;; the same kind (read or write)
(next nil :type (or tn-ref null))
;; the VOP where the reference happens, or NIL temporarily
(vop nil :type (or vop null))
;; the same kind (read or write)
(next nil :type (or tn-ref null))
;; the VOP where the reference happens, or NIL temporarily
(vop nil :type (or vop null))