aboutsummaryrefslogtreecommitdiff
path: root/gdb/frv-tdep.c
blob: ca5ffe3c1a13e079a48078239724d0bb0cc4665e (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
/* Target-dependent code for the Fujitsu FR-V, for GDB, the GNU Debugger.

   Copyright (C) 2002-2020 Free Software Foundation, Inc.

   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 "inferior.h"
#include "gdbcore.h"
#include "arch-utils.h"
#include "regcache.h"
#include "frame.h"
#include "frame-unwind.h"
#include "frame-base.h"
#include "trad-frame.h"
#include "dis-asm.h"
#include "sim-regno.h"
#include "gdb/sim-frv.h"
#include "opcodes/frv-desc.h"	/* for the H_SPR_... enums */
#include "symtab.h"
#include "elf-bfd.h"
#include "elf/frv.h"
#include "osabi.h"
#include "infcall.h"
#include "solib.h"
#include "frv-tdep.h"
#include "objfiles.h"

struct frv_unwind_cache		/* was struct frame_extra_info */
  {
    /* The previous frame's inner-most stack address.  Used as this
       frame ID's stack_addr.  */
    CORE_ADDR prev_sp;

    /* The frame's base, optionally used by the high-level debug info.  */
    CORE_ADDR base;

    /* Table indicating the location of each and every register.  */
    struct trad_frame_saved_reg *saved_regs;
  };

/* A structure describing a particular variant of the FRV.
   We allocate and initialize one of these structures when we create
   the gdbarch object for a variant.

   At the moment, all the FR variants we support differ only in which
   registers are present; the portable code of GDB knows that
   registers whose names are the empty string don't exist, so the
   `register_names' array captures all the per-variant information we
   need.

   in the future, if we need to have per-variant maps for raw size,
   virtual type, etc., we should replace register_names with an array
   of structures, each of which gives all the necessary info for one
   register.  Don't stick parallel arrays in here --- that's so
   Fortran.  */
struct gdbarch_tdep
{
  /* Which ABI is in use?  */
  enum frv_abi frv_abi;

  /* How many general-purpose registers does this variant have?  */
  int num_gprs;

  /* How many floating-point registers does this variant have?  */
  int num_fprs;

  /* How many hardware watchpoints can it support?  */
  int num_hw_watchpoints;

  /* How many hardware breakpoints can it support?  */
  int num_hw_breakpoints;

  /* Register names.  */
  const char **register_names;
};

/* Return the FR-V ABI associated with GDBARCH.  */
enum frv_abi
frv_abi (struct gdbarch *gdbarch)
{
  return gdbarch_tdep (gdbarch)->frv_abi;
}

/* Fetch the interpreter and executable loadmap addresses (for shared
   library support) for the FDPIC ABI.  Return 0 if successful, -1 if
   not.  (E.g, -1 will be returned if the ABI isn't the FDPIC ABI.)  */
int
frv_fdpic_loadmap_addresses (struct gdbarch *gdbarch, CORE_ADDR *interp_addr,
                             CORE_ADDR *exec_addr)
{
  if (frv_abi (gdbarch) != FRV_ABI_FDPIC)
    return -1;
  else
    {
      struct regcache *regcache = get_current_regcache ();

      if (interp_addr != NULL)
	{
	  ULONGEST val;
	  regcache_cooked_read_unsigned (regcache,
					 fdpic_loadmap_interp_regnum, &val);
	  *interp_addr = val;
	}
      if (exec_addr != NULL)
	{
	  ULONGEST val;
	  regcache_cooked_read_unsigned (regcache,
					 fdpic_loadmap_exec_regnum, &val);
	  *exec_addr = val;
	}
      return 0;
    }
}

/* Allocate a new variant structure, and set up default values for all
   the fields.  */
static struct gdbarch_tdep *
new_variant (void)
{
  struct gdbarch_tdep *var;
  int r;

  var = XCNEW (struct gdbarch_tdep);

  var->frv_abi = FRV_ABI_EABI;
  var->num_gprs = 64;
  var->num_fprs = 64;
  var->num_hw_watchpoints = 0;
  var->num_hw_breakpoints = 0;

  /* By default, don't supply any general-purpose or floating-point
     register names.  */
  var->register_names 
    = (const char **) xmalloc ((frv_num_regs + frv_num_pseudo_regs)
			       * sizeof (const char *));
  for (r = 0; r < frv_num_regs + frv_num_pseudo_regs; r++)
    var->register_names[r] = "";

  /* Do, however, supply default names for the known special-purpose
     registers.  */

  var->register_names[pc_regnum] = "pc";
  var->register_names[lr_regnum] = "lr";
  var->register_names[lcr_regnum] = "lcr";
     
  var->register_names[psr_regnum] = "psr";
  var->register_names[ccr_regnum] = "ccr";
  var->register_names[cccr_regnum] = "cccr";
  var->register_names[tbr_regnum] = "tbr";

  /* Debug registers.  */
  var->register_names[brr_regnum] = "brr";
  var->register_names[dbar0_regnum] = "dbar0";
  var->register_names[dbar1_regnum] = "dbar1";
  var->register_names[dbar2_regnum] = "dbar2";
  var->register_names[dbar3_regnum] = "dbar3";

  /* iacc0 (Only found on MB93405.)  */
  var->register_names[iacc0h_regnum] = "iacc0h";
  var->register_names[iacc0l_regnum] = "iacc0l";
  var->register_names[iacc0_regnum] = "iacc0";

  /* fsr0 (Found on FR555 and FR501.)  */
  var->register_names[fsr0_regnum] = "fsr0";

  /* acc0 - acc7.  The architecture provides for the possibility of many
     more (up to 64 total), but we don't want to make that big of a hole
     in the G packet.  If we need more in the future, we'll add them
     elsewhere.  */
  for (r = acc0_regnum; r <= acc7_regnum; r++)
    {
      char *buf;
      buf = xstrprintf ("acc%d", r - acc0_regnum);
      var->register_names[r] = buf;
    }

  /* accg0 - accg7: These are one byte registers.  The remote protocol
     provides the raw values packed four into a slot.  accg0123 and
     accg4567 correspond to accg0 - accg3 and accg4-accg7 respectively.
     We don't provide names for accg0123 and accg4567 since the user will
     likely not want to see these raw values.  */

  for (r = accg0_regnum; r <= accg7_regnum; r++)
    {
      char *buf;
      buf = xstrprintf ("accg%d", r - accg0_regnum);
      var->register_names[r] = buf;
    }

  /* msr0 and msr1.  */

  var->register_names[msr0_regnum] = "msr0";
  var->register_names[msr1_regnum] = "msr1";

