heptagon/compiler/minils/transformations/schedule.ml

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(*                                                                        *)
(*  Heptagon                                                              *)
(*                                                                        *)
(*  Author : Marc Pouzet                                                  *)
(*  Organization : Demons, LRI, University of Paris-Sud, Orsay            *)
(*                                                                        *)
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(* scheduling of equations *)

(* $Id$ *)

open Misc
open Minils
open Graph
open Dep

(* possible overlapping between clocks *)
let join ck1 ck2 =
  let n1 = Vars.head ck1
  and n2 = Vars.head ck2 in
  (* C1(x1) on ... on Cn(xn) with C'1(x'1) on ... on C'k(x'k) *)
  match n1, n2 with
      [], [] -> true
    | x1 ::_, x2 ::_ when x1 = x2 -> true
    | _ -> false

let join eq1 eq2 = join (Vars.clock eq1) (Vars.clock eq2)

(* possible overlapping between nodes *)
(*let head e =
  match e with
    | Emerge(_, c_e_list) -> List.fold (fun acc e -> Vars.head (clock e) :: acc)
    | e -> [Vars.head (clock e)]

(* e1 define a pieces of control structures with *)
  (* paths on clock C1(x1) on ... on Cn(xn) ... *)
  (* e1 can be merged if *)
let n1_list = head e1 in
  let n2_list = head e2 in
*)

  
(* clever scheduling *)
let schedule eq_list =
  let rec recook = function
    | [] -> []
    | node :: node_list -> node >> (recook node_list)
	      
  and (>>) node node_list =
    try
      insert node node_list
    with
	      Not_found -> node :: node_list
	  
  and insert node = function
    | [] -> raise Not_found
    | node1 :: node_list ->
	      if linked node node1 then raise Not_found
	      else
	        try
	          node1 :: (insert node node_list)
	        with
	          | Not_found ->
		            if join (containt node) (containt node1)
	              then node :: node1 :: node_list
		            else raise Not_found in
    
  let node_list, _ = DataFlowDep.build eq_list in
  let node_list = recook (topological node_list) in
  let node_list = List.rev node_list in
  let node_list = recook node_list in
  let node_list = List.rev node_list in
    List.map containt node_list

let schedule_contract ({ c_eq = eqs } as c) =
  let eqs = schedule eqs in
  { c with c_eq = eqs }

let node ({ n_contract = contract; n_equs = eq_list } as node) =
  let contract = optional schedule_contract contract in 
  let eq_list = schedule eq_list in
  { node with n_equs = eq_list; n_contract = contract }

let program ({ p_nodes = p_node_list } as p) =
  { p with p_nodes = List.map node p_node_list }