aboutsummaryrefslogtreecommitdiff
path: root/gdb/minsyms.c
blob: 1d77882285881733a0ccd5c5758e8da2c7ab0026 (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
/* GDB routines for manipulating the minimal symbol tables.
   Copyright (C) 1992-2023 Free Software Foundation, Inc.
   Contributed by Cygnus Support, using pieces from other GDB modules.

   This file is part of GDB.

   This program 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 of the License, or
   (at your option) any later version.

   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */


/* This file contains support routines for creating, manipulating, and
   destroying minimal symbol tables.

   Minimal symbol tables are used to hold some very basic information about
   all defined global symbols (text, data, bss, abs, etc).  The only two
   required pieces of information are the symbol's name and the address
   associated with that symbol.

   In many cases, even if a file was compiled with no special options for
   debugging at all, as long as was not stripped it will contain sufficient
   information to build useful minimal symbol tables using this structure.

   Even when a file contains enough debugging information to build a full
   symbol table, these minimal symbols are still useful for quickly mapping
   between names and addresses, and vice versa.  They are also sometimes used
   to figure out what full symbol table entries need to be read in.  */


#include "defs.h"
#include <ctype.h>
#include "symtab.h"
#include "bfd.h"
#include "filenames.h"
#include "symfile.h"
#include "objfiles.h"
#include "demangle.h"
#include "value.h"
#include "cp-abi.h"
#include "target.h"
#include "cp-support.h"
#include "language.h"
#include "cli/cli-utils.h"
#include "gdbsupport/symbol.h"
#include <algorithm>
#include "gdbsupport/gdb-safe-ctype.h"
#include "gdbsupport/parallel-for.h"
#include "inferior.h"

#if CXX_STD_THREAD
#include <mutex>
#endif

/* Return true if MINSYM is a cold clone symbol.
   Recognize f.i. these symbols (mangled/demangled):
   - _ZL3foov.cold
     foo() [clone .cold]
   - _ZL9do_rpo_vnP8functionP8edge_defP11bitmap_headbb.cold.138
     do_rpo_vn(function*, edge_def*, bitmap_head*, bool, bool)	\
       [clone .cold.138].  */

static bool
msymbol_is_cold_clone (minimal_symbol *minsym)
{
  const char *name = minsym->natural_name ();
  size_t name_len = strlen (name);
  if (name_len < 1)
    return false;

  const char *last = &name[name_len - 1];
  if (*last != ']')
    return false;

  const char *suffix = " [clone .cold";
  size_t suffix_len = strlen (suffix);
  const char *found = strstr (name, suffix);
  if (found == nullptr)
    return false;

  const char *start = &found[suffix_len];
  if (*start == ']')
    return true;

  if (*start != '.')
    return false;

  const char *p;
  for (p = start + 1; p <= last; ++p)
    {
      if (*p >= '0' && *p <= '9')
	continue;
      break;
    }

  if (p == last)
    return true;

  return false;
}

/* See minsyms.h.  */

bool
msymbol_is_function (struct objfile *objfile, minimal_symbol *minsym,
		     CORE_ADDR *func_address_p)
{
  CORE_ADDR msym_addr = minsym->value_address (objfile);

  switch (minsym->type ())
    {
    case mst_slot_got_plt:
    case mst_data:
    case mst_bss:
    case mst_abs:
    case mst_file_data:
    case mst_file_bss:
    case mst_data_gnu_ifunc:
      {
	struct gdbarch *gdbarch = objfile->arch ();
	CORE_ADDR pc = gdbarch_convert_from_func_ptr_addr
	  (gdbarch, msym_addr, current_inferior ()->top_target ());
	if (pc != msym_addr)
	  {
	    if (func_address_p != NULL)
	      *func_address_p = pc;
	    return true;
	  }
	return false;
      }
    case mst_file_text:
      /* Ignore function symbol that is not a function entry.  */
      if (msymbol_is_cold_clone (minsym))
	return false;
      /* fallthru */
    default:
      if (func_address_p != NULL)
	*func_address_p = msym_addr;
      return true;
    }
}

/* Accumulate the minimal symbols for each objfile in bunches of BUNCH_SIZE.
   At the end, copy them all into one newly allocated array.  */

#define BUNCH_SIZE 127

struct msym_bunch
  {
    struct msym_bunch *next;
    struct minimal_symbol contents[BUNCH_SIZE];
  };

/* See minsyms.h.  */

unsigned int
msymbol_hash_iw (const char *string)
{
  unsigned int hash = 0;

  while (*string && *string != '(')
    {
      string = skip_spaces (string);
      if (*string && *string != '(')
	{
	  hash = SYMBOL_HASH_NEXT (hash, *string);
	  ++string;
	}
    }
  return hash;
}

/* See minsyms.h.  */

unsigned int
msymbol_hash (const char *string)
{
  unsigned int hash = 0;

  for (; *string; ++string)
    hash = SYMBOL_HASH_NEXT (hash, *string);
  return hash;
}

/* Add the minimal symbol SYM to an objfile's minsym hash table, TABLE.  */
static void
add_minsym_to_hash_table (struct minimal_symbol *sym,
			  struct minimal_symbol **table,
			  unsigned int hash_value)
{
  if (sym->hash_next == NULL)
    {
      unsigned int hash = hash_value % MINIMAL_SYMBOL_HASH_SIZE;

      sym->hash_next = table[hash];
      table[hash] = sym;
    }
}

/* Add the minimal symbol SYM to an objfile's minsym demangled hash table,
   TABLE.  */
static void
add_minsym_to_demangled_hash_table (struct minimal_symbol *sym,
				    struct objfile *objfile,
				    unsigned int hash_value)
{
  if (sym->demangled_hash_next == NULL)
    {
      objfile->per_bfd->demangled_hash_languages.set (sym->language ());

      struct minimal_symbol **table
	= objfile->per_bfd->msymbol_demangled_hash;
      unsigned int hash_index = hash_value % MINIMAL_SYMBOL_HASH_SIZE;
      sym->demangled_hash_next = table[hash_index];
      table[hash_index] = sym;
    }
}

/* Worker object for lookup_minimal_symbol.  Stores temporary results
   while walking the symbol tables.  */

struct found_minimal_symbols
{
  /* External symbols are best.  */
  bound_minimal_symbol external_symbol;

  /* File-local symbols are next best.  */
  bound_minimal_symbol file_symbol;

  /* Symbols for shared library trampolines are next best.  */
  bound_minimal_symbol trampoline_symbol;

  /* Called when a symbol name matches.  Check if the minsym is a
     better type than what we had already found, and record it in one
     of the members fields if so.  Returns true if we collected the
     real symbol, in which case we can stop searching.  */
  bool maybe_collect (const char *sfile, objfile *objf,
		      minimal_symbol *msymbol);
};

