Project

General

Profile

Statistics
| Branch: | Tag: | Revision:

lustrec / src / causality.ml @ e7cc5186

History | View | Annotate | Download (22.5 KB)

1
(********************************************************************)
2
(*                                                                  *)
3
(*  The LustreC compiler toolset   /  The LustreC Development Team  *)
4
(*  Copyright 2012 -    --   ONERA - CNRS - INPT - LIFL             *)
5
(*                                                                  *)
6
(*  LustreC is free software, distributed WITHOUT ANY WARRANTY      *)
7
(*  under the terms of the GNU Lesser General Public License        *)
8
(*  version 2.1.                                                    *)
9
(*                                                                  *) 
10
(*  This file was originally from the Prelude compiler              *)
11
(*                                                                  *) 
12
(********************************************************************)
13

    
14

    
15
(** Simple modular syntactic causality analysis. Can reject correct
16
    programs, especially if the program is not flattened first. *)
17
open Utils
18
open LustreSpec
19
open Corelang
20
open Graph
21

    
22

    
23
type identified_call = eq * tag
24
type error =
25
  | DataCycle of ident list list (* multiple failed partitions at once *) 
26
  | NodeCycle of ident list
27

    
28
exception Error of error
29

    
30

    
31
module IdentDepGraph = Graph.Imperative.Digraph.ConcreteBidirectional (IdentModule)
32
(*module DotGraph = Graphviz.Dot (IdentDepGraph)*)
33
module Bfs = Traverse.Bfs (IdentDepGraph)
34
  
35
(* Dependency of mem variables on mem variables is cut off 
36
   by duplication of some mem vars into local node vars.
37
   Thus, cylic dependency errors may only arise between no-mem vars.
38
   non-mem variables are:
39
   - constants/inputs: not needed for causality/scheduling, needed only for detecting useless vars
40
   - read mems (fake vars): same remark as above.
41
   - outputs: decoupled from mems, if necessary
42
   - locals
43
   - instance vars (fake vars): simplify causality analysis
44
   
45
   global constants are not part of the dependency graph.
46
   
47
   no_mem' = combinational(no_mem, mem);
48
   => (mem -> no_mem' -> no_mem)
49

    
50
   mem' = pre(no_mem, mem);
51
   => (mem' -> no_mem), (mem -> mem')
52
   
53
   Global roadmap:
54
   - compute two dep graphs g (non-mem/non-mem&mem) and g' (mem/mem)
55
   - check cycles in g (a cycle means a dependency error)
56
   - break cycles in g' (it's legal !):
57
     - check cycles in g'
58
     - if any, introduce aux var to break cycle, then start afresh
59
   - insert g' into g
60
   - return g
61
*)
62

    
63
(* Tests whether [v] is a root of graph [g], i.e. a source *)
64
let is_graph_root v g =
65
  IdentDepGraph.in_degree g v = 0
66

    
67
(* Computes the set of graph roots, i.e. the sources of acyclic graph [g] *)
68
let graph_roots g =
69
  IdentDepGraph.fold_vertex
70
    (fun v roots -> if is_graph_root v g then v::roots else roots)
71
    g []
72

    
73
let add_edges src tgt g =
74
 (*List.iter (fun s -> List.iter (fun t -> Format.eprintf "add %s -> %s@." s t) tgt) src;*)
75
  List.iter
76
    (fun s ->
77
      List.iter
78
	(fun t -> IdentDepGraph.add_edge g s t)
79
	tgt)
80
    src;
81
  g
82

    
83
let add_vertices vtc g =
84
 (*List.iter (fun t -> Format.eprintf "add %s@." t) vtc;*)
85
  List.iter (fun v -> IdentDepGraph.add_vertex g v) vtc;
86
  g
87

    
88
let new_graph () =
89
  IdentDepGraph.create ()
90

    
91
module ExprDep = struct
92

    
93
  let instance_var_cpt = ref 0
94

    
95
(* read vars represent input/mem read-only vars,
96
   they are not part of the program/schedule,
97
   as they are not assigned,
98
   but used to compute useless inputs/mems.
99
   a mem read var represents a mem at the beginning of a cycle  *)
100
  let mk_read_var id =
101
    Format.sprintf "#%s" id
102

