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(********************************************************************)
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(*                                                                  *)
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(*  The LustreC compiler toolset   /  The LustreC Development Team  *)
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(*  Copyright 2012 -    --   ONERA - CNRS - INPT - LIFL             *)
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(*                                                                  *)
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(*  LustreC is free software, distributed WITHOUT ANY WARRANTY      *)
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(*  under the terms of the GNU Lesser General Public License        *)
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(*  version 2.1.                                                    *)
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(*                                                                  *) 
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(*  This file was originally from the Prelude compiler              *)
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(*                                                                  *) 
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(********************************************************************)
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(** Simple modular syntactic causality analysis. Can reject correct
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    programs, especially if the program is not flattened first. *)
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open Utils
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open Lustre_types
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open Corelang
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open Graph
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type identified_call = eq * tag
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type error =
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  | DataCycle of ident list list (* multiple failed partitions at once *) 
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  | NodeCycle of ident list
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exception Error of error
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(* Dependency of mem variables on mem variables is cut off 
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   by duplication of some mem vars into local node vars.
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   Thus, cylic dependency errors may only arise between no-mem vars.
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   non-mem variables are:
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   - constants/inputs: not needed for causality/scheduling, needed only for detecting useless vars
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   - read mems (fake vars): same remark as above.
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   - outputs: decoupled from mems, if necessary
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   - locals
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   - instance vars (fake vars): simplify causality analysis
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   global constants are not part of the dependency graph.
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   no_mem' = combinational(no_mem, mem);
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   => (mem -> no_mem' -> no_mem)
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   mem' = pre(no_mem, mem);
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   => (mem' -> no_mem), (mem -> mem')
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   Global roadmap:
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   - compute two dep graphs g (non-mem/non-mem&mem) and g' (mem/mem)
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   - check cycles in g (a cycle means a dependency error)
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   - break cycles in g' (it's legal !):
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     - check cycles in g'
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     - if any, introduce aux var to break cycle, then start afresh
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   - insert g' into g
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   - return g
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*)
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(* Tests whether [v] is a root of graph [g], i.e. a source *)
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let is_graph_root v g =
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  IdentDepGraph.in_degree g v = 0
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(* Computes the set of graph roots, i.e. the sources of acyclic graph [g] *)
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let graph_roots g =
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  IdentDepGraph.fold_vertex
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    (fun v roots -> if is_graph_root v g then v::roots else roots)
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    g []
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let add_edges src tgt g =
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 (*List.iter (fun s -> List.iter (fun t -> Format.eprintf "add %s -> %s@." s t) tgt) src;*)
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  List.iter
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    (fun s ->
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      List.iter
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	(fun t -> IdentDepGraph.add_edge g s t)
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	tgt)
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    src;
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  g
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let add_vertices vtc g =
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 (*List.iter (fun t -> Format.eprintf "add %s@." t) vtc;*)
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  List.iter (fun v -> IdentDepGraph.add_vertex g v) vtc;
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  g
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let new_graph () =
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  IdentDepGraph.create ()
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(* keep subgraph of [gr] consisting of nodes accessible from node [v] *)
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let slice_graph gr v =
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  begin
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    let gr' = new_graph () in
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    IdentDepGraph.add_vertex gr' v;
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    Bfs.iter_component (fun v -> IdentDepGraph.iter_succ (fun s -> IdentDepGraph.add_vertex gr' s; IdentDepGraph.add_edge gr' v s) gr v) gr v;
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    gr'
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  end
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module ExprDep = struct
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  let get_node_eqs nd =
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    let eqs, auts = get_node_eqs nd in
