CristalCaveGem » LustreC

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

(*                                                                  *)

(*  The LustreC compiler toolset   /  The LustreC Development Team  *)

(*  Copyright 2012 -    --   ONERA - CNRS - INPT - LIFL             *)

(*                                                                  *)

(*  LustreC is free software, distributed WITHOUT ANY WARRANTY      *)

(*  under the terms of the GNU Lesser General Public License        *)

(*  version 2.1.                                                    *)

(*                                                                  *) 

(*  This file was originally from the Prelude compiler              *)

(*                                                                  *) 

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

(** Main clock-calculus module. Based on type inference algorithms with

  destructive unification. Uses a bit of subtyping for periodic clocks. *)

(* Though it shares similarities with the typing module, no code

    is shared.  Simple environments, very limited identifier scoping, no

    identifier redefinition allowed. *)

open Utils

open LustreSpec

open Corelang

open Clocks

open Format

let loc_of_cond loc_containing id =

  let pos_start =

    {loc_containing.Location.loc_end with 

     Lexing.pos_cnum=loc_containing.Location.loc_end.Lexing.pos_cnum-(String.length id)}

  in

  {Location.loc_start = pos_start;

   Location.loc_end = loc_containing.Location.loc_end}

(** [occurs cvar ck] returns true if the clock variable [cvar] occurs in

    clock [ck]. False otherwise. *)

let rec occurs cvar ck =

  let ck = repr ck in

  match ck.cdesc with

  | Carrow (ck1, ck2) ->

      (occurs cvar ck1) || (occurs cvar ck2)

  | Ctuple ckl ->

      List.exists (occurs cvar) ckl

  | Con (ck',_,_) -> occurs cvar ck'

  | Pck_up (ck',_) -> occurs cvar ck'

  | Pck_down (ck',_) -> occurs cvar ck'

  | Pck_phase (ck',_) -> occurs cvar ck'

  | Cvar _ -> ck=cvar

  | Cunivar _ | Pck_const (_,_) -> false

  | Clink ck' -> occurs cvar ck'

  | Ccarrying (_,ck') -> occurs cvar ck'

(* Clocks generalization *)

let rec generalize_carrier cr =

  match cr.carrier_desc with

  | Carry_const _

  | Carry_name ->

      if cr.carrier_scoped then

        raise (Scope_carrier cr);

      cr.carrier_desc <- Carry_var

  | Carry_var -> ()

  | Carry_link cr' -> generalize_carrier cr'

(** Promote monomorphic clock variables to polymorphic clock variables. *)

(* Generalize by side-effects *)

let rec generalize ck =

    match ck.cdesc with

    | Carrow (ck1,ck2) ->

        generalize ck1; generalize ck2

    | Ctuple clist ->

        List.iter generalize clist

    | Con (ck',cr,_) -> generalize ck'; generalize_carrier cr

    | Cvar cset ->

        if ck.cscoped then

          raise (Scope_clock ck);

        ck.cdesc <- Cunivar cset

    | Pck_up (ck',_) -> generalize ck'

    | Pck_down (ck',_) -> generalize ck'

    | Pck_phase (ck',_) -> generalize ck'

    | Pck_const (_,_) | Cunivar _ -> ()

    | Clink ck' ->

        generalize ck'

    | Ccarrying (cr,ck') ->

        generalize_carrier cr; generalize ck'

let try_generalize ck_node loc =

  try 

    generalize ck_node

  with (Scope_carrier cr) ->

    raise (Error (loc, Carrier_extrusion (ck_node, cr)))

  | (Scope_clock ck) ->

    raise (Error (loc, Clock_extrusion (ck_node, ck)))

(* Clocks instanciation *)

let instantiate_carrier cr inst_cr_vars =

  let cr = carrier_repr cr in

  match cr.carrier_desc with

  | Carry_const _

  | Carry_name -> cr

  | Carry_link _ ->

      failwith "Internal error"

  | Carry_var ->

      try

        List.assoc cr.carrier_id !inst_cr_vars

      with Not_found ->            

        let cr_var = new_carrier Carry_name true in

        inst_cr_vars := (cr.carrier_id,cr_var)::!inst_cr_vars;

        cr_var

(** Downgrade polymorphic clock variables to monomorphic clock variables *)

