CristalCaveGem » LustreC

let report = Log.report ~plugin:"salsa" ~verbose_level:Salsa.Log.verbose_level

let fun_types node =

    match node.LT.top_decl_desc with

    | LT.Node nd ->

    | _ ->

      Format.eprintf "%a is not a node@.@?" Printers.pp_decl node;

      assert false

  with Not_found ->

    Format.eprintf "Unable to find type def for function %s@.@?"

      (Corelang.node_name node);

    assert false

let called_node_id m id =

    try List.assoc id m.MT.mcalls (* TODO Xavier: mcalls or minstances ? *)

(******************************************************************)

  let open MT in

  | Var v when Types.is_real_type v.LT.var_type ->

    Vars.singleton v

  | Var _ | Cst _ ->

    Vars.empty

  | Fun (_, args) ->

    List.fold_left

      (fun acc e -> Vars.union acc (get_expr_real_vars e))

  | Array _ | Access _ | Power _ ->

    assert false

  | [] ->

    Vars.empty

  | i :: tl -> (

    let vars_tl = get_read_vars tl in

    | MLocalAssign (_, e) | MStateAssign (_, e) ->

      Vars.union (get_expr_real_vars e) vars_tl

    | MStep (_, _, el) ->

      List.fold_left

        (fun accu e -> Vars.union (get_expr_real_vars e) accu)

        vars_tl el

    | MBranch (e, branches) ->

      List.fold_left

        (fun vars (_, b) -> Vars.union vars (get_read_vars b))

        vars branches

    | MReset _ | MNoReset _ | MSpec _ | MComment _ ->

      Vars.empty)

  | [] ->

    Vars.empty

  | i :: tl -> (

    let vars_tl = get_written_vars tl in

    | MLocalAssign (v, _) | MStateAssign (v, _) ->

      Vars.add v vars_tl

    | MStep (vdl, _, _) ->

      List.fold_left (fun accu v -> Vars.add v accu) vars_tl vdl

    | MBranch (_, branches) ->

      List.fold_left

        (fun vars (_, b) -> Vars.union vars (get_written_vars b))

        vars_tl branches

    | MReset _ | MNoReset _ | MSpec _ | MComment _ ->

      Vars.empty)

  try

    let fresh_id = "toto" in

    (* TODO more meaningful name *)

    report ~level:2 (fun fmt ->

        Format.fprintf fmt "Launching analysis: %s@ "

          (Salsa.Print.printExpression e_salsa));

    let new_e_salsa, e_val =

    report ~level:2 (fun fmt ->

        Format.fprintf fmt " Analysis done: %s@ "

          (Salsa.Print.printExpression new_e_salsa));

    report ~level:2 (fun fmt ->

        Format.fprintf fmt " Computing range progress@ ");

    let expr, expr_range =

      match

        RangesInt.Value.leq old_val e_val, RangesInt.Value.leq e_val old_val

      with

      | true, true ->

        if !debug then

          report ~level:2 (fun fmt ->

              Format.fprintf fmt "No improvement on abstract value %a@ "

                RangesInt.pp_val e_val);

        e_salsa, Some old_val

      | false, true ->

        if !debug then

          report ~level:2 (fun fmt -> Format.fprintf fmt "Improved!@ ");

        new_e_salsa, Some e_val

              "CAREFUL --- new range is worse!. Restoring provided expression@ ");

        e_salsa, Some old_val

      | false, false ->

        report ~level:2 (fun fmt ->

            Format.fprintf fmt

              "Error; new range is not comparable with old end. It may need \

               some investigation!@. ";

            Format.fprintf fmt "old: %a@.new: %a@ " RangesInt.pp_val old_val

              RangesInt.pp_val e_val);

        new_e_salsa, Some e_val

      (* assert false *)

    if !debug then

      report ~level:2 (fun fmt ->

          Format.fprintf fmt

            "  @[<v>old_expr: @[<v 0>%s@ range: %a@]@ new_expr: @[<v 0>%s@ \

             range: %a@]@ @]@ "