  /* gner and fner registers.  */
  var->register_names[gner0_regnum] = "gner0";
  var->register_names[gner1_regnum] = "gner1";
  var->register_names[fner0_regnum] = "fner0";
  var->register_names[fner1_regnum] = "fner1";

  return var;
}


/* Indicate that the variant VAR has NUM_GPRS general-purpose
   registers, and fill in the names array appropriately.  */
static void
set_variant_num_gprs (struct gdbarch_tdep *var, int num_gprs)
{
  int r;

  var->num_gprs = num_gprs;

  for (r = 0; r < num_gprs; ++r)
    {
      char buf[20];

      xsnprintf (buf, sizeof (buf), "gr%d", r);
      var->register_names[first_gpr_regnum + r] = xstrdup (buf);
    }
}


/* Indicate that the variant VAR has NUM_FPRS floating-point
   registers, and fill in the names array appropriately.  */
static void
set_variant_num_fprs (struct gdbarch_tdep *var, int num_fprs)
{
  int r;

  var->num_fprs = num_fprs;

  for (r = 0; r < num_fprs; ++r)
    {
      char buf[20];

      xsnprintf (buf, sizeof (buf), "fr%d", r);
      var->register_names[first_fpr_regnum + r] = xstrdup (buf);
    }
}

static void
set_variant_abi_fdpic (struct gdbarch_tdep *var)
{
  var->frv_abi = FRV_ABI_FDPIC;
  var->register_names[fdpic_loadmap_exec_regnum] = xstrdup ("loadmap_exec");
  var->register_names[fdpic_loadmap_interp_regnum]
    = xstrdup ("loadmap_interp");
}

static void
set_variant_scratch_registers (struct gdbarch_tdep *var)
{
  var->register_names[scr0_regnum] = xstrdup ("scr0");
  var->register_names[scr1_regnum] = xstrdup ("scr1");
  var->register_names[scr2_regnum] = xstrdup ("scr2");
  var->register_names[scr3_regnum] = xstrdup ("scr3");
}

static const char *
frv_register_name (struct gdbarch *gdbarch, int reg)
{
  if (reg < 0)
    return "?toosmall?";
  if (reg >= frv_num_regs + frv_num_pseudo_regs)
    return "?toolarge?";

  return gdbarch_tdep (gdbarch)->register_names[reg];
}


static struct type *
frv_register_type (struct gdbarch *gdbarch, int reg)
{
  if (reg >= first_fpr_regnum && reg <= last_fpr_regnum)
    return builtin_type (gdbarch)->builtin_float;
  else if (reg == iacc0_regnum)
    return builtin_type (gdbarch)->builtin_int64;
  else
    return builtin_type (gdbarch)->builtin_int32;
}

static enum register_status
frv_pseudo_register_read (struct gdbarch *gdbarch, readable_regcache *regcache,
                          int reg, gdb_byte *buffer)
{
  enum register_status status;

  if (reg == iacc0_regnum)
    {
      status = regcache->raw_read (iacc0h_regnum, buffer);
      if (status == REG_VALID)
	status = regcache->raw_read (iacc0l_regnum, (bfd_byte *) buffer + 4);
    }
  else if (accg0_regnum <= reg && reg <= accg7_regnum)
    {
      /* The accg raw registers have four values in each slot with the
         lowest register number occupying the first byte.  */

      int raw_regnum = accg0123_regnum + (reg - accg0_regnum) / 4;
      int byte_num = (reg - accg0_regnum) % 4;
      gdb_byte buf[4];

      status = regcache->raw_read (raw_regnum, buf);
      if (status == REG_VALID)
	{
	  memset (buffer, 0, 4);
	  /* FR-V is big endian, so put the requested byte in the
	     first byte of the buffer allocated to hold the
	     pseudo-register.  */
	  buffer[0] = buf[byte_num];
	}
    }
  else
    gdb_assert_not_reached ("invalid pseudo register number");

  return status;
}

static void
frv_pseudo_register_write (struct gdbarch *gdbarch, struct regcache *regcache,
                          int reg, const gdb_byte *buffer)
{
  if (reg == iacc0_regnum)
    {
      regcache->raw_write (iacc0h_regnum, buffer);
      regcache->raw_write (iacc0l_regnum, (bfd_byte *) buffer + 4);
    }
  else if (accg0_regnum <= reg && reg <= accg7_regnum)
    {
      /* The accg raw registers have four values in each slot with the
         lowest register number occupying the first byte.  */

      int raw_regnum = accg0123_regnum + (reg - accg0_regnum) / 4;
      int byte_num = (reg - accg0_regnum) % 4;
      gdb_byte buf[4];

      regcache->raw_read (raw_regnum, buf);
      buf[byte_num] = ((bfd_byte *) buffer)[0];
      regcache->raw_write (raw_regnum, buf);
    }
}

static int
frv_register_sim_regno (struct gdbarch *gdbarch, int reg)
{
  static const int spr_map[] =
    {
      H_SPR_PSR,		/* psr_regnum */
      H_SPR_CCR,		/* ccr_regnum */
      H_SPR_CCCR,		/* cccr_regnum */
      -1,			/* fdpic_loadmap_exec_regnum */
      -1,			/* fdpic_loadmap_interp_regnum */
      -1,			/* 134 */
      H_SPR_TBR,		/* tbr_regnum */
      H_SPR_BRR,		/* brr_regnum */
      H_SPR_DBAR0,		/* dbar0_regnum */
      H_SPR_DBAR1,		/* dbar1_regnum */
      H_SPR_DBAR2,		/* dbar2_regnum */
      H_SPR_DBAR3,		/* dbar3_regnum */
      H_SPR_SCR0,		/* scr0_regnum */
      H_SPR_SCR1,		/* scr1_regnum */
      H_SPR_SCR2,		/* scr2_regnum */
      H_SPR_SCR3,		/* scr3_regnum */
      H_SPR_LR,			/* lr_regnum */
      H_SPR_LCR,		/* lcr_regnum */
      H_SPR_IACC0H,		/* iacc0h_regnum */
      H_SPR_IACC0L,		/* iacc0l_regnum */
      H_SPR_FSR0,		/* fsr0_regnum */
      /* FIXME: Add infrastructure for fetching/setting ACC and ACCG regs.  */
      -1,			/* acc0_regnum */
      -1,			/* acc1_regnum */
      -1,			/* acc2_regnum */
      -1,			/* acc3_regnum */
      -1,			/* acc4_regnum */
      -1,			/* acc5_regnum */
      -1,			/* acc6_regnum */
      -1,			/* acc7_regnum */
      -1,			/* acc0123_regnum */
      -1,			/* acc4567_regnum */
      H_SPR_MSR0,		/* msr0_regnum */
      H_SPR_MSR1,		/* msr1_regnum */
      H_SPR_GNER0,		/* gner0_regnum */
      H_SPR_GNER1,		/* gner1_regnum */
      H_SPR_FNER0,		/* fner0_regnum */
      H_SPR_FNER1,		/* fner1_regnum */
    };

  gdb_assert (reg >= 0 && reg < gdbarch_num_regs (gdbarch));

  if (first_gpr_regnum <= reg && reg <= last_gpr_regnum)
    return reg - first_gpr_regnum + SIM_FRV_GR0_REGNUM;
  else if (first_fpr_regnum <= reg && reg <= last_fpr_regnum)
    return reg - first_fpr_regnum + SIM_FRV_FR0_REGNUM;
  else if (pc_regnum == reg)
    return SIM_FRV_PC_REGNUM;
  else if (reg >= first_spr_regnum
           && reg < first_spr_regnum + sizeof (spr_map) / sizeof (spr_map[0]))
    {
      int spr_reg_offset = spr_map[reg - first_spr_regnum];

      if (spr_reg_offset < 0)
	return SIM_REGNO_DOES_NOT_EXIST;
      else
	return SIM_FRV_SPR0_REGNUM + spr_reg_offset;
    }

  internal_error (__FILE__, __LINE__, _("Bad register number %d"), reg);
}

constexpr gdb_byte frv_break_insn[] = {0xc0, 0x70, 0x00, 0x01};

typedef BP_MANIPULATION (frv_break_insn) frv_breakpoint;