(* inst_ck_vars ensures that a polymorphic variable is instanciated with

   the same monomorphic variable if it occurs several times in the same

   type. inst_cr_vars is the same for carriers. *)

let rec instantiate inst_ck_vars inst_cr_vars ck =

  match ck.cdesc with

  | Carrow (ck1,ck2) ->

      {ck with cdesc =

       Carrow ((instantiate inst_ck_vars inst_cr_vars ck1),

               (instantiate inst_ck_vars inst_cr_vars ck2))}

  | Ctuple cklist ->

      {ck with cdesc = Ctuple 

         (List.map (instantiate inst_ck_vars inst_cr_vars) cklist)}

  | Con (ck',c,l) ->

      let c' = instantiate_carrier c inst_cr_vars in

      {ck with cdesc = Con ((instantiate inst_ck_vars inst_cr_vars ck'),c',l)}

  | Cvar _ | Pck_const (_,_) -> ck

  | Pck_up (ck',k) ->

      {ck with cdesc = Pck_up ((instantiate inst_ck_vars inst_cr_vars ck'),k)}

  | Pck_down (ck',k) ->

      {ck with cdesc = Pck_down ((instantiate inst_ck_vars inst_cr_vars ck'),k)}

  | Pck_phase (ck',q) ->

      {ck with cdesc = Pck_phase ((instantiate inst_ck_vars inst_cr_vars ck'),q)}

  | Clink ck' ->

      {ck with cdesc = Clink (instantiate inst_ck_vars inst_cr_vars ck')}

  | Ccarrying (cr,ck') ->

      let cr' = instantiate_carrier cr inst_cr_vars in

        {ck with cdesc =

         Ccarrying (cr',instantiate inst_ck_vars inst_cr_vars ck')}

  | Cunivar cset ->

      try

        List.assoc ck.cid !inst_ck_vars

      with Not_found ->

        let var = new_ck (Cvar cset) true in

	inst_ck_vars := (ck.cid, var)::!inst_ck_vars;

	var

(** [subsume pck1 cset1] subsumes clock [pck1] by clock subset

    [cset1]. The clock constraint is actually recursively transfered to

    the clock variable appearing in [pck1] *)

let subsume pck1 cset1 =

  let rec aux pck cset =

    match cset with

    | CSet_all ->

        ()

    | CSet_pck (k,(a,b)) ->

        match pck.cdesc with

        | Cvar cset' ->

            pck.cdesc <- Cvar (intersect cset' cset)

        | Pck_up (pck',k') ->

            let rat = if a=0 then (0,1) else (a,b*k') in

            aux pck' (CSet_pck ((k*k'),rat))

        | Pck_down (pck',k') ->

            let k''=k/(gcd k k') in

            aux pck' (CSet_pck (k'',(a*k',b)))

        | Pck_phase (pck',(a',b')) ->

            let (a'',b'')= max_rat (sum_rat (a,b) (-a',b')) (0,1) in

            aux pck' (CSet_pck (k, (a'',b'')))

        | Pck_const (n,(a',b')) ->

            if n mod k <> 0 || (max_rat (a,b) (a',b')) <> (a',b') then

              raise (Subsume (pck1, cset1))

        | Clink pck' ->

            aux pck' cset

        | Cunivar _ -> ()

        | Ccarrying (_,ck') ->

            aux ck' cset

        | _ -> raise (Subsume (pck1, cset1))

  in

  aux pck1 cset1

let rec update_scope_carrier scoped cr =

  if (not scoped) then

    begin

      cr.carrier_scoped <- scoped;

      match cr.carrier_desc with

	| Carry_const _ | Carry_name | Carry_var -> ()

      | Carry_link cr' -> update_scope_carrier scoped cr'

    end

let rec update_scope scoped ck =

  if (not scoped) then

    begin

      ck.cscoped <- scoped;

      match ck.cdesc with

      | Carrow (ck1,ck2) ->

          update_scope scoped ck1; update_scope scoped ck2

      | Ctuple clist ->

          List.iter (update_scope scoped) clist

      | Con (ck',cr,_) -> update_scope scoped ck'(*; update_scope_carrier scoped cr*)

      | Cvar cset ->

          ck.cdesc <- Cvar cset

      | Pck_up (ck',_) -> update_scope scoped ck'

      | Pck_down (ck',_) -> update_scope scoped ck'

      | Pck_phase (ck',_) -> update_scope scoped ck'

      | Pck_const (_,_) | Cunivar _ -> ()

      | Clink ck' ->

          update_scope scoped ck'

      | Ccarrying (cr,ck') ->

          update_scope_carrier scoped cr; update_scope scoped ck'

    end

(* Unifies two static pclocks. *)

let unify_static_pck ck1 ck2 =

  if (period ck1 <> period ck2) || (phase ck1 <> phase ck2) then

    raise (Unify (ck1,ck2))