            (Salsa.Print.printExpression e_salsa)

            (* MC.pp_val e *)

            RangesInt.pp_val old_val

            (Salsa.Print.printExpression new_e_salsa)

            (* MC.pp_val new_e *)

            RangesInt.pp_val e_val);

  with (* Not_found -> *)

  | Salsa.Epeg_types.EPEGError _ ->

        Format.fprintf fmt

          "BECAUSE OF AN ERROR, Expression %s was not optimized@ "

          (Salsa.Print.printExpression e_salsa)

        (* MC.pp_val e *));

(* Optimize a given expression. It returns the modified expression, a computed

   range and freshly defined variables. *)

let optimize_expr nodename m constEnv printed_vars vars_env ranges formalEnv e :

    MT.value_t * RangesInt.t option * MT.instr_t list * Vars.VarSet.t =

      (* Format.eprintf "optmizing constant expr @ "; *)

      (* the expression is a constant, we optimize it directly if it is a real

         constant *)

      let typ = Typing.type_const Location.dummy_loc cst in

      if Types.is_real_type typ then opt_num_expr m vars_env ranges formalEnv e

      else e, None, [], Vars.empty

    | Var v ->

      if

        (not (Vars.mem v printed_vars))

        && (* TODO xavier: comment recuperer le type de l'expression? Parfois

              e.value_type vaut 'd *)

        (Types.is_real_type e.value_type || Types.is_real_type v.LT.var_type)

      then opt_num_expr m vars_env ranges formalEnv e

      else e, None, [], Vars.empty

    (* Nothing to optimize for expressions containing a single non real variable *)

    (* if Type_predef.is_real_type v.LT.var_type then opt_num_expr ranges

       formalEnv e *)

    | Fun (fun_id, args) ->

      if

        (* necessarily, this is a basic function (ie. + - * / && || mod ... ) *)

        (* if the return type is real then optimize it, otherwise call

           recusrsively on arguments *)

        Types.is_real_type e.value_type

      then opt_num_expr m vars_env ranges formalEnv e

      else

        (* We do not care for computed local ranges. *)

        let args', il, new_locals =

          List.fold_right

            (fun arg (al, il, nl) ->

              let arg', _, arg_il, arg_nl =

                opt_expr m vars_env ranges formalEnv arg

              in

              arg' :: al, arg_il @ il, Vars.union arg_nl nl)

            args ([], [], Vars.empty)

        in

        { e with value_desc = Fun (fun_id, args') }, None, il, new_locals

    | Array _ | Access _ | Power _ ->

      assert false

  and opt_num_expr m vars_env ranges formalEnv e =

    if !debug then

      report ~level:2 (fun fmt ->

          Format.fprintf fmt "Optimizing expression @[<hov>%a@]@ " (MC.pp_val m)

            e);

    (* if !debug then Format.eprintf "Optimizing expression %a with Salsa@ "

       MC.pp_val e; *)

    (* List.iter (fun (l,c) -> Format.eprintf "%s -> %a@ " l Printers.pp_const

       c) constEnv; *)

    (* Format.eprintf "apres deplaige constantes ok%a @." MC.pp_val

       (salsa_expr2value_t vars_env [](\* constEnv *\) e_salsa) ; *)

    (* if !debug then Format.eprintf "Formal env is [%a]@ " FormalEnv.pp

       formalEnv; *)

    (* Format.eprintf "Expression avant et apres substVars.@.Avant %a@."