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    if auts != [] then assert false (* No call on causality on a Lustre model
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				       with automaton. They should be expanded by now. *);
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    eqs
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  let instance_var_cpt = ref 0
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(* read vars represent input/mem read-only vars,
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   they are not part of the program/schedule,
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   as they are not assigned,
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   but used to compute useless inputs/mems.
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   a mem read var represents a mem at the beginning of a cycle  *)
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  let mk_read_var id =
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    Format.sprintf "#%s" id
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(* instance vars represent node instance calls,
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   they are not part of the program/schedule,
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   but used to simplify causality analysis
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*)
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  let mk_instance_var id =
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    incr instance_var_cpt; Format.sprintf "!%s_%d" id !instance_var_cpt
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  let is_read_var v = v.[0] = '#'
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  let is_instance_var v = v.[0] = '!'
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  let is_ghost_var v = is_instance_var v || is_read_var v
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  let undo_read_var id =
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    assert (is_read_var id);
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    String.sub id 1 (String.length id - 1)
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  let undo_instance_var id =
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    assert (is_instance_var id);
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    String.sub id 1 (String.length id - 1)
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  let eq_memory_variables mems eq =
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    let rec match_mem lhs rhs mems =
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      match rhs.expr_desc with
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      | Expr_fby _
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      | Expr_pre _    -> List.fold_right ISet.add lhs mems
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      | Expr_tuple tl -> 
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	 let lhs' = (transpose_list [lhs]) in
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	 List.fold_right2 match_mem lhs' tl mems
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      | _             -> mems in
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    match_mem eq.eq_lhs eq.eq_rhs mems
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  let node_memory_variables nd =
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    List.fold_left eq_memory_variables ISet.empty (get_node_eqs nd)
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  let node_input_variables nd =
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    List.fold_left (fun inputs v -> ISet.add v.var_id inputs) ISet.empty 
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      (if nd.node_iscontract then
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         nd.node_inputs@nd.node_outputs
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       else
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         nd.node_inputs)
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  let node_output_variables nd =
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    List.fold_left (fun outputs v -> ISet.add v.var_id outputs) ISet.empty
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      (if nd.node_iscontract then [] else nd.node_outputs)
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  let node_local_variables nd =
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    List.fold_left (fun locals v -> ISet.add v.var_id locals) ISet.empty nd.node_locals
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  let node_constant_variables nd =
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    List.fold_left (fun locals v -> if v.var_dec_const then ISet.add v.var_id locals else locals) ISet.empty nd.node_locals
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  let node_auxiliary_variables nd =
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    ISet.diff (node_local_variables nd) (node_memory_variables nd)
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  let node_variables nd =
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    let inputs = node_input_variables nd in
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    let inoutputs = List.fold_left (fun inoutputs v -> ISet.add v.var_id inoutputs) inputs nd.node_outputs in
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    List.fold_left (fun vars v -> ISet.add v.var_id vars) inoutputs nd.node_locals
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(* computes the equivalence relation relating variables 
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   in the same equation lhs, under the form of a table 
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   of class representatives *)
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  let eqs_eq_equiv eqs =
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    let eq_equiv = Hashtbl.create 23 in
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    List.iter (fun eq ->
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      let first = List.hd eq.eq_lhs in
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      List.iter (fun v -> Hashtbl.add eq_equiv v first) eq.eq_lhs
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    )
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      eqs;
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    eq_equiv
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187
  let node_eq_equiv nd = eqs_eq_equiv  (get_node_eqs nd)
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(* Create a tuple of right dimension, according to [expr] type, *)
190
(* filled with variable [v] *)
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  let adjust_tuple v expr =
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    match expr.expr_type.Types.tdesc with
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    | Types.Ttuple tl -> duplicate v (List.length tl)
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    | _         -> [v]
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  (* Add dependencies from lhs to rhs in [g, g'], *)
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  (* no-mem/no-mem and mem/no-mem in g            *)
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  (* mem/mem in g'                                *)
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  (*     match (lhs_is_mem, ISet.mem x mems) with
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	 | (false, true ) -> (add_edges [x] lhs g,
