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 necR_res_option:
forall (phi phi' : rmap) (loc : AV.address),
necR phi phi' -> res_option (phi @ loc) = res_option (phi' @ loc).