summaryrefslogtreecommitdiff
path: root/gdb/minsyms.c
blob: b1ef28ffa5feae4140a01a55fed1f713eaa5fede (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
/* GDB routines for manipulating the minimal symbol tables.
   Copyright 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001
   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 2 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, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */


/* 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 "gdb_string.h"
#include "symtab.h"
#include "bfd.h"
#include "symfile.h"
#include "objfiles.h"
#include "demangle.h"
#include "value.h"
#include "cp-abi.h"

/* Accumulate the minimal symbols for each objfile in bunches of BUNCH_SIZE.
   At the end, copy them all into one newly allocated location on an objfile's
   symbol obstack.  */

#define BUNCH_SIZE 127

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

/* Bunch currently being filled up.
   The next field points to chain of filled bunches.  */

static struct msym_bunch *msym_bunch;

/* Number of slots filled in current bunch.  */

static int msym_bunch_index;

/* Total number of minimal symbols recorded so far for the objfile.  */

static int msym_count;

/* Compute a hash code based using the same criteria as `strcmp_iw'.  */

unsigned int
msymbol_hash_iw (const char *string)
{
  unsigned int hash = 0;
  while (*string && *string != '(')
    {
      while (isspace (*string))
	++string;
      if (*string && *string != '(')
	{
	  hash = hash * 67 + *string - 113;
	  ++string;
	}
    }
  return hash;
}

/* Compute a hash code for a string.  */

unsigned int
msymbol_hash (const char *string)
{
  unsigned int hash = 0;
  for (; *string; ++string)
    hash = hash * 67 + *string - 113;
  return hash;
}

/* Add the minimal symbol SYM to an objfile's minsym hash table, TABLE.  */
void
add_minsym_to_hash_table (struct minimal_symbol *sym,
			  struct minimal_symbol **table)
{
  if (sym->hash_next == NULL)
    {
      unsigned int hash = msymbol_hash (SYMBOL_NAME (sym)) % 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 minimal_symbol **table)
{
  if (sym->demangled_hash_next == NULL)
    {
      unsigned int hash = msymbol_hash_iw (SYMBOL_DEMANGLED_NAME (sym)) % MINIMAL_SYMBOL_HASH_SIZE;
      sym->demangled_hash_next = table[hash];
      table[hash] = sym;
    }
}


/* 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, limit the search
   to that source file.  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). */

struct minimal_symbol *
lookup_minimal_symbol (register const char *name, const char *sfile,
		       struct objfile *objf)
{
  struct objfile *objfile;
  struct minimal_symbol *msymbol;
  struct minimal_symbol *found_symbol = NULL;
  struct minimal_symbol *found_file_symbol = NULL;
  struct minimal_symbol *trampoline_symbol = NULL;

  unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;
  unsigned int dem_hash = msymbol_hash_iw (name) % MINIMAL_SYMBOL_HASH_SIZE;

#ifdef SOFUN_ADDRESS_MAYBE_MISSING
  if (sfile != NULL)
    {
      char *p = strrchr (sfile, '/');
      if (p != NULL)
	sfile = p + 1;
    }
#endif

  for (objfile = object_files;
       objfile != NULL && found_symbol == NULL;
       objfile = objfile->next)
    {
      if (objf == NULL || objf == objfile)
	{
	  /* Do two passes: the first over the ordinary hash table,
	     and the second over the demangled hash table.  */
        int pass;

        for (pass = 1; pass <= 2 && found_symbol == NULL; pass++)
	    {
            /* Select hash list according to pass.  */
            if (pass == 1)
              msymbol = objfile->msymbol_hash[hash];
            else
              msymbol = objfile->msymbol_demangled_hash[dem_hash];

            while (msymbol != NULL && found_symbol == NULL)
		{
                if (SYMBOL_MATCHES_NAME (msymbol, name))
		    {
                    switch (MSYMBOL_TYPE (msymbol))
                      {
                      case mst_file_text:
                      case mst_file_data:
                      case mst_file_bss:
#ifdef SOFUN_ADDRESS_MAYBE_MISSING
                        if (sfile == NULL || STREQ (msymbol->filename, sfile))
                          found_file_symbol = msymbol;
#else
                        /* We have neither the ability nor the need to
                           deal with the SFILE parameter.  If we find
                           more than one symbol, just return the latest
                           one (the user can't expect useful behavior in
                           that case).  */
                        found_file_symbol = msymbol;
#endif
                        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 == NULL)
                          trampoline_symbol = msymbol;
                        break;

                      case mst_unknown:
                      default:
                        found_symbol = msymbol;
                        break;
                      }
		    }

