summaryrefslogtreecommitdiff
path: root/gcc/c-family/cilk.c
blob: 3ab7f4eff0ab0a3a1396c3c341a1482f0cdae3a5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
/* This file is part of the Intel(R) Cilk(TM) Plus support
   This file contains the CilkPlus Intrinsics
   Copyright (C) 2013-2015 Free Software Foundation, Inc.
   Contributed by Balaji V. Iyer <balaji.v.iyer@intel.com>,
   Intel Corporation

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.

GCC is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "function.h"
#include "hard-reg-set.h"
#include "tree.h"
#include "c-family/c-common.h"
#include "gimple-expr.h"
#include "stringpool.h"
#include "cgraph.h"
#include "diagnostic.h"
#include "langhooks.h"
#include "gimplify.h"
#include "tree-iterator.h"
#include "tree-inline.h"
#include "toplev.h" 
#include "calls.h"
#include "cilk.h"

enum add_variable_type {
    /* Reference to previously-defined variable.  */
    ADD_READ,
    /* Definition of a new variable in inner-scope.  */
    ADD_BIND,
    /* Write to possibly previously-defined variable.  */
    ADD_WRITE
};

enum cilk_block_type {
    /* Indicates a _Cilk_spawn block.  30 was an arbitary number picked for 
       ease of debugging.  */
    CILK_BLOCK_SPAWN = 30,
    /* Indicates _Cilk_for statement block.  */
    CILK_BLOCK_FOR
};

struct wrapper_data
{
  /* Kind of function to be created.  */
  enum cilk_block_type type;
  /* Signature of helper function.  */
  tree fntype;
  /* Containing function.  */
  tree context;
  /* Disposition of all variables in the inner statement.  */
  hash_map<tree, tree> *decl_map;
  /* True if this function needs a static chain.  */
  bool nested;
  /* Arguments to be passed to wrapper function, currently a list.  */
  tree arglist;
  /* Argument types, a list.  */
  tree argtypes;
  /* Incoming parameters.  */
  tree parms;
  /* Outer BLOCK object.  */
  tree block;
};

static void extract_free_variables (tree, struct wrapper_data *,
				    enum add_variable_type);
static HOST_WIDE_INT cilk_wrapper_count;

/* Marks the CALL_EXPR or FUNCTION_DECL, FCALL, as a spawned function call
   and the current function as a spawner.  Emit error if the function call
   is outside a function or if a non function-call is spawned.  */

inline bool
cilk_set_spawn_marker (location_t loc, tree fcall)
{
  if (!current_function_decl)
    {
      error_at (loc, "%<_Cilk_spawn%> may only be used inside a function");
      return false;
    }
  else if (fcall == error_mark_node)
    /* Error reporting here is not necessary here since if FCALL is an
       error_mark_node, the function marking it as error would have reported
       it.  */
    return false; 
  else if (TREE_CODE (fcall) != CALL_EXPR
	   /* In C++, TARGET_EXPR is generated when we have an overloaded
	      '=' operator.  */
	   && TREE_CODE (fcall) != TARGET_EXPR)
    { 
      error_at (loc, "only function calls can be spawned");
      return false;
    }
  else
    {
      cfun->calls_cilk_spawn = true;
      return true;
    }
}

/* This function will output the exit conditions for a spawn call.  */

tree
create_cilk_function_exit (tree frame, bool detaches, bool needs_sync)
{
  tree epi = alloc_stmt_list ();

  if (needs_sync) 
    append_to_statement_list (build_cilk_sync (), &epi);
  tree func_ptr = build1 (ADDR_EXPR, cilk_frame_ptr_type_decl, frame);
  tree pop_frame = build_call_expr (cilk_pop_fndecl, 1, func_ptr);
  tree worker = cilk_dot (frame, CILK_TI_FRAME_WORKER, 0);
  tree current = cilk_arrow (worker, CILK_TI_WORKER_CUR, 0);
  tree parent = cilk_dot (frame, CILK_TI_FRAME_PARENT, 0);
  tree set_current = build2 (MODIFY_EXPR, void_type_node, current, parent);
  append_to_statement_list (set_current, &epi);
  append_to_statement_list (pop_frame, &epi);
  tree call = build_call_expr (cilk_leave_fndecl, 1, func_ptr);
  if (!detaches)
    {
      tree flags = cilk_dot (frame, CILK_TI_FRAME_FLAGS, false);
      tree flags_cmp_expr = fold_build2 (NE_EXPR, TREE_TYPE (flags), flags, 
					 build_int_cst (TREE_TYPE (flags), 
							CILK_FRAME_VERSION));
      call = fold_build3 (COND_EXPR, void_type_node, flags_cmp_expr,
			  call, build_empty_stmt (EXPR_LOCATION (flags)));
    }
  append_to_statement_list (call, &epi);  
  return epi;
}

/* Trying to get the correct cfun for the FUNCTION_DECL indicated by OUTER.  */

static void
pop_cfun_to (tree outer)
{
  pop_cfun ();
  current_function_decl = outer;
  gcc_assert (cfun == DECL_STRUCT_FUNCTION (current_function_decl));
  gcc_assert (cfun->decl == current_function_decl);
}

/* This function does whatever is necessary to make the compiler emit a newly 
   generated function, FNDECL.  */

static void
call_graph_add_fn (tree fndecl)
{
  const tree outer = current_function_decl;
  struct function *f = DECL_STRUCT_FUNCTION (fndecl);
  gcc_assert (TREE_CODE (fndecl) == FUNCTION_DECL);

  f->is_cilk_function = 1;
  f->curr_properties = cfun->curr_properties;
  gcc_assert (cfun == DECL_STRUCT_FUNCTION (outer)); 
  gcc_assert (cfun->decl == outer);

  push_cfun (f);
  cgraph_node::create (fndecl);
  pop_cfun_to (outer);
}

/* Return true if this is a tree which is allowed to contain a spawn as 
   operand 0.
   A spawn call may be wrapped in a series of unary operations such
   as conversions.  These conversions need not be "useless"
   to be disregarded because they are retained in the spawned
   statement.  They are bypassed only to look for a spawn
   within.
   A comparison to constant is simple enough to allow, and
   is used to convert to bool.  */

static bool
cilk_ignorable_spawn_rhs_op (tree exp)
{
  enum tree_code code = TREE_CODE (exp);
  switch (TREE_CODE_CLASS (code))
    {
    case tcc_expression:
      return code == ADDR_EXPR;
    case tcc_comparison:
      /* We need the spawn as operand 0 for now.   That's where it
	 appears in the only case we really care about, conversion
	 to bool.  */
      return (TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST);
    case tcc_unary:
    case tcc_reference:
      return true;
    default:
      return false;
    }
}

