Reland r19897 "Fix memory leak caused by treating Code::next_code_link as strong in marker.

src/objects.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1880 matching lines @@
   static const int kHeaderSize = kMapOffset + kPointerSize;
 
   STATIC_CHECK(kMapOffset == Internals::kHeapObjectMapOffset);
 
  protected:
   // helpers for calling an ObjectVisitor to iterate over pointers in the
   // half-open range [start, end) specified as integer offsets
   inline void IteratePointers(ObjectVisitor* v, int start, int end);
   // 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 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>
@@ skipping 3312 matching lines @@
   // [handler_table]: Fixed array containing offsets of exception handlers.
   DECL_ACCESSORS(handler_table, FixedArray)
 
   // [deoptimization_data]: Array containing data for deopt.
   DECL_ACCESSORS(deoptimization_data, FixedArray)
 
   // [raw_type_feedback_info]: This field stores various things, depending on
   // the kind of the code object.
   //   FUNCTION           => type feedback information.
   //   STUB               => various things, e.g. a SMI
-  //   OPTIMIZED_FUNCTION => the next_code_link for optimized code list.
   DECL_ACCESSORS(raw_type_feedback_info, Object)
   inline Object* type_feedback_info();
   inline void set_type_feedback_info(
       Object* value, WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
   inline int stub_info();
   inline void set_stub_info(int info);
 
   // [next_code_link]: Link for lists of optimized or deoptimized code.
   // Note that storage for this field is overlapped with typefeedback_info.
   DECL_ACCESSORS(next_code_link, Object)
@@ skipping 312 matching lines @@
   static const int kMaxLoopNestingMarker = 6;
 
   // Layout description.
   static const int kInstructionSizeOffset = HeapObject::kHeaderSize;
   static const int kRelocationInfoOffset = kInstructionSizeOffset + kIntSize;
   static const int kHandlerTableOffset = kRelocationInfoOffset + kPointerSize;
   static const int kDeoptimizationDataOffset =
       kHandlerTableOffset + kPointerSize;
   static const int kTypeFeedbackInfoOffset =
       kDeoptimizationDataOffset + kPointerSize;
-  static const int kNextCodeLinkOffset = kTypeFeedbackInfoOffset;  // Shared.
-  static const int kGCMetadataOffset = kTypeFeedbackInfoOffset + kPointerSize;
+  static const int kNextCodeLinkOffset = kTypeFeedbackInfoOffset + kPointerSize;
+  static const int kGCMetadataOffset = kNextCodeLinkOffset + kPointerSize;
   static const int kICAgeOffset =
       kGCMetadataOffset + kPointerSize;
   static const int kFlagsOffset = kICAgeOffset + kIntSize;
   static const int kKindSpecificFlags1Offset = kFlagsOffset + kIntSize;
   static const int kKindSpecificFlags2Offset =
       kKindSpecificFlags1Offset + kIntSize;
   // Note: We might be able to squeeze this into the flags above.
   static const int kPrologueOffset = kKindSpecificFlags2Offset + kIntSize;
   static const int kConstantPoolOffset = kPrologueOffset + kPointerSize;
 
@@ skipping 5123 matching lines @@
  public:
   virtual ~ObjectVisitor() {}
 
   // Visits a contiguous arrays of pointers in the half-open range
   // [start, end). Any or all of the values may be modified on return.
   virtual void VisitPointers(Object** start, Object** end) = 0;
 
   // Handy shorthand for visiting a single pointer.
   virtual void VisitPointer(Object** p) { VisitPointers(p, p + 1); }
 
+  // Visit weak next_code_link in Code object.
+  virtual void VisitNextCodeLink(Object** p) { VisitPointers(p, p + 1); }
+
   // To allow lazy clearing of inline caches the visitor has
   // a rich interface for iterating over Code objects..
 
   // Visits a code target in the instruction stream.
   virtual void VisitCodeTarget(RelocInfo* rinfo);
 
   // Visits a code entry in a JS function.
   virtual void VisitCodeEntry(Address entry_address);
 
   // Visits a global property cell reference in the instruction stream.
@@ skipping 65 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_