aboutsummaryrefslogtreecommitdiffstats
path: root/gcc-4.9/gcc/ipa.c
blob: 5d2465c83887b62c0b919b16ea00f06f3923c8ff (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
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
/* Basic IPA optimizations and utilities.
   Copyright (C) 2003-2014 Free Software Foundation, Inc.

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 "tree.h"
#include "calls.h"
#include "stringpool.h"
#include "cgraph.h"
#include "toplev.h"
#include "tree-pass.h"
#include "pointer-set.h"
#include "gimple-expr.h"
#include "gimplify.h"
#include "flags.h"
#include "target.h"
#include "tree-iterator.h"
#include "l-ipo.h"
#include "ipa-utils.h"
#include "ipa-inline.h"
#include "tree-inline.h"
#include "profile.h"
#include "params.h"
#include "l-ipo.h"

/* Return true when NODE can not be local. Worker for cgraph_local_node_p.  */

static bool
cgraph_non_local_node_p_1 (struct cgraph_node *node, void *data ATTRIBUTE_UNUSED)
{
   /* FIXME: Aliases can be local, but i386 gets thunks wrong then.  */
   return !(cgraph_only_called_directly_or_aliased_p (node)
	    && !ipa_ref_has_aliases_p (&node->ref_list)
	    && node->definition
	    && !DECL_EXTERNAL (node->decl)
	    && !node->externally_visible
	    && !node->used_from_other_partition
	    && !node->in_other_partition);
}

/* Return true when function can be marked local.  */

static bool
cgraph_local_node_p (struct cgraph_node *node)
{
   struct cgraph_node *n = cgraph_function_or_thunk_node (node, NULL);

   /* FIXME: thunks can be considered local, but we need prevent i386
      from attempting to change calling convention of them.  */
   if (n->thunk.thunk_p)
     return false;
   return !cgraph_for_node_and_aliases (n,
					cgraph_non_local_node_p_1, NULL, true);
					
}

/* Return true when NODE has ADDR reference.  */

static bool
has_addr_references_p (struct cgraph_node *node,
		       void *data ATTRIBUTE_UNUSED)
{
  int i;
  struct ipa_ref *ref;

  for (i = 0; ipa_ref_list_referring_iterate (&node->ref_list,
					      i, ref); i++)
    if (ref->use == IPA_REF_ADDR)
      return true;
  return false;
}

/* Look for all functions inlined to NODE and update their inlined_to pointers
   to INLINED_TO.  */

static void
update_inlined_to_pointer (struct cgraph_node *node, struct cgraph_node *inlined_to)
{
  struct cgraph_edge *e;
  for (e = node->callees; e; e = e->next_callee)
    if (e->callee->global.inlined_to)
      {
        e->callee->global.inlined_to = inlined_to;
	update_inlined_to_pointer (e->callee, inlined_to);
      }
}

/* Add symtab NODE to queue starting at FIRST.

   The queue is linked via AUX pointers and terminated by pointer to 1.
   We enqueue nodes at two occasions: when we find them reachable or when we find
   their bodies needed for further clonning.  In the second case we mark them
   by pointer to 2 after processing so they are re-queue when they become
   reachable.  */

static void
enqueue_node (symtab_node *node, symtab_node **first,
	      struct pointer_set_t *reachable)
{
  /* Node is still in queue; do nothing.  */
  if (node->aux && node->aux != (void *) 2)
    return;
  /* Node was already processed as unreachable, re-enqueue
     only if it became reachable now.  */
  if (node->aux == (void *)2 && !pointer_set_contains (reachable, node))
    return;
  node->aux = *first;
  *first = node;
}

/* Process references.  */

static void
process_references (struct ipa_ref_list *list,
		    symtab_node **first,
		    bool before_inlining_p,
		    struct pointer_set_t *reachable)
{
  int i;
  struct ipa_ref *ref;
  for (i = 0; ipa_ref_list_reference_iterate (list, i, ref); i++)
    {
      symtab_node *node = ref->referred;

      if (node->definition && !node->in_other_partition
	  && ((!(DECL_EXTERNAL (node->decl)
               || (is_a <cgraph_node> (node)
                   && cgraph_is_aux_decl_external (dyn_cast<cgraph_node> (node))))
              || node->alias)
	      || (((before_inlining_p
		    && (cgraph_state < CGRAPH_STATE_IPA_SSA
		        || !lookup_attribute ("always_inline",
					      DECL_ATTRIBUTES (node->decl)))))
		  /* We use variable constructors during late complation for
		     constant folding.  Keep references alive so partitioning
		     knows about potential references.  */
		  || (TREE_CODE (node->decl) == VAR_DECL
		      && flag_wpa
		      && ctor_for_folding (node->decl)
		         != error_mark_node))))
	pointer_set_insert (reachable, node);
      else if (L_IPO_COMP_MODE
               && cgraph_pre_profiling_inlining_done
               && is_a <varpool_node> (node)
               && ctor_for_folding (real_varpool_node (node->decl)->decl)
               != error_mark_node)
	pointer_set_insert (reachable, node);

      enqueue_node (node, first, reachable);
    }
}

/* EDGE is an polymorphic call.  If BEFORE_INLINING_P is set, mark
   all its potential targets as reachable to permit later inlining if
   devirtualization happens.  After inlining still keep their declarations
   around, so we can devirtualize to a direct call.

   Also try to make trivial devirutalization when no or only one target is
   possible.  */

static void
walk_polymorphic_call_targets (pointer_set_t *reachable_call_targets,
			       struct cgraph_edge *edge,
			       symtab_node **first,
			       pointer_set_t *reachable, bool before_inlining_p)
{
  unsigned int i;
  void *cache_token;
  bool final;
  vec <cgraph_node *>targets
    = possible_polymorphic_call_targets
	(edge, &final, &cache_token);

  if (!pointer_set_insert (reachable_call_targets,
			   cache_token))
    {
      for (i = 0; i < targets.length (); i++)
	{
	  struct cgraph_node *n = targets[i];

	  if (L_IPO_COMP_MODE && cgraph_pre_profiling_inlining_done)
	    n = cgraph_lipo_get_resolved_node (n->decl);

	  /* Do not bother to mark virtual methods in anonymous namespace;
	     either we will find use of virtual table defining it, or it is
	     unused.  */
	  if (TREE_CODE (TREE_TYPE (n->decl)) == METHOD_TYPE
	      && type_in_anonymous_namespace_p
		    (method_class_type (TREE_TYPE (n->decl))))
	    continue;

	  /* Prior inlining, keep alive bodies of possible targets for
	     devirtualization.  */
	   if (n->definition
	       && (before_inlining_p
		   && (cgraph_state < CGRAPH_STATE_IPA_SSA
		       || !lookup_attribute ("always_inline",
					     DECL_ATTRIBUTES (n->decl)))))
	     pointer_set_insert (reachable, n);

	  /* Even after inlining we want to keep the possible targets in the
	     boundary, so late passes can still produce direct call even if
	     the chance for inlining is lost.  */
	  enqueue_node (n, first, reachable);
	}
    }

  /* Very trivial devirtualization; when the type is
     final or anonymous (so we know all its derivation)
     and there is only one possible virtual call target,
     make the edge direct.  */
  if (final)
    {
      if (targets.length () <= 1)
	{
	  cgraph_node *target, *node = edge->caller;
	  if (targets.length () == 1)
	    target = targets[0];
	  else
	    target = cgraph_get_create_node
		       (builtin_decl_implicit (BUILT_IN_UNREACHABLE));

	  if (dump_file)
	    fprintf (dump_file,
		     "Devirtualizing call in %s/%i to %s/%i\n",
		     edge->caller->name (),
		     edge->caller->order,
		     target->name (), target->order);
	  edge = cgraph_make_edge_direct (edge, target);
	  if (inline_summary_vec)
	    inline_update_overall_summary (node);
	  else if (edge->call_stmt)
	    cgraph_redirect_edge_call_stmt_to_callee (edge);
	}
    }
}

/* Perform reachability analysis and reclaim all unreachable nodes.