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	 g')
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	 | (false, false) -> (add_edges lhs [x] g,
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	 g')
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	 | (true , false) -> (add_edges lhs [x] g,
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	 g')
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	 | (true , true ) -> (g,
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	 add_edges [x] lhs g')
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  *)
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  let add_eq_dependencies mems inputs node_vars eq (g, g') =
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    let add_var lhs_is_mem lhs x (g, g') =
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      if is_instance_var x || ISet.mem x node_vars then
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	if ISet.mem x mems
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	then
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	  let g = add_edges lhs [mk_read_var x] g in
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	  if lhs_is_mem
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	  then
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	    (g, add_edges [x] lhs g')
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	  else
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	    (add_edges [x] lhs g, g')
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	else
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	  let x = if ISet.mem x inputs then mk_read_var x else x in
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	  (add_edges lhs [x] g, g')
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      else (add_edges lhs [mk_read_var x] g, g') (* x is a global constant, treated as a read var *)
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    in
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  (* Add dependencies from [lhs] to rhs clock [ck]. *)
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    let rec add_clock lhs_is_mem lhs ck g =
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    (*Format.eprintf "add_clock %a@." Clocks.print_ck ck;*)
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      match (Clocks.repr ck).Clocks.cdesc with
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      | Clocks.Con (ck', cr, _)   -> add_var lhs_is_mem lhs (Clocks.const_of_carrier cr) (add_clock lhs_is_mem lhs ck' g)
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      | Clocks.Ccarrying (_, ck') -> add_clock lhs_is_mem lhs ck' g
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      | _                         -> g 
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    in
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    let rec add_dep lhs_is_mem lhs rhs g =
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    (* Add mashup dependencies for a user-defined node instance [lhs] = [f]([e]) *)
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    (* i.e every input is connected to every output, through a ghost var *)
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      let mashup_appl_dependencies f e g =
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	let f_var = mk_instance_var (Format.sprintf "%s_%d" f eq.eq_loc.Location.loc_start.Lexing.pos_lnum) in
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	List.fold_right (fun rhs -> add_dep lhs_is_mem (adjust_tuple f_var rhs) rhs)
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	  (expr_list_of_expr e) (add_var lhs_is_mem lhs f_var g) 
241
      in
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      match rhs.expr_desc with
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      | Expr_const _    -> g
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      | Expr_fby (e1, e2)  -> add_dep true lhs e2 (add_dep false lhs e1 g)
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      | Expr_pre e      -> add_dep true lhs e g
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      | Expr_ident x -> add_var lhs_is_mem lhs x (add_clock lhs_is_mem lhs rhs.expr_clock g)
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      | Expr_access (e1, d)
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      | Expr_power (e1, d) -> add_dep lhs_is_mem lhs e1 (add_dep lhs_is_mem lhs (expr_of_dimension d) g)
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      | Expr_array a -> List.fold_right (add_dep lhs_is_mem lhs) a g
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      | Expr_tuple t -> List.fold_right2 (fun l r -> add_dep lhs_is_mem [l] r) lhs t g
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      | Expr_merge (c, hl) -> add_var lhs_is_mem lhs c (List.fold_right (fun (_, h) -> add_dep lhs_is_mem lhs h) hl g)
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      | Expr_ite   (c, t, e) -> add_dep lhs_is_mem lhs c (add_dep lhs_is_mem lhs t (add_dep lhs_is_mem lhs e g))
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      | Expr_arrow (e1, e2)  -> add_dep lhs_is_mem lhs e2 (add_dep lhs_is_mem lhs e1 g)
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      | Expr_when  (e, c, _)  -> add_dep lhs_is_mem lhs e (add_var lhs_is_mem lhs c g)
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      | Expr_appl (f, e, None) ->
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	 if Basic_library.is_expr_internal_fun rhs
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      (* tuple component-wise dependency for internal operators *)
258
	 then
259
	   List.fold_right (add_dep lhs_is_mem lhs) (expr_list_of_expr e) g
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      (* mashed up dependency for user-defined operators *)
261
	 else
262
	   mashup_appl_dependencies f e g
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      | Expr_appl (f, e, Some c) ->
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	 mashup_appl_dependencies f e (add_dep lhs_is_mem lhs c g)
265
    in
266
    let g =
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      List.fold_left
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	(fun g lhs ->
269
	  if ISet.mem lhs mems then
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	    add_vertices [lhs; mk_read_var lhs] g
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	  else
272
	    add_vertices [lhs] g
273
	)
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	g eq.eq_lhs
275
    in
276
    add_dep false eq.eq_lhs eq.eq_rhs (g, g')
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  (* Returns the dependence graph for node [n] *)
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  let dependence_graph mems inputs node_vars n =
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    instance_var_cpt := 0;
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    let g = new_graph (), new_graph () in
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    (* Basic dependencies *)
284
    let g = List.fold_right (add_eq_dependencies mems inputs node_vars) (get_node_eqs n) g in
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    (* TODO Xavier: un essai ci dessous. Ca n'a pas l'air de résoudre le pb. Il
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       faut imposer que les outputs dépendent des asserts pour identifier que les
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       fcn calls des asserts sont évalués avant le noeuds *)
288
    
