aboutsummaryrefslogtreecommitdiff
path: root/gdb/rs6000-tdep.c
blob: 6f5ade6a8c1760f7f1a9a892c72d014576981e99 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
/* Target-dependent code for GDB, the GNU debugger.
   Copyright 1986, 1987, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997,
   1998, 1999, 2000, 2001
   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 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include "defs.h"
#include "frame.h"
#include "inferior.h"
#include "symtab.h"
#include "target.h"
#include "gdbcore.h"
#include "gdbcmd.h"
#include "symfile.h"
#include "objfiles.h"
#include "arch-utils.h"
#include "regcache.h"
#include "doublest.h"

#include "bfd/libbfd.h"		/* for bfd_default_set_arch_mach */
#include "coff/internal.h"	/* for libcoff.h */
#include "bfd/libcoff.h"	/* for xcoff_data */

#include "elf-bfd.h"

#include "ppc-tdep.h"

/* If the kernel has to deliver a signal, it pushes a sigcontext
   structure on the stack and then calls the signal handler, passing
   the address of the sigcontext in an argument register. Usually
   the signal handler doesn't save this register, so we have to
   access the sigcontext structure via an offset from the signal handler
   frame.
   The following constants were determined by experimentation on AIX 3.2.  */
#define SIG_FRAME_PC_OFFSET 96
#define SIG_FRAME_LR_OFFSET 108
#define SIG_FRAME_FP_OFFSET 284

/* To be used by skip_prologue. */

struct rs6000_framedata
  {
    int offset;			/* total size of frame --- the distance
				   by which we decrement sp to allocate
				   the frame */
    int saved_gpr;		/* smallest # of saved gpr */
    int saved_fpr;		/* smallest # of saved fpr */
    int alloca_reg;		/* alloca register number (frame ptr) */
    char frameless;		/* true if frameless functions. */
    char nosavedpc;		/* true if pc not saved. */
    int gpr_offset;		/* offset of saved gprs from prev sp */
    int fpr_offset;		/* offset of saved fprs from prev sp */
    int lr_offset;		/* offset of saved lr */
    int cr_offset;		/* offset of saved cr */
  };

/* Description of a single register. */

struct reg
  {
    char *name;			/* name of register */
    unsigned char sz32;		/* size on 32-bit arch, 0 if nonextant */
    unsigned char sz64;		/* size on 64-bit arch, 0 if nonextant */
    unsigned char fpr;		/* whether register is floating-point */
  };

/* Private data that this module attaches to struct gdbarch. */

struct gdbarch_tdep
  {
    int wordsize;		/* size in bytes of fixed-point word */
    int osabi;			/* OS / ABI from ELF header */
    int *regoff;		/* byte offsets in register arrays */
    const struct reg *regs;	/* from current variant */
  };

/* Return the current architecture's gdbarch_tdep structure. */

#define TDEP	gdbarch_tdep (current_gdbarch)

/* Breakpoint shadows for the single step instructions will be kept here. */

static struct sstep_breaks
  {
    /* Address, or 0 if this is not in use.  */
    CORE_ADDR address;
    /* Shadow contents.  */
    char data[4];
  }
stepBreaks[2];

/* Hook for determining the TOC address when calling functions in the
   inferior under AIX. The initialization code in rs6000-nat.c sets
   this hook to point to find_toc_address.  */

CORE_ADDR (*rs6000_find_toc_address_hook) (CORE_ADDR) = NULL;

/* Hook to set the current architecture when starting a child process. 
   rs6000-nat.c sets this. */

void (*rs6000_set_host_arch_hook) (int) = NULL;

/* Static function prototypes */

static CORE_ADDR branch_dest (int opcode, int instr, CORE_ADDR pc,
			      CORE_ADDR safety);
static CORE_ADDR skip_prologue (CORE_ADDR, CORE_ADDR,
                                struct rs6000_framedata *);
static void frame_get_saved_regs (struct frame_info * fi,
				  struct rs6000_framedata * fdatap);
static CORE_ADDR frame_initial_stack_address (struct frame_info *);

/* Read a LEN-byte address from debugged memory address MEMADDR. */

static CORE_ADDR
read_memory_addr (CORE_ADDR memaddr, int len)
{
  return read_memory_unsigned_integer (memaddr, len);
}

static CORE_ADDR
rs6000_skip_prologue (CORE_ADDR pc)
{
  struct rs6000_framedata frame;
  pc = skip_prologue (pc, 0, &frame);
  return pc;
}


/* Fill in fi->saved_regs */

struct frame_extra_info
{
  /* Functions calling alloca() change the value of the stack
     pointer. We need to use initial stack pointer (which is saved in
     r31 by gcc) in such cases. If a compiler emits traceback table,
     then we should use the alloca register specified in traceback
     table. FIXME. */
  CORE_ADDR initial_sp;		/* initial stack pointer. */
};

void
rs6000_init_extra_frame_info (int fromleaf, struct frame_info *fi)
{
  fi->extra_info = (struct frame_extra_info *)
    frame_obstack_alloc (sizeof (struct frame_extra_info));
  fi->extra_info->initial_sp = 0;
  if (fi->next != (CORE_ADDR) 0
      && fi->pc < TEXT_SEGMENT_BASE)
    /* We're in get_prev_frame */
    /* and this is a special signal frame.  */
    /* (fi->pc will be some low address in the kernel, */
    /*  to which the signal handler returns).  */
    fi->signal_handler_caller = 1;
}

/* Put here the code to store, into a struct frame_saved_regs,
   the addresses of the saved registers of frame described by FRAME_INFO.
   This includes special registers such as pc and fp saved in special
   ways in the stack frame.  sp is even more special:
   the address we return for it IS the sp for the next frame.  */

/* In this implementation for RS/6000, we do *not* save sp. I am
   not sure if it will be needed. The following function takes care of gpr's
   and fpr's only. */

void
rs6000_frame_init_saved_regs (struct frame_info *fi)
{
  frame_get_saved_regs (fi, NULL);
}

static CORE_ADDR
rs6000_frame_args_address (struct frame_info *fi)
{
  if (fi->extra_info->initial_sp != 0)
    return fi->extra_info->initial_sp;
  else
    return frame_initial_stack_address (fi);
}

/* Immediately after a function call, return the saved pc.
   Can't go through the frames for this because on some machines
   the new frame is not set up until the new function executes
   some instructions.  */

static CORE_ADDR
rs6000_saved_pc_after_call (struct frame_info *fi)
{
  return read_register (PPC_LR_REGNUM);
}

/* Calculate the destination of a branch/jump.  Return -1 if not a branch.  */

static CORE_ADDR
branch_dest (int opcode, int instr, CORE_ADDR pc, CORE_ADDR safety)
{
  CORE_ADDR dest;
  int immediate;
  int absolute;
  int ext_op;

  absolute = (int) ((instr >> 1) & 1);

  switch (opcode)
    {
    case 18:
      immediate = ((instr & ~3) << 6) >> 6;	/* br unconditional */
      if (absolute)
	dest = immediate;
      else
	dest = pc + immediate;
      break;

    case 16:
      immediate = ((instr & ~3) << 16) >> 16;	/* br conditional */
      if (absolute)
	dest = immediate;
      else
	dest = pc + immediate;
      break;

    case 19:
      ext_op = (instr >> 1) & 0x3ff;

      if (ext_op == 16)		/* br conditional register */
	{
	  dest = read_register (PPC_LR_REGNUM) & ~3;

	  /* If we are about to return from a signal handler, dest is
	     something like 0x3c90.  The current frame is a signal handler
	     caller frame, upon completion of the sigreturn system call
	     execution will return to the saved PC in the frame.  */
	  if (dest < TEXT_SEGMENT_BASE)
	    {
	      struct frame_info *fi;

	      fi = get_current_frame ();
	      if (fi != NULL)
		dest = read_memory_addr (fi->frame + SIG_FRAME_PC_OFFSET,
					 TDEP->wordsize);
	    }
	}

      else if (ext_op == 528)	/* br cond to count reg */
	{
	  dest = read_register (PPC_CTR_REGNUM) & ~3;

	  /* If we are about to execute a system call, dest is something
	     like 0x22fc or 0x3b00.  Upon completion the system call
	     will return to the address in the link register.  */
	  if (dest < TEXT_SEGMENT_BASE)
	    dest = read_register (PPC_LR_REGNUM) & ~3;
	}
      else
	return -1;
      break;

    default:
      return -1;
    }
  return (dest < TEXT_SEGMENT_BASE) ? safety : dest;
}


/* Sequence of bytes for breakpoint instruction.  */

#define BIG_BREAKPOINT { 0x7d, 0x82, 0x10, 0x08 }
#define LITTLE_BREAKPOINT { 0x08, 0x10, 0x82, 0x7d }

static unsigned char *
rs6000_breakpoint_from_pc (CORE_ADDR *bp_addr, int *bp_size)
{
  static unsigned char big_breakpoint[] = BIG_BREAKPOINT;
  static unsigned char little_breakpoint[] = LITTLE_BREAKPOINT;
  *bp_size = 4;
  if (TARGET_BYTE_ORDER == BIG_ENDIAN)
    return big_breakpoint;
  else
    return little_breakpoint;
}


/* AIX does not support PT_STEP. Simulate it. */

void
rs6000_software_single_step (enum target_signal signal,
			     int insert_breakpoints_p)
{
#define	INSNLEN(OPCODE)	 4

  static char le_breakp[] = LITTLE_BREAKPOINT;
  static char be_breakp[] = BIG_BREAKPOINT;
  char *breakp = TARGET_BYTE_ORDER == BIG_ENDIAN ? be_breakp : le_breakp;
  int ii, insn;
  CORE_ADDR loc;
  CORE_ADDR breaks[2];
  int opcode;

  if (insert_breakpoints_p)
    {

      loc = read_pc ();

      insn = read_memory_integer (loc, 4);

      breaks[0] = loc + INSNLEN (insn);
      opcode = insn >> 26;
      breaks[1] = branch_dest (opcode, insn, loc, breaks[0]);