(* Unifies two clock carriers *)

let unify_carrier cr1 cr2 =

  let cr1 = carrier_repr cr1 in

  let cr2 = carrier_repr cr2 in

  if cr1==cr2 then ()

  else

    match cr1.carrier_desc, cr2.carrier_desc with

    | Carry_const id1, Carry_const id2 ->

      if id1 <> id2 then raise (Mismatch (cr1, cr2))

    | Carry_const _, Carry_name ->

      begin

	cr2.carrier_desc <- Carry_link cr1;

	update_scope_carrier cr2.carrier_scoped cr1

      end

    | Carry_name, Carry_const _ ->

      begin

        cr1.carrier_desc <- Carry_link cr2;

        update_scope_carrier cr1.carrier_scoped cr2

      end

    | Carry_name, Carry_name ->

      if cr1.carrier_id < cr2.carrier_id then

        begin

          cr2.carrier_desc <- Carry_link cr1;

          update_scope_carrier cr2.carrier_scoped cr1

        end

      else

        begin

          cr1.carrier_desc <- Carry_link cr2;

          update_scope_carrier cr1.carrier_scoped cr2

        end

    | _,_ -> assert false

(* Semi-unifies two clock carriers *)

let semi_unify_carrier cr1 cr2 =

  let cr1 = carrier_repr cr1 in

  let cr2 = carrier_repr cr2 in

  if cr1==cr2 then ()

  else

    match cr1.carrier_desc, cr2.carrier_desc with

    | Carry_const id1, Carry_const id2 ->

      if id1 <> id2 then raise (Mismatch (cr1, cr2))

    | Carry_const _, Carry_name ->

      begin

	cr2.carrier_desc <- Carry_link cr1;

	update_scope_carrier cr2.carrier_scoped cr1

      end

    | Carry_name, Carry_const _ -> raise (Mismatch (cr1, cr2))

    | Carry_name, Carry_name ->

      if cr1.carrier_id < cr2.carrier_id then

        begin

          cr2.carrier_desc <- Carry_link cr1;

          update_scope_carrier cr2.carrier_scoped cr1

        end

      else

        begin

          cr1.carrier_desc <- Carry_link cr2;

          update_scope_carrier cr1.carrier_scoped cr2

        end

    | _,_ -> assert false

(** [unify ck1 ck2] unifies clocks [ck1] and [ck2]. Raises [Unify

    (ck1,ck2)] if the clocks are not unifiable.*)

let rec unify ck1 ck2 =

  let ck1 = repr ck1 in

  let ck2 = repr ck2 in

  if ck1==ck2 then

    ()

  else

    let left_const = is_concrete_pck ck1 in

    let right_const = is_concrete_pck ck2 in

    if left_const && right_const then

      unify_static_pck ck1 ck2

    else

      match ck1.cdesc,ck2.cdesc with

      | Cvar cset1,Cvar cset2->

          if ck1.cid < ck2.cid then

            begin

              ck2.cdesc <- Clink (simplify ck1);

              update_scope ck2.cscoped ck1;

              subsume ck1 cset2

            end

          else

            begin

              ck1.cdesc <- Clink (simplify ck2);

              update_scope ck1.cscoped ck2;

              subsume ck2 cset1

            end

      | Cvar cset, Pck_up (_,_) | Cvar cset, Pck_down (_,_)

      | Cvar cset, Pck_phase (_,_) | Cvar cset, Pck_const (_,_) ->

          if (occurs ck1 ck2) then

            begin

              if (simplify ck2 = ck1) then

                ck2.cdesc <- Clink (simplify ck1)

              else

                raise (Unify (ck1,ck2));

              end

          else

            begin

              ck1.cdesc <- Clink (simplify ck2);

              subsume ck2 cset

            end

      | Pck_up (_,_), Cvar cset | Pck_down (_,_), Cvar cset

      | Pck_phase (_,_), Cvar cset | Pck_const (_,_), Cvar cset ->

            if (occurs ck2 ck1) then

              begin

                if ((simplify ck1) = ck2) then

                  ck1.cdesc <- Clink (simplify ck2)

                else

                  raise (Unify (ck1,ck2));

              end

            else

              begin

                ck2.cdesc <- Clink (simplify ck1);

                subsume ck1 cset

              end

      | (Cvar cset,_) when (not (occurs ck1 ck2)) ->

          subsume ck2 cset;

          update_scope ck1.cscoped ck2;

          ck1.cdesc <- Clink (simplify ck2)

      | (_, (Cvar cset)) when (not (occurs ck2 ck1)) ->

          subsume ck1 cset;

          update_scope ck2.cscoped ck1;

          ck2.cdesc <- Clink (simplify ck1)

      | Ccarrying (cr1,ck1'),Ccarrying (cr2,ck2') ->

          unify_carrier cr1 cr2;

          unify ck1' ck2'

      | Ccarrying (_,_),_ | _,Ccarrying (_,_) ->

          raise (Unify (ck1,ck2))

      | Carrow (c1,c2), Carrow (c1',c2') ->

          unify c1 c1'; unify c2 c2'

      | Ctuple ckl1, Ctuple ckl2 ->

          if (List.length ckl1) <> (List.length ckl2) then

            raise (Unify (ck1,ck2));