/* See declaration above.  */

bool
found_minimal_symbols::maybe_collect (const char *sfile,
				      struct objfile *objfile,
				      minimal_symbol *msymbol)
{
  switch (msymbol->type ())
    {
    case mst_file_text:
    case mst_file_data:
    case mst_file_bss:
      if (sfile == NULL
	  || filename_cmp (msymbol->filename, sfile) == 0)
	{
	  file_symbol.minsym = msymbol;
	  file_symbol.objfile = objfile;
	}
      break;

    case mst_solib_trampoline:

      /* If a trampoline symbol is found, we prefer to keep
	 looking for the *real* symbol.  If the actual symbol
	 is not found, then we'll use the trampoline
	 entry.  */
      if (trampoline_symbol.minsym == NULL)
	{
	  trampoline_symbol.minsym = msymbol;
	  trampoline_symbol.objfile = objfile;
	}
      break;

    case mst_unknown:
    default:
      external_symbol.minsym = msymbol;
      external_symbol.objfile = objfile;
      /* We have the real symbol.  No use looking further.  */
      return true;
    }

  /* Keep looking.  */
  return false;
}

/* Walk the mangled name hash table, and pass each symbol whose name
   matches LOOKUP_NAME according to NAMECMP to FOUND.  */

static void
lookup_minimal_symbol_mangled (const char *lookup_name,
			       const char *sfile,
			       struct objfile *objfile,
			       struct minimal_symbol **table,
			       unsigned int hash,
			       int (*namecmp) (const char *, const char *),
			       found_minimal_symbols &found)
{
  for (minimal_symbol *msymbol = table[hash];
       msymbol != NULL;
       msymbol = msymbol->hash_next)
    {
      const char *symbol_name = msymbol->linkage_name ();

      if (namecmp (symbol_name, lookup_name) == 0
	  && found.maybe_collect (sfile, objfile, msymbol))
	return;
    }
}

/* Walk the demangled name hash table, and pass each symbol whose name
   matches LOOKUP_NAME according to MATCHER to FOUND.  */

static void
lookup_minimal_symbol_demangled (const lookup_name_info &lookup_name,
				 const char *sfile,
				 struct objfile *objfile,
				 struct minimal_symbol **table,
				 unsigned int hash,
				 symbol_name_matcher_ftype *matcher,
				 found_minimal_symbols &found)
{
  for (minimal_symbol *msymbol = table[hash];
       msymbol != NULL;
       msymbol = msymbol->demangled_hash_next)
    {
      const char *symbol_name = msymbol->search_name ();

      if (matcher (symbol_name, lookup_name, NULL)
	  && found.maybe_collect (sfile, objfile, msymbol))
	return;
    }
}

/* Look through all the current minimal symbol tables and find the
   first minimal symbol that matches NAME.  If OBJF is non-NULL, limit
   the search to that objfile.  If SFILE is non-NULL, the only file-scope
   symbols considered will be from that source file (global symbols are
   still preferred).  Returns a pointer to the minimal symbol that
   matches, or NULL if no match is found.

   Note:  One instance where there may be duplicate minimal symbols with
   the same name is when the symbol tables for a shared library and the
   symbol tables for an executable contain global symbols with the same
   names (the dynamic linker deals with the duplication).

   It's also possible to have minimal symbols with different mangled
   names, but identical demangled names.  For example, the GNU C++ v3
   ABI requires the generation of two (or perhaps three) copies of
   constructor functions --- "in-charge", "not-in-charge", and
   "allocate" copies; destructors may be duplicated as well.
   Obviously, there must be distinct mangled names for each of these,
   but the demangled names are all the same: S::S or S::~S.  */

struct bound_minimal_symbol
lookup_minimal_symbol (const char *name, const char *sfile,
		       struct objfile *objf)
{
  found_minimal_symbols found;

  unsigned int mangled_hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;

  auto *mangled_cmp
    = (case_sensitivity == case_sensitive_on
       ? strcmp
       : strcasecmp);

  if (sfile != NULL)
    sfile = lbasename (sfile);

  lookup_name_info lookup_name (name, symbol_name_match_type::FULL);

  for (objfile *objfile : current_program_space->objfiles ())
    {
      if (found.external_symbol.minsym != NULL)
	break;

      if (objf == NULL || objf == objfile
	  || objf == objfile->separate_debug_objfile_backlink)
	{
	  symbol_lookup_debug_printf ("lookup_minimal_symbol (%s, %s, %s)",
				      name, sfile != NULL ? sfile : "NULL",
				      objfile_debug_name (objfile));

	  /* Do two passes: the first over the ordinary hash table,
	     and the second over the demangled hash table.  */
	  lookup_minimal_symbol_mangled (name, sfile, objfile,
					 objfile->per_bfd->msymbol_hash,
					 mangled_hash, mangled_cmp, found);

	  /* If not found, try the demangled hash table.  */
	  if (found.external_symbol.minsym == NULL)
	    {
	      /* Once for each language in the demangled hash names
		 table (usually just zero or one languages).  */
	      for (unsigned iter = 0; iter < nr_languages; ++iter)
		{
		  if (!objfile->per_bfd->demangled_hash_languages.test (iter))
		    continue;
		  enum language lang = (enum language) iter;

		  unsigned int hash
		    = (lookup_name.search_name_hash (lang)
		       % MINIMAL_SYMBOL_HASH_SIZE);

		  symbol_name_matcher_ftype *match
		    = language_def (lang)->get_symbol_name_matcher
							(lookup_name);
		  struct minimal_symbol **msymbol_demangled_hash
		    = objfile->per_bfd->msymbol_demangled_hash;

		  lookup_minimal_symbol_demangled (lookup_name, sfile, objfile,
						   msymbol_demangled_hash,
						   hash, match, found);

		  if (found.external_symbol.minsym != NULL)
		    break;
		}
	    }
	}
    }

  /* External symbols are best.  */
  if (found.external_symbol.minsym != NULL)
    {
      if (symbol_lookup_debug)
	{
	  minimal_symbol *minsym = found.external_symbol.minsym;

	  symbol_lookup_debug_printf
	    ("lookup_minimal_symbol (...) = %s (external)",
	     host_address_to_string (minsym));
	}
      return found.external_symbol;
    }

  /* File-local symbols are next best.  */
  if (found.file_symbol.minsym != NULL)
    {
      if (symbol_lookup_debug)
	{
	  minimal_symbol *minsym = found.file_symbol.minsym;

	  symbol_lookup_debug_printf
	    ("lookup_minimal_symbol (...) = %s (file-local)",
	     host_address_to_string (minsym));
	}
      return found.file_symbol;
    }