/* Helper function for walk_tree.  If *TP is a CILK_SPAWN_STMT, then unwrap
   this "wrapper."  The function returns NULL_TREE regardless.  */

static tree
unwrap_cilk_spawn_stmt (tree *tp, int *walk_subtrees, void *)
{
  if (TREE_CODE (*tp) == CILK_SPAWN_STMT)
    {
      *tp = CILK_SPAWN_FN (*tp);
      *walk_subtrees = 0;
    }
  return NULL_TREE;
}

/* Returns true when EXP is a CALL_EXPR with _Cilk_spawn in front.  Unwraps
   CILK_SPAWN_STMT wrapper from the CALL_EXPR in *EXP0 statement.  */

static bool
recognize_spawn (tree exp, tree *exp0)
{
  bool spawn_found = false;
  if (TREE_CODE (exp) == CILK_SPAWN_STMT)
    {
      /* Remove the CALL_EXPR from CILK_SPAWN_STMT wrapper.  */
      exp = CILK_SPAWN_FN (exp);
      walk_tree (exp0, unwrap_cilk_spawn_stmt, NULL, NULL);
      spawn_found = true;
    }
  /* _Cilk_spawn can't be wrapped in expression such as PLUS_EXPR.  */
  else if (contains_cilk_spawn_stmt (exp))
    error_at (EXPR_LOCATION (exp), "invalid use of %<_Cilk_spawn%>");
  return spawn_found;
}

/* Returns true if *EXP0 is a recognized form of spawn.  Recognized forms are,
   after conversion to void, a call expression at outer level or an assignment
   at outer level with the right hand side being a spawned call.
   In addition to this, it also unwraps the CILK_SPAWN_STMT cover from the
   CALL_EXPR that is being spawned.
   Note that `=' in C++ may turn into a CALL_EXPR rather than a MODIFY_EXPR.  */

bool
cilk_detect_spawn_and_unwrap (tree *exp0)
{
  tree exp = *exp0;

  if (!TREE_SIDE_EFFECTS (exp))
    return false;

  /* Strip off any conversion to void.  It does not affect whether spawn 
     is supported here.  */
  if (TREE_CODE (exp) == CONVERT_EXPR && VOID_TYPE_P (TREE_TYPE (exp)))
    exp = TREE_OPERAND (exp, 0);

  if (TREE_CODE (exp) == MODIFY_EXPR || TREE_CODE (exp) == INIT_EXPR)
    exp = TREE_OPERAND (exp, 1);

  while (cilk_ignorable_spawn_rhs_op (exp))
    exp = TREE_OPERAND (exp, 0);

  if (TREE_CODE (exp) == TARGET_EXPR)
    if (TARGET_EXPR_INITIAL (exp)
	&& TREE_CODE (TARGET_EXPR_INITIAL (exp)) != AGGR_INIT_EXPR)
      exp = TARGET_EXPR_INITIAL (exp);

  /* Happens with C++ TARGET_EXPR.  */
  if (exp == NULL_TREE)
    return false;

  while (TREE_CODE (exp) == CLEANUP_POINT_EXPR || TREE_CODE (exp) == EXPR_STMT)
    exp = TREE_OPERAND (exp, 0);
  
  /* Now we should have a CALL_EXPR with a CILK_SPAWN_STMT wrapper around 
     it, or return false.  */
  if (recognize_spawn (exp, exp0))
    return true;
  return false;
}

/* This function will build and return a FUNCTION_DECL using information 
   from *WD.  */

static tree
create_cilk_helper_decl (struct wrapper_data *wd)
{
  char name[20];
  if (wd->type == CILK_BLOCK_FOR)
    sprintf (name, "_cilk_for_" HOST_WIDE_INT_PRINT_DEC, cilk_wrapper_count++);
  else if (wd->type == CILK_BLOCK_SPAWN)
    sprintf (name, "_cilk_spn_" HOST_WIDE_INT_PRINT_DEC, cilk_wrapper_count++);
  else
    gcc_unreachable (); 
  
  clean_symbol_name (name);
  tree fndecl = build_decl (UNKNOWN_LOCATION, FUNCTION_DECL, 
			    get_identifier (name), wd->fntype);

  TREE_PUBLIC (fndecl) = 0;
  TREE_STATIC (fndecl) = 1;
  TREE_USED (fndecl) = 1;
  DECL_ARTIFICIAL (fndecl) = 0;
  DECL_IGNORED_P (fndecl) = 0;
  DECL_EXTERNAL (fndecl) = 0;

  DECL_CONTEXT (fndecl) = wd->context; 
  tree block = make_node (BLOCK);
  DECL_INITIAL (fndecl) = block;
  TREE_USED (block) = 1;
  BLOCK_SUPERCONTEXT (block) = fndecl;
  gcc_assert (!DECL_SAVED_TREE (fndecl));

  /* Inlining would defeat the purpose of this wrapper.
     Either it secretly switches stack frames or it allocates
     a stable stack frame to hold function arguments even if
     the parent stack frame is stolen.  */
  DECL_UNINLINABLE (fndecl) = 1;

  tree result_decl = build_decl (UNKNOWN_LOCATION, RESULT_DECL, NULL_TREE, 
				 void_type_node);
  DECL_ARTIFICIAL (result_decl) = 0;
  DECL_IGNORED_P (result_decl) = 1;
  DECL_CONTEXT (result_decl) = fndecl;
  DECL_RESULT (fndecl) = result_decl;
  
  return fndecl;
}

struct cilk_decls
{
  tree key;
  tree *val;
};

/* A function used by traversal to fill vector of decls for further work.  */

bool
fill_decls_vec (tree const &key0, tree *val0, auto_vec<struct cilk_decls> *v)
{
  tree t1 = key0;
  struct cilk_decls dp;

  if (DECL_P (t1))
    {
      dp.key = t1;
      dp.val = val0;
      v->safe_push (dp);
    }
  return true;
}

