aboutsummaryrefslogtreecommitdiff
path: root/gdb/dwarf2expr.c
blob: 2e500e94baa0bb61da326c6cada5eb1ce33fcf61 (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
/* DWARF 2 Expression Evaluator.

   Copyright (C) 2001-2015 Free Software Foundation, Inc.

   Contributed by Daniel Berlin (dan@dberlin.org)

   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/>.  */

#include "defs.h"
#include "symtab.h"
#include "gdbtypes.h"
#include "value.h"
#include "gdbcore.h"
#include "dwarf2.h"
#include "dwarf2expr.h"
#include "dwarf2loc.h"

/* Local prototypes.  */

static void execute_stack_op (struct dwarf_expr_context *,
			      const gdb_byte *, const gdb_byte *);

/* Cookie for gdbarch data.  */

static struct gdbarch_data *dwarf_arch_cookie;

/* This holds gdbarch-specific types used by the DWARF expression
   evaluator.  See comments in execute_stack_op.  */

struct dwarf_gdbarch_types
{
  struct type *dw_types[3];
};

/* Allocate and fill in dwarf_gdbarch_types for an arch.  */

static void *
dwarf_gdbarch_types_init (struct gdbarch *gdbarch)
{
  struct dwarf_gdbarch_types *types
    = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct dwarf_gdbarch_types);

  /* The types themselves are lazily initialized.  */

  return types;
}

/* Return the type used for DWARF operations where the type is
   unspecified in the DWARF spec.  Only certain sizes are
   supported.  */

static struct type *
dwarf_expr_address_type (struct dwarf_expr_context *ctx)
{
  struct dwarf_gdbarch_types *types
    = (struct dwarf_gdbarch_types *) gdbarch_data (ctx->gdbarch,
						   dwarf_arch_cookie);
  int ndx;

  if (ctx->addr_size == 2)
    ndx = 0;
  else if (ctx->addr_size == 4)
    ndx = 1;
  else if (ctx->addr_size == 8)
    ndx = 2;
  else
    error (_("Unsupported address size in DWARF expressions: %d bits"),
	   8 * ctx->addr_size);

  if (types->dw_types[ndx] == NULL)
    types->dw_types[ndx]
      = arch_integer_type (ctx->gdbarch,
			   8 * ctx->addr_size,
			   0, "<signed DWARF address type>");

  return types->dw_types[ndx];
}

/* Create a new context for the expression evaluator.  */

struct dwarf_expr_context *
new_dwarf_expr_context (void)
{
  struct dwarf_expr_context *retval;

  retval = XCNEW (struct dwarf_expr_context);
  retval->stack_len = 0;
  retval->stack_allocated = 10;
  retval->stack = XNEWVEC (struct dwarf_stack_value, retval->stack_allocated);
  retval->num_pieces = 0;
  retval->pieces = 0;
  retval->max_recursion_depth = 0x100;
  return retval;
}

/* Release the memory allocated to CTX.  */

void
free_dwarf_expr_context (struct dwarf_expr_context *ctx)
{
  xfree (ctx->stack);
  xfree (ctx->pieces);
  xfree (ctx);
}

/* Helper for make_cleanup_free_dwarf_expr_context.  */

static void
free_dwarf_expr_context_cleanup (void *arg)
{
  free_dwarf_expr_context ((struct dwarf_expr_context *) arg);
}

/* Return a cleanup that calls free_dwarf_expr_context.  */

struct cleanup *
make_cleanup_free_dwarf_expr_context (struct dwarf_expr_context *ctx)
{
  return make_cleanup (free_dwarf_expr_context_cleanup, ctx);
}

/* Expand the memory allocated to CTX's stack to contain at least
   NEED more elements than are currently used.  */

static void
dwarf_expr_grow_stack (struct dwarf_expr_context *ctx, size_t need)
{
  if (ctx->stack_len + need > ctx->stack_allocated)
    {
      size_t newlen = ctx->stack_len + need + 10;

      ctx->stack = XRESIZEVEC (struct dwarf_stack_value, ctx->stack, newlen);
      ctx->stack_allocated = newlen;
    }
}

/* Push VALUE onto CTX's stack.  */

static void
dwarf_expr_push (struct dwarf_expr_context *ctx, struct value *value,
		 int in_stack_memory)
{
  struct dwarf_stack_value *v;

  dwarf_expr_grow_stack (ctx, 1);
  v = &ctx->stack[ctx->stack_len++];
  v->value = value;
  v->in_stack_memory = in_stack_memory;
}

/* Push VALUE onto CTX's stack.  */

void
dwarf_expr_push_address (struct dwarf_expr_context *ctx, CORE_ADDR value,
			 int in_stack_memory)
{
  dwarf_expr_push (ctx,
		   value_from_ulongest (dwarf_expr_address_type (ctx), value),
		   in_stack_memory);
}

/* Pop the top item off of CTX's stack.  */

static void
dwarf_expr_pop (struct dwarf_expr_context *ctx)
{
  if (ctx->stack_len <= 0)
    error (_("dwarf expression stack underflow"));
  ctx->stack_len--;
}

/* Retrieve the N'th item on CTX's stack.  */

struct value *
dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n)
{
  if (ctx->stack_len <= n)
     error (_("Asked for position %d of stack, "
	      "stack only has %d elements on it."),
	    n, ctx->stack_len);
  return ctx->stack[ctx->stack_len - (1 + n)].value;
}

/* Require that TYPE be an integral type; throw an exception if not.  */

static void
dwarf_require_integral (struct type *type)
{
  if (TYPE_CODE (type) != TYPE_CODE_INT
      && TYPE_CODE (type) != TYPE_CODE_CHAR
      && TYPE_CODE (type) != TYPE_CODE_BOOL)
    error (_("integral type expected in DWARF expression"));
}

/* Return the unsigned form of TYPE.  TYPE is necessarily an integral
   type.  */

static struct type *
get_unsigned_type (struct gdbarch *gdbarch, struct type *type)
{
  switch (TYPE_LENGTH (type))
    {
    case 1:
      return builtin_type (gdbarch)->builtin_uint8;
    case 2:
      return builtin_type (gdbarch)->builtin_uint16;
    case 4:
      return builtin_type (gdbarch)->builtin_uint32;
    case 8:
      return builtin_type (gdbarch)->builtin_uint64;
    default:
      error (_("no unsigned variant found for type, while evaluating "
	       "DWARF expression"));
    }
}