/* Define the maximum number of instructions which may be packed into a
   bundle (VLIW instruction).  */
static const int max_instrs_per_bundle = 8;

/* Define the size (in bytes) of an FR-V instruction.  */
static const int frv_instr_size = 4;

/* Adjust a breakpoint's address to account for the FR-V architecture's
   constraint that a break instruction must not appear as any but the
   first instruction in the bundle.  */
static CORE_ADDR
frv_adjust_breakpoint_address (struct gdbarch *gdbarch, CORE_ADDR bpaddr)
{
  int count = max_instrs_per_bundle;
  CORE_ADDR addr = bpaddr - frv_instr_size;
  CORE_ADDR func_start = get_pc_function_start (bpaddr);

  /* Find the end of the previous packing sequence.  This will be indicated
     by either attempting to access some inaccessible memory or by finding
     an instruction word whose packing bit is set to one.  */
  while (count-- > 0 && addr >= func_start)
    {
      gdb_byte instr[frv_instr_size];
      int status;

      status = target_read_memory (addr, instr, sizeof instr);

      if (status != 0)
	break;

      /* This is a big endian architecture, so byte zero will have most
         significant byte.  The most significant bit of this byte is the
         packing bit.  */
      if (instr[0] & 0x80)
	break;

      addr -= frv_instr_size;
    }

  if (count > 0)
    bpaddr = addr + frv_instr_size;

  return bpaddr;
}


/* Return true if REG is a caller-saves ("scratch") register,
   false otherwise.  */
static int
is_caller_saves_reg (int reg)
{
  return ((4 <= reg && reg <= 7)
          || (14 <= reg && reg <= 15)
          || (32 <= reg && reg <= 47));
}


/* Return true if REG is a callee-saves register, false otherwise.  */
static int
is_callee_saves_reg (int reg)
{
  return ((16 <= reg && reg <= 31)
          || (48 <= reg && reg <= 63));
}


/* Return true if REG is an argument register, false otherwise.  */
static int
is_argument_reg (int reg)
{
  return (8 <= reg && reg <= 13);
}

/* Scan an FR-V prologue, starting at PC, until frame->PC.
   If FRAME is non-zero, fill in its saved_regs with appropriate addresses.
   We assume FRAME's saved_regs array has already been allocated and cleared.
   Return the first PC value after the prologue.

   Note that, for unoptimized code, we almost don't need this function
   at all; all arguments and locals live on the stack, so we just need
   the FP to find everything.  The catch: structures passed by value
   have their addresses living in registers; they're never spilled to
   the stack.  So if you ever want to be able to get to these
   arguments in any frame but the top, you'll need to do this serious
   prologue analysis.  */
static CORE_ADDR
frv_analyze_prologue (struct gdbarch *gdbarch, CORE_ADDR pc,
		      struct frame_info *this_frame,
                      struct frv_unwind_cache *info)
{
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  /* When writing out instruction bitpatterns, we use the following
     letters to label instruction fields:
     P - The parallel bit.  We don't use this.
     J - The register number of GRj in the instruction description.
     K - The register number of GRk in the instruction description.
     I - The register number of GRi.
     S - a signed immediate offset.
     U - an unsigned immediate offset.

     The dots below the numbers indicate where hex digit boundaries
     fall, to make it easier to check the numbers.  */

  /* Non-zero iff we've seen the instruction that initializes the
     frame pointer for this function's frame.  */
  int fp_set = 0;

  /* If fp_set is non_zero, then this is the distance from
     the stack pointer to frame pointer: fp = sp + fp_offset.  */
  int fp_offset = 0;

  /* Total size of frame prior to any alloca operations.  */
  int framesize = 0;

  /* Flag indicating if lr has been saved on the stack.  */
  int lr_saved_on_stack = 0;

  /* The number of the general-purpose register we saved the return
     address ("link register") in, or -1 if we haven't moved it yet.  */
  int lr_save_reg = -1;

  /* Offset (from sp) at which lr has been saved on the stack.  */

  int lr_sp_offset = 0;

  /* If gr_saved[i] is non-zero, then we've noticed that general
     register i has been saved at gr_sp_offset[i] from the stack
     pointer.  */
  char gr_saved[64];
  int gr_sp_offset[64];

  /* The address of the most recently scanned prologue instruction.  */
  CORE_ADDR last_prologue_pc;

  /* The address of the next instruction.  */
  CORE_ADDR next_pc;

  /* The upper bound to of the pc values to scan.  */
  CORE_ADDR lim_pc;

  memset (gr_saved, 0, sizeof (gr_saved));

  last_prologue_pc = pc;

  /* Try to compute an upper limit (on how far to scan) based on the
     line number info.  */
  lim_pc = skip_prologue_using_sal (gdbarch, pc);
  /* If there's no line number info, lim_pc will be 0.  In that case,
     set the limit to be 100 instructions away from pc.  Hopefully, this
     will be far enough away to account for the entire prologue.  Don't
     worry about overshooting the end of the function.  The scan loop
     below contains some checks to avoid scanning unreasonably far.  */
  if (lim_pc == 0)
    lim_pc = pc + 400;

  /* If we have a frame, we don't want to scan past the frame's pc.  This
     will catch those cases where the pc is in the prologue.  */
  if (this_frame)
    {
      CORE_ADDR frame_pc = get_frame_pc (this_frame);
      if (frame_pc < lim_pc)
	lim_pc = frame_pc;
    }

  /* Scan the prologue.  */
  while (pc < lim_pc)
    {
      gdb_byte buf[frv_instr_size];
      LONGEST op;

      if (target_read_memory (pc, buf, sizeof buf) != 0)
	break;
      op = extract_signed_integer (buf, sizeof buf, byte_order);

      next_pc = pc + 4;

      /* The tests in this chain of ifs should be in order of
	 decreasing selectivity, so that more particular patterns get
	 to fire before less particular patterns.  */

