Move both dynamic and static object body visiting logic to BodyDescriptorBase class.

src/objects.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 1619 matching lines @@
   // as above, for the single element at "offset"
   inline void IteratePointer(ObjectVisitor* v, int offset);
   // as above, for the next code link of a code object.
   inline void IterateNextCodeLink(ObjectVisitor* v, int offset);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(HeapObject);
 };
 
 
+// This class base class for object's body descriptors.

[Michael Starzinger, 2015/11/05 13:10:25]

nit: "This is the base class ..."?

[Igor Sheludko, 2015/11/05 13:45:12]

Done.

+class BodyDescriptorBase {
+ protected:
+  static inline void IterateBodyImpl(HeapObject* obj, int start_offset,
+                                     int end_offset, ObjectVisitor* v);
+
+  template <typename StaticVisitor>
+  static inline void IterateBodyImpl(HeapObject* obj, int start_offset,
+                                     int end_offset);
+};
+
+
 // This class describes a body of an object of a fixed size
 // in which all pointer fields are located in the [start_offset, end_offset)
 // interval.
-template<int start_offset, int end_offset, int size>
-class FixedBodyDescriptor {
+template <int start_offset, int end_offset, int size>
+class FixedBodyDescriptor : public BodyDescriptorBase {
  public:
   static const int kStartOffset = start_offset;
   static const int kEndOffset = end_offset;
   static const int kSize = size;
 
-  static inline void IterateBody(HeapObject* obj, ObjectVisitor* v);
+  static inline void IterateBody(HeapObject* obj, ObjectVisitor* v) {
+    IterateBodyImpl(obj, start_offset, end_offset, v);
+  }
 
-  template<typename StaticVisitor>
+  template <typename StaticVisitor>
   static inline void IterateBody(HeapObject* obj) {
-    StaticVisitor::VisitPointers(HeapObject::RawField(obj, start_offset),
-                                 HeapObject::RawField(obj, end_offset));
+    IterateBodyImpl<StaticVisitor>(obj, start_offset, end_offset);
+  }
+};
+
+
+// This base class describes a body of an object of a variable size
+// in which all pointer fields are located in the [start_offset, object_size)
+// interval.
+template <int start_offset>
+class FlexibleBodyDescriptorBase : public BodyDescriptorBase {

[Michael Starzinger, 2015/11/05 13:10:25]

Is there a particular reason FlexibleBodyDescriptorBase and
FlexibleBodyDescriptor have to be separate classes? Could we just merge them
into FlexibleBodyDescriptor instead?

[Michael Starzinger, 2015/11/05 13:44:46]

As discussed offline: This is used by FixedArray::BodyDescriptor, didn't see
that before. It's fine then. Please disregard this comment.

[Igor Sheludko, 2015/11/05 13:45:12]

I tried to avoid the confusion, since the FixedArray::BodyDescriptor defines
it's own SizeOf() method. So FixedArray::BodyDescriptor inherits from the
FlexibleBodyDescriptorBase which does not have a SizeOf().

+ public:
+  static const int kStartOffset = start_offset;
+
+  static inline void IterateBody(HeapObject* obj, int object_size,
+                                 ObjectVisitor* v) {
+    IterateBodyImpl(obj, start_offset, object_size, v);
+  }
+
+  template <typename StaticVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size) {
+    IterateBodyImpl<StaticVisitor>(obj, start_offset, object_size);
   }
 };
 
 
 // This class describes a body of an object of a variable size
 // in which all pointer fields are located in the [start_offset, object_size)
-// interval.
-template<int start_offset>
-class FlexibleBodyDescriptor {
+// interval. The size of the object is taken from the map.
+template <int start_offset>
+class FlexibleBodyDescriptor : public FlexibleBodyDescriptorBase<start_offset> {
  public:
-  static const int kStartOffset = start_offset;
-
-  static inline void IterateBody(HeapObject* obj,
-                                 int object_size,
-                                 ObjectVisitor* v);
-
-  template<typename StaticVisitor>
-  static inline void IterateBody(HeapObject* obj, int object_size) {
-    StaticVisitor::VisitPointers(HeapObject::RawField(obj, start_offset),
-                                 HeapObject::RawField(obj, object_size));
-  }
+  static inline int SizeOf(Map* map, HeapObject* object);
 };
 