    
103
(* instance vars represent node instance calls,
104
   they are not part of the program/schedule,
105
   but used to simplify causality analysis
106
*)
107
  let mk_instance_var id =
108
    incr instance_var_cpt; Format.sprintf "!%s_%d" id !instance_var_cpt
109

    
110
  let is_read_var v = v.[0] = '#'
111

    
112
  let is_instance_var v = v.[0] = '!'
113

    
114
  let is_ghost_var v = is_instance_var v || is_read_var v
115

    
116
  let undo_read_var id =
117
    assert (is_read_var id);
118
    String.sub id 1 (String.length id - 1)
119

    
120
  let undo_instance_var id =
121
    assert (is_instance_var id);
122
    String.sub id 1 (String.length id - 1)
123

    
124
  let eq_memory_variables mems eq =
125
    let rec match_mem lhs rhs mems =
126
      match rhs.expr_desc with
127
      | Expr_fby _
128
      | Expr_pre _    -> List.fold_right ISet.add lhs mems
129
      | Expr_tuple tl -> 
130
	 let lhs' = (transpose_list [lhs]) in
131
	 List.fold_right2 match_mem lhs' tl mems
132
      | _             -> mems in
133
    match_mem eq.eq_lhs eq.eq_rhs mems
134

    
135
  let node_memory_variables nd =
136
    List.fold_left eq_memory_variables ISet.empty (get_node_eqs nd)
137

    
138
  let node_input_variables nd =
139
    List.fold_left (fun inputs v -> ISet.add v.var_id inputs) ISet.empty nd.node_inputs
140

    
141
  let node_local_variables nd =
142
    List.fold_left (fun locals v -> ISet.add v.var_id locals) ISet.empty nd.node_locals
143

    
144
  let node_constant_variables nd =
145
    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
146

    
147
  let node_output_variables nd =
148
    List.fold_left (fun outputs v -> ISet.add v.var_id outputs) ISet.empty nd.node_outputs
149

    
150
  let node_auxiliary_variables nd =
151
    ISet.diff (node_local_variables nd) (node_memory_variables nd)
152

    
153
  let node_variables nd =
154
    let inputs = node_input_variables nd in
155
    let inoutputs = List.fold_left (fun inoutputs v -> ISet.add v.var_id inoutputs) inputs nd.node_outputs in
156
    List.fold_left (fun vars v -> ISet.add v.var_id vars) inoutputs nd.node_locals
157

    
158
(* computes the equivalence relation relating variables 
159
   in the same equation lhs, under the form of a table 
160
   of class representatives *)
161
  let node_eq_equiv nd =
162
    let eq_equiv = Hashtbl.create 23 in
163
    List.iter (fun eq ->
164
      let first = List.hd eq.eq_lhs in
165
      List.iter (fun v -> Hashtbl.add eq_equiv v first) eq.eq_lhs
166
    )
167
      (get_node_eqs nd);
168
    eq_equiv
169

    
170
(* Create a tuple of right dimension, according to [expr] type, *)
171
(* filled with variable [v] *)
172
  let adjust_tuple v expr =
173
    match expr.expr_type.Types.tdesc with
174
    | Types.Ttuple tl -> duplicate v (List.length tl)
175
    | _         -> [v]
176

