--- old/src/share/vm/opto/compile.cpp	2017-07-25 14:58:33.243795834 +0200
+++ new/src/share/vm/opto/compile.cpp	2017-07-25 14:58:28.948804791 +0200
@@ -1970,6 +1970,7 @@
 }
 
 void Compile::add_value_type_ptr(ValueTypePtrNode* n) {
+  assert(can_add_value_type_ptr(), "too late");
   assert(!_value_type_ptr_nodes->contains(n), "duplicate entry");
   _value_type_ptr_nodes->append(n);
 }
@@ -1983,6 +1984,7 @@
     igvn.replace_node(vtptr, vtptr->get_oop());
   }
   assert(value_type_ptr_count() == 0, "should be empty");
+  _value_type_ptr_nodes = NULL;
   igvn.optimize();
 }