      /* Some sort of control transfer instruction: stop scanning prologue.
	 Integer Conditional Branch:
	  X XXXX XX 0000110 XX XXXXXXXXXXXXXXXX
	 Floating-point / media Conditional Branch:
	  X XXXX XX 0000111 XX XXXXXXXXXXXXXXXX
	 LCR Conditional Branch to LR
	  X XXXX XX 0001110 XX XX 001 X XXXXXXXXXX
	 Integer conditional Branches to LR
	  X XXXX XX 0001110 XX XX 010 X XXXXXXXXXX
	  X XXXX XX 0001110 XX XX 011 X XXXXXXXXXX
	 Floating-point/Media Branches to LR
	  X XXXX XX 0001110 XX XX 110 X XXXXXXXXXX
	  X XXXX XX 0001110 XX XX 111 X XXXXXXXXXX
	 Jump and Link
	  X XXXXX X 0001100 XXXXXX XXXXXX XXXXXX
	  X XXXXX X 0001101 XXXXXX XXXXXX XXXXXX
	 Call
	  X XXXXXX 0001111 XXXXXXXXXXXXXXXXXX
	 Return from Trap
	  X XXXXX X 0000101 XXXXXX XXXXXX XXXXXX
	 Integer Conditional Trap
	  X XXXX XX 0000100 XXXXXX XXXX 00 XXXXXX
	  X XXXX XX 0011100 XXXXXX XXXXXXXXXXXX
	 Floating-point /media Conditional Trap
	  X XXXX XX 0000100 XXXXXX XXXX 01 XXXXXX
	  X XXXX XX 0011101 XXXXXX XXXXXXXXXXXX
	 Break
	  X XXXX XX 0000100 XXXXXX XXXX 11 XXXXXX
	 Media Trap
	  X XXXX XX 0000100 XXXXXX XXXX 10 XXXXXX */
      if ((op & 0x01d80000) == 0x00180000 /* Conditional branches and Call */
          || (op & 0x01f80000) == 0x00300000  /* Jump and Link */
	  || (op & 0x01f80000) == 0x00100000  /* Return from Trap, Trap */
	  || (op & 0x01f80000) == 0x00700000) /* Trap immediate */
	{
	  /* Stop scanning; not in prologue any longer.  */
	  break;
	}

      /* Loading something from memory into fp probably means that
         we're in the epilogue.  Stop scanning the prologue.
         ld @(GRi, GRk), fp
	 X 000010 0000010 XXXXXX 000100 XXXXXX
	 ldi @(GRi, d12), fp
	 X 000010 0110010 XXXXXX XXXXXXXXXXXX */
      else if ((op & 0x7ffc0fc0) == 0x04080100
               || (op & 0x7ffc0000) == 0x04c80000)
	{
	  break;
	}

      /* Setting the FP from the SP:
	 ori sp, 0, fp
	 P 000010 0100010 000001 000000000000 = 0x04881000
	 0 111111 1111111 111111 111111111111 = 0x7fffffff
             .    .   .    .   .    .   .   .
	 We treat this as part of the prologue.  */
      else if ((op & 0x7fffffff) == 0x04881000)
	{
	  fp_set = 1;
	  fp_offset = 0;
	  last_prologue_pc = next_pc;
	}

      /* Move the link register to the scratch register grJ, before saving:
         movsg lr, grJ
         P 000100 0000011 010000 000111 JJJJJJ = 0x080d01c0
         0 111111 1111111 111111 111111 000000 = 0x7fffffc0
             .    .   .    .   .    .    .   .
	 We treat this as part of the prologue.  */
      else if ((op & 0x7fffffc0) == 0x080d01c0)
        {
          int gr_j = op & 0x3f;

          /* If we're moving it to a scratch register, that's fine.  */
          if (is_caller_saves_reg (gr_j))
	    {
	      lr_save_reg = gr_j;
	      last_prologue_pc = next_pc;
	    }
        }

      /* To save multiple callee-saves registers on the stack, at
         offset zero:

	 std grK,@(sp,gr0)
	 P KKKKKK 0000011 000001 000011 000000 = 0x000c10c0
	 0 000000 1111111 111111 111111 111111 = 0x01ffffff

	 stq grK,@(sp,gr0)
	 P KKKKKK 0000011 000001 000100 000000 = 0x000c1100
	 0 000000 1111111 111111 111111 111111 = 0x01ffffff
             .    .   .    .   .    .    .   .
         We treat this as part of the prologue, and record the register's
	 saved address in the frame structure.  */
      else if ((op & 0x01ffffff) == 0x000c10c0
            || (op & 0x01ffffff) == 0x000c1100)
	{
	  int gr_k = ((op >> 25) & 0x3f);
	  int ope  = ((op >> 6)  & 0x3f);
          int count;
	  int i;

          /* Is it an std or an stq?  */
          if (ope == 0x03)
            count = 2;
          else
            count = 4;

	  /* Is it really a callee-saves register?  */
	  if (is_callee_saves_reg (gr_k))
	    {
	      for (i = 0; i < count; i++)
	        {
		  gr_saved[gr_k + i] = 1;
		  gr_sp_offset[gr_k + i] = 4 * i;
		}
	      last_prologue_pc = next_pc;
	    }
	}

      /* Adjusting the stack pointer.  (The stack pointer is GR1.)
	 addi sp, S, sp
         P 000001 0010000 000001 SSSSSSSSSSSS = 0x02401000
         0 111111 1111111 111111 000000000000 = 0x7ffff000
             .    .   .    .   .    .   .   .
	 We treat this as part of the prologue.  */
      else if ((op & 0x7ffff000) == 0x02401000)
        {
	  if (framesize == 0)
	    {
	      /* Sign-extend the twelve-bit field.
		 (Isn't there a better way to do this?)  */
	      int s = (((op & 0xfff) - 0x800) & 0xfff) - 0x800;

	      framesize -= s;
	      last_prologue_pc = pc;
	    }
	  else
	    {
	      /* If the prologue is being adjusted again, we've
	         likely gone too far; i.e. we're probably in the
		 epilogue.  */
	      break;
	    }
	}

      /* Setting the FP to a constant distance from the SP:
	 addi sp, S, fp
         P 000010 0010000 000001 SSSSSSSSSSSS = 0x04401000
         0 111111 1111111 111111 000000000000 = 0x7ffff000
             .    .   .    .   .    .   .   .
	 We treat this as part of the prologue.  */
      else if ((op & 0x7ffff000) == 0x04401000)
	{
	  /* Sign-extend the twelve-bit field.
	     (Isn't there a better way to do this?)  */
	  int s = (((op & 0xfff) - 0x800) & 0xfff) - 0x800;
	  fp_set = 1;
	  fp_offset = s;
	  last_prologue_pc = pc;
	}