                /* Find the next symbol on the hash chain.  */
                if (pass == 1)
                  msymbol = msymbol->hash_next;
                else
                  msymbol = msymbol->demangled_hash_next;
		}
	    }
	}
    }
  /* External symbols are best.  */
  if (found_symbol)
    return found_symbol;

  /* File-local symbols are next best.  */
  if (found_file_symbol)
    return found_file_symbol;

  /* Symbols for shared library trampolines are next best.  */
  if (trampoline_symbol)
    return trampoline_symbol;

  return NULL;
}

/* Look through all the current minimal symbol tables and find the
   first minimal symbol that matches NAME and of text type.  
   If OBJF is non-NULL, limit
   the search to that objfile.  If SFILE is non-NULL, limit the search
   to that source file.  Returns a pointer to the minimal symbol that
   matches, or NULL if no match is found.
 */

struct minimal_symbol *
lookup_minimal_symbol_text (register const char *name, const char *sfile,
			    struct objfile *objf)
{
  struct objfile *objfile;
  struct minimal_symbol *msymbol;
  struct minimal_symbol *found_symbol = NULL;
  struct minimal_symbol *found_file_symbol = NULL;

#ifdef SOFUN_ADDRESS_MAYBE_MISSING
  if (sfile != NULL)
    {
      char *p = strrchr (sfile, '/');
      if (p != NULL)
	sfile = p + 1;
    }
#endif

  for (objfile = object_files;
       objfile != NULL && found_symbol == NULL;
       objfile = objfile->next)
    {
      if (objf == NULL || objf == objfile)
	{
	  for (msymbol = objfile->msymbols;
	       msymbol != NULL && SYMBOL_NAME (msymbol) != NULL &&
	       found_symbol == NULL;
	       msymbol++)
	    {
	      if (SYMBOL_MATCHES_NAME (msymbol, name) &&
		  (MSYMBOL_TYPE (msymbol) == mst_text ||
		   MSYMBOL_TYPE (msymbol) == mst_file_text))
		{
		  switch (MSYMBOL_TYPE (msymbol))
		    {
		    case mst_file_text:
#ifdef SOFUN_ADDRESS_MAYBE_MISSING
		      if (sfile == NULL || STREQ (msymbol->filename, sfile))
			found_file_symbol = msymbol;
#else
		      /* We have neither the ability nor the need to
		         deal with the SFILE parameter.  If we find
		         more than one symbol, just return the latest
		         one (the user can't expect useful behavior in
		         that case).  */
		      found_file_symbol = msymbol;
#endif
		      break;
		    default:
		      found_symbol = msymbol;
		      break;
		    }
		}
	    }
	}
    }
  /* External symbols are best.  */
  if (found_symbol)
    return found_symbol;

  /* File-local symbols are next best.  */
  if (found_file_symbol)
    return found_file_symbol;

  return NULL;
}

/* Look through all the current minimal symbol tables and find the
   first minimal symbol that matches NAME and of solib trampoline type.  
   If OBJF is non-NULL, limit
   the search to that objfile.  If SFILE is non-NULL, limit the search
   to that source file.  Returns a pointer to the minimal symbol that
   matches, or NULL if no match is found.
 */

struct minimal_symbol *
lookup_minimal_symbol_solib_trampoline (register const char *name,
					const char *sfile, struct objfile *objf)
{
  struct objfile *objfile;
  struct minimal_symbol *msymbol;
  struct minimal_symbol *found_symbol = NULL;

