summaryrefslogtreecommitdiff
path: root/gcc/double-int.c
blob: 2d692f94b6a522d17a3290d5ce70dfdbbcf455b7 (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
/* Operations with long integers.
   Copyright (C) 2006-2016 Free Software Foundation, Inc.

This file is part of GCC.

GCC 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, or (at your option) any
later version.

GCC 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 GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"			/* For BITS_PER_UNIT and *_BIG_ENDIAN.  */
#include "tree.h"

static int add_double_with_sign (unsigned HOST_WIDE_INT, HOST_WIDE_INT,
				 unsigned HOST_WIDE_INT, HOST_WIDE_INT,
				 unsigned HOST_WIDE_INT *, HOST_WIDE_INT *,
				 bool);

#define add_double(l1,h1,l2,h2,lv,hv) \
  add_double_with_sign (l1, h1, l2, h2, lv, hv, false)

static int neg_double (unsigned HOST_WIDE_INT, HOST_WIDE_INT,
		       unsigned HOST_WIDE_INT *, HOST_WIDE_INT *);

static int mul_double_wide_with_sign (unsigned HOST_WIDE_INT, HOST_WIDE_INT,
				      unsigned HOST_WIDE_INT, HOST_WIDE_INT,
				      unsigned HOST_WIDE_INT *, HOST_WIDE_INT *,
				      unsigned HOST_WIDE_INT *, HOST_WIDE_INT *,
				      bool);

#define mul_double(l1,h1,l2,h2,lv,hv) \
  mul_double_wide_with_sign (l1, h1, l2, h2, lv, hv, NULL, NULL, false)

static int div_and_round_double (unsigned, int, unsigned HOST_WIDE_INT,
				 HOST_WIDE_INT, unsigned HOST_WIDE_INT,
				 HOST_WIDE_INT, unsigned HOST_WIDE_INT *,
				 HOST_WIDE_INT *, unsigned HOST_WIDE_INT *,
				 HOST_WIDE_INT *);

/* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
   overflow.  Suppose A, B and SUM have the same respective signs as A1, B1,
   and SUM1.  Then this yields nonzero if overflow occurred during the
   addition.

   Overflow occurs if A and B have the same sign, but A and SUM differ in
   sign.  Use `^' to test whether signs differ, and `< 0' to isolate the
   sign.  */
#define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)

/* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
   We do that by representing the two-word integer in 4 words, with only
   HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
   number.  The value of the word is LOWPART + HIGHPART * BASE.  */

#define LOWPART(x) \
  ((x) & ((HOST_WIDE_INT_1U << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
#define HIGHPART(x) \
  ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
#define BASE (HOST_WIDE_INT_1U << HOST_BITS_PER_WIDE_INT / 2)

/* Unpack a two-word integer into 4 words.
   LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
   WORDS points to the array of HOST_WIDE_INTs.  */

static void
encode (HOST_WIDE_INT *words, unsigned HOST_WIDE_INT low, HOST_WIDE_INT hi)
{
  words[0] = LOWPART (low);
  words[1] = HIGHPART (low);
  words[2] = LOWPART (hi);
  words[3] = HIGHPART (hi);
}

/* Pack an array of 4 words into a two-word integer.
   WORDS points to the array of words.
   The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces.  */

static void
decode (HOST_WIDE_INT *words, unsigned HOST_WIDE_INT *low,
	HOST_WIDE_INT *hi)
{
  *low = words[0] + words[1] * BASE;
  *hi = words[2] + words[3] * BASE;
}

/* Add two doubleword integers with doubleword result.
   Return nonzero if the operation overflows according to UNSIGNED_P.
   Each argument is given as two `HOST_WIDE_INT' pieces.
   One argument is L1 and H1; the other, L2 and H2.
   The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV.  */

static int
add_double_with_sign (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
		      unsigned HOST_WIDE_INT l2, HOST_WIDE_INT h2,
		      unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv,
		      bool unsigned_p)
{
  unsigned HOST_WIDE_INT l;
  HOST_WIDE_INT h;

  l = l1 + l2;
  h = (HOST_WIDE_INT) ((unsigned HOST_WIDE_INT) h1
		       + (unsigned HOST_WIDE_INT) h2
		       + (l < l1));