          List.iter2 unify ckl1 ckl2

      | Con (ck',c1,l1), Con (ck'',c2,l2) when l1=l2 ->

          unify_carrier c1 c2;

          unify ck' ck''

      | Pck_const (i,r), Pck_const (i',r') ->

          if i<>i' || r <> r' then

            raise (Unify (ck1,ck2))

      | (_, Pck_up (pck2',k)) when (not right_const) ->

          let ck1' = simplify (new_ck (Pck_down (ck1,k)) true) in

          unify ck1' pck2'

      | (_,Pck_down (pck2',k)) when (not right_const) ->

          subsume ck1 (CSet_pck (k,(0,1)));

          let ck1' = simplify (new_ck (Pck_up (ck1,k)) true) in

          unify ck1' pck2'

      | (_,Pck_phase (pck2',(a,b))) when (not right_const) ->

          subsume ck1 (CSet_pck (b,(a,b)));

          let ck1' = simplify (new_ck (Pck_phase (ck1,(-a,b))) true) in

          unify ck1' pck2'

      | Pck_up (pck1',k),_ ->

          let ck2' = simplify (new_ck (Pck_down (ck2,k)) true) in

          unify pck1' ck2'

      | Pck_down (pck1',k),_ ->

          subsume ck2 (CSet_pck (k,(0,1)));

          let ck2' = simplify (new_ck (Pck_up (ck2,k)) true) in

          unify pck1' ck2'

      | Pck_phase (pck1',(a,b)),_ ->

          subsume ck2 (CSet_pck (b,(a,b)));

          let ck2' = simplify (new_ck (Pck_phase (ck2,(-a,b))) true) in

          unify pck1' ck2'

      | Cunivar _, _ | _, Cunivar _ -> ()

      | _,_ -> raise (Unify (ck1,ck2))

(** [unify ck1 ck2] semi-unifies clocks [ck1] and [ck2]. Raises [Unify

    (ck1,ck2)] if the clocks are not semi-unifiable.*)

let rec semi_unify ck1 ck2 =

  let ck1 = repr ck1 in

  let ck2 = repr ck2 in

  if ck1==ck2 then

    ()

  else

      match ck1.cdesc,ck2.cdesc with

      | Cvar cset1,Cvar cset2->

          if ck1.cid < ck2.cid then

            begin

              ck2.cdesc <- Clink (simplify ck1);

              update_scope ck2.cscoped ck1

            end

          else

            begin

              ck1.cdesc <- Clink (simplify ck2);

              update_scope ck1.cscoped ck2

            end

      | (Cvar cset,_) -> raise (Unify (ck1,ck2))

      | (_, (Cvar cset)) when (not (occurs ck2 ck1)) ->

          update_scope ck2.cscoped ck1;

          ck2.cdesc <- Clink (simplify ck1)

      | Ccarrying (cr1,ck1'),Ccarrying (cr2,ck2') ->

          semi_unify_carrier cr1 cr2;

          semi_unify ck1' ck2'

      | Ccarrying (_,_),_ | _,Ccarrying (_,_) ->

          raise (Unify (ck1,ck2))

      | Carrow (c1,c2), Carrow (c1',c2') ->

	begin

          semi_unify c1 c1';

	  semi_unify c2 c2'

	end

      | Ctuple ckl1, Ctuple ckl2 ->

          if (List.length ckl1) <> (List.length ckl2) then

            raise (Unify (ck1,ck2));

          List.iter2 semi_unify ckl1 ckl2

      | Con (ck',c1,l1), Con (ck'',c2,l2) when l1=l2 ->

          semi_unify_carrier c1 c2;

          semi_unify ck' ck''

      | Cunivar _, _ | _, Cunivar _ -> ()

      | _,_ -> raise (Unify (ck1,ck2))

(* Returns the value corresponding to a pclock (integer) factor

   expression. Expects a constant expression (checked by typing). *)

let int_factor_of_expr e =

  match e.expr_desc with 

  | Expr_const

      (Const_int i) -> i

  | _ -> failwith "Internal error: int_factor_of_expr"