  /* Symbols for shared library trampolines are next best.  */
  if (found.trampoline_symbol.minsym != NULL)
    {
      if (symbol_lookup_debug)
	{
	  minimal_symbol *minsym = found.trampoline_symbol.minsym;

	  symbol_lookup_debug_printf
	    ("lookup_minimal_symbol (...) = %s (trampoline)",
	     host_address_to_string (minsym));
	}

      return found.trampoline_symbol;
    }

  /* Not found.  */
  symbol_lookup_debug_printf ("lookup_minimal_symbol (...) = NULL");
  return {};
}

/* See minsyms.h.  */

struct bound_minimal_symbol
lookup_bound_minimal_symbol (const char *name)
{
  return lookup_minimal_symbol (name, NULL, NULL);
}

/* See gdbsupport/symbol.h.  */

int
find_minimal_symbol_address (const char *name, CORE_ADDR *addr,
			     struct objfile *objfile)
{
  struct bound_minimal_symbol sym
    = lookup_minimal_symbol (name, NULL, objfile);

  if (sym.minsym != NULL)
    *addr = sym.value_address ();

  return sym.minsym == NULL;
}

/* Get the lookup name form best suitable for linkage name
   matching.  */

static const char *
linkage_name_str (const lookup_name_info &lookup_name)
{
  /* Unlike most languages (including C++), Ada uses the
     encoded/linkage name as the search name recorded in symbols.  So
     if debugging in Ada mode, prefer the Ada-encoded name.  This also
     makes Ada's verbatim match syntax ("<...>") work, because
     "lookup_name.name()" includes the "<>"s, while
     "lookup_name.ada().lookup_name()" is the encoded name with "<>"s
     stripped.  */
  if (current_language->la_language == language_ada)
    return lookup_name.ada ().lookup_name ().c_str ();

  return lookup_name.c_str ();
}

/* See minsyms.h.  */

void
iterate_over_minimal_symbols
    (struct objfile *objf, const lookup_name_info &lookup_name,
     gdb::function_view<bool (struct minimal_symbol *)> callback)
{
  /* The first pass is over the ordinary hash table.  */
    {
      const char *name = linkage_name_str (lookup_name);
      unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;
      auto *mangled_cmp
	= (case_sensitivity == case_sensitive_on
	   ? strcmp
	   : strcasecmp);

      for (minimal_symbol *iter = objf->per_bfd->msymbol_hash[hash];
	   iter != NULL;
	   iter = iter->hash_next)
	{
	  if (mangled_cmp (iter->linkage_name (), name) == 0)
	    if (callback (iter))
	      return;
	}
    }

  /* The second pass is over the demangled table.  Once for each
     language in the demangled hash names table (usually just zero or
     one).  */
  for (unsigned liter = 0; liter < nr_languages; ++liter)
    {
      if (!objf->per_bfd->demangled_hash_languages.test (liter))
	continue;

      enum language lang = (enum language) liter;
      const language_defn *lang_def = language_def (lang);
      symbol_name_matcher_ftype *name_match
	= lang_def->get_symbol_name_matcher (lookup_name);

      unsigned int hash
	= lookup_name.search_name_hash (lang) % MINIMAL_SYMBOL_HASH_SIZE;
      for (minimal_symbol *iter = objf->per_bfd->msymbol_demangled_hash[hash];
	   iter != NULL;
	   iter = iter->demangled_hash_next)
	if (name_match (iter->search_name (), lookup_name, NULL))
	  if (callback (iter))
	    return;
    }
}

/* See minsyms.h.  */

bound_minimal_symbol
lookup_minimal_symbol_linkage (const char *name, struct objfile *objf)
{
  unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;

  for (objfile *objfile : objf->separate_debug_objfiles ())
    {
      for (minimal_symbol *msymbol = objfile->per_bfd->msymbol_hash[hash];
	   msymbol != NULL;
	   msymbol = msymbol->hash_next)
	{
	  if (strcmp (msymbol->linkage_name (), name) == 0
	      && (msymbol->type () == mst_data
		  || msymbol->type () == mst_bss))
	    return {msymbol, objfile};
	}
    }

  return {};
}

/* See minsyms.h.  */

struct bound_minimal_symbol
lookup_minimal_symbol_linkage (const char *name, bool only_main)
{
  for (objfile *objfile : current_program_space->objfiles ())
    {
      if (objfile->separate_debug_objfile_backlink != nullptr)
	continue;

      if (only_main && (objfile->flags & OBJF_MAINLINE) == 0)
	continue;

      bound_minimal_symbol minsym = lookup_minimal_symbol_linkage (name,
								   objfile);
      if (minsym.minsym != nullptr)
	return minsym;
    }

  return {};
}

/* See minsyms.h.  */

struct bound_minimal_symbol
lookup_minimal_symbol_text (const char *name, struct objfile *objf)
{
  struct minimal_symbol *msymbol;
  struct bound_minimal_symbol found_symbol;
  struct bound_minimal_symbol found_file_symbol;

  unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;

  for (objfile *objfile : current_program_space->objfiles ())
    {
      if (found_symbol.minsym != NULL)
	break;

      if (objf == NULL || objf == objfile
	  || objf == objfile->separate_debug_objfile_backlink)
	{
	  for (msymbol = objfile->per_bfd->msymbol_hash[hash];
	       msymbol != NULL && found_symbol.minsym == NULL;
	       msymbol = msymbol->hash_next)
	    {
	      if (strcmp (msymbol->linkage_name (), name) == 0 &&
		  (msymbol->type () == mst_text
		   || msymbol->type () == mst_text_gnu_ifunc
		   || msymbol->type () == mst_file_text))
		{
		  switch (msymbol->type ())
		    {
		    case mst_file_text:
		      found_file_symbol.minsym = msymbol;
		      found_file_symbol.objfile = objfile;
		      break;
		    default:
		      found_symbol.minsym = msymbol;
		      found_symbol.objfile = objfile;
		      break;
		    }
		}
	    }
	}
    }
  /* External symbols are best.  */
  if (found_symbol.minsym)
    return found_symbol;