       MC.pp_val (salsa_expr2value_t vars_env [] e_salsa) ; *)

    let (e_salsa : Salsa.Types.expression), _ =

      Salsa.Rewrite.substVars e_salsa (FormalEnv.to_salsa constEnv formalEnv) 0

      (* TODO: Nasrine, what is this integer value for ? *)

    (* Format.eprintf "Apres %a@." MC.pp_val (salsa_expr2value_t vars_env []

       e_salsa) ; *)

    (* Format.eprintf "avant evalpart: %a@." MC.pp_val (salsa_expr2value_t

       vars_env constEnv e_salsa); *)

    let e_salsa =

      Salsa.Analyzer.evalPartExpr e_salsa

        (Salsa.Analyzer.valEnv2ExprEnv abstractEnv)

        [] (* no blacklisted variables *) []

      (* no arrays *)

    (* Format.eprintf "apres evalpart: %a@." MC.pp_val (salsa_expr2value_t

       vars_env constEnv e_salsa); *)

    (* Checking if we have all necessary information *)

      report ~level:2 (fun fmt ->

          Format.fprintf fmt

            "Warning: unbounded free vars (%a) in expression %a. We do not \

             optimize it.@ "

            Vars.pp

            (Vars.fold

               (fun v accu ->

                 let v' =

                   {

                     v with

                     LT.var_id = nodename.LT.node_id ^ "." ^ v.LT.var_id;

                   }

                 in

                 Vars.add v' accu)

               free_vars Vars.empty)

            (MC.pp_val m)

            (salsa_expr2value_t vars_env constEnv e_salsa));

      if !debug then

        report ~level:2 (fun fmt ->

            Format.fprintf fmt "Some free vars, not optimizing@ ");

      if !debug then

        report ~level:3 (fun fmt ->

            Format.fprintf fmt "  ranges: %a@ " RangesInt.pp ranges);

      (* if !debug then Log.report ~level:2 (fun fmt -> Format.fprintf fmt

         "Formal env was @[<v 0>%a@]@ " FormalEnv.pp formalEnv); *)

      let new_e =

        try salsa_expr2value_t vars_env constEnv e_salsa

        with Not_found -> assert false

      in

      new_e, None, [], Vars.empty)

        report ~level:3 (fun fmt ->

            Format.fprintf fmt

              "@[<v 2>Analyzing expression %a@  with ranges: @[<v>%a@ @]@ @]@ "

              (C_backend_common.pp_c_val m ""

                 (C_backend_common.pp_c_var_read m))

              (salsa_expr2value_t vars_env constEnv e_salsa)

              (Utils.fprintf_list ~sep:",@ " (fun fmt (l, r) ->

                   Format.fprintf fmt "%s -> %a" l FloatIntSalsa.pp r))

              abstractEnv);

      (* Slicing expression *)

      let e_salsa, seq =

        try

          Salsa.Rewrite.sliceExpr e_salsa 0

            (Salsa.Types.Nop (Salsa.Types.Lab 0))

        with _ ->

          Format.eprintf "Issues rewriting express %s@.@?"

            (Salsa.Print.printExpression e_salsa);

          assert false

      in

      let def_tmps = Salsa.Utils.flatten_seq seq [] in

      (* Registering tmp ids in vars_env *)

      let vars_env', new_local_vars =

        List.fold_left

          (fun (vs, vars) (id, _) ->

            let vdecl =

              Corelang.mk_fresh_var (nodename.node_id, [])

                (* TODO check that the empty env is ok. One may need to build or

                   access to the current env *)

                Location.dummy_loc e.MT.value_type (Clocks.new_var true)

            in

            let vs' = VarEnv.add id { vdecl; is_local = true } vs in

            let vars' = Vars.add vdecl vars in

            vs', vars')

          (vars_env, Vars.empty) def_tmps

      in

      (* Debug *)

      if !debug then

        report ~level:3 (fun fmt ->

            Format.fprintf fmt "List of slices: @[<v 0>%a@]@ "

              (Utils.fprintf_list ~sep:"@ " (fun fmt (id, e_id) ->

                   Format.fprintf fmt "(%s,%a) -> %a" id Printers.pp_var

                     (get_var vars_env' id).vdecl

                     (C_backend_common.pp_c_val m ""