(** [clock_uncarry ck] drops the possible carrier name from clock [ck] *)

let clock_uncarry ck =

  let ck = repr ck in

  match ck.cdesc with

  | Ccarrying (_, ck') -> ck'

  | _                  -> ck

let try_unify ck1 ck2 loc =

  try

    unify ck1 ck2

  with

  | Unify (ck1',ck2') ->

    raise (Error (loc, Clock_clash (ck1',ck2')))

  | Subsume (ck,cset) ->

    raise (Error (loc, Clock_set_mismatch (ck,cset)))

  | Mismatch (cr1,cr2) ->

    raise (Error (loc, Carrier_mismatch (cr1,cr2)))

let try_semi_unify ck1 ck2 loc =

  try

    semi_unify ck1 ck2

  with

  | Unify (ck1',ck2') ->

    raise (Error (loc, Clock_clash (ck1',ck2')))

  | Subsume (ck,cset) ->

    raise (Error (loc, Clock_set_mismatch (ck,cset)))

  | Mismatch (cr1,cr2) ->

    raise (Error (loc, Carrier_mismatch (cr1,cr2)))

(* ck1 is a subtype of ck2 *)

let rec sub_unify sub ck1 ck2 =

  match (repr ck1).cdesc, (repr ck2).cdesc with

  | Ctuple cl1         , Ctuple cl2         ->

    if List.length cl1 <> List.length cl2

    then raise (Unify (ck1, ck2))

    else List.iter2 (sub_unify sub) cl1 cl2

  | Ctuple [c1]        , _                  -> sub_unify sub c1 ck2

  | _                  , Ctuple [c2]        -> sub_unify sub ck1 c2

  | Con (c1, cr1, t1)  , Con (c2, cr2, t2) when t1=t2 ->

    begin

      unify_carrier cr1 cr2;

      sub_unify sub c1 c2

    end

  | Ccarrying (cr1, c1), Ccarrying (cr2, c2)->

    begin

      unify_carrier cr1 cr2;

      sub_unify sub c1 c2

    end

  | Ccarrying (_, c1)  , _         when sub -> sub_unify sub c1 ck2

  | _                                       -> unify ck1 ck2

let try_sub_unify sub ck1 ck2 loc =

  try

    sub_unify sub ck1 ck2

  with

  | Unify (ck1',ck2') ->

    raise (Error (loc, Clock_clash (ck1',ck2')))

  | Subsume (ck,cset) ->

    raise (Error (loc, Clock_set_mismatch (ck,cset)))

  | Mismatch (cr1,cr2) ->

    raise (Error (loc, Carrier_mismatch (cr1,cr2)))

(* Unifies all the clock variables in the clock type of a tuple 

   expression, so that the clock type only uses at most one clock variable *)

let unify_tuple_clock ref_ck_opt ck loc =

  let ck_var = ref ref_ck_opt in

  let rec aux ck =

    match (repr ck).cdesc with

    | Con _

    | Cvar _ ->

        begin

          match !ck_var with

          | None ->

              ck_var:=Some ck

          | Some v ->

              (* may fail *)

              try_unify v ck loc

        end

    | Ctuple cl ->

        List.iter aux cl

    | Carrow _ -> assert false (* should not occur *)

    | Ccarrying (_, ck1) ->

        aux ck1

    | _ -> ()

  in

  aux ck

(* Unifies all the clock variables in the clock type of an imported

   node, so that the clock type only uses at most one base clock variable,

   that is, the activation clock of the node *)

let unify_imported_clock ref_ck_opt ck loc =

  let ck_var = ref ref_ck_opt in

  let rec aux ck =

    match (repr ck).cdesc with

    | Cvar _ ->

        begin

          match !ck_var with

          | None ->

              ck_var:=Some ck

          | Some v ->

              (* cannot fail *)

              try_unify v ck loc

        end

    | Ctuple cl ->

        List.iter aux cl

    | Carrow (ck1,ck2) ->

        aux ck1; aux ck2

    | Ccarrying (_, ck1) ->

        aux ck1

    | Con (ck1, _, _) -> aux ck1

    | _ -> ()

  in

  aux ck

(* Clocks a list of arguments of Lustre builtin operators:

   - type each expression, remove carriers of clocks as

     carriers may only denote variables, not arbitrary expr.