  /* File-local symbols are next best.  */
  return found_file_symbol;
}

/* See minsyms.h.  */

struct minimal_symbol *
lookup_minimal_symbol_by_pc_name (CORE_ADDR pc, const char *name,
				  struct objfile *objf)
{
  struct minimal_symbol *msymbol;

  unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;

  for (objfile *objfile : current_program_space->objfiles ())
    {
      if (objf == NULL || objf == objfile
	  || objf == objfile->separate_debug_objfile_backlink)
	{
	  for (msymbol = objfile->per_bfd->msymbol_hash[hash];
	       msymbol != NULL;
	       msymbol = msymbol->hash_next)
	    {
	      if (msymbol->value_address (objfile) == pc
		  && strcmp (msymbol->linkage_name (), name) == 0)
		return msymbol;
	    }
	}
    }

  return NULL;
}

/* A helper function that makes *PC section-relative.  This searches
   the sections of OBJFILE and if *PC is in a section, it subtracts
   the section offset, stores the result into UNREL_ADDR, and returns
   true.  Otherwise it returns false.  */

static int
frob_address (struct objfile *objfile, CORE_ADDR pc,
	      unrelocated_addr *unrel_addr)
{
  for (obj_section *iter : objfile->sections ())
    {
      if (pc >= iter->addr () && pc < iter->endaddr ())
	{
	  *unrel_addr = unrelocated_addr (pc - iter->offset ());
	  return 1;
	}
    }

  return 0;
}

/* Helper for lookup_minimal_symbol_by_pc_section.  Convert a
   lookup_msym_prefer to a minimal_symbol_type.  */

static minimal_symbol_type
msym_prefer_to_msym_type (lookup_msym_prefer prefer)
{
  switch (prefer)
    {
    case lookup_msym_prefer::TEXT:
      return mst_text;
    case lookup_msym_prefer::TRAMPOLINE:
      return mst_solib_trampoline;
    case lookup_msym_prefer::GNU_IFUNC:
      return mst_text_gnu_ifunc;
    }

  /* Assert here instead of in a default switch case above so that
     -Wswitch warns if a new enumerator is added.  */
  gdb_assert_not_reached ("unhandled lookup_msym_prefer");
}

/* See minsyms.h.

   Note that we need to look through ALL the minimal symbol tables
   before deciding on the symbol that comes closest to the specified PC.
   This is because objfiles can overlap, for example objfile A has .text
   at 0x100 and .data at 0x40000 and objfile B has .text at 0x234 and
   .data at 0x40048.  */

bound_minimal_symbol
lookup_minimal_symbol_by_pc_section (CORE_ADDR pc_in, struct obj_section *section,
				     lookup_msym_prefer prefer,
				     bound_minimal_symbol *previous)
{
  int lo;
  int hi;
  int newobj;
  struct minimal_symbol *msymbol;
  struct minimal_symbol *best_symbol = NULL;
  struct objfile *best_objfile = NULL;
  struct bound_minimal_symbol result;

  if (previous != nullptr)
    {
      previous->minsym = nullptr;
      previous->objfile = nullptr;
    }

  if (section == NULL)
    {
      section = find_pc_section (pc_in);
      if (section == NULL)
	return {};
    }

  minimal_symbol_type want_type = msym_prefer_to_msym_type (prefer);

  /* We can not require the symbol found to be in section, because
     e.g. IRIX 6.5 mdebug relies on this code returning an absolute
     symbol - but find_pc_section won't return an absolute section and
     hence the code below would skip over absolute symbols.  We can
     still take advantage of the call to find_pc_section, though - the
     object file still must match.  In case we have separate debug
     files, search both the file and its separate debug file.  There's
     no telling which one will have the minimal symbols.  */

  gdb_assert (section != NULL);

  for (objfile *objfile : section->objfile->separate_debug_objfiles ())
    {
      CORE_ADDR pc = pc_in;

      /* If this objfile has a minimal symbol table, go search it
	 using a binary search.  */

      if (objfile->per_bfd->minimal_symbol_count > 0)
	{
	  int best_zero_sized = -1;

	  msymbol = objfile->per_bfd->msymbols.get ();
	  lo = 0;
	  hi = objfile->per_bfd->minimal_symbol_count - 1;

	  /* This code assumes that the minimal symbols are sorted by
	     ascending address values.  If the pc value is greater than or
	     equal to the first symbol's address, then some symbol in this
	     minimal symbol table is a suitable candidate for being the
	     "best" symbol.  This includes the last real symbol, for cases
	     where the pc value is larger than any address in this vector.

	     By iterating until the address associated with the current
	     hi index (the endpoint of the test interval) is less than
	     or equal to the desired pc value, we accomplish two things:
	     (1) the case where the pc value is larger than any minimal
	     symbol address is trivially solved, (2) the address associated
	     with the hi index is always the one we want when the iteration
	     terminates.  In essence, we are iterating the test interval
	     down until the pc value is pushed out of it from the high end.

	     Warning: this code is trickier than it would appear at first.  */

	  unrelocated_addr unrel_pc;
	  if (frob_address (objfile, pc, &unrel_pc)
	      && unrel_pc >= msymbol[lo].unrelocated_address ())
	    {
	      while (msymbol[hi].unrelocated_address () > unrel_pc)
		{
		  /* pc is still strictly less than highest address.  */
		  /* Note "new" will always be >= lo.  */
		  newobj = (lo + hi) / 2;
		  if ((msymbol[newobj].unrelocated_address () >= unrel_pc)
		      || (lo == newobj))
		    {
		      hi = newobj;
		    }
		  else
		    {
		      lo = newobj;
		    }
		}

	      /* If we have multiple symbols at the same address, we want
		 hi to point to the last one.  That way we can find the
		 right symbol if it has an index greater than hi.  */
	      while (hi < objfile->per_bfd->minimal_symbol_count - 1
		     && (msymbol[hi].unrelocated_address ()
			 == msymbol[hi + 1].unrelocated_address ()))
		hi++;

	      /* Skip various undesirable symbols.  */
	      while (hi >= 0)
		{
		  /* Skip any absolute symbols.  This is apparently
		     what adb and dbx do, and is needed for the CM-5.
		     There are two known possible problems: (1) on
		     ELF, apparently end, edata, etc. are absolute.
		     Not sure ignoring them here is a big deal, but if
		     we want to use them, the fix would go in
		     elfread.c.  (2) I think shared library entry
		     points on the NeXT are absolute.  If we want
		     special handling for this it probably should be
		     triggered by a special mst_abs_or_lib or some
		     such.  */

		  if (msymbol[hi].type () == mst_abs)
		    {
		      hi--;
		      continue;
		    }

		  /* If SECTION was specified, skip any symbol from
		     wrong section.  */
		  if (section
		      /* Some types of debug info, such as COFF,
			 don't fill the bfd_section member, so don't
			 throw away symbols on those platforms.  */
		      && msymbol[hi].obj_section (objfile) != nullptr
		      && (!matching_obj_sections
			  (msymbol[hi].obj_section (objfile),
			   section)))
		    {
		      hi--;
		      continue;
		    }

		  /* If we are looking for a trampoline and this is a
		     text symbol, or the other way around, check the
		     preceding symbol too.  If they are otherwise
		     identical prefer that one.  */
		  if (hi > 0
		      && msymbol[hi].type () != want_type
		      && msymbol[hi - 1].type () == want_type
		      && (msymbol[hi].size () == msymbol[hi - 1].size ())
		      && (msymbol[hi].unrelocated_address ()
			  == msymbol[hi - 1].unrelocated_address ())
		      && (msymbol[hi].obj_section (objfile)
			  == msymbol[hi - 1].obj_section (objfile)))
		    {
		      hi--;
		      continue;
		    }

