// control edges.
  for (Node* n : (*graph)->nodes()) {
    if (HasNodeAttr(n->def(), kXlaConnectedToXlaComputationAttrName)) {
      (*graph)->AddControlEdge(n, send_from_host_node);
      n->ClearAttr(kXlaConnectedToXlaComputationAttrName);
    }
    if (HasNodeAttr(n->def(), kXlaConnectedFromXlaComputationAttrName)) {
      (*graph)->AddControlEdge(recv_at_host_node, n);