   - try to unify these clocks altogether

*)

let rec clock_standard_args env expr_list =

  let ck_list = List.map (fun e -> clock_uncarry (clock_expr env e)) expr_list in

  let ck_res = new_var true in

  List.iter2 (fun e ck -> try_unify ck ck_res e.expr_loc) expr_list ck_list;

  ck_res

(* emulates a subtyping relation between clocks c and (cr : c),

   used during node application only *)

and clock_subtyping_arg env ?(sub=true) real_arg formal_clock =

  let loc = real_arg.expr_loc in

  let real_clock = clock_expr env real_arg in

  try_sub_unify sub real_clock formal_clock loc

(* computes clocks for node application *)

and clock_appl env f args clock_reset loc =

 let args = expr_list_of_expr args in

  if Basic_library.is_internal_fun f && List.exists is_tuple_expr args

  then

      let args = Utils.transpose_list (List.map expr_list_of_expr args) in

      Clocks.clock_of_clock_list (List.map (fun args -> clock_call env f args clock_reset loc) args)

  else

    clock_call env f args clock_reset loc

and clock_call env f args clock_reset loc =

  let cfun = clock_ident false env f loc in

  let cins, couts = split_arrow cfun in

  let cins = clock_list_of_clock cins in

  List.iter2 (clock_subtyping_arg env) args cins;

  unify_imported_clock (Some clock_reset) cfun loc;

  couts

and clock_ident nocarrier env id loc =

  clock_expr ~nocarrier:nocarrier env (expr_of_ident id loc)

and clock_carrier env c loc ce =

  let expr_c = expr_of_ident c loc in

  let ck = clock_expr ~nocarrier:false env expr_c in

  let cr = new_carrier Carry_name (*Carry_const c*) ck.cscoped in

  let ckcarry = new_ck (Ccarrying (cr,ce)) ck.cscoped in

  try_unify ck ckcarry expr_c.expr_loc;

  ce, cr

(** [clock_expr env expr] performs the clock calculus for expression [expr] in

    environment [env] *)

and clock_expr ?(nocarrier=true) env expr =

  let resulting_ck = 

    match expr.expr_desc with

      | Expr_const cst ->

      let ck = new_var true in

      expr.expr_clock <- ck;

      ck

  | Expr_ident v ->

      let ckv =

        try

          Env.lookup_value env v

        with Not_found -> 

	  failwith ("Internal error, variable \""^v^"\" not found")

      in

      let ck = instantiate (ref []) (ref []) ckv in

      expr.expr_clock <- ck;

      ck

  | Expr_array elist ->

    let ck = clock_standard_args env elist in

    expr.expr_clock <- ck;

    ck

  | Expr_access (e1, d) ->

    (* dimension, being a static value, doesn't need to be clocked *)

    let ck = clock_standard_args env [e1] in

    expr.expr_clock <- ck;

    ck

  | Expr_power (e1, d) ->

    (* dimension, being a static value, doesn't need to be clocked *)

    let ck = clock_standard_args env [e1] in

    expr.expr_clock <- ck;

    ck

  | Expr_tuple elist ->

    let ck = new_ck (Ctuple (List.map (clock_expr env) elist)) true in

    expr.expr_clock <- ck;

    ck

  | Expr_ite (c, t, e) ->

    let ck_c = clock_standard_args env [c] in

    let ck = clock_standard_args env [t; e] in

    (* Here, the branches may exhibit a tuple clock, not the condition *)

    unify_tuple_clock (Some ck_c) ck expr.expr_loc;

    expr.expr_clock <- ck;

    ck

  | Expr_appl (id, args, r) ->

    (try

(* for a modular compilation scheme, all inputs/outputs must share the same clock !

   this is also the reset clock !

*)

    let cr =

      match r with

      | None        -> new_var true

      | Some (x, _) -> let loc_r = loc_of_cond expr.expr_loc x in

		       let expr_r = expr_of_ident x loc_r in

		       clock_expr env expr_r in

    let couts = clock_appl env id args cr expr.expr_loc in

    expr.expr_clock <- couts;

    couts

    with exn -> (

      Format.eprintf "Current expr: %a@." Printers.pp_expr expr; 

      raise exn

    ))

  | Expr_fby (e1,e2)

  | Expr_arrow (e1,e2) ->

    let ck = clock_standard_args env [e1; e2] in

    unify_tuple_clock None ck expr.expr_loc;

    expr.expr_clock <- ck;

    ck

  | Expr_pre e -> (* todo : deal with phases as in tail ? *)

      let ck = clock_standard_args env [e] in

      expr.expr_clock <- ck;

      ck

  | Expr_when (e,c,l) ->

      let ce = clock_standard_args env [e] in

      let c_loc = loc_of_cond expr.expr_loc c in

      let ck_c, cr = clock_carrier env c c_loc ce in

      let ck = new_ck (Con (ce,cr,l)) true in

      let cr' = new_carrier (Carry_const c) ck.cscoped in

      let ck' = new_ck (Con (ce,cr',l)) true in

      unify_tuple_clock (Some ck_c) ce expr.expr_loc;