#ifdef SOFUN_ADDRESS_MAYBE_MISSING
  if (sfile != NULL)
    {
      char *p = strrchr (sfile, '/');
      if (p != NULL)
	sfile = p + 1;
    }
#endif

  for (objfile = object_files;
       objfile != NULL && found_symbol == NULL;
       objfile = objfile->next)
    {
      if (objf == NULL || objf == objfile)
	{
	  for (msymbol = objfile->msymbols;
	       msymbol != NULL && SYMBOL_NAME (msymbol) != NULL &&
	       found_symbol == NULL;
	       msymbol++)
	    {
	      if (SYMBOL_MATCHES_NAME (msymbol, name) &&
		  MSYMBOL_TYPE (msymbol) == mst_solib_trampoline)
		return msymbol;
	    }
	}
    }

  return NULL;
}


/* Search through the minimal symbol table for each objfile and find
   the symbol whose address is the largest address that is still less
   than or equal to PC, and matches SECTION (if non-null).  Returns a
   pointer to the minimal symbol if such a symbol is found, or NULL if
   PC is not in a suitable range.  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.  */

struct minimal_symbol *
lookup_minimal_symbol_by_pc_section (CORE_ADDR pc, asection *section)
{
  int lo;
  int hi;
  int new;
  struct objfile *objfile;
  struct minimal_symbol *msymbol;
  struct minimal_symbol *best_symbol = NULL;

  /* pc has to be in a known section. This ensures that anything beyond
     the end of the last segment doesn't appear to be part of the last
     function in the last segment.  */
  if (find_pc_section (pc) == NULL)
    return NULL;

  for (objfile = object_files;
       objfile != NULL;
       objfile = objfile->next)
    {
      /* If this objfile has a minimal symbol table, go search it using
         a binary search.  Note that a minimal symbol table always consists
         of at least two symbols, a "real" symbol and the terminating
         "null symbol".  If there are no real symbols, then there is no
         minimal symbol table at all. */

      if ((msymbol = objfile->msymbols) != NULL)
	{
	  lo = 0;
	  hi = objfile->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 interation
	     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. */

	  /* Should also require that pc is <= end of objfile.  FIXME! */
	  if (pc >= SYMBOL_VALUE_ADDRESS (&msymbol[lo]))
	    {
	      while (SYMBOL_VALUE_ADDRESS (&msymbol[hi]) > pc)
		{
		  /* pc is still strictly less than highest address */
		  /* Note "new" will always be >= lo */
		  new = (lo + hi) / 2;
		  if ((SYMBOL_VALUE_ADDRESS (&msymbol[new]) >= pc) ||
		      (lo == new))
		    {
		      hi = new;
		    }
		  else
		    {
		      lo = new;
		    }
		}

	      /* 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->minimal_symbol_count - 1
		     && (SYMBOL_VALUE_ADDRESS (&msymbol[hi])
			 == SYMBOL_VALUE_ADDRESS (&msymbol[hi + 1])))
		hi++;

	      /* 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. */

	      /* 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.  */
	      while (hi >= 0
		     && msymbol[hi].type == mst_abs)
		--hi;

	      /* If "section" specified, skip any symbol from wrong section */
	      /* This is the new code that distinguishes it from the old function */
	      if (section)
		while (hi >= 0
		       /* Some types of debug info, such as COFF,
			  don't fill the bfd_section member, so don't
			  throw away symbols on those platforms.  */
		       && SYMBOL_BFD_SECTION (&msymbol[hi]) != NULL
		       && SYMBOL_BFD_SECTION (&msymbol[hi]) != section)
		  --hi;

	      if (hi >= 0
		  && ((best_symbol == NULL) ||
		      (SYMBOL_VALUE_ADDRESS (best_symbol) <
		       SYMBOL_VALUE_ADDRESS (&msymbol[hi]))))
		{
		  best_symbol = &msymbol[hi];
		}
	    }
	}
    }
  return (best_symbol);
}

/* Backward compatibility: search through the minimal symbol table 
   for a matching PC (no section given) */

struct minimal_symbol *
lookup_minimal_symbol_by_pc (CORE_ADDR pc)
{
  return lookup_minimal_symbol_by_pc_section (pc, find_pc_mapped_section (pc));
}


/* 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 *);

static int
get_symbol_leading_char (bfd *abfd)
{
  if (abfd != NULL)
    return bfd_get_symbol_leading_char (abfd);
  if (symfile_objfile != NULL && symfile_objfile->obfd != NULL)
    return bfd_get_symbol_leading_char (symfile_objfile->obfd);
  return 0;
}

