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.Inductive match_frames: RTL.stackframe -> RTL.stackframe -> Prop :=
  | match_frames_intro: forall res f sp pc rs
        (REACH: reach f pc),
      match_frames (Stackframe res f sp pc rs)
                   (Stackframe res (transf_function f) sp (renum_pc (pnum f) pc) rs).Inductive match_frames: RTL.stackframe -> RTL.stackframe -> Prop :=
  | match_frames_intro: forall res f sp pc rs
        (REACH: reach f pc),
      match_frames (Stackframe res f sp pc rs)
                   (Stackframe res (transf_function f) sp (renum_pc (pnum f) pc) rs).Inductive match_states: RTL.state -> RTL.state -> Prop :=
  | match_regular_states: forall stk f sp pc rs m stk'
        (STACKS: list_forall2 match_frames stk stk')
        (REACH: reach f pc),
      match_states (State stk f sp pc rs m)
                   (State stk' (transf_function f) sp (renum_pc (pnum f) pc) rs m)
  | match_callstates: forall stk f args m stk'
        (STACKS: list_forall2 match_frames stk stk'),
      match_states (Callstate stk f args m)
                   (Callstate stk' (transf_fundef f) args m)
  | match_returnstates: forall stk v m stk'
        (STACKS: list_forall2 match_frames stk stk'),
      match_states (Returnstate stk v m)
                   (Returnstate stk' v m).Inductive match_states: RTL.state -> RTL.state -> Prop :=
  | match_regular_states: forall stk f sp pc rs m stk'
        (STACKS: list_forall2 match_frames stk stk')
        (REACH: reach f pc),
      match_states (State stk f sp pc rs m)
                   (State stk' (transf_function f) sp (renum_pc (pnum f) pc) rs m)
  | match_callstates: forall stk f args m stk'
        (STACKS: list_forall2 match_frames stk stk'),
      match_states (Callstate stk f args m)
                   (Callstate stk' (transf_fundef f) args m)
  | match_returnstates: forall stk v m stk'
        (STACKS: list_forall2 match_frames stk stk'),
      match_states (Returnstate stk v m)
                   (Returnstate stk' v m).Inductive match_states: RTL.state -> RTL.state -> Prop :=
  | match_regular_states: forall stk f sp pc rs m stk'
        (STACKS: list_forall2 match_frames stk stk')
        (REACH: reach f pc),
      match_states (State stk f sp pc rs m)
                   (State stk' (transf_function f) sp (renum_pc (pnum f) pc) rs m)
  | match_callstates: forall stk f args m stk'
        (STACKS: list_forall2 match_frames stk stk'),
      match_states (Callstate stk f args m)
                   (Callstate stk' (transf_fundef f) args m)
  | match_returnstates: forall stk v m stk'
        (STACKS: list_forall2 match_frames stk stk'),
      match_states (Returnstate stk v m)
                   (Returnstate stk' v m).Inductive match_states: RTL.state -> RTL.state -> Prop :=
  | match_regular_states: forall stk f sp pc rs m stk'
        (STACKS: list_forall2 match_frames stk stk')
        (REACH: reach f pc),
      match_states (State stk f sp pc rs m)
                   (State stk' (transf_function f) sp (renum_pc (pnum f) pc) rs m)
  | match_callstates: forall stk f args m stk'
        (STACKS: list_forall2 match_frames stk stk'),
      match_states (Callstate stk f args m)
                   (Callstate stk' (transf_fundef f) args m)
  | match_returnstates: forall stk v m stk'
        (STACKS: list_forall2 match_frames stk stk'),
      match_states (Returnstate stk v m)
                   (Returnstate stk' v m).

Lemma step_simulation: forall S1 t S2, RTL.step ge S1 t S2 -> forall S1', match_states S1 S1' -> exists S2', RTL.step tge S1' t S2' /\ match_states S2 S2'.