                        (C_backend_common.pp_c_var_read m))

                     (salsa_expr2value_t vars_env' constEnv e_id)))

              def_tmps;

            Format.fprintf fmt "Sliced expression: %a@ "

              (C_backend_common.pp_c_val m ""

                 (C_backend_common.pp_c_var_read m))

              (salsa_expr2value_t vars_env' constEnv e_salsa));

      (* Debug *)

      (* Optimize def tmp, and build the associated instructions. Update the

         abstract Env with computed ranges *)

      if !debug && List.length def_tmps >= 1 then

        report ~level:3 (fun fmt ->

            Format.fprintf fmt "@[<v 3>Optimizing sliced sub-expressions@ ");

      let rev_def_tmp_instrs, ranges =

        List.fold_left

          (fun (accu_instrs, ranges) (id, e_id) ->

            (* Format.eprintf "Cleaning/Optimizing %s@." id; *)

            let e_id', e_range =

              (*Salsa.MainEPEG.transformExpression id e_id abstractEnv*)

              opt_num_expr_sliced ranges e_id

            in

            let new_e_id' =

              try salsa_expr2value_t vars_env' constEnv e_id'

              with Not_found -> assert false

            in

            let vdecl = (get_var vars_env' id).vdecl in

            let new_local_assign =

              (* let expr = salsa_expr2value_t vars_env' constEnv e_id' in *)

              MT.MLocalAssign (vdecl, new_e_id')

            in

            let new_local_assign =

              {

                MT.instr_desc = new_local_assign;

                MT.lustre_eq =

                  None

                  (* could be Corelang.mkeq Location.dummy_loc

                     ([vdecl.LT.var_id], e_id) provided it is converted as

                     Lustre expression rather than a Machine code value *);

              }

            in

            let new_ranges =

              match e_range with

              | None ->

                ranges

              | Some e_range ->

                RangesInt.add_def ranges id e_range

            in

            new_local_assign :: accu_instrs, new_ranges)

          ([], ranges) def_tmps

      in

      if !debug && List.length def_tmps >= 1 then

        report ~level:3 (fun fmt -> Format.fprintf fmt "@]@ ");

      (* Format.eprintf "Optimizing main expression %s@.AbstractEnv is %a"

         (Salsa.Print.printExpression e_salsa) RangesInt.pp ranges; *)

      let expr_salsa, expr_range = opt_num_expr_sliced ranges e_salsa in

      let expr =

        try salsa_expr2value_t vars_env' constEnv expr_salsa

        with Not_found -> assert false

      in

      expr, expr_range, List.rev rev_def_tmp_instrs, new_local_vars

      (* ???? Bout de code dans unstable lors du merge avec salsa ? ====

         let new_e = try salsa_expr2value_t vars_env' constEnv new_e_salsa with

         Not_found -> assert false in if !debug then Log.report ~level:2 (fun

         fmt -> let old_range = Salsa.Analyzer.evalExpr e_salsa abstractEnv []

         in match RangesInt.Value.leq old_range e_val, RangesInt.Value.leq e_val

         old_range with | true, true -> Format.fprintf fmt "No improvement on

         abstract value %a@ " RangesInt.pp_val e_val | true, false -> (

         Format.fprintf fmt "Improved!"; Format.fprintf fmt " @[<v>old_expr:

         @[<v 0>%a@ range: %a@]@ new_expr: @[<v 0>%a@ range: %a@]@ @]@ "