/* Return the signed form of TYPE.  TYPE is necessarily an integral
   type.  */

static struct type *
get_signed_type (struct gdbarch *gdbarch, struct type *type)
{
  switch (TYPE_LENGTH (type))
    {
    case 1:
      return builtin_type (gdbarch)->builtin_int8;
    case 2:
      return builtin_type (gdbarch)->builtin_int16;
    case 4:
      return builtin_type (gdbarch)->builtin_int32;
    case 8:
      return builtin_type (gdbarch)->builtin_int64;
    default:
      error (_("no signed variant found for type, while evaluating "
	       "DWARF expression"));
    }
}

/* Retrieve the N'th item on CTX's stack, converted to an address.  */

CORE_ADDR
dwarf_expr_fetch_address (struct dwarf_expr_context *ctx, int n)
{
  struct value *result_val = dwarf_expr_fetch (ctx, n);
  enum bfd_endian byte_order = gdbarch_byte_order (ctx->gdbarch);
  ULONGEST result;

  dwarf_require_integral (value_type (result_val));
  result = extract_unsigned_integer (value_contents (result_val),
				     TYPE_LENGTH (value_type (result_val)),
				     byte_order);

  /* For most architectures, calling extract_unsigned_integer() alone
     is sufficient for extracting an address.  However, some
     architectures (e.g. MIPS) use signed addresses and using
     extract_unsigned_integer() will not produce a correct
     result.  Make sure we invoke gdbarch_integer_to_address()
     for those architectures which require it.  */
  if (gdbarch_integer_to_address_p (ctx->gdbarch))
    {
      gdb_byte *buf = (gdb_byte *) alloca (ctx->addr_size);
      struct type *int_type = get_unsigned_type (ctx->gdbarch,
						 value_type (result_val));

      store_unsigned_integer (buf, ctx->addr_size, byte_order, result);
      return gdbarch_integer_to_address (ctx->gdbarch, int_type, buf);
    }

  return (CORE_ADDR) result;
}

/* Retrieve the in_stack_memory flag of the N'th item on CTX's stack.  */

int
dwarf_expr_fetch_in_stack_memory (struct dwarf_expr_context *ctx, int n)
{
  if (ctx->stack_len <= n)
     error (_("Asked for position %d of stack, "
	      "stack only has %d elements on it."),
	    n, ctx->stack_len);
  return ctx->stack[ctx->stack_len - (1 + n)].in_stack_memory;
}

/* Return true if the expression stack is empty.  */

static int
dwarf_expr_stack_empty_p (struct dwarf_expr_context *ctx)
{
  return ctx->stack_len == 0;
}

/* Add a new piece to CTX's piece list.  */
static void
add_piece (struct dwarf_expr_context *ctx, ULONGEST size, ULONGEST offset)
{
  struct dwarf_expr_piece *p;

  ctx->num_pieces++;

  ctx->pieces
    = XRESIZEVEC (struct dwarf_expr_piece, ctx->pieces, ctx->num_pieces);

  p = &ctx->pieces[ctx->num_pieces - 1];
  p->location = ctx->location;
  p->size = size;
  p->offset = offset;

  if (p->location == DWARF_VALUE_LITERAL)
    {
      p->v.literal.data = ctx->data;
      p->v.literal.length = ctx->len;
    }
  else if (dwarf_expr_stack_empty_p (ctx))
    {
      p->location = DWARF_VALUE_OPTIMIZED_OUT;
      /* Also reset the context's location, for our callers.  This is
	 a somewhat strange approach, but this lets us avoid setting
	 the location to DWARF_VALUE_MEMORY in all the individual
	 cases in the evaluator.  */
      ctx->location = DWARF_VALUE_OPTIMIZED_OUT;
    }
  else if (p->location == DWARF_VALUE_MEMORY)
    {
      p->v.mem.addr = dwarf_expr_fetch_address (ctx, 0);
      p->v.mem.in_stack_memory = dwarf_expr_fetch_in_stack_memory (ctx, 0);
    }
  else if (p->location == DWARF_VALUE_IMPLICIT_POINTER)
    {
      p->v.ptr.die.sect_off = ctx->len;
      p->v.ptr.offset = value_as_long (dwarf_expr_fetch (ctx, 0));
    }
  else if (p->location == DWARF_VALUE_REGISTER)
    p->v.regno = value_as_long (dwarf_expr_fetch (ctx, 0));
  else
    {
      p->v.value = dwarf_expr_fetch (ctx, 0);
    }
}

/* Evaluate the expression at ADDR (LEN bytes long) using the context
   CTX.  */

void
dwarf_expr_eval (struct dwarf_expr_context *ctx, const gdb_byte *addr,
		 size_t len)
{
  int old_recursion_depth = ctx->recursion_depth;

  execute_stack_op (ctx, addr, addr + len);

  /* CTX RECURSION_DEPTH becomes invalid if an exception was thrown here.  */

  gdb_assert (ctx->recursion_depth == old_recursion_depth);
}

/* Helper to read a uleb128 value or throw an error.  */

const gdb_byte *
safe_read_uleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
		   uint64_t *r)
{
  buf = gdb_read_uleb128 (buf, buf_end, r);
  if (buf == NULL)
    error (_("DWARF expression error: ran off end of buffer reading uleb128 value"));
  return buf;
}

/* Helper to read a sleb128 value or throw an error.  */

const gdb_byte *
safe_read_sleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
		   int64_t *r)
{
  buf = gdb_read_sleb128 (buf, buf_end, r);
  if (buf == NULL)
    error (_("DWARF expression error: ran off end of buffer reading sleb128 value"));
  return buf;
}

const gdb_byte *
safe_skip_leb128 (const gdb_byte *buf, const gdb_byte *buf_end)
{
  buf = gdb_skip_leb128 (buf, buf_end);
  if (buf == NULL)
    error (_("DWARF expression error: ran off end of buffer reading leb128 value"));
  return buf;
}


/* Check that the current operator is either at the end of an
   expression, or that it is followed by a composition operator.  */

void
dwarf_expr_require_composition (const gdb_byte *op_ptr, const gdb_byte *op_end,
				const char *op_name)
{
  /* It seems like DW_OP_GNU_uninit should be handled here.  However,
     it doesn't seem to make sense for DW_OP_*_value, and it was not
     checked at the other place that this function is called.  */
  if (op_ptr != op_end && *op_ptr != DW_OP_piece && *op_ptr != DW_OP_bit_piece)
    error (_("DWARF-2 expression error: `%s' operations must be "
	     "used either alone or in conjunction with DW_OP_piece "
	     "or DW_OP_bit_piece."),
	   op_name);
}

