Remark in_norepet_unique:
  forall id g (gl: list (ident * globdef F V)),
  In (id, g) gl -> list_norepet (map fst gl) ->
  exists gl1 gl2, gl = gl1 ++ (id, g) :: gl2 /\ ~In id (map fst gl2).

Theorem find_var_info_iff: forall ge b v, find_var_info ge b = Some v <-> find_def ge b = Some (Gvar v).