[heap] Black allocation.

src/objects-inl.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.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 2020 matching lines @@
   // Either the garbage collector is clearing the cell or we are simply
   // initializing the root empty weak cell.
   DCHECK(GetHeap()->gc_state() == Heap::MARK_COMPACT ||
          this == GetHeap()->empty_weak_cell());
   WRITE_FIELD(this, kValueOffset, Smi::FromInt(0));
 }
 
 
 void WeakCell::initialize(HeapObject* val) {
   WRITE_FIELD(this, kValueOffset, val);
-  Heap* heap = GetHeap();
   // We just have to execute the generational barrier here because we never
   // mark through a weak cell and collect evacuation candidates when we process
   // all weak cells.
-  if (heap->InNewSpace(val)) {
-    heap->RecordWrite(address(), kValueOffset);
-  }
+  WriteBarrierMode mode =
+      Page::FromAddress(this->address())->IsFlagSet(Page::BLACK_PAGE)
+          ? UPDATE_WRITE_BARRIER

[ulan, 2016/02/10 10:27:39]

Invoking the marking visitor of the weak cell might be more consistent.

The same holds for TransitionArray, WeakCollection, JSArrayBuffer, JSFunction,
SharedFunctionInfo, Map

[Hannes Payer (out of office), 2016/02/11 18:18:07]

As discussed offline, this change was done on purpose. WeakCells on black pages
become strong. If floating garbage increases significantly because of that
change, we have to look into that problem.

+          : UPDATE_WEAK_WRITE_BARRIER;
+  CONDITIONAL_WRITE_BARRIER(GetHeap(), this, kValueOffset, val, mode);
 }
 
 
 bool WeakCell::cleared() const { return value() == Smi::FromInt(0); }
 
 
 Object* WeakCell::next() const { return READ_FIELD(this, kNextOffset); }
 
 
 void WeakCell::set_next(Object* val, WriteBarrierMode mode) {
@@ skipping 5781 matching lines @@
 #undef WRITE_INT64_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_INL_H_