/* Return true iff the types T1 and T2 are "the same".  This only does
   checks that might reasonably be needed to compare DWARF base
   types.  */

static int
base_types_equal_p (struct type *t1, struct type *t2)
{
  if (TYPE_CODE (t1) != TYPE_CODE (t2))
    return 0;
  if (TYPE_UNSIGNED (t1) != TYPE_UNSIGNED (t2))
    return 0;
  return TYPE_LENGTH (t1) == TYPE_LENGTH (t2);
}

/* A convenience function to call get_base_type on CTX and return the
   result.  DIE is the DIE whose type we need.  SIZE is non-zero if
   this function should verify that the resulting type has the correct
   size.  */

static struct type *
dwarf_get_base_type (struct dwarf_expr_context *ctx, cu_offset die, int size)
{
  struct type *result;

  if (ctx->funcs->get_base_type)
    {
      result = ctx->funcs->get_base_type (ctx, die);
      if (result == NULL)
	error (_("Could not find type for DW_OP_GNU_const_type"));
      if (size != 0 && TYPE_LENGTH (result) != size)
	error (_("DW_OP_GNU_const_type has different sizes for type and data"));
    }
  else
    /* Anything will do.  */
    result = builtin_type (ctx->gdbarch)->builtin_int;

  return result;
}

/* If <BUF..BUF_END] contains DW_FORM_block* with single DW_OP_reg* return the
   DWARF register number.  Otherwise return -1.  */

int
dwarf_block_to_dwarf_reg (const gdb_byte *buf, const gdb_byte *buf_end)
{
  uint64_t dwarf_reg;

  if (buf_end <= buf)
    return -1;
  if (*buf >= DW_OP_reg0 && *buf <= DW_OP_reg31)
    {
      if (buf_end - buf != 1)
	return -1;
      return *buf - DW_OP_reg0;
    }

  if (*buf == DW_OP_GNU_regval_type)
    {
      buf++;
      buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
      if (buf == NULL)
	return -1;
      buf = gdb_skip_leb128 (buf, buf_end);
      if (buf == NULL)
	return -1;
    }
  else if (*buf == DW_OP_regx)
    {
      buf++;
      buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
      if (buf == NULL)
	return -1;
    }
  else
    return -1;
  if (buf != buf_end || (int) dwarf_reg != dwarf_reg)
    return -1;
  return dwarf_reg;
}

/* If <BUF..BUF_END] contains DW_FORM_block* with just DW_OP_breg*(0) and
   DW_OP_deref* return the DWARF register number.  Otherwise return -1.
   DEREF_SIZE_RETURN contains -1 for DW_OP_deref; otherwise it contains the
   size from DW_OP_deref_size.  */

int
dwarf_block_to_dwarf_reg_deref (const gdb_byte *buf, const gdb_byte *buf_end,
				CORE_ADDR *deref_size_return)
{
  uint64_t dwarf_reg;
  int64_t offset;

  if (buf_end <= buf)
    return -1;

  if (*buf >= DW_OP_breg0 && *buf <= DW_OP_breg31)
    {
      dwarf_reg = *buf - DW_OP_breg0;
      buf++;
      if (buf >= buf_end)
	return -1;
    }
  else if (*buf == DW_OP_bregx)
    {
      buf++;
      buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
      if (buf == NULL)
	return -1;
      if ((int) dwarf_reg != dwarf_reg)
       return -1;
    }
  else
    return -1;

  buf = gdb_read_sleb128 (buf, buf_end, &offset);
  if (buf == NULL)
    return -1;
  if (offset != 0)
    return -1;

  if (*buf == DW_OP_deref)
    {
      buf++;
      *deref_size_return = -1;
    }
  else if (*buf == DW_OP_deref_size)
    {
      buf++;
      if (buf >= buf_end)
       return -1;
      *deref_size_return = *buf++;
    }
  else
    return -1;

  if (buf != buf_end)
    return -1;

  return dwarf_reg;
}

/* If <BUF..BUF_END] contains DW_FORM_block* with single DW_OP_fbreg(X) fill
   in FB_OFFSET_RETURN with the X offset and return 1.  Otherwise return 0.  */

int
dwarf_block_to_fb_offset (const gdb_byte *buf, const gdb_byte *buf_end,
			  CORE_ADDR *fb_offset_return)
{
  int64_t fb_offset;

  if (buf_end <= buf)
    return 0;

  if (*buf != DW_OP_fbreg)
    return 0;
  buf++;

  buf = gdb_read_sleb128 (buf, buf_end, &fb_offset);
  if (buf == NULL)
    return 0;
  *fb_offset_return = fb_offset;
  if (buf != buf_end || fb_offset != (LONGEST) *fb_offset_return)
    return 0;

  return 1;
}

/* If <BUF..BUF_END] contains DW_FORM_block* with single DW_OP_bregSP(X) fill
   in SP_OFFSET_RETURN with the X offset and return 1.  Otherwise return 0.
   The matched SP register number depends on GDBARCH.  */

int
dwarf_block_to_sp_offset (struct gdbarch *gdbarch, const gdb_byte *buf,
			  const gdb_byte *buf_end, CORE_ADDR *sp_offset_return)
{
  uint64_t dwarf_reg;
  int64_t sp_offset;

  if (buf_end <= buf)
    return 0;
  if (*buf >= DW_OP_breg0 && *buf <= DW_OP_breg31)
    {
      dwarf_reg = *buf - DW_OP_breg0;
      buf++;
    }
  else
    {
      if (*buf != DW_OP_bregx)
       return 0;
      buf++;
      buf = gdb_read_uleb128 (buf, buf_end, &dwarf_reg);
      if (buf == NULL)
	return 0;
    }

  if (dwarf_reg_to_regnum (gdbarch, dwarf_reg)
      != gdbarch_sp_regnum (gdbarch))
    return 0;

  buf = gdb_read_sleb128 (buf, buf_end, &sp_offset);
  if (buf == NULL)
    return 0;
  *sp_offset_return = sp_offset;
  if (buf != buf_end || sp_offset != (LONGEST) *sp_offset_return)
    return 0;

  return 1;
}

/* The engine for the expression evaluator.  Using the context in CTX,
   evaluate the expression between OP_PTR and OP_END.  */