      /* Don't put two breakpoints on the same address. */
      if (breaks[1] == breaks[0])
	breaks[1] = -1;

      stepBreaks[1].address = 0;

      for (ii = 0; ii < 2; ++ii)
	{

	  /* ignore invalid breakpoint. */
	  if (breaks[ii] == -1)
	    continue;

	  read_memory (breaks[ii], stepBreaks[ii].data, 4);

	  write_memory (breaks[ii], breakp, 4);
	  stepBreaks[ii].address = breaks[ii];
	}

    }
  else
    {

      /* remove step breakpoints. */
      for (ii = 0; ii < 2; ++ii)
	if (stepBreaks[ii].address != 0)
	  write_memory
	    (stepBreaks[ii].address, stepBreaks[ii].data, 4);

    }
  errno = 0;			/* FIXME, don't ignore errors! */
  /* What errors?  {read,write}_memory call error().  */
}


/* return pc value after skipping a function prologue and also return
   information about a function frame.

   in struct rs6000_framedata fdata:
   - frameless is TRUE, if function does not have a frame.
   - nosavedpc is TRUE, if function does not save %pc value in its frame.
   - offset is the initial size of this stack frame --- the amount by
   which we decrement the sp to allocate the frame.
   - saved_gpr is the number of the first saved gpr.
   - saved_fpr is the number of the first saved fpr.
   - alloca_reg is the number of the register used for alloca() handling.
   Otherwise -1.
   - gpr_offset is the offset of the first saved gpr from the previous frame.
   - fpr_offset is the offset of the first saved fpr from the previous frame.
   - lr_offset is the offset of the saved lr
   - cr_offset is the offset of the saved cr
 */

#define SIGNED_SHORT(x) 						\
  ((sizeof (short) == 2)						\
   ? ((int)(short)(x))							\
   : ((int)((((x) & 0xffff) ^ 0x8000) - 0x8000)))

#define GET_SRC_REG(x) (((x) >> 21) & 0x1f)

/* Limit the number of skipped non-prologue instructions, as the examining
   of the prologue is expensive.  */
static int max_skip_non_prologue_insns = 10;

/* Given PC representing the starting address of a function, and
   LIM_PC which is the (sloppy) limit to which to scan when looking
   for a prologue, attempt to further refine this limit by using
   the line data in the symbol table.  If successful, a better guess
   on where the prologue ends is returned, otherwise the previous
   value of lim_pc is returned.  */
static CORE_ADDR
refine_prologue_limit (CORE_ADDR pc, CORE_ADDR lim_pc)
{
  struct symtab_and_line prologue_sal;

  prologue_sal = find_pc_line (pc, 0);
  if (prologue_sal.line != 0)
    {
      int i;
      CORE_ADDR addr = prologue_sal.end;

      /* Handle the case in which compiler's optimizer/scheduler
         has moved instructions into the prologue.  We scan ahead
	 in the function looking for address ranges whose corresponding
	 line number is less than or equal to the first one that we
	 found for the function.  (It can be less than when the
	 scheduler puts a body instruction before the first prologue
	 instruction.)  */
      for (i = 2 * max_skip_non_prologue_insns; 
           i > 0 && (lim_pc == 0 || addr < lim_pc);
	   i--)
        {
	  struct symtab_and_line sal;

	  sal = find_pc_line (addr, 0);
	  if (sal.line == 0)
	    break;
	  if (sal.line <= prologue_sal.line 
	      && sal.symtab == prologue_sal.symtab)
	    {
	      prologue_sal = sal;
	    }
	  addr = sal.end;
	}

      if (lim_pc == 0 || prologue_sal.end < lim_pc)
	lim_pc = prologue_sal.end;
    }
  return lim_pc;
}


static CORE_ADDR
skip_prologue (CORE_ADDR pc, CORE_ADDR lim_pc, struct rs6000_framedata *fdata)
{
  CORE_ADDR orig_pc = pc;
  CORE_ADDR last_prologue_pc = pc;
  char buf[4];
  unsigned long op;
  long offset = 0;
  int lr_reg = -1;
  int cr_reg = -1;
  int reg;
  int framep = 0;
  int minimal_toc_loaded = 0;
  int prev_insn_was_prologue_insn = 1;
  int num_skip_non_prologue_insns = 0;

  /* Attempt to find the end of the prologue when no limit is specified.
     Note that refine_prologue_limit() has been written so that it may
     be used to "refine" the limits of non-zero PC values too, but this
     is only safe if we 1) trust the line information provided by the
     compiler and 2) iterate enough to actually find the end of the
     prologue.  
     
     It may become a good idea at some point (for both performance and
     accuracy) to unconditionally call refine_prologue_limit().  But,
     until we can make a clear determination that this is beneficial,
     we'll play it safe and only use it to obtain a limit when none
     has been specified.  */
  if (lim_pc == 0)
    lim_pc = refine_prologue_limit (pc, lim_pc);

  memset (fdata, 0, sizeof (struct rs6000_framedata));
  fdata->saved_gpr = -1;
  fdata->saved_fpr = -1;
  fdata->alloca_reg = -1;
  fdata->frameless = 1;
  fdata->nosavedpc = 1;

  for (;; pc += 4)
    {
      /* Sometimes it isn't clear if an instruction is a prologue
         instruction or not.  When we encounter one of these ambiguous
	 cases, we'll set prev_insn_was_prologue_insn to 0 (false).
	 Otherwise, we'll assume that it really is a prologue instruction. */
      if (prev_insn_was_prologue_insn)
	last_prologue_pc = pc;

      /* Stop scanning if we've hit the limit.  */
      if (lim_pc != 0 && pc >= lim_pc)
	break;

      prev_insn_was_prologue_insn = 1;

      /* Fetch the instruction and convert it to an integer.  */
      if (target_read_memory (pc, buf, 4))
	break;
      op = extract_signed_integer (buf, 4);

      if ((op & 0xfc1fffff) == 0x7c0802a6)
	{			/* mflr Rx */
	  lr_reg = (op & 0x03e00000) | 0x90010000;
	  continue;

	}
      else if ((op & 0xfc1fffff) == 0x7c000026)
	{			/* mfcr Rx */
	  cr_reg = (op & 0x03e00000) | 0x90010000;
	  continue;

	}
      else if ((op & 0xfc1f0000) == 0xd8010000)
	{			/* stfd Rx,NUM(r1) */
	  reg = GET_SRC_REG (op);
	  if (fdata->saved_fpr == -1 || fdata->saved_fpr > reg)
	    {
	      fdata->saved_fpr = reg;
	      fdata->fpr_offset = SIGNED_SHORT (op) + offset;
	    }
	  continue;

	}
      else if (((op & 0xfc1f0000) == 0xbc010000) ||	/* stm Rx, NUM(r1) */
	       (((op & 0xfc1f0000) == 0x90010000 ||	/* st rx,NUM(r1) */
		 (op & 0xfc1f0003) == 0xf8010000) &&	/* std rx,NUM(r1) */
		(op & 0x03e00000) >= 0x01a00000))	/* rx >= r13 */
	{

	  reg = GET_SRC_REG (op);
	  if (fdata->saved_gpr == -1 || fdata->saved_gpr > reg)
	    {
	      fdata->saved_gpr = reg;
	      if ((op & 0xfc1f0003) == 0xf8010000)
		op = (op >> 1) << 1;
	      fdata->gpr_offset = SIGNED_SHORT (op) + offset;
	    }
	  continue;

	}
      else if ((op & 0xffff0000) == 0x60000000)
        {
	  			/* nop */
	  /* Allow nops in the prologue, but do not consider them to
	     be part of the prologue unless followed by other prologue
	     instructions. */
	  prev_insn_was_prologue_insn = 0;
	  continue;

	}
      else if ((op & 0xffff0000) == 0x3c000000)
	{			/* addis 0,0,NUM, used
				   for >= 32k frames */
	  fdata->offset = (op & 0x0000ffff) << 16;
	  fdata->frameless = 0;
	  continue;

	}
      else if ((op & 0xffff0000) == 0x60000000)
	{			/* ori 0,0,NUM, 2nd ha
				   lf of >= 32k frames */
	  fdata->offset |= (op & 0x0000ffff);
	  fdata->frameless = 0;
	  continue;

	}
      else if (lr_reg != -1 && (op & 0xffff0000) == lr_reg)
	{			/* st Rx,NUM(r1) 
				   where Rx == lr */
	  fdata->lr_offset = SIGNED_SHORT (op) + offset;
	  fdata->nosavedpc = 0;
	  lr_reg = 0;
	  continue;

	}
      else if (cr_reg != -1 && (op & 0xffff0000) == cr_reg)
	{			/* st Rx,NUM(r1) 
				   where Rx == cr */
	  fdata->cr_offset = SIGNED_SHORT (op) + offset;
	  cr_reg = 0;
	  continue;

	}
      else if (op == 0x48000005)
	{			/* bl .+4 used in 
				   -mrelocatable */
	  continue;

	}
      else if (op == 0x48000004)
	{			/* b .+4 (xlc) */
	  break;

	}
      else if (((op & 0xffff0000) == 0x801e0000 ||	/* lwz 0,NUM(r30), used
							   in V.4 -mrelocatable */
		op == 0x7fc0f214) &&	/* add r30,r0,r30, used
					   in V.4 -mrelocatable */
	       lr_reg == 0x901e0000)
	{
	  continue;

	}
      else if ((op & 0xffff0000) == 0x3fc00000 ||	/* addis 30,0,foo@ha, used
							   in V.4 -mminimal-toc */
	       (op & 0xffff0000) == 0x3bde0000)
	{			/* addi 30,30,foo@l */
	  continue;

	}
      else if ((op & 0xfc000001) == 0x48000001)
	{			/* bl foo, 
				   to save fprs??? */

	  fdata->frameless = 0;
	  /* Don't skip over the subroutine call if it is not within the first
	     three instructions of the prologue.  */
	  if ((pc - orig_pc) > 8)
	    break;

	  op = read_memory_integer (pc + 4, 4);

	  /* At this point, make sure this is not a trampoline function
	     (a function that simply calls another functions, and nothing else).
	     If the next is not a nop, this branch was part of the function
	     prologue. */

	  if (op == 0x4def7b82 || op == 0)	/* crorc 15, 15, 15 */
	    break;		/* don't skip over 
				   this branch */
	  continue;

	  /* update stack pointer */
	}
      else if ((op & 0xffff0000) == 0x94210000 ||	/* stu r1,NUM(r1) */
	       (op & 0xffff0003) == 0xf8210001)		/* stdu r1,NUM(r1) */
	{
	  fdata->frameless = 0;
	  if ((op & 0xffff0003) == 0xf8210001)
	    op = (op >> 1) << 1;
	  fdata->offset = SIGNED_SHORT (op);
	  offset = fdata->offset;
	  continue;