/* Function that actually creates necessary parm lists.  */

static void
create_parm_list (struct wrapper_data *wd, tree *val0, tree arg)
{
  tree val = *val0;
  tree parm;

  if (val == error_mark_node || val == arg)
    return;

  if (TREE_CODE (val) == PAREN_EXPR)
    {
      /* We should not reach here with a register receiver.
	 We may see a register variable modified in the
	 argument list.  Because register variables are
	 worker-local we don't need to work hard to support
	 them in code that spawns.  */
      if (VAR_P (arg) && DECL_HARD_REGISTER (arg))
	{
	  error_at (EXPR_LOCATION (arg),
		    "explicit register variable %qD may not be modified in "
		    "spawn", arg);
	  arg = null_pointer_node;
	}
      else
	arg = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (arg)), arg);

      val = TREE_OPERAND (val, 0);
      *val0 = val;
      gcc_assert (INDIRECT_REF_P (val));
      parm = TREE_OPERAND (val, 0);
      STRIP_NOPS (parm);
    }
  else
    parm = val;
  TREE_CHAIN (parm) = wd->parms;
  wd->parms = parm;
  wd->argtypes = tree_cons (NULL_TREE, TREE_TYPE (parm), wd->argtypes);
  wd->arglist = tree_cons (NULL_TREE, arg, wd->arglist);
}

/* Sorting decls in a vector.  */

static int
compare_decls (const void *a, const void *b)
{
  const struct cilk_decls *t1 = (const struct cilk_decls *) a;
  const struct cilk_decls *t2 = (const struct cilk_decls *) b;

  if (DECL_UID (t1->key) > DECL_UID (t2->key))
    return 1;
  else if (DECL_UID (t1->key) < DECL_UID (t2->key))
    return -1;
  else
    return 0;
}

/* This function is used to build a wrapper of a certain type.  */

static void
build_wrapper_type (struct wrapper_data *wd)
{
  unsigned int j;
  struct cilk_decls * c;
  auto_vec<struct cilk_decls> vd;
  wd->arglist = NULL_TREE;
  wd->parms = NULL_TREE;
  wd->argtypes = void_list_node;

  gcc_assert (wd->type != CILK_BLOCK_FOR);
  wd->decl_map->traverse<auto_vec<struct cilk_decls> *, fill_decls_vec> (&vd);
  vd.qsort (compare_decls);

  FOR_EACH_VEC_ELT (vd, j, c)
   create_parm_list (wd, c->val, c->key);

  /* Now build a function.
     Its return type is void (all side effects are via explicit parameters).
     Its parameters are WRAPPER_PARMS with type WRAPPER_TYPES.
     Actual arguments in the caller are WRAPPER_ARGS.  */
  wd->fntype = build_function_type (void_type_node, wd->argtypes);
}

/* This function checks all the CALL_EXPRs in *TP found by cilk_outline.  */

static tree
check_outlined_calls (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED, 
		      void *data)
{
  bool *throws = (bool *) data;
  tree t = *tp;
  int flags;

  if (TREE_CODE (t) != CALL_EXPR)
    return 0;
  flags = call_expr_flags (t);

  if (!(flags & ECF_NOTHROW) && flag_exceptions)
    *throws = true;
  if (flags & ECF_RETURNS_TWICE)
    error_at (EXPR_LOCATION (t), 
	      "cannot spawn call to function that returns twice");
  return 0;
}

/* Each DECL in the source code (spawned statement) is passed to this function
   once.  Each instance of the DECL is replaced with the result of this 
   function.

   The parameters of the wrapper should have been entered into the map already.
   This function only deals with variables with scope limited to the 
   spawned expression.  */

static tree
copy_decl_for_cilk (tree decl, copy_body_data *id)
{
  switch (TREE_CODE (decl))
    {
    case VAR_DECL:
      return copy_decl_no_change (decl, id);

    case LABEL_DECL:
      error_at (EXPR_LOCATION (decl), "invalid use of label %q+D in "
		"%<_Cilk_spawn%>", 
		decl);
      return error_mark_node;

    case RESULT_DECL:
    case PARM_DECL:
      /* RESULT_DECL and PARM_DECL has already been entered into the map.  */
    default:
      gcc_unreachable ();
      return error_mark_node;
    }
}

/* Alter a tree STMT from OUTER_FN to form the body of INNER_FN.  */

void
cilk_outline (tree inner_fn, tree *stmt_p, void *w)
{
  struct wrapper_data *wd = (struct wrapper_data *) w;
  const tree outer_fn = wd->context;
  const bool nested = (wd->type == CILK_BLOCK_FOR);
  copy_body_data id;
  bool throws;
  auto_vec<struct cilk_decls> vd;
  unsigned int j;
  struct cilk_decls * c;

  DECL_STATIC_CHAIN (outer_fn) = 1;

  memset (&id, 0, sizeof (id));
  /* Copy from the function containing the spawn...  */
  id.src_fn = outer_fn;

  /* ...to the wrapper.  */
  id.dst_fn = inner_fn; 
  id.src_cfun = DECL_STRUCT_FUNCTION (outer_fn);

  /* There shall be no RETURN in spawn helper.  */
  id.retvar = 0; 
  id.decl_map = wd->decl_map;
  id.copy_decl = nested ? copy_decl_no_change : copy_decl_for_cilk;
  id.block = DECL_INITIAL (inner_fn);
  id.transform_lang_insert_block = NULL;

  id.transform_new_cfg = true;
  id.transform_call_graph_edges = CB_CGE_MOVE;
  id.remap_var_for_cilk = true;
  id.regimplify = true; /* unused? */

  insert_decl_map (&id, wd->block, DECL_INITIAL (inner_fn));

  wd->decl_map->traverse<auto_vec<struct cilk_decls> *, fill_decls_vec> (&vd);
  vd.qsort (compare_decls);
  /* We don't want the private variables any more.  */
  FOR_EACH_VEC_ELT (vd, j, c)
   if (*(c->val) == error_mark_node)
     *(c->val) = nested ? copy_decl_no_change (c->key, &id)
			: copy_decl_for_cilk (c->key, &id);

  walk_tree (stmt_p, copy_tree_body_r, (void *) &id, NULL);

  /* See if this function can throw or calls something that should
     not be spawned.  The exception part is only necessary if
     flag_exceptions && !flag_non_call_exceptions.  */
  throws = false ;
  (void) walk_tree_without_duplicates (stmt_p, check_outlined_calls, &throws);
}