  *lv = l;
  *hv = h;

  if (unsigned_p)
    return ((unsigned HOST_WIDE_INT) h < (unsigned HOST_WIDE_INT) h1
	    || (h == h1
		&& l < l1));
  else
    return OVERFLOW_SUM_SIGN (h1, h2, h);
}

/* Negate a doubleword integer with doubleword result.
   Return nonzero if the operation overflows, assuming it's signed.
   The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
   The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV.  */

static int
neg_double (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
	    unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv)
{
  if (l1 == 0)
    {
      *lv = 0;
      *hv = - (unsigned HOST_WIDE_INT) h1;
      return (*hv & h1) < 0;
    }
  else
    {
      *lv = -l1;
      *hv = ~h1;
      return 0;
    }
}

/* Multiply two doubleword integers with quadword result.
   Return nonzero if the operation overflows according to UNSIGNED_P.
   Each argument is given as two `HOST_WIDE_INT' pieces.
   One argument is L1 and H1; the other, L2 and H2.
   The value is stored as four `HOST_WIDE_INT' pieces in *LV and *HV,
   *LW and *HW.
   If lw is NULL then only the low part and no overflow is computed.  */

static int
mul_double_wide_with_sign (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
			   unsigned HOST_WIDE_INT l2, HOST_WIDE_INT h2,
			   unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv,
			   unsigned HOST_WIDE_INT *lw, HOST_WIDE_INT *hw,
			   bool unsigned_p)
{
  HOST_WIDE_INT arg1[4];
  HOST_WIDE_INT arg2[4];
  HOST_WIDE_INT prod[4 * 2];
  unsigned HOST_WIDE_INT carry;
  int i, j, k;
  unsigned HOST_WIDE_INT neglow;
  HOST_WIDE_INT neghigh;

  encode (arg1, l1, h1);
  encode (arg2, l2, h2);

  memset (prod, 0, sizeof prod);

  for (i = 0; i < 4; i++)
    {
      carry = 0;
      for (j = 0; j < 4; j++)
	{
	  k = i + j;
	  /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000.  */
	  carry += (unsigned HOST_WIDE_INT) arg1[i] * arg2[j];
	  /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF.  */
	  carry += prod[k];
	  prod[k] = LOWPART (carry);
	  carry = HIGHPART (carry);
	}
      prod[i + 4] = carry;
    }

  decode (prod, lv, hv);

  /* We are not interested in the wide part nor in overflow.  */
  if (lw == NULL)
    return 0;

  decode (prod + 4, lw, hw);

  /* Unsigned overflow is immediate.  */
  if (unsigned_p)
    return (*lw | *hw) != 0;

  /* Check for signed overflow by calculating the signed representation of the
     top half of the result; it should agree with the low half's sign bit.  */
  if (h1 < 0)
    {
      neg_double (l2, h2, &neglow, &neghigh);
      add_double (neglow, neghigh, *lw, *hw, lw, hw);
    }
  if (h2 < 0)
    {
      neg_double (l1, h1, &neglow, &neghigh);
      add_double (neglow, neghigh, *lw, *hw, lw, hw);
    }
  return (*hv < 0 ? ~(*lw & *hw) : *lw | *hw) != 0;
}

/* Shift the doubleword integer in L1, H1 right by COUNT places
   keeping only PREC bits of result.  ARITH nonzero specifies
   arithmetic shifting; otherwise use logical shift.
   Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV.  */

static void
rshift_double (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
	       unsigned HOST_WIDE_INT count, unsigned int prec,
	       unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv,
	       bool arith)
{
  unsigned HOST_WIDE_INT signmask;

  signmask = (arith
	      ? -((unsigned HOST_WIDE_INT) h1 >> (HOST_BITS_PER_WIDE_INT - 1))
	      : 0);

  if (count >= HOST_BITS_PER_DOUBLE_INT)
    {
      /* Shifting by the host word size is undefined according to the
	 ANSI standard, so we must handle this as a special case.  */
      *hv = 0;
      *lv = 0;
    }
  else if (count >= HOST_BITS_PER_WIDE_INT)
    {
      *hv = 0;
      *lv = (unsigned HOST_WIDE_INT) h1 >> (count - HOST_BITS_PER_WIDE_INT);
    }
  else
    {
      *hv = (unsigned HOST_WIDE_INT) h1 >> count;
      *lv = ((l1 >> count)
	     | ((unsigned HOST_WIDE_INT) h1
		<< (HOST_BITS_PER_WIDE_INT - count - 1) << 1));
    }

