*** old/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.graph/src/org/graalvm/compiler/graph/CachedGraph.java	Fri Jul  7 09:29:58 2017
--- new/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.graph/src/org/graalvm/compiler/graph/CachedGraph.java	Fri Jul  7 09:29:58 2017

*** 60,69 ****
--- 60,71 ----
      }
  
      @SuppressWarnings("unchecked")
      public G getMutableCopy(Consumer<UnmodifiableEconomicMap<Node, Node>> duplicationMapCallback) {
          if (!hasMutableCopy()) {
              mutableCopy = (G) readonlyCopy.copy(duplicationMapCallback);
+             // Sharing the debug context with the copy is safe since both graphs are
+             // only used in the current thread.
+             mutableCopy = (G) readonlyCopy.copy(duplicationMapCallback, readonlyCopy.getDebug());
          }
          return mutableCopy;
      }
  }