		  /* If the minimal symbol has a zero size, save it
		     but keep scanning backwards looking for one with
		     a non-zero size.  A zero size may mean that the
		     symbol isn't an object or function (e.g. a
		     label), or it may just mean that the size was not
		     specified.  */
		  if (msymbol[hi].size () == 0)
		    {
		      if (best_zero_sized == -1)
			best_zero_sized = hi;
		      hi--;
		      continue;
		    }

		  /* If we are past the end of the current symbol, try
		     the previous symbol if it has a larger overlapping
		     size.  This happens on i686-pc-linux-gnu with glibc;
		     the nocancel variants of system calls are inside
		     the cancellable variants, but both have sizes.  */
		  if (hi > 0
		      && msymbol[hi].size () != 0
		      && unrel_pc >= msymbol[hi].unrelocated_end_address ()
		      && unrel_pc < msymbol[hi - 1].unrelocated_end_address ())
		    {
		      hi--;
		      continue;
		    }

		  /* Otherwise, this symbol must be as good as we're going
		     to get.  */
		  break;
		}

	      /* If HI has a zero size, and best_zero_sized is set,
		 then we had two or more zero-sized symbols; prefer
		 the first one we found (which may have a higher
		 address).  Also, if we ran off the end, be sure
		 to back up.  */
	      if (best_zero_sized != -1
		  && (hi < 0 || msymbol[hi].size () == 0))
		hi = best_zero_sized;

	      /* If the minimal symbol has a non-zero size, and this
		 PC appears to be outside the symbol's contents, then
		 refuse to use this symbol.  If we found a zero-sized
		 symbol with an address greater than this symbol's,
		 use that instead.  We assume that if symbols have
		 specified sizes, they do not overlap.  */

	      if (hi >= 0
		  && msymbol[hi].size () != 0
		  && unrel_pc >= msymbol[hi].unrelocated_end_address ())
		{
		  if (best_zero_sized != -1)
		    hi = best_zero_sized;
		  else
		    {
		      /* If needed record this symbol as the closest
			 previous symbol.  */
		      if (previous != nullptr)
			{
			  if (previous->minsym == nullptr
			      || (msymbol[hi].unrelocated_address ()
				  > previous->minsym->unrelocated_address ()))
			    {
			      previous->minsym = &msymbol[hi];
			      previous->objfile = objfile;
			    }
			}
		      /* Go on to the next object file.  */
		      continue;
		    }
		}

	      /* The minimal symbol indexed by hi now is the best one in this
		 objfile's minimal symbol table.  See if it is the best one
		 overall.  */

	      if (hi >= 0
		  && ((best_symbol == NULL) ||
		      (best_symbol->unrelocated_address () <
		       msymbol[hi].unrelocated_address ())))
		{
		  best_symbol = &msymbol[hi];
		  best_objfile = objfile;
		}
	    }
	}
    }

  result.minsym = best_symbol;
  result.objfile = best_objfile;
  return result;
}

/* See minsyms.h.  */

struct bound_minimal_symbol
lookup_minimal_symbol_by_pc (CORE_ADDR pc)
{
  return lookup_minimal_symbol_by_pc_section (pc, NULL);
}

/* Return non-zero iff PC is in an STT_GNU_IFUNC function resolver.  */

bool
in_gnu_ifunc_stub (CORE_ADDR pc)
{
  bound_minimal_symbol msymbol
    = lookup_minimal_symbol_by_pc_section (pc, NULL,
					   lookup_msym_prefer::GNU_IFUNC);
  return msymbol.minsym && msymbol.minsym->type () == mst_text_gnu_ifunc;
}

/* See elf_gnu_ifunc_resolve_addr for its real implementation.  */

static CORE_ADDR
stub_gnu_ifunc_resolve_addr (struct gdbarch *gdbarch, CORE_ADDR pc)
{
  error (_("GDB cannot resolve STT_GNU_IFUNC symbol at address %s without "
	   "the ELF support compiled in."),
	 paddress (gdbarch, pc));
}

/* See elf_gnu_ifunc_resolve_name for its real implementation.  */

static bool
stub_gnu_ifunc_resolve_name (const char *function_name,
			     CORE_ADDR *function_address_p)
{
  error (_("GDB cannot resolve STT_GNU_IFUNC symbol \"%s\" without "
	   "the ELF support compiled in."),
	 function_name);
}

/* See elf_gnu_ifunc_resolver_stop for its real implementation.  */

static void
stub_gnu_ifunc_resolver_stop (code_breakpoint *b)
{
  internal_error (_("elf_gnu_ifunc_resolver_stop cannot be reached."));
}

/* See elf_gnu_ifunc_resolver_return_stop for its real implementation.  */

static void
stub_gnu_ifunc_resolver_return_stop (code_breakpoint *b)
{
  internal_error (_("elf_gnu_ifunc_resolver_return_stop cannot be reached."));
}

/* See elf_gnu_ifunc_fns for its real implementation.  */

static const struct gnu_ifunc_fns stub_gnu_ifunc_fns =
{
  stub_gnu_ifunc_resolve_addr,
  stub_gnu_ifunc_resolve_name,
  stub_gnu_ifunc_resolver_stop,
  stub_gnu_ifunc_resolver_return_stop,
};

/* A placeholder for &elf_gnu_ifunc_fns.  */

const struct gnu_ifunc_fns *gnu_ifunc_fns_p = &stub_gnu_ifunc_fns;



/* Return leading symbol character for a BFD.  If BFD is NULL,
   return the leading symbol character from the main objfile.  */

static int
get_symbol_leading_char (bfd *abfd)
{
  if (abfd != NULL)
    return bfd_get_symbol_leading_char (abfd);
  if (current_program_space->symfile_object_file != NULL)
    {
      objfile *objf = current_program_space->symfile_object_file;
      if (objf->obfd != NULL)
	return bfd_get_symbol_leading_char (objf->obfd.get ());
    }
  return 0;
}

/* See minsyms.h.  */

minimal_symbol_reader::minimal_symbol_reader (struct objfile *obj)
: m_objfile (obj),
  m_msym_bunch (NULL),
  /* Note that presetting m_msym_bunch_index to BUNCH_SIZE causes the
     first call to save a minimal symbol to allocate the memory for
     the first bunch.  */
  m_msym_bunch_index (BUNCH_SIZE),
  m_msym_count (0)
{
}

/* Discard the currently collected minimal symbols, if any.  If we wish
   to save them for later use, we must have already copied them somewhere
   else before calling this function.  */

minimal_symbol_reader::~minimal_symbol_reader ()
{
  struct msym_bunch *next;

  while (m_msym_bunch != NULL)
    {
      next = m_msym_bunch->next;
      xfree (m_msym_bunch);
      m_msym_bunch = next;
    }
}