      expr.expr_clock <- ck';

      ck

  | Expr_merge (c,hl) ->

      let cvar = new_var true in

      let ck_c, cr = clock_carrier env c expr.expr_loc cvar in

      List.iter (fun (t, h) -> clock_subtyping_arg env h (new_ck (Con (cvar,cr,t)) true)) hl;

      unify_tuple_clock (Some ck_c) cvar expr.expr_loc;

      expr.expr_clock <- cvar;

      cvar

  in

  Log.report ~level:4 (fun fmt -> Format.fprintf fmt "Clock of expr %a: %a@." Printers.pp_expr expr Clocks.print_ck resulting_ck);

  resulting_ck

let clock_of_vlist vars =

  let ckl = List.map (fun v -> v.var_clock) vars in

  clock_of_clock_list ckl

(** [clock_eq env eq] performs the clock-calculus for equation [eq] in

    environment [env] *)

let clock_eq env eq =

  let expr_lhs = expr_of_expr_list eq.eq_loc (List.map (fun v -> expr_of_ident v eq.eq_loc) eq.eq_lhs) in

  let ck_rhs = clock_expr env eq.eq_rhs in

  clock_subtyping_arg env expr_lhs ck_rhs

(* [clock_coreclock cck] returns the clock_expr corresponding to clock

    declaration [cck] *)

let clock_coreclock env cck id loc scoped =

  match cck.ck_dec_desc with

  | Ckdec_any -> new_var scoped

  | Ckdec_pclock (n,(a,b)) ->

      let ck = new_ck (Pck_const (n,(a,b))) scoped in

      if n mod b <> 0 then raise (Error (loc,Invalid_const ck));

      ck

  | Ckdec_bool cl ->

      let temp_env = Env.add_value env id (new_var true) in

      (* We just want the id to be present in the environment *)

      let dummy_id_expr = expr_of_ident id loc in

      let when_expr =

        List.fold_left

          (fun expr (x,l) ->

                {expr_tag = new_tag ();

                 expr_desc = Expr_when (expr,x,l);

                 expr_type = Types.new_var ();

                 expr_clock = new_var scoped;

                 expr_delay = Delay.new_var ();

                 expr_loc = loc;

		 expr_annot = None})

          dummy_id_expr cl

      in

      clock_expr temp_env when_expr

(* Clocks a variable declaration *)

let clock_var_decl scoped env vdecl =

  let ck = clock_coreclock env vdecl.var_dec_clock vdecl.var_id vdecl.var_loc scoped in

  let ck =

(* WTF ????

    if vdecl.var_dec_const

    then

      (try_generalize ck vdecl.var_loc; ck)

    else

 *)

      if Types.get_clock_base_type vdecl.var_type <> None

      then new_ck (Ccarrying ((new_carrier Carry_name scoped),ck)) scoped

      else ck in

  vdecl.var_clock <- ck;

  Env.add_value env vdecl.var_id ck

(* Clocks a variable declaration list *)

let clock_var_decl_list env scoped l =

  List.fold_left (clock_var_decl scoped) env l

(** [clock_node env nd] performs the clock-calculus for node [nd] in

    environment [env].

    Generalization of clocks wrt scopes follows this rule:

    - generalize inputs (unscoped).

    - generalize outputs. As they are scoped, only clocks coming from inputs

      are allowed to be generalized.

    - generalize locals. As outputs don't depend on them (checked the step before),

      they can be generalized. 

 *)

let clock_node env loc nd =

  (* let is_main = nd.node_id = !Options.main_node in *)

  let new_env = clock_var_decl_list env false nd.node_inputs in

  let new_env = clock_var_decl_list new_env true nd.node_outputs in

  let new_env = clock_var_decl_list new_env true nd.node_locals in

  List.iter (clock_eq new_env) nd.node_eqs;

  let ck_ins = clock_of_vlist nd.node_inputs in

  let ck_outs = clock_of_vlist nd.node_outputs in

  let ck_node = new_ck (Carrow (ck_ins,ck_outs)) false in

  unify_imported_clock None ck_node loc;

  Log.report ~level:3 (fun fmt -> print_ck fmt ck_node);

  (* Local variables may contain first-order carrier variables that should be generalized.