         (MC.pp_val m) e RangesInt.pp_val (Salsa.Analyzer.evalExpr e_salsa

         abstractEnv []) (MC.pp_val m) new_e RangesInt.pp_val e_val ) | false,

         true -> Format.eprintf "Error; new range is worse!@.@?"; assert false |

         false, false -> Format.eprintf "Error; new range is not comparabe with

         old end. This should not happen!@.@?"; assert false ); new_e, Some

         e_val, List.rev rev_def_tmp_instrs with (* Not_found -> *) |

         Salsa.Epeg_types.EPEGError _ -> ( Log.report ~level:2 (fun fmt ->

         Format.fprintf fmt "BECAUSE OF AN ERROR, Expression %a was not

         optimized@ " (MC.pp_val m) e); e, None, [] ) >>>>>>> unstable *))

  opt_expr m vars_env ranges formalEnv e

let assign_vars nodename m constEnv vars_env printed_vars ranges formalEnv

    vars_to_print =

  let ordered_vars =

      (FormalEnv.get_sort_fun formalEnv)

      (Vars.elements vars_to_print)

  if !debug then

    report ~level:4 (fun fmt ->

        Format.fprintf fmt "Printing vars in the following order: [%a]@ "

          (Utils.fprintf_list ~sep:", " Printers.pp_var)

          ordered_vars);

  List.fold_right

    (fun v (accu_instr, accu_ranges, accu_new_locals) ->

      if !debug then

        report ~level:4 (fun fmt ->

            Format.fprintf fmt "Printing assign for variable %s@ " v.LT.var_id);

        (* Obtaining unfold expression of v in formalEnv *)

        let v_def = FormalEnv.get_def formalEnv v in

        let e, r, il, new_v_locals =

          optimize_expr nodename m constEnv printed_vars vars_env ranges

            formalEnv v_def

        in

        let instr_desc =

          if

            try (get_var vars_env v.LT.var_id).is_local

            with Not_found -> assert false

          then MT.MLocalAssign (v, e)

          else MT.MStateAssign (v, e)

        in

        ( il @ Corelang.mkinstr instr_desc :: accu_instr,

          (match r with

          | None ->

            ranges

          | Some v_r ->

            RangesInt.add_def ranges v.LT.var_id v_r),

          Vars.union accu_new_locals new_v_locals )

      with FormalEnv.NoDefinition _ ->

        if

          (* It should not happen with C backend, but may happen with Lustre

             backend *)

          !Options.output = "lustre"

        then accu_instr, ranges, Vars.empty

        else (

          Format.eprintf "@?";

          assert false))

    ordered_vars ([], ranges, Vars.empty)

let rec rewrite_instrs nodename m constEnv vars_env m instrs ranges formalEnv

    printed_vars vars_to_print =

  | [] ->

    (* End of instruction list: we produce the definition of each variable that

       appears in vars_to_print. Each of them should be defined in formalEnv *)

    (* if !debug then Format.eprintf "Producing definitions %a@ " Vars.pp

       vars_to_print; *)

    let instrs, ranges', new_expr_locals =

      assign_vars printed_vars ranges formalEnv vars_to_print

    in

    ( instrs,

      ranges',

      formalEnv,

      Vars.union printed_vars vars_to_print,

      (* We should have printed all required vars *)

      [],

      (* No more vars to be printed *)

      Vars.empty )

  | hd_instr :: tl_instrs ->

    (* We reformulate hd_instr, producing or not a fresh instruction, updating

       formalEnv, possibly ranges and vars_to_print *)

    let hd_instrs, ranges, formalEnv, printed_vars, vars_to_print, hd_new_locals

        =

      match Corelang.get_instr_desc hd_instr with

      | MT.MLocalAssign (vd, vt)

        when Types.is_real_type vd.LT.var_type

             && not (Vars.mem vd vars_to_print) ->

        (* LocalAssign are injected into formalEnv *)

        (* if !debug then Format.eprintf "Registering local assign %a@ "

           MC.pp_instr hd_instr; *)

        (* if !debug then Format.eprintf "%a@ " MC.pp_instr hd_instr; *)

        let formalEnv' = formal_env_def formalEnv vd vt in

        (* formelEnv updated with vd = vt *)

        ( [],

          (* no instr generated *)

          ranges,

          (* no new range computed *)

          formalEnv',

          printed_vars,

          (* no new printed vars *)

          vars_to_print,

          (* no more or less variables to print *)