/* Prepare to start collecting minimal symbols.  Note that presetting
   msym_bunch_index to BUNCH_SIZE causes the first call to save a minimal
   symbol to allocate the memory for the first bunch. */

void
init_minimal_symbol_collection (void)
{
  msym_count = 0;
  msym_bunch = NULL;
  msym_bunch_index = BUNCH_SIZE;
}

void
prim_record_minimal_symbol (const char *name, CORE_ADDR address,
			    enum minimal_symbol_type ms_type,
			    struct objfile *objfile)
{
  int section;

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

  prim_record_minimal_symbol_and_info (name, address, ms_type,
				       NULL, section, NULL, objfile);
}

/* Record a minimal symbol in the msym bunches.  Returns the symbol
   newly created.  */

struct minimal_symbol *
prim_record_minimal_symbol_and_info (const char *name, CORE_ADDR address,
				     enum minimal_symbol_type ms_type,
				     char *info, int section,
				     asection *bfd_section,
				     struct objfile *objfile)
{
  register struct msym_bunch *new;
  register struct minimal_symbol *msymbol;

  if (ms_type == mst_file_text)
    {
      /* 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 (name[0] == 'g'
	  && (strcmp (name, GCC_COMPILED_FLAG_SYMBOL) == 0
	      || strcmp (name, GCC2_COMPILED_FLAG_SYMBOL) == 0))
	return (NULL);

      {
	const char *tempstring = name;
	if (tempstring[0] == get_symbol_leading_char (objfile->obfd))
	  ++tempstring;
	if (STREQN (tempstring, "__gnu_compiled", 14))
	  return (NULL);
      }
    }

  if (msym_bunch_index == BUNCH_SIZE)
    {
      new = (struct msym_bunch *) xmalloc (sizeof (struct msym_bunch));
      msym_bunch_index = 0;
      new->next = msym_bunch;
      msym_bunch = new;
    }
  msymbol = &msym_bunch->contents[msym_bunch_index];
  SYMBOL_NAME (msymbol) = obsavestring ((char *) name, strlen (name),
					&objfile->symbol_obstack);
  SYMBOL_INIT_LANGUAGE_SPECIFIC (msymbol, language_unknown);
  SYMBOL_VALUE_ADDRESS (msymbol) = address;
  SYMBOL_SECTION (msymbol) = section;
  SYMBOL_BFD_SECTION (msymbol) = bfd_section;

  MSYMBOL_TYPE (msymbol) = ms_type;
  /* FIXME:  This info, if it remains, needs its own field.  */
  MSYMBOL_INFO (msymbol) = info;	/* FIXME! */

  /* The hash pointers must be cleared! If they're not,
     add_minsym_to_hash_table will NOT add this msymbol to the hash table. */
  msymbol->hash_next = NULL;
  msymbol->demangled_hash_next = NULL;

  msym_bunch_index++;
  msym_count++;
  OBJSTAT (objfile, n_minsyms++);
  return msymbol;
}

/* Compare two minimal symbols by address and return a signed result based
   on unsigned comparisons, so that we sort into unsigned numeric order.  
   Within groups with the same address, sort by name.  */

static int
compare_minimal_symbols (const void *fn1p, const void *fn2p)
{
  register const struct minimal_symbol *fn1;
  register const struct minimal_symbol *fn2;

  fn1 = (const struct minimal_symbol *) fn1p;
  fn2 = (const struct minimal_symbol *) fn2p;

  if (SYMBOL_VALUE_ADDRESS (fn1) < SYMBOL_VALUE_ADDRESS (fn2))
    {
      return (-1);		/* addr 1 is less than addr 2 */
    }
  else if (SYMBOL_VALUE_ADDRESS (fn1) > SYMBOL_VALUE_ADDRESS (fn2))
    {
      return (1);		/* addr 1 is greater than addr 2 */
    }
  else
    /* addrs are equal: sort by name */
    {
      char *name1 = SYMBOL_NAME (fn1);
      char *name2 = SYMBOL_NAME (fn2);

      if (name1 && name2)	/* both have names */
	return strcmp (name1, name2);
      else if (name2)
	return 1;		/* fn1 has no name, so it is "less" */
      else if (name1)		/* fn2 has no name, so it is "less" */
	return -1;
      else
	return (0);		/* neither has a name, so they're equal. */
    }
}

/* 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.