289
    (* (\* In order to introduce dependencies between assert expressions and the node, *)
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    (*    we build an artificial dependency between node output and each assert *)
291
    (*    expr. While these are not valid equations, they should properly propage in *)
292
    (*    function add_eq_dependencies *\) *)
293
    (* let g = *)
294
    (*   let output_vars_as_lhs = ISet.elements (node_output_variables n) in *)
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    (*   List.fold_left (fun g ae -> *)
296
    (*     let fake_eq = mkeq Location.dummy_loc (output_vars_as_lhs, ae.assert_expr) in *)
297
    (*   add_eq_dependencies mems inputs node_vars fake_eq g *)
298
    (* ) g n.node_asserts in  *)
299
    g
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301
end
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303
module NodeDep = struct
304

    
305
  module ExprModule =
306
  struct
307
    type t = expr
308
    let compare = compare
309
    let hash n = Hashtbl.hash n
310
    let equal n1 n2 = n1 = n2
311
  end
312

    
313
  module ESet = Set.Make(ExprModule)
314

    
315
  let rec get_expr_calls prednode expr = 
316
    match expr.expr_desc with
317
    | Expr_const _ 
318
    | Expr_ident _ -> ESet.empty
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    | Expr_access (e, _)
320
    | Expr_power (e, _) -> get_expr_calls prednode e
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    | Expr_array t
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    | Expr_tuple t -> List.fold_right (fun x set -> ESet.union (get_expr_calls prednode x) set) t ESet.empty
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    | Expr_merge (_,hl) -> List.fold_right (fun (_,h) set -> ESet.union (get_expr_calls prednode h) set) hl ESet.empty
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    | Expr_fby (e1,e2)
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    | Expr_arrow (e1,e2) -> ESet.union (get_expr_calls prednode e1) (get_expr_calls prednode e2)
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    | Expr_ite   (c, t, e) -> ESet.union (get_expr_calls prednode c) (ESet.union (get_expr_calls prednode t) (get_expr_calls prednode e))
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    | Expr_pre e 
328
    | Expr_when (e,_,_) -> get_expr_calls prednode e
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    | Expr_appl (id,e, _) ->
330
       if not (Basic_library.is_expr_internal_fun expr) && prednode id
331
       then ESet.add expr (get_expr_calls prednode e)
332
       else (get_expr_calls prednode e)
333

    
334
  let get_eexpr_calls prednode ee =
335
    get_expr_calls prednode ee.eexpr_qfexpr
336
    
337
  let get_callee expr =
338
    match expr.expr_desc with
339
    | Expr_appl (id, args, _) -> Some (id, expr_list_of_expr args)
340
    | _ -> None
341

    
342
  let accu f init objl = List.fold_left (fun accu o -> ESet.union accu (f o)) init objl 
343

    
344
  let get_eq_calls prednode eq = get_expr_calls prednode eq.eq_rhs
345
                      
346
  let rec get_stmt_calls prednode s =
347
    match s with Eq eq -> get_eq_calls prednode eq | Aut aut -> get_aut_calls prednode aut 
348
  and get_aut_calls prednode aut =
349
    let get_handler_calls prednode h =
350
      let get_cond_calls c = accu (fun (_,e,_,_) -> get_expr_calls prednode e) ESet.empty c in
351
      let until = get_cond_calls h.hand_until in
352
      let unless = get_cond_calls h.hand_unless in
353
      let calls = ESet.union until unless in 
354
      let calls = accu (get_stmt_calls prednode) calls h.hand_stmts in
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      let calls = accu (fun a -> get_expr_calls prednode a.assert_expr) calls h.hand_asserts in
356
      (* let calls = accu xx calls h.hand_annots in *) (* TODO: search for calls in eexpr *)
357
      calls
358
    in
359
    accu (get_handler_calls prednode) ESet.empty aut.aut_handlers
360
    