      /* To spill an argument register to a scratch register:
	    ori GRi, 0, GRk
	 P KKKKKK 0100010 IIIIII 000000000000 = 0x00880000
	 0 000000 1111111 000000 111111111111 = 0x01fc0fff
	     .    .   .    .   .    .   .   .
	 For the time being, we treat this as a prologue instruction,
	 assuming that GRi is an argument register.  This one's kind
	 of suspicious, because it seems like it could be part of a
	 legitimate body instruction.  But we only come here when the
	 source info wasn't helpful, so we have to do the best we can.
	 Hopefully once GCC and GDB agree on how to emit line number
	 info for prologues, then this code will never come into play.  */
      else if ((op & 0x01fc0fff) == 0x00880000)
	{
	  int gr_i = ((op >> 12) & 0x3f);

          /* Make sure that the source is an arg register; if it is, we'll
	     treat it as a prologue instruction.  */
	  if (is_argument_reg (gr_i))
	    last_prologue_pc = next_pc;
	}

      /* To spill 16-bit values to the stack:
	     sthi GRk, @(fp, s)
	 P KKKKKK 1010001 000010 SSSSSSSSSSSS = 0x01442000
	 0 000000 1111111 111111 000000000000 = 0x01fff000
             .    .   .    .   .    .   .   . 
         And for 8-bit values, we use STB instructions.
	     stbi GRk, @(fp, s)
	 P KKKKKK 1010000 000010 SSSSSSSSSSSS = 0x01402000
	 0 000000 1111111 111111 000000000000 = 0x01fff000
	     .    .   .    .   .    .   .   .
         We check that GRk is really an argument register, and treat
         all such as part of the prologue.  */
      else if (   (op & 0x01fff000) == 0x01442000
	       || (op & 0x01fff000) == 0x01402000)
	{
	  int gr_k = ((op >> 25) & 0x3f);

          /* Make sure that GRk is really an argument register; treat
	     it as a prologue instruction if so.  */
	  if (is_argument_reg (gr_k))
	    last_prologue_pc = next_pc;
	}

      /* To save multiple callee-saves register on the stack, at a
         non-zero offset:

	 stdi GRk, @(sp, s)
	 P KKKKKK 1010011 000001 SSSSSSSSSSSS = 0x014c1000
	 0 000000 1111111 111111 000000000000 = 0x01fff000
             .    .   .    .   .    .   .   .
	 stqi GRk, @(sp, s)
	 P KKKKKK 1010100 000001 SSSSSSSSSSSS = 0x01501000
	 0 000000 1111111 111111 000000000000 = 0x01fff000
	     .    .   .    .   .    .   .   .
         We treat this as part of the prologue, and record the register's
	 saved address in the frame structure.  */
      else if ((op & 0x01fff000) == 0x014c1000
            || (op & 0x01fff000) == 0x01501000)
	{
	  int gr_k = ((op >> 25) & 0x3f);
          int count;
	  int i;

          /* Is it a stdi or a stqi?  */
          if ((op & 0x01fff000) == 0x014c1000)
            count = 2;
          else
            count = 4;

	  /* Is it really a callee-saves register?  */
	  if (is_callee_saves_reg (gr_k))
	    {
	      /* Sign-extend the twelve-bit field.
		 (Isn't there a better way to do this?)  */
	      int s = (((op & 0xfff) - 0x800) & 0xfff) - 0x800;

	      for (i = 0; i < count; i++)
		{
		  gr_saved[gr_k + i] = 1;
		  gr_sp_offset[gr_k + i] = s + (4 * i);
		}
	      last_prologue_pc = next_pc;
	    }
	}

      /* Storing any kind of integer register at any constant offset
         from any other register.

	 st GRk, @(GRi, gr0)
         P KKKKKK 0000011 IIIIII 000010 000000 = 0x000c0080
         0 000000 1111111 000000 111111 111111 = 0x01fc0fff
             .    .   .    .   .    .    .   .
	 sti GRk, @(GRi, d12)
	 P KKKKKK 1010010 IIIIII SSSSSSSSSSSS = 0x01480000
	 0 000000 1111111 000000 000000000000 = 0x01fc0000
             .    .   .    .   .    .   .   .
         These could be almost anything, but a lot of prologue
         instructions fall into this pattern, so let's decode the
         instruction once, and then work at a higher level.  */
      else if (((op & 0x01fc0fff) == 0x000c0080)
            || ((op & 0x01fc0000) == 0x01480000))
        {
          int gr_k = ((op >> 25) & 0x3f);
          int gr_i = ((op >> 12) & 0x3f);
          int offset;

          /* Are we storing with gr0 as an offset, or using an
             immediate value?  */
          if ((op & 0x01fc0fff) == 0x000c0080)
            offset = 0;
          else
            offset = (((op & 0xfff) - 0x800) & 0xfff) - 0x800;

          /* If the address isn't relative to the SP or FP, it's not a
             prologue instruction.  */
          if (gr_i != sp_regnum && gr_i != fp_regnum)
	    {
	      /* Do nothing; not a prologue instruction.  */
	    }

          /* Saving the old FP in the new frame (relative to the SP).  */
          else if (gr_k == fp_regnum && gr_i == sp_regnum)
	    {
	      gr_saved[fp_regnum] = 1;
              gr_sp_offset[fp_regnum] = offset;
	      last_prologue_pc = next_pc;
	    }

          /* Saving callee-saves register(s) on the stack, relative to
             the SP.  */
          else if (gr_i == sp_regnum
                   && is_callee_saves_reg (gr_k))
            {
              gr_saved[gr_k] = 1;
	      if (gr_i == sp_regnum)
		gr_sp_offset[gr_k] = offset;
	      else
		gr_sp_offset[gr_k] = offset + fp_offset;
	      last_prologue_pc = next_pc;
            }

          /* Saving the scratch register holding the return address.  */
          else if (lr_save_reg != -1
                   && gr_k == lr_save_reg)
	    {
	      lr_saved_on_stack = 1;
	      if (gr_i == sp_regnum)
		lr_sp_offset = offset;
	      else
	        lr_sp_offset = offset + fp_offset;
	      last_prologue_pc = next_pc;
	    }

          /* Spilling int-sized arguments to the stack.  */
          else if (is_argument_reg (gr_k))
	    last_prologue_pc = next_pc;
        }
      pc = next_pc;
    }

  if (this_frame && info)
    {
      int i;
      ULONGEST this_base;

      /* If we know the relationship between the stack and frame
         pointers, record the addresses of the registers we noticed.
         Note that we have to do this as a separate step at the end,
         because instructions may save relative to the SP, but we need
         their addresses relative to the FP.  */
      if (fp_set)
	this_base = get_frame_register_unsigned (this_frame, fp_regnum);
      else
	this_base = get_frame_register_unsigned (this_frame, sp_regnum);

      for (i = 0; i < 64; i++)
	if (gr_saved[i])
	  info->saved_regs[i].addr = this_base - fp_offset + gr_sp_offset[i];

      info->prev_sp = this_base - fp_offset + framesize;
      info->base = this_base;