   The algorithm is basically mark&sweep but with some extra refinements:

   - reachable extern inline functions needs special handling; the bodies needs
     to stay in memory until inlining in hope that they will be inlined.
     After inlining we release their bodies and turn them into unanalyzed
     nodes even when they are reachable.

     BEFORE_INLINING_P specify whether we are before or after inlining.

   - virtual functions are kept in callgraph even if they seem unreachable in
     hope calls to them will be devirtualized. 

     Again we remove them after inlining.  In late optimization some
     devirtualization may happen, but it is not important since we won't inline
     the call. In theory early opts and IPA should work out all important cases.

   - virtual clones needs bodies of their origins for later materialization;
     this means that we want to keep the body even if the origin is unreachable
     otherwise.  To avoid origin from sitting in the callgraph and being
     walked by IPA passes, we turn them into unanalyzed nodes with body
     defined.

     We maintain set of function declaration where body needs to stay in
     body_needed_for_clonning

     Inline clones represent special case: their declaration match the
     declaration of origin and cgraph_remove_node already knows how to
     reshape callgraph and preserve body when offline copy of function or
     inline clone is being removed.

   - C++ virtual tables keyed to other unit are represented as DECL_EXTERNAL
     variables with DECL_INITIAL set.  We finalize these and keep reachable
     ones around for constant folding purposes.  After inlining we however
     stop walking their references to let everything static referneced by them
     to be removed when it is otherwise unreachable.

   We maintain queue of both reachable symbols (i.e. defined symbols that needs
   to stay) and symbols that are in boundary (i.e. external symbols referenced
   by reachable symbols or origins of clones).  The queue is represented
   as linked list by AUX pointer terminated by 1.

   At the end we keep all reachable symbols. For symbols in boundary we always
   turn definition into a declaration, but we may keep function body around
   based on body_needed_for_clonning

   All symbols that enter the queue have AUX pointer non-zero and are in the
   boundary.  Pointer set REACHABLE is used to track reachable symbols.

   Every symbol can be visited twice - once as part of boundary and once
   as real reachable symbol. enqueue_node needs to decide whether the
   node needs to be re-queued for second processing.  For this purpose
   we set AUX pointer of processed symbols in the boundary to constant 2.  */

bool
symtab_remove_unreachable_nodes (bool before_inlining_p, FILE *file)
{
  symtab_node *first = (symtab_node *) (void *) 1;
  struct cgraph_node *node, *next;
  varpool_node *vnode, *vnext;
  bool changed = false;
  struct pointer_set_t *reachable = pointer_set_create ();
  struct pointer_set_t *body_needed_for_clonning = pointer_set_create ();
  struct pointer_set_t *reachable_call_targets = pointer_set_create ();

  /* In LIPO mode, do not remove functions until after global linking
     is performed. Otherwise functions needed for cross module inlining
     may get eliminated. Global linking will be done just before tree
     profiling.  */
  if (L_IPO_COMP_MODE
     && !cgraph_pre_profiling_inlining_done)
    return false;

  timevar_push (TV_IPA_UNREACHABLE);
#ifdef ENABLE_CHECKING
  verify_symtab ();
#endif
  if (optimize && flag_devirtualize)
    build_type_inheritance_graph ();
  if (file)
    fprintf (file, "\nReclaiming functions:");
#ifdef ENABLE_CHECKING
  FOR_EACH_FUNCTION (node)
    gcc_assert (!node->aux);
  FOR_EACH_VARIABLE (vnode)
    gcc_assert (!vnode->aux);
#endif
  /* Mark functions whose bodies are obviously needed.
     This is mostly when they can be referenced externally.  Inline clones
     are special since their declarations are shared with master clone and thus
     cgraph_can_remove_if_no_direct_calls_and_refs_p should not be called on them.  */
  FOR_EACH_FUNCTION (node)
    {
      node->used_as_abstract_origin = false;
      if (node->definition
	  && !node->global.inlined_to
	  && !node->in_other_partition
	  && !cgraph_can_remove_if_no_direct_calls_and_refs_p (node))
	{
	  gcc_assert (!node->global.inlined_to);
	  pointer_set_insert (reachable, node);
	  enqueue_node (node, &first, reachable);
	}
      else
	gcc_assert (!node->aux);
     }

  /* Mark variables that are obviously needed.  */
  FOR_EACH_DEFINED_VARIABLE (vnode)
    if (!varpool_can_remove_if_no_refs (vnode)
	&& !vnode->in_other_partition)
      {
	pointer_set_insert (reachable, vnode);
	enqueue_node (vnode, &first, reachable);
      }

  /* Perform reachability analysis.  */
  while (first != (symtab_node *) (void *) 1)
    {
      bool in_boundary_p = !pointer_set_contains (reachable, first);
      symtab_node *node = first;

      first = (symtab_node *)first->aux;

      /* If we are processing symbol in boundary, mark its AUX pointer for
	 possible later re-processing in enqueue_node.  */
      if (in_boundary_p)
	node->aux = (void *)2;
      else
	{
	  if (TREE_CODE (node->decl) == FUNCTION_DECL
	      && DECL_ABSTRACT_ORIGIN (node->decl))
	    {
	      struct cgraph_node *origin_node
	      = cgraph_get_node (DECL_ABSTRACT_ORIGIN (node->decl));
	      if (origin_node && !origin_node->used_as_abstract_origin)
		{
	          origin_node->used_as_abstract_origin = true;
		  gcc_assert (!origin_node->prev_sibling_clone);
		  gcc_assert (!origin_node->next_sibling_clone);
		  for (cgraph_node *n = origin_node->clones; n;
		       n = n->next_sibling_clone)
		    if (n->decl == DECL_ABSTRACT_ORIGIN (node->decl))
		      n->used_as_abstract_origin = true;
		}
	    }
	  /* If any symbol in a comdat group is reachable, force
	     all externally visible symbols in the same comdat
	     group to be reachable as well.  Comdat-local symbols
	     can be discarded if all uses were inlined.  */
	  if (node->same_comdat_group)
	    {
	      symtab_node *next;
	      for (next = node->same_comdat_group;
		   next != node;
		   next = next->same_comdat_group)
		if (!symtab_comdat_local_p (next)
		    && !pointer_set_insert (reachable, next))
		  enqueue_node (next, &first, reachable);
	    }
	  /* Mark references as reachable.  */
	  process_references (&node->ref_list, &first,
			      before_inlining_p, reachable);
	}

      if (cgraph_node *cnode = dyn_cast <cgraph_node> (node))
	{
	  /* Mark the callees reachable unless they are direct calls to extern
 	     inline functions we decided to not inline.  */
	  if (!in_boundary_p)
	    {
	      struct cgraph_edge *e;
	      /* Keep alive possible targets for devirtualization.  */
	      if (optimize && flag_devirtualize)
		{
		  struct cgraph_edge *next;
		  for (e = cnode->indirect_calls; e; e = next)
		    {
		      next = e->next_callee;
		      if (e->indirect_info->polymorphic)
			walk_polymorphic_call_targets (reachable_call_targets,
						       e, &first, reachable,
						       before_inlining_p);
		    }
		}
	      for (e = cnode->callees; e; e = e->next_callee)
		{
		  if (e->callee->definition
		      && !e->callee->in_other_partition
		      && (!e->inline_failed
			  || !(DECL_EXTERNAL (e->callee->decl)
			       || cgraph_is_aux_decl_external (e->callee))
			  || e->callee->alias
			  || before_inlining_p))
		    {
		      /* Be sure that we will not optimize out alias target
			 body.  */
		      if (DECL_EXTERNAL (e->callee->decl)
			  && e->callee->alias
			  && before_inlining_p)
			{
		          pointer_set_insert (reachable,
					      cgraph_function_node (e->callee));
			}
		      pointer_set_insert (reachable, e->callee);
		    }
		  enqueue_node (e->callee, &first, reachable);
		}