   FIXME:  We could allocate the minimal symbol bunches on their own
   obstack and then simply blow the obstack away when we are done with
   it.  Is it worth the extra trouble though? */

static void
do_discard_minimal_symbols_cleanup (void *arg)
{
  register struct msym_bunch *next;

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

struct cleanup *
make_cleanup_discard_minimal_symbols (void)
{
  return make_cleanup (do_discard_minimal_symbols_cleanup, 0);
}



/* 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.

   Note that we are not concerned here about recovering the space that
   is potentially freed up, because the strings themselves are allocated
   on the symbol_obstack, and will get automatically freed when the symbol
   table is freed.  The caller can free up the unused minimal symbols at
   the end of the compacted region if their allocation strategy allows it.

   Also note we only go up to the next to last entry within the loop
   and then copy the last entry explicitly after the loop terminates.

   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 (SYMBOL_VALUE_ADDRESS (copyfrom) ==
	      SYMBOL_VALUE_ADDRESS ((copyfrom + 1)) &&
	      (STREQ (SYMBOL_NAME (copyfrom), SYMBOL_NAME ((copyfrom + 1)))))
	    {
	      if (MSYMBOL_TYPE ((copyfrom + 1)) == mst_unknown)
		{
		  MSYMBOL_TYPE ((copyfrom + 1)) = MSYMBOL_TYPE (copyfrom);
		}
	      copyfrom++;
	    }
	  else
	    *copyto++ = *copyfrom++;
	}
      *copyto++ = *copyfrom++;
      mcount = copyto - msymbol;
    }
  return (mcount);
}

/* 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)
{
  int i;
  struct minimal_symbol *msym;

  /* Clear the hash tables. */
  for (i = 0; i < MINIMAL_SYMBOL_HASH_SIZE; i++)
    {
      objfile->msymbol_hash[i] = 0;
      objfile->msymbol_demangled_hash[i] = 0;
    }

  /* Now, (re)insert the actual entries. */
  for (i = objfile->minimal_symbol_count, msym = objfile->msymbols;
       i > 0;
       i--, msym++)
    {
      msym->hash_next = 0;
      add_minsym_to_hash_table (msym, objfile->msymbol_hash);

      msym->demangled_hash_next = 0;
      if (SYMBOL_DEMANGLED_NAME (msym) != NULL)
	add_minsym_to_demangled_hash_table (msym,
                                            objfile->msymbol_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.

   Because of the way minimal symbols are collected, we generally have no way
   of knowing what source language applies to any particular minimal symbol.
   Specifically, we have no way of knowing if the minimal symbol comes from a
   C++ compilation unit or not.  So for the sake of supporting cached
   demangled C++ names, we have no choice but to try and demangle each new one
   that comes in.  If the demangling succeeds, then we assume it is a C++
   symbol and set the symbol's language and demangled name fields
   appropriately.  Note that in order to avoid unnecessary demanglings, and
   allocating obstack space that subsequently can't be freed for the demangled
   names, we mark all newly added symbols with language_auto.  After
   compaction of the minimal symbols, we go back and scan the entire minimal
   symbol table looking for these new symbols.  For each new symbol we attempt
   to demangle it, and if successful, record it as a language_cplus symbol
   and cache the demangled form on the symbol obstack.  Symbols which don't
   demangle are marked as language_unknown symbols, which inhibits future
   attempts to demangle them if we later add more minimal symbols. */

void
install_minimal_symbols (struct objfile *objfile)
{
  register int bindex;
  register int mcount;
  register struct msym_bunch *bunch;
  register struct minimal_symbol *msymbols;
  int alloc_count;
  register char leading_char;

  if (msym_count > 0)
    {
      /* Allocate enough space in the obstack, 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 = msym_count + objfile->minimal_symbol_count + 1;
      obstack_blank (&objfile->symbol_obstack,
		     alloc_count * sizeof (struct minimal_symbol));
      msymbols = (struct minimal_symbol *)
	obstack_base (&objfile->symbol_obstack);

