--- a/hotspot/src/share/vm/gc/g1/g1BlockOffsetTable.cpp	Wed Dec 07 13:51:20 2016 +0100
+++ b/hotspot/src/share/vm/gc/g1/g1BlockOffsetTable.cpp	Fri Feb 24 10:41:56 2017 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -79,7 +79,9 @@
   _space(gsp),
   _next_offset_threshold(NULL),
   _next_offset_index(0)
-{ }
+{
+  debug_only(_object_can_span = false;)
+}
 
 // The arguments follow the normal convention of denoting
 // a right-open interval: [start, end)
@@ -364,6 +366,12 @@
   }
 }
 
+#ifdef ASSERT
+void G1BlockOffsetTablePart::set_object_can_span(bool can_span) {
+  _object_can_span = can_span;
+}
+#endif
+
 #ifndef PRODUCT
 void
 G1BlockOffsetTablePart::print_on(outputStream* out) {