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_YES'':
forall phi phi' loc sh k,
necR phi phi' ->
((exists pp, phi@loc = YES sh k pp) <->
(exists pp, phi'@loc = YES sh k pp)).