          Vars.empty )

      (* no new locals *)

      | MT.MLocalAssign (vd, vt)

        when Types.is_real_type vd.LT.var_type && Vars.mem vd vars_to_print ->

        (* if !debug then Format.eprintf "Registering and producing state assign

           %a@ " MC.pp_instr hd_instr; *)

        (* if !debug then Format.eprintf "Registering and producing state assign

           %a@ " MC.pp_instr hd_instr; *)

        (* if !debug then ( *)

        (*   Format.eprintf "%a@ " MC.pp_instr hd_instr; *)

        (* Format.eprintf "Selected var %a: producing expression@ "

           Printers.pp_var vd; *)

        (* ); *)

        let formalEnv' = formal_env_def formalEnv vd vt in

        (* formelEnv updated with vd = vt *)

        let instrs', ranges', expr_new_locals =

          (* printing vd = optimized vt *)

          assign_vars printed_vars ranges formalEnv' (Vars.singleton vd)

        in

        ( instrs',

          ranges',

          (* no new range computed *)

          formalEnv',

          (* formelEnv already updated *)

          Vars.add vd printed_vars,

          (* adding vd to new printed vars *)

          Vars.remove vd vars_to_print,

          (* removed vd from variables to print *)

          expr_new_locals )

      (* adding sliced vardecl to the list *)

      | MT.MStateAssign (vd, vt)

        when Types.is_real_type vd.LT.var_type

             (* && Vars.mem vd vars_to_print *) ->

        (* StateAssign are produced since they are required by the function. We

           still keep their definition in the formalEnv in case it can optimize

           later outputs. vd is removed from remaining vars_to_print *)

        (* if !debug then Format.eprintf "Registering and producing state assign

           %a@ " MC.pp_instr hd_instr; *)

        (* if !debug then ( *)

        (*   Format.eprintf "%a@ " MC.pp_instr hd_instr; *)

        (* Format.eprintf "State assign %a: producing expression@ "

           Printers.pp_var vd; *)

        (* ); *)

        let formalEnv' = formal_env_def formalEnv vd vt in

        (* formelEnv updated with vd = vt *)

        let instrs', ranges', expr_new_locals =

          (* printing vd = optimized vt *)

          assign_vars printed_vars ranges formalEnv' (Vars.singleton vd)

        in

        ( instrs',

          ranges',

          (* no new range computed *)

          formalEnv,

          (* formelEnv already updated *)

          Vars.add vd printed_vars,

          (* adding vd to new printed vars *)

          Vars.remove vd vars_to_print,

          (* removed vd from variables to print *)

          expr_new_locals )

      (* adding sliced vardecl to the list *)

      | MT.MLocalAssign (vd, vt) | MT.MStateAssign (vd, vt) ->

        (* Format.eprintf "other assign %a@." MC.pp_instr hd_instr; *)

        (* We have to produce the instruction. But we may have to produce as

           well its dependencies *)

        let required_vars = get_expr_real_vars vt in

        let required_vars = Vars.diff required_vars printed_vars in

        (* remove already produced variables *)

        (* Format.eprintf "Required vars: %a@." Vars.pp required_vars; *)

        let required_vars =

          Vars.diff required_vars (Vars.of_list m.MT.mmemory)

        in

        let prefix_instr, ranges, new_expr_dep_locals =

          assign_vars printed_vars ranges formalEnv required_vars

        in

        let vt', _, il, expr_new_locals =

          optimize_expr nodename m constEnv

            (Vars.union required_vars printed_vars)

            vars_env ranges formalEnv vt

        in

        let new_instr =

          match Corelang.get_instr_desc hd_instr with

          | MT.MLocalAssign _ ->

            Corelang.update_instr_desc hd_instr (MT.MLocalAssign (vd, vt'))

          | _ ->

            Corelang.update_instr_desc hd_instr (MT.MStateAssign (vd, vt'))

        in

        let written_vars = Vars.add vd required_vars in

        ( prefix_instr @ il @ [ new_instr ],

          ranges,

          (* no new range computed *)

          formalEnv,

          (* formelEnv untouched *)