static void
execute_stack_op (struct dwarf_expr_context *ctx,
		  const gdb_byte *op_ptr, const gdb_byte *op_end)
{
  enum bfd_endian byte_order = gdbarch_byte_order (ctx->gdbarch);
  /* Old-style "untyped" DWARF values need special treatment in a
     couple of places, specifically DW_OP_mod and DW_OP_shr.  We need
     a special type for these values so we can distinguish them from
     values that have an explicit type, because explicitly-typed
     values do not need special treatment.  This special type must be
     different (in the `==' sense) from any base type coming from the
     CU.  */
  struct type *address_type = dwarf_expr_address_type (ctx);

  ctx->location = DWARF_VALUE_MEMORY;
  ctx->initialized = 1;  /* Default is initialized.  */

  if (ctx->recursion_depth > ctx->max_recursion_depth)
    error (_("DWARF-2 expression error: Loop detected (%d)."),
	   ctx->recursion_depth);
  ctx->recursion_depth++;

  while (op_ptr < op_end)
    {
      enum dwarf_location_atom op = (enum dwarf_location_atom) *op_ptr++;
      ULONGEST result;
      /* Assume the value is not in stack memory.
	 Code that knows otherwise sets this to 1.
	 Some arithmetic on stack addresses can probably be assumed to still
	 be a stack address, but we skip this complication for now.
	 This is just an optimization, so it's always ok to punt
	 and leave this as 0.  */
      int in_stack_memory = 0;
      uint64_t uoffset, reg;
      int64_t offset;
      struct value *result_val = NULL;

      /* The DWARF expression might have a bug causing an infinite
	 loop.  In that case, quitting is the only way out.  */
      QUIT;

      switch (op)
	{
	case DW_OP_lit0:
	case DW_OP_lit1:
	case DW_OP_lit2:
	case DW_OP_lit3:
	case DW_OP_lit4:
	case DW_OP_lit5:
	case DW_OP_lit6:
	case DW_OP_lit7:
	case DW_OP_lit8:
	case DW_OP_lit9:
	case DW_OP_lit10:
	case DW_OP_lit11:
	case DW_OP_lit12:
	case DW_OP_lit13:
	case DW_OP_lit14:
	case DW_OP_lit15:
	case DW_OP_lit16:
	case DW_OP_lit17:
	case DW_OP_lit18:
	case DW_OP_lit19:
	case DW_OP_lit20:
	case DW_OP_lit21:
	case DW_OP_lit22:
	case DW_OP_lit23:
	case DW_OP_lit24:
	case DW_OP_lit25:
	case DW_OP_lit26:
	case DW_OP_lit27:
	case DW_OP_lit28:
	case DW_OP_lit29:
	case DW_OP_lit30:
	case DW_OP_lit31:
	  result = op - DW_OP_lit0;
	  result_val = value_from_ulongest (address_type, result);
	  break;

	case DW_OP_addr:
	  result = extract_unsigned_integer (op_ptr,
					     ctx->addr_size, byte_order);
	  op_ptr += ctx->addr_size;
	  /* Some versions of GCC emit DW_OP_addr before
	     DW_OP_GNU_push_tls_address.  In this case the value is an
	     index, not an address.  We don't support things like
	     branching between the address and the TLS op.  */
	  if (op_ptr >= op_end || *op_ptr != DW_OP_GNU_push_tls_address)
	    result += ctx->offset;
	  result_val = value_from_ulongest (address_type, result);
	  break;

	case DW_OP_GNU_addr_index:
	  op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
	  result = (ctx->funcs->get_addr_index) (ctx->baton, uoffset);
	  result += ctx->offset;
	  result_val = value_from_ulongest (address_type, result);
	  break;
	case DW_OP_GNU_const_index:
	  op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
	  result = (ctx->funcs->get_addr_index) (ctx->baton, uoffset);
	  result_val = value_from_ulongest (address_type, result);
	  break;

	case DW_OP_const1u:
	  result = extract_unsigned_integer (op_ptr, 1, byte_order);
	  result_val = value_from_ulongest (address_type, result);
	  op_ptr += 1;
	  break;
	case DW_OP_const1s:
	  result = extract_signed_integer (op_ptr, 1, byte_order);
	  result_val = value_from_ulongest (address_type, result);
	  op_ptr += 1;
	  break;
	case DW_OP_const2u:
	  result = extract_unsigned_integer (op_ptr, 2, byte_order);
	  result_val = value_from_ulongest (address_type, result);
	  op_ptr += 2;
	  break;
	case DW_OP_const2s:
	  result = extract_signed_integer (op_ptr, 2, byte_order);
	  result_val = value_from_ulongest (address_type, result);
	  op_ptr += 2;
	  break;
	case DW_OP_const4u:
	  result = extract_unsigned_integer (op_ptr, 4, byte_order);
	  result_val = value_from_ulongest (address_type, result);
	  op_ptr += 4;
	  break;
	case DW_OP_const4s:
	  result = extract_signed_integer (op_ptr, 4, byte_order);
	  result_val = value_from_ulongest (address_type, result);
	  op_ptr += 4;
	  break;
	case DW_OP_const8u:
	  result = extract_unsigned_integer (op_ptr, 8, byte_order);
	  result_val = value_from_ulongest (address_type, result);
	  op_ptr += 8;
	  break;
	case DW_OP_const8s:
	  result = extract_signed_integer (op_ptr, 8, byte_order);
	  result_val = value_from_ulongest (address_type, result);
	  op_ptr += 8;
	  break;
	case DW_OP_constu:
	  op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
	  result = uoffset;
	  result_val = value_from_ulongest (address_type, result);
	  break;
	case DW_OP_consts:
	  op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
	  result = offset;
	  result_val = value_from_ulongest (address_type, result);
	  break;