     That's not the case for types. *)

  try_generalize ck_node loc;

(*

  List.iter (fun vdecl -> try_generalize vdecl.var_clock vdecl.var_loc) nd.node_inputs;

  List.iter (fun vdecl -> try_generalize vdecl.var_clock vdecl.var_loc) nd.node_outputs;*)

  (*List.iter (fun vdecl -> try_generalize vdecl.var_clock vdecl.var_loc) nd.node_locals;*)

  (* TODO : Xavier pourquoi ai je cette erreur ? *)

(*  if (is_main && is_polymorphic ck_node) then

    raise (Error (loc,(Cannot_be_polymorphic ck_node)));

*)

  Log.report ~level:3 (fun fmt -> print_ck fmt ck_node);

  nd.node_clock <- ck_node;

  Env.add_value env nd.node_id ck_node

let check_imported_pclocks loc ck_node =

  let pck = ref None in

  let rec aux ck =

    match ck.cdesc with

    | Carrow (ck1,ck2) -> aux ck1; aux ck2

    | Ctuple cl -> List.iter aux cl

    | Con (ck',_,_) -> aux ck'

    | Pck_up (_,_) | Pck_down (_,_) | Pck_phase (_,_) -> 

        raise (Error (loc, (Invalid_imported_clock ck_node)))

    | Pck_const (n,p) ->

        begin

          match !pck with

          | None -> pck := Some (n,p)

          | Some (n',p') ->

              if (n,p) <> (n',p') then

                raise (Error (loc, (Invalid_imported_clock ck_node)))

        end

    | Clink ck' -> aux ck'

    | Ccarrying (_,ck') -> aux ck'

    | Cvar _ | Cunivar _ ->

        match !pck with

        | None -> ()

        | Some (_,_) ->

            raise (Error (loc, (Invalid_imported_clock ck_node)))

  in

  aux ck_node

let clock_imported_node env loc nd =

  let new_env = clock_var_decl_list env false nd.nodei_inputs in

  ignore(clock_var_decl_list new_env false nd.nodei_outputs);

  let ck_ins = clock_of_vlist nd.nodei_inputs in

  let ck_outs = clock_of_vlist nd.nodei_outputs in

  let ck_node = new_ck (Carrow (ck_ins,ck_outs)) false in

  unify_imported_clock None ck_node loc;

  check_imported_pclocks loc ck_node;

  try_generalize ck_node loc;

  nd.nodei_clock <- ck_node;

  Env.add_value env nd.nodei_id ck_node

let clock_top_consts env clist =

  List.fold_left (fun env cdecl ->

    let ck = new_var false in

    try_generalize ck cdecl.const_loc;

    Env.add_value env cdecl.const_id ck) env clist

let clock_top_decl env decl =

  match decl.top_decl_desc with

  | Node nd ->

    clock_node env decl.top_decl_loc nd

  | ImportedNode nd ->

    clock_imported_node env decl.top_decl_loc nd

  | Consts clist ->

    clock_top_consts env clist

  | Open _ ->

    env

let clock_prog env decls =

  List.fold_left (fun e decl -> clock_top_decl e decl) env decls

(* Once the Lustre program is fully clocked,

   we must get back to the original description of clocks,

   with constant parameters, instead of unifiable internal variables. *)

(* The following functions aims at 'unevaluating' carriers occuring in clock expressions,

   i.e. replacing unifiable second_order variables with the original carrier names.

   Once restored in this formulation, clocks may be meaningfully printed.

*)

let uneval_vdecl_generics vdecl =

 (*Format.eprintf "Clock_calculus.uneval_vdecl_generics %a@." Printers.pp_node_var vdecl;*)

 if Types.get_clock_base_type vdecl.var_type <> None

 then

   match get_carrier_name vdecl.var_clock with

   | None    -> (Format.eprintf "internal error: %a@." print_ck vdecl.var_clock; assert false)

   | Some cr -> Clocks.uneval vdecl.var_id cr

let uneval_node_generics vdecls =

  List.iter uneval_vdecl_generics vdecls

let uneval_top_generics decl =

  match decl.top_decl_desc with

  | Node nd ->

      (* A node could contain first-order carrier variable in local vars. This is not the case for types. *)

      uneval_node_generics (nd.node_inputs @ nd.node_locals @ nd.node_outputs)

  | ImportedNode nd ->

      uneval_node_generics (nd.nodei_inputs @ nd.nodei_outputs)

  | Consts clist -> ()

  | Open _  -> ()

let uneval_prog_generics prog =

 List.iter uneval_top_generics prog

let check_env_compat header declared computed =

  uneval_prog_generics header;

  Env.iter declared (fun k decl_clock_k -> 

    let computed_c = instantiate (ref []) (ref []) (Env.lookup_value computed k) in

    try_semi_unify decl_clock_k computed_c Location.dummy_loc

  ) 

(* Local Variables: *)

(* compile-command:"make -C .." *)

(* End: *)