      /* If LR was saved on the stack, record its location.  */
      if (lr_saved_on_stack)
	info->saved_regs[lr_regnum].addr
	  = this_base - fp_offset + lr_sp_offset;

      /* The call instruction moves the caller's PC in the callee's LR.
	 Since this is an unwind, do the reverse.  Copy the location of LR
	 into PC (the address / regnum) so that a request for PC will be
	 converted into a request for the LR.  */
      info->saved_regs[pc_regnum] = info->saved_regs[lr_regnum];

      /* Save the previous frame's computed SP value.  */
      trad_frame_set_value (info->saved_regs, sp_regnum, info->prev_sp);
    }

  return last_prologue_pc;
}


static CORE_ADDR
frv_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
{
  CORE_ADDR func_addr, func_end, new_pc;

  new_pc = pc;

  /* If the line table has entry for a line *within* the function
     (i.e., not in the prologue, and not past the end), then that's
     our location.  */
  if (find_pc_partial_function (pc, NULL, &func_addr, &func_end))
    {
      struct symtab_and_line sal;

      sal = find_pc_line (func_addr, 0);

      if (sal.line != 0 && sal.end < func_end)
	{
	  new_pc = sal.end;
	}
    }

  /* The FR-V prologue is at least five instructions long (twenty bytes).
     If we didn't find a real source location past that, then
     do a full analysis of the prologue.  */
  if (new_pc < pc + 20)
    new_pc = frv_analyze_prologue (gdbarch, pc, 0, 0);

  return new_pc;
}


/* Examine the instruction pointed to by PC.  If it corresponds to
   a call to __main, return the address of the next instruction.
   Otherwise, return PC.  */

static CORE_ADDR
frv_skip_main_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
{
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  gdb_byte buf[4];
  unsigned long op;
  CORE_ADDR orig_pc = pc;

  if (target_read_memory (pc, buf, 4))
    return pc;
  op = extract_unsigned_integer (buf, 4, byte_order);

  /* In PIC code, GR15 may be loaded from some offset off of FP prior
     to the call instruction.
     
     Skip over this instruction if present.  It won't be present in
     non-PIC code, and even in PIC code, it might not be present.
     (This is due to the fact that GR15, the FDPIC register, already
     contains the correct value.)

     The general form of the LDI is given first, followed by the
     specific instruction with the GRi and GRk filled in as FP and
     GR15.

     ldi @(GRi, d12), GRk
     P KKKKKK 0110010 IIIIII SSSSSSSSSSSS = 0x00c80000
     0 000000 1111111 000000 000000000000 = 0x01fc0000
	 .    .   .    .   .    .   .   .
     ldi @(FP, d12), GR15
     P KKKKKK 0110010 IIIIII SSSSSSSSSSSS = 0x1ec82000
     0 001111 1111111 000010 000000000000 = 0x7ffff000
	 .    .   .    .   .    .   .   .               */

  if ((op & 0x7ffff000) == 0x1ec82000)
    {
      pc += 4;
      if (target_read_memory (pc, buf, 4))
	return orig_pc;
      op = extract_unsigned_integer (buf, 4, byte_order);
    }

  /* The format of an FRV CALL instruction is as follows:

     call label24
     P HHHHHH 0001111 LLLLLLLLLLLLLLLLLL = 0x003c0000
     0 000000 1111111 000000000000000000 = 0x01fc0000
         .    .   .    .   .   .   .   .

     where label24 is constructed by concatenating the H bits with the
     L bits.  The call target is PC + (4 * sign_ext(label24)).  */

  if ((op & 0x01fc0000) == 0x003c0000)
    {
      LONGEST displ;
      CORE_ADDR call_dest;
      struct bound_minimal_symbol s;

      displ = ((op & 0xfe000000) >> 7) | (op & 0x0003ffff);
      if ((displ & 0x00800000) != 0)
	displ |= ~((LONGEST) 0x00ffffff);

      call_dest = pc + 4 * displ;
      s = lookup_minimal_symbol_by_pc (call_dest);

      if (s.minsym != NULL
          && s.minsym->linkage_name () != NULL
	  && strcmp (s.minsym->linkage_name (), "__main") == 0)
	{
	  pc += 4;
	  return pc;
	}
    }
  return orig_pc;
}


static struct frv_unwind_cache *
frv_frame_unwind_cache (struct frame_info *this_frame,
			 void **this_prologue_cache)
{
  struct gdbarch *gdbarch = get_frame_arch (this_frame);
  struct frv_unwind_cache *info;

  if ((*this_prologue_cache))
    return (struct frv_unwind_cache *) (*this_prologue_cache);

  info = FRAME_OBSTACK_ZALLOC (struct frv_unwind_cache);
  (*this_prologue_cache) = info;
  info->saved_regs = trad_frame_alloc_saved_regs (this_frame);

  /* Prologue analysis does the rest...  */
  frv_analyze_prologue (gdbarch,
			get_frame_func (this_frame), this_frame, info);

  return info;
}

static void
frv_extract_return_value (struct type *type, struct regcache *regcache,
                          gdb_byte *valbuf)
{
  struct gdbarch *gdbarch = regcache->arch ();
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  int len = TYPE_LENGTH (type);

  if (len <= 4)
    {
      ULONGEST gpr8_val;
      regcache_cooked_read_unsigned (regcache, 8, &gpr8_val);
      store_unsigned_integer (valbuf, len, byte_order, gpr8_val);
    }
  else if (len == 8)
    {
      ULONGEST regval;

      regcache_cooked_read_unsigned (regcache, 8, &regval);
      store_unsigned_integer (valbuf, 4, byte_order, regval);
      regcache_cooked_read_unsigned (regcache, 9, &regval);
      store_unsigned_integer ((bfd_byte *) valbuf + 4, 4, byte_order, regval);
    }
  else
    internal_error (__FILE__, __LINE__,
		    _("Illegal return value length: %d"), len);
}

static CORE_ADDR
frv_frame_align (struct gdbarch *gdbarch, CORE_ADDR sp)
{
  /* Require dword alignment.  */
  return align_down (sp, 8);
}

static CORE_ADDR
find_func_descr (struct gdbarch *gdbarch, CORE_ADDR entry_point)
{
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  CORE_ADDR descr;
  gdb_byte valbuf[4];
  CORE_ADDR start_addr;

  /* If we can't find the function in the symbol table, then we assume
     that the function address is already in descriptor form.  */
  if (!find_pc_partial_function (entry_point, NULL, &start_addr, NULL)
      || entry_point != start_addr)
    return entry_point;

  descr = frv_fdpic_find_canonical_descriptor (entry_point);

  if (descr != 0)
    return descr;