361
  let get_calls prednode nd =
362
    let eqs, auts = get_node_eqs nd in
363
    let deps = accu (get_eq_calls prednode) ESet.empty eqs in
364
    let deps = accu (get_aut_calls prednode) deps auts in
365
    ESet.elements deps
366

    
367
  let get_contract_calls prednode c =
368
    let deps = accu (get_stmt_calls prednode) ESet.empty c.stmts in
369
    let deps = accu (get_eexpr_calls prednode) deps ( c.assume @ c.guarantees @ (List.fold_left (fun accu m -> accu @ m.require @ m.ensure ) [] c.modes)) in
370
    let id_deps = List.map (fun e -> fst (desome (get_callee e))) (ESet.elements deps) in  
371
    let id_deps = (List.fold_left (fun accu imp -> imp.import_nodeid::accu) [] c.imports) @ id_deps in  
372
    id_deps
373
    
374
  let dependence_graph prog =
375
    let g = new_graph () in
376
    let g = List.fold_right 
377
      (fun td accu -> (* for each node we add its dependencies *)
378
	match td.top_decl_desc with 
379
	| Node nd ->
380
	  (*Format.eprintf "Computing deps of node %s@.@?" nd.node_id; *)
381
	   let accu = add_vertices [nd.node_id] accu in
382
	   let deps = List.map
383
	     (fun e -> fst (desome (get_callee e)))
384
	     (get_calls (fun _ -> true) nd) 
385
	   in
386
	     (* Adding assert expressions deps *)
387
	   let deps_asserts =
388
	     let prednode = (fun _ -> true) in (* what is this about? *)
389
	     List.map
390
	       (fun e -> fst (desome (get_callee e)))
391
 	       (ESet.elements
392
		  (List.fold_left
393
		     (fun accu assert_expr -> ESet.union accu (get_expr_calls prednode assert_expr))
394
		     ESet.empty
395
		     (List.map (fun _assert -> _assert.assert_expr) nd.node_asserts)
396
		  )
397
	       )
398
      	   in
399
           let deps_spec = match nd.node_spec with
400
             | None -> []
401
             | Some (NodeSpec id) -> [id]
402
             | Some (Contract c) -> get_contract_calls (fun _ -> true) c
403
                                  
404
           in
405
	   (*Format.eprintf "%a@.@?" (Utils.fprintf_list ~sep:"@." Format.pp_print_string) deps; *)
406
	   add_edges [nd.node_id] (deps@deps_asserts@deps_spec) accu
407
	| _ -> assert false (* should not happen *)
408
	   
409
      ) prog g in
410
    g   
411
      
412
  let rec filter_static_inputs inputs args =
413
    match inputs, args with
414
    | []   , [] -> []
415
    | v::vq, a::aq -> if v.var_dec_const && Types.is_dimension_type v.var_type then (dimension_of_expr a) :: filter_static_inputs vq aq else filter_static_inputs vq aq
416
    | _ -> assert false
417

    
418
  let compute_generic_calls prog =
419
    List.iter
420
      (fun td ->
421
	match td.top_decl_desc with 
422
	| Node nd ->
423
	   let prednode n = is_generic_node (node_from_name n) in
424
	   nd.node_gencalls <- get_calls prednode nd
425
	| _ -> ()
426
	   
427
      ) prog
428

    
429
end
430

    
431

    
432
module CycleDetection = struct
433

    
434
  (* ---- Look for cycles in a dependency graph *)
435
  module Cycles = Graph.Components.Make (IdentDepGraph)
436

    
437
  let mk_copy_var n id =
438
    let used name =
439
      (List.exists (fun v -> v.var_id = name) n.node_locals)
440
      || (List.exists (fun v -> v.var_id = name) n.node_inputs)
441
      || (List.exists (fun v -> v.var_id = name) n.node_outputs)
442
    in mk_new_name used id
443