/* Generate the body of a wrapper function that assigns the
   result of the expression RHS into RECEIVER.  RECEIVER must
   be NULL if this is not a spawn -- the wrapper will return
   a value.  If this is a spawn, the wrapper will return void.  */

static tree
create_cilk_wrapper_body (tree stmt, struct wrapper_data *wd)
{
  const tree outer = current_function_decl;
  tree fndecl;
  tree p;

   /* Build the type of the wrapper and its argument list from the
     variables that it requires.  */
  build_wrapper_type (wd);

  /* Emit a function that takes WRAPPER_PARMS incoming and applies ARGS 
     (modified) to the wrapped function.  Return the wrapper and modified ARGS 
     to the caller to generate a function call.  */
  fndecl = create_cilk_helper_decl (wd);
  push_struct_function (fndecl);
  if (wd->nested && (wd->type == CILK_BLOCK_FOR))
    {
      gcc_assert (TREE_VALUE (wd->arglist) == NULL_TREE);
      TREE_VALUE (wd->arglist) = build2 (FDESC_EXPR, ptr_type_node,
					 fndecl, integer_one_node);
    }
  DECL_ARGUMENTS (fndecl) = wd->parms;

  for (p = wd->parms; p; p = TREE_CHAIN (p))
    DECL_CONTEXT (p) = fndecl;

  gcc_assert (!DECL_SAVED_TREE (fndecl));
  cilk_install_body_with_frame_cleanup (fndecl, stmt, (void *) wd);
  gcc_assert (DECL_SAVED_TREE (fndecl));

  pop_cfun_to (outer);

  /* Recognize the new function.  */
  call_graph_add_fn (fndecl);
  return fndecl;
}

/* Initializes the wrapper data structure.  */

static void
init_wd (struct wrapper_data *wd, enum cilk_block_type type)
{
  wd->type = type;
  wd->fntype = NULL_TREE;
  wd->context = current_function_decl;
  wd->decl_map = new hash_map<tree, tree>;
  /* _Cilk_for bodies are always nested.  Others start off as 
     normal functions.  */
  wd->nested = (type == CILK_BLOCK_FOR);
  wd->arglist = NULL_TREE;
  wd->argtypes = NULL_TREE;
  wd->block = NULL_TREE;
}

/* Clears the wrapper data structure.  */

static void
free_wd (struct wrapper_data *wd)
{
  delete wd->decl_map;
  wd->nested = false;
  wd->arglist = NULL_TREE;
  wd->argtypes = NULL_TREE;
  wd->parms = NULL_TREE;
}


 /* Given a variable in an expression to be extracted into
   a helper function, declare the helper function parameter
   to receive it.

   On entry the value of the (key, value) pair may be

   (*, error_mark_node) -- Variable is private to helper function,
   do nothing.

   (var, var) -- Reference to outer scope (function or global scope).

   (var, integer 0) -- Capture by value, save newly-declared PARM_DECL
   for value in value slot.

   (var, integer 1) -- Capture by reference, declare pointer to type
   as new PARM_DECL and store (spawn_stmt (indirect_ref (parm)).
   
   (var, ???) -- Pure output argument, handled similarly to above.
*/

bool
declare_one_free_variable (tree var0, tree *map0)
{
  const_tree var = var0;
  tree map = *map0;
  tree var_type = TREE_TYPE (var), arg_type;
  bool by_reference;
  tree parm;

  gcc_assert (DECL_P (var));

  /* Ignore truly local variables.  */
  if (map == error_mark_node)
    return true;
  /* Ignore references to the parent function.  */
  if (map == var)
    return true;

  gcc_assert (TREE_CODE (map) == INTEGER_CST);

  /* A value is passed by reference if:

     1. It is addressable, so that a copy may not be made.
     2. It is modified in the spawned statement.
     In the future this function may want to arrange
     a warning if the spawned statement is a loop body
     because an output argument would indicate a race.
     Note: Earlier passes must have marked the variable addressable.
     3. It is expensive to copy.  */
  by_reference =
    (TREE_ADDRESSABLE (var_type)
     /* Arrays must be passed by reference.  This is required for C
	semantics -- arrays are not first class objects.  Other
	aggregate types can and should be passed by reference if
	they are not passed to the spawned function.  We aren't yet
	distinguishing safe uses in argument calculation from unsafe
	uses as outgoing function arguments, so we make a copy to
	stabilize the value.  */
     || TREE_CODE (var_type) == ARRAY_TYPE
     || (tree) map == integer_one_node);

  if (by_reference)
    var_type = build_qualified_type (build_pointer_type (var_type),
				     TYPE_QUAL_RESTRICT);
  gcc_assert (!TREE_ADDRESSABLE (var_type));

  /* Maybe promote to int.  */
  if (INTEGRAL_TYPE_P (var_type) && COMPLETE_TYPE_P (var_type)
      && tree_int_cst_lt (TYPE_SIZE (var_type), TYPE_SIZE (integer_type_node)))
    arg_type = integer_type_node;
  else
    arg_type = var_type;

  parm = build_decl (UNKNOWN_LOCATION, PARM_DECL, NULL_TREE, var_type);
  DECL_ARG_TYPE (parm) = arg_type;
  DECL_ARTIFICIAL (parm) = 0;
  TREE_READONLY (parm) = 1;
  
  if (by_reference)
    {
      parm = build1 (INDIRECT_REF, TREE_TYPE (var_type), parm);
      parm = build1 (PAREN_EXPR, void_type_node, parm);
    }
  *map0 = parm;
  return true;
}
 
/* Returns a wrapper function for a _Cilk_spawn.  */

static tree
create_cilk_wrapper (tree exp, tree *args_out)
{
  struct wrapper_data wd;
  tree fndecl;
  unsigned int j;
  struct cilk_decls * c;
  auto_vec<struct cilk_decls> vd;

  init_wd (&wd, CILK_BLOCK_SPAWN);

  if (TREE_CODE (exp) == CONVERT_EXPR)
    exp = TREE_OPERAND (exp, 0);
  