    
177

    
178
  (* Add dependencies from lhs to rhs in [g, g'], *)
179
  (* no-mem/no-mem and mem/no-mem in g            *)
180
  (* mem/mem in g'                                *)
181
  (*     match (lhs_is_mem, ISet.mem x mems) with
182
	 | (false, true ) -> (add_edges [x] lhs g,
183
	 g')
184
	 | (false, false) -> (add_edges lhs [x] g,
185
	 g')
186
	 | (true , false) -> (add_edges lhs [x] g,
187
	 g')
188
	 | (true , true ) -> (g,
189
	 add_edges [x] lhs g')
190
  *)
191
  let add_eq_dependencies mems inputs node_vars eq (g, g') =
192
    let add_var lhs_is_mem lhs x (g, g') =
193
      if is_instance_var x || ISet.mem x node_vars then
194
	if ISet.mem x mems
195
	then
196
	  let g = add_edges lhs [mk_read_var x] g in
197
	  if lhs_is_mem
198
	  then
199
	    (g, add_edges [x] lhs g')
200
	  else
201
	    (add_edges [x] lhs g, g')
202
	else
203
	  let x = if ISet.mem x inputs then mk_read_var x else x in
204
	  (add_edges lhs [x] g, g')
205
      else (add_edges lhs [mk_read_var x] g, g') (* x is a global constant, treated as a read var *)
206
    in
207
  (* Add dependencies from [lhs] to rhs clock [ck]. *)
208
    let rec add_clock lhs_is_mem lhs ck g =
209
    (*Format.eprintf "add_clock %a@." Clocks.print_ck ck;*)
210
      match (Clocks.repr ck).Clocks.cdesc with
211
      | Clocks.Con (ck', cr, _)   -> add_var lhs_is_mem lhs (Clocks.const_of_carrier cr) (add_clock lhs_is_mem lhs ck' g)
212
      | Clocks.Ccarrying (_, ck') -> add_clock lhs_is_mem lhs ck' g
213
      | _                         -> g 
214
    in
215
    let rec add_dep lhs_is_mem lhs rhs g =
216
    (* Add mashup dependencies for a user-defined node instance [lhs] = [f]([e]) *)
217
    (* i.e every input is connected to every output, through a ghost var *)
218
      let mashup_appl_dependencies f e g =
219
	let f_var = mk_instance_var (Format.sprintf "%s_%d" f eq.eq_loc.Location.loc_start.Lexing.pos_lnum) in
220
	List.fold_right (fun rhs -> add_dep lhs_is_mem (adjust_tuple f_var rhs) rhs)
221
	  (expr_list_of_expr e) (add_var lhs_is_mem lhs f_var g) 
222
      in
223
      match rhs.expr_desc with
224
      | Expr_const _    -> g
225
      | Expr_fby (e1, e2)  -> add_dep true lhs e2 (add_dep false lhs e1 g)
226
      | Expr_pre e      -> add_dep true lhs e g
227
      | Expr_ident x -> add_var lhs_is_mem lhs x (add_clock lhs_is_mem lhs rhs.expr_clock g)
228
      | Expr_access (e1, d)
229
      | Expr_power (e1, d) -> add_dep lhs_is_mem lhs e1 (add_dep lhs_is_mem lhs (expr_of_dimension d) g)
230
      | Expr_array a -> List.fold_right (add_dep lhs_is_mem lhs) a g
231
      | Expr_tuple t -> List.fold_right2 (fun l r -> add_dep lhs_is_mem [l] r) lhs t g
232
      | 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)
233
      | 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))
234
      | Expr_arrow (e1, e2)  -> add_dep lhs_is_mem lhs e2 (add_dep lhs_is_mem lhs e1 g)
235
      | Expr_when  (e, c, _)  -> add_dep lhs_is_mem lhs e (add_var lhs_is_mem lhs c g)
236
      | Expr_appl (f, e, None) ->
237
	 if Basic_library.is_expr_internal_fun rhs
238
      (* tuple component-wise dependency for internal operators *)
239
	 then
240
	   List.fold_right (add_dep lhs_is_mem lhs) (expr_list_of_expr e) g
241
      (* mashed up dependency for user-defined operators *)
242
	 else
243
	   mashup_appl_dependencies f e g
244
      | Expr_appl (f, e, Some c) ->
245
	 mashup_appl_dependencies f e (add_dep lhs_is_mem lhs c g)
246
    in
247
    let g =
248
      List.fold_left
249
	(fun g lhs ->
250
	  if ISet.mem lhs mems then
251
	    add_vertices [lhs; mk_read_var lhs] g
252
	  else
253
	    add_vertices [lhs] g
254
	)
255
	g eq.eq_lhs
256
    in
257
    add_dep false eq.eq_lhs eq.eq_rhs (g, g')
258
      
259

    
260
  (* Returns the dependence graph for node [n] *)
261
  let dependence_graph mems inputs node_vars n =
262
    instance_var_cpt := 0;
263
    let g = new_graph (), new_graph () in
264
    (* Basic dependencies *)
265
    let g = List.fold_right (add_eq_dependencies mems inputs node_vars) (get_node_eqs n) g in
266
    (* TODO Xavier: un essai ci dessous. Ca n'a pas l'air de résoudre le pb. Il
267
       faut imposer que les outputs dépendent des asserts pour identifier que les
268
       fcn calls des asserts sont évalués avant le noeuds *)
269
    