	}
      else if (op == 0x7c21016e)
	{			/* stwux 1,1,0 */
	  fdata->frameless = 0;
	  offset = fdata->offset;
	  continue;

	  /* Load up minimal toc pointer */
	}
      else if ((op >> 22) == 0x20f
	       && !minimal_toc_loaded)
	{			/* l r31,... or l r30,... */
	  minimal_toc_loaded = 1;
	  continue;

	  /* move parameters from argument registers to local variable
             registers */
 	}
      else if ((op & 0xfc0007fe) == 0x7c000378 &&	/* mr(.)  Rx,Ry */
               (((op >> 21) & 31) >= 3) &&              /* R3 >= Ry >= R10 */
               (((op >> 21) & 31) <= 10) &&
               (((op >> 16) & 31) >= fdata->saved_gpr)) /* Rx: local var reg */
	{
	  continue;

	  /* store parameters in stack */
	}
      else if ((op & 0xfc1f0000) == 0x90010000 ||	/* st rx,NUM(r1) */
	       (op & 0xfc1f0003) == 0xf8010000 ||	/* std rx,NUM(r1) */
	       (op & 0xfc1f0000) == 0xd8010000 ||	/* stfd Rx,NUM(r1) */
	       (op & 0xfc1f0000) == 0xfc010000)		/* frsp, fp?,NUM(r1) */
	{
	  continue;

	  /* store parameters in stack via frame pointer */
	}
      else if (framep &&
	       ((op & 0xfc1f0000) == 0x901f0000 ||	/* st rx,NUM(r1) */
		(op & 0xfc1f0000) == 0xd81f0000 ||	/* stfd Rx,NUM(r1) */
		(op & 0xfc1f0000) == 0xfc1f0000))
	{			/* frsp, fp?,NUM(r1) */
	  continue;

	  /* Set up frame pointer */
	}
      else if (op == 0x603f0000	/* oril r31, r1, 0x0 */
	       || op == 0x7c3f0b78)
	{			/* mr r31, r1 */
	  fdata->frameless = 0;
	  framep = 1;
	  fdata->alloca_reg = 31;
	  continue;

	  /* Another way to set up the frame pointer.  */
	}
      else if ((op & 0xfc1fffff) == 0x38010000)
	{			/* addi rX, r1, 0x0 */
	  fdata->frameless = 0;
	  framep = 1;
	  fdata->alloca_reg = (op & ~0x38010000) >> 21;
	  continue;

	}
      else
	{
	  /* Not a recognized prologue instruction.
	     Handle optimizer code motions into the prologue by continuing
	     the search if we have no valid frame yet or if the return
	     address is not yet saved in the frame.  */
	  if (fdata->frameless == 0
	      && (lr_reg == -1 || fdata->nosavedpc == 0))
	    break;

	  if (op == 0x4e800020		/* blr */
	      || op == 0x4e800420)	/* bctr */
	    /* Do not scan past epilogue in frameless functions or
	       trampolines.  */
	    break;
	  if ((op & 0xf4000000) == 0x40000000) /* bxx */
	    /* Never skip branches. */
	    break;

	  if (num_skip_non_prologue_insns++ > max_skip_non_prologue_insns)
	    /* Do not scan too many insns, scanning insns is expensive with
	       remote targets.  */
	    break;

	  /* Continue scanning.  */
	  prev_insn_was_prologue_insn = 0;
	  continue;
	}
    }

#if 0
/* I have problems with skipping over __main() that I need to address
 * sometime. Previously, I used to use misc_function_vector which
 * didn't work as well as I wanted to be.  -MGO */

  /* If the first thing after skipping a prolog is a branch to a function,
     this might be a call to an initializer in main(), introduced by gcc2.
     We'd like to skip over it as well. Fortunately, xlc does some extra
     work before calling a function right after a prologue, thus we can
     single out such gcc2 behaviour. */


  if ((op & 0xfc000001) == 0x48000001)
    {				/* bl foo, an initializer function? */
      op = read_memory_integer (pc + 4, 4);

      if (op == 0x4def7b82)
	{			/* cror 0xf, 0xf, 0xf (nop) */

	  /* check and see if we are in main. If so, skip over this initializer
	     function as well. */

	  tmp = find_pc_misc_function (pc);
	  if (tmp >= 0 && STREQ (misc_function_vector[tmp].name, main_name ()))
	    return pc + 8;
	}
    }
#endif /* 0 */

  fdata->offset = -fdata->offset;
  return last_prologue_pc;
}


/*************************************************************************
  Support for creating pushing a dummy frame into the stack, and popping
  frames, etc. 
*************************************************************************/


/* Pop the innermost frame, go back to the caller. */

static void
rs6000_pop_frame (void)
{
  CORE_ADDR pc, lr, sp, prev_sp, addr;	/* %pc, %lr, %sp */
  struct rs6000_framedata fdata;
  struct frame_info *frame = get_current_frame ();
  int ii, wordsize;

  pc = read_pc ();
  sp = FRAME_FP (frame);

  if (PC_IN_CALL_DUMMY (frame->pc, frame->frame, frame->frame))
    {
      generic_pop_dummy_frame ();
      flush_cached_frames ();
      return;
    }

  /* Make sure that all registers are valid.  */
  read_register_bytes (0, NULL, REGISTER_BYTES);

  /* figure out previous %pc value. If the function is frameless, it is 
     still in the link register, otherwise walk the frames and retrieve the
     saved %pc value in the previous frame. */

  addr = get_pc_function_start (frame->pc);
  (void) skip_prologue (addr, frame->pc, &fdata);

  wordsize = TDEP->wordsize;
  if (fdata.frameless)
    prev_sp = sp;
  else
    prev_sp = read_memory_addr (sp, wordsize);
  if (fdata.lr_offset == 0)
    lr = read_register (PPC_LR_REGNUM);
  else
    lr = read_memory_addr (prev_sp + fdata.lr_offset, wordsize);

  /* reset %pc value. */
  write_register (PC_REGNUM, lr);

  /* reset register values if any was saved earlier. */

  if (fdata.saved_gpr != -1)
    {
      addr = prev_sp + fdata.gpr_offset;
      for (ii = fdata.saved_gpr; ii <= 31; ++ii)
	{
	  read_memory (addr, &registers[REGISTER_BYTE (ii)], wordsize);
	  addr += wordsize;
	}
    }

  if (fdata.saved_fpr != -1)
    {
      addr = prev_sp + fdata.fpr_offset;
      for (ii = fdata.saved_fpr; ii <= 31; ++ii)
	{
	  read_memory (addr, &registers[REGISTER_BYTE (ii + FP0_REGNUM)], 8);
	  addr += 8;
	}
    }

  write_register (SP_REGNUM, prev_sp);
  target_store_registers (-1);
  flush_cached_frames ();
}

/* Fixup the call sequence of a dummy function, with the real function
   address.  Its arguments will be passed by gdb. */

static void
rs6000_fix_call_dummy (char *dummyname, CORE_ADDR pc, CORE_ADDR fun,
		       int nargs, struct value **args, struct type *type,
		       int gcc_p)
{
#define	TOC_ADDR_OFFSET		20
#define	TARGET_ADDR_OFFSET	28

  int ii;
  CORE_ADDR target_addr;

  if (rs6000_find_toc_address_hook != NULL)
    {
      CORE_ADDR tocvalue = (*rs6000_find_toc_address_hook) (fun);
      write_register (PPC_TOC_REGNUM, tocvalue);
    }
}

/* Pass the arguments in either registers, or in the stack. In RS/6000,
   the first eight words of the argument list (that might be less than
   eight parameters if some parameters occupy more than one word) are
   passed in r3..r10 registers.  float and double parameters are
   passed in fpr's, in addition to that. Rest of the parameters if any
   are passed in user stack. There might be cases in which half of the
   parameter is copied into registers, the other half is pushed into
   stack.

   Stack must be aligned on 64-bit boundaries when synthesizing
   function calls.

   If the function is returning a structure, then the return address is passed
   in r3, then the first 7 words of the parameters can be passed in registers,
   starting from r4. */

static CORE_ADDR
rs6000_push_arguments (int nargs, struct value **args, CORE_ADDR sp,
		       int struct_return, CORE_ADDR struct_addr)
{
  int ii;
  int len = 0;
  int argno;			/* current argument number */
  int argbytes;			/* current argument byte */
  char tmp_buffer[50];
  int f_argno = 0;		/* current floating point argno */
  int wordsize = TDEP->wordsize;

  struct value *arg = 0;
  struct type *type;

  CORE_ADDR saved_sp;

  /* The first eight words of ther arguments are passed in registers. Copy
     them appropriately.

     If the function is returning a `struct', then the first word (which 
     will be passed in r3) is used for struct return address. In that
     case we should advance one word and start from r4 register to copy 
     parameters. */

  ii = struct_return ? 1 : 0;

/* 
   effectively indirect call... gcc does...

   return_val example( float, int);

   eabi: 
   float in fp0, int in r3
   offset of stack on overflow 8/16
   for varargs, must go by type.
   power open:
   float in r3&r4, int in r5
   offset of stack on overflow different 
   both: 
   return in r3 or f0.  If no float, must study how gcc emulates floats;
   pay attention to arg promotion.  
   User may have to cast\args to handle promotion correctly 
   since gdb won't know if prototype supplied or not.
 */

  for (argno = 0, argbytes = 0; argno < nargs && ii < 8; ++ii)
    {
      int reg_size = REGISTER_RAW_SIZE (ii + 3);

      arg = args[argno];
      type = check_typedef (VALUE_TYPE (arg));
      len = TYPE_LENGTH (type);

      if (TYPE_CODE (type) == TYPE_CODE_FLT)
	{

	  /* floating point arguments are passed in fpr's, as well as gpr's.
	     There are 13 fpr's reserved for passing parameters. At this point
	     there is no way we would run out of them. */

	  if (len > 8)
	    printf_unfiltered (
				"Fatal Error: a floating point parameter #%d with a size > 8 is found!\n", argno);

	  memcpy (&registers[REGISTER_BYTE (FP0_REGNUM + 1 + f_argno)],
		  VALUE_CONTENTS (arg),
		  len);
	  ++f_argno;
	}

      if (len > reg_size)
	{

	  /* Argument takes more than one register. */
	  while (argbytes < len)
	    {
	      memset (&registers[REGISTER_BYTE (ii + 3)], 0, reg_size);
	      memcpy (&registers[REGISTER_BYTE (ii + 3)],
		      ((char *) VALUE_CONTENTS (arg)) + argbytes,
		      (len - argbytes) > reg_size
		        ? reg_size : len - argbytes);
	      ++ii, argbytes += reg_size;

	      if (ii >= 8)
		goto ran_out_of_registers_for_arguments;
	    }
	  argbytes = 0;
	  --ii;
	}
      else
	{			/* Argument can fit in one register. No problem. */
	  int adj = TARGET_BYTE_ORDER == BIG_ENDIAN ? reg_size - len : 0;
	  memset (&registers[REGISTER_BYTE (ii + 3)], 0, reg_size);
	  memcpy ((char *)&registers[REGISTER_BYTE (ii + 3)] + adj, 
	          VALUE_CONTENTS (arg), len);
	}
      ++argno;
    }

ran_out_of_registers_for_arguments:

  saved_sp = read_sp ();
#ifndef ELF_OBJECT_FORMAT
  /* location for 8 parameters are always reserved. */
  sp -= wordsize * 8;