  /* Zero / sign extend all bits that are beyond the precision.  */

  if (count >= prec)
    {
      *hv = signmask;
      *lv = signmask;
    }
  else if ((prec - count) >= HOST_BITS_PER_DOUBLE_INT)
    ;
  else if ((prec - count) >= HOST_BITS_PER_WIDE_INT)
    {
      *hv &= ~(HOST_WIDE_INT_M1U << (prec - count - HOST_BITS_PER_WIDE_INT));
      *hv |= signmask << (prec - count - HOST_BITS_PER_WIDE_INT);
    }
  else
    {
      *hv = signmask;
      *lv &= ~(HOST_WIDE_INT_M1U << (prec - count));
      *lv |= signmask << (prec - count);
    }
}

/* Shift the doubleword integer in L1, H1 left by COUNT places
   keeping only PREC bits of result.
   Shift right if COUNT is negative.
   ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
   Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV.  */

static void
lshift_double (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
	       unsigned HOST_WIDE_INT count, unsigned int prec,
	       unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv)
{
  unsigned HOST_WIDE_INT signmask;

  if (count >= HOST_BITS_PER_DOUBLE_INT)
    {
      /* Shifting by the host word size is undefined according to the
	 ANSI standard, so we must handle this as a special case.  */
      *hv = 0;
      *lv = 0;
    }
  else if (count >= HOST_BITS_PER_WIDE_INT)
    {
      *hv = l1 << (count - HOST_BITS_PER_WIDE_INT);
      *lv = 0;
    }
  else
    {
      *hv = (((unsigned HOST_WIDE_INT) h1 << count)
	     | (l1 >> (HOST_BITS_PER_WIDE_INT - count - 1) >> 1));
      *lv = l1 << count;
    }

  /* Sign extend all bits that are beyond the precision.  */

  signmask = -((prec > HOST_BITS_PER_WIDE_INT
		? ((unsigned HOST_WIDE_INT) *hv
		   >> (prec - HOST_BITS_PER_WIDE_INT - 1))
		: (*lv >> (prec - 1))) & 1);

  if (prec >= HOST_BITS_PER_DOUBLE_INT)
    ;
  else if (prec >= HOST_BITS_PER_WIDE_INT)
    {
      *hv &= ~(HOST_WIDE_INT_M1U << (prec - HOST_BITS_PER_WIDE_INT));
      *hv |= signmask << (prec - HOST_BITS_PER_WIDE_INT);
    }
  else
    {
      *hv = signmask;
      *lv &= ~(HOST_WIDE_INT_M1U << prec);
      *lv |= signmask << prec;
    }
}

/* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
   for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
   CODE is a tree code for a kind of division, one of
   TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
   or EXACT_DIV_EXPR
   It controls how the quotient is rounded to an integer.
   Return nonzero if the operation overflows.
   UNS nonzero says do unsigned division.  */

static int
div_and_round_double (unsigned code, int uns,
		      /* num == numerator == dividend */
		      unsigned HOST_WIDE_INT lnum_orig,
		      HOST_WIDE_INT hnum_orig,
		      /* den == denominator == divisor */
		      unsigned HOST_WIDE_INT lden_orig,
		      HOST_WIDE_INT hden_orig,
		      unsigned HOST_WIDE_INT *lquo,
		      HOST_WIDE_INT *hquo, unsigned HOST_WIDE_INT *lrem,
		      HOST_WIDE_INT *hrem)
{
  int quo_neg = 0;
  HOST_WIDE_INT num[4 + 1];	/* extra element for scaling.  */
  HOST_WIDE_INT den[4], quo[4];
  int i, j;
  unsigned HOST_WIDE_INT work;
  unsigned HOST_WIDE_INT carry = 0;
  unsigned HOST_WIDE_INT lnum = lnum_orig;
  HOST_WIDE_INT hnum = hnum_orig;
  unsigned HOST_WIDE_INT lden = lden_orig;
  HOST_WIDE_INT hden = hden_orig;
  int overflow = 0;

  if (hden == 0 && lden == 0)
    overflow = 1, lden = 1;