  /* Special handling for top level INIT_EXPR.  Usually INIT_EXPR means the 
     variable is defined in the spawned expression and can be private to the 
     spawn helper.  A top level INIT_EXPR defines a variable to be initialized 
     by spawn and the variable must remain in the outer function.  */
  if (TREE_CODE (exp) == INIT_EXPR)
    {
      extract_free_variables (TREE_OPERAND (exp, 0), &wd, ADD_WRITE);
      extract_free_variables (TREE_OPERAND (exp, 1), &wd, ADD_READ);
      /* TREE_TYPE should be void.  Be defensive.  */
      if (TREE_TYPE (exp) != void_type_node)
	extract_free_variables (TREE_TYPE (exp), &wd, ADD_READ);
    }
  else
    extract_free_variables (exp, &wd, ADD_READ);
  wd.decl_map->traverse<auto_vec<struct cilk_decls> *, fill_decls_vec> (&vd);
  vd.qsort (compare_decls);
  FOR_EACH_VEC_ELT (vd, j, c)
   declare_one_free_variable (c->key, c->val);

  wd.block = TREE_BLOCK (exp);
  if (!wd.block)
    wd.block = DECL_INITIAL (current_function_decl);

  /* Now fvars maps the old variable to incoming variable.  Update
     the expression and arguments to refer to the new names.  */
  fndecl = create_cilk_wrapper_body (exp, &wd);
  *args_out = wd.arglist;
  
  free_wd (&wd);

  return fndecl;
}

/* Gimplify all the parameters for the Spawned function.  *EXPR_P can be a
   CALL_EXPR, INIT_EXPR, MODIFY_EXPR or TARGET_EXPR.  *PRE_P and *POST_P are
   gimple sequences from the caller of gimplify_cilk_spawn.  */

void
cilk_gimplify_call_params_in_spawned_fn (tree *expr_p, gimple_seq *pre_p,
					 gimple_seq *post_p)
{
  int ii = 0;
  tree *fix_parm_expr = expr_p;

  /* Remove CLEANUP_POINT_EXPR and EXPR_STMT from *spawn_p.  */
  while (TREE_CODE (*fix_parm_expr) == CLEANUP_POINT_EXPR
	 || TREE_CODE (*fix_parm_expr) == EXPR_STMT)
    *fix_parm_expr = TREE_OPERAND (*fix_parm_expr, 0);

  if ((TREE_CODE (*expr_p) == INIT_EXPR)
      || (TREE_CODE (*expr_p) == TARGET_EXPR)
      || (TREE_CODE (*expr_p) == MODIFY_EXPR))
    fix_parm_expr = &TREE_OPERAND (*expr_p, 1);

  if (TREE_CODE (*fix_parm_expr) == CALL_EXPR)
    for (ii = 0; ii < call_expr_nargs (*fix_parm_expr); ii++)
      gimplify_expr (&CALL_EXPR_ARG (*fix_parm_expr, ii), pre_p, post_p,
		     is_gimple_reg, fb_rvalue);
}


/* Transform *SPAWN_P, a spawned CALL_EXPR, to gimple.  *SPAWN_P can be a
   CALL_EXPR, INIT_EXPR or MODIFY_EXPR.  Returns GS_OK if everything is fine,
   and GS_UNHANDLED, otherwise.  */

int
gimplify_cilk_spawn (tree *spawn_p)
{
  tree expr = *spawn_p;
  tree function, call1, call2, new_args;
  tree ii_args = NULL_TREE;
  int total_args = 0, ii = 0;
  tree *arg_array;
  tree setjmp_cond_expr = NULL_TREE;
  tree setjmp_expr, spawn_expr, setjmp_value = NULL_TREE;

  cfun->calls_cilk_spawn = 1;
  cfun->is_cilk_function = 1;
  new_args = NULL;
  function = create_cilk_wrapper (expr, &new_args);

  /* This should give the number of parameters.  */
  total_args = list_length (new_args);
  if (total_args)
    arg_array = XNEWVEC (tree, total_args);
  else
    arg_array = NULL;

  ii_args = new_args;
  for (ii = 0; ii < total_args; ii++)
    {
      arg_array[ii] = TREE_VALUE (ii_args);
      ii_args = TREE_CHAIN (ii_args);
    }
  
  TREE_USED (function) = 1;
  rest_of_decl_compilation (function, 0, 0);

  call1 = cilk_call_setjmp (cfun->cilk_frame_decl);

  if (arg_array == NULL || *arg_array == NULL_TREE)
    call2 = build_call_expr (function, 0);
  else 
    call2 = build_call_expr_loc_array (EXPR_LOCATION (*spawn_p), function, 
					 total_args, arg_array);
  *spawn_p = alloc_stmt_list ();
  tree f_ptr_type = build_pointer_type (TREE_TYPE (cfun->cilk_frame_decl));
  tree frame_ptr = build1 (ADDR_EXPR, f_ptr_type, cfun->cilk_frame_decl);
  tree save_fp = build_call_expr (cilk_save_fp_fndecl, 1, frame_ptr);
  append_to_statement_list (save_fp, spawn_p);		  
  setjmp_value = create_tmp_var (TREE_TYPE (call1));
  setjmp_expr = fold_build2 (MODIFY_EXPR, void_type_node, setjmp_value, call1);

  append_to_statement_list_force (setjmp_expr, spawn_p);
  
  setjmp_cond_expr = fold_build2 (EQ_EXPR, TREE_TYPE (call1), setjmp_value,
				  build_int_cst (TREE_TYPE (call1), 0));
  spawn_expr = fold_build3 (COND_EXPR, void_type_node, setjmp_cond_expr,
			    call2, build_empty_stmt (EXPR_LOCATION (call1)));
  append_to_statement_list (spawn_expr, spawn_p);

  return GS_OK;
}

/* Make the frames necessary for a spawn call.  */

tree
make_cilk_frame (tree fn)
{
  struct function *f = DECL_STRUCT_FUNCTION (fn);
  tree decl;

  if (f->cilk_frame_decl)
    return f->cilk_frame_decl;

  decl = build_decl (EXPR_LOCATION (fn), VAR_DECL, NULL_TREE, 
		     cilk_frame_type_decl);
  DECL_CONTEXT (decl) = fn;
  DECL_SEEN_IN_BIND_EXPR_P (decl) = 1;
  f->cilk_frame_decl = decl;
  return decl;
}