	/* The DW_OP_reg operations are required to occur alone in
	   location expressions.  */
	case DW_OP_reg0:
	case DW_OP_reg1:
	case DW_OP_reg2:
	case DW_OP_reg3:
	case DW_OP_reg4:
	case DW_OP_reg5:
	case DW_OP_reg6:
	case DW_OP_reg7:
	case DW_OP_reg8:
	case DW_OP_reg9:
	case DW_OP_reg10:
	case DW_OP_reg11:
	case DW_OP_reg12:
	case DW_OP_reg13:
	case DW_OP_reg14:
	case DW_OP_reg15:
	case DW_OP_reg16:
	case DW_OP_reg17:
	case DW_OP_reg18:
	case DW_OP_reg19:
	case DW_OP_reg20:
	case DW_OP_reg21:
	case DW_OP_reg22:
	case DW_OP_reg23:
	case DW_OP_reg24:
	case DW_OP_reg25:
	case DW_OP_reg26:
	case DW_OP_reg27:
	case DW_OP_reg28:
	case DW_OP_reg29:
	case DW_OP_reg30:
	case DW_OP_reg31:
	  if (op_ptr != op_end 
	      && *op_ptr != DW_OP_piece
	      && *op_ptr != DW_OP_bit_piece
	      && *op_ptr != DW_OP_GNU_uninit)
	    error (_("DWARF-2 expression error: DW_OP_reg operations must be "
		     "used either alone or in conjunction with DW_OP_piece "
		     "or DW_OP_bit_piece."));

	  result = op - DW_OP_reg0;
	  result_val = value_from_ulongest (address_type, result);
	  ctx->location = DWARF_VALUE_REGISTER;
	  break;

	case DW_OP_regx:
	  op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
	  dwarf_expr_require_composition (op_ptr, op_end, "DW_OP_regx");

	  result = reg;
	  result_val = value_from_ulongest (address_type, result);
	  ctx->location = DWARF_VALUE_REGISTER;
	  break;

	case DW_OP_implicit_value:
	  {
	    uint64_t len;

	    op_ptr = safe_read_uleb128 (op_ptr, op_end, &len);
	    if (op_ptr + len > op_end)
	      error (_("DW_OP_implicit_value: too few bytes available."));
	    ctx->len = len;
	    ctx->data = op_ptr;
	    ctx->location = DWARF_VALUE_LITERAL;
	    op_ptr += len;
	    dwarf_expr_require_composition (op_ptr, op_end,
					    "DW_OP_implicit_value");
	  }
	  goto no_push;

	case DW_OP_stack_value:
	  ctx->location = DWARF_VALUE_STACK;
	  dwarf_expr_require_composition (op_ptr, op_end, "DW_OP_stack_value");
	  goto no_push;

	case DW_OP_GNU_implicit_pointer:
	  {
	    int64_t len;

	    if (ctx->ref_addr_size == -1)
	      error (_("DWARF-2 expression error: DW_OP_GNU_implicit_pointer "
		       "is not allowed in frame context"));

	    /* The referred-to DIE of sect_offset kind.  */
	    ctx->len = extract_unsigned_integer (op_ptr, ctx->ref_addr_size,
						 byte_order);
	    op_ptr += ctx->ref_addr_size;

	    /* The byte offset into the data.  */
	    op_ptr = safe_read_sleb128 (op_ptr, op_end, &len);
	    result = (ULONGEST) len;
	    result_val = value_from_ulongest (address_type, result);

	    ctx->location = DWARF_VALUE_IMPLICIT_POINTER;
	    dwarf_expr_require_composition (op_ptr, op_end,
					    "DW_OP_GNU_implicit_pointer");
	  }
	  break;

	case DW_OP_breg0:
	case DW_OP_breg1:
	case DW_OP_breg2:
	case DW_OP_breg3:
	case DW_OP_breg4:
	case DW_OP_breg5:
	case DW_OP_breg6:
	case DW_OP_breg7:
	case DW_OP_breg8:
	case DW_OP_breg9:
	case DW_OP_breg10:
	case DW_OP_breg11:
	case DW_OP_breg12:
	case DW_OP_breg13:
	case DW_OP_breg14:
	case DW_OP_breg15:
	case DW_OP_breg16:
	case DW_OP_breg17:
	case DW_OP_breg18:
	case DW_OP_breg19:
	case DW_OP_breg20:
	case DW_OP_breg21:
	case DW_OP_breg22:
	case DW_OP_breg23:
	case DW_OP_breg24:
	case DW_OP_breg25:
	case DW_OP_breg26:
	case DW_OP_breg27:
	case DW_OP_breg28:
	case DW_OP_breg29:
	case DW_OP_breg30:
	case DW_OP_breg31:
	  {
	    op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
	    result = (ctx->funcs->read_addr_from_reg) (ctx->baton,
						       op - DW_OP_breg0);
	    result += offset;
	    result_val = value_from_ulongest (address_type, result);
	  }
	  break;
	case DW_OP_bregx:
	  {
	    op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
	    op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
	    result = (ctx->funcs->read_addr_from_reg) (ctx->baton, reg);
	    result += offset;
	    result_val = value_from_ulongest (address_type, result);
	  }
	  break;
	case DW_OP_fbreg:
	  {
	    const gdb_byte *datastart;
	    size_t datalen;
	    unsigned int before_stack_len;

	    op_ptr = safe_read_sleb128 (op_ptr, op_end, &offset);
	    /* Rather than create a whole new context, we simply
	       record the stack length before execution, then reset it
	       afterwards, effectively erasing whatever the recursive
	       call put there.  */
	    before_stack_len = ctx->stack_len;
	    /* FIXME: cagney/2003-03-26: This code should be using
               get_frame_base_address(), and then implement a dwarf2
               specific this_base method.  */
	    (ctx->funcs->get_frame_base) (ctx->baton, &datastart, &datalen);
	    dwarf_expr_eval (ctx, datastart, datalen);
	    if (ctx->location == DWARF_VALUE_MEMORY)
	      result = dwarf_expr_fetch_address (ctx, 0);
	    else if (ctx->location == DWARF_VALUE_REGISTER)
	      result = (ctx->funcs->read_addr_from_reg)
			  (ctx->baton,
			   value_as_long (dwarf_expr_fetch (ctx, 0)));
	    else
	      error (_("Not implemented: computing frame "
		       "base using explicit value operator"));
	    result = result + offset;
	    result_val = value_from_ulongest (address_type, result);
	    in_stack_memory = 1;
	    ctx->stack_len = before_stack_len;
	    ctx->location = DWARF_VALUE_MEMORY;
	  }
	  break;

	case DW_OP_dup:
	  result_val = dwarf_expr_fetch (ctx, 0);
	  in_stack_memory = dwarf_expr_fetch_in_stack_memory (ctx, 0);
	  break;

	case DW_OP_drop:
	  dwarf_expr_pop (ctx);
	  goto no_push;

	case DW_OP_pick:
	  offset = *op_ptr++;
	  result_val = dwarf_expr_fetch (ctx, offset);
	  in_stack_memory = dwarf_expr_fetch_in_stack_memory (ctx, offset);
	  break;
	  
	case DW_OP_swap:
	  {
	    struct dwarf_stack_value t1, t2;