	      /* When inline clone exists, mark body to be preserved so when removing
		 offline copy of the function we don't kill it.  */
	      if (cnode->global.inlined_to)
	        pointer_set_insert (body_needed_for_clonning, cnode->decl);

	      /* For non-inline clones, force their origins to the boundary and ensure
		 that body is not removed.  */
	      while (cnode->clone_of)
		{
		  bool noninline = cnode->clone_of->decl != cnode->decl;
		  cnode = cnode->clone_of;
		  if (noninline)
		    {
		      pointer_set_insert (body_needed_for_clonning, cnode->decl);
		      enqueue_node (cnode, &first, reachable);
		    }
		}

	    }
	  /* If any reachable function has simd clones, mark them as
	     reachable as well.  */
	  if (cnode->simd_clones)
	    {
	      cgraph_node *next;
	      for (next = cnode->simd_clones;
		   next;
		   next = next->simdclone->next_clone)
		if (in_boundary_p
		    || !pointer_set_insert (reachable, next))
		  enqueue_node (next, &first, reachable);
	    }
	}
      /* When we see constructor of external variable, keep referred nodes in the
	boundary.  This will also hold initializers of the external vars NODE
	refers to.  */
      varpool_node *vnode = dyn_cast <varpool_node> (node);
      if (vnode
	  && DECL_EXTERNAL (node->decl)
	  && !vnode->alias
	  && in_boundary_p)
	{
	  struct ipa_ref *ref;
	  for (int i = 0; ipa_ref_list_reference_iterate (&node->ref_list, i, ref); i++)
	    enqueue_node (ref->referred, &first, reachable);
	}
    }

  /* Remove unreachable functions.   */
  for (node = cgraph_first_function (); node; node = next)
    {
      next = cgraph_next_function (node);

      /* If node is not needed at all, remove it.  */
      if (!node->aux)
	{
	  if (file)
	    fprintf (file, " %s/%i", node->name (), node->order);
	  cgraph_remove_node (node);
	  changed = true;
	}
      /* If node is unreachable, remove its body.  */
      else if (!pointer_set_contains (reachable, node))
        {
	  if (!pointer_set_contains (body_needed_for_clonning, node->decl))
	    cgraph_release_function_body (node);
	  else if (!node->clone_of)
	    gcc_assert (in_lto_p || DECL_RESULT (node->decl));
	  if (node->definition)
	    {
	      if (file)
		fprintf (file, " %s/%i", node->name (), node->order);
	      node->body_removed = true;
	      node->analyzed = false;
	      node->definition = false;
	      node->cpp_implicit_alias = false;
	      node->alias = false;
	      node->thunk.thunk_p = false;
	      node->weakref = false;
	      /* After early inlining we drop always_inline attributes on
		 bodies of functions that are still referenced (have their
		 address taken).  */
	      DECL_ATTRIBUTES (node->decl)
		= remove_attribute ("always_inline",
				    DECL_ATTRIBUTES (node->decl));
	      if (!node->in_other_partition)
		node->local.local = false;
#ifdef FIXME_LIPO
error " Check the following code "
#endif
              if (!cgraph_is_aux_decl_external (node)) {
	      cgraph_node_remove_callees (node);
	      symtab_remove_from_same_comdat_group (node);
	      ipa_remove_all_references (&node->ref_list);
              }
	      changed = true;
	    }
	}
      else
	gcc_assert (node->clone_of || !cgraph_function_with_gimple_body_p (node)
		    || in_lto_p || DECL_RESULT (node->decl));
    }

  /* Inline clones might be kept around so their materializing allows further
     cloning.  If the function the clone is inlined into is removed, we need
     to turn it into normal cone.  */
  FOR_EACH_FUNCTION (node)
    {
      if (node->global.inlined_to
	  && !node->callers)
	{
          /* Clean up dangling references from callees as well.
             TODO -- should be done recursively.  */
          if (L_IPO_COMP_MODE)
            {
	      struct cgraph_edge *e;
              for (e = node->callees; e; e = e->next_callee)
                {
                  struct cgraph_node *callee_node;

                  callee_node = e->callee;
                  if (callee_node->global.inlined_to)
                    callee_node->global.inlined_to = node;
                }
            }
	  gcc_assert (node->clones);
	  node->global.inlined_to = NULL;
	  update_inlined_to_pointer (node, node);
	}
      node->aux = NULL;
    }

  /* Remove unreachable variables.  */
  if (file)
    fprintf (file, "\n");

  if (file)
    fprintf (file, "Reclaiming variables:");
  for (vnode = varpool_first_variable (); vnode; vnode = vnext)
    {
      vnext = varpool_next_variable (vnode);
      if (!vnode->aux
	  /* For can_refer_decl_in_current_unit_p we want to track for
	     all external variables if they are defined in other partition
	     or not.  */
	  && (!flag_ltrans || !DECL_EXTERNAL (vnode->decl)))
	{
	  if (file)
	    fprintf (file, " %s/%i", vnode->name (), vnode->order);
	  varpool_remove_node (vnode);
	  changed = true;
	}
      else if (!pointer_set_contains (reachable, vnode))
        {
	  tree init;
	  if (vnode->definition)
	    {
	      if (file)
		fprintf (file, " %s", vnode->name ());
	      changed = true;
	    }
	  vnode->body_removed = true;
	  vnode->definition = false;
	  vnode->analyzed = false;
	  vnode->aux = NULL;

	  symtab_remove_from_same_comdat_group (vnode);

	  /* Keep body if it may be useful for constant folding.  */
	  if ((init = ctor_for_folding (vnode->decl)) == error_mark_node)
	    varpool_remove_initializer (vnode);
	  else
	    DECL_INITIAL (vnode->decl) = init;
	  ipa_remove_all_references (&vnode->ref_list);
	}
      else
	vnode->aux = NULL;
    }

  pointer_set_destroy (reachable);
  pointer_set_destroy (body_needed_for_clonning);
  pointer_set_destroy (reachable_call_targets);

  /* Now update address_taken flags and try to promote functions to be local.  */
  if (file)
    fprintf (file, "\nClearing address taken flags:");
  FOR_EACH_DEFINED_FUNCTION (node)
    if (node->address_taken
	&& !node->used_from_other_partition)
      {
	if (!cgraph_for_node_and_aliases (node, has_addr_references_p, NULL, true))
	  {
	    if (file)
	      fprintf (file, " %s", node->name ());
	    node->address_taken = false;
	    changed = true;
	    if (cgraph_local_node_p (node))
	      {
		node->local.local = true;
		if (file)
		  fprintf (file, " (local)");
	      }
	  }
      }
  if (file)
    fprintf (file, "\n");

#ifdef ENABLE_CHECKING
  verify_symtab ();
#endif

  /* If we removed something, perhaps profile could be improved.  */
  if (changed && optimize && inline_edge_summary_vec.exists ())
    FOR_EACH_DEFINED_FUNCTION (node)
      ipa_propagate_frequency (node);

  timevar_pop (TV_IPA_UNREACHABLE);
  return changed;
}

/* Discover variables that have no longer address taken or that are read only
   and update their flags.

   FIXME: This can not be done in between gimplify and omp_expand since
   readonly flag plays role on what is shared and what is not.  Currently we do
   this transformation as part of whole program visibility and re-do at
   ipa-reference pass (to take into account clonning), but it would
   make sense to do it before early optimizations.  */

void
ipa_discover_readonly_nonaddressable_vars (void)
{
  varpool_node *vnode;
  if (dump_file)
    fprintf (dump_file, "Clearing variable flags:");
  FOR_EACH_VARIABLE (vnode)
    if (vnode->definition && varpool_all_refs_explicit_p (vnode)
	&& (TREE_ADDRESSABLE (vnode->decl)
	    || !TREE_READONLY (vnode->decl)))
      {
	bool written = false;
	bool address_taken = false;
	int i;
        struct ipa_ref *ref;
        for (i = 0; ipa_ref_list_referring_iterate (&vnode->ref_list,
						   i, ref)
		    && (!written || !address_taken); i++)
	  switch (ref->use)
	    {
	    case IPA_REF_ADDR:
	      address_taken = true;
	      break;
	    case IPA_REF_LOAD:
	      break;
	    case IPA_REF_STORE:
	      written = true;
	      break;
	    }
	if (TREE_ADDRESSABLE (vnode->decl) && !address_taken)
	  {
	    if (dump_file)
	      fprintf (dump_file, " %s (addressable)", vnode->name ());
	    TREE_ADDRESSABLE (vnode->decl) = 0;
	  }
	if (!TREE_READONLY (vnode->decl) && !address_taken && !written
	    /* Making variable in explicit section readonly can cause section
	       type conflict. 
	       See e.g. gcc.c-torture/compile/pr23237.c */
	    && DECL_SECTION_NAME (vnode->decl) == NULL)
	  {
	    if (dump_file)
	      fprintf (dump_file, " %s (read-only)", vnode->name ());
	    TREE_READONLY (vnode->decl) = 1;
	  }
      }
  if (dump_file)
    fprintf (dump_file, "\n");
}

/* Return true when there is a reference to node and it is not vtable.  */
static bool
address_taken_from_non_vtable_p (symtab_node *node)
{
  int i;
  struct ipa_ref *ref;
  for (i = 0; ipa_ref_list_referring_iterate (&node->ref_list,
					     i, ref); i++)
    if (ref->use == IPA_REF_ADDR)
      {
	varpool_node *node;
	if (is_a <cgraph_node> (ref->referring))
	  return true;
	node = ipa_ref_referring_varpool_node (ref);
	if (!DECL_VIRTUAL_P (node->decl))
	  return true;
      }
  return false;
}

/* A helper for comdat_can_be_unshared_p.  */

static bool
comdat_can_be_unshared_p_1 (symtab_node *node)
{
  if (!node->externally_visible)
    return true;
  /* When address is taken, we don't know if equality comparison won't
     break eventually. Exception are virutal functions, C++
     constructors/destructors and vtables, where this is not possible by
     language standard.  */
  if (!DECL_VIRTUAL_P (node->decl)
      && (TREE_CODE (node->decl) != FUNCTION_DECL
	  || (!DECL_CXX_CONSTRUCTOR_P (node->decl)
	      && !DECL_CXX_DESTRUCTOR_P (node->decl)))
      && address_taken_from_non_vtable_p (node))
    return false;

  /* If the symbol is used in some weird way, better to not touch it.  */
  if (node->force_output)
    return false;

  /* Explicit instantiations needs to be output when possibly
     used externally.  */
  if (node->forced_by_abi
      && TREE_PUBLIC (node->decl)
      && (node->resolution != LDPR_PREVAILING_DEF_IRONLY
          && !flag_whole_program))
    return false;

  /* Non-readonly and volatile variables can not be duplicated.  */
  if (is_a <varpool_node> (node)
      && (!TREE_READONLY (node->decl)
	  || TREE_THIS_VOLATILE (node->decl)))
    return false;
  return true;
}

/* COMDAT functions must be shared only if they have address taken,
   otherwise we can produce our own private implementation with
   -fwhole-program.  
   Return true when turning COMDAT functoin static can not lead to wrong
   code when the resulting object links with a library defining same COMDAT.

   Virtual functions do have their addresses taken from the vtables,
   but in C++ there is no way to compare their addresses for equality.  */

static bool
comdat_can_be_unshared_p (symtab_node *node)
{
  if (!comdat_can_be_unshared_p_1 (node))
    return false;
  if (node->same_comdat_group)
    {
      symtab_node *next;

      /* If more than one function is in the same COMDAT group, it must
         be shared even if just one function in the comdat group has
         address taken.  */
      for (next = node->same_comdat_group;
	   next != node; next = next->same_comdat_group)
        if (!comdat_can_be_unshared_p_1 (next))
          return false;
    }
  return true;
}

/* Return true when function NODE should be considered externally visible.  */

static bool
cgraph_externally_visible_p (struct cgraph_node *node,
			     bool whole_program)
{
  if (!node->definition)
    return false;
  if (!TREE_PUBLIC (node->decl)
      || DECL_EXTERNAL (node->decl))
    return false;

  /* Do not try to localize built-in functions yet.  One of problems is that we
     end up mangling their asm for WHOPR that makes it impossible to call them
     using the implicit built-in declarations anymore.  Similarly this enables
     us to remove them as unreachable before actual calls may appear during
     expansion or folding.  */
  if (DECL_BUILT_IN (node->decl))
    return true;

  /* If linker counts on us, we must preserve the function.  */
  if (symtab_used_from_object_file_p (node))
    return true;
  if (DECL_PRESERVE_P (node->decl))
    return true;
  if (lookup_attribute ("externally_visible",
			DECL_ATTRIBUTES (node->decl)))
    return true;
  if (TARGET_DLLIMPORT_DECL_ATTRIBUTES
      && lookup_attribute ("dllexport",
			   DECL_ATTRIBUTES (node->decl)))
    return true;
  if (node->resolution == LDPR_PREVAILING_DEF_IRONLY)
    return false;
  /* When doing LTO or whole program, we can bring COMDAT functoins static.
     This improves code quality and we know we will duplicate them at most twice
     (in the case that we are not using plugin and link with object file
      implementing same COMDAT)  */
  if ((in_lto_p || whole_program)
      && DECL_COMDAT (node->decl)
      && comdat_can_be_unshared_p (node))
    return false;

  /* When doing link time optimizations, hidden symbols become local.  */
  if (in_lto_p
      && (DECL_VISIBILITY (node->decl) == VISIBILITY_HIDDEN
	  || DECL_VISIBILITY (node->decl) == VISIBILITY_INTERNAL)
      /* Be sure that node is defined in IR file, not in other object
	 file.  In that case we don't set used_from_other_object_file.  */
      && node->definition)
    ;
  else if (!whole_program)
    return true;

  if (MAIN_NAME_P (DECL_NAME (node->decl)))
    return true;

  return false;
}

/* Return true when variable VNODE should be considered externally visible.  */

bool
varpool_externally_visible_p (varpool_node *vnode)
{
  if (DECL_EXTERNAL (vnode->decl))
    return true;

  if (!TREE_PUBLIC (vnode->decl))
    return false;

  /* If linker counts on us, we must preserve the function.  */
  if (symtab_used_from_object_file_p (vnode))
    return true;

  if (DECL_HARD_REGISTER (vnode->decl))
    return true;
  if (DECL_PRESERVE_P (vnode->decl))
    return true;
  if (lookup_attribute ("externally_visible",
			DECL_ATTRIBUTES (vnode->decl)))
    return true;
  if (TARGET_DLLIMPORT_DECL_ATTRIBUTES
      && lookup_attribute ("dllexport",
			   DECL_ATTRIBUTES (vnode->decl)))
    return true;

  /* See if we have linker information about symbol not being used or
     if we need to make guess based on the declaration.

     Even if the linker clams the symbol is unused, never bring internal
     symbols that are declared by user as used or externally visible.
     This is needed for i.e. references from asm statements.   */
  if (symtab_used_from_object_file_p (vnode))
    return true;
  if (vnode->resolution == LDPR_PREVAILING_DEF_IRONLY)
    return false;

  /* As a special case, the COMDAT virtual tables can be unshared.
     In LTO mode turn vtables into static variables.  The variable is readonly,
     so this does not enable more optimization, but referring static var
     is faster for dynamic linking.  Also this match logic hidding vtables
     from LTO symbol tables.  */
  if ((in_lto_p || flag_whole_program)
      && DECL_COMDAT (vnode->decl)
      && comdat_can_be_unshared_p (vnode))
    return false;

  /* When doing link time optimizations, hidden symbols become local.  */
  if (in_lto_p
      && (DECL_VISIBILITY (vnode->decl) == VISIBILITY_HIDDEN
	  || DECL_VISIBILITY (vnode->decl) == VISIBILITY_INTERNAL)
      /* Be sure that node is defined in IR file, not in other object
	 file.  In that case we don't set used_from_other_object_file.  */
      && vnode->definition)
    ;
  else if (!flag_whole_program)
    return true;

  /* Do not attempt to privatize COMDATS by default.
     This would break linking with C++ libraries sharing
     inline definitions.

     FIXME: We can do so for readonly vars with no address taken and
     possibly also for vtables since no direct pointer comparsion is done.
     It might be interesting to do so to reduce linking overhead.  */
  if (DECL_COMDAT (vnode->decl) || DECL_WEAK (vnode->decl))
    return true;
  return false;
}

/* Return true if reference to NODE can be replaced by a local alias.
   Local aliases save dynamic linking overhead and enable more optimizations.
 */

bool
can_replace_by_local_alias (symtab_node *node)
{
  return (symtab_node_availability (node) > AVAIL_OVERWRITABLE
	  && !symtab_can_be_discarded (node));
}

/* Mark visibility of all functions.

   A local function is one whose calls can occur only in the current
   compilation unit and all its calls are explicit, so we can change
   its calling convention.  We simply mark all static functions whose
   address is not taken as local.

   We also change the TREE_PUBLIC flag of all declarations that are public
   in language point of view but we want to overwrite this default
   via visibilities for the backend point of view.  */

static unsigned int
function_and_variable_visibility (bool whole_program)
{
  struct cgraph_node *node;
  varpool_node *vnode;

  /* All aliases should be procssed at this point.  */
  gcc_checking_assert (!alias_pairs || !alias_pairs->length ());

  FOR_EACH_FUNCTION (node)
    {
      int flags = flags_from_decl_or_type (node->decl);

      /* Optimize away PURE and CONST constructors and destructors.  */
      if (optimize
	  && (flags & (ECF_CONST | ECF_PURE))
	  && !(flags & ECF_LOOPING_CONST_OR_PURE))
	{
	  DECL_STATIC_CONSTRUCTOR (node->decl) = 0;
	  DECL_STATIC_DESTRUCTOR (node->decl) = 0;
	}

      /* Frontends and alias code marks nodes as needed before parsing is finished.
	 We may end up marking as node external nodes where this flag is meaningless
	 strip it.  */
      if (DECL_EXTERNAL (node->decl) || !node->definition)
	{
	  node->force_output = 0;
	  node->forced_by_abi = 0;
	}

      /* C++ FE on lack of COMDAT support create local COMDAT functions
	 (that ought to be shared but can not due to object format
	 limitations).  It is necessary to keep the flag to make rest of C++ FE
	 happy.  Clear the flag here to avoid confusion in middle-end.  */
      if (DECL_COMDAT (node->decl) && !TREE_PUBLIC (node->decl))
        DECL_COMDAT (node->decl) = 0;

      /* For external decls stop tracking same_comdat_group. It doesn't matter
	 what comdat group they are in when they won't be emitted in this TU.  */
      if (node->same_comdat_group && DECL_EXTERNAL (node->decl))
	{
#ifdef ENABLE_CHECKING
	  symtab_node *n;

	  for (n = node->same_comdat_group;
	       n != node;
	       n = n->same_comdat_group)
	      /* If at least one of same comdat group functions is external,
		 all of them have to be, otherwise it is a front-end bug.  */
	      gcc_assert (DECL_EXTERNAL (n->decl));
#endif
	  symtab_dissolve_same_comdat_group_list (node);
	}
      gcc_assert ((!DECL_WEAK (node->decl)
		  && !DECL_COMDAT (node->decl))
      	          || TREE_PUBLIC (node->decl)
		  || node->weakref
		  || DECL_EXTERNAL (node->decl));
      if (cgraph_externally_visible_p (node, whole_program))
        {
	  gcc_assert (!node->global.inlined_to);
	  node->externally_visible = true;
	}
      else
	{
	  node->externally_visible = false;
	  node->forced_by_abi = false;
	}
      if (!node->externally_visible
	  && node->definition && !node->weakref
	  && !DECL_EXTERNAL (node->decl))
	{
	  gcc_assert (whole_program || in_lto_p
		      || !TREE_PUBLIC (node->decl));
	  node->unique_name = ((node->resolution == LDPR_PREVAILING_DEF_IRONLY
				|| node->unique_name
				|| node->resolution == LDPR_PREVAILING_DEF_IRONLY_EXP)
				&& TREE_PUBLIC (node->decl));
	  node->resolution = LDPR_PREVAILING_DEF_IRONLY;
	  if (node->same_comdat_group && TREE_PUBLIC (node->decl))
	    {
	      symtab_node *next = node;

	      /* Set all members of comdat group local.  */
	      if (node->same_comdat_group)
		for (next = node->same_comdat_group;
		     next != node;
		     next = next->same_comdat_group)
		{
		  symtab_make_decl_local (next->decl);
		  next->unique_name = ((next->resolution == LDPR_PREVAILING_DEF_IRONLY
					|| next->unique_name
					|| next->resolution == LDPR_PREVAILING_DEF_IRONLY_EXP)
					&& TREE_PUBLIC (next->decl));
		}
	      /* cgraph_externally_visible_p has already checked all other nodes
	         in the group and they will all be made local.  We need to
	         dissolve the group at once so that the predicate does not
	         segfault though. */
	      symtab_dissolve_same_comdat_group_list (node);
	    }
	  symtab_make_decl_local (node->decl);
	}

      if (node->thunk.thunk_p
	  && TREE_PUBLIC (node->decl))
	{
	  struct cgraph_node *decl_node = node;

	  decl_node = cgraph_function_node (decl_node->callees->callee, NULL);

	  /* Thunks have the same visibility as function they are attached to.
	     Make sure the C++ front end set this up properly.  */
	  if (DECL_ONE_ONLY (decl_node->decl))
	    {
	      gcc_checking_assert (DECL_COMDAT (node->decl)
				   == DECL_COMDAT (decl_node->decl));
	      gcc_checking_assert (DECL_COMDAT_GROUP (node->decl)
				   == DECL_COMDAT_GROUP (decl_node->decl));
	      gcc_checking_assert (node->same_comdat_group);
	    }
	  node->forced_by_abi = decl_node->forced_by_abi;
	  if (DECL_EXTERNAL (decl_node->decl))
	    DECL_EXTERNAL (node->decl) = 1;
	}

      /* If whole comdat group is used only within LTO code, we can dissolve it,
	 we handle the unification ourselves.
	 We keep COMDAT and weak so visibility out of DSO does not change.
	 Later we may bring the symbols static if they are not exported.  */
      if (DECL_ONE_ONLY (node->decl)
	  && (node->resolution == LDPR_PREVAILING_DEF_IRONLY
	      || node->resolution == LDPR_PREVAILING_DEF_IRONLY_EXP))
	{
	  symtab_node *next = node;

	  if (node->same_comdat_group)
	    for (next = node->same_comdat_group;
		 next != node;
		 next = next->same_comdat_group)
	      if (next->externally_visible
		  && (next->resolution != LDPR_PREVAILING_DEF_IRONLY
		      && next->resolution != LDPR_PREVAILING_DEF_IRONLY_EXP))
		break;
	  if (node == next)
	    {
	      if (node->same_comdat_group)
	        for (next = node->same_comdat_group;
		     next != node;
		     next = next->same_comdat_group)
		{
		  DECL_COMDAT_GROUP (next->decl) = NULL;
		  DECL_WEAK (next->decl) = false;
		}
	      DECL_COMDAT_GROUP (node->decl) = NULL;
	      symtab_dissolve_same_comdat_group_list (node);
	    }
	}
    }
  FOR_EACH_DEFINED_FUNCTION (node)
    {
      node->local.local |= cgraph_local_node_p (node);

      /* If we know that function can not be overwritten by a different semantics
	 and moreover its section can not be discarded, replace all direct calls
	 by calls to an nonoverwritable alias.  This make dynamic linking
	 cheaper and enable more optimization.

	 TODO: We can also update virtual tables.  */
      if (node->callers && can_replace_by_local_alias (node))
	{
	  struct cgraph_node *alias = cgraph (symtab_nonoverwritable_alias (node));
	  struct cgraph_edge *e, *next_caller;

	  if (alias && alias != node)
	    {
              for (e = node->callers; e; e = next_caller)
		{
                  next_caller = e->next_caller;
		  if (L_IPO_COMP_MODE && cgraph_is_fake_indirect_call_edge (e))
		    continue;

		  cgraph_redirect_edge_callee (e, alias);
		  if (gimple_has_body_p (e->caller->decl))
		    {
		      push_cfun (DECL_STRUCT_FUNCTION (e->caller->decl));
		      cgraph_redirect_edge_call_stmt_to_callee (e);
		      pop_cfun ();
		    }
		}
	    }
	}
    }
  FOR_EACH_VARIABLE (vnode)
    {
      /* weak flag makes no sense on local variables.  */
      gcc_assert (!DECL_WEAK (vnode->decl)
		  || vnode->weakref
      		  || TREE_PUBLIC (vnode->decl)
		  || DECL_EXTERNAL (vnode->decl));
      /* In several cases declarations can not be common:

	 - when declaration has initializer
	 - when it is in weak
	 - when it has specific section
	 - when it resides in non-generic address space.
	 - if declaration is local, it will get into .local common section
	   so common flag is not needed.  Frontends still produce these in
	   certain cases, such as for:

	     static int a __attribute__ ((common))

	 Canonicalize things here and clear the redundant flag.  */
      if (DECL_COMMON (vnode->decl)
	  && (!(TREE_PUBLIC (vnode->decl)
	      || DECL_EXTERNAL (vnode->decl))
	      || (DECL_INITIAL (vnode->decl)
		  && DECL_INITIAL (vnode->decl) != error_mark_node)
	      || DECL_WEAK (vnode->decl)
	      || DECL_SECTION_NAME (vnode->decl) != NULL
	      || ! (ADDR_SPACE_GENERIC_P
		    (TYPE_ADDR_SPACE (TREE_TYPE (vnode->decl))))))
	DECL_COMMON (vnode->decl) = 0;
    }
  FOR_EACH_DEFINED_VARIABLE (vnode)
    {
      if (!vnode->definition)
        continue;
      if (varpool_externally_visible_p (vnode))
	vnode->externally_visible = true;
      else
	{
          vnode->externally_visible = false;
	  vnode->forced_by_abi = false;
	}
      if (!vnode->externally_visible
	  && !vnode->weakref)
	{
	  gcc_assert (in_lto_p || whole_program || !TREE_PUBLIC (vnode->decl));
	  vnode->unique_name = ((vnode->resolution == LDPR_PREVAILING_DEF_IRONLY
				       || vnode->resolution == LDPR_PREVAILING_DEF_IRONLY_EXP)
				       && TREE_PUBLIC (vnode->decl));
	  symtab_make_decl_local (vnode->decl);
	  if (vnode->same_comdat_group)
	    symtab_dissolve_same_comdat_group_list (vnode);
	  vnode->resolution = LDPR_PREVAILING_DEF_IRONLY;
	}
      /* Static variables defined in auxiliary modules are externalized to
         allow cross module inlining.  */
      gcc_assert (TREE_STATIC (vnode->decl)
                  || varpool_is_auxiliary (vnode));
    }

  if (dump_file)
    {
      fprintf (dump_file, "\nMarking local functions:");
      FOR_EACH_DEFINED_FUNCTION (node)
	if (node->local.local)
	  fprintf (dump_file, " %s", node->name ());
      fprintf (dump_file, "\n\n");
      fprintf (dump_file, "\nMarking externally visible functions:");
      FOR_EACH_DEFINED_FUNCTION (node)
	if (node->externally_visible)
	  fprintf (dump_file, " %s", node->name ());
      fprintf (dump_file, "\n\n");
      fprintf (dump_file, "\nMarking externally visible variables:");
      FOR_EACH_DEFINED_VARIABLE (vnode)
	if (vnode->externally_visible)
	  fprintf (dump_file, " %s", vnode->name ());
      fprintf (dump_file, "\n\n");
    }
  cgraph_function_flags_ready = true;
  return 0;
}

/* Local function pass handling visibilities.  This happens before LTO streaming
   so in particular -fwhole-program should be ignored at this level.  */

static unsigned int
local_function_and_variable_visibility (void)
{
  return function_and_variable_visibility (flag_whole_program && !flag_lto);
}

namespace {

const pass_data pass_data_ipa_function_and_variable_visibility =
{
  SIMPLE_IPA_PASS, /* type */
  "visibility", /* name */
  OPTGROUP_NONE, /* optinfo_flags */
  false, /* has_gate */
  true, /* has_execute */
  TV_CGRAPHOPT, /* tv_id */
  0, /* properties_required */
  0, /* properties_provided */
  0, /* properties_destroyed */
  0, /* todo_flags_start */
  ( TODO_remove_functions | TODO_dump_symtab ), /* todo_flags_finish */
};

class pass_ipa_function_and_variable_visibility : public simple_ipa_opt_pass
{
public:
  pass_ipa_function_and_variable_visibility (gcc::context *ctxt)
    : simple_ipa_opt_pass (pass_data_ipa_function_and_variable_visibility,
			   ctxt)
  {}

  /* opt_pass methods: */
  unsigned int execute () {
    return local_function_and_variable_visibility ();
  }

}; // class pass_ipa_function_and_variable_visibility

} // anon namespace

simple_ipa_opt_pass *
make_pass_ipa_function_and_variable_visibility (gcc::context *ctxt)
{
  return new pass_ipa_function_and_variable_visibility (ctxt);
}

/* Free inline summary.  */

static unsigned
free_inline_summary (void)
{
  inline_free_summary ();
  return 0;
}

namespace {

const pass_data pass_data_ipa_free_inline_summary =
{
  SIMPLE_IPA_PASS, /* type */
  "*free_inline_summary", /* name */
  OPTGROUP_NONE, /* optinfo_flags */
  false, /* has_gate */
  true, /* has_execute */
  TV_IPA_FREE_INLINE_SUMMARY, /* tv_id */
  0, /* properties_required */
  0, /* properties_provided */
  0, /* properties_destroyed */
  0, /* todo_flags_start */
  0, /* todo_flags_finish */
};

class pass_ipa_free_inline_summary : public simple_ipa_opt_pass
{
public:
  pass_ipa_free_inline_summary (gcc::context *ctxt)
    : simple_ipa_opt_pass (pass_data_ipa_free_inline_summary, ctxt)
  {}

  /* opt_pass methods: */
  unsigned int execute () { return free_inline_summary (); }

}; // class pass_ipa_free_inline_summary

} // anon namespace

simple_ipa_opt_pass *
make_pass_ipa_free_inline_summary (gcc::context *ctxt)
{
  return new pass_ipa_free_inline_summary (ctxt);
}

/* Do not re-run on ltrans stage.  */

static bool
gate_whole_program_function_and_variable_visibility (void)
{
  return !flag_ltrans;
}

/* Bring functionss local at LTO time with -fwhole-program.  */

static unsigned int
whole_program_function_and_variable_visibility (void)
{
  function_and_variable_visibility (flag_whole_program);
  if (optimize)
    ipa_discover_readonly_nonaddressable_vars ();
  return 0;
}

namespace {

const pass_data pass_data_ipa_whole_program_visibility =
{
  IPA_PASS, /* type */
  "whole-program", /* name */
  OPTGROUP_NONE, /* optinfo_flags */
  true, /* has_gate */
  true, /* has_execute */
  TV_CGRAPHOPT, /* tv_id */
  0, /* properties_required */
  0, /* properties_provided */
  0, /* properties_destroyed */
  0, /* todo_flags_start */
  ( TODO_remove_functions | TODO_dump_symtab ), /* todo_flags_finish */
};

class pass_ipa_whole_program_visibility : public ipa_opt_pass_d
{
public:
  pass_ipa_whole_program_visibility (gcc::context *ctxt)
    : ipa_opt_pass_d (pass_data_ipa_whole_program_visibility, ctxt,
		      NULL, /* generate_summary */
		      NULL, /* write_summary */
		      NULL, /* read_summary */
		      NULL, /* write_optimization_summary */
		      NULL, /* read_optimization_summary */
		      NULL, /* stmt_fixup */
		      0, /* function_transform_todo_flags_start */
		      NULL, /* function_transform */
		      NULL) /* variable_transform */
  {}

  /* opt_pass methods: */
  bool gate () {
    return gate_whole_program_function_and_variable_visibility ();
  }
  unsigned int execute () {
    return whole_program_function_and_variable_visibility ();
  }

}; // class pass_ipa_whole_program_visibility

} // anon namespace

ipa_opt_pass_d *
make_pass_ipa_whole_program_visibility (gcc::context *ctxt)
{
  return new pass_ipa_whole_program_visibility (ctxt);
}

/* Generate and emit a static constructor or destructor.  WHICH must
   be one of 'I' (for a constructor) or 'D' (for a destructor).  BODY
   is a STATEMENT_LIST containing GENERIC statements.  PRIORITY is the
   initialization priority for this constructor or destructor. 

   FINAL specify whether the externally visible name for collect2 should
   be produced. */

static void
cgraph_build_static_cdtor_1 (char which, tree body, int priority, bool final)
{
  static int counter = 0;
  char which_buf[16];
  tree decl, name, resdecl;

  /* The priority is encoded in the constructor or destructor name.
     collect2 will sort the names and arrange that they are called at
     program startup.  */
  if (final)
    sprintf (which_buf, "%c_%.5d_%d", which, priority, counter++);
  else
  /* Proudce sane name but one not recognizable by collect2, just for the
     case we fail to inline the function.  */
    sprintf (which_buf, "sub_%c_%.5d_%d", which, priority, counter++);
  name = get_file_function_name (which_buf);

  decl = build_decl (input_location, FUNCTION_DECL, name,
		     build_function_type_list (void_type_node, NULL_TREE));
  current_function_decl = decl;

  resdecl = build_decl (input_location,
			RESULT_DECL, NULL_TREE, void_type_node);
  DECL_ARTIFICIAL (resdecl) = 1;
  DECL_RESULT (decl) = resdecl;
  DECL_CONTEXT (resdecl) = decl;

  allocate_struct_function (decl, false);

  TREE_STATIC (decl) = 1;
  TREE_USED (decl) = 1;
  DECL_ARTIFICIAL (decl) = 1;
  DECL_NO_INSTRUMENT_FUNCTION_ENTRY_EXIT (decl) = 1;
  DECL_SAVED_TREE (decl) = body;
  if (!targetm.have_ctors_dtors && final)
    {
      TREE_PUBLIC (decl) = 1;
      DECL_PRESERVE_P (decl) = 1;
    }
  DECL_UNINLINABLE (decl) = 1;

  DECL_INITIAL (decl) = make_node (BLOCK);
  TREE_USED (DECL_INITIAL (decl)) = 1;

  DECL_SOURCE_LOCATION (decl) = input_location;
  cfun->function_end_locus = input_location;

  switch (which)
    {
    case 'I':
      DECL_STATIC_CONSTRUCTOR (decl) = 1;
      decl_init_priority_insert (decl, priority);
      break;
    case 'D':
      DECL_STATIC_DESTRUCTOR (decl) = 1;
      decl_fini_priority_insert (decl, priority);
      break;
    default:
      gcc_unreachable ();
    }

  gimplify_function_tree (decl);

  cgraph_add_new_function (decl, false);

  set_cfun (NULL);
  current_function_decl = NULL;
}

/* Generate and emit a static constructor or destructor.  WHICH must
   be one of 'I' (for a constructor) or 'D' (for a destructor).  BODY
   is a STATEMENT_LIST containing GENERIC statements.  PRIORITY is the
   initialization priority for this constructor or destructor.  */

void
cgraph_build_static_cdtor (char which, tree body, int priority)
{
  cgraph_build_static_cdtor_1 (which, body, priority, false);
}

/* A vector of FUNCTION_DECLs declared as static constructors.  */
static vec<tree> static_ctors;
/* A vector of FUNCTION_DECLs declared as static destructors.  */
static vec<tree> static_dtors;

/* When target does not have ctors and dtors, we call all constructor
   and destructor by special initialization/destruction function
   recognized by collect2.

   When we are going to build this function, collect all constructors and
   destructors and turn them into normal functions.  */

static void
record_cdtor_fn (struct cgraph_node *node)
{
  if (DECL_STATIC_CONSTRUCTOR (node->decl))
    static_ctors.safe_push (node->decl);
  if (DECL_STATIC_DESTRUCTOR (node->decl))
    static_dtors.safe_push (node->decl);
  node = cgraph_get_node (node->decl);
  DECL_DISREGARD_INLINE_LIMITS (node->decl) = 1;
}

/* Define global constructors/destructor functions for the CDTORS, of
   which they are LEN.  The CDTORS are sorted by initialization
   priority.  If CTOR_P is true, these are constructors; otherwise,
   they are destructors.  */

static void
build_cdtor (bool ctor_p, vec<tree> cdtors)
{
  size_t i,j;
  size_t len = cdtors.length ();

  i = 0;
  while (i < len)
    {
      tree body;
      tree fn;
      priority_type priority;

      priority = 0;
      body = NULL_TREE;
      j = i;
      do
	{
	  priority_type p;
	  fn = cdtors[j];
	  p = ctor_p ? DECL_INIT_PRIORITY (fn) : DECL_FINI_PRIORITY (fn);
	  if (j == i)
	    priority = p;
	  else if (p != priority)
	    break;
	  j++;
	}
      while (j < len);

      /* When there is only one cdtor and target supports them, do nothing.  */
      if (j == i + 1
	  && targetm.have_ctors_dtors)
	{
	  i++;
	  continue;
	}
      /* Find the next batch of constructors/destructors with the same
	 initialization priority.  */
      for (;i < j; i++)
	{
	  tree call;
	  fn = cdtors[i];
	  call = build_call_expr (fn, 0);
	  if (ctor_p)
	    DECL_STATIC_CONSTRUCTOR (fn) = 0;
	  else
	    DECL_STATIC_DESTRUCTOR (fn) = 0;
	  /* We do not want to optimize away pure/const calls here.
	     When optimizing, these should be already removed, when not
	     optimizing, we want user to be able to breakpoint in them.  */
	  TREE_SIDE_EFFECTS (call) = 1;
	  append_to_statement_list (call, &body);
	}
      gcc_assert (body != NULL_TREE);
      /* Generate a function to call all the function of like
	 priority.  */
      cgraph_build_static_cdtor_1 (ctor_p ? 'I' : 'D', body, priority, true);
    }
}

/* Comparison function for qsort.  P1 and P2 are actually of type
   "tree *" and point to static constructors.  DECL_INIT_PRIORITY is
   used to determine the sort order.  */

static int
compare_ctor (const void *p1, const void *p2)
{
  tree f1;
  tree f2;
  int priority1;
  int priority2;

  f1 = *(const tree *)p1;
  f2 = *(const tree *)p2;
  priority1 = DECL_INIT_PRIORITY (f1);
  priority2 = DECL_INIT_PRIORITY (f2);

  if (priority1 < priority2)
    return -1;
  else if (priority1 > priority2)
    return 1;
  else
    /* Ensure a stable sort.  Constructors are executed in backwarding
       order to make LTO initialize braries first.  */
    return DECL_UID (f2) - DECL_UID (f1);
}

/* Comparison function for qsort.  P1 and P2 are actually of type
   "tree *" and point to static destructors.  DECL_FINI_PRIORITY is
   used to determine the sort order.  */

static int
compare_dtor (const void *p1, const void *p2)
{
  tree f1;
  tree f2;
  int priority1;
  int priority2;

  f1 = *(const tree *)p1;
  f2 = *(const tree *)p2;
  priority1 = DECL_FINI_PRIORITY (f1);
  priority2 = DECL_FINI_PRIORITY (f2);

  if (priority1 < priority2)
    return -1;
  else if (priority1 > priority2)
    return 1;
  else
    /* Ensure a stable sort.  */
    return DECL_UID (f1) - DECL_UID (f2);
}

/* Generate functions to call static constructors and destructors
   for targets that do not support .ctors/.dtors sections.  These
   functions have magic names which are detected by collect2.  */

static void
build_cdtor_fns (void)
{
  if (!static_ctors.is_empty ())
    {
      gcc_assert (!targetm.have_ctors_dtors || in_lto_p);
      static_ctors.qsort (compare_ctor);
      build_cdtor (/*ctor_p=*/true, static_ctors);
    }

  if (!static_dtors.is_empty ())
    {
      gcc_assert (!targetm.have_ctors_dtors || in_lto_p);
      static_dtors.qsort (compare_dtor);
      build_cdtor (/*ctor_p=*/false, static_dtors);
    }
}

/* Look for constructors and destructors and produce function calling them.
   This is needed for targets not supporting ctors or dtors, but we perform the
   transformation also at linktime to merge possibly numerous
   constructors/destructors into single function to improve code locality and
   reduce size.  */

static unsigned int
ipa_cdtor_merge (void)
{
  struct cgraph_node *node;
  FOR_EACH_DEFINED_FUNCTION (node)
    if (DECL_STATIC_CONSTRUCTOR (node->decl)
	|| DECL_STATIC_DESTRUCTOR (node->decl))
       record_cdtor_fn (node);
  build_cdtor_fns ();
  static_ctors.release ();
  static_dtors.release ();
  return 0;
}

/* Perform the pass when we have no ctors/dtors support
   or at LTO time to merge multiple constructors into single
   function.  */

static bool
gate_ipa_cdtor_merge (void)
{
  return !targetm.have_ctors_dtors || (optimize && in_lto_p);
}

namespace {

const pass_data pass_data_ipa_cdtor_merge =
{
  IPA_PASS, /* type */
  "cdtor", /* name */
  OPTGROUP_NONE, /* optinfo_flags */
  true, /* has_gate */
  true, /* has_execute */
  TV_CGRAPHOPT, /* tv_id */
  0, /* properties_required */
  0, /* properties_provided */
  0, /* properties_destroyed */
  0, /* todo_flags_start */
  0, /* todo_flags_finish */
};

class pass_ipa_cdtor_merge : public ipa_opt_pass_d
{
public:
  pass_ipa_cdtor_merge (gcc::context *ctxt)
    : ipa_opt_pass_d (pass_data_ipa_cdtor_merge, ctxt,
		      NULL, /* generate_summary */
		      NULL, /* write_summary */
		      NULL, /* read_summary */
		      NULL, /* write_optimization_summary */
		      NULL, /* read_optimization_summary */
		      NULL, /* stmt_fixup */
		      0, /* function_transform_todo_flags_start */
		      NULL, /* function_transform */
		      NULL) /* variable_transform */
  {}

  /* opt_pass methods: */
  bool gate () { return gate_ipa_cdtor_merge (); }
  unsigned int execute () { return ipa_cdtor_merge (); }

}; // class pass_ipa_cdtor_merge

} // anon namespace

ipa_opt_pass_d *
make_pass_ipa_cdtor_merge (gcc::context *ctxt)
{
  return new pass_ipa_cdtor_merge (ctxt);
}