/* Returns a STATEMENT_LIST with all the pedigree operations required for
   install body with frame cleanup functions.  FRAME_PTR is the pointer to
   __cilkrts_stack_frame created by make_cilk_frame.  */

tree
cilk_install_body_pedigree_operations (tree frame_ptr)
{
  tree body_list = alloc_stmt_list ();
  tree enter_frame = build_call_expr (cilk_enter_fast_fndecl, 1, frame_ptr); 
  append_to_statement_list (enter_frame, &body_list);
  
  tree parent = cilk_arrow (frame_ptr, CILK_TI_FRAME_PARENT, 0);
  tree worker = cilk_arrow (frame_ptr, CILK_TI_FRAME_WORKER, 0);

  tree pedigree = cilk_arrow (frame_ptr, CILK_TI_FRAME_PEDIGREE, 0);
  tree pedigree_rank = cilk_dot (pedigree, CILK_TI_PEDIGREE_RANK, 0);
  tree parent_pedigree = cilk_dot (pedigree, CILK_TI_PEDIGREE_PARENT, 0);
  tree pedigree_parent = cilk_arrow (parent, CILK_TI_FRAME_PEDIGREE, 0);
  tree pedigree_parent_rank = cilk_dot (pedigree_parent, 
					CILK_TI_PEDIGREE_RANK, 0);
  tree pedigree_parent_parent = cilk_dot (pedigree_parent, 
				     CILK_TI_PEDIGREE_PARENT, 0);
  tree worker_pedigree = cilk_arrow (worker, CILK_TI_WORKER_PEDIGREE, 1);
  tree w_pedigree_rank = cilk_dot (worker_pedigree, CILK_TI_PEDIGREE_RANK, 0);
  tree w_pedigree_parent = cilk_dot (worker_pedigree, 
				     CILK_TI_PEDIGREE_PARENT, 0);

  /* sf.pedigree.rank = worker->pedigree.rank.  */
  tree exp1 = build2 (MODIFY_EXPR, void_type_node, pedigree_rank,
		     w_pedigree_rank);
  append_to_statement_list (exp1, &body_list);

  /* sf.pedigree.parent = worker->pedigree.parent.  */
  exp1 = build2 (MODIFY_EXPR, void_type_node, parent_pedigree,
		 w_pedigree_parent);
  append_to_statement_list (exp1, &body_list);

  /* sf.call_parent->pedigree.rank = worker->pedigree.rank.  */
  exp1 = build2 (MODIFY_EXPR, void_type_node, pedigree_parent_rank,
		 w_pedigree_rank);
  append_to_statement_list (exp1, &body_list);

  /* sf.call_parent->pedigree.parent = worker->pedigree.parent.  */
  exp1 = build2 (MODIFY_EXPR, void_type_node, pedigree_parent_parent,
		 w_pedigree_parent);
  append_to_statement_list (exp1, &body_list);

  /* sf->worker.pedigree.rank = 0.  */
  exp1 = build2 (MODIFY_EXPR, void_type_node, w_pedigree_rank, 
		 build_zero_cst (uint64_type_node));
  append_to_statement_list (exp1, &body_list);

  /* sf->pedigree.parent = &sf->pedigree.  */
  exp1 = build2 (MODIFY_EXPR, void_type_node, w_pedigree_parent,
		 build1 (ADDR_EXPR,
			 build_pointer_type (cilk_pedigree_type_decl),
			 pedigree));
  append_to_statement_list (exp1, &body_list);
  return body_list;
}

/* Add a new variable, VAR to a variable list in WD->DECL_MAP.  HOW indicates
   whether the variable is previously defined, currently defined, or a variable 
   that is being written to.  */

static void
add_variable (struct wrapper_data *wd, tree var, enum add_variable_type how)
{
  tree *valp = wd->decl_map->get (var);
  if (valp)
    {
      tree val = (tree) *valp;
      /* If the variable is local, do nothing.  */
      if (val == error_mark_node)
	return;
      /* If the variable was entered with itself as value,
	 meaning it belongs to an outer scope, do not alter
	 the value.  */
      if (val == var) 
	return;
      /* A statement expression may cause a variable to be
	 bound twice, once in BIND_EXPR and again in a
	 DECL_EXPR.  That case caused a return in the 
	 test above.  Any other duplicate definition is
	 an error.  */
      gcc_assert (how != ADD_BIND);
      if (how != ADD_WRITE)
	return;
      /* This variable might have been entered as read but is now written.  */
      *valp = var;
      wd->nested = true;
      return;
    }
  else
    {
      tree val = NULL_TREE;

      /* Nested function rewriting silently discards hard register
	 assignments for function scope variables, and they wouldn't
	 work anyway.  Warn here.  This misses one case: if the
	 register variable is used as the loop bound or increment it
	 has already been added to the map.  */
      if ((how != ADD_BIND) && VAR_P (var)
	  && !DECL_EXTERNAL (var) && DECL_HARD_REGISTER (var))
	warning (0, "register assignment ignored for %qD used in Cilk block",
		 var);

      switch (how)
	{
	  /* ADD_BIND means always make a fresh new variable.  */
	case ADD_BIND:
	  val = error_mark_node;
	  break;
	  /* ADD_READ means
	     1. For cilk_for, refer to the outer scope definition as-is
	     2. For a spawned block, take a scalar in an rgument
	     and otherwise refer to the outer scope definition as-is.
	     3. For a spawned call, take a scalar in an argument.  */
	case ADD_READ:
	  switch (wd->type)
	    {
	    case CILK_BLOCK_FOR:
	      val = var;
	      break;
	    case CILK_BLOCK_SPAWN:
	      if (TREE_ADDRESSABLE (var))
		{
		  val = var;
		  wd->nested = true;
		  break;
		}
	      val = integer_zero_node;
	      break;
	    }
	  break;
	case ADD_WRITE:
	  switch (wd->type)
	    {
	    case CILK_BLOCK_FOR:
	      val = var;
	      wd->nested = true;
	      break;
	    case CILK_BLOCK_SPAWN:
	      if (TREE_ADDRESSABLE (var))
		val = integer_one_node;
	      else
		{
		  val = var;
		  wd->nested = true;
		}
	      break;
	    }
	}
      wd->decl_map->put (var, val);
    }
}

