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

src/mark-compact.cc

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@@ skipping 1842 matching lines @@
     : collector_(heap->mark_compact_collector()) { }
 
   void VisitPointer(Object** p) {
     MarkObjectByPointer(p);
   }
 
   void VisitPointers(Object** start, Object** end) {
     for (Object** p = start; p < end; p++) MarkObjectByPointer(p);
   }
 
+  // Skip the weak next code link in a code object.
+  void VisitNextCodeLink(Object** p) { }

[Michael Starzinger, 2014/03/06 13:43:52]

This should actually be unreachable, because there is no "NextCodeLink" in the
root-set. There might be code objects in the root-set, but their body will be
visited using the static visitor (see line 1882) below. Can we add an
UNREACHABLE() assertion instead?

[ulan, 2014/03/13 14:06:52]

As discussed offline, this is called in ProcessTopOptimizedFrame. Added a
comment.

+
  private:
   void MarkObjectByPointer(Object** p) {
     if (!(*p)->IsHeapObject()) return;
 
     // Replace flat cons strings in place.
     HeapObject* object = ShortCircuitConsString(p);
     MarkBit mark_bit = Marking::MarkBitFrom(object);
     if (mark_bit.Get()) return;
 
     Map* map = object->map();
@@ skipping 2604 matching lines @@
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 
 
 } }  // namespace v8::internal