  /* another six words for back chain, TOC register, link register, etc. */
  sp -= wordsize * 6;

  /* stack pointer must be quadword aligned */
  sp &= -16;
#endif

  /* if there are more arguments, allocate space for them in 
     the stack, then push them starting from the ninth one. */

  if ((argno < nargs) || argbytes)
    {
      int space = 0, jj;

      if (argbytes)
	{
	  space += ((len - argbytes + 3) & -4);
	  jj = argno + 1;
	}
      else
	jj = argno;

      for (; jj < nargs; ++jj)
	{
	  struct value *val = args[jj];
	  space += ((TYPE_LENGTH (VALUE_TYPE (val))) + 3) & -4;
	}

      /* add location required for the rest of the parameters */
      space = (space + 15) & -16;
      sp -= space;

      /* This is another instance we need to be concerned about securing our
         stack space. If we write anything underneath %sp (r1), we might conflict
         with the kernel who thinks he is free to use this area. So, update %sp
         first before doing anything else. */

      write_register (SP_REGNUM, sp);

      /* if the last argument copied into the registers didn't fit there 
         completely, push the rest of it into stack. */

      if (argbytes)
	{
	  write_memory (sp + 24 + (ii * 4),
			((char *) VALUE_CONTENTS (arg)) + argbytes,
			len - argbytes);
	  ++argno;
	  ii += ((len - argbytes + 3) & -4) / 4;
	}

      /* push the rest of the arguments into stack. */
      for (; argno < nargs; ++argno)
	{

	  arg = args[argno];
	  type = check_typedef (VALUE_TYPE (arg));
	  len = TYPE_LENGTH (type);


	  /* float types should be passed in fpr's, as well as in the stack. */
	  if (TYPE_CODE (type) == TYPE_CODE_FLT && f_argno < 13)
	    {

	      if (len > 8)
		printf_unfiltered (
				    "Fatal Error: a floating point parameter #%d with a size > 8 is found!\n", argno);

	      memcpy (&registers[REGISTER_BYTE (FP0_REGNUM + 1 + f_argno)],
		      VALUE_CONTENTS (arg),
		      len);
	      ++f_argno;
	    }

	  write_memory (sp + 24 + (ii * 4), (char *) VALUE_CONTENTS (arg), len);
	  ii += ((len + 3) & -4) / 4;
	}
    }
  else
    /* Secure stack areas first, before doing anything else. */
    write_register (SP_REGNUM, sp);

  /* set back chain properly */
  store_address (tmp_buffer, 4, saved_sp);
  write_memory (sp, tmp_buffer, 4);

  target_store_registers (-1);
  return sp;
}

/* Function: ppc_push_return_address (pc, sp)
   Set up the return address for the inferior function call. */

static CORE_ADDR
ppc_push_return_address (CORE_ADDR pc, CORE_ADDR sp)
{
  write_register (PPC_LR_REGNUM, CALL_DUMMY_ADDRESS ());
  return sp;
}

/* Extract a function return value of type TYPE from raw register array
   REGBUF, and copy that return value into VALBUF in virtual format. */

static void
rs6000_extract_return_value (struct type *valtype, char *regbuf, char *valbuf)
{
  int offset = 0;

  if (TYPE_CODE (valtype) == TYPE_CODE_FLT)
    {

      double dd;
      float ff;
      /* floats and doubles are returned in fpr1. fpr's have a size of 8 bytes.
         We need to truncate the return value into float size (4 byte) if
         necessary. */

      if (TYPE_LENGTH (valtype) > 4)	/* this is a double */
	memcpy (valbuf,
		&regbuf[REGISTER_BYTE (FP0_REGNUM + 1)],
		TYPE_LENGTH (valtype));
      else
	{			/* float */
	  memcpy (&dd, &regbuf[REGISTER_BYTE (FP0_REGNUM + 1)], 8);
	  ff = (float) dd;
	  memcpy (valbuf, &ff, sizeof (float));
	}
    }
  else
    {
      /* return value is copied starting from r3. */
      if (TARGET_BYTE_ORDER == BIG_ENDIAN
	  && TYPE_LENGTH (valtype) < REGISTER_RAW_SIZE (3))
	offset = REGISTER_RAW_SIZE (3) - TYPE_LENGTH (valtype);

      memcpy (valbuf,
	      regbuf + REGISTER_BYTE (3) + offset,
	      TYPE_LENGTH (valtype));
    }
}

/* Keep structure return address in this variable.
   FIXME:  This is a horrid kludge which should not be allowed to continue
   living.  This only allows a single nested call to a structure-returning
   function.  Come on, guys!  -- gnu@cygnus.com, Aug 92  */

static CORE_ADDR rs6000_struct_return_address;

/* Return whether handle_inferior_event() should proceed through code
   starting at PC in function NAME when stepping.

   The AIX -bbigtoc linker option generates functions @FIX0, @FIX1, etc. to
   handle memory references that are too distant to fit in instructions
   generated by the compiler.  For example, if 'foo' in the following
   instruction:

     lwz r9,foo(r2)

   is greater than 32767, the linker might replace the lwz with a branch to
   somewhere in @FIX1 that does the load in 2 instructions and then branches
   back to where execution should continue.

   GDB should silently step over @FIX code, just like AIX dbx does.
   Unfortunately, the linker uses the "b" instruction for the branches,
   meaning that the link register doesn't get set.  Therefore, GDB's usual
   step_over_function() mechanism won't work.

   Instead, use the IN_SOLIB_RETURN_TRAMPOLINE and SKIP_TRAMPOLINE_CODE hooks
   in handle_inferior_event() to skip past @FIX code.  */

int
rs6000_in_solib_return_trampoline (CORE_ADDR pc, char *name)
{
  return name && !strncmp (name, "@FIX", 4);
}

/* Skip code that the user doesn't want to see when stepping:

   1. Indirect function calls use a piece of trampoline code to do context
   switching, i.e. to set the new TOC table.  Skip such code if we are on
   its first instruction (as when we have single-stepped to here).

   2. Skip shared library trampoline code (which is different from
   indirect function call trampolines).

   3. Skip bigtoc fixup code.

   Result is desired PC to step until, or NULL if we are not in
   code that should be skipped.  */

CORE_ADDR
rs6000_skip_trampoline_code (CORE_ADDR pc)
{
  register unsigned int ii, op;
  int rel;
  CORE_ADDR solib_target_pc;
  struct minimal_symbol *msymbol;

  static unsigned trampoline_code[] =
  {
    0x800b0000,			/*     l   r0,0x0(r11)  */
    0x90410014,			/*    st   r2,0x14(r1)  */
    0x7c0903a6,			/* mtctr   r0           */
    0x804b0004,			/*     l   r2,0x4(r11)  */
    0x816b0008,			/*     l  r11,0x8(r11)  */
    0x4e800420,			/*  bctr                */
    0x4e800020,			/*    br                */
    0
  };

  /* Check for bigtoc fixup code.  */
  msymbol = lookup_minimal_symbol_by_pc (pc);
  if (msymbol && rs6000_in_solib_return_trampoline (pc, SYMBOL_NAME (msymbol)))
    {
      /* Double-check that the third instruction from PC is relative "b".  */
      op = read_memory_integer (pc + 8, 4);
      if ((op & 0xfc000003) == 0x48000000)
	{
	  /* Extract bits 6-29 as a signed 24-bit relative word address and
	     add it to the containing PC.  */
	  rel = ((int)(op << 6) >> 6);
	  return pc + 8 + rel;
	}
    }

  /* If pc is in a shared library trampoline, return its target.  */
  solib_target_pc = find_solib_trampoline_target (pc);
  if (solib_target_pc)
    return solib_target_pc;

  for (ii = 0; trampoline_code[ii]; ++ii)
    {
      op = read_memory_integer (pc + (ii * 4), 4);
      if (op != trampoline_code[ii])
	return 0;
    }
  ii = read_register (11);	/* r11 holds destination addr   */
  pc = read_memory_addr (ii, TDEP->wordsize); /* (r11) value */
  return pc;
}

/* Determines whether the function FI has a frame on the stack or not.  */

int
rs6000_frameless_function_invocation (struct frame_info *fi)
{
  CORE_ADDR func_start;
  struct rs6000_framedata fdata;

  /* Don't even think about framelessness except on the innermost frame
     or if the function was interrupted by a signal.  */
  if (fi->next != NULL && !fi->next->signal_handler_caller)
    return 0;

  func_start = get_pc_function_start (fi->pc);

  /* If we failed to find the start of the function, it is a mistake
     to inspect the instructions. */

  if (!func_start)
    {
      /* A frame with a zero PC is usually created by dereferencing a NULL
         function pointer, normally causing an immediate core dump of the
         inferior. Mark function as frameless, as the inferior has no chance
         of setting up a stack frame.  */
      if (fi->pc == 0)
	return 1;
      else
	return 0;
    }

  (void) skip_prologue (func_start, fi->pc, &fdata);
  return fdata.frameless;
}

/* Return the PC saved in a frame */

CORE_ADDR
rs6000_frame_saved_pc (struct frame_info *fi)
{
  CORE_ADDR func_start;
  struct rs6000_framedata fdata;
  int wordsize = TDEP->wordsize;

  if (fi->signal_handler_caller)
    return read_memory_addr (fi->frame + SIG_FRAME_PC_OFFSET, wordsize);

  if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame))
    return generic_read_register_dummy (fi->pc, fi->frame, PC_REGNUM);

  func_start = get_pc_function_start (fi->pc);