/* See minsyms.h.  */

void
minimal_symbol_reader::record (const char *name, unrelocated_addr address,
			       enum minimal_symbol_type ms_type)
{
  int section;

  switch (ms_type)
    {
    case mst_text:
    case mst_text_gnu_ifunc:
    case mst_file_text:
    case mst_solib_trampoline:
      section = SECT_OFF_TEXT (m_objfile);
      break;
    case mst_data:
    case mst_data_gnu_ifunc:
    case mst_file_data:
      section = SECT_OFF_DATA (m_objfile);
      break;
    case mst_bss:
    case mst_file_bss:
      section = SECT_OFF_BSS (m_objfile);
      break;
    default:
      section = -1;
    }

  record_with_info (name, address, ms_type, section);
}

/* Convert an enumerator of type minimal_symbol_type to its string
   representation.  */

static const char *
mst_str (minimal_symbol_type t)
{
#define MST_TO_STR(x) case x: return #x;
  switch (t)
  {
    MST_TO_STR (mst_unknown);
    MST_TO_STR (mst_text);
    MST_TO_STR (mst_text_gnu_ifunc);
    MST_TO_STR (mst_slot_got_plt);
    MST_TO_STR (mst_data);
    MST_TO_STR (mst_bss);
    MST_TO_STR (mst_abs);
    MST_TO_STR (mst_solib_trampoline);
    MST_TO_STR (mst_file_text);
    MST_TO_STR (mst_file_data);
    MST_TO_STR (mst_file_bss);

    default:
      return "mst_???";
  }
#undef MST_TO_STR
}

/* See minsyms.h.  */

struct minimal_symbol *
minimal_symbol_reader::record_full (gdb::string_view name,
				    bool copy_name, unrelocated_addr address,
				    enum minimal_symbol_type ms_type,
				    int section)
{
  struct msym_bunch *newobj;
  struct minimal_symbol *msymbol;

  /* Don't put gcc_compiled, __gnu_compiled_cplus, and friends into
     the minimal symbols, because if there is also another symbol
     at the same address (e.g. the first function of the file),
     lookup_minimal_symbol_by_pc would have no way of getting the
     right one.  */
  if (ms_type == mst_file_text && name[0] == 'g'
      && (name == GCC_COMPILED_FLAG_SYMBOL
	  || name == GCC2_COMPILED_FLAG_SYMBOL))
    return (NULL);

  /* It's safe to strip the leading char here once, since the name
     is also stored stripped in the minimal symbol table.  */
  if (name[0] == get_symbol_leading_char (m_objfile->obfd.get ()))
    name = name.substr (1);

  if (ms_type == mst_file_text && startswith (name, "__gnu_compiled"))
    return (NULL);

  symtab_create_debug_printf_v ("recording minsym:  %-21s  %18s  %4d  %.*s",
				mst_str (ms_type),
				hex_string (LONGEST (address)),
				section, (int) name.size (), name.data ());

  if (m_msym_bunch_index == BUNCH_SIZE)
    {
      newobj = XCNEW (struct msym_bunch);
      m_msym_bunch_index = 0;
      newobj->next = m_msym_bunch;
      m_msym_bunch = newobj;
    }
  msymbol = &m_msym_bunch->contents[m_msym_bunch_index];
  msymbol->set_language (language_unknown,
			 &m_objfile->per_bfd->storage_obstack);

  if (copy_name)
    msymbol->m_name = obstack_strndup (&m_objfile->per_bfd->storage_obstack,
				       name.data (), name.size ());
  else
    msymbol->m_name = name.data ();

  msymbol->set_unrelocated_address (address);
  msymbol->set_section_index (section);

  msymbol->set_type (ms_type);

  /* If we already read minimal symbols for this objfile, then don't
     ever allocate a new one.  */
  if (!m_objfile->per_bfd->minsyms_read)
    {
      m_msym_bunch_index++;
      m_objfile->per_bfd->n_minsyms++;
    }
  m_msym_count++;
  return msymbol;
}

/* Compare two minimal symbols by address and return true if FN1's address
   is less than FN2's, so that we sort into unsigned numeric order.
   Within groups with the same address, sort by name.  */

static inline bool
minimal_symbol_is_less_than (const minimal_symbol &fn1,
			     const minimal_symbol &fn2)
{
  if ((&fn1)->unrelocated_address () < (&fn2)->unrelocated_address ())
    {
      return true;		/* addr 1 is less than addr 2.  */
    }
  else if ((&fn1)->unrelocated_address () > (&fn2)->unrelocated_address ())
    {
      return false;		/* addr 1 is greater than addr 2.  */
    }
  else
    /* addrs are equal: sort by name */
    {
      const char *name1 = fn1.linkage_name ();
      const char *name2 = fn2.linkage_name ();

      if (name1 && name2)	/* both have names */
	return strcmp (name1, name2) < 0;
      else if (name2)
	return true;		/* fn1 has no name, so it is "less".  */
      else if (name1)		/* fn2 has no name, so it is "less".  */
	return false;
      else
	return false;		/* Neither has a name, so they're equal.  */
    }
}

/* Compact duplicate entries out of a minimal symbol table by walking
   through the table and compacting out entries with duplicate addresses
   and matching names.  Return the number of entries remaining.

   On entry, the table resides between msymbol[0] and msymbol[mcount].
   On exit, it resides between msymbol[0] and msymbol[result_count].

   When files contain multiple sources of symbol information, it is
   possible for the minimal symbol table to contain many duplicate entries.
   As an example, SVR4 systems use ELF formatted object files, which
   usually contain at least two different types of symbol tables (a
   standard ELF one and a smaller dynamic linking table), as well as
   DWARF debugging information for files compiled with -g.

   Without compacting, the minimal symbol table for gdb itself contains
   over a 1000 duplicates, about a third of the total table size.  Aside
   from the potential trap of not noticing that two successive entries
   identify the same location, this duplication impacts the time required
   to linearly scan the table, which is done in a number of places.  So we
   just do one linear scan here and toss out the duplicates.

