Section RENUMBER.
Variable f: PTree.t positive.
Hypothesis f_inj: forall x1 x2 y, f!x1 = Some y -> f!x2 = Some y -> x1 = x2.
End RENUMBER.
Definition pnum (f: function) := postorder (successors_map f) f.(fn_entrypoint).
Definition reach (f: function) (pc: node) := reachable (successors_map f) f.(fn_entrypoint) pc.
Ltac TR_AT :=
match goal with
| [ A: (fn_code _)!_ = Some _ , B: reach _ _ |- _ ] =>
generalize (transf_function_at _ _ _ A B); simpl renum_instr; intros
end.

Lemma reach_succ:
forall f pc i s,
f.(fn_code)!pc = Some i -> In s (successors_instr i) ->
reach f pc -> reach f s.