  /* If we failed to find the start of the function, it is a mistake
     to inspect the instructions. */
  if (!func_start)
    return 0;

  (void) skip_prologue (func_start, fi->pc, &fdata);

  if (fdata.lr_offset == 0 && fi->next != NULL)
    {
      if (fi->next->signal_handler_caller)
	return read_memory_addr (fi->next->frame + SIG_FRAME_LR_OFFSET,
				 wordsize);
      else
	return read_memory_addr (FRAME_CHAIN (fi) + DEFAULT_LR_SAVE,
				 wordsize);
    }

  if (fdata.lr_offset == 0)
    return read_register (PPC_LR_REGNUM);

  return read_memory_addr (FRAME_CHAIN (fi) + fdata.lr_offset, wordsize);
}

/* If saved registers of frame FI are not known yet, read and cache them.
   &FDATAP contains rs6000_framedata; TDATAP can be NULL,
   in which case the framedata are read.  */

static void
frame_get_saved_regs (struct frame_info *fi, struct rs6000_framedata *fdatap)
{
  CORE_ADDR frame_addr;
  struct rs6000_framedata work_fdata;
  int wordsize = TDEP->wordsize;

  if (fi->saved_regs)
    return;

  if (fdatap == NULL)
    {
      fdatap = &work_fdata;
      (void) skip_prologue (get_pc_function_start (fi->pc), fi->pc, fdatap);
    }

  frame_saved_regs_zalloc (fi);

  /* If there were any saved registers, figure out parent's stack
     pointer. */
  /* The following is true only if the frame doesn't have a call to
     alloca(), FIXME. */

  if (fdatap->saved_fpr == 0 && fdatap->saved_gpr == 0
      && fdatap->lr_offset == 0 && fdatap->cr_offset == 0)
    frame_addr = 0;
  else if (fi->prev && fi->prev->frame)
    frame_addr = fi->prev->frame;
  else
    frame_addr = read_memory_addr (fi->frame, wordsize);

  /* if != -1, fdatap->saved_fpr is the smallest number of saved_fpr.
     All fpr's from saved_fpr to fp31 are saved.  */

  if (fdatap->saved_fpr >= 0)
    {
      int i;
      CORE_ADDR fpr_addr = frame_addr + fdatap->fpr_offset;
      for (i = fdatap->saved_fpr; i < 32; i++)
	{
	  fi->saved_regs[FP0_REGNUM + i] = fpr_addr;
	  fpr_addr += 8;
	}
    }

  /* if != -1, fdatap->saved_gpr is the smallest number of saved_gpr.
     All gpr's from saved_gpr to gpr31 are saved.  */

  if (fdatap->saved_gpr >= 0)
    {
      int i;
      CORE_ADDR gpr_addr = frame_addr + fdatap->gpr_offset;
      for (i = fdatap->saved_gpr; i < 32; i++)
	{
	  fi->saved_regs[i] = gpr_addr;
	  gpr_addr += wordsize;
	}
    }

  /* If != 0, fdatap->cr_offset is the offset from the frame that holds
     the CR.  */
  if (fdatap->cr_offset != 0)
    fi->saved_regs[PPC_CR_REGNUM] = frame_addr + fdatap->cr_offset;

  /* If != 0, fdatap->lr_offset is the offset from the frame that holds
     the LR.  */
  if (fdatap->lr_offset != 0)
    fi->saved_regs[PPC_LR_REGNUM] = frame_addr + fdatap->lr_offset;
}

/* Return the address of a frame. This is the inital %sp value when the frame
   was first allocated. For functions calling alloca(), it might be saved in
   an alloca register. */

static CORE_ADDR
frame_initial_stack_address (struct frame_info *fi)
{
  CORE_ADDR tmpaddr;
  struct rs6000_framedata fdata;
  struct frame_info *callee_fi;

  /* if the initial stack pointer (frame address) of this frame is known,
     just return it. */

  if (fi->extra_info->initial_sp)
    return fi->extra_info->initial_sp;

  /* find out if this function is using an alloca register.. */

  (void) skip_prologue (get_pc_function_start (fi->pc), fi->pc, &fdata);

  /* if saved registers of this frame are not known yet, read and cache them. */

  if (!fi->saved_regs)
    frame_get_saved_regs (fi, &fdata);

  /* If no alloca register used, then fi->frame is the value of the %sp for
     this frame, and it is good enough. */

  if (fdata.alloca_reg < 0)
    {
      fi->extra_info->initial_sp = fi->frame;
      return fi->extra_info->initial_sp;
    }

  /* This function has an alloca register. If this is the top-most frame
     (with the lowest address), the value in alloca register is good. */

  if (!fi->next)
    return fi->extra_info->initial_sp = read_register (fdata.alloca_reg);

  /* Otherwise, this is a caller frame. Callee has usually already saved
     registers, but there are exceptions (such as when the callee
     has no parameters). Find the address in which caller's alloca
     register is saved. */

  for (callee_fi = fi->next; callee_fi; callee_fi = callee_fi->next)
    {

      if (!callee_fi->saved_regs)
	frame_get_saved_regs (callee_fi, NULL);

      /* this is the address in which alloca register is saved. */

      tmpaddr = callee_fi->saved_regs[fdata.alloca_reg];
      if (tmpaddr)
	{
	  fi->extra_info->initial_sp =
	    read_memory_addr (tmpaddr, TDEP->wordsize);
	  return fi->extra_info->initial_sp;
	}

      /* Go look into deeper levels of the frame chain to see if any one of
         the callees has saved alloca register. */
    }

  /* If alloca register was not saved, by the callee (or any of its callees)
     then the value in the register is still good. */

  fi->extra_info->initial_sp = read_register (fdata.alloca_reg);
  return fi->extra_info->initial_sp;
}

/* Describe the pointer in each stack frame to the previous stack frame
   (its caller).  */

/* FRAME_CHAIN takes a frame's nominal address
   and produces the frame's chain-pointer. */

/* In the case of the RS/6000, the frame's nominal address
   is the address of a 4-byte word containing the calling frame's address.  */

CORE_ADDR
rs6000_frame_chain (struct frame_info *thisframe)
{
  CORE_ADDR fp, fpp, lr;
  int wordsize = TDEP->wordsize;

  if (PC_IN_CALL_DUMMY (thisframe->pc, thisframe->frame, thisframe->frame))
    return thisframe->frame;	/* dummy frame same as caller's frame */

  if (inside_entry_file (thisframe->pc) ||
      thisframe->pc == entry_point_address ())
    return 0;

  if (thisframe->signal_handler_caller)
    fp = read_memory_addr (thisframe->frame + SIG_FRAME_FP_OFFSET,
			      wordsize);
  else if (thisframe->next != NULL
	   && thisframe->next->signal_handler_caller
	   && FRAMELESS_FUNCTION_INVOCATION (thisframe))
    /* A frameless function interrupted by a signal did not change the
       frame pointer.  */
    fp = FRAME_FP (thisframe);
  else
    fp = read_memory_addr ((thisframe)->frame, wordsize);

  lr = read_register (PPC_LR_REGNUM);
  if (lr == entry_point_address ())
    if (fp != 0 && (fpp = read_memory_addr (fp, wordsize)) != 0)
      if (PC_IN_CALL_DUMMY (lr, fpp, fpp))
	return fpp;

  return fp;
}

/* Return the size of register REG when words are WORDSIZE bytes long.  If REG
   isn't available with that word size, return 0. */

static int
regsize (const struct reg *reg, int wordsize)
{
  return wordsize == 8 ? reg->sz64 : reg->sz32;
}

/* Return the name of register number N, or null if no such register exists
   in the current architecture. */

static char *
rs6000_register_name (int n)
{
  struct gdbarch_tdep *tdep = TDEP;
  const struct reg *reg = tdep->regs + n;

  if (!regsize (reg, tdep->wordsize))
    return NULL;
  return reg->name;
}

/* Index within `registers' of the first byte of the space for
   register N.  */

static int
rs6000_register_byte (int n)
{
  return TDEP->regoff[n];
}

/* Return the number of bytes of storage in the actual machine representation
   for register N if that register is available, else return 0. */

static int
rs6000_register_raw_size (int n)
{
  struct gdbarch_tdep *tdep = TDEP;
  const struct reg *reg = tdep->regs + n;
  return regsize (reg, tdep->wordsize);
}

/* Number of bytes of storage in the program's representation
   for register N.  */

static int
rs6000_register_virtual_size (int n)
{
  return TYPE_LENGTH (REGISTER_VIRTUAL_TYPE (n));
}

/* Return the GDB type object for the "standard" data type
   of data in register N.  */

static struct type *
rs6000_register_virtual_type (int n)
{
  struct gdbarch_tdep *tdep = TDEP;
  const struct reg *reg = tdep->regs + n;

  return reg->fpr ? builtin_type_double :
    regsize (reg, tdep->wordsize) == 8 ? builtin_type_int64 :
      builtin_type_int32;
}

/* For the PowerPC, it appears that the debug info marks float parameters as
   floats regardless of whether the function is prototyped, but the actual
   values are always passed in as doubles.  Tell gdb to always assume that
   floats are passed as doubles and then converted in the callee. */

static int
rs6000_coerce_float_to_double (struct type *formal, struct type *actual)
{
  return 1;
}

/* Return whether register N requires conversion when moving from raw format
   to virtual format.

   The register format for RS/6000 floating point registers is always
   double, we need a conversion if the memory format is float. */

static int
rs6000_register_convertible (int n)
{
  const struct reg *reg = TDEP->regs + n;
  return reg->fpr;
}

/* Convert data from raw format for register N in buffer FROM
   to virtual format with type TYPE in buffer TO. */

static void
rs6000_register_convert_to_virtual (int n, struct type *type,
				    char *from, char *to)
{
  if (TYPE_LENGTH (type) != REGISTER_RAW_SIZE (n))
    {
      double val = extract_floating (from, REGISTER_RAW_SIZE (n));
      store_floating (to, TYPE_LENGTH (type), val);
    }
  else
    memcpy (to, from, REGISTER_RAW_SIZE (n));
}

/* Convert data from virtual format with type TYPE in buffer FROM
   to raw format for register N in buffer TO. */

static void
rs6000_register_convert_to_raw (struct type *type, int n,
				char *from, char *to)
{
  if (TYPE_LENGTH (type) != REGISTER_RAW_SIZE (n))
    {
      double val = extract_floating (from, TYPE_LENGTH (type));
      store_floating (to, REGISTER_RAW_SIZE (n), val);
    }
  else
    memcpy (to, from, REGISTER_RAW_SIZE (n));
}

/* Store the address of the place in which to copy the structure the
   subroutine will return.  This is called from call_function.