	    if (ctx->stack_len < 2)
	       error (_("Not enough elements for "
			"DW_OP_swap.  Need 2, have %d."),
		      ctx->stack_len);
	    t1 = ctx->stack[ctx->stack_len - 1];
	    t2 = ctx->stack[ctx->stack_len - 2];
	    ctx->stack[ctx->stack_len - 1] = t2;
	    ctx->stack[ctx->stack_len - 2] = t1;
	    goto no_push;
	  }

	case DW_OP_over:
	  result_val = dwarf_expr_fetch (ctx, 1);
	  in_stack_memory = dwarf_expr_fetch_in_stack_memory (ctx, 1);
	  break;

	case DW_OP_rot:
	  {
	    struct dwarf_stack_value t1, t2, t3;

	    if (ctx->stack_len < 3)
	       error (_("Not enough elements for "
			"DW_OP_rot.  Need 3, have %d."),
		      ctx->stack_len);
	    t1 = ctx->stack[ctx->stack_len - 1];
	    t2 = ctx->stack[ctx->stack_len - 2];
	    t3 = ctx->stack[ctx->stack_len - 3];
	    ctx->stack[ctx->stack_len - 1] = t2;
	    ctx->stack[ctx->stack_len - 2] = t3;
	    ctx->stack[ctx->stack_len - 3] = t1;
	    goto no_push;
	  }

	case DW_OP_deref:
	case DW_OP_deref_size:
	case DW_OP_GNU_deref_type:
	  {
	    int addr_size = (op == DW_OP_deref ? ctx->addr_size : *op_ptr++);
	    gdb_byte *buf = (gdb_byte *) alloca (addr_size);
	    CORE_ADDR addr = dwarf_expr_fetch_address (ctx, 0);
	    struct type *type;

	    dwarf_expr_pop (ctx);

	    if (op == DW_OP_GNU_deref_type)
	      {
		cu_offset type_die;

		op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
		type_die.cu_off = uoffset;
		type = dwarf_get_base_type (ctx, type_die, 0);
	      }
	    else
	      type = address_type;

	    (ctx->funcs->read_mem) (ctx->baton, buf, addr, addr_size);

	    /* If the size of the object read from memory is different
	       from the type length, we need to zero-extend it.  */
	    if (TYPE_LENGTH (type) != addr_size)
	      {
		ULONGEST result =
		  extract_unsigned_integer (buf, addr_size, byte_order);

		buf = (gdb_byte *) alloca (TYPE_LENGTH (type));
		store_unsigned_integer (buf, TYPE_LENGTH (type),
					byte_order, result);
	      }

	    result_val = value_from_contents_and_address (type, buf, addr);
	    break;
	  }

	case DW_OP_abs:
	case DW_OP_neg:
	case DW_OP_not:
	case DW_OP_plus_uconst:
	  {
	    /* Unary operations.  */
	    result_val = dwarf_expr_fetch (ctx, 0);
	    dwarf_expr_pop (ctx);

	    switch (op)
	      {
	      case DW_OP_abs:
		if (value_less (result_val,
				value_zero (value_type (result_val), not_lval)))
		  result_val = value_neg (result_val);
		break;
	      case DW_OP_neg:
		result_val = value_neg (result_val);
		break;
	      case DW_OP_not:
		dwarf_require_integral (value_type (result_val));
		result_val = value_complement (result_val);
		break;
	      case DW_OP_plus_uconst:
		dwarf_require_integral (value_type (result_val));
		result = value_as_long (result_val);
		op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
		result += reg;
		result_val = value_from_ulongest (address_type, result);
		break;
	      }
	  }
	  break;

	case DW_OP_and:
	case DW_OP_div:
	case DW_OP_minus:
	case DW_OP_mod:
	case DW_OP_mul:
	case DW_OP_or:
	case DW_OP_plus:
	case DW_OP_shl:
	case DW_OP_shr:
	case DW_OP_shra:
	case DW_OP_xor:
	case DW_OP_le:
	case DW_OP_ge:
	case DW_OP_eq:
	case DW_OP_lt:
	case DW_OP_gt:
	case DW_OP_ne:
	  {
	    /* Binary operations.  */
	    struct value *first, *second;

	    second = dwarf_expr_fetch (ctx, 0);
	    dwarf_expr_pop (ctx);

	    first = dwarf_expr_fetch (ctx, 0);
	    dwarf_expr_pop (ctx);

	    if (! base_types_equal_p (value_type (first), value_type (second)))
	      error (_("Incompatible types on DWARF stack"));

	    switch (op)
	      {
	      case DW_OP_and:
		dwarf_require_integral (value_type (first));
		dwarf_require_integral (value_type (second));
		result_val = value_binop (first, second, BINOP_BITWISE_AND);
		break;
	      case DW_OP_div:
		result_val = value_binop (first, second, BINOP_DIV);
                break;
	      case DW_OP_minus:
		result_val = value_binop (first, second, BINOP_SUB);
		break;
	      case DW_OP_mod:
		{
		  int cast_back = 0;
		  struct type *orig_type = value_type (first);

		  /* We have to special-case "old-style" untyped values
		     -- these must have mod computed using unsigned
		     math.  */
		  if (orig_type == address_type)
		    {
		      struct type *utype
			= get_unsigned_type (ctx->gdbarch, orig_type);

		      cast_back = 1;
		      first = value_cast (utype, first);
		      second = value_cast (utype, second);
		    }
		  /* Note that value_binop doesn't handle float or
		     decimal float here.  This seems unimportant.  */
		  result_val = value_binop (first, second, BINOP_MOD);
		  if (cast_back)
		    result_val = value_cast (orig_type, result_val);
		}
		break;
	      case DW_OP_mul:
		result_val = value_binop (first, second, BINOP_MUL);
		break;
	      case DW_OP_or:
		dwarf_require_integral (value_type (first));
		dwarf_require_integral (value_type (second));
		result_val = value_binop (first, second, BINOP_BITWISE_IOR);
		break;
	      case DW_OP_plus:
		result_val = value_binop (first, second, BINOP_ADD);
		break;
	      case DW_OP_shl:
		dwarf_require_integral (value_type (first));
		dwarf_require_integral (value_type (second));
		result_val = value_binop (first, second, BINOP_LSH);
		break;
	      case DW_OP_shr:
		dwarf_require_integral (value_type (first));
		dwarf_require_integral (value_type (second));
		if (!TYPE_UNSIGNED (value_type (first)))
		  {
		    struct type *utype
		      = get_unsigned_type (ctx->gdbarch, value_type (first));

