CristalCaveGem » LustreC

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

(*                                                                  *)

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

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

(*                                                                  *)

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

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

(*  version 2.1.                                                    *)

(*                                                                  *)

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

open Utils

open LustreSpec

open Corelang

open Graph

open Causality

type schedule_report =

{

  (* a schedule computed wrt the dependency graph *)

  schedule : ident list list;

  (* the set of unused variables (no output or mem depends on them) *)

  unused_vars : ISet.t;

  (* the table mapping each local var to its in-degree *)

  fanin_table : (ident, int) Hashtbl.t;

  (* the table mapping each assignment to a reusable variable *)

  reuse_table : (ident, var_decl) Hashtbl.t

}

(* Topological sort with a priority for variables belonging in the same equation lhs.

   For variables still unrelated, standard compare is used to choose the minimal element.

   This priority is used since it helps a lot in factorizing generated code.

   Moreover, the dependency graph is browsed in a depth-first manner whenever possible,

   to improve the behavior of optimization algorithms applied in forthcoming compilation steps. 

   In the following functions:

   - [eq_equiv] is the equivalence relation between vars of the same equation lhs

   - [g] the (imperative) graph to be topologically sorted

   - [pending] is the set of unsorted root variables so far, equivalent to the last sorted var

   - [frontier] is the set of unsorted root variables so far, not belonging in [pending]

   - [sort] is the resulting topological order

*)

(* Checks whether the currently scheduled variable [choice]

   is an output of a call, possibly among others *)

let is_call_output choice g =

 List.exists ExprDep.is_instance_var (IdentDepGraph.succ g choice)

(* Adds successors of [v] in graph [g] in [pending] or [frontier] sets, wrt [eq_equiv],

   then removes [v] from [g] 

*)

let add_successors eq_equiv g v pending frontier =

  let succs_v = IdentDepGraph.succ g v in

  begin

    IdentDepGraph.remove_vertex g v;

    List.iter 

      (fun v' -> 

	if is_graph_root v' g then 

	  (if eq_equiv v v' then 

	      pending := ISet.add v' !pending 

	   else

	      frontier := ISet.add v' !frontier)

      ) succs_v;

  end

(* Chooses the next var to be sorted, taking priority into account.

   Modifies [pending] and [frontier] accordingly.

*)

let next_element eq_equiv g sort call pending frontier =

  begin

    if ISet.is_empty !pending

    then

      begin

	let choice = ISet.min_elt !frontier in

      (*Format.eprintf "-1-> %s@." choice;*)

	frontier := ISet.remove choice !frontier;

	let (p, f) = ISet.partition (eq_equiv choice) !frontier in

	pending := p;

	frontier := f;

	call := is_call_output choice g;

	add_successors eq_equiv g choice pending frontier;

	if not (ExprDep.is_ghost_var choice)

	then sort := [choice] :: !sort

      end

    else

      begin

	let choice = ISet.min_elt !pending in

      (*Format.eprintf "-2-> %s@." choice;*)

	pending := ISet.remove choice !pending;

	add_successors eq_equiv g choice pending frontier;

	if not (ExprDep.is_ghost_var choice)

	then sort := (if !call

		      then (choice :: List.hd !sort) :: List.tl !sort

		      else [choice] :: !sort)

      end

  end

(* Topological sort of dependency graph [g], with priority.

 *)

let topological_sort eq_equiv g =

  let roots = graph_roots g in

  assert (roots <> []);

  let call = ref false in

  let frontier = ref (List.fold_right ISet.add roots ISet.empty) in

  let pending = ref ISet.empty in

  let sorted = ref [] in

  begin

    while not (ISet.is_empty !frontier && ISet.is_empty !pending)

    do

      (*Format.eprintf "frontier = {%a}, pending = {%a}@."