  /* Construct a non-canonical descriptor from space allocated on
     the stack.  */

  descr = value_as_long (value_allocate_space_in_inferior (8));
  store_unsigned_integer (valbuf, 4, byte_order, entry_point);
  write_memory (descr, valbuf, 4);
  store_unsigned_integer (valbuf, 4, byte_order,
                          frv_fdpic_find_global_pointer (entry_point));
  write_memory (descr + 4, valbuf, 4);
  return descr;
}

static CORE_ADDR
frv_convert_from_func_ptr_addr (struct gdbarch *gdbarch, CORE_ADDR addr,
                                struct target_ops *targ)
{
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  CORE_ADDR entry_point;
  CORE_ADDR got_address;

  entry_point = get_target_memory_unsigned (targ, addr, 4, byte_order);
  got_address = get_target_memory_unsigned (targ, addr + 4, 4, byte_order);

  if (got_address == frv_fdpic_find_global_pointer (entry_point))
    return entry_point;
  else
    return addr;
}

static CORE_ADDR
frv_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
                     struct regcache *regcache, CORE_ADDR bp_addr,
                     int nargs, struct value **args, CORE_ADDR sp,
		     function_call_return_method return_method,
		     CORE_ADDR struct_addr)
{
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  int argreg;
  int argnum;
  const gdb_byte *val;
  gdb_byte valbuf[4];
  struct value *arg;
  struct type *arg_type;
  int len;
  enum type_code typecode;
  CORE_ADDR regval;
  int stack_space;
  int stack_offset;
  enum frv_abi abi = frv_abi (gdbarch);
  CORE_ADDR func_addr = find_function_addr (function, NULL);

#if 0
  printf("Push %d args at sp = %x, struct_return=%d (%x)\n",
	 nargs, (int) sp, struct_return, struct_addr);
#endif

  stack_space = 0;
  for (argnum = 0; argnum < nargs; ++argnum)
    stack_space += align_up (TYPE_LENGTH (value_type (args[argnum])), 4);

  stack_space -= (6 * 4);
  if (stack_space > 0)
    sp -= stack_space;

  /* Make sure stack is dword aligned.  */
  sp = align_down (sp, 8);

  stack_offset = 0;

  argreg = 8;

  if (return_method == return_method_struct)
    regcache_cooked_write_unsigned (regcache, struct_return_regnum,
                                    struct_addr);

  for (argnum = 0; argnum < nargs; ++argnum)
    {
      arg = args[argnum];
      arg_type = check_typedef (value_type (arg));
      len = TYPE_LENGTH (arg_type);
      typecode = TYPE_CODE (arg_type);

      if (typecode == TYPE_CODE_STRUCT || typecode == TYPE_CODE_UNION)
	{
	  store_unsigned_integer (valbuf, 4, byte_order,
				  value_address (arg));
	  typecode = TYPE_CODE_PTR;
	  len = 4;
	  val = valbuf;
	}
      else if (abi == FRV_ABI_FDPIC
	       && len == 4
               && typecode == TYPE_CODE_PTR
               && TYPE_CODE (TYPE_TARGET_TYPE (arg_type)) == TYPE_CODE_FUNC)
	{
	  /* The FDPIC ABI requires function descriptors to be passed instead
	     of entry points.  */
	  CORE_ADDR addr = extract_unsigned_integer
			     (value_contents (arg), 4, byte_order);
	  addr = find_func_descr (gdbarch, addr);
	  store_unsigned_integer (valbuf, 4, byte_order, addr);
	  typecode = TYPE_CODE_PTR;
	  len = 4;
	  val = valbuf;
	}
      else
	{
	  val = value_contents (arg);
	}

      while (len > 0)
	{
	  int partial_len = (len < 4 ? len : 4);

	  if (argreg < 14)
	    {
	      regval = extract_unsigned_integer (val, partial_len, byte_order);
#if 0
	      printf("  Argnum %d data %x -> reg %d\n",
		     argnum, (int) regval, argreg);
#endif
	      regcache_cooked_write_unsigned (regcache, argreg, regval);
	      ++argreg;
	    }
	  else
	    {
#if 0
	      printf("  Argnum %d data %x -> offset %d (%x)\n",
		     argnum, *((int *)val), stack_offset,
		     (int) (sp + stack_offset));
#endif
	      write_memory (sp + stack_offset, val, partial_len);
	      stack_offset += align_up (partial_len, 4);
	    }
	  len -= partial_len;
	  val += partial_len;
	}
    }

  /* Set the return address.  For the frv, the return breakpoint is
     always at BP_ADDR.  */
  regcache_cooked_write_unsigned (regcache, lr_regnum, bp_addr);

  if (abi == FRV_ABI_FDPIC)
    {
      /* Set the GOT register for the FDPIC ABI.  */
      regcache_cooked_write_unsigned
	(regcache, first_gpr_regnum + 15,
         frv_fdpic_find_global_pointer (func_addr));
    }

  /* Finally, update the SP register.  */
  regcache_cooked_write_unsigned (regcache, sp_regnum, sp);

  return sp;
}

static void
frv_store_return_value (struct type *type, struct regcache *regcache,
                        const gdb_byte *valbuf)
{
  int len = TYPE_LENGTH (type);

  if (len <= 4)
    {
      bfd_byte val[4];
      memset (val, 0, sizeof (val));
      memcpy (val + (4 - len), valbuf, len);
      regcache->cooked_write (8, val);
    }
  else if (len == 8)
    {
      regcache->cooked_write (8, valbuf);
      regcache->cooked_write (9, (bfd_byte *) valbuf + 4);
    }
  else
    internal_error (__FILE__, __LINE__,
                    _("Don't know how to return a %d-byte value."), len);
}

static enum return_value_convention
frv_return_value (struct gdbarch *gdbarch, struct value *function,
		  struct type *valtype, struct regcache *regcache,
		  gdb_byte *readbuf, const gdb_byte *writebuf)
{
  int struct_return = TYPE_CODE (valtype) == TYPE_CODE_STRUCT
		      || TYPE_CODE (valtype) == TYPE_CODE_UNION
		      || TYPE_CODE (valtype) == TYPE_CODE_ARRAY;

  if (writebuf != NULL)
    {
      gdb_assert (!struct_return);
      frv_store_return_value (valtype, regcache, writebuf);
    }

  if (readbuf != NULL)
    {
      gdb_assert (!struct_return);
      frv_extract_return_value (valtype, regcache, readbuf);
    }

  if (struct_return)
    return RETURN_VALUE_STRUCT_CONVENTION;
  else
    return RETURN_VALUE_REGISTER_CONVENTION;
}

/* Given a GDB frame, determine the address of the calling function's
   frame.  This will be used to create a new GDB frame struct.  */

static void
frv_frame_this_id (struct frame_info *this_frame,
		    void **this_prologue_cache, struct frame_id *this_id)
{
  struct frv_unwind_cache *info
    = frv_frame_unwind_cache (this_frame, this_prologue_cache);
  CORE_ADDR base;
  CORE_ADDR func;
  struct bound_minimal_symbol msym_stack;
  struct frame_id id;

  /* The FUNC is easy.  */
  func = get_frame_func (this_frame);