   In RS/6000, struct return addresses are passed as an extra parameter in r3.
   In function return, callee is not responsible of returning this address
   back.  Since gdb needs to find it, we will store in a designated variable
   `rs6000_struct_return_address'. */

static void
rs6000_store_struct_return (CORE_ADDR addr, CORE_ADDR sp)
{
  write_register (3, addr);
  rs6000_struct_return_address = addr;
}

/* Write into appropriate registers a function return value
   of type TYPE, given in virtual format.  */

static void
rs6000_store_return_value (struct type *type, char *valbuf)
{
  if (TYPE_CODE (type) == TYPE_CODE_FLT)

    /* Floating point values are returned starting from FPR1 and up.
       Say a double_double_double type could be returned in
       FPR1/FPR2/FPR3 triple. */

    write_register_bytes (REGISTER_BYTE (FP0_REGNUM + 1), valbuf,
			  TYPE_LENGTH (type));
  else
    /* Everything else is returned in GPR3 and up. */
    write_register_bytes (REGISTER_BYTE (PPC_GP0_REGNUM + 3), valbuf,
			  TYPE_LENGTH (type));
}

/* Extract from an array REGBUF containing the (raw) register state
   the address in which a function should return its structure value,
   as a CORE_ADDR (or an expression that can be used as one).  */

static CORE_ADDR
rs6000_extract_struct_value_address (char *regbuf)
{
  return rs6000_struct_return_address;
}

/* Return whether PC is in a dummy function call.

   FIXME: This just checks for the end of the stack, which is broken
   for things like stepping through gcc nested function stubs. */

static int
rs6000_pc_in_call_dummy (CORE_ADDR pc, CORE_ADDR sp, CORE_ADDR fp)
{
  return sp < pc && pc < fp;
}

/* Hook called when a new child process is started. */

void
rs6000_create_inferior (int pid)
{
  if (rs6000_set_host_arch_hook)
    rs6000_set_host_arch_hook (pid);
}

/* Support for CONVERT_FROM_FUNC_PTR_ADDR(ADDR).

   Usually a function pointer's representation is simply the address
   of the function. On the RS/6000 however, a function pointer is
   represented by a pointer to a TOC entry. This TOC entry contains
   three words, the first word is the address of the function, the
   second word is the TOC pointer (r2), and the third word is the
   static chain value.  Throughout GDB it is currently assumed that a
   function pointer contains the address of the function, which is not
   easy to fix.  In addition, the conversion of a function address to
   a function pointer would require allocation of a TOC entry in the
   inferior's memory space, with all its drawbacks.  To be able to
   call C++ virtual methods in the inferior (which are called via
   function pointers), find_function_addr uses this function to get the
   function address from a function pointer.  */

/* Return real function address if ADDR (a function pointer) is in the data
   space and is therefore a special function pointer.  */

CORE_ADDR
rs6000_convert_from_func_ptr_addr (CORE_ADDR addr)
{
  struct obj_section *s;

  s = find_pc_section (addr);
  if (s && s->the_bfd_section->flags & SEC_CODE)
    return addr;

  /* ADDR is in the data space, so it's a special function pointer. */
  return read_memory_addr (addr, TDEP->wordsize);
}


/* Handling the various POWER/PowerPC variants.  */


/* The arrays here called registers_MUMBLE hold information about available
   registers.

   For each family of PPC variants, I've tried to isolate out the
   common registers and put them up front, so that as long as you get
   the general family right, GDB will correctly identify the registers
   common to that family.  The common register sets are:

   For the 60x family: hid0 hid1 iabr dabr pir

   For the 505 and 860 family: eie eid nri

   For the 403 and 403GC: icdbdr esr dear evpr cdbcr tsr tcr pit tbhi
   tblo srr2 srr3 dbsr dbcr iac1 iac2 dac1 dac2 dccr iccr pbl1
   pbu1 pbl2 pbu2

   Most of these register groups aren't anything formal.  I arrived at
   them by looking at the registers that occurred in more than one
   processor. */

/* Convenience macros for populating register arrays. */

/* Within another macro, convert S to a string. */

#define STR(s)	#s

/* Return a struct reg defining register NAME that's 32 bits on 32-bit systems
   and 64 bits on 64-bit systems. */
#define R(name)		{ STR(name), 4, 8, 0 }

/* Return a struct reg defining register NAME that's 32 bits on all
   systems. */
#define R4(name)	{ STR(name), 4, 4, 0 }

/* Return a struct reg defining register NAME that's 64 bits on all
   systems. */
#define R8(name)	{ STR(name), 8, 8, 0 }

/* Return a struct reg defining floating-point register NAME. */
#define F(name)		{ STR(name), 8, 8, 1 }

/* Return a struct reg defining register NAME that's 32 bits on 32-bit
   systems and that doesn't exist on 64-bit systems. */
#define R32(name)	{ STR(name), 4, 0, 0 }

/* Return a struct reg defining register NAME that's 64 bits on 64-bit
   systems and that doesn't exist on 32-bit systems. */
#define R64(name)	{ STR(name), 0, 8, 0 }

/* Return a struct reg placeholder for a register that doesn't exist. */
#define R0		{ 0, 0, 0, 0 }

/* UISA registers common across all architectures, including POWER.  */

#define COMMON_UISA_REGS \
  /*  0 */ R(r0), R(r1), R(r2), R(r3), R(r4), R(r5), R(r6), R(r7),  \
  /*  8 */ R(r8), R(r9), R(r10),R(r11),R(r12),R(r13),R(r14),R(r15), \
  /* 16 */ R(r16),R(r17),R(r18),R(r19),R(r20),R(r21),R(r22),R(r23), \
  /* 24 */ R(r24),R(r25),R(r26),R(r27),R(r28),R(r29),R(r30),R(r31), \
  /* 32 */ F(f0), F(f1), F(f2), F(f3), F(f4), F(f5), F(f6), F(f7),  \
  /* 40 */ F(f8), F(f9), F(f10),F(f11),F(f12),F(f13),F(f14),F(f15), \
  /* 48 */ F(f16),F(f17),F(f18),F(f19),F(f20),F(f21),F(f22),F(f23), \
  /* 56 */ F(f24),F(f25),F(f26),F(f27),F(f28),F(f29),F(f30),F(f31), \
  /* 64 */ R(pc), R(ps)

/* UISA-level SPRs for PowerPC.  */
#define PPC_UISA_SPRS \
  /* 66 */ R4(cr),  R(lr), R(ctr), R4(xer), R0

/* Segment registers, for PowerPC.  */
#define PPC_SEGMENT_REGS \
  /* 71 */ R32(sr0),  R32(sr1),  R32(sr2),  R32(sr3),  \
  /* 75 */ R32(sr4),  R32(sr5),  R32(sr6),  R32(sr7),  \
  /* 79 */ R32(sr8),  R32(sr9),  R32(sr10), R32(sr11), \
  /* 83 */ R32(sr12), R32(sr13), R32(sr14), R32(sr15)

/* OEA SPRs for PowerPC.  */
#define PPC_OEA_SPRS \
  /*  87 */ R4(pvr), \
  /*  88 */ R(ibat0u), R(ibat0l), R(ibat1u), R(ibat1l), \
  /*  92 */ R(ibat2u), R(ibat2l), R(ibat3u), R(ibat3l), \
  /*  96 */ R(dbat0u), R(dbat0l), R(dbat1u), R(dbat1l), \
  /* 100 */ R(dbat2u), R(dbat2l), R(dbat3u), R(dbat3l), \
  /* 104 */ R(sdr1),   R64(asr),  R(dar),    R4(dsisr), \
  /* 108 */ R(sprg0),  R(sprg1),  R(sprg2),  R(sprg3),  \
  /* 112 */ R(srr0),   R(srr1),   R(tbl),    R(tbu),    \
  /* 116 */ R4(dec),   R(dabr),   R4(ear)

/* IBM POWER (pre-PowerPC) architecture, user-level view.  We only cover
   user-level SPR's. */
static const struct reg registers_power[] =
{
  COMMON_UISA_REGS,
  /* 66 */ R4(cnd), R(lr), R(cnt), R4(xer), R4(mq)
};

/* PowerPC UISA - a PPC processor as viewed by user-level code.  A UISA-only
   view of the PowerPC. */
static const struct reg registers_powerpc[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS
};

/* IBM PowerPC 403. */
static const struct reg registers_403[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(icdbdr), R(esr),  R(dear), R(evpr),
  /* 123 */ R(cdbcr),  R(tsr),  R(tcr),  R(pit),
  /* 127 */ R(tbhi),   R(tblo), R(srr2), R(srr3),
  /* 131 */ R(dbsr),   R(dbcr), R(iac1), R(iac2),
  /* 135 */ R(dac1),   R(dac2), R(dccr), R(iccr),
  /* 139 */ R(pbl1),   R(pbu1), R(pbl2), R(pbu2)
};

/* IBM PowerPC 403GC. */
static const struct reg registers_403GC[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(icdbdr), R(esr),  R(dear), R(evpr),
  /* 123 */ R(cdbcr),  R(tsr),  R(tcr),  R(pit),
  /* 127 */ R(tbhi),   R(tblo), R(srr2), R(srr3),
  /* 131 */ R(dbsr),   R(dbcr), R(iac1), R(iac2),
  /* 135 */ R(dac1),   R(dac2), R(dccr), R(iccr),
  /* 139 */ R(pbl1),   R(pbu1), R(pbl2), R(pbu2),
  /* 143 */ R(zpr),    R(pid),  R(sgr),  R(dcwr),
  /* 147 */ R(tbhu),   R(tblu)
};

/* Motorola PowerPC 505. */
static const struct reg registers_505[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(eie), R(eid), R(nri)
};