270
    (* (\* In order to introduce dependencies between assert expressions and the node, *)
271
    (*    we build an artificial dependency between node output and each assert *)
272
    (*    expr. While these are not valid equations, they should properly propage in *)
273
    (*    function add_eq_dependencies *\) *)
274
    (* let g = *)
275
    (*   let output_vars_as_lhs = ISet.elements (node_output_variables n) in *)
276
    (*   List.fold_left (fun g ae -> *)
277
    (*     let fake_eq = mkeq Location.dummy_loc (output_vars_as_lhs, ae.assert_expr) in *)
278
    (*   add_eq_dependencies mems inputs node_vars fake_eq g *)
279
    (* ) g n.node_asserts in  *)
280
    g
281

    
282
end
283

    
284
module NodeDep = struct
285

    
286
  module ExprModule =
287
  struct
288
    type t = expr
289
    let compare = compare
290
    let hash n = Hashtbl.hash n
291
    let equal n1 n2 = n1 = n2
292
  end
293

    
294
  module ESet = Set.Make(ExprModule)
295

    
296
  let rec get_expr_calls prednode expr = 
297
    match expr.expr_desc with
298
    | Expr_const _ 
299
    | Expr_ident _ -> ESet.empty
300
    | Expr_access (e, _)
301
    | Expr_power (e, _) -> get_expr_calls prednode e
302
    | Expr_array t
303
    | Expr_tuple t -> List.fold_right (fun x set -> ESet.union (get_expr_calls prednode x) set) t ESet.empty
304
    | Expr_merge (_,hl) -> List.fold_right (fun (_,h) set -> ESet.union (get_expr_calls prednode h) set) hl ESet.empty
305
    | Expr_fby (e1,e2)
306
    | Expr_arrow (e1,e2) -> ESet.union (get_expr_calls prednode e1) (get_expr_calls prednode e2)
307
    | Expr_ite   (c, t, e) -> ESet.union (get_expr_calls prednode c) (ESet.union (get_expr_calls prednode t) (get_expr_calls prednode e))
308
    | Expr_pre e 
309
    | Expr_when (e,_,_) -> get_expr_calls prednode e
310
    | Expr_appl (id,e, _) ->
311
       if not (Basic_library.is_expr_internal_fun expr) && prednode id
312
       then ESet.add expr (get_expr_calls prednode e)
313
       else (get_expr_calls prednode e)
314

    
315
  let get_callee expr =
316
    match expr.expr_desc with
317
    | Expr_appl (id, args, _) -> Some (id, expr_list_of_expr args)
318
    | _ -> None
319

    
320
  let get_calls prednode eqs =
321
    let deps =
322
      List.fold_left 
323
	(fun accu eq -> ESet.union accu (get_expr_calls prednode eq.eq_rhs))
324
	ESet.empty
325
	eqs in
326
    ESet.elements deps
327

    
328
  let dependence_graph prog =
329
    let g = new_graph () in
330
    let g = List.fold_right 
331
      (fun td accu -> (* for each node we add its dependencies *)
332
	match td.top_decl_desc with 
333
	| Node nd ->
334
	  (*Format.eprintf "Computing deps of node %s@.@?" nd.node_id; *)
335
	   let accu = add_vertices [nd.node_id] accu in
336
	   let deps = List.map
337
	     (fun e -> fst (desome (get_callee e)))
338
	     (get_calls (fun _ -> true) (get_node_eqs nd)) 
339
	   in
340
	     (* Adding assert expressions deps *)
341
	   let deps_asserts =
342
	     let prednode = (fun _ -> true) in (* what is this about? *)
343
	     List.map
344
	       (fun e -> fst (desome (get_callee e)))
345
 	       (ESet.elements
346
		  (List.fold_left
347
		     (fun accu assert_expr -> ESet.union accu (get_expr_calls prednode assert_expr))
348
		     ESet.empty
349
		     (List.map (fun _assert -> _assert.assert_expr) nd.node_asserts)
350
		  )
351
	       )
352
      	   in
353
	   (*Format.eprintf "%a@.@?" (Utils.fprintf_list ~sep:"@." Format.pp_print_string) deps; *)
354
	   add_edges [nd.node_id] (deps@deps_asserts) accu
355
	| _ -> assert false (* should not happen *)
356
	   