/* Find the variables referenced in an expression T.  This does not avoid 
   duplicates because a variable may be read in one context and written in 
   another.  HOW describes the context in which the reference is seen.  If 
   NESTED is true a nested function is being generated and variables in the 
   original context should not be remapped.  */

static void
extract_free_variables (tree t, struct wrapper_data *wd,
			enum add_variable_type how)
{  
  if (t == NULL_TREE)
    return;

  enum tree_code code = TREE_CODE (t);
  bool is_expr = IS_EXPR_CODE_CLASS (TREE_CODE_CLASS (code));

  if (is_expr)
    extract_free_variables (TREE_TYPE (t), wd, ADD_READ);

  switch (code)
    {
    case ERROR_MARK:
    case IDENTIFIER_NODE:
    case VOID_CST:
    case INTEGER_CST:
    case REAL_CST:
    case FIXED_CST:
    case STRING_CST:
    case BLOCK:
    case PLACEHOLDER_EXPR:
    case FIELD_DECL:
    case VOID_TYPE:
    case REAL_TYPE:
      /* These do not contain variable references.  */
      return;

    case SSA_NAME:
      /* Currently we don't see SSA_NAME.  */
      extract_free_variables (SSA_NAME_VAR (t), wd, how);
      return;

    case LABEL_DECL:
      /* This might be a reference to a label outside the Cilk block,
	 which is an error, or a reference to a label in the Cilk block
	 that we haven't seen yet.  We can't tell.  Ignore it.  An
	 invalid use will cause an error later in copy_decl_for_cilk.  */
      return;

    case RESULT_DECL:
      if (wd->type != CILK_BLOCK_SPAWN)
	TREE_ADDRESSABLE (t) = 1;
    case VAR_DECL:
    case PARM_DECL:
      if (!is_global_var (t))
	add_variable (wd, t, how);
      return;

    case NON_LVALUE_EXPR:
    case CONVERT_EXPR:
    case NOP_EXPR:
      extract_free_variables (TREE_OPERAND (t, 0), wd, ADD_READ);
      return;

    case VEC_INIT_EXPR:
    case INIT_EXPR:
      extract_free_variables (TREE_OPERAND (t, 0), wd, ADD_BIND);
      extract_free_variables (TREE_OPERAND (t, 1), wd, ADD_READ);
      return;

    case MODIFY_EXPR:
    case PREDECREMENT_EXPR:
    case PREINCREMENT_EXPR:
    case POSTDECREMENT_EXPR:
    case POSTINCREMENT_EXPR:
      /* These write their result.  */
      extract_free_variables (TREE_OPERAND (t, 0), wd, ADD_WRITE);
      extract_free_variables (TREE_OPERAND (t, 1), wd, ADD_READ);
      return;

    case ADDR_EXPR:
      /* This might modify its argument, and the value needs to be
	 passed by reference in any case to preserve identity and
	 type if is a promoting type.  In the case of a nested loop
	 just notice that we touch the variable.  It will already
	 be addressable, and marking it modified will cause a spurious
	 warning about writing the control variable.  */
      if (wd->type != CILK_BLOCK_SPAWN)
	extract_free_variables (TREE_OPERAND (t, 0), wd, ADD_READ);
      else 
	extract_free_variables (TREE_OPERAND (t, 0), wd, ADD_WRITE);
      return;

    case ARRAY_REF:
      /* Treating ARRAY_REF and BIT_FIELD_REF identically may
	 mark the array as written but the end result is correct
	 because the array is passed by pointer anyway.  */
    case BIT_FIELD_REF:
      /* Propagate the access type to the object part of which
	 is being accessed here.  As for ADDR_EXPR, don't do this
	 in a nested loop, unless the access is to a fixed index.  */
      if (wd->type != CILK_BLOCK_FOR || TREE_CONSTANT (TREE_OPERAND (t, 1)))
	extract_free_variables (TREE_OPERAND (t, 0), wd, how);
      else
	extract_free_variables (TREE_OPERAND (t, 0), wd, ADD_READ);
      extract_free_variables (TREE_OPERAND (t, 1), wd, ADD_READ);
      extract_free_variables (TREE_OPERAND (t, 2), wd, ADD_READ);
      return;

    case TREE_LIST:
      extract_free_variables (TREE_PURPOSE (t), wd, ADD_READ);
      extract_free_variables (TREE_VALUE (t), wd, ADD_READ);
      extract_free_variables (TREE_CHAIN (t), wd, ADD_READ);
      return;

    case TREE_VEC:
      {
	int len = TREE_VEC_LENGTH (t);
	int i;
	for (i = 0; i < len; i++)
	  extract_free_variables (TREE_VEC_ELT (t, i), wd, ADD_READ);
	return;
      }

    case VECTOR_CST:
      {
	unsigned ii = 0;
	for (ii = 0; ii < VECTOR_CST_NELTS (t); ii++)
	  extract_free_variables (VECTOR_CST_ELT (t, ii), wd, ADD_READ); 
	break;
      }

    case COMPLEX_CST:
      extract_free_variables (TREE_REALPART (t), wd, ADD_READ);
      extract_free_variables (TREE_IMAGPART (t), wd, ADD_READ);
      return;

    case BIND_EXPR:
      {
	tree decl;
	for (decl = BIND_EXPR_VARS (t); decl; decl = TREE_CHAIN (decl))
	  {
	    add_variable (wd, decl, ADD_BIND);
	    /* A self-referential initialization is no problem because
	       we already entered the variable into the map as local.  */
	    extract_free_variables (DECL_INITIAL (decl), wd, ADD_READ);
	    extract_free_variables (DECL_SIZE (decl), wd, ADD_READ);
	    extract_free_variables (DECL_SIZE_UNIT (decl), wd, ADD_READ);
	  }
	extract_free_variables (BIND_EXPR_BODY (t), wd, ADD_READ);
	return;
      }

    case STATEMENT_LIST:
      {
	tree_stmt_iterator i;
	for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
	  extract_free_variables (*tsi_stmt_ptr (i), wd, ADD_READ);
	return;
      }

    case TARGET_EXPR:
      {
	extract_free_variables (TREE_OPERAND (t, 0), wd, ADD_BIND);
	extract_free_variables (TREE_OPERAND (t, 1), wd, ADD_READ);
	extract_free_variables (TREE_OPERAND (t, 2), wd, ADD_READ);
	if (TREE_OPERAND (t, 3) != TREE_OPERAND (t, 1))
	  extract_free_variables (TREE_OPERAND (t, 3), wd, ADD_READ);
	return;
      }

    case RETURN_EXPR:
      if (TREE_NO_WARNING (t))
	{
	  gcc_assert (errorcount);
	  return;
	}
      return;

    case DECL_EXPR:
      if (TREE_CODE (DECL_EXPR_DECL (t)) != TYPE_DECL)
	extract_free_variables (DECL_EXPR_DECL (t), wd, ADD_BIND);
      return;

    case INTEGER_TYPE:
    case ENUMERAL_TYPE:
    case BOOLEAN_TYPE:
      extract_free_variables (TYPE_MIN_VALUE (t), wd, ADD_READ);
      extract_free_variables (TYPE_MAX_VALUE (t), wd, ADD_READ);
      return;