  /* Calculate quotient sign and convert operands to unsigned.  */
  if (!uns)
    {
      if (hnum < 0)
	{
	  quo_neg = ~ quo_neg;
	  /* (minimum integer) / (-1) is the only overflow case.  */
	  if (neg_double (lnum, hnum, &lnum, &hnum)
	      && ((HOST_WIDE_INT) lden & hden) == -1)
	    overflow = 1;
	}
      if (hden < 0)
	{
	  quo_neg = ~ quo_neg;
	  neg_double (lden, hden, &lden, &hden);
	}
    }

  if (hnum == 0 && hden == 0)
    {				/* single precision */
      *hquo = *hrem = 0;
      /* This unsigned division rounds toward zero.  */
      *lquo = lnum / lden;
      goto finish_up;
    }

  if (hnum == 0)
    {				/* trivial case: dividend < divisor */
      /* hden != 0 already checked.  */
      *hquo = *lquo = 0;
      *hrem = hnum;
      *lrem = lnum;
      goto finish_up;
    }

  memset (quo, 0, sizeof quo);

  memset (num, 0, sizeof num);	/* to zero 9th element */
  memset (den, 0, sizeof den);

  encode (num, lnum, hnum);
  encode (den, lden, hden);

  /* Special code for when the divisor < BASE.  */
  if (hden == 0 && lden < (unsigned HOST_WIDE_INT) BASE)
    {
      /* hnum != 0 already checked.  */
      for (i = 4 - 1; i >= 0; i--)
	{
	  work = num[i] + carry * BASE;
	  quo[i] = work / lden;
	  carry = work % lden;
	}
    }
  else
    {
      /* Full double precision division,
	 with thanks to Don Knuth's "Seminumerical Algorithms".  */
      int num_hi_sig, den_hi_sig;
      unsigned HOST_WIDE_INT quo_est, scale;

      /* Find the highest nonzero divisor digit.  */
      for (i = 4 - 1;; i--)
	if (den[i] != 0)
	  {
	    den_hi_sig = i;
	    break;
	  }

      /* Insure that the first digit of the divisor is at least BASE/2.
	 This is required by the quotient digit estimation algorithm.  */

      scale = BASE / (den[den_hi_sig] + 1);
      if (scale > 1)
	{		/* scale divisor and dividend */
	  carry = 0;
	  for (i = 0; i <= 4 - 1; i++)
	    {
	      work = (num[i] * scale) + carry;
	      num[i] = LOWPART (work);
	      carry = HIGHPART (work);
	    }

	  num[4] = carry;
	  carry = 0;
	  for (i = 0; i <= 4 - 1; i++)
	    {
	      work = (den[i] * scale) + carry;
	      den[i] = LOWPART (work);
	      carry = HIGHPART (work);
	      if (den[i] != 0) den_hi_sig = i;
	    }
	}

      num_hi_sig = 4;

      /* Main loop */
      for (i = num_hi_sig - den_hi_sig - 1; i >= 0; i--)
	{
	  /* Guess the next quotient digit, quo_est, by dividing the first
	     two remaining dividend digits by the high order quotient digit.
	     quo_est is never low and is at most 2 high.  */
	  unsigned HOST_WIDE_INT tmp;

	  num_hi_sig = i + den_hi_sig + 1;
	  work = num[num_hi_sig] * BASE + num[num_hi_sig - 1];
	  if (num[num_hi_sig] != den[den_hi_sig])
	    quo_est = work / den[den_hi_sig];
	  else
	    quo_est = BASE - 1;