		    first = value_cast (utype, first);
		  }

		result_val = value_binop (first, second, BINOP_RSH);
		/* Make sure we wind up with the same type we started
		   with.  */
		if (value_type (result_val) != value_type (second))
		  result_val = value_cast (value_type (second), result_val);
                break;
	      case DW_OP_shra:
		dwarf_require_integral (value_type (first));
		dwarf_require_integral (value_type (second));
		if (TYPE_UNSIGNED (value_type (first)))
		  {
		    struct type *stype
		      = get_signed_type (ctx->gdbarch, value_type (first));

		    first = value_cast (stype, first);
		  }

		result_val = value_binop (first, second, BINOP_RSH);
		/* Make sure we wind up with the same type we started
		   with.  */
		if (value_type (result_val) != value_type (second))
		  result_val = value_cast (value_type (second), result_val);
		break;
	      case DW_OP_xor:
		dwarf_require_integral (value_type (first));
		dwarf_require_integral (value_type (second));
		result_val = value_binop (first, second, BINOP_BITWISE_XOR);
		break;
	      case DW_OP_le:
		/* A <= B is !(B < A).  */
		result = ! value_less (second, first);
		result_val = value_from_ulongest (address_type, result);
		break;
	      case DW_OP_ge:
		/* A >= B is !(A < B).  */
		result = ! value_less (first, second);
		result_val = value_from_ulongest (address_type, result);
		break;
	      case DW_OP_eq:
		result = value_equal (first, second);
		result_val = value_from_ulongest (address_type, result);
		break;
	      case DW_OP_lt:
		result = value_less (first, second);
		result_val = value_from_ulongest (address_type, result);
		break;
	      case DW_OP_gt:
		/* A > B is B < A.  */
		result = value_less (second, first);
		result_val = value_from_ulongest (address_type, result);
		break;
	      case DW_OP_ne:
		result = ! value_equal (first, second);
		result_val = value_from_ulongest (address_type, result);
		break;
	      default:
		internal_error (__FILE__, __LINE__,
				_("Can't be reached."));
	      }
	  }
	  break;

	case DW_OP_call_frame_cfa:
	  result = (ctx->funcs->get_frame_cfa) (ctx->baton);
	  result_val = value_from_ulongest (address_type, result);
	  in_stack_memory = 1;
	  break;

	case DW_OP_GNU_push_tls_address:
	  /* Variable is at a constant offset in the thread-local
	  storage block into the objfile for the current thread and
	  the dynamic linker module containing this expression.  Here
	  we return returns the offset from that base.  The top of the
	  stack has the offset from the beginning of the thread
	  control block at which the variable is located.  Nothing
	  should follow this operator, so the top of stack would be
	  returned.  */
	  result = value_as_long (dwarf_expr_fetch (ctx, 0));
	  dwarf_expr_pop (ctx);
	  result = (ctx->funcs->get_tls_address) (ctx->baton, result);
	  result_val = value_from_ulongest (address_type, result);
	  break;

	case DW_OP_skip:
	  offset = extract_signed_integer (op_ptr, 2, byte_order);
	  op_ptr += 2;
	  op_ptr += offset;
	  goto no_push;

	case DW_OP_bra:
	  {
	    struct value *val;

	    offset = extract_signed_integer (op_ptr, 2, byte_order);
	    op_ptr += 2;
	    val = dwarf_expr_fetch (ctx, 0);
	    dwarf_require_integral (value_type (val));
	    if (value_as_long (val) != 0)
	      op_ptr += offset;
	    dwarf_expr_pop (ctx);
	  }
	  goto no_push;

	case DW_OP_nop:
	  goto no_push;

        case DW_OP_piece:
          {
            uint64_t size;

            /* Record the piece.  */
            op_ptr = safe_read_uleb128 (op_ptr, op_end, &size);
	    add_piece (ctx, 8 * size, 0);

            /* Pop off the address/regnum, and reset the location
	       type.  */
	    if (ctx->location != DWARF_VALUE_LITERAL
		&& ctx->location != DWARF_VALUE_OPTIMIZED_OUT)
	      dwarf_expr_pop (ctx);
            ctx->location = DWARF_VALUE_MEMORY;
          }
          goto no_push;

	case DW_OP_bit_piece:
	  {
	    uint64_t size, offset;

            /* Record the piece.  */
	    op_ptr = safe_read_uleb128 (op_ptr, op_end, &size);
	    op_ptr = safe_read_uleb128 (op_ptr, op_end, &offset);
	    add_piece (ctx, size, offset);

            /* Pop off the address/regnum, and reset the location
	       type.  */
	    if (ctx->location != DWARF_VALUE_LITERAL
		&& ctx->location != DWARF_VALUE_OPTIMIZED_OUT)
	      dwarf_expr_pop (ctx);
            ctx->location = DWARF_VALUE_MEMORY;
	  }
	  goto no_push;

	case DW_OP_GNU_uninit:
	  if (op_ptr != op_end)
	    error (_("DWARF-2 expression error: DW_OP_GNU_uninit must always "
		   "be the very last op."));

	  ctx->initialized = 0;
	  goto no_push;

	case DW_OP_call2:
	  {
	    cu_offset offset;

	    offset.cu_off = extract_unsigned_integer (op_ptr, 2, byte_order);
	    op_ptr += 2;
	    ctx->funcs->dwarf_call (ctx, offset);
	  }
	  goto no_push;

	case DW_OP_call4:
	  {
	    cu_offset offset;

	    offset.cu_off = extract_unsigned_integer (op_ptr, 4, byte_order);
	    op_ptr += 4;
	    ctx->funcs->dwarf_call (ctx, offset);
	  }
	  goto no_push;
	
	case DW_OP_GNU_entry_value:
	  {
	    uint64_t len;
	    CORE_ADDR deref_size;
	    union call_site_parameter_u kind_u;

	    op_ptr = safe_read_uleb128 (op_ptr, op_end, &len);
	    if (op_ptr + len > op_end)
	      error (_("DW_OP_GNU_entry_value: too few bytes available."));

	    kind_u.dwarf_reg = dwarf_block_to_dwarf_reg (op_ptr, op_ptr + len);
	    if (kind_u.dwarf_reg != -1)
	      {
		op_ptr += len;
		ctx->funcs->push_dwarf_reg_entry_value (ctx,
						  CALL_SITE_PARAMETER_DWARF_REG,
							kind_u,
							-1 /* deref_size */);
		goto no_push;
	      }