	(fun fmt -> ISet.iter (fun e -> Format.pp_print_string fmt e)) !frontier

	(fun fmt -> ISet.iter (fun e -> Format.pp_print_string fmt e)) !pending;*)

      next_element eq_equiv g sorted call pending frontier;

    done;

    IdentDepGraph.clear g;

    !sorted

  end

(* Filters out normalization variables and renames instance variables to keep things readable,

   in a case of a dependency error *)

let filter_original n vl =

 List.fold_right (fun v res ->

   if ExprDep.is_instance_var v then Format.sprintf "node %s" (ExprDep.undo_instance_var v) :: res else

   let vdecl = get_node_var v n in

   if vdecl.var_orig then v :: res else res) vl []

let schedule_node n =

  let node_vars = get_node_vars n in

  try

    let eq_equiv = ExprDep.node_eq_equiv n in

    let eq_equiv v1 v2 =

      try

	Hashtbl.find eq_equiv v1 = Hashtbl.find eq_equiv v2

      with Not_found -> false in

    let n', g = global_dependency n in

    Log.report ~level:5 

      (fun fmt -> 

	Format.fprintf fmt

	  "dependency graph for node %s: %a" 

	  n'.node_id

	  pp_dep_graph g

      );

    (* TODO X: extend the graph with inputs (adapt the causality analysis to deal with inputs

     compute: coi predecessors of outputs

     warning (no modification) when memories are non used (do not impact output) or when inputs are not used (do not impact output)

       DONE !

     *)

    let gg = IdentDepGraph.copy g in

    let sort = topological_sort eq_equiv g in

    let unused = Liveness.compute_unused_variables n gg in

    let fanin = Liveness.compute_fanin n gg in

    let disjoint = Disjunction.clock_disjoint_map node_vars in

    Log.report ~level:3 

      (fun fmt -> 

	Format.fprintf fmt

	  "clock disjoint map for node %s: %a" 

	  n'.node_id

	  Disjunction.pp_disjoint_map disjoint

      );

    let reuse = Liveness.compute_reuse_policy n sort disjoint gg in

    n', { schedule = sort; unused_vars = unused; fanin_table = fanin; reuse_table = reuse }

  with (Causality.Cycle vl) as exc ->

    let vl = filter_original n vl in

    pp_error Format.err_formatter vl;

    raise exc

let schedule_prog prog =

  List.fold_right (

    fun top_decl (accu_prog, sch_map)  ->

      match top_decl.top_decl_desc with

	| Node nd -> 

	  let nd', report = schedule_node nd in

	  {top_decl with top_decl_desc = Node nd'}::accu_prog, 

	  IMap.add nd.node_id report sch_map

	| _ -> top_decl::accu_prog, sch_map

    ) 

    prog

    ([],IMap.empty)

let pp_eq_schedule fmt vl =

  match vl with

  | []  -> assert false

  | [v] -> Format.fprintf fmt "%s" v

  | _   -> Format.fprintf fmt "(%a)" (fprintf_list ~sep:" , " (fun fmt v -> Format.fprintf fmt "%s" v)) vl

let pp_schedule fmt node_schs =

 IMap.iter

   (fun nd report ->

     Format.fprintf fmt "%s schedule: %a@."

       nd

       (fprintf_list ~sep:" ; " pp_eq_schedule) report.schedule)

   node_schs

let pp_fanin_table fmt node_schs =

  IMap.iter

    (fun nd report ->

      Format.fprintf fmt "%s : %a" nd Liveness.pp_fanin report.fanin_table)

    node_schs

let pp_warning_unused fmt node_schs =

 IMap.iter

   (fun nd report ->

     let unused = report.unused_vars in

     if not (ISet.is_empty unused)

     then

       let nd = match (Corelang.node_from_name nd).top_decl_desc with Node nd -> nd | _ -> assert false in

       ISet.iter

	 (fun u ->

	   let vu = get_node_var u nd in

	   if vu.var_orig

	   then Format.fprintf fmt "Warning: variable '%s' seems unused@.%a@." u Location.pp_loc vu.var_loc)

	 unused

   )

   node_schs

(* Local Variables: *)

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

(* End: *)