   Since the different sources of information for each symbol may
   have different levels of "completeness", we may have duplicates
   that have one entry with type "mst_unknown" and the other with a
   known type.  So if the one we are leaving alone has type mst_unknown,
   overwrite its type with the type from the one we are compacting out.  */

static int
compact_minimal_symbols (struct minimal_symbol *msymbol, int mcount,
			 struct objfile *objfile)
{
  struct minimal_symbol *copyfrom;
  struct minimal_symbol *copyto;

  if (mcount > 0)
    {
      copyfrom = copyto = msymbol;
      while (copyfrom < msymbol + mcount - 1)
	{
	  if (copyfrom->unrelocated_address ()
	      == (copyfrom + 1)->unrelocated_address ()
	      && (copyfrom->section_index ()
		  == (copyfrom + 1)->section_index ())
	      && strcmp (copyfrom->linkage_name (),
			 (copyfrom + 1)->linkage_name ()) == 0)
	    {
	      if ((copyfrom + 1)->type () == mst_unknown)
		(copyfrom + 1)->set_type (copyfrom->type ());

	      copyfrom++;
	    }
	  else
	    *copyto++ = *copyfrom++;
	}
      *copyto++ = *copyfrom++;
      mcount = copyto - msymbol;
    }
  return (mcount);
}

static void
clear_minimal_symbol_hash_tables (struct objfile *objfile)
{
  for (size_t i = 0; i < MINIMAL_SYMBOL_HASH_SIZE; i++)
    {
      objfile->per_bfd->msymbol_hash[i] = 0;
      objfile->per_bfd->msymbol_demangled_hash[i] = 0;
    }
}

/* This struct is used to store values we compute for msymbols on the
   background threads but don't need to keep around long term.  */
struct computed_hash_values
{
  /* Length of the linkage_name of the symbol.  */
  size_t name_length;
  /* Hash code (using fast_hash) of the linkage_name.  */
  hashval_t mangled_name_hash;
  /* The msymbol_hash of the linkage_name.  */
  unsigned int minsym_hash;
  /* The msymbol_hash of the search_name.  */
  unsigned int minsym_demangled_hash;
};

/* Build (or rebuild) the minimal symbol hash tables.  This is necessary
   after compacting or sorting the table since the entries move around
   thus causing the internal minimal_symbol pointers to become jumbled.  */
  
static void
build_minimal_symbol_hash_tables
  (struct objfile *objfile,
   const std::vector<computed_hash_values>& hash_values)
{
  int i;
  struct minimal_symbol *msym;

  /* (Re)insert the actual entries.  */
  int mcount = objfile->per_bfd->minimal_symbol_count;
  for ((i = 0,
	msym = objfile->per_bfd->msymbols.get ());
       i < mcount;
       i++, msym++)
    {
      msym->hash_next = 0;
      add_minsym_to_hash_table (msym, objfile->per_bfd->msymbol_hash,
				hash_values[i].minsym_hash);

      msym->demangled_hash_next = 0;
      if (msym->search_name () != msym->linkage_name ())
	add_minsym_to_demangled_hash_table
	  (msym, objfile, hash_values[i].minsym_demangled_hash);
    }
}

/* Add the minimal symbols in the existing bunches to the objfile's official
   minimal symbol table.  In most cases there is no minimal symbol table yet
   for this objfile, and the existing bunches are used to create one.  Once
   in a while (for shared libraries for example), we add symbols (e.g. common
   symbols) to an existing objfile.  */

void
minimal_symbol_reader::install ()
{
  int mcount;
  struct msym_bunch *bunch;
  struct minimal_symbol *msymbols;
  int alloc_count;

  if (m_objfile->per_bfd->minsyms_read)
    return;

  if (m_msym_count > 0)
    {
      symtab_create_debug_printf ("installing %d minimal symbols of objfile %s",
				  m_msym_count, objfile_name (m_objfile));

      /* Allocate enough space, into which we will gather the bunches
	 of new and existing minimal symbols, sort them, and then
	 compact out the duplicate entries.  Once we have a final
	 table, we will give back the excess space.  */

      alloc_count = m_msym_count + m_objfile->per_bfd->minimal_symbol_count;
      gdb::unique_xmalloc_ptr<minimal_symbol>
	msym_holder (XNEWVEC (minimal_symbol, alloc_count));
      msymbols = msym_holder.get ();

      /* Copy in the existing minimal symbols, if there are any.  */

      if (m_objfile->per_bfd->minimal_symbol_count)
	memcpy (msymbols, m_objfile->per_bfd->msymbols.get (),
		m_objfile->per_bfd->minimal_symbol_count
		* sizeof (struct minimal_symbol));

      /* Walk through the list of minimal symbol bunches, adding each symbol
	 to the new contiguous array of symbols.  Note that we start with the
	 current, possibly partially filled bunch (thus we use the current
	 msym_bunch_index for the first bunch we copy over), and thereafter
	 each bunch is full.  */

      mcount = m_objfile->per_bfd->minimal_symbol_count;

      for (bunch = m_msym_bunch; bunch != NULL; bunch = bunch->next)
	{
	  memcpy (&msymbols[mcount], &bunch->contents[0],
		  m_msym_bunch_index * sizeof (struct minimal_symbol));
	  mcount += m_msym_bunch_index;
	  m_msym_bunch_index = BUNCH_SIZE;
	}

      /* Sort the minimal symbols by address.  */

      std::sort (msymbols, msymbols + mcount, minimal_symbol_is_less_than);

      /* Compact out any duplicates, and free up whatever space we are
	 no longer using.  */

      mcount = compact_minimal_symbols (msymbols, mcount, m_objfile);
      msym_holder.reset (XRESIZEVEC (struct minimal_symbol,
				     msym_holder.release (),
				     mcount));

      /* Attach the minimal symbol table to the specified objfile.
	 The strings themselves are also located in the storage_obstack
	 of this objfile.  */

      if (m_objfile->per_bfd->minimal_symbol_count != 0)
	clear_minimal_symbol_hash_tables (m_objfile);

      m_objfile->per_bfd->minimal_symbol_count = mcount;
      m_objfile->per_bfd->msymbols = std::move (msym_holder);

#if CXX_STD_THREAD
      /* Mutex that is used when modifying or accessing the demangled
	 hash table.  */
      std::mutex demangled_mutex;
#endif

      std::vector<computed_hash_values> hash_values (mcount);

      msymbols = m_objfile->per_bfd->msymbols.get ();
      /* Arbitrarily require at least 10 elements in a thread.  */
      gdb::parallel_for_each (10, &msymbols[0], &msymbols[mcount],
	 [&] (minimal_symbol *start, minimal_symbol *end)
	 {
	   for (minimal_symbol *msym = start; msym < end; ++msym)
	     {
	       size_t idx = msym - msymbols;
	       hash_values[idx].name_length = strlen (msym->linkage_name ());
	       if (!msym->name_set)
		 {
		   /* This will be freed later, by compute_and_set_names.  */
		   gdb::unique_xmalloc_ptr<char> demangled_name
		     = symbol_find_demangled_name (msym, msym->linkage_name ());
		   msym->set_demangled_name
		     (demangled_name.release (),
		      &m_objfile->per_bfd->storage_obstack);
		   msym->name_set = 1;
		 }
	       /* This mangled_name_hash computation has to be outside of
		  the name_set check, or compute_and_set_names below will
		  be called with an invalid hash value.  */
	       hash_values[idx].mangled_name_hash
		 = fast_hash (msym->linkage_name (),
			      hash_values[idx].name_length);
	       hash_values[idx].minsym_hash
		 = msymbol_hash (msym->linkage_name ());
	       /* We only use this hash code if the search name differs
		  from the linkage name.  See the code in
		  build_minimal_symbol_hash_tables.  */
	       if (msym->search_name () != msym->linkage_name ())
		 hash_values[idx].minsym_demangled_hash
		   = search_name_hash (msym->language (), msym->search_name ());
	     }
	   {
	     /* To limit how long we hold the lock, we only acquire it here
		and not while we demangle the names above.  */
#if CXX_STD_THREAD
	     std::lock_guard<std::mutex> guard (demangled_mutex);
#endif
	     for (minimal_symbol *msym = start; msym < end; ++msym)
	       {
		 size_t idx = msym - msymbols;
		 msym->compute_and_set_names
		   (gdb::string_view (msym->linkage_name (),
				      hash_values[idx].name_length),
		    false,
		    m_objfile->per_bfd,
		    hash_values[idx].mangled_name_hash);
	       }
	   }
	 });