357
      ) prog g in
358
    g   
359

    
360
  (* keep subgraph of [gr] consisting of nodes accessible from node [v] *)
361
  let slice_graph gr v =
362
    begin
363
      let gr' = new_graph () in
364
      IdentDepGraph.add_vertex gr' v;
365
      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;
366
      gr'
367
    end
368
      
369
  let rec filter_static_inputs inputs args =
370
    match inputs, args with
371
    | []   , [] -> []
372
    | 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
373
    | _ -> assert false
374

    
375
  let compute_generic_calls prog =
376
    List.iter
377
      (fun td ->
378
	match td.top_decl_desc with 
379
	| Node nd ->
380
	   let prednode n = is_generic_node (Hashtbl.find node_table n) in
381
	   nd.node_gencalls <- get_calls prednode (get_node_eqs nd)
382
	| _ -> ()
383
	   
384
      ) prog
385

    
386
end
387

    
388

    
389
module CycleDetection = struct
390

    
391
  (* ---- Look for cycles in a dependency graph *)
392
  module Cycles = Graph.Components.Make (IdentDepGraph)
393

    
394
  let mk_copy_var n id =
395
    let used name =
396
      (List.exists (fun v -> v.var_id = name) n.node_locals)
397
      || (List.exists (fun v -> v.var_id = name) n.node_inputs)
398
      || (List.exists (fun v -> v.var_id = name) n.node_outputs)
399
    in mk_new_name used id
400

    
401
  let mk_copy_eq n var =
402
    let var_decl = get_node_var var n in
403
    let cp_var = mk_copy_var n var in
404
    let expr =
405
      { expr_tag = Utils.new_tag ();
406
	expr_desc = Expr_ident var;
407
	expr_type = var_decl.var_type;
408
	expr_clock = var_decl.var_clock;
409
	expr_delay = Delay.new_var ();
410
	expr_annot = None;
411
	expr_loc = var_decl.var_loc } in
412
    { var_decl with var_id = cp_var; var_orig = false },
413
    mkeq var_decl.var_loc ([cp_var], expr)
414

    
415
  let wrong_partition g partition =
416
    match partition with
417
    | [id]    -> IdentDepGraph.mem_edge g id id
418
    | _::_::_ -> true
419
    | []      -> assert false
420

    
421
  (* Checks that the dependency graph [g] does not contain a cycle. Raises
422
     [Cycle partition] if the succession of dependencies [partition] forms a cycle *)
423
  let check_cycles g =
424
    let scc_l = Cycles.scc_list g in
425
    let algebraic_loops = List.filter (wrong_partition g) scc_l in
426
    if List.length algebraic_loops > 0 then
427
      raise (Error (DataCycle algebraic_loops))
428
	(* We extract a hint to resolve the cycle: for each variable in the cycle
429
	   which is defined by a call, we return the name of the node call and
430
	   its specific id *)
431

    
432
  (* Creates the sub-graph of [g] restricted to vertices and edges in partition *)
433
  let copy_partition g partition =
434
    let copy_g = IdentDepGraph.create () in
435
    IdentDepGraph.iter_edges
436
      (fun src tgt ->
437
	if List.mem src partition && List.mem tgt partition
438
	then IdentDepGraph.add_edge copy_g src tgt)
439
      g
440

    
441
      
442
  (* Breaks dependency cycles in a graph [g] by inserting aux variables.
443
     [head] is a head of a non-trivial scc of [g]. 
444
     In Lustre, this is legal only for mem/mem cycles *)
445
  let break_cycle head cp_head g =
446
    let succs = IdentDepGraph.succ g head in
447
    IdentDepGraph.add_edge g head cp_head;
448
    IdentDepGraph.add_edge g cp_head (ExprDep.mk_read_var head);
449
    List.iter
450
      (fun s ->
451
	IdentDepGraph.remove_edge g head s;
452
	IdentDepGraph.add_edge    g s cp_head)
453
      succs
454

