXXUnresolvedConstructExpr *E) {
   Record.AddSourceLocation(E->getLParenLoc());
   Record.AddSourceLocation(E->getRParenLoc());
   Code = serialization::EXPR_CXX_UNRESOLVED_CONSTRUCT;
 }
 
 void ASTStmtWriter::VisitOverloadExpr(OverloadExpr *E) {
   VisitExpr(E);
 
-  // Don't emit anything here, HasTemplateKWAndArgsInfo must be
-  // emitted first.
-
-  Record.push_back(E->HasTemplateKWAndArgsInfo);
-  if (E->HasTemplateKWAndArgsInfo) {
+  Record.push_back(E->getNumDecls());
+  Record.push_back(E->hasTemplateKWAndArgsInfo());
+  if (E->hasTemplateKWAndArgsInfo()) {
     const ASTTemplateKWAndArgsInfo &ArgInfo =
         *E->getTrailingASTTemplateKWAndArgsInfo();
     Record.push_back(ArgInfo.NumTemplateArgs);
     AddTemplateKWAndArgsInfo(ArgInfo, E->getTrailingTemplateArgumentLoc());
   }
 
-  Record.push_back(E->getNumDecls());
-  for (OverloadExpr::decls_iterator
-         OvI = E->decls_begin(), OvE = E->decls_end(); OvI != OvE; ++OvI) {
+  for (OverloadExpr::decls_iterator OvI = E->decls_begin(),
+                                    OvE = E->decls_end();
+       OvI != OvE; ++OvI) {
     Record.AddDeclRef(OvI.getDecl());
     Record.push_back(OvI.getAccess());
   }
 
-  Record.AddDeclarationNameInfo(E->NameInfo);
+  Record.AddDeclarationNameInfo(E->getNameInfo());
   Record.AddNestedNameSpecifierLoc(E->getQualifierLoc());
 }
 
 void ASTStmtWriter::VisitUnresolvedMemberExpr(UnresolvedMemberExpr *E) {
   VisitOverloadExpr(E);
   Record.push_back(E->isArrow());
   Record.push_back(E->hasUnresolvedUsing());
   Record.AddStmt(!E->isImplicitAccess() ? E->getBase() : nullptr);