Definition mod_after_alloc (phi: rmap) (lo hi: Z) (b: block) :=
  proj1_sig (make_rmap (mod_after_alloc' phi lo hi b) (ghost_of phi)
    _
    (mod_after_alloc'_ok phi lo hi b) (ghost_of_approx phi)).

Lemma alloc_dry_updated_on : forall m1 m2 lo hi b loc, alloc m1 lo hi = (m2, b) -> adr_range (b, lo) (hi - lo) loc -> access_at m2 loc Cur=Some Freeable /\ contents_at m2 loc=Undef.