	    kind_u.dwarf_reg = dwarf_block_to_dwarf_reg_deref (op_ptr,
							       op_ptr + len,
							       &deref_size);
	    if (kind_u.dwarf_reg != -1)
	      {
		if (deref_size == -1)
		  deref_size = ctx->addr_size;
		op_ptr += len;
		ctx->funcs->push_dwarf_reg_entry_value (ctx,
						  CALL_SITE_PARAMETER_DWARF_REG,
							kind_u, deref_size);
		goto no_push;
	      }

	    error (_("DWARF-2 expression error: DW_OP_GNU_entry_value is "
		     "supported only for single DW_OP_reg* "
		     "or for DW_OP_breg*(0)+DW_OP_deref*"));
	  }

	case DW_OP_GNU_parameter_ref:
	  {
	    union call_site_parameter_u kind_u;

	    kind_u.param_offset.cu_off = extract_unsigned_integer (op_ptr, 4,
								   byte_order);
	    op_ptr += 4;
	    ctx->funcs->push_dwarf_reg_entry_value (ctx,
					       CALL_SITE_PARAMETER_PARAM_OFFSET,
						    kind_u,
						    -1 /* deref_size */);
	  }
	  goto no_push;

	case DW_OP_GNU_const_type:
	  {
	    cu_offset type_die;
	    int n;
	    const gdb_byte *data;
	    struct type *type;

	    op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
	    type_die.cu_off = uoffset;
	    n = *op_ptr++;
	    data = op_ptr;
	    op_ptr += n;

	    type = dwarf_get_base_type (ctx, type_die, n);
	    result_val = value_from_contents (type, data);
	  }
	  break;

	case DW_OP_GNU_regval_type:
	  {
	    cu_offset type_die;
	    struct type *type;

	    op_ptr = safe_read_uleb128 (op_ptr, op_end, &reg);
	    op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
	    type_die.cu_off = uoffset;

	    type = dwarf_get_base_type (ctx, type_die, 0);
	    result_val = ctx->funcs->get_reg_value (ctx->baton, type, reg);
	  }
	  break;

	case DW_OP_GNU_convert:
	case DW_OP_GNU_reinterpret:
	  {
	    cu_offset type_die;
	    struct type *type;

	    op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
	    type_die.cu_off = uoffset;

	    if (type_die.cu_off == 0)
	      type = address_type;
	    else
	      type = dwarf_get_base_type (ctx, type_die, 0);

	    result_val = dwarf_expr_fetch (ctx, 0);
	    dwarf_expr_pop (ctx);

	    if (op == DW_OP_GNU_convert)
	      result_val = value_cast (type, result_val);
	    else if (type == value_type (result_val))
	      {
		/* Nothing.  */
	      }
	    else if (TYPE_LENGTH (type)
		     != TYPE_LENGTH (value_type (result_val)))
	      error (_("DW_OP_GNU_reinterpret has wrong size"));
	    else
	      result_val
		= value_from_contents (type,
				       value_contents_all (result_val));
	  }
	  break;

	case DW_OP_push_object_address:
	  /* Return the address of the object we are currently observing.  */
	  result = (ctx->funcs->get_object_address) (ctx->baton);
	  result_val = value_from_ulongest (address_type, result);
	  break;

	default:
	  error (_("Unhandled dwarf expression opcode 0x%x"), op);
	}

      /* Most things push a result value.  */
      gdb_assert (result_val != NULL);
      dwarf_expr_push (ctx, result_val, in_stack_memory);
    no_push:
      ;
    }

  /* To simplify our main caller, if the result is an implicit
     pointer, then make a pieced value.  This is ok because we can't
     have implicit pointers in contexts where pieces are invalid.  */
  if (ctx->location == DWARF_VALUE_IMPLICIT_POINTER)
    add_piece (ctx, 8 * ctx->addr_size, 0);

abort_expression:
  ctx->recursion_depth--;
  gdb_assert (ctx->recursion_depth >= 0);
}

/* Stub dwarf_expr_context_funcs.get_frame_base implementation.  */

void
ctx_no_get_frame_base (void *baton, const gdb_byte **start, size_t *length)
{
  error (_("%s is invalid in this context"), "DW_OP_fbreg");
}

/* Stub dwarf_expr_context_funcs.get_frame_cfa implementation.  */

CORE_ADDR
ctx_no_get_frame_cfa (void *baton)
{
  error (_("%s is invalid in this context"), "DW_OP_call_frame_cfa");
}

/* Stub dwarf_expr_context_funcs.get_frame_pc implementation.  */

CORE_ADDR
ctx_no_get_frame_pc (void *baton)
{
  error (_("%s is invalid in this context"), "DW_OP_GNU_implicit_pointer");
}

/* Stub dwarf_expr_context_funcs.get_tls_address implementation.  */

CORE_ADDR
ctx_no_get_tls_address (void *baton, CORE_ADDR offset)
{
  error (_("%s is invalid in this context"), "DW_OP_GNU_push_tls_address");
}

/* Stub dwarf_expr_context_funcs.dwarf_call implementation.  */

void
ctx_no_dwarf_call (struct dwarf_expr_context *ctx, cu_offset die_offset)
{
  error (_("%s is invalid in this context"), "DW_OP_call*");
}

/* Stub dwarf_expr_context_funcs.get_base_type implementation.  */

struct type *
ctx_no_get_base_type (struct dwarf_expr_context *ctx, cu_offset die)
{
  error (_("Support for typed DWARF is not supported in this context"));
}

/* Stub dwarf_expr_context_funcs.push_dwarf_block_entry_value
   implementation.  */

void
ctx_no_push_dwarf_reg_entry_value (struct dwarf_expr_context *ctx,
				   enum call_site_parameter_kind kind,
				   union call_site_parameter_u kind_u,
				   int deref_size)
{
  internal_error (__FILE__, __LINE__,
		  _("Support for DW_OP_GNU_entry_value is unimplemented"));
}

/* Stub dwarf_expr_context_funcs.get_addr_index implementation.  */

CORE_ADDR
ctx_no_get_addr_index (void *baton, unsigned int index)
{
  error (_("%s is invalid in this context"), "DW_OP_GNU_addr_index");
}

/* Provide a prototype to silence -Wmissing-prototypes.  */
extern initialize_file_ftype _initialize_dwarf2expr;

void
_initialize_dwarf2expr (void)
{
  dwarf_arch_cookie
    = gdbarch_data_register_post_init (dwarf_gdbarch_types_init);
}