    
444
  let mk_copy_eq n var =
445
    let var_decl = get_node_var var n in
446
    let cp_var = mk_copy_var n var in
447
    let expr =
448
      { expr_tag = Utils.new_tag ();
449
	expr_desc = Expr_ident var;
450
	expr_type = var_decl.var_type;
451
	expr_clock = var_decl.var_clock;
452
	expr_delay = Delay.new_var ();
453
	expr_annot = None;
454
	expr_loc = var_decl.var_loc } in
455
    { var_decl with var_id = cp_var; var_orig = false },
456
    mkeq var_decl.var_loc ([cp_var], expr)
457

    
458
  let wrong_partition g partition =
459
    match partition with
460
    | [id]    -> IdentDepGraph.mem_edge g id id
461
    | _::_::_ -> true
462
    | []      -> assert false
463

    
464
  (* Checks that the dependency graph [g] does not contain a cycle. Raises
465
     [Cycle partition] if the succession of dependencies [partition] forms a cycle *)
466
  let check_cycles g =
467
    let scc_l = Cycles.scc_list g in
468
    let algebraic_loops = List.filter (wrong_partition g) scc_l in
469
    if List.length algebraic_loops > 0 then
470
      raise (Error (DataCycle algebraic_loops))
471
	(* We extract a hint to resolve the cycle: for each variable in the cycle
472
	   which is defined by a call, we return the name of the node call and
473
	   its specific id *)
474

    
475
  (* Creates the sub-graph of [g] restricted to vertices and edges in partition *)
476
  let copy_partition g partition =
477
    let copy_g = IdentDepGraph.create () in
478
    IdentDepGraph.iter_edges
479
      (fun src tgt ->
480
	if List.mem src partition && List.mem tgt partition
481
	then IdentDepGraph.add_edge copy_g src tgt)
482
      g
483

    
484
      
485
  (* Breaks dependency cycles in a graph [g] by inserting aux variables.
486
     [head] is a head of a non-trivial scc of [g]. 
487
     In Lustre, this is legal only for mem/mem cycles *)
488
  let break_cycle head cp_head g =
489
    let succs = IdentDepGraph.succ g head in
490
    IdentDepGraph.add_edge g head cp_head;
491
    IdentDepGraph.add_edge g cp_head (ExprDep.mk_read_var head);
492
    List.iter
493
      (fun s ->
494
	IdentDepGraph.remove_edge g head s;
495
	IdentDepGraph.add_edge    g s cp_head)
496
      succs
497

    
498
  (* Breaks cycles of the dependency graph [g] of memory variables [mems]
499
     belonging in node [node]. Returns:
500
     - a list of new auxiliary variable declarations
501
     - a list of new equations
502
     - a modified acyclic version of [g]
503
  *)
504
  let break_cycles node mems g =
505
    let eqs , auts = get_node_eqs node in
506
    assert (auts = []); (* TODO: check: For the moment we assume that auts are expanded by now *)
507
    let (mem_eqs, non_mem_eqs) = List.partition (fun eq -> List.exists (fun v -> ISet.mem v mems) eq.eq_lhs) eqs in
508
    let rec break vdecls mem_eqs g =
509
      let scc_l = Cycles.scc_list g in
510
      let wrong = List.filter (wrong_partition g) scc_l in
511
      match wrong with
512
      | []              -> (vdecls, non_mem_eqs@mem_eqs, g)
513
      | [head]::_       ->
514
	 begin
515
	   IdentDepGraph.remove_edge g head head;
516
	   break vdecls mem_eqs g
517
	 end
518
      | (head::part)::_ -> 
519
	 begin
520
	   let vdecl_cp_head, cp_eq = mk_copy_eq node head in
521
	   let pvar v = List.mem v part in
522
	   let fvar v = if v = head then vdecl_cp_head.var_id else v in
523
	   let mem_eqs' = List.map (eq_replace_rhs_var pvar fvar) mem_eqs in
524
	   break_cycle head vdecl_cp_head.var_id g;
525
	   break (vdecl_cp_head::vdecls) (cp_eq::mem_eqs') g
526
	 end
527
      | _               -> assert false
528
    in break [] mem_eqs g
529