/* Motorola PowerPC 860 or 850. */
static const struct reg registers_860[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(eie), R(eid), R(nri), R(cmpa),
  /* 123 */ R(cmpb), R(cmpc), R(cmpd), R(icr),
  /* 127 */ R(der), R(counta), R(countb), R(cmpe),
  /* 131 */ R(cmpf), R(cmpg), R(cmph), R(lctrl1),
  /* 135 */ R(lctrl2), R(ictrl), R(bar), R(ic_cst),
  /* 139 */ R(ic_adr), R(ic_dat), R(dc_cst), R(dc_adr),
  /* 143 */ R(dc_dat), R(dpdr), R(dpir), R(immr),
  /* 147 */ R(mi_ctr), R(mi_ap), R(mi_epn), R(mi_twc),
  /* 151 */ R(mi_rpn), R(md_ctr), R(m_casid), R(md_ap),
  /* 155 */ R(md_epn), R(md_twb), R(md_twc), R(md_rpn),
  /* 159 */ R(m_tw), R(mi_dbcam), R(mi_dbram0), R(mi_dbram1),
  /* 163 */ R(md_dbcam), R(md_dbram0), R(md_dbram1)
};

/* Motorola PowerPC 601.  Note that the 601 has different register numbers
   for reading and writing RTCU and RTCL.  However, how one reads and writes a
   register is the stub's problem.  */
static const struct reg registers_601[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(hid0), R(hid1), R(iabr), R(dabr),
  /* 123 */ R(pir), R(mq), R(rtcu), R(rtcl)
};

/* Motorola PowerPC 602. */
static const struct reg registers_602[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(hid0), R(hid1), R(iabr), R0,
  /* 123 */ R0, R(tcr), R(ibr), R(esassr),
  /* 127 */ R(sebr), R(ser), R(sp), R(lt)
};

/* Motorola/IBM PowerPC 603 or 603e. */
static const struct reg registers_603[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(hid0), R(hid1), R(iabr), R0,
  /* 123 */ R0, R(dmiss), R(dcmp), R(hash1),
  /* 127 */ R(hash2), R(imiss), R(icmp), R(rpa)
};

/* Motorola PowerPC 604 or 604e. */
static const struct reg registers_604[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(hid0), R(hid1), R(iabr), R(dabr),
  /* 123 */ R(pir), R(mmcr0), R(pmc1), R(pmc2),
  /* 127 */ R(sia), R(sda)
};

/* Motorola/IBM PowerPC 750 or 740. */
static const struct reg registers_750[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(hid0), R(hid1), R(iabr), R(dabr),
  /* 123 */ R0, R(ummcr0), R(upmc1), R(upmc2),
  /* 127 */ R(usia), R(ummcr1), R(upmc3), R(upmc4),
  /* 131 */ R(mmcr0), R(pmc1), R(pmc2), R(sia),
  /* 135 */ R(mmcr1), R(pmc3), R(pmc4), R(l2cr),
  /* 139 */ R(ictc), R(thrm1), R(thrm2), R(thrm3)
};


/* Information about a particular processor variant.  */

struct variant
  {
    /* Name of this variant.  */
    char *name;

    /* English description of the variant.  */
    char *description;

    /* bfd_arch_info.arch corresponding to variant. */
    enum bfd_architecture arch;

    /* bfd_arch_info.mach corresponding to variant. */
    unsigned long mach;

    /* Table of register names; registers[R] is the name of the register
       number R.  */
    int nregs;
    const struct reg *regs;
  };

#define num_registers(list) (sizeof (list) / sizeof((list)[0]))


/* Information in this table comes from the following web sites:
   IBM:       http://www.chips.ibm.com:80/products/embedded/
   Motorola:  http://www.mot.com/SPS/PowerPC/

   I'm sure I've got some of the variant descriptions not quite right.
   Please report any inaccuracies you find to GDB's maintainer.

   If you add entries to this table, please be sure to allow the new
   value as an argument to the --with-cpu flag, in configure.in.  */

static const struct variant variants[] =
{
  {"powerpc", "PowerPC user-level", bfd_arch_powerpc,
   bfd_mach_ppc, num_registers (registers_powerpc), registers_powerpc},
  {"power", "POWER user-level", bfd_arch_rs6000,
   bfd_mach_rs6k, num_registers (registers_power), registers_power},
  {"403", "IBM PowerPC 403", bfd_arch_powerpc,
   bfd_mach_ppc_403, num_registers (registers_403), registers_403},
  {"601", "Motorola PowerPC 601", bfd_arch_powerpc,
   bfd_mach_ppc_601, num_registers (registers_601), registers_601},
  {"602", "Motorola PowerPC 602", bfd_arch_powerpc,
   bfd_mach_ppc_602, num_registers (registers_602), registers_602},
  {"603", "Motorola/IBM PowerPC 603 or 603e", bfd_arch_powerpc,
   bfd_mach_ppc_603, num_registers (registers_603), registers_603},
  {"604", "Motorola PowerPC 604 or 604e", bfd_arch_powerpc,
   604, num_registers (registers_604), registers_604},
  {"403GC", "IBM PowerPC 403GC", bfd_arch_powerpc,
   bfd_mach_ppc_403gc, num_registers (registers_403GC), registers_403GC},
  {"505", "Motorola PowerPC 505", bfd_arch_powerpc,
   bfd_mach_ppc_505, num_registers (registers_505), registers_505},
  {"860", "Motorola PowerPC 860 or 850", bfd_arch_powerpc,
   bfd_mach_ppc_860, num_registers (registers_860), registers_860},
  {"750", "Motorola/IBM PowerPC 750 or 740", bfd_arch_powerpc,
   bfd_mach_ppc_750, num_registers (registers_750), registers_750},

  /* FIXME: I haven't checked the register sets of the following. */
  {"620", "Motorola PowerPC 620", bfd_arch_powerpc,
   bfd_mach_ppc_620, num_registers (registers_powerpc), registers_powerpc},
  {"a35", "PowerPC A35", bfd_arch_powerpc,
   bfd_mach_ppc_a35, num_registers (registers_powerpc), registers_powerpc},
  {"rs1", "IBM POWER RS1", bfd_arch_rs6000,
   bfd_mach_rs6k_rs1, num_registers (registers_power), registers_power},
  {"rsc", "IBM POWER RSC", bfd_arch_rs6000,
   bfd_mach_rs6k_rsc, num_registers (registers_power), registers_power},
  {"rs2", "IBM POWER RS2", bfd_arch_rs6000,
   bfd_mach_rs6k_rs2, num_registers (registers_power), registers_power},

  {0, 0, 0, 0}
};

#undef num_registers

/* Look up the variant named NAME in the `variants' table.  Return a
   pointer to the struct variant, or null if we couldn't find it.  */

static const struct variant *
find_variant_by_name (char *name)
{
  const struct variant *v;

  for (v = variants; v->name; v++)
    if (!strcmp (name, v->name))
      return v;

  return NULL;
}

/* Return the variant corresponding to architecture ARCH and machine number
   MACH.  If no such variant exists, return null. */

static const struct variant *
find_variant_by_arch (enum bfd_architecture arch, unsigned long mach)
{
  const struct variant *v;

  for (v = variants; v->name; v++)
    if (arch == v->arch && mach == v->mach)
      return v;

  return NULL;
}




static void
process_note_abi_tag_sections (bfd *abfd, asection *sect, void *obj)
{
  int *os_ident_ptr = obj;
  const char *name;
  unsigned int sectsize;

  name = bfd_get_section_name (abfd, sect);
  sectsize = bfd_section_size (abfd, sect);
  if (strcmp (name, ".note.ABI-tag") == 0 && sectsize > 0)
    {
      unsigned int name_length, data_length, note_type;
      char *note = alloca (sectsize);

      bfd_get_section_contents (abfd, sect, note,
                                (file_ptr) 0, (bfd_size_type) sectsize);

      name_length = bfd_h_get_32 (abfd, note);
      data_length = bfd_h_get_32 (abfd, note + 4);
      note_type   = bfd_h_get_32 (abfd, note + 8);

      if (name_length == 4 && data_length == 16 && note_type == 1
          && strcmp (note + 12, "GNU") == 0)
	{
	  int os_number = bfd_h_get_32 (abfd, note + 16);

	  /* The case numbers are from abi-tags in glibc */
	  switch (os_number)
	    {
	    case 0 :
	      *os_ident_ptr = ELFOSABI_LINUX;
	      break;
	    case 1 :
	      *os_ident_ptr = ELFOSABI_HURD;
	      break;
	    case 2 :
	      *os_ident_ptr = ELFOSABI_SOLARIS;
	      break;
	    default :
	      internal_error (__FILE__, __LINE__,
			      "process_note_abi_sections: unknown OS number %d",
			      os_number);
	      break;
	    }
	}
    }
}

/* Return one of the ELFOSABI_ constants for BFDs representing ELF
   executables.  If it's not an ELF executable or if the OS/ABI couldn't
   be determined, simply return -1. */

static int
get_elfosabi (bfd *abfd)
{
  int elfosabi = -1;

  if (abfd != NULL && bfd_get_flavour (abfd) == bfd_target_elf_flavour)
    {
      elfosabi = elf_elfheader (abfd)->e_ident[EI_OSABI];

      /* When elfosabi is 0 (ELFOSABI_NONE), this is supposed to indicate
         that we're on a SYSV system.  However, GNU/Linux uses a note section
	 to record OS/ABI info, but leaves e_ident[EI_OSABI] zero.  So we
	 have to check the note sections too. */
      if (elfosabi == 0)
	{
	  bfd_map_over_sections (abfd,
	                         process_note_abi_tag_sections,
				 &elfosabi);
	}
    }

  return elfosabi;
}



/* Initialize the current architecture based on INFO.  If possible, re-use an
   architecture from ARCHES, which is a list of architectures already created
   during this debugging session.