	  /* Refine quo_est so it's usually correct, and at most one high.  */
	  tmp = work - quo_est * den[den_hi_sig];
	  if (tmp < BASE
	      && (den[den_hi_sig - 1] * quo_est
		  > (tmp * BASE + num[num_hi_sig - 2])))
	    quo_est--;

	  /* Try QUO_EST as the quotient digit, by multiplying the
	     divisor by QUO_EST and subtracting from the remaining dividend.
	     Keep in mind that QUO_EST is the I - 1st digit.  */

	  carry = 0;
	  for (j = 0; j <= den_hi_sig; j++)
	    {
	      work = quo_est * den[j] + carry;
	      carry = HIGHPART (work);
	      work = num[i + j] - LOWPART (work);
	      num[i + j] = LOWPART (work);
	      carry += HIGHPART (work) != 0;
	    }

	  /* If quo_est was high by one, then num[i] went negative and
	     we need to correct things.  */
	  if (num[num_hi_sig] < (HOST_WIDE_INT) carry)
	    {
	      quo_est--;
	      carry = 0;		/* add divisor back in */
	      for (j = 0; j <= den_hi_sig; j++)
		{
		  work = num[i + j] + den[j] + carry;
		  carry = HIGHPART (work);
		  num[i + j] = LOWPART (work);
		}

	      num [num_hi_sig] += carry;
	    }

	  /* Store the quotient digit.  */
	  quo[i] = quo_est;
	}
    }

  decode (quo, lquo, hquo);

 finish_up:
  /* If result is negative, make it so.  */
  if (quo_neg)
    neg_double (*lquo, *hquo, lquo, hquo);

  /* Compute trial remainder:  rem = num - (quo * den)  */
  mul_double (*lquo, *hquo, lden_orig, hden_orig, lrem, hrem);
  neg_double (*lrem, *hrem, lrem, hrem);
  add_double (lnum_orig, hnum_orig, *lrem, *hrem, lrem, hrem);

  switch (code)
    {
    case TRUNC_DIV_EXPR:
    case TRUNC_MOD_EXPR:	/* round toward zero */
    case EXACT_DIV_EXPR:	/* for this one, it shouldn't matter */
      return overflow;

    case FLOOR_DIV_EXPR:
    case FLOOR_MOD_EXPR:	/* round toward negative infinity */
      if (quo_neg && (*lrem != 0 || *hrem != 0))   /* ratio < 0 && rem != 0 */
	{
	  /* quo = quo - 1;  */
	  add_double (*lquo, *hquo, HOST_WIDE_INT_M1, HOST_WIDE_INT_M1,
		      lquo, hquo);
	}
      else
	return overflow;
      break;

    case CEIL_DIV_EXPR:
    case CEIL_MOD_EXPR:		/* round toward positive infinity */
      if (!quo_neg && (*lrem != 0 || *hrem != 0))  /* ratio > 0 && rem != 0 */
	{
	  add_double (*lquo, *hquo, HOST_WIDE_INT_1, HOST_WIDE_INT_0,
		      lquo, hquo);
	}
      else
	return overflow;
      break;

    case ROUND_DIV_EXPR:
    case ROUND_MOD_EXPR:	/* round to closest integer */
      {
	unsigned HOST_WIDE_INT labs_rem = *lrem;
	HOST_WIDE_INT habs_rem = *hrem;
	unsigned HOST_WIDE_INT labs_den = lden, lnegabs_rem, ldiff;
	HOST_WIDE_INT habs_den = hden, hnegabs_rem, hdiff;

	/* Get absolute values.  */
	if (!uns && *hrem < 0)
	  neg_double (*lrem, *hrem, &labs_rem, &habs_rem);
	if (!uns && hden < 0)
	  neg_double (lden, hden, &labs_den, &habs_den);

