Definition atomic_loc sh p R := !!(field_compatible tatomic [] p) &&
(EX lock : val, field_at sh tatomic [StructField _lock] lock p * lock_inv sh lock (A_inv p lock R)).

Lemma atomic_loc_super_non_expansive : forall n sh p R,
compcert_rmaps.RML.R.approx n (atomic_loc sh p R) =
compcert_rmaps.RML.R.approx n (atomic_loc sh p (fun v => compcert_rmaps.RML.R.approx n (R v))).