    
455
  (* Breaks cycles of the dependency graph [g] of memory variables [mems]
456
     belonging in node [node]. Returns:
457
     - a list of new auxiliary variable declarations
458
     - a list of new equations
459
     - a modified acyclic version of [g]
460
  *)
461
  let break_cycles node mems g =
462
    let (mem_eqs, non_mem_eqs) = List.partition (fun eq -> List.exists (fun v -> ISet.mem v mems) eq.eq_lhs) (get_node_eqs node) in
463
    let rec break vdecls mem_eqs g =
464
      let scc_l = Cycles.scc_list g in
465
      let wrong = List.filter (wrong_partition g) scc_l in
466
      match wrong with
467
      | []              -> (vdecls, non_mem_eqs@mem_eqs, g)
468
      | [head]::_       ->
469
	 begin
470
	   IdentDepGraph.remove_edge g head head;
471
	   break vdecls mem_eqs g
472
	 end
473
      | (head::part)::_ -> 
474
	 begin
475
	   let vdecl_cp_head, cp_eq = mk_copy_eq node head in
476
	   let pvar v = List.mem v part in
477
	   let fvar v = if v = head then vdecl_cp_head.var_id else v in
478
	   let mem_eqs' = List.map (eq_replace_rhs_var pvar fvar) mem_eqs in
479
	   break_cycle head vdecl_cp_head.var_id g;
480
	   break (vdecl_cp_head::vdecls) (cp_eq::mem_eqs') g
481
	 end
482
      | _               -> assert false
483
    in break [] mem_eqs g
484

    
485
end
486

    
487
(* Module used to compute static disjunction of variables based upon their clocks. *)
488
module Disjunction =
489
struct
490
  module ClockedIdentModule =
491
  struct
492
    type t = var_decl
493
    let root_branch vdecl = Clocks.root vdecl.var_clock, Clocks.branch vdecl.var_clock
494
    let compare v1 v2 = compare (root_branch v2, v2.var_id) (root_branch v1, v1.var_id)
495
  end
496

    
497
  module CISet = Set.Make(ClockedIdentModule)
498

    
499
  (* map: var |-> list of disjoint vars, sorted in increasing branch length order,
500
     maybe removing shorter branches *)
501
  type disjoint_map = (ident, CISet.t) Hashtbl.t
502

    
503
  let pp_ciset fmt t =
504
    begin
505
      Format.fprintf fmt "{@ ";
506
      CISet.iter (fun s -> Format.fprintf fmt "%a@ " Printers.pp_var_name s) t;
507
      Format.fprintf fmt "}@."
508
    end
509

    
510
  let clock_disjoint_map vdecls =
511
    let map = Hashtbl.create 23 in
512
    begin
513
      List.iter
514
	(fun v1 -> let disj_v1 =
515
		     List.fold_left
516
		       (fun res v2 -> if Clocks.disjoint v1.var_clock v2.var_clock then CISet.add v2 res else res)
517
		       CISet.empty
518
		       vdecls in
519
		   (* disjoint vdecls are stored in increasing branch length order *)
520
		   Hashtbl.add map v1.var_id disj_v1)
521
	vdecls;
522
      (map : disjoint_map)
523
    end
524

    
525
  (* merge variables [v] and [v'] in disjunction [map]. Then:
526
     - the mapping v' becomes v' |-> (map v) inter (map v')
527
     - the mapping v |-> ... then disappears
528
     - other mappings become x |-> (map x) \ (if v in x then v else v')
529
  *)
530
  let merge_in_disjoint_map map v v' =
531
    begin
532
      Hashtbl.replace map v'.var_id (CISet.inter (Hashtbl.find map v.var_id) (Hashtbl.find map v'.var_id));
533
      Hashtbl.remove map v.var_id;
534
      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;
535
    end
536

    
537
  (* replace variable [v] by [v'] in disjunction [map].
538
     [v'] is a dead variable. Then:
539
     - the mapping v' becomes v' |-> (map v)
540
     - the mapping v |-> ... then disappears
541
     - all mappings become x |-> ((map x) \ { v}) union ({v'} if v in map x)
542
  *)
543
  let replace_in_disjoint_map map v v' =
544
    begin
545
      Hashtbl.replace map v'.var_id (Hashtbl.find map v.var_id);
546
      Hashtbl.remove  map v.var_id;
547
      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;
548
    end
549