	/* If abs(rem) >= abs(den) - abs(rem), adjust the quotient.  */
	neg_double (labs_rem, habs_rem, &lnegabs_rem, &hnegabs_rem);
	add_double (labs_den, habs_den, lnegabs_rem, hnegabs_rem,
		    &ldiff, &hdiff);

	if (((unsigned HOST_WIDE_INT) habs_rem
	     > (unsigned HOST_WIDE_INT) hdiff)
	    || (habs_rem == hdiff && labs_rem >= ldiff))
	  {
	    if (quo_neg)
	      /* quo = quo - 1;  */
	      add_double (*lquo, *hquo,
			  HOST_WIDE_INT_M1, HOST_WIDE_INT_M1, lquo, hquo);
	    else
	      /* quo = quo + 1; */
	      add_double (*lquo, *hquo, HOST_WIDE_INT_1, HOST_WIDE_INT_0,
			  lquo, hquo);
	  }
	else
	  return overflow;
      }
      break;

    default:
      gcc_unreachable ();
    }

  /* Compute true remainder:  rem = num - (quo * den)  */
  mul_double (*lquo, *hquo, lden_orig, hden_orig, lrem, hrem);
  neg_double (*lrem, *hrem, lrem, hrem);
  add_double (lnum_orig, hnum_orig, *lrem, *hrem, lrem, hrem);
  return overflow;
}


/* Construct from a buffer of length LEN.  BUFFER will be read according
   to byte endianess and word endianess.  Only the lower LEN bytes
   of the result are set; the remaining high bytes are cleared.  */

double_int
double_int::from_buffer (const unsigned char *buffer, int len)
{
  double_int result = double_int_zero;
  int words = len / UNITS_PER_WORD;

  gcc_assert (len * BITS_PER_UNIT <= HOST_BITS_PER_DOUBLE_INT);

  for (int byte = 0; byte < len; byte++)
    {
      int offset;
      int bitpos = byte * BITS_PER_UNIT;
      unsigned HOST_WIDE_INT value;

      if (len > UNITS_PER_WORD)
	{
	  int word = byte / UNITS_PER_WORD;

	  if (WORDS_BIG_ENDIAN)
	    word = (words - 1) - word;

	  offset = word * UNITS_PER_WORD;

	  if (BYTES_BIG_ENDIAN)
	    offset += (UNITS_PER_WORD - 1) - (byte % UNITS_PER_WORD);
	  else
	    offset += byte % UNITS_PER_WORD;
	}
      else
	offset = BYTES_BIG_ENDIAN ? (len - 1) - byte : byte;

      value = (unsigned HOST_WIDE_INT) buffer[offset];

      if (bitpos < HOST_BITS_PER_WIDE_INT)
	result.low |= value << bitpos;
      else
	result.high |= value << (bitpos - HOST_BITS_PER_WIDE_INT);
    }

  return result;
}


/* Returns mask for PREC bits.  */

double_int
double_int::mask (unsigned prec)
{
  unsigned HOST_WIDE_INT m;
  double_int mask;

  if (prec > HOST_BITS_PER_WIDE_INT)
    {
      prec -= HOST_BITS_PER_WIDE_INT;
      m = ((unsigned HOST_WIDE_INT) 2 << (prec - 1)) - 1;
      mask.high = (HOST_WIDE_INT) m;
      mask.low = ALL_ONES;
    }
  else
    {
      mask.high = 0;
      mask.low = prec ? ((unsigned HOST_WIDE_INT) 2 << (prec - 1)) - 1 : 0;
    }

  return mask;
}

/* Returns a maximum value for signed or unsigned integer
   of precision PREC.  */

double_int
double_int::max_value (unsigned int prec, bool uns)
{
  return double_int::mask (prec - (uns ? 0 : 1));
}

/* Returns a minimum value for signed or unsigned integer
   of precision PREC.  */

double_int
double_int::min_value (unsigned int prec, bool uns)
{
  if (uns)
    return double_int_zero;
  return double_int_one.lshift (prec - 1, prec, false);
}

/* Clears the bits of CST over the precision PREC.  If UNS is false, the bits
   outside of the precision are set to the sign bit (i.e., the PREC-th one),
   otherwise they are set to zero.

