--- old/src/hotspot/share/opto/phaseX.cpp	2020-01-17 17:14:39.249115648 +0100
+++ new/src/hotspot/share/opto/phaseX.cpp	2020-01-17 17:14:39.145115654 +0100
@@ -2106,6 +2106,10 @@
     default:
       break;
     }
+    if (UseShenandoahGC) {
+      // TODO: Should we call this for ZGC as well?
+      BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn->_worklist, old);
+    }
   }
 
 }