Ltac do_map_arg :=
match goal with |- ?a = ?b =>
match a with context [map ?x _] =>
match b with context [map ?y _] => replace y with x; auto end end end.

Lemma resource_at_empty: forall phi,
identity phi ->
forall l, phi @ l = NO Share.bot bot_unreadable \/ exists k, exists pds, phi @ l = PURE k pds.