    
550
  (* remove variable [v] in disjunction [map]. Then:
551
     - the mapping v |-> ... then disappears
552
     - all mappings become x |-> (map x) \ { v}
553
  *)
554
  let remove_in_disjoint_map map v =
555
    begin
556
      Hashtbl.remove map v.var_id;
557
      Hashtbl.iter (fun x mapx -> Hashtbl.replace map x (CISet.remove v mapx)) map;
558
    end
559

    
560
  let pp_disjoint_map fmt map =
561
    begin
562
      Format.fprintf fmt "{ /* disjoint map */@.";
563
      Hashtbl.iter (fun k v -> Format.fprintf fmt "%s # { %a }@." k (Utils.fprintf_list ~sep:", " Printers.pp_var_name) (CISet.elements v)) map;
564
      Format.fprintf fmt "}@."
565
    end
566
end
567

    
568
  
569
let pp_dep_graph fmt g =
570
  begin
571
    Format.fprintf fmt "{ /* graph */@.";
572
    IdentDepGraph.iter_edges (fun s t -> Format.fprintf fmt "%s -> %s@." s t) g;
573
    Format.fprintf fmt "}@."
574
  end
575

    
576
let pp_error fmt err =
577
  match err with
578
  | NodeCycle trace ->
579
     Format.fprintf fmt "Causality error, cyclic node calls:@   @[<v 0>%a@]@ "
580
       (fprintf_list ~sep:",@ " Format.pp_print_string) trace
581
  | DataCycle traces -> (
582
     Format.fprintf fmt "Causality error, cyclic data dependencies:@   @[<v 0>%a@]@ "
583
       (fprintf_list ~sep:";@ "
584
       (fun fmt trace ->
585
	 Format.fprintf fmt "@[<v 0>{%a}@]"
586
	   (fprintf_list ~sep:",@ " Format.pp_print_string)
587
	   trace
588
       )) traces
589
  )
590
     
591
(* Merges elements of graph [g2] into graph [g1] *)
592
let merge_with g1 g2 =
593
  begin
594
    IdentDepGraph.iter_vertex (fun v -> IdentDepGraph.add_vertex g1 v) g2;
595
    IdentDepGraph.iter_edges (fun s t -> IdentDepGraph.add_edge g1 s t) g2
596
  end
597

    
598
let world = "!!_world"
599

    
600
let add_external_dependency outputs mems g =
601
  begin
602
    IdentDepGraph.add_vertex g world;
603
    ISet.iter (fun o -> IdentDepGraph.add_edge g world o) outputs;
604
    ISet.iter (fun m -> IdentDepGraph.add_edge g world m) mems;
605
  end
606

    
607
let global_dependency node =
608
  let mems = ExprDep.node_memory_variables node in
609
  let inputs =
610
    ISet.union
611
      (ExprDep.node_input_variables node)
612
      (ExprDep.node_constant_variables node) in
613
  let outputs = ExprDep.node_output_variables node in
614
  let node_vars = ExprDep.node_variables node in
615
  let (g_non_mems, g_mems) = ExprDep.dependence_graph mems inputs node_vars node in
616
  (*Format.eprintf "g_non_mems: %a" pp_dep_graph g_non_mems;
617
    Format.eprintf "g_mems: %a" pp_dep_graph g_mems;*)
618
  try
619
    CycleDetection.check_cycles g_non_mems;
620
    let (vdecls', eqs', g_mems') = CycleDetection.break_cycles node mems g_mems in
621
    (*Format.eprintf "g_mems': %a" pp_dep_graph g_mems';*)
622
    begin
623
      merge_with g_non_mems g_mems';
624
      add_external_dependency outputs mems g_non_mems;
625
      { node with node_stmts = List.map (fun eq -> Eq eq) eqs'; node_locals = vdecls'@node.node_locals }, 
626
      g_non_mems
627
    end
628
  with Error (DataCycle _ as exc) -> (
629
      raise (Error (exc))
630
  )
631

    
632
(* Local Variables: *)
633
(* compile-command:"make -C .." *)
634
(* End: *)