  /* Check if the stack is empty.  */
  msym_stack = lookup_minimal_symbol ("_stack", NULL, NULL);
  if (msym_stack.minsym && info->base == BMSYMBOL_VALUE_ADDRESS (msym_stack))
    return;

  /* Hopefully the prologue analysis either correctly determined the
     frame's base (which is the SP from the previous frame), or set
     that base to "NULL".  */
  base = info->prev_sp;
  if (base == 0)
    return;

  id = frame_id_build (base, func);
  (*this_id) = id;
}

static struct value *
frv_frame_prev_register (struct frame_info *this_frame,
			 void **this_prologue_cache, int regnum)
{
  struct frv_unwind_cache *info
    = frv_frame_unwind_cache (this_frame, this_prologue_cache);
  return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
}

static const struct frame_unwind frv_frame_unwind = {
  NORMAL_FRAME,
  default_frame_unwind_stop_reason,
  frv_frame_this_id,
  frv_frame_prev_register,
  NULL,
  default_frame_sniffer
};

static CORE_ADDR
frv_frame_base_address (struct frame_info *this_frame, void **this_cache)
{
  struct frv_unwind_cache *info
    = frv_frame_unwind_cache (this_frame, this_cache);
  return info->base;
}

static const struct frame_base frv_frame_base = {
  &frv_frame_unwind,
  frv_frame_base_address,
  frv_frame_base_address,
  frv_frame_base_address
};

static struct gdbarch *
frv_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
{
  struct gdbarch *gdbarch;
  struct gdbarch_tdep *var;
  int elf_flags = 0;

  /* Check to see if we've already built an appropriate architecture
     object for this executable.  */
  arches = gdbarch_list_lookup_by_info (arches, &info);
  if (arches)
    return arches->gdbarch;

  /* Select the right tdep structure for this variant.  */
  var = new_variant ();
  switch (info.bfd_arch_info->mach)
    {
    case bfd_mach_frv:
    case bfd_mach_frvsimple:
    case bfd_mach_fr300:
    case bfd_mach_fr500:
    case bfd_mach_frvtomcat:
    case bfd_mach_fr550:
      set_variant_num_gprs (var, 64);
      set_variant_num_fprs (var, 64);
      break;

    case bfd_mach_fr400:
    case bfd_mach_fr450:
      set_variant_num_gprs (var, 32);
      set_variant_num_fprs (var, 32);
      break;

    default:
      /* Never heard of this variant.  */
      return 0;
    }

  /* Extract the ELF flags, if available.  */
  if (info.abfd && bfd_get_flavour (info.abfd) == bfd_target_elf_flavour)
    elf_flags = elf_elfheader (info.abfd)->e_flags;

  if (elf_flags & EF_FRV_FDPIC)
    set_variant_abi_fdpic (var);

  if (elf_flags & EF_FRV_CPU_FR450)
    set_variant_scratch_registers (var);

  gdbarch = gdbarch_alloc (&info, var);

  set_gdbarch_short_bit (gdbarch, 16);
  set_gdbarch_int_bit (gdbarch, 32);
  set_gdbarch_long_bit (gdbarch, 32);
  set_gdbarch_long_long_bit (gdbarch, 64);
  set_gdbarch_float_bit (gdbarch, 32);
  set_gdbarch_double_bit (gdbarch, 64);
  set_gdbarch_long_double_bit (gdbarch, 64);
  set_gdbarch_ptr_bit (gdbarch, 32);

  set_gdbarch_num_regs (gdbarch, frv_num_regs);
  set_gdbarch_num_pseudo_regs (gdbarch, frv_num_pseudo_regs);

  set_gdbarch_sp_regnum (gdbarch, sp_regnum);
  set_gdbarch_deprecated_fp_regnum (gdbarch, fp_regnum);
  set_gdbarch_pc_regnum (gdbarch, pc_regnum);

  set_gdbarch_register_name (gdbarch, frv_register_name);
  set_gdbarch_register_type (gdbarch, frv_register_type);
  set_gdbarch_register_sim_regno (gdbarch, frv_register_sim_regno);

  set_gdbarch_pseudo_register_read (gdbarch, frv_pseudo_register_read);
  set_gdbarch_pseudo_register_write (gdbarch, frv_pseudo_register_write);

  set_gdbarch_skip_prologue (gdbarch, frv_skip_prologue);
  set_gdbarch_skip_main_prologue (gdbarch, frv_skip_main_prologue);
  set_gdbarch_breakpoint_kind_from_pc (gdbarch, frv_breakpoint::kind_from_pc);
  set_gdbarch_sw_breakpoint_from_kind (gdbarch, frv_breakpoint::bp_from_kind);
  set_gdbarch_adjust_breakpoint_address
    (gdbarch, frv_adjust_breakpoint_address);

  set_gdbarch_return_value (gdbarch, frv_return_value);

  /* Frame stuff.  */
  set_gdbarch_frame_align (gdbarch, frv_frame_align);
  frame_base_set_default (gdbarch, &frv_frame_base);
  /* We set the sniffer lower down after the OSABI hooks have been
     established.  */

  /* Settings for calling functions in the inferior.  */
  set_gdbarch_push_dummy_call (gdbarch, frv_push_dummy_call);

  /* Settings that should be unnecessary.  */
  set_gdbarch_inner_than (gdbarch, core_addr_lessthan);

  /* Hardware watchpoint / breakpoint support.  */
  switch (info.bfd_arch_info->mach)
    {
    case bfd_mach_frv:
    case bfd_mach_frvsimple:
    case bfd_mach_fr300:
    case bfd_mach_fr500:
    case bfd_mach_frvtomcat:
      /* fr500-style hardware debugging support.  */
      var->num_hw_watchpoints = 4;
      var->num_hw_breakpoints = 4;
      break;

    case bfd_mach_fr400:
    case bfd_mach_fr450:
      /* fr400-style hardware debugging support.  */
      var->num_hw_watchpoints = 2;
      var->num_hw_breakpoints = 4;
      break;

    default:
      /* Otherwise, assume we don't have hardware debugging support.  */
      var->num_hw_watchpoints = 0;
      var->num_hw_breakpoints = 0;
      break;
    }

  if (frv_abi (gdbarch) == FRV_ABI_FDPIC)
    set_gdbarch_convert_from_func_ptr_addr (gdbarch,
					    frv_convert_from_func_ptr_addr);

  set_solib_ops (gdbarch, &frv_so_ops);

  /* Hook in ABI-specific overrides, if they have been registered.  */
  gdbarch_init_osabi (info, gdbarch);

  /* Set the fallback (prologue based) frame sniffer.  */
  frame_unwind_append_unwinder (gdbarch, &frv_frame_unwind);

  /* Enable TLS support.  */
  set_gdbarch_fetch_tls_load_module_address (gdbarch,
                                             frv_fetch_objfile_link_map);

  return gdbarch;
}

void
_initialize_frv_tdep (void)
{
  register_gdbarch_init (bfd_arch_frv, frv_gdbarch_init);
}