      build_minimal_symbol_hash_tables (m_objfile, hash_values);
    }
}

/* Check if PC is in a shared library trampoline code stub.
   Return minimal symbol for the trampoline entry or NULL if PC is not
   in a trampoline code stub.  */

static struct minimal_symbol *
lookup_solib_trampoline_symbol_by_pc (CORE_ADDR pc)
{
  bound_minimal_symbol msymbol
    = lookup_minimal_symbol_by_pc_section (pc, NULL,
					   lookup_msym_prefer::TRAMPOLINE);

  if (msymbol.minsym != NULL
      && msymbol.minsym->type () == mst_solib_trampoline)
    return msymbol.minsym;
  return NULL;
}

/* If PC is in a shared library trampoline code stub, return the
   address of the `real' function belonging to the stub.
   Return 0 if PC is not in a trampoline code stub or if the real
   function is not found in the minimal symbol table.

   We may fail to find the right function if a function with the
   same name is defined in more than one shared library, but this
   is considered bad programming style.  We could return 0 if we find
   a duplicate function in case this matters someday.  */

CORE_ADDR
find_solib_trampoline_target (frame_info_ptr frame, CORE_ADDR pc)
{
  struct minimal_symbol *tsymbol = lookup_solib_trampoline_symbol_by_pc (pc);

  if (tsymbol != NULL)
    {
      for (objfile *objfile : current_program_space->objfiles ())
	{
	  for (minimal_symbol *msymbol : objfile->msymbols ())
	    {
	      /* Also handle minimal symbols pointing to function
		 descriptors.  */
	      if ((msymbol->type () == mst_text
		   || msymbol->type () == mst_text_gnu_ifunc
		   || msymbol->type () == mst_data
		   || msymbol->type () == mst_data_gnu_ifunc)
		  && strcmp (msymbol->linkage_name (),
			     tsymbol->linkage_name ()) == 0)
		{
		  CORE_ADDR func;

		  /* Ignore data symbols that are not function
		     descriptors.  */
		  if (msymbol_is_function (objfile, msymbol, &func))
		    return func;
		}
	    }
	}
    }
  return 0;
}

/* See minsyms.h.  */

CORE_ADDR
minimal_symbol_upper_bound (struct bound_minimal_symbol minsym)
{
  short section;
  struct obj_section *obj_section;
  CORE_ADDR result;
  struct minimal_symbol *iter, *msymbol;

  gdb_assert (minsym.minsym != NULL);

  /* If the minimal symbol has a size, use it.  Otherwise use the
     lesser of the next minimal symbol in the same section, or the end
     of the section, as the end of the function.  */

  if (minsym.minsym->size () != 0)
    return minsym.value_address () + minsym.minsym->size ();

  /* Step over other symbols at this same address, and symbols in
     other sections, to find the next symbol in this section with a
     different address.  */

  struct minimal_symbol *past_the_end
    = (minsym.objfile->per_bfd->msymbols.get ()
       + minsym.objfile->per_bfd->minimal_symbol_count);
  msymbol = minsym.minsym;
  section = msymbol->section_index ();
  for (iter = msymbol + 1; iter != past_the_end; ++iter)
    {
      if ((iter->unrelocated_address ()
	   != msymbol->unrelocated_address ())
	  && iter->section_index () == section)
	break;
    }

  obj_section = minsym.obj_section ();
  if (iter != past_the_end
      && (iter->value_address (minsym.objfile)
	  < obj_section->endaddr ()))
    result = iter->value_address (minsym.objfile);
  else
    /* We got the start address from the last msymbol in the objfile.
       So the end address is the end of the section.  */
    result = obj_section->endaddr ();

  return result;
}

/* See minsyms.h.  */

type *
find_minsym_type_and_address (minimal_symbol *msymbol,
			      struct objfile *objfile,
			      CORE_ADDR *address_p)
{
  bound_minimal_symbol bound_msym = {msymbol, objfile};
  struct obj_section *section = msymbol->obj_section (objfile);
  enum minimal_symbol_type type = msymbol->type ();

  bool is_tls = (section != NULL
		 && section->the_bfd_section->flags & SEC_THREAD_LOCAL);

  /* The minimal symbol might point to a function descriptor;
     resolve it to the actual code address instead.  */
  CORE_ADDR addr;
  if (is_tls)
    {
      /* Addresses of TLS symbols are really offsets into a
	 per-objfile/per-thread storage block.  */
      addr = CORE_ADDR (bound_msym.minsym->unrelocated_address ());
    }
  else if (msymbol_is_function (objfile, msymbol, &addr))
    {
      if (addr != bound_msym.value_address ())
	{
	  /* This means we resolved a function descriptor, and we now
	     have an address for a code/text symbol instead of a data
	     symbol.  */
	  if (msymbol->type () == mst_data_gnu_ifunc)
	    type = mst_text_gnu_ifunc;
	  else
	    type = mst_text;
	  section = NULL;
	}
    }
  else
    addr = bound_msym.value_address ();

  if (overlay_debugging)
    addr = symbol_overlayed_address (addr, section);

  if (is_tls)
    {
      /* Skip translation if caller does not need the address.  */
      if (address_p != NULL)
	*address_p = target_translate_tls_address (objfile, addr);
      return builtin_type (objfile)->nodebug_tls_symbol;
    }

  if (address_p != NULL)
    *address_p = addr;

  switch (type)
    {
    case mst_text:
    case mst_file_text:
    case mst_solib_trampoline:
      return builtin_type (objfile)->nodebug_text_symbol;

    case mst_text_gnu_ifunc:
      return builtin_type (objfile)->nodebug_text_gnu_ifunc_symbol;

    case mst_data:
    case mst_file_data:
    case mst_bss:
    case mst_file_bss:
      return builtin_type (objfile)->nodebug_data_symbol;

    case mst_slot_got_plt:
      return builtin_type (objfile)->nodebug_got_plt_symbol;

    default:
      return builtin_type (objfile)->nodebug_unknown_symbol;
    }
}