          Vars.union written_vars printed_vars,

          (* adding vd + dependencies to new printed vars *)

          Vars.diff vars_to_print written_vars,

          (* removed vd + dependencies from variables to print *)

          Vars.union new_expr_dep_locals expr_new_locals )

      | MT.MStep (vdl, id, vtl) ->

        (* Format.eprintf "step@."; *)

        (* if !debug then Format.eprintf "Call to a node %a@ " MC.pp_instr

           hd_instr; *)

        (* Call of an external function. Input expressions have to be optimized,

           their free variables produced. A fresh range has to be computed for

           each output variable in vdl. Output of the function call are removed

           from vars to be printed *)

        let node = called_node_id m id in

        let node_id = Corelang.node_name node in

        let tin, tout =

          (* special care for arrow *)

          if node_id = "_arrow" then

            match vdl with

            | [ v ] ->

              let t = v.LT.var_type in

              [ t; t ], [ t ]

            | _ ->

              assert false (* should not happen *)

          else fun_types node

        in

        (* if !debug then Format.eprintf "@[<v 2>... optimizing arguments@ "; *)

        let vtl', vtl_ranges, il, args_new_locals =

          List.fold_right2

            (fun e typ_e (exprl, range_l, il_l, new_locals) ->

              if Types.is_real_type typ_e then

                let e', r', il, new_expr_locals =

                  optimize_expr nodename m constEnv printed_vars vars_env ranges

                    formalEnv e

                in

                ( e' :: exprl,

                  r' :: range_l,

                  il @ il_l,

                  Vars.union new_locals new_expr_locals )

              else e :: exprl, None :: range_l, il_l, new_locals)

            vtl tin ([], [], [], Vars.empty)

        in

        (* if !debug then Format.eprintf "... done@ @]@ "; *)

        (* let required_vars =  *)

        (*   List.fold_left2  *)

        (*     (fun accu e typ_e ->  *)

        (* 	 if Types.is_real_type typ_e then *)

        (* 	   Vars.union accu (get_expr_real_vars e)  *)

        (* 	 else (\* we do not consider non real expressions *\) *)

        (* 	   accu *)

        (*     ) *)

        (*     Vars.empty  *)

        (*     vtl' tin *)

        (* in *)

        (* if !debug then Format.eprintf "Required vars: [%a]@ Printed vars:

           [%a]@ Remaining required vars: [%a]@ " *)

        (*   Vars.pp required_vars  *)

        (*   Vars.pp printed_vars *)

        (*   Vars.pp (Vars.diff required_vars printed_vars) *)

        (* ; *)

        (* let required_vars = Vars.diff required_vars printed_vars in (\* remove *)

        (* 								  already *)

        (* 								  produced *)

        (* 								  variables *\) *)

        (* let written_vars = Vars.union required_vars (Vars.of_list vdl) in *)

        (* let instrs', ranges' = assign_vars (Vars.union written_vars

           printed_vars) ranges formalEnv required_vars in *)

        (* instrs' @ [Corelang.update_instr_desc hd_instr

           (MT.MStep(vdl,id,vtl'))], (* New instrs *) *)

        let written_vars = Vars.of_list vdl in

        ( il @ [ Corelang.update_instr_desc hd_instr (MT.MStep (vdl, id, vtl')) ],

          (* New instrs *)

          RangesInt.add_call ranges vdl id vtl_ranges,

          (* add information bounding each vdl var *)

          formalEnv,

          Vars.union written_vars printed_vars,

          (* adding vdl to new printed vars *)

