[heap] Avoid the use of cells to point from code to new-space objects.

src/heap/mark-compact.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_HEAP_MARK_COMPACT_H_
 #define V8_HEAP_MARK_COMPACT_H_
 
 #include <deque>
 
 #include "src/base/bits.h"
@@ skipping 523 matching lines @@
     return Page::FromAddress(reinterpret_cast<Address>(host))
         ->ShouldSkipEvacuationSlotRecording();
   }
 
   INLINE(static bool IsOnEvacuationCandidate(Object* obj)) {
     return Page::FromAddress(reinterpret_cast<Address>(obj))
         ->IsEvacuationCandidate();
   }
 
   void RecordRelocSlot(Code* host, RelocInfo* rinfo, Object* target);
+  void RecordRelocSlotToNewSpace(Code* host, RelocInfo* rinfo, Object* target);

[ulan, 2016/06/08 14:37:00]

This function doesn't belong to incremental marking and mark compactor because
it is recording slot for scavenger.

Let's move it to Heap new  Heap::RecordWrite and call it 
Heap::RecordWriteToCode.

[ahaas, 2016/06/09 10:34:32]

Done. I had to put the implementation into heap.cc because of the inline header
nightmare.

   void RecordCodeEntrySlot(HeapObject* host, Address slot, Code* target);
   void RecordCodeTargetPatch(Address pc, Code* target);
   INLINE(void RecordSlot(HeapObject* object, Object** slot, Object* target));
   INLINE(void ForceRecordSlot(HeapObject* object, Object** slot,
                               Object* target));
 
   void UpdateSlots(SlotsBuffer* buffer);
   void UpdateSlotsRecordedIn(SlotsBuffer* buffer);
 
   void InvalidateCode(Code* code);
@@ skipping 336 matching lines @@
  private:
   MarkCompactCollector* collector_;
 };
 
 
 const char* AllocationSpaceName(AllocationSpace space);
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_MARK_COMPACT_H_