    
530
end
531

    
532
(* Module used to compute static disjunction of variables based upon their clocks. *)
533
module Disjunction =
534
struct
535
  module ClockedIdentModule =
536
  struct
537
    type t = var_decl
538
    let root_branch vdecl = Clocks.root vdecl.var_clock, Clocks.branch vdecl.var_clock
539
    let compare v1 v2 = compare (root_branch v2, v2.var_id) (root_branch v1, v1.var_id)
540
  end
541

    
542
  module CISet = Set.Make(ClockedIdentModule)
543

    
544
  (* map: var |-> list of disjoint vars, sorted in increasing branch length order,
545
     maybe removing shorter branches *)
546
  type disjoint_map = (ident, CISet.t) Hashtbl.t
547

    
548
  let pp_ciset fmt t =
549
    begin
550
      Format.fprintf fmt "{@ ";
551
      CISet.iter (fun s -> Format.fprintf fmt "%a@ " Printers.pp_var_name s) t;
552
      Format.fprintf fmt "}@."
553
    end
554

    
555
  let clock_disjoint_map vdecls =
556
    let map = Hashtbl.create 23 in
557
    begin
558
      List.iter
559
	(fun v1 -> let disj_v1 =
560
		     List.fold_left
561
		       (fun res v2 -> if Clocks.disjoint v1.var_clock v2.var_clock then CISet.add v2 res else res)
562
		       CISet.empty
563
		       vdecls in
564
		   (* disjoint vdecls are stored in increasing branch length order *)
565
		   Hashtbl.add map v1.var_id disj_v1)
566
	vdecls;
567
      (map : disjoint_map)
568
    end
569

    
570
  (* merge variables [v] and [v'] in disjunction [map]. Then:
571
     - the mapping v' becomes v' |-> (map v) inter (map v')
572
     - the mapping v |-> ... then disappears
573
     - other mappings become x |-> (map x) \ (if v in x then v else v')
574
  *)
575
  let merge_in_disjoint_map map v v' =
576
    begin
577
      Hashtbl.replace map v'.var_id (CISet.inter (Hashtbl.find map v.var_id) (Hashtbl.find map v'.var_id));
578
      Hashtbl.remove map v.var_id;
579
      Hashtbl.iter (fun x map_x -> Hashtbl.replace map x (CISet.remove (if CISet.mem v map_x then v else v') map_x)) map;
580
    end
581

    
582
  (* replace variable [v] by [v'] in disjunction [map].
583
     [v'] is a dead variable. Then:
584
     - the mapping v' becomes v' |-> (map v)
585
     - the mapping v |-> ... then disappears
586
     - all mappings become x |-> ((map x) \ { v}) union ({v'} if v in map x)
587
  *)
588
  let replace_in_disjoint_map map v v' =
589
    begin
590
      Hashtbl.replace map v'.var_id (Hashtbl.find map v.var_id);
591
      Hashtbl.remove  map v.var_id;
592
      Hashtbl.iter (fun x mapx -> Hashtbl.replace map x (if CISet.mem v mapx then CISet.add v' (CISet.remove v mapx) else CISet.remove v' mapx)) map;
593
    end
594

    
595
  (* remove variable [v] in disjunction [map]. Then:
596
     - the mapping v |-> ... then disappears
597
     - all mappings become x |-> (map x) \ { v}
598
  *)
599
  let remove_in_disjoint_map map v =
600
    begin
601
      Hashtbl.remove map v.var_id;
602
      Hashtbl.iter (fun x mapx -> Hashtbl.replace map x (CISet.remove v mapx)) map;
603
    end
604

    
605
  let pp_disjoint_map fmt map =
606
    begin
607
      Format.fprintf fmt "{ /* disjoint map */@.";
608
      Hashtbl.iter (fun k v -> Format.fprintf fmt "%s # { %a }@." k (Utils.fprintf_list ~sep:", " Printers.pp_var_name) (CISet.elements v)) map;
609
      Format.fprintf fmt "}@."
610
    end
611
end
612

    
613
  
614
let pp_dep_graph fmt g =
615
  begin
616
    Format.fprintf fmt "{ /* graph */@.";
617
    IdentDepGraph.iter_edges (fun s t -> Format.fprintf fmt "%s -> %s@." s t) g;
618
    Format.fprintf fmt "}@."
619
  end
620