   This corresponds to returning the value represented by PREC lowermost bits
   of CST, with the given signedness.  */

double_int
double_int::ext (unsigned prec, bool uns) const
{
  if (uns)
    return this->zext (prec);
  else
    return this->sext (prec);
}

/* The same as double_int::ext with UNS = true.  */

double_int
double_int::zext (unsigned prec) const
{
  const double_int &cst = *this;
  double_int mask = double_int::mask (prec);
  double_int r;

  r.low = cst.low & mask.low;
  r.high = cst.high & mask.high;

  return r;
}

/* The same as double_int::ext with UNS = false.  */

double_int
double_int::sext (unsigned prec) const
{
  const double_int &cst = *this;
  double_int mask = double_int::mask (prec);
  double_int r;
  unsigned HOST_WIDE_INT snum;

  if (prec <= HOST_BITS_PER_WIDE_INT)
    snum = cst.low;
  else
    {
      prec -= HOST_BITS_PER_WIDE_INT;
      snum = (unsigned HOST_WIDE_INT) cst.high;
    }
  if (((snum >> (prec - 1)) & 1) == 1)
    {
      r.low = cst.low | ~mask.low;
      r.high = cst.high | ~mask.high;
    }
  else
    {
      r.low = cst.low & mask.low;
      r.high = cst.high & mask.high;
    }

  return r;
}

/* Returns true if CST fits in signed HOST_WIDE_INT.  */

bool
double_int::fits_shwi () const
{
  const double_int &cst = *this;
  if (cst.high == 0)
    return (HOST_WIDE_INT) cst.low >= 0;
  else if (cst.high == -1)
    return (HOST_WIDE_INT) cst.low < 0;
  else
    return false;
}

/* Returns true if CST fits in HOST_WIDE_INT if UNS is false, or in
   unsigned HOST_WIDE_INT if UNS is true.  */

bool
double_int::fits_hwi (bool uns) const
{
  if (uns)
    return this->fits_uhwi ();
  else
    return this->fits_shwi ();
}

/* Returns A * B.  */

double_int
double_int::operator * (double_int b) const
{
  const double_int &a = *this;
  double_int ret;
  mul_double (a.low, a.high, b.low, b.high, &ret.low, &ret.high);
  return ret;
}

/* Multiplies *this with B and returns a reference to *this.  */

double_int &
double_int::operator *= (double_int b)
{
  mul_double (low, high, b.low, b.high, &low, &high);
  return *this;
}

/* Returns A * B. If the operation overflows according to UNSIGNED_P,
   *OVERFLOW is set to nonzero.  */

double_int
double_int::mul_with_sign (double_int b, bool unsigned_p, bool *overflow) const
{
  const double_int &a = *this;
  double_int ret, tem;
  *overflow = mul_double_wide_with_sign (a.low, a.high, b.low, b.high,
					 &ret.low, &ret.high,
					 &tem.low, &tem.high, unsigned_p);
  return ret;
}

double_int
double_int::wide_mul_with_sign (double_int b, bool unsigned_p,
				double_int *higher, bool *overflow) const

{
  double_int lower;
  *overflow = mul_double_wide_with_sign (low, high, b.low, b.high,
					 &lower.low, &lower.high,
					 &higher->low, &higher->high,
					 unsigned_p);
  return lower;
}

/* Returns A + B.  */

double_int
double_int::operator + (double_int b) const
{
  const double_int &a = *this;
  double_int ret;
  add_double (a.low, a.high, b.low, b.high, &ret.low, &ret.high);
  return ret;
}

/* Adds B to *this and returns a reference to *this.  */

double_int &
double_int::operator += (double_int b)
{
  add_double (low, high, b.low, b.high, &low, &high);
  return *this;
}


/* Returns A + B. If the operation overflows according to UNSIGNED_P,
   *OVERFLOW is set to nonzero.  */

double_int
double_int::add_with_sign (double_int b, bool unsigned_p, bool *overflow) const
{
  const double_int &a = *this;
  double_int ret;
  *overflow = add_double_with_sign (a.low, a.high, b.low, b.high,
                                    &ret.low, &ret.high, unsigned_p);
  return ret;
}

/* Returns A - B.  */

double_int
double_int::operator - (double_int b) const
{
  const double_int &a = *this;
  double_int ret;
  neg_double (b.low, b.high, &b.low, &b.high);
  add_double (a.low, a.high, b.low, b.high, &ret.low, &ret.high);
  return ret;
}

