- Remember the fact that an object has been added to the

runtime/vm/scavenger.cc

Index: runtime/vm/scavenger.cc
===================================================================
--- runtime/vm/scavenger.cc	(revision 22083)
+++ runtime/vm/scavenger.cc	(working copy)
@@ -19,14 +19,14 @@
 
 namespace dart {
 
-// Scavenger uses RawObject::kFreeBit to distinguish forwaded and non-forwarded
-// objects because scavenger can never encounter free list element during
-// evacuation and thus all objects scavenger encounters have
-// kFreeBit cleared.
+// Scavenger uses RawObject::kMarkBit to distinguish forwaded and non-forwarded
+// objects because scavenger can never encounter marked elements during
+// evacuation and thus all objects scavenger encounters have the
+// kMarkBit cleared.
 enum {
-  kForwardingMask = 1,
+  kForwardingMask = RawObject::kMarkBit,
   kNotForwarded = 0,
-  kForwarded = 1,
+  kForwarded = kForwardingMask,
 };
 
 
@@ -122,7 +122,10 @@
     ASSERT(!heap_->CodeContains(ptr));
     ASSERT(heap_->Contains(ptr));
     // If the newly written object is not a new object, drop it immediately.
-    if (!obj->IsNewObject()) return;
+    if (!obj->IsNewObject() || visiting_old_object_->IsRemembered()) {
+      return;
+    }
+    visiting_old_object_->SetRememberedBit();
     isolate()->store_buffer()->AddPointer(
         reinterpret_cast<uword>(visiting_old_object_));
   }
@@ -299,7 +302,6 @@
   // Verify assumptions about the first word in objects which the scavenger is
   // going to use for forwarding pointers.
   ASSERT(Object::tags_offset() == 0);
-  ASSERT(kForwardingMask == (1 << RawObject::kFreeBit));
 
   // Allocate the virtual memory for this scavenge heap.
   space_ = VirtualMemory::Reserve(max_capacity);
@@ -399,6 +401,8 @@
     for (intptr_t i = 0; i < size; i++) {
       RawObject* raw_object = reinterpret_cast<RawObject*>(set->At(i));
       if (raw_object != NULL) {
+        ASSERT(raw_object->IsRemembered());
+        raw_object->ClearRememberedBit();
         visitor->VisitingOldObject(raw_object);
         raw_object->VisitPointers(visitor);
         handled++;
@@ -536,6 +540,7 @@
         // Resolve or copy all objects referred to by the current object. This
         // can potentially push more objects on this stack as well as add more
         // objects to be resolved in the to space.
+        ASSERT(!raw_object->IsRemembered());
         visitor->VisitingOldObject(raw_object);
         raw_object->VisitPointers(visitor);
       }