Changed scavenge GC to collect unmodified references

src/global-handles.h

Index: src/global-handles.h
diff --git a/src/global-handles.h b/src/global-handles.h
index 0ee8c20a375adaea6803c11034686b08d806f9d8..ecb0c1cb065d587bc27d686e748ebac1c8affdc1 100644
--- a/src/global-handles.h
+++ b/src/global-handles.h
@@ -204,7 +204,7 @@ class GlobalHandles {
   // them as pending.
   void IdentifyWeakHandles(WeakSlotCallback f);
 
-  // NOTE: Three ...NewSpace... functions below are used during
+  // NOTE: Five ...NewSpace... functions below are used during
   // scavenge collections and iterate over sets of handles that are
   // guaranteed to contain all handles holding new space objects (but
   // may also include old space objects).
@@ -220,6 +220,18 @@ class GlobalHandles {
   // See the note above.
   void IterateNewSpaceWeakIndependentRoots(ObjectVisitor* v);
 
+  // Finds weak independent or unmodified handles satisfying
+  // the callback predicate and marks them as pending. See the note above.
+  void IdentifyNewSpaceWeakUnModifiedHandles(WeakSlotCallbackWithHeap f);
+
+  // Iterates over weak independent or unmodified handles.
+  // See the note above.
+  void IterateNewSpaceWeakUnModifiedRoots(ObjectVisitor* v);
+
+  // Identify unmodified objects that are in weak state and marks them partially
+  // independent

[rmcilroy, 2015/09/28 17:32:46]

update comment please.

[mythria, 2015/10/02 15:29:16]

Done.

+  void IdentifyWeakUnmodifiedObjects(WeakSlotCallback can_skip);
+
   // Iterate over objects in object groups that have at least one object
   // which requires visiting. The callback has to return true if objects
   // can be skipped and false otherwise.