   Called e.g. at program startup, when reading a core file, and when reading
   a binary file. */

static struct gdbarch *
rs6000_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
{
  struct gdbarch *gdbarch;
  struct gdbarch_tdep *tdep;
  int wordsize, from_xcoff_exec, from_elf_exec, power, i, off;
  struct reg *regs;
  const struct variant *v;
  enum bfd_architecture arch;
  unsigned long mach;
  bfd abfd;
  int osabi, sysv_abi;

  from_xcoff_exec = info.abfd && info.abfd->format == bfd_object &&
    bfd_get_flavour (info.abfd) == bfd_target_xcoff_flavour;

  from_elf_exec = info.abfd && info.abfd->format == bfd_object &&
    bfd_get_flavour (info.abfd) == bfd_target_elf_flavour;

  sysv_abi = info.abfd && bfd_get_flavour (info.abfd) == bfd_target_elf_flavour;

  osabi = get_elfosabi (info.abfd);

  /* Check word size.  If INFO is from a binary file, infer it from that,
     else use the previously-inferred size. */
  if (from_xcoff_exec)
    {
      if (xcoff_data (info.abfd)->xcoff64)
	wordsize = 8;
      else
	wordsize = 4;
    }
  else if (from_elf_exec)
    {
      if (elf_elfheader (info.abfd)->e_ident[EI_CLASS] == ELFCLASS64)
	wordsize = 8;
      else
	wordsize = 4;
    }
  else
    {
      tdep = TDEP;
      if (tdep)
	wordsize = tdep->wordsize;
      else
	wordsize = 4;
    }

  /* Find a candidate among extant architectures. */
  for (arches = gdbarch_list_lookup_by_info (arches, &info);
       arches != NULL;
       arches = gdbarch_list_lookup_by_info (arches->next, &info))
    {
      /* Word size in the various PowerPC bfd_arch_info structs isn't
         meaningful, because 64-bit CPUs can run in 32-bit mode.  So, perform
         separate word size check. */
      tdep = gdbarch_tdep (arches->gdbarch);
      if (tdep && tdep->wordsize == wordsize && tdep->osabi == osabi)
	return arches->gdbarch;
    }

  /* None found, create a new architecture from INFO, whose bfd_arch_info
     validity depends on the source:
       - executable		useless
       - rs6000_host_arch()	good
       - core file		good
       - "set arch"		trust blindly
       - GDB startup		useless but harmless */

  if (!from_xcoff_exec)
    {
      arch = info.bfd_arch_info->arch;
      mach = info.bfd_arch_info->mach;
    }
  else
    {
      arch = bfd_arch_powerpc;
      mach = 0;
      bfd_default_set_arch_mach (&abfd, arch, mach);
      info.bfd_arch_info = bfd_get_arch_info (&abfd);
    }
  tdep = xmalloc (sizeof (struct gdbarch_tdep));
  tdep->wordsize = wordsize;
  tdep->osabi = osabi;
  gdbarch = gdbarch_alloc (&info, tdep);
  power = arch == bfd_arch_rs6000;

  /* Select instruction printer. */
  tm_print_insn = arch == power ? print_insn_rs6000 :
    info.byte_order == BIG_ENDIAN ? print_insn_big_powerpc :
      print_insn_little_powerpc;

  /* Choose variant. */
  v = find_variant_by_arch (arch, mach);
  if (!v)
    v = find_variant_by_name (power ? "power" : "powerpc");
  tdep->regs = v->regs;

  /* Calculate byte offsets in raw register array. */
  tdep->regoff = xmalloc (v->nregs * sizeof (int));
  for (i = off = 0; i < v->nregs; i++)
    {
      tdep->regoff[i] = off;
      off += regsize (v->regs + i, wordsize);
    }

  set_gdbarch_read_pc (gdbarch, generic_target_read_pc);
  set_gdbarch_write_pc (gdbarch, generic_target_write_pc);
  set_gdbarch_read_fp (gdbarch, generic_target_read_fp);
  set_gdbarch_write_fp (gdbarch, generic_target_write_fp);
  set_gdbarch_read_sp (gdbarch, generic_target_read_sp);
  set_gdbarch_write_sp (gdbarch, generic_target_write_sp);

  set_gdbarch_num_regs (gdbarch, v->nregs);
  set_gdbarch_sp_regnum (gdbarch, 1);
  set_gdbarch_fp_regnum (gdbarch, 1);
  set_gdbarch_pc_regnum (gdbarch, 64);
  set_gdbarch_register_name (gdbarch, rs6000_register_name);
  set_gdbarch_register_size (gdbarch, wordsize);
  set_gdbarch_register_bytes (gdbarch, off);
  set_gdbarch_register_byte (gdbarch, rs6000_register_byte);
  set_gdbarch_register_raw_size (gdbarch, rs6000_register_raw_size);
  set_gdbarch_max_register_raw_size (gdbarch, 8);
  set_gdbarch_register_virtual_size (gdbarch, rs6000_register_virtual_size);
  set_gdbarch_max_register_virtual_size (gdbarch, 8);
  set_gdbarch_register_virtual_type (gdbarch, rs6000_register_virtual_type);

  set_gdbarch_ptr_bit (gdbarch, wordsize * TARGET_CHAR_BIT);
  set_gdbarch_short_bit (gdbarch, 2 * TARGET_CHAR_BIT);
  set_gdbarch_int_bit (gdbarch, 4 * TARGET_CHAR_BIT);
  set_gdbarch_long_bit (gdbarch, wordsize * TARGET_CHAR_BIT);
  set_gdbarch_long_long_bit (gdbarch, 8 * TARGET_CHAR_BIT);
  set_gdbarch_float_bit (gdbarch, 4 * TARGET_CHAR_BIT);
  set_gdbarch_double_bit (gdbarch, 8 * TARGET_CHAR_BIT);
  set_gdbarch_long_double_bit (gdbarch, 8 * TARGET_CHAR_BIT);

  set_gdbarch_use_generic_dummy_frames (gdbarch, 1);
  set_gdbarch_call_dummy_length (gdbarch, 0);
  set_gdbarch_call_dummy_location (gdbarch, AT_ENTRY_POINT);
  set_gdbarch_call_dummy_address (gdbarch, entry_point_address);
  set_gdbarch_call_dummy_breakpoint_offset_p (gdbarch, 1);
  set_gdbarch_call_dummy_breakpoint_offset (gdbarch, 0);
  set_gdbarch_call_dummy_start_offset (gdbarch, 0);
  set_gdbarch_pc_in_call_dummy (gdbarch, generic_pc_in_call_dummy);
  set_gdbarch_call_dummy_p (gdbarch, 1);
  set_gdbarch_call_dummy_stack_adjust_p (gdbarch, 0);
  set_gdbarch_get_saved_register (gdbarch, generic_get_saved_register);
  set_gdbarch_fix_call_dummy (gdbarch, rs6000_fix_call_dummy);
  set_gdbarch_push_dummy_frame (gdbarch, generic_push_dummy_frame);
  set_gdbarch_save_dummy_frame_tos (gdbarch, generic_save_dummy_frame_tos);
  set_gdbarch_push_return_address (gdbarch, ppc_push_return_address);
  set_gdbarch_believe_pcc_promotion (gdbarch, 1);
  set_gdbarch_coerce_float_to_double (gdbarch, rs6000_coerce_float_to_double);

  set_gdbarch_register_convertible (gdbarch, rs6000_register_convertible);
  set_gdbarch_register_convert_to_virtual (gdbarch, rs6000_register_convert_to_virtual);
  set_gdbarch_register_convert_to_raw (gdbarch, rs6000_register_convert_to_raw);

  set_gdbarch_extract_return_value (gdbarch, rs6000_extract_return_value);
  
  if (sysv_abi)
    set_gdbarch_push_arguments (gdbarch, ppc_sysv_abi_push_arguments);
  else
    set_gdbarch_push_arguments (gdbarch, rs6000_push_arguments);

  set_gdbarch_store_struct_return (gdbarch, rs6000_store_struct_return);
  set_gdbarch_store_return_value (gdbarch, rs6000_store_return_value);
  set_gdbarch_extract_struct_value_address (gdbarch, rs6000_extract_struct_value_address);
  set_gdbarch_use_struct_convention (gdbarch, generic_use_struct_convention);

  set_gdbarch_pop_frame (gdbarch, rs6000_pop_frame);

  set_gdbarch_skip_prologue (gdbarch, rs6000_skip_prologue);
  set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
  set_gdbarch_decr_pc_after_break (gdbarch, 0);
  set_gdbarch_function_start_offset (gdbarch, 0);
  set_gdbarch_breakpoint_from_pc (gdbarch, rs6000_breakpoint_from_pc);

  /* Not sure on this. FIXMEmgo */
  set_gdbarch_frame_args_skip (gdbarch, 8);

  set_gdbarch_frame_chain_valid (gdbarch, file_frame_chain_valid);
  if (osabi == ELFOSABI_LINUX)
    {
      set_gdbarch_frameless_function_invocation (gdbarch,
	ppc_linux_frameless_function_invocation);
      set_gdbarch_frame_chain (gdbarch, ppc_linux_frame_chain);
      set_gdbarch_frame_saved_pc (gdbarch, ppc_linux_frame_saved_pc);

      set_gdbarch_frame_init_saved_regs (gdbarch,
	                                 ppc_linux_frame_init_saved_regs);
      set_gdbarch_init_extra_frame_info (gdbarch,
	                                 ppc_linux_init_extra_frame_info);

      set_gdbarch_memory_remove_breakpoint (gdbarch,
	                                    ppc_linux_memory_remove_breakpoint);
    }
  else
    {
      set_gdbarch_frameless_function_invocation (gdbarch,
	rs6000_frameless_function_invocation);
      set_gdbarch_frame_chain (gdbarch, rs6000_frame_chain);
      set_gdbarch_frame_saved_pc (gdbarch, rs6000_frame_saved_pc);

      set_gdbarch_frame_init_saved_regs (gdbarch, rs6000_frame_init_saved_regs);
      set_gdbarch_init_extra_frame_info (gdbarch, rs6000_init_extra_frame_info);

      /* Handle RS/6000 function pointers.  */
      set_gdbarch_convert_from_func_ptr_addr (gdbarch,
	rs6000_convert_from_func_ptr_addr);
    }
  set_gdbarch_frame_args_address (gdbarch, rs6000_frame_args_address);
  set_gdbarch_frame_locals_address (gdbarch, rs6000_frame_args_address);
  set_gdbarch_saved_pc_after_call (gdbarch, rs6000_saved_pc_after_call);

  /* We can't tell how many args there are
     now that the C compiler delays popping them.  */
  set_gdbarch_frame_num_args (gdbarch, frame_num_args_unknown);

  return gdbarch;
}

/* Initialization code.  */

void
_initialize_rs6000_tdep (void)
{
  register_gdbarch_init (bfd_arch_rs6000, rs6000_gdbarch_init);
  register_gdbarch_init (bfd_arch_powerpc, rs6000_gdbarch_init);
}