/* Subtracts B from *this and returns a reference to *this.  */

double_int &
double_int::operator -= (double_int b)
{
  neg_double (b.low, b.high, &b.low, &b.high);
  add_double (low, high, b.low, b.high, &low, &high);
  return *this;
}


/* Returns A - B. If the operation overflows via inconsistent sign bits,
   *OVERFLOW is set to nonzero.  */

double_int
double_int::sub_with_overflow (double_int b, bool *overflow) const
{
  double_int ret;
  neg_double (b.low, b.high, &ret.low, &ret.high);
  add_double (low, high, ret.low, ret.high, &ret.low, &ret.high);
  *overflow = OVERFLOW_SUM_SIGN (ret.high, b.high, high);
  return ret;
}

/* Returns -A.  */

double_int
double_int::operator - () const
{
  const double_int &a = *this;
  double_int ret;
  neg_double (a.low, a.high, &ret.low, &ret.high);
  return ret;
}

double_int
double_int::neg_with_overflow (bool *overflow) const
{
  double_int ret;
  *overflow = neg_double (low, high, &ret.low, &ret.high);
  return ret;
}

/* Returns A / B (computed as unsigned depending on UNS, and rounded as
   specified by CODE).  CODE is enum tree_code in fact, but double_int.h
   must be included before tree.h.  The remainder after the division is
   stored to MOD.  */

double_int
double_int::divmod_with_overflow (double_int b, bool uns, unsigned code,
				  double_int *mod, bool *overflow) const
{
  const double_int &a = *this;
  double_int ret;

  *overflow = div_and_round_double (code, uns, a.low, a.high,
				    b.low, b.high, &ret.low, &ret.high,
				    &mod->low, &mod->high);
  return ret;
}

double_int
double_int::divmod (double_int b, bool uns, unsigned code,
		    double_int *mod) const
{
  const double_int &a = *this;
  double_int ret;

  div_and_round_double (code, uns, a.low, a.high,
			b.low, b.high, &ret.low, &ret.high,
			&mod->low, &mod->high);
  return ret;
}

/* The same as double_int::divmod with UNS = false.  */

double_int
double_int::sdivmod (double_int b, unsigned code, double_int *mod) const
{
  return this->divmod (b, false, code, mod);
}

/* The same as double_int::divmod with UNS = true.  */

double_int
double_int::udivmod (double_int b, unsigned code, double_int *mod) const
{
  return this->divmod (b, true, code, mod);
}

/* Returns A / B (computed as unsigned depending on UNS, and rounded as
   specified by CODE).  CODE is enum tree_code in fact, but double_int.h
   must be included before tree.h.  */

double_int
double_int::div (double_int b, bool uns, unsigned code) const
{
  double_int mod;

  return this->divmod (b, uns, code, &mod);
}

/* The same as double_int::div with UNS = false.  */

double_int
double_int::sdiv (double_int b, unsigned code) const
{
  return this->div (b, false, code);
}

/* The same as double_int::div with UNS = true.  */

double_int
double_int::udiv (double_int b, unsigned code) const
{
  return this->div (b, true, code);
}

/* Returns A % B (computed as unsigned depending on UNS, and rounded as
   specified by CODE).  CODE is enum tree_code in fact, but double_int.h
   must be included before tree.h.  */

double_int
double_int::mod (double_int b, bool uns, unsigned code) const
{
  double_int mod;

  this->divmod (b, uns, code, &mod);
  return mod;
}

/* The same as double_int::mod with UNS = false.  */

double_int
double_int::smod (double_int b, unsigned code) const
{
  return this->mod (b, false, code);
}

/* The same as double_int::mod with UNS = true.  */

double_int
double_int::umod (double_int b, unsigned code) const
{
  return this->mod (b, true, code);
}

/* Return TRUE iff PRODUCT is an integral multiple of FACTOR, and return
   the multiple in *MULTIPLE.  Otherwise return FALSE and leave *MULTIPLE
   unchanged.  */

bool
double_int::multiple_of (double_int factor,
			 bool unsigned_p, double_int *multiple) const
{
  double_int remainder;
  double_int quