summaryrefslogtreecommitdiff
path: root/gcc/ipa-pure-const.c
blob: c221cd0a3babf94a2beaff3e8f4fb5f8c2052f48 (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
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
/* Callgraph based analysis of static variables.
   Copyright (C) 2004-2014 Free Software Foundation, Inc.
   Contributed by Kenneth Zadeck <zadeck@naturalbridge.com>

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/>.  */

/* This file marks functions as being either const (TREE_READONLY) or
   pure (DECL_PURE_P).  It can also set a variant of these that
   are allowed to loop indefinitely (DECL_LOOPING_CONST_PURE_P).

   This must be run after inlining decisions have been made since
   otherwise, the local sets will not contain information that is
   consistent with post inlined state.  The global sets are not prone
   to this problem since they are by definition transitive.  */

/* The code in this module is called by the ipa pass manager. It
   should be one of the later passes since it's information is used by
   the rest of the compilation. */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "print-tree.h"
#include "calls.h"
#include "basic-block.h"
#include "tree-ssa-alias.h"
#include "internal-fn.h"
#include "tree-eh.h"
#include "gimple-expr.h"
#include "is-a.h"
#include "gimple.h"
#include "gimple-iterator.h"
#include "gimple-walk.h"
#include "tree-cfg.h"
#include "tree-ssa-loop-niter.h"
#include "tree-inline.h"
#include "tree-pass.h"
#include "langhooks.h"
#include "ipa-utils.h"
#include "flags.h"
#include "diagnostic.h"
#include "gimple-pretty-print.h"
#include "langhooks.h"
#include "target.h"
#include "lto-streamer.h"
#include "data-streamer.h"
#include "tree-streamer.h"
#include "cfgloop.h"
#include "tree-scalar-evolution.h"
#include "intl.h"
#include "opts.h"
#include "hash-set.h"

/* Lattice values for const and pure functions.  Everything starts out
   being const, then may drop to pure and then neither depending on
   what is found.  */
enum pure_const_state_e
{
  IPA_CONST,
  IPA_PURE,
  IPA_NEITHER
};

const char *pure_const_names[3] = {"const", "pure", "neither"};

/* Holder for the const_state.  There is one of these per function
   decl.  */
struct funct_state_d
{
  /* See above.  */
  enum pure_const_state_e pure_const_state;
  /* What user set here; we can be always sure about this.  */
  enum pure_const_state_e state_previously_known;
  bool looping_previously_known;

  /* True if the function could possibly infinite loop.  There are a
     lot of ways that this could be determined.  We are pretty
     conservative here.  While it is possible to cse pure and const
     calls, it is not legal to have dce get rid of the call if there
     is a possibility that the call could infinite loop since this is
     a behavioral change.  */
  bool looping;

  bool can_throw;
};

/* State used when we know nothing about function.  */
static struct funct_state_d varying_state
   = { IPA_NEITHER, IPA_NEITHER, true, true, true };


typedef struct funct_state_d * funct_state;

/* The storage of the funct_state is abstracted because there is the
   possibility that it may be desirable to move this to the cgraph
   local info.  */

/* Array, indexed by cgraph node uid, of function states.  */

static vec<funct_state> funct_state_vec;

static bool gate_pure_const (void);

namespace {

const pass_data pass_data_ipa_pure_const =
{
  IPA_PASS, /* type */
  "pure-const", /* name */
  OPTGROUP_NONE, /* optinfo_flags */
  TV_IPA_PURE_CONST, /* tv_id */
  0, /* properties_required */
  0, /* properties_provided */
  0, /* properties_destroyed */
  0, /* todo_flags_start */
  0, /* todo_flags_finish */
};

class pass_ipa_pure_const : public ipa_opt_pass_d
{
public:
  pass_ipa_pure_const(gcc::context *ctxt);

  /* opt_pass methods: */
  bool gate (function *) { return gate_pure_const (); }
  unsigned int execute (function *fun);

  void register_hooks (void);

private:
  bool init_p;

  /* Holders of ipa cgraph hooks: */
  struct cgraph_node_hook_list *function_insertion_hook_holder;
  struct cgraph_2node_hook_list *node_duplication_hook_holder;
  struct cgraph_node_hook_list *node_removal_hook_holder;

}; // class pass_ipa_pure_const

} // anon namespace

/* Try to guess if function body will always be visible to compiler
   when compiling the call and whether compiler will be able
   to propagate the information by itself.  */

static bool
function_always_visible_to_compiler_p (tree decl)
{
  return (!TREE_PUBLIC (decl) || DECL_DECLARED_INLINE_P (decl));
}

/* Emit suggestion about attribute ATTRIB_NAME for DECL.  KNOWN_FINITE
   is true if the function is known to be finite.  The diagnostic is
   controlled by OPTION.  WARNED_ABOUT is a hash_set<tree> unique for
   OPTION, this function may initialize it and it is always returned
   by the function.  */

static hash_set<tree> *
suggest_attribute (int option, tree decl, bool known_finite,
		   hash_set<tree> *warned_about,
		   const char * attrib_name)
{
  if (!option_enabled (option, &global_options))
    return warned_about;
  if (TREE_THIS_VOLATILE (decl)
      || (known_finite && function_always_visible_to_compiler_p (decl)))
    return warned_about;

  if (!warned_about)
    warned_about = new hash_set<tree>;
  if (warned_about->contains (decl))
    return warned_about;
  warned_about->add (decl);
  warning_at (DECL_SOURCE_LOCATION (decl),
	      option,
	      known_finite
	      ? _("function might be candidate for attribute %<%s%>")
	      : _("function might be candidate for attribute %<%s%>"
		  " if it is known to return normally"), attrib_name);
  return warned_about;
}

/* Emit suggestion about __attribute_((pure)) for DECL.  KNOWN_FINITE
   is true if the function is known to be finite.  */

static void
warn_function_pure (tree decl, bool known_finite)
{
  static hash_set<tree> *warned_about;

  warned_about 
    = suggest_attribute (OPT_Wsuggest_attribute_pure, decl,
			 known_finite, warned_about, "pure");
}

/* Emit suggestion about __attribute_((const)) for DECL.  KNOWN_FINITE
   is true if the function is known to be finite.  */

static void
warn_function_const (tree decl, bool known_finite)
{
  static hash_set<tree> *warned_about;
  warned_about 
    = suggest_attribute (OPT_Wsuggest_attribute_const, decl,
			 known_finite, warned_about, "const");
}

static void
warn_function_noreturn (tree decl)
{
  static hash_set<tree> *warned_about;
  if (!lang_hooks.missing_noreturn_ok_p (decl)
      && targetm.warn_func_return (decl))
    warned_about 
      = suggest_attribute (OPT_Wsuggest_attribute_noreturn, decl,
			   true, warned_about, "noreturn");
}

/* Return true if we have a function state for NODE.  */

static inline bool
has_function_state (struct cgraph_node *node)
{
  if (!funct_state_vec.exists ()
      || funct_state_vec.length () <= (unsigned int)node->uid)
    return false;
  return funct_state_vec[node->uid] != NULL;
}

/* Return the function state from NODE.  */

static inline funct_state
get_function_state (struct cgraph_node *node)
{
  if (!funct_state_vec.exists ()
      || funct_state_vec.length () <= (unsigned int)node->uid
      || !funct_state_vec[node->uid])
    /* We might want to put correct previously_known state into varying.  */
    return &varying_state;
 return funct_state_vec[node->uid];
}

/* Set the function state S for NODE.  */

static inline void
set_function_state (struct cgraph_node *node, funct_state s)
{
  if (!funct_state_vec.exists ()
      || funct_state_vec.length () <= (unsigned int)node->uid)
     funct_state_vec.safe_grow_cleared (node->uid + 1);
  funct_state_vec[node->uid] = s;
}

/* Check to see if the use (or definition when CHECKING_WRITE is true)
   variable T is legal in a function that is either pure or const.  */

static inline void
check_decl (funct_state local,
	    tree t, bool checking_write, bool ipa)
{
  /* Do not want to do anything with volatile except mark any
     function that uses one to be not const or pure.  */
  if (TREE_THIS_VOLATILE (t))
    {
      local->pure_const_state = IPA_NEITHER;
      if (dump_file)
        fprintf (dump_file, "    Volatile operand is not const/pure");
      return;
    }

  /* Do not care about a local automatic that is not static.  */
  if (!TREE_STATIC (t) && !DECL_EXTERNAL (t))
    return;

  /* If the variable has the "used" attribute, treat it as if it had a
     been touched by the devil.  */
  if (DECL_PRESERVE_P (t))
    {
      local->pure_const_state = IPA_NEITHER;
      if (dump_file)
        fprintf (dump_file, "    Used static/global variable is not const/pure\n");
      return;
    }

  /* In IPA mode we are not interested in checking actual loads and stores;
     they will be processed at propagation time using ipa_ref.  */
  if (ipa)
    return;

  /* Since we have dealt with the locals and params cases above, if we
     are CHECKING_WRITE, this cannot be a pure or constant
     function.  */
  if (checking_write)
    {
      local->pure_const_state = IPA_NEITHER;
      if (dump_file)
        fprintf (dump_file, "    static/global memory write is not const/pure\n");
      return;
    }

  if (DECL_EXTERNAL (t) || TREE_PUBLIC (t))
    {
      /* Readonly reads are safe.  */
      if (TREE_READONLY (t) && !TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (t)))
	return; /* Read of a constant, do not change the function state.  */
      else
	{
          if (dump_file)
            fprintf (dump_file, "    global memory read is not const\n");
	  /* Just a regular read.  */
	  if (local->pure_const_state == IPA_CONST)
	    local->pure_const_state = IPA_PURE;
	}
    }
  else
    {
      /* Compilation level statics can be read if they are readonly
	 variables.  */
      if (TREE_READONLY (t))
	return;

      if (dump_file)
	fprintf (dump_file, "    static memory read is not const\n");
      /* Just a regular read.  */
      if (local->pure_const_state == IPA_CONST)
	local->pure_const_state = IPA_PURE;
    }
}


/* Check to see if the use (or definition when CHECKING_WRITE is true)
   variable T is legal in a function that is either pure or const.  */

static inline void
check_op (funct_state local, tree t, bool checking_write)
{
  t = get_base_address (t);
  if (t && TREE_THIS_VOLATILE (t))
    {
      local->pure_const_state = IPA_NEITHER;
      if (dump_file)
	fprintf (dump_file, "    Volatile indirect ref is not const/pure\n");
      return;
    }
  else if (t
  	   && (INDIRECT_REF_P (t) || TREE_CODE (t) == MEM_REF)
	   && TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME
	   && !ptr_deref_may_alias_global_p (TREE_OPERAND (t, 0)))
    {
      if (dump_file)
	fprintf (dump_file, "    Indirect ref to local memory is OK\n");
      return;
    }
  else if (checking_write)
    {
      local->pure_const_state = IPA_NEITHER;
      if (dump_file)
	fprintf (dump_file, "    Indirect ref write is not const/pure\n");
      return;
    }
  else
    {
      if (dump_file)
	fprintf (dump_file, "    Indirect ref read is not const\n");
      if (local->pure_const_state == IPA_CONST)
	local->pure_const_state = IPA_PURE;
    }
}

/* compute state based on ECF FLAGS and store to STATE and LOOPING.  */

static void
state_from_flags (enum pure_const_state_e *state, bool *looping,
	          int flags, bool cannot_lead_to_return)
{
  *looping = false;
  if (flags & ECF_LOOPING_CONST_OR_PURE)
    {
      *looping = true;
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, " looping");
    }
  if (flags & ECF_CONST)
    {
      *state = IPA_CONST;
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, " const\n");
    }
  else if (flags & ECF_PURE)
    {
      *state = IPA_PURE;
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, " pure\n");
    }
  else if (cannot_lead_to_return)
    {
      *state = IPA_PURE;
      *looping = true;
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, " ignoring side effects->pure looping\n");
    }
  else
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, " neither\n");
      *state = IPA_NEITHER;
      *looping = true;
    }
}

/* Merge STATE and STATE2 and LOOPING and LOOPING2 and store
   into STATE and LOOPING better of the two variants.
   Be sure to merge looping correctly.  IPA_NEITHER functions
   have looping 0 even if they don't have to return.  */

static inline void
better_state (enum pure_const_state_e *state, bool *looping,
	      enum pure_const_state_e state2, bool looping2)
{
  if (state2 < *state)
    {
      if (*state == IPA_NEITHER)
	*looping = looping2;
      else
	*looping = MIN (*looping, looping2);
      *state = state2;
    }
  else if (state2 != IPA_NEITHER)
    *looping = MIN (*looping, looping2);
}

/* Merge STATE and STATE2 and LOOPING and LOOPING2 and store
   into STATE and LOOPING worse of the two variants.  */

static inline void
worse_state (enum pure_const_state_e *state, bool *looping,
	     enum pure_const_state_e state2, bool looping2)
{
  *state = MAX (*state, state2);
  *looping = MAX (*looping, looping2);
}

/* Recognize special cases of builtins that are by themselves not pure or const
   but function using them is.  */
static bool
special_builtin_state (enum pure_const_state_e *state, bool *looping,
			tree callee)
{
  if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
    switch (DECL_FUNCTION_CODE (callee))
      {
	case BUILT_IN_RETURN:
	case BUILT_IN_UNREACHABLE:
	case BUILT_IN_ALLOCA:
	case BUILT_IN_ALLOCA_WITH_ALIGN:
	case BUILT_IN_STACK_SAVE:
	case BUILT_IN_STACK_RESTORE:
	case BUILT_IN_EH_POINTER:
	case BUILT_IN_EH_FILTER:
	case BUILT_IN_UNWIND_RESUME:
	case BUILT_IN_CXA_END_CLEANUP:
	case BUILT_IN_EH_COPY_VALUES:
	case BUILT_IN_FRAME_ADDRESS:
	case BUILT_IN_APPLY:
	case BUILT_IN_APPLY_ARGS:
	  *looping = false;
	  *state = IPA_CONST;
	  return true;
	case BUILT_IN_PREFETCH:
	  *looping = true;
	  *state = IPA_CONST;
	  return true;
	default:
	  break;
      }
  return false;
}

/* Check the parameters of a function call to CALL_EXPR to see if
   there are any references in the parameters that are not allowed for
   pure or const functions.  Also check to see if this is either an
   indirect call, a call outside the compilation unit, or has special
   attributes that may also effect the purity.  The CALL_EXPR node for
   the entire call expression.  */

static void
check_call (funct_state local, gimple call, bool ipa)
{
  int flags = gimple_call_flags (call);
  tree callee_t = gimple_call_fndecl (call);
  bool possibly_throws = stmt_could_throw_p (call);
  bool possibly_throws_externally = (possibly_throws
  				     && stmt_can_throw_external (call));

  if (possibly_throws)
    {
      unsigned int i;
      for (i = 0; i < gimple_num_ops (call); i++)
        if (gimple_op (call, i)
	    && tree_could_throw_p (gimple_op (call, i)))
	  {
	    if (possibly_throws && cfun->can_throw_non_call_exceptions)
	      {
		if (dump_file)
		  fprintf (dump_file, "    operand can throw; looping\n");
		local->looping = true;
	      }
	    if (possibly_throws_externally)
	      {
		if (dump_file)
		  fprintf (dump_file, "    operand can throw externally\n");
		local->can_throw = true;
	      }
	  }
    }

  /* The const and pure flags are set by a variety of places in the
     compiler (including here).  If someone has already set the flags
     for the callee, (such as for some of the builtins) we will use
     them, otherwise we will compute our own information.

     Const and pure functions have less clobber effects than other
     functions so we process these first.  Otherwise if it is a call
     outside the compilation unit or an indirect call we punt.  This
     leaves local calls which will be processed by following the call
     graph.  */
  if (callee_t)
    {
      enum pure_const_state_e call_state;
      bool call_looping;

      if (special_builtin_state (&call_state, &call_looping, callee_t))
	{
	  worse_state (&local->pure_const_state, &local->looping,
		       call_state, call_looping);
	  return;
	}
      /* When bad things happen to bad functions, they cannot be const
	 or pure.  */
      if (setjmp_call_p (callee_t))
	{
	  if (dump_file)
	    fprintf (dump_file, "    setjmp is not const/pure\n");
          local->looping = true;
	  local->pure_const_state = IPA_NEITHER;
	}

      if (DECL_BUILT_IN_CLASS (callee_t) == BUILT_IN_NORMAL)
	switch (DECL_FUNCTION_CODE (callee_t))
	  {
	  case BUILT_IN_LONGJMP:
	  case BUILT_IN_NONLOCAL_GOTO:
	    if (dump_file)
	      fprintf (dump_file, "    longjmp and nonlocal goto is not const/pure\n");
	    local->pure_const_state = IPA_NEITHER;
            local->looping = true;
	    break;
	  default:
	    break;
	  }
    }

  /* When not in IPA mode, we can still handle self recursion.  */
  if (!ipa && callee_t
      && recursive_call_p (current_function_decl, callee_t))
    {
      if (dump_file)
        fprintf (dump_file, "    Recursive call can loop.\n");
      local->looping = true;
    }
  /* Either callee is unknown or we are doing local analysis.
     Look to see if there are any bits available for the callee (such as by
     declaration or because it is builtin) and process solely on the basis of
     those bits. */
  else if (!ipa)
    {
      enum pure_const_state_e call_state;
      bool call_looping;
      if (possibly_throws && cfun->can_throw_non_call_exceptions)
        {
	  if (dump_file)
	    fprintf (dump_file, "    can throw; looping\n");
          local->looping = true;
	}
      if (possibly_throws_externally)
        {
	  if (dump_file)
	    {
	      fprintf (dump_file, "    can throw externally to lp %i\n",
	      	       lookup_stmt_eh_lp (call));
	      if (callee_t)
		fprintf (dump_file, "     callee:%s\n",
			 IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (callee_t)));
	    }
          local->can_throw = true;
	}
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, "    checking flags for call:");
      state_from_flags (&call_state, &call_looping, flags,
			((flags & (ECF_NORETURN | ECF_NOTHROW))
			 == (ECF_NORETURN | ECF_NOTHROW))
			|| (!flag_exceptions && (flags & ECF_NORETURN)));
      worse_state (&local->pure_const_state, &local->looping,
		   call_state, call_looping);
    }
  /* Direct functions calls are handled by IPA propagation.  */
}

/* Wrapper around check_decl for loads in local more.  */

static bool
check_load (gimple, tree op, tree, void *data)
{
  if (DECL_P (op))
    check_decl ((funct_state)data, op, false, false);
  else
    check_op ((funct_state)data, op, false);
  return false;
}

/* Wrapper around check_decl for stores in local more.  */

static bool
check_store (gimple, tree op, tree, void *data)
{
  if (DECL_P (op))
    check_decl ((funct_state)data, op, true, false);
  else
    check_op ((funct_state)data, op, true);
  return false;
}

/* Wrapper around check_decl for loads in ipa mode.  */

static bool
check_ipa_load (gimple, tree op, tree, void *data)
{
  if (DECL_P (op))
    check_decl ((funct_state)data, op, false, true);
  else
    check_op ((funct_state)data, op, false);
  return false;
}

/* Wrapper around check_decl for stores in ipa mode.  */

static bool
check_ipa_store (gimple, tree op, tree, void *data)
{
  if (DECL_P (op))
    check_decl ((funct_state)data, op, true, true);
  else
    check_op ((funct_state)data, op, true);
  return false;
}

/* Look into pointer pointed to by GSIP and figure out what interesting side
   effects it has.  */
static void
check_stmt (gimple_stmt_iterator *gsip, funct_state local, bool ipa)
{
  gimple stmt = gsi_stmt (*gsip);

  if (is_gimple_debug (stmt))
    return;

  if (dump_file)
    {
      fprintf (dump_file, "  scanning: ");
      print_gimple_stmt (dump_file, stmt, 0, 0);
    }

  if (gimple_has_volatile_ops (stmt)
      && !gimple_clobber_p (stmt))
    {
      local->pure_const_state = IPA_NEITHER;
      if (dump_file)
	fprintf (dump_file, "    Volatile stmt is not const/pure\n");
    }

  /* Look for loads and stores.  */
  walk_stmt_load_store_ops (stmt, local,
			    ipa ? check_ipa_load : check_load,
			    ipa ? check_ipa_store :  check_store);

  if (gimple_code (stmt) != GIMPLE_CALL
      && stmt_could_throw_p (stmt))
    {
      if (cfun->can_throw_non_call_exceptions)
	{
	  if (dump_file)
	    fprintf (dump_file, "    can throw; looping\n");
	  local->looping = true;
	}
      if (stmt_can_throw_external (stmt))
	{
	  if (dump_file)
	    fprintf (dump_file, "    can throw externally\n");
	  local->can_throw = true;
	}
      else
	if (dump_file)
	  fprintf (dump_file, "    can throw\n");
    }
  switch (gimple_code (stmt))
    {
    case GIMPLE_CALL:
      check_call (local, stmt, ipa);
      break;
    case GIMPLE_LABEL:
      if (DECL_NONLOCAL (gimple_label_label (stmt)))
	/* Target of long jump. */
	{
          if (dump_file)
            fprintf (dump_file, "    nonlocal label is not const/pure\n");
	  local->pure_const_state = IPA_NEITHER;
	}
      break;
    case GIMPLE_ASM:
      if (gimple_asm_clobbers_memory_p (stmt))
	{
	  if (dump_file)
	    fprintf (dump_file, "    memory asm clobber is not const/pure\n");
	  /* Abandon all hope, ye who enter here. */
	  local->pure_const_state = IPA_NEITHER;
	}
      if (gimple_asm_volatile_p (stmt))
	{
	  if (dump_file)
	    fprintf (dump_file, "    volatile is not const/pure\n");
	  /* Abandon all hope, ye who enter here. */
	  local->pure_const_state = IPA_NEITHER;
          local->looping = true;
	}
      return;
    default:
      break;
    }
}


/* This is the main routine for finding the reference patterns for
   global variables within a function FN.  */

static funct_state
analyze_function (struct cgraph_node *fn, bool ipa)
{
  tree decl = fn->decl;
  funct_state l;
  basic_block this_block;

  l = XCNEW (struct funct_state_d);
  l->pure_const_state = IPA_CONST;
  l->state_previously_known = IPA_NEITHER;
  l->looping_previously_known = true;
  l->looping = false;
  l->can_throw = false;
  state_from_flags (&l->state_previously_known, &l->looping_previously_known,
		    flags_from_decl_or_type (fn->decl),
		    fn->cannot_return_p ());

  if (fn->thunk.thunk_p || fn->alias)
    {
      /* Thunk gets propagated through, so nothing interesting happens.  */
      gcc_assert (ipa);
      return l;
    }

  if (dump_file)
    {
      fprintf (dump_file, "\n\n local analysis of %s\n ",
	       fn->name ());
    }

  push_cfun (DECL_STRUCT_FUNCTION (decl));

  FOR_EACH_BB_FN (this_block, cfun)
    {
      gimple_stmt_iterator gsi;
      struct walk_stmt_info wi;

      memset (&wi, 0, sizeof (wi));
      for (gsi = gsi_start_bb (this_block);
	   !gsi_end_p (gsi);
	   gsi_next (&gsi))
	{
	  check_stmt (&gsi, l, ipa);
	  if (l->pure_const_state == IPA_NEITHER && l->looping && l->can_throw)
	    goto end;
	}
    }

end:
  if (l->pure_const_state != IPA_NEITHER)
    {
      /* Const functions cannot have back edges (an
	 indication of possible infinite loop side
	 effect.  */
      if (mark_dfs_back_edges ())
        {
	  /* Preheaders are needed for SCEV to work.
	     Simple latches and recorded exits improve chances that loop will
	     proved to be finite in testcases such as in loop-15.c
	     and loop-24.c  */
	  loop_optimizer_init (LOOPS_HAVE_PREHEADERS
			       | LOOPS_HAVE_SIMPLE_LATCHES
			       | LOOPS_HAVE_RECORDED_EXITS);
	  if (dump_file && (dump_flags & TDF_DETAILS))
	    flow_loops_dump (dump_file, NULL, 0);
	  if (mark_irreducible_loops ())
	    {
	      if (dump_file)
	        fprintf (dump_file, "    has irreducible loops\n");
	      l->looping = true;
	    }
	  else
	    {
	      struct loop *loop;
	      scev_initialize ();
	      FOR_EACH_LOOP (loop, 0)
		if (!finite_loop_p (loop))
		  {
		    if (dump_file)
		      fprintf (dump_file, "    can not prove finiteness of "
			       "loop %i\n", loop->num);
		    l->looping =true;
		    break;
		  }
	      scev_finalize ();
	    }
          loop_optimizer_finalize ();
	}
    }

  if (dump_file && (dump_flags & TDF_DETAILS))
    fprintf (dump_file, "    checking previously known:");

  better_state (&l->pure_const_state, &l->looping,
		l->state_previously_known,
		l->looping_previously_known);
  if (TREE_NOTHROW (decl))
    l->can_throw = false;

  pop_cfun ();
  if (dump_file)
    {
      if (l->looping)
        fprintf (dump_file, "Function is locally looping.\n");
      if (l->can_throw)
        fprintf (dump_file, "Function is locally throwing.\n");
      if (l->pure_const_state == IPA_CONST)
        fprintf (dump_file, "Function is locally const.\n");
      if (l->pure_const_state == IPA_PURE)
        fprintf (dump_file, "Function is locally pure.\n");
    }
  return l;
}

/* Called when new function is inserted to callgraph late.  */
static void
add_new_function (struct cgraph_node *node, void *data ATTRIBUTE_UNUSED)
{
 if (node->get_availability () < AVAIL_INTERPOSABLE)
   return;
  /* There are some shared nodes, in particular the initializers on
     static declarations.  We do not need to scan them more than once
     since all we would be interested in are the addressof
     operations.  */
  if (node->get_availability () > AVAIL_INTERPOSABLE)
    set_function_state (node, analyze_function (node, true));
}

/* Called when new clone is inserted to callgraph late.  */

static void
duplicate_node_data (struct cgraph_node *src, struct cgraph_node *dst,
	 	     void *data ATTRIBUTE_UNUSED)
{
  if (has_function_state (src))
    {
      funct_state l = XNEW (struct funct_state_d);
      gcc_assert (!has_function_state (dst));
      memcpy (l, get_function_state (src), sizeof (*l));
      set_function_state (dst, l);
    }
}

/* Called when new clone is inserted to callgraph late.  */

static void
remove_node_data (struct cgraph_node *node, void *data ATTRIBUTE_UNUSED)
{
  if (has_function_state (node))
    {
      funct_state l = get_function_state (node);
      if (l != &varying_state)
        free (l);
      set_function_state (node, NULL);
    }
}


void
pass_ipa_pure_const::
register_hooks (void)
{
  if (init_p)
    return;

  init_p = true;

  node_removal_hook_holder =
      symtab->add_cgraph_removal_hook (&remove_node_data, NULL);
  node_duplication_hook_holder =
      symtab->add_cgraph_duplication_hook (&duplicate_node_data, NULL);
  function_insertion_hook_holder =
      symtab->add_cgraph_insertion_hook (&add_new_function, NULL);
}


/* Analyze each function in the cgraph to see if it is locally PURE or
   CONST.  */

static void
pure_const_generate_summary (void)
{
  struct cgraph_node *node;

  pass_ipa_pure_const *pass = static_cast <pass_ipa_pure_const *> (current_pass);
  pass->register_hooks ();

  /* Process all of the functions.

     We process AVAIL_INTERPOSABLE functions.  We can not use the results
     by default, but the info can be used at LTO with -fwhole-program or
     when function got cloned and the clone is AVAILABLE.  */

  FOR_EACH_DEFINED_FUNCTION (node)
    if (node->get_availability () >= AVAIL_INTERPOSABLE)
      set_function_state (node, analyze_function (node, true));
}


/* Serialize the ipa info for lto.  */

static void
pure_const_write_summary (void)
{
  struct cgraph_node *node;
  struct lto_simple_output_block *ob
    = lto_create_simple_output_block (LTO_section_ipa_pure_const);
  unsigned int count = 0;
  lto_symtab_encoder_iterator lsei;
  lto_symtab_encoder_t encoder;

  encoder = lto_get_out_decl_state ()->symtab_node_encoder;

  for (lsei = lsei_start_function_in_partition (encoder); !lsei_end_p (lsei);
       lsei_next_function_in_partition (&lsei))
    {
      node = lsei_cgraph_node (lsei);
      if (node->definition && has_function_state (node))
	count++;
    }

  streamer_write_uhwi_stream (ob->main_stream, count);

  /* Process all of the functions.  */
  for (lsei = lsei_start_function_in_partition (encoder); !lsei_end_p (lsei);
       lsei_next_function_in_partition (&lsei))
    {
      node = lsei_cgraph_node (lsei);
      if (node->definition && has_function_state (node))
	{
	  struct bitpack_d bp;
	  funct_state fs;
	  int node_ref;
	  lto_symtab_encoder_t encoder;

	  fs = get_function_state (node);

	  encoder = ob->decl_state->symtab_node_encoder;
	  node_ref = lto_symtab_encoder_encode (encoder, node);
	  streamer_write_uhwi_stream (ob->main_stream, node_ref);

	  /* Note that flags will need to be read in the opposite
	     order as we are pushing the bitflags into FLAGS.  */
	  bp = bitpack_create (ob->main_stream);
	  bp_pack_value (&bp, fs->pure_const_state, 2);
	  bp_pack_value (&bp, fs->state_previously_known, 2);
	  bp_pack_value (&bp, fs->looping_previously_known, 1);
	  bp_pack_value (&bp, fs->looping, 1);
	  bp_pack_value (&bp, fs->can_throw, 1);
	  streamer_write_bitpack (&bp);
	}
    }

  lto_destroy_simple_output_block (ob);
}


/* Deserialize the ipa info for lto.  */

static void
pure_const_read_summary (void)
{
  struct lto_file_decl_data **file_data_vec = lto_get_file_decl_data ();
  struct lto_file_decl_data *file_data;
  unsigned int j = 0;

  pass_ipa_pure_const *pass = static_cast <pass_ipa_pure_const *> (current_pass);
  pass->register_hooks ();

  while ((file_data = file_data_vec[j++]))
    {
      const char *data;
      size_t len;
      struct lto_input_block *ib
	= lto_create_simple_input_block (file_data,
					 LTO_section_ipa_pure_const,
					 &data, &len);
      if (ib)
	{
	  unsigned int i;
	  unsigned int count = streamer_read_uhwi (ib);

	  for (i = 0; i < count; i++)
	    {
	      unsigned int index;
	      struct cgraph_node *node;
	      struct bitpack_d bp;
	      funct_state fs;
	      lto_symtab_encoder_t encoder;

	      fs = XCNEW (struct funct_state_d);
	      index = streamer_read_uhwi (ib);
	      encoder = file_data->symtab_node_encoder;
	      node = dyn_cast<cgraph_node *> (lto_symtab_encoder_deref (encoder,
									index));
	      set_function_state (node, fs);

	      /* Note that the flags must be read in the opposite
		 order in which they were written (the bitflags were
		 pushed into FLAGS).  */
	      bp = streamer_read_bitpack (ib);
	      fs->pure_const_state
			= (enum pure_const_state_e) bp_unpack_value (&bp, 2);
	      fs->state_previously_known
			= (enum pure_const_state_e) bp_unpack_value (&bp, 2);
	      fs->looping_previously_known = bp_unpack_value (&bp, 1);
	      fs->looping = bp_unpack_value (&bp, 1);
	      fs->can_throw = bp_unpack_value (&bp, 1);
	      if (dump_file)
		{
		  int flags = flags_from_decl_or_type (node->decl);
		  fprintf (dump_file, "Read info for %s/%i ",
			   node->name (),
			   node->order);
		  if (flags & ECF_CONST)
		    fprintf (dump_file, " const");
		  if (flags & ECF_PURE)
		    fprintf (dump_file, " pure");
		  if (flags & ECF_NOTHROW)
		    fprintf (dump_file, " nothrow");
		  fprintf (dump_file, "\n  pure const state: %s\n",
			   pure_const_names[fs->pure_const_state]);
		  fprintf (dump_file, "  previously known state: %s\n",
			   pure_const_names[fs->looping_previously_known]);
		  if (fs->looping)
		    fprintf (dump_file,"  function is locally looping\n");
		  if (fs->looping_previously_known)
		    fprintf (dump_file,"  function is previously known looping\n");
		  if (fs->can_throw)
		    fprintf (dump_file,"  function is locally throwing\n");
		}
	    }

	  lto_destroy_simple_input_block (file_data,
					  LTO_section_ipa_pure_const,
					  ib, data, len);
	}
    }
}


static bool
ignore_edge (struct cgraph_edge *e)
{
  return (!e->can_throw_external);
}

/* Return true if NODE is self recursive function.
   Indirectly recursive functions appears as non-trivial strongly
   connected components, so we need to care about self recursion
   only.  */

static bool
self_recursive_p (struct cgraph_node *node)
{
  struct cgraph_edge *e;
  for (e = node->callees; e; e = e->next_callee)
    if (e->callee->function_symbol () == node)
      return true;
  return false;
}

/* Produce transitive closure over the callgraph and compute pure/const
   attributes.  */

static void
propagate_pure_const (void)
{
  struct cgraph_node *node;
  struct cgraph_node *w;
  struct cgraph_node **order =
    XCNEWVEC (struct cgraph_node *, symtab->cgraph_count);
  int order_pos;
  int i;
  struct ipa_dfs_info * w_info;

  order_pos = ipa_reduced_postorder (order, true, false, NULL);
  if (dump_file)
    {
      cgraph_node::dump_cgraph (dump_file);
      ipa_print_order (dump_file, "reduced", order, order_pos);
    }

  /* Propagate the local information through the call graph to produce
     the global information.  All the nodes within a cycle will have
     the same info so we collapse cycles first.  Then we can do the
     propagation in one pass from the leaves to the roots.  */
  for (i = 0; i < order_pos; i++ )
    {
      enum pure_const_state_e pure_const_state = IPA_CONST;
      bool looping = false;
      int count = 0;
      node = order[i];

      if (node->alias)
	continue;

      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, "Starting cycle\n");

      /* Find the worst state for any node in the cycle.  */
      w = node;
      while (w && pure_const_state != IPA_NEITHER)
	{
	  struct cgraph_edge *e;
	  struct cgraph_edge *ie;
	  int i;
	  struct ipa_ref *ref = NULL;

	  funct_state w_l = get_function_state (w);
	  if (dump_file && (dump_flags & TDF_DETAILS))
	    fprintf (dump_file, "  Visiting %s/%i state:%s looping %i\n",
		     w->name (),
		     w->order,
		     pure_const_names[w_l->pure_const_state],
		     w_l->looping);

	  /* First merge in function body properties.  */
	  worse_state (&pure_const_state, &looping,
		       w_l->pure_const_state, w_l->looping);
	  if (pure_const_state == IPA_NEITHER)
	    break;

	  /* For overwritable nodes we can not assume anything.  */
	  if (w->get_availability () == AVAIL_INTERPOSABLE)
	    {
	      worse_state (&pure_const_state, &looping,
			   w_l->state_previously_known,
			   w_l->looping_previously_known);
	      if (dump_file && (dump_flags & TDF_DETAILS))
		{
		  fprintf (dump_file,
			   "    Overwritable. state %s looping %i\n",
			   pure_const_names[w_l->state_previously_known],
			   w_l->looping_previously_known);
		}
	      break;
	    }

	  count++;

	  /* We consider recursive cycles as possibly infinite.
	     This might be relaxed since infinite recursion leads to stack
	     overflow.  */
	  if (count > 1)
	    looping = true;

	  /* Now walk the edges and merge in callee properties.  */
	  for (e = w->callees; e; e = e->next_callee)
	    {
	      enum availability avail;
	      struct cgraph_node *y = e->callee->function_symbol (&avail);
	      enum pure_const_state_e edge_state = IPA_CONST;
	      bool edge_looping = false;

	      if (dump_file && (dump_flags & TDF_DETAILS))
		{
		  fprintf (dump_file,
			   "    Call to %s/%i",
			   e->callee->name (),
			   e->callee->order);
		}
	      if (avail > AVAIL_INTERPOSABLE)
		{
		  funct_state y_l = get_function_state (y);
		  if (dump_file && (dump_flags & TDF_DETAILS))
		    {
		      fprintf (dump_file,
			       " state:%s looping:%i\n",
			       pure_const_names[y_l->pure_const_state],
			       y_l->looping);
		    }
		  if (y_l->pure_const_state > IPA_PURE
		      && e->cannot_lead_to_return_p ())
		    {
		      if (dump_file && (dump_flags & TDF_DETAILS))
			fprintf (dump_file,
				 "        Ignoring side effects"
				 " -> pure, looping\n");
		      edge_state = IPA_PURE;
		      edge_looping = true;
		    }
		  else
		    {
		      edge_state = y_l->pure_const_state;
		      edge_looping = y_l->looping;
		    }
		}
	      else if (special_builtin_state (&edge_state, &edge_looping,
					       y->decl))
		;
	      else
		state_from_flags (&edge_state, &edge_looping,
				  flags_from_decl_or_type (y->decl),
				  e->cannot_lead_to_return_p ());

	      /* Merge the results with what we already know.  */
	      better_state (&edge_state, &edge_looping,
			    w_l->state_previously_known,
			    w_l->looping_previously_known);
	      worse_state (&pure_const_state, &looping,
			   edge_state, edge_looping);
	      if (pure_const_state == IPA_NEITHER)
	        break;
	    }
	  if (pure_const_state == IPA_NEITHER)
	    break;

	  /* Now process the indirect call.  */
          for (ie = w->indirect_calls; ie; ie = ie->next_callee)
	    {
	      enum pure_const_state_e edge_state = IPA_CONST;
	      bool edge_looping = false;

	      if (dump_file && (dump_flags & TDF_DETAILS))
		fprintf (dump_file, "    Indirect call");
	      state_from_flags (&edge_state, &edge_looping,
			        ie->indirect_info->ecf_flags,
				ie->cannot_lead_to_return_p ());
	      /* Merge the results with what we already know.  */
	      better_state (&edge_state, &edge_looping,
			    w_l->state_previously_known,
			    w_l->looping_previously_known);
	      worse_state (&pure_const_state, &looping,
			   edge_state, edge_looping);
	      if (pure_const_state == IPA_NEITHER)
	        break;
	    }
	  if (pure_const_state == IPA_NEITHER)
	    break;

	  /* And finally all loads and stores.  */
	  for (i = 0; w->iterate_reference (i, ref); i++)
	    {
	      enum pure_const_state_e ref_state = IPA_CONST;
	      bool ref_looping = false;
	      switch (ref->use)
		{
		case IPA_REF_LOAD:
		  /* readonly reads are safe.  */
		  if (TREE_READONLY (ref->referred->decl))
		    break;
		  if (dump_file && (dump_flags & TDF_DETAILS))
		    fprintf (dump_file, "    nonreadonly global var read\n");
		  ref_state = IPA_PURE;
		  break;
		case IPA_REF_STORE:
		  if (ref->cannot_lead_to_return ())
		    break;
		  ref_state = IPA_NEITHER;
		  if (dump_file && (dump_flags & TDF_DETAILS))
		    fprintf (dump_file, "    global var write\n");
		  break;
		case IPA_REF_ADDR:
		  break;
		default:
		  gcc_unreachable ();
		}
	      better_state (&ref_state, &ref_looping,
			    w_l->state_previously_known,
			    w_l->looping_previously_known);
	      worse_state (&pure_const_state, &looping,
			   ref_state, ref_looping);
	      if (pure_const_state == IPA_NEITHER)
		break;
	    }
	  w_info = (struct ipa_dfs_info *) w->aux;
	  w = w_info->next_cycle;
	}
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, "Result %s looping %i\n",
		 pure_const_names [pure_const_state],
		 looping);

      /* Copy back the region's pure_const_state which is shared by
	 all nodes in the region.  */
      w = node;
      while (w)
	{
	  funct_state w_l = get_function_state (w);
	  enum pure_const_state_e this_state = pure_const_state;
	  bool this_looping = looping;

	  if (w_l->state_previously_known != IPA_NEITHER
	      && this_state > w_l->state_previously_known)
	    {
              this_state = w_l->state_previously_known;
	      this_looping |= w_l->looping_previously_known;
	    }
	  if (!this_looping && self_recursive_p (w))
	    this_looping = true;
	  if (!w_l->looping_previously_known)
	    this_looping = false;

	  /* All nodes within a cycle share the same info.  */
	  w_l->pure_const_state = this_state;
	  w_l->looping = this_looping;

	  /* Inline clones share declaration with their offline copies;
	     do not modify their declarations since the offline copy may
	     be different.  */
	  if (!w->global.inlined_to)
	    switch (this_state)
	      {
	      case IPA_CONST:
		if (!TREE_READONLY (w->decl))
		  {
		    warn_function_const (w->decl, !this_looping);
		    if (dump_file)
		      fprintf (dump_file, "Function found to be %sconst: %s\n",
			       this_looping ? "looping " : "",
			       w->name ());
		  }
		w->set_const_flag (true, this_looping);
		break;

	      case IPA_PURE:
		if (!DECL_PURE_P (w->decl))
		  {
		    warn_function_pure (w->decl, !this_looping);
		    if (dump_file)
		      fprintf (dump_file, "Function found to be %spure: %s\n",
			       this_looping ? "looping " : "",
			       w->name ());
		  }
		w->set_pure_flag (true, this_looping);
		break;

	      default:
		break;
	      }
	  w_info = (struct ipa_dfs_info *) w->aux;
	  w = w_info->next_cycle;
	}
    }

  ipa_free_postorder_info ();
  free (order);
}

/* Produce transitive closure over the callgraph and compute nothrow
   attributes.  */

static void
propagate_nothrow (void)
{
  struct cgraph_node *node;
  struct cgraph_node *w;
  struct cgraph_node **order =
    XCNEWVEC (struct cgraph_node *, symtab->cgraph_count);
  int order_pos;
  int i;
  struct ipa_dfs_info * w_info;

  order_pos = ipa_reduced_postorder (order, true, false, ignore_edge);
  if (dump_file)
    {
      cgraph_node::dump_cgraph (dump_file);
      ipa_print_order (dump_file, "reduced for nothrow", order, order_pos);
    }

  /* Propagate the local information through the call graph to produce
     the global information.  All the nodes within a cycle will have
     the same info so we collapse cycles first.  Then we can do the
     propagation in one pass from the leaves to the roots.  */
  for (i = 0; i < order_pos; i++ )
    {
      bool can_throw = false;
      node = order[i];

      if (node->alias)
	continue;

      /* Find the worst state for any node in the cycle.  */
      w = node;
      while (w)
	{
	  struct cgraph_edge *e, *ie;
	  funct_state w_l = get_function_state (w);

	  if (w_l->can_throw
	      || w->get_availability () == AVAIL_INTERPOSABLE)
	    can_throw = true;

	  if (can_throw)
	    break;

	  for (e = w->callees; e; e = e->next_callee)
	    {
	      enum availability avail;
	      struct cgraph_node *y = e->callee->function_symbol (&avail);

	      if (avail > AVAIL_INTERPOSABLE)
		{
		  funct_state y_l = get_function_state (y);

		  if (can_throw)
		    break;
		  if (y_l->can_throw && !TREE_NOTHROW (w->decl)
		      && e->can_throw_external)
		    can_throw = true;
		}
	      else if (e->can_throw_external && !TREE_NOTHROW (y->decl))
	        can_throw = true;
	    }
          for (ie = node->indirect_calls; ie; ie = ie->next_callee)
	    if (ie->can_throw_external)
	      {
		can_throw = true;
		break;
	      }
	  w_info = (struct ipa_dfs_info *) w->aux;
	  w = w_info->next_cycle;
	}

      /* Copy back the region's pure_const_state which is shared by
	 all nodes in the region.  */
      w = node;
      while (w)
	{
	  funct_state w_l = get_function_state (w);
	  if (!can_throw && !TREE_NOTHROW (w->decl))
	    {
	      /* Inline clones share declaration with their offline copies;
		 do not modify their declarations since the offline copy may
		 be different.  */
	      if (!w->global.inlined_to)
		{
		  w->set_nothrow_flag (true);
		  if (dump_file)
		    fprintf (dump_file, "Function found to be nothrow: %s\n",
			     w->name ());
		}
	    }
	  else if (can_throw && !TREE_NOTHROW (w->decl))
	    w_l->can_throw = true;
	  w_info = (struct ipa_dfs_info *) w->aux;
	  w = w_info->next_cycle;
	}
    }

  ipa_free_postorder_info ();
  free (order);
}


/* Produce the global information by preforming a transitive closure
   on the local information that was produced by generate_summary.  */

unsigned int
pass_ipa_pure_const::
execute (function *)
{
  struct cgraph_node *node;

  symtab->remove_cgraph_insertion_hook (function_insertion_hook_holder);
  symtab->remove_cgraph_duplication_hook (node_duplication_hook_holder);
  symtab->remove_cgraph_removal_hook (node_removal_hook_holder);

  /* Nothrow makes more function to not lead to return and improve
     later analysis.  */
  propagate_nothrow ();
  propagate_pure_const ();

  /* Cleanup. */
  FOR_EACH_FUNCTION (node)
    if (has_function_state (node))
      free (get_function_state (node));
  funct_state_vec.release ();
  return 0;
}

static bool
gate_pure_const (void)
{
  return (flag_ipa_pure_const
	  /* Don't bother doing anything if the program has errors.  */
	  && !seen_error ());
}

pass_ipa_pure_const::pass_ipa_pure_const(gcc::context *ctxt)
    : ipa_opt_pass_d(pass_data_ipa_pure_const, ctxt,
		     pure_const_generate_summary, /* generate_summary */
		     pure_const_write_summary, /* write_summary */
		     pure_const_read_summary, /* 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 */
  init_p(false),
  function_insertion_hook_holder(NULL),
  node_duplication_hook_holder(NULL),
  node_removal_hook_holder(NULL)
{
}

ipa_opt_pass_d *
make_pass_ipa_pure_const (gcc::context *ctxt)
{
  return new pass_ipa_pure_const (ctxt);
}

/* Return true if function should be skipped for local pure const analysis.  */

static bool
skip_function_for_local_pure_const (struct cgraph_node *node)
{
  /* Because we do not schedule pass_fixup_cfg over whole program after early optimizations
     we must not promote functions that are called by already processed functions.  */

  if (function_called_by_processed_nodes_p ())
    {
      if (dump_file)
        fprintf (dump_file, "Function called in recursive cycle; ignoring\n");
      return true;
    }
  if (node->get_availability () <= AVAIL_INTERPOSABLE)
    {
      if (dump_file)
        fprintf (dump_file, "Function is not available or overwritable; not analyzing.\n");
      return true;
    }
  return false;
}

/* Simple local pass for pure const discovery reusing the analysis from
   ipa_pure_const.   This pass is effective when executed together with
   other optimization passes in early optimization pass queue.  */

namespace {

const pass_data pass_data_local_pure_const =
{
  GIMPLE_PASS, /* type */
  "local-pure-const", /* name */
  OPTGROUP_NONE, /* optinfo_flags */
  TV_IPA_PURE_CONST, /* tv_id */
  0, /* properties_required */
  0, /* properties_provided */
  0, /* properties_destroyed */
  0, /* todo_flags_start */
  0, /* todo_flags_finish */
};

class pass_local_pure_const : public gimple_opt_pass
{
public:
  pass_local_pure_const (gcc::context *ctxt)
    : gimple_opt_pass (pass_data_local_pure_const, ctxt)
  {}

  /* opt_pass methods: */
  opt_pass * clone () { return new pass_local_pure_const (m_ctxt); }
  virtual bool gate (function *) { return gate_pure_const (); }
  virtual unsigned int execute (function *);

}; // class pass_local_pure_const

unsigned int
pass_local_pure_const::execute (function *fun)
{
  bool changed = false;
  funct_state l;
  bool skip;
  struct cgraph_node *node;

  node = cgraph_node::get (current_function_decl);
  skip = skip_function_for_local_pure_const (node);
  if (!warn_suggest_attribute_const
      && !warn_suggest_attribute_pure
      && skip)
    return 0;

  l = analyze_function (node, false);

  /* Do NORETURN discovery.  */
  if (!skip && !TREE_THIS_VOLATILE (current_function_decl)
      && EDGE_COUNT (EXIT_BLOCK_PTR_FOR_FN (fun)->preds) == 0)
    {
      warn_function_noreturn (fun->decl);
      if (dump_file)
	fprintf (dump_file, "Function found to be noreturn: %s\n",
		 current_function_name ());

      /* Update declaration and reduce profile to executed once.  */
      TREE_THIS_VOLATILE (current_function_decl) = 1;
      if (node->frequency > NODE_FREQUENCY_EXECUTED_ONCE)
	node->frequency = NODE_FREQUENCY_EXECUTED_ONCE;

      changed = true;
    }

  switch (l->pure_const_state)
    {
    case IPA_CONST:
      if (!TREE_READONLY (current_function_decl))
	{
	  warn_function_const (current_function_decl, !l->looping);
	  if (!skip)
	    {
	      node->set_const_flag (true, l->looping);
	      changed = true;
	    }
	  if (dump_file)
	    fprintf (dump_file, "Function found to be %sconst: %s\n",
		     l->looping ? "looping " : "",
		     current_function_name ());
	}
      else if (DECL_LOOPING_CONST_OR_PURE_P (current_function_decl)
	       && !l->looping)
	{
	  if (!skip)
	    {
	      node->set_const_flag (true, false);
	      changed = true;
	    }
	  if (dump_file)
	    fprintf (dump_file, "Function found to be non-looping: %s\n",
		     current_function_name ());
	}
      break;

    case IPA_PURE:
      if (!DECL_PURE_P (current_function_decl))
	{
	  if (!skip)
	    {
	      node->set_pure_flag (true, l->looping);
	      changed = true;
	    }
	  warn_function_pure (current_function_decl, !l->looping);
	  if (dump_file)
	    fprintf (dump_file, "Function found to be %spure: %s\n",
		     l->looping ? "looping " : "",
		     current_function_name ());
	}
      else if (DECL_LOOPING_CONST_OR_PURE_P (current_function_decl)
	       && !l->looping)
	{
	  if (!skip)
	    {
	      node->set_pure_flag (true, false);
	      changed = true;
	    }
	  if (dump_file)
	    fprintf (dump_file, "Function found to be non-looping: %s\n",
		     current_function_name ());
	}
      break;

    default:
      break;
    }
  if (!l->can_throw && !TREE_NOTHROW (current_function_decl))
    {
      node->set_nothrow_flag (true);
      changed = true;
      if (dump_file)
	fprintf (dump_file, "Function found to be nothrow: %s\n",
		 current_function_name ());
    }
  free (l);
  if (changed)
    return execute_fixup_cfg ();
  else
    return 0;
}

} // anon namespace

gimple_opt_pass *
make_pass_local_pure_const (gcc::context *ctxt)
{
  return new pass_local_pure_const (ctxt);
}

/* Emit noreturn warnings.  */

namespace {

const pass_data pass_data_warn_function_noreturn =
{
  GIMPLE_PASS, /* type */
  "*warn_function_noreturn", /* name */
  OPTGROUP_NONE, /* optinfo_flags */
  TV_NONE, /* tv_id */
  PROP_cfg, /* properties_required */
  0, /* properties_provided */
  0, /* properties_destroyed */
  0, /* todo_flags_start */
  0, /* todo_flags_finish */
};

class pass_warn_function_noreturn : public gimple_opt_pass
{
public:
  pass_warn_function_noreturn (gcc::context *ctxt)
    : gimple_opt_pass (pass_data_warn_function_noreturn, ctxt)
  {}

  /* opt_pass methods: */
  virtual bool gate (function *) { return warn_suggest_attribute_noreturn; }
  virtual unsigned int execute (function *fun)
    {
      if (!TREE_THIS_VOLATILE (current_function_decl)
	  && EDGE_COUNT (EXIT_BLOCK_PTR_FOR_FN (fun)->preds) == 0)
	warn_function_noreturn (current_function_decl);
      return 0;
    }

}; // class pass_warn_function_noreturn

} // anon namespace

gimple_opt_pass *
make_pass_warn_function_noreturn (gcc::context *ctxt)
{
  return new pass_warn_function_noreturn (ctxt);
}