[heap] Fine-grained JSArrayBuffer tracking

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 3ec0a3e229c699fdb50460cdcd0ae70f342f00ba..7dd4bb0bac9ef4e7a588feed50390490e6dce583 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -1626,8 +1626,6 @@ void Heap::Scavenge() {
 
   scavenge_collector_->SelectScavengingVisitorsTable();
 
-  array_buffer_tracker()->PrepareDiscoveryInNewSpace();
-
   // Flip the semispaces.  After flipping, to space is empty, from space has
   // live objects.
   new_space_.Flip();
@@ -1735,7 +1733,7 @@ void Heap::Scavenge() {
   // Set age mark.
   new_space_.set_age_mark(new_space_.top());
 
-  array_buffer_tracker()->FreeDead(true);
+  array_buffer_tracker()->FreeDeadInNewSpace();
 
   // Update how much has survived scavenge.
   IncrementYoungSurvivorsCounter(static_cast<int>(
@@ -2015,7 +2013,9 @@ HeapObject* Heap::DoubleAlignForDeserialization(HeapObject* object, int size) {
 
 
 void Heap::RegisterNewArrayBuffer(JSArrayBuffer* buffer) {
-  return array_buffer_tracker()->RegisterNew(buffer);
+  const bool track_live =
+      Page::FromAddress(buffer->address())->IsFlagSet(Page::BLACK_PAGE);

[Hannes Payer (out of office), 2016/05/20 12:21:17]

Instead of checking for black page, it would be better to check for object color
to be independent of black pages.

[Michael Lippautz, 2016/05/23 08:41:00]

Done.

+  return array_buffer_tracker()->RegisterNew(buffer, track_live);
 }