    case POINTER_TYPE:
      extract_free_variables (TREE_TYPE (t), wd, ADD_READ);
      break;

    case ARRAY_TYPE:
      extract_free_variables (TREE_TYPE (t), wd, ADD_READ);
      extract_free_variables (TYPE_DOMAIN (t), wd, ADD_READ);
      return;

    case RECORD_TYPE:
      extract_free_variables (TYPE_FIELDS (t), wd, ADD_READ);
      return;
    
    case METHOD_TYPE:
      extract_free_variables (TYPE_ARG_TYPES (t), wd, ADD_READ);
      extract_free_variables (TYPE_METHOD_BASETYPE (t), wd, ADD_READ);
      return;

    case AGGR_INIT_EXPR:
    case CALL_EXPR:
      {
	int len = 0;
	int ii = 0;
	if (TREE_CODE (TREE_OPERAND (t, 0)) == INTEGER_CST)
	  {
	    len = TREE_INT_CST_LOW (TREE_OPERAND (t, 0));

	    for (ii = 0; ii < len; ii++)
	      extract_free_variables (TREE_OPERAND (t, ii), wd, ADD_READ);
	    extract_free_variables (TREE_TYPE (t), wd, ADD_READ);
	  }
	break;
      }

    case CONSTRUCTOR:
      {
	unsigned HOST_WIDE_INT idx = 0;
	constructor_elt *ce;
	for (idx = 0; vec_safe_iterate (CONSTRUCTOR_ELTS (t), idx, &ce); idx++)
	  extract_free_variables (ce->value, wd, ADD_READ);
	break;
      }

    default:
      if (is_expr)
	{
	  int i, len;

	  /* Walk over all the sub-trees of this operand.  */
	  len = TREE_CODE_LENGTH (code);

	  /* Go through the subtrees.  We need to do this in forward order so
	     that the scope of a FOR_EXPR is handled properly.  */
	  for (i = 0; i < len; ++i)
	    extract_free_variables (TREE_OPERAND (t, i), wd, ADD_READ);
	}
    }
}

/* Add appropriate frames needed for a Cilk spawned function call, FNDECL. 
   Returns the __cilkrts_stack_frame * variable.  */

tree
insert_cilk_frame (tree fndecl)
{
  tree addr, body, enter, out, orig_body;
  location_t loc = EXPR_LOCATION (fndecl);

  if (!cfun || cfun->decl != fndecl)
    push_cfun (DECL_STRUCT_FUNCTION (fndecl)); 

  tree decl = cfun->cilk_frame_decl;
  if (!decl)
    {
      tree *saved_tree = &DECL_SAVED_TREE (fndecl);
      decl = make_cilk_frame (fndecl);
      add_local_decl (cfun, decl);

      addr = build1 (ADDR_EXPR, cilk_frame_ptr_type_decl, decl);
      enter = build_call_expr (cilk_enter_fndecl, 1, addr);
      out = create_cilk_function_exit (cfun->cilk_frame_decl, false, true);

      /* The new body will be:
	 __cilkrts_enter_frame_1 (&sf);
	 try {
	    orig_body;
	 } 
	 finally {
	     __cilkrts_pop_frame (&sf);
	     __cilkrts_leave_frame (&sf);
         }  */

      body = alloc_stmt_list ();
      orig_body = *saved_tree;

      if (TREE_CODE (orig_body) == BIND_EXPR)
	orig_body = BIND_EXPR_BODY (orig_body);
 
      append_to_statement_list (enter, &body);
      append_to_statement_list (build_stmt (loc, TRY_FINALLY_EXPR, orig_body, 
					    out), &body);
      if (TREE_CODE (*saved_tree) == BIND_EXPR)
	BIND_EXPR_BODY (*saved_tree) = body;
      else
	*saved_tree = body;
    }
  return decl;
}

/* Wraps CALL, a CALL_EXPR, into a CILK_SPAWN_STMT tree and returns it.  */

tree
build_cilk_spawn (location_t loc, tree call)
{
  if (!cilk_set_spawn_marker (loc, call))
    return error_mark_node;
  tree spawn_stmt = build1 (CILK_SPAWN_STMT, TREE_TYPE (call), call);
  TREE_SIDE_EFFECTS (spawn_stmt) = 1;
  return spawn_stmt;
}

/* Returns a tree of type CILK_SYNC_STMT.  */

tree
build_cilk_sync (void)
{
  tree sync = build0 (CILK_SYNC_STMT, void_type_node);
  TREE_SIDE_EFFECTS (sync) = 1;
  return sync;
}

/* Helper for contains_cilk_spawn_stmt, callback for walk_tree.  Return
   non-null tree if TP contains CILK_SPAWN_STMT.  */

static tree
contains_cilk_spawn_stmt_walker (tree *tp, int *, void *)
{
  if (TREE_CODE (*tp) == CILK_SPAWN_STMT)
    return *tp;
  else
    return NULL_TREE;
}

/* Returns true if EXPR or any of its subtrees contain CILK_SPAWN_STMT
   node.  */

bool
contains_cilk_spawn_stmt (tree expr)
{
  return walk_tree (&expr, contains_cilk_spawn_stmt_walker, NULL, NULL)
	 != NULL_TREE;
}

/* Return a error location for EXPR if LOC is not set.  */

static location_t
get_error_location (tree expr, location_t loc)
{
  if (loc == UNKNOWN_LOCATION)
    {
      if (TREE_CODE (expr) == MODIFY_EXPR)
        expr = TREE_OPERAND (expr, 0);
      loc = EXPR_LOCATION (expr);
    }
  return loc;
}

/* Check that no array notation or spawn statement is in EXPR.
   If not true generate an error at LOC for ARRAY_GMSGID or
   SPAWN_MSGID.  */

bool
check_no_cilk (tree expr, const char *array_msgid, const char *spawn_msgid,
	      location_t loc)
{
  if (!flag_cilkplus)
    return false;
  if (contains_array_notation_expr (expr))
    {
      loc = get_error_location (expr, loc);
      error_at (loc, array_msgid);
      return true;
    }
  if (walk_tree (&expr, contains_cilk_spawn_stmt_walker, NULL, NULL))
    {
      loc = get_error_location (expr, loc);
      error_at (loc, spawn_msgid);
      return true;
    }
  return false;
}