(*TODO: Move to ev_semantics*)
    Definition in_free_list (b : block) ofs xs :=
      exists x, List.In x xs /\
           let '(b', lo, hi) := x in
           b = b' /\
           (lo <= ofs < hi)%Z.

Lemma bareStep_det: forall U tr tp m U' tr' tp' m' U'' tr'' tp'' m'' (Hstep: MachStep (U, tr, tp) m (U', tr', tp') m') (Hstep': MachStep (U, tr, tp) m (U'', tr'', tp'') m''), U' = U'' /\ tr' = tr'' /\ tp' = tp'' /\ m' = m''.