Make VerifyMarking work in the presence of grey objects

src/heap/mark-compact.cc

Index: src/heap/mark-compact.cc
diff --git a/src/heap/mark-compact.cc b/src/heap/mark-compact.cc
index 44262e42b162b58974cf7b2092ea141047856d2a..ab248476165e5dbd1d9d3083e7c7cb1c8b934279 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -102,6 +102,10 @@ static void VerifyMarking(Heap* heap, Address bottom, Address top) {
       CHECK(current >= next_object_must_be_here_or_later);
       object->Iterate(&visitor);
       next_object_must_be_here_or_later = current + object->Size();
+      // Take into account that a marked objected is at least two pointers in

[Hannes Payer (out of office), 2015/03/09 13:49:25]

object

+      // size. If we don't skip one word, the next word gets detected as an
+      // object as well.
+      current += kPointerSize;

[Hannes Payer (out of office), 2015/03/09 13:49:25]

Now the verifier would allow grey object in the final transitive closure. I
don't think we want that. You could add an additional parameter that forces you
to check for black and/or grey.

     }
   }
 }