lustrec / src / scheduling.ml @ d4807c3d
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(*  

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* SchedMCore  A MultiCore Scheduling Framework 
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* Copyright (C) 20092013, ONERA, Toulouse, FRANCE  LIFL, Lille, FRANCE 
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* Copyright (C) 20122013, INPT, Toulouse, FRANCE 
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* 
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* This file is part of Prelude 
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* 
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* Prelude is free software; you can redistribute it and/or 
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* modify it under the terms of the GNU Lesser General Public License 
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* as published by the Free Software Foundation ; either version 2 of 
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* the License, or (at your option) any later version. 
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* 
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* Prelude is distributed in the hope that it will be useful, but 
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* WITHOUT ANY WARRANTY ; without even the implied warranty of 
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 
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* Lesser General Public License for more details. 
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* 
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* You should have received a copy of the GNU Lesser General Public 
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* License along with this program ; if not, write to the Free Software 
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 021111307 
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* USA 
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* *) 
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(* This module is used for the lustre to C compiler *) 
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open Utils 
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open LustreSpec 
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open Corelang 
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open Graph 
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open Causality 
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(* Topological sort with a priority for variables belonging in the same equation lhs. 
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For variables still unrelated, standard compare is used to choose the minimal element. 
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This priority is used since it helps a lot in factorizing generated code. 
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In the following functions: 
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 [eq_equiv] is the equivalence relation between vars of the same equation lhs 
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 [g] the (imperative) graph to be topologically sorted 
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 [pending] is the set of unsorted root variables so far, equivalent to the last sorted var 
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 [frontier] is the set of unsorted root variables so far, not belonging in [pending] 
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 [sort] is the resulting topological order 
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*) 
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(* Adds successors of [v] in graph [g] in [pending] or [frontier] sets, wrt [eq_equiv], 
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then removes [v] from [g] 
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*) 
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let add_successors eq_equiv g v pending frontier = 
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let succs_v = IdentDepGraph.succ g v in 
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begin 
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IdentDepGraph.remove_vertex g v; 
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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; 
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end 
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(* Chooses the next var to be sorted, taking priority into account. 
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Modifies [pending] and [frontier] accordingly. 
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*) 
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let next_element eq_equiv g sort pending frontier = 
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begin 
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if ISet.is_empty !pending 
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then 
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begin 
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let choice = ISet.min_elt !frontier in 
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(*Format.eprintf "1> %s@." choice;*) 
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frontier := ISet.remove choice !frontier; 
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let (p, f) = ISet.partition (eq_equiv choice) !frontier in 
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pending := p; 
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frontier := f; 
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add_successors eq_equiv g choice pending frontier; 
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if not (ExprDep.is_instance_var choice) then sort := choice :: !sort 
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end 
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else 
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begin 
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let choice = ISet.min_elt !pending in 
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(*Format.eprintf "2> %s@." choice;*) 
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pending := ISet.remove choice !pending; 
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add_successors eq_equiv g choice pending frontier; 
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if not (ExprDep.is_instance_var choice) then sort := choice :: !sort 
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end 
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end 
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(* Topological sort of dependency graph [g], with priority. 
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*) 
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let topological_sort eq_equiv g = 
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let roots = graph_roots g in 
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assert (roots <> []); 
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let frontier = ref (List.fold_right ISet.add roots ISet.empty) in 
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let pending = ref ISet.empty in 
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let sorted = ref [] in 
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begin 
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while not (ISet.is_empty !frontier && ISet.is_empty !pending) 
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do 
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(*Format.eprintf "frontier = {%a}, pending = {%a}@." 
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(fun fmt > ISet.iter (fun e > Format.pp_print_string fmt e)) !frontier 
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(fun fmt > ISet.iter (fun e > Format.pp_print_string fmt e)) !pending;*) 
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next_element eq_equiv g sorted pending frontier; 
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done; 
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IdentDepGraph.clear g; 
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!sorted 
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end 
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let schedule_node n = 
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try 
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let eq_equiv = ExprDep.node_eq_equiv n in 
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let eq_equiv v1 v2 = 
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try 
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Hashtbl.find eq_equiv v1 = Hashtbl.find eq_equiv v2 
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with Not_found > false in 
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let n', g = global_dependency n in 
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Log.report ~level:5 (fun fmt > Format.eprintf "dependency graph for node %s: %a" n'.node_id pp_dep_graph g); 
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let gg = IdentDepGraph.copy g in 
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let sort = topological_sort eq_equiv g in 
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let death = Liveness.death_table n gg sort in 
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Log.report ~level:5 (fun fmt > Format.eprintf "death table for node %s: %a" n'.node_id Liveness.pp_death_table death); 
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let reuse = Liveness.reuse_policy n sort death in 
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Log.report ~level:5 (fun fmt > Format.eprintf "reuse policy for node %s: %a" n'.node_id Liveness.pp_reuse_policy reuse); 
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n', sort 
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(* let sorted = TopologicalDepGraph.fold (fun x res > if ExprDep.is_instance_var x then res else x::res) g []*) 
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with (Causality.Cycle v) as exc > 
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pp_error Format.err_formatter v; 
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raise exc 
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(* Local Variables: *) 
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(* compilecommand:"make C .." *) 
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(* End: *) 