          Vars.diff vars_to_print written_vars,

          args_new_locals )

      | MT.MBranch (vt, branches) ->

        (* Required variables to compute vt are introduced. Then each branch is

           refactored specifically *)

        (* if !debug then Format.eprintf "Branching %a@ " MC.pp_instr hd_instr; *)

        let required_vars = get_expr_real_vars vt in

        let required_vars = Vars.diff required_vars printed_vars in

        (* remove already produced variables *)

        let vt', _, prefix_instr, prefix_new_locals =

          optimize_expr nodename m constEnv printed_vars vars_env ranges

            formalEnv vt

        in

        let new_locals = prefix_new_locals in

        (* let prefix_instr, ranges = *)

        (* assign_vars (Vars.union required_vars printed_vars) ranges formalEnv

           required_vars in *)

        let printed_vars = Vars.union printed_vars required_vars in

        let read_vars_tl = get_read_vars tl_instrs in

        (* if !debug then Format.eprintf "@[<v 2>Dealing with branches@ "; *)

        let branches', written_vars, merged_ranges, new_locals =

          List.fold_right

            (fun (b_l, b_instrs)

                 (new_branches, written_vars, merged_ranges, new_locals) ->

              let b_write_vars = get_written_vars b_instrs in

              let b_vars_to_print =

                Vars.inter b_write_vars (Vars.union read_vars_tl vars_to_print)

              in

              let b_fe = formalEnv in

              (* because of side effect data, we copy it for each branch *)

              let ( b_instrs',

                    b_ranges,

                    b_formalEnv,

                    b_printed,

                    b_vars,

                    b_new_locals ) =

                rewrite_instrs nodename m constEnv vars_env m b_instrs ranges

                  b_fe printed_vars b_vars_to_print

              in

              (* b_vars should be empty *)

              let _ = if b_vars != [] then assert false in

              (* Producing the refactored branch *)

              ( (b_l, b_instrs') :: new_branches,

                Vars.union b_printed written_vars,

                (* They should coincides. We use union instead of inter to ease

                   the bootstrap *)

                RangesInt.merge merged_ranges b_ranges,

                Vars.union new_locals b_new_locals ))

            branches

            ([], required_vars, ranges, new_locals)

        in

        (* if !debug then Format.eprintf "dealing with branches done@ @]@ "; *)

        ( prefix_instr

          @ [

              Corelang.update_instr_desc hd_instr (MT.MBranch (vt', branches'));

            ],

          merged_ranges,

          (* Only step functions call within branches may have produced new

             ranges. We merge this data by computing the join per variable *)

          formalEnv,

          (* Thanks to the computation of var_to_print in each branch, no new

             definition should have been computed without being already printed *)

          Vars.union written_vars printed_vars,

          Vars.diff vars_to_print written_vars

          (* We remove vars that have been produced within branches *),

          new_locals )

      | MT.MReset _ | MT.MNoReset _ | MT.MSpec _ | MT.MComment _ ->

        (* if !debug then Format.eprintf "Untouched %a (non real)@ " MC.pp_instr

           hd_instr; *)

        (* Untouched instruction *)

        ( [ hd_instr ],

          (* unmodified instr *)

          ranges,

          (* no new range computed *)

          formalEnv,

          (* no formelEnv update *)

          printed_vars,

          vars_to_print,

          (* no more or less variables to print *)

          Vars.empty )

      (* no new slides vars *)

    in

    let tl_instrs, ranges, formalEnv, printed_vars, vars_to_print, tl_new_locals

        =

      rewrite_instrs nodename m constEnv vars_env m tl_instrs ranges formalEnv

        printed_vars vars_to_print

    in

    ( hd_instrs @ tl_instrs,

      ranges,

      formalEnv,

      printed_vars,

      vars_to_print,

      Vars.union hd_new_locals tl_new_locals )

let salsaStep constEnv m s =

  let ranges =

    RangesInt.empty

    (* empty for the moment, should be build from machine annotations or

       externally provided information *)