- Removed the kWatchedBit and the associated weak property handling

runtime/vm/raw_object.h

Index: runtime/vm/raw_object.h
diff --git a/runtime/vm/raw_object.h b/runtime/vm/raw_object.h
index 977ba55040acdc93904c958016db44714e6dce62..e86840f83e6bf997188826329287c621dda8f8cd 100644
--- a/runtime/vm/raw_object.h
+++ b/runtime/vm/raw_object.h
@@ -256,7 +256,7 @@ class RawObject {
   // The tags field which is a part of the object header uses the following
   // bit fields for storing tags.
   enum TagBits {
-    kWatchedBit = 0,
+    kTheBitFormerlyKnownAsTheWatchedBit = 0,

[Ivan Posva, 2016/05/20 18:13:35]

I am planning to move the bits up by one separately.

     kMarkBit = 1,
     kCanonicalBit = 2,
     kVMHeapObjectBit = 3,
@@ -374,21 +374,6 @@ class RawObject {
     return TryAcquireTagBit<MarkBit>();
   }
 
-  // Support for GC watched bit.
-  // TODO(iposva): Get rid of this.
-  bool IsWatched() const {
-    return WatchedBit::decode(ptr()->tags_);
-  }
-  void SetWatchedBitUnsynchronized() {
-    ASSERT(!IsWatched());
-    uword tags = ptr()->tags_;
-    ptr()->tags_ = WatchedBit::update(true, tags);
-  }
-  void ClearWatchedBitUnsynchronized() {
-    uword tags = ptr()->tags_;
-    ptr()->tags_ = WatchedBit::update(false, tags);
-  }
-
   // Support for object tags.
   bool IsCanonical() const {
     return CanonicalObjectTag::decode(ptr()->tags_);
@@ -521,8 +506,6 @@ CLASS_LIST_TYPED_DATA(DEFINE_IS_CID)
  private:
   uword tags_;  // Various object tags (bits).
 
-  class WatchedBit : public BitField<uword, bool, kWatchedBit, 1> {};
-
   class MarkBit : public BitField<uword, bool, kMarkBit, 1> {};
 
   class RememberedBit : public BitField<uword, bool, kRememberedBit, 1> {};
@@ -2174,7 +2157,10 @@ class RawWeakProperty : public RawInstance {
     return reinterpret_cast<RawObject**>(&ptr()->value_);
   }
 
-  friend class DelaySet;
+  // Linked list is chaining all pending weak properties.
+  // Untyped to make it clear that it is not to be visited by GC.
+  uword next_;
+
   friend class GCMarker;
   template<bool> friend class MarkingVisitorBase;
   friend class Scavenger;