    
621
let pp_error fmt err =
622
  match err with
623
  | NodeCycle trace ->
624
     Format.fprintf fmt "Causality error, cyclic node calls:@   @[<v 0>%a@]@ "
625
       (fprintf_list ~sep:",@ " Format.pp_print_string) trace
626
  | DataCycle traces -> (
627
     Format.fprintf fmt "Causality error, cyclic data dependencies:@   @[<v 0>%a@]@ "
628
       (fprintf_list ~sep:";@ "
629
       (fun fmt trace ->
630
	 Format.fprintf fmt "@[<v 0>{%a}@]"
631
	   (fprintf_list ~sep:",@ " Format.pp_print_string)
632
	   trace
633
       )) traces
634
  )
635
     
636
(* Merges elements of graph [g2] into graph [g1] *)
637
let merge_with g1 g2 =
638
  begin
639
    IdentDepGraph.iter_vertex (fun v -> IdentDepGraph.add_vertex g1 v) g2;
640
    IdentDepGraph.iter_edges (fun s t -> IdentDepGraph.add_edge g1 s t) g2
641
  end
642

    
643
let world = "!!_world"
644

    
645
let add_external_dependency outputs mems g =
646
  begin
647
    IdentDepGraph.add_vertex g world;
648
    ISet.iter (fun o -> IdentDepGraph.add_edge g world o) outputs;
649
    ISet.iter (fun m -> IdentDepGraph.add_edge g world m) mems;
650
  end
651

    
652
(* Takes a node and return a pair (node', graph) where node' is node
653
   rebuilt with the equations enriched with new ones introduced to
654
   "break cycles" *)
655
let global_dependency node =
656
  let mems = ExprDep.node_memory_variables node in
657
  let inputs =
658
    ISet.union
659
      (ExprDep.node_input_variables node)
660
      (ExprDep.node_constant_variables node) in
661
  let outputs = ExprDep.node_output_variables node in
662
  let node_vars = ExprDep.node_variables node in
663
  let (g_non_mems, g_mems) = ExprDep.dependence_graph mems inputs node_vars node in
664
  (*Format.eprintf "g_non_mems: %a" pp_dep_graph g_non_mems;
665
    Format.eprintf "g_mems: %a" pp_dep_graph g_mems;*)
666
  try
667
    CycleDetection.check_cycles g_non_mems;
668
    let (vdecls', eqs', g_mems') = CycleDetection.break_cycles node mems g_mems in
669
    (*Format.eprintf "g_mems': %a" pp_dep_graph g_mems';*)
670
    begin
671
      merge_with g_non_mems g_mems';
672
      add_external_dependency outputs mems g_non_mems;
673
      { node with node_stmts = List.map (fun eq -> Eq eq) eqs'; node_locals = vdecls'@node.node_locals }, 
674
      g_non_mems
675
    end
676
  with Error (DataCycle _ as exc) -> (
677
      raise (Error (exc))
678
  )
679

    
680
(* A module to sort dependencies among local variables when relying on clocked declarations *)
681
module VarClockDep =
682
struct
683
  let rec get_clock_dep ck =
684
    match ck.Clocks.cdesc with
685
    | Clocks.Con (ck ,c ,l) -> l::(get_clock_dep ck)
686
    | Clocks.Clink ck' 
687
    | Clocks.Ccarrying (_, ck') -> get_clock_dep ck'
688
    | _ -> []
689
      
690
  let sort locals =
691
    let g = new_graph () in
692
    let g = List.fold_left (
693
      fun g var_decl ->
694
	let deps = get_clock_dep var_decl.var_clock in
695
	add_edges [var_decl.var_id] deps g
696
    ) g locals
697
    in
698
    let sorted, no_deps =
699
      TopologicalDepGraph.fold (fun vid (accu, remaining) -> (
700
	let select v = v.var_id = vid in
701
	let selected, not_selected = List.partition select remaining in
702
	selected@accu, not_selected
703
      )) g ([],locals)
704
    in
705
    no_deps @ sorted
706
    
707
end
708
  
709
(* Local Variables: *)
710
(* compile-command:"make -C .." *)
711
(* End: *)