 
 // The HeapNumber class describes heap allocated numbers that cannot be
 // represented in a Smi (small integer)
 class HeapNumber: public HeapObject {
  public:
   // [value]: number value.
   inline double value() const;
   inline void set_value(double value);
@@ skipping 783 matching lines @@
   // to the same object requires fewer allocations and copies.
   static const int kFieldsAdded = 3;
 
   // Layout description.
   static const int kPropertiesOffset = HeapObject::kHeaderSize;
   static const int kElementsOffset = kPropertiesOffset + kPointerSize;
   static const int kHeaderSize = kElementsOffset + kPointerSize;
 
   STATIC_ASSERT(kHeaderSize == Internals::kJSObjectHeaderSize);
 
-  class BodyDescriptor : public FlexibleBodyDescriptor<kPropertiesOffset> {
-   public:
-    static inline int SizeOf(Map* map, HeapObject* object);
-  };
+  typedef FlexibleBodyDescriptor<kPropertiesOffset> BodyDescriptor;
 
   Context* GetCreationContext();
 
   // Enqueue change record for Object.observe. May cause GC.
   MUST_USE_RESULT static MaybeHandle<Object> EnqueueChangeRecord(
       Handle<JSObject> object, const char* type, Handle<Name> name,
       Handle<Object> old_value);
 
   // Gets the number of currently used elements.
   int GetFastElementsUsage();
@@ skipping 158 matching lines @@
   // Swap two elements in a pair of arrays.  If this array and the
   // numbers array are the same object, the elements are only swapped
   // once.
   void SwapPairs(FixedArray* numbers, int i, int j);
 
   // Sort prefix of this array and the numbers array as pairs wrt. the
   // numbers.  If the numbers array and the this array are the same
   // object, the prefix of this array is sorted.
   void SortPairs(FixedArray* numbers, uint32_t len);
 
-  class BodyDescriptor : public FlexibleBodyDescriptor<kHeaderSize> {
+  class BodyDescriptor : public FlexibleBodyDescriptorBase<kHeaderSize> {
    public:
     static inline int SizeOf(Map* map, HeapObject* object);
   };
 
  protected:
   // Set operation on FixedArray without using write barriers. Can
   // only be used for storing old space objects or smis.
   static inline void NoWriteBarrierSet(FixedArray* array,
                                        int index,
                                        Object* value);
@@ skipping 8035 matching lines @@
   // Visits a handle that has an embedder-assigned class ID.
   virtual void VisitEmbedderReference(Object** p, uint16_t class_id) {}
 
   // Intended for serialization/deserialization checking: insert, or
   // check for the presence of, a tag at this position in the stream.
   // Also used for marking up GC roots in heap snapshots.
   virtual void Synchronize(VisitorSynchronization::SyncTag tag) {}
 };
 
 
-class StructBodyDescriptor : public
-  FlexibleBodyDescriptor<HeapObject::kHeaderSize> {
- public:
-  static inline int SizeOf(Map* map, HeapObject* object);
-};
+typedef FlexibleBodyDescriptor<HeapObject::kHeaderSize> StructBodyDescriptor;
 
 
 // BooleanBit is a helper class for setting and getting a bit in an integer.
 class BooleanBit : public AllStatic {
  public:
   static inline bool get(int value, int bit_position) {
     return (value & (1 << bit_position)) != 0;
   }
 
   static inline int set(int value, int bit_position, bool v) {
     if (v) {
       value |= (1 << bit_position);
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_