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

      if (objfile->minimal_symbol_count)
	memcpy ((char *) msymbols, (char *) objfile->msymbols,
	    objfile->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 = objfile->minimal_symbol_count;
      leading_char = get_symbol_leading_char (objfile->obfd);

      for (bunch = msym_bunch; bunch != NULL; bunch = bunch->next)
	{
	  for (bindex = 0; bindex < msym_bunch_index; bindex++, mcount++)
	    {
	      msymbols[mcount] = bunch->contents[bindex];
	      SYMBOL_LANGUAGE (&msymbols[mcount]) = language_auto;
	      if (SYMBOL_NAME (&msymbols[mcount])[0] == leading_char)
		{
		  SYMBOL_NAME (&msymbols[mcount])++;
		}
	    }
	  msym_bunch_index = BUNCH_SIZE;
	}

      /* Sort the minimal symbols by address.  */

      qsort (msymbols, mcount, sizeof (struct minimal_symbol),
	     compare_minimal_symbols);

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

      mcount = compact_minimal_symbols (msymbols, mcount, objfile);

      obstack_blank (&objfile->symbol_obstack,
	       (mcount + 1 - alloc_count) * sizeof (struct minimal_symbol));
      msymbols = (struct minimal_symbol *)
	obstack_finish (&objfile->symbol_obstack);

      /* We also terminate the minimal symbol table with a "null symbol",
         which is *not* included in the size of the table.  This makes it
         easier to find the end of the table when we are handed a pointer
         to some symbol in the middle of it.  Zero out the fields in the
         "null symbol" allocated at the end of the array.  Note that the
         symbol count does *not* include this null symbol, which is why it
         is indexed by mcount and not mcount-1. */

      SYMBOL_NAME (&msymbols[mcount]) = NULL;
      SYMBOL_VALUE_ADDRESS (&msymbols[mcount]) = 0;
      MSYMBOL_INFO (&msymbols[mcount]) = NULL;
      MSYMBOL_TYPE (&msymbols[mcount]) = mst_unknown;
      SYMBOL_INIT_LANGUAGE_SPECIFIC (&msymbols[mcount], language_unknown);

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

      objfile->minimal_symbol_count = mcount;
      objfile->msymbols = msymbols;

      /* Try to guess the appropriate C++ ABI by looking at the names 
	 of the minimal symbols in the table.  */
      {
	int i;

	for (i = 0; i < mcount; i++)
	  {
	    const char *name = SYMBOL_NAME (&objfile->msymbols[i]);
	    if (name[0] == '_' && name[1] == 'Z')
	      {
		switch_to_cp_abi ("gnu-v3");
		break;
	      }
	  }
      }
      
      /* Now walk through all the minimal symbols, selecting the newly added
         ones and attempting to cache their C++ demangled names. */
      for (; mcount-- > 0; msymbols++)
	SYMBOL_INIT_DEMANGLED_NAME (msymbols, &objfile->symbol_obstack);

      /* Now build the hash tables; we can't do this incrementally
         at an earlier point since we weren't finished with the obstack
	 yet.  (And if the msymbol obstack gets moved, all the internal
	 pointers to other msymbols need to be adjusted.) */
      build_minimal_symbol_hash_tables (objfile);
    }
}

/* Sort all the minimal symbols in OBJFILE.  */

void
msymbols_sort (struct objfile *objfile)
{
  qsort (objfile->msymbols, objfile->minimal_symbol_count,
	 sizeof (struct minimal_symbol), compare_minimal_symbols);
  build_minimal_symbol_hash_tables (objfile);
}

/* 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.  */

struct minimal_symbol *
lookup_solib_trampoline_symbol_by_pc (CORE_ADDR pc)
{
  struct minimal_symbol *msymbol = lookup_minimal_symbol_by_pc (pc);

  if (msymbol != NULL && MSYMBOL_TYPE (msymbol) == mst_solib_trampoline)
    return msymbol;
  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 (CORE_ADDR pc)
{
  struct objfile *objfile;
  struct minimal_symbol *msymbol;
  struct minimal_symbol *tsymbol = lookup_solib_trampoline_symbol_by_pc (pc);

  if (tsymbol != NULL)
    {
      ALL_MSYMBOLS (objfile, msymbol)
      {
	if (MSYMBOL_TYPE (msymbol) == mst_text
	    && STREQ (SYMBOL_NAME (msymbol), SYMBOL_NAME (tsymbol)))
	  return SYMBOL_VALUE_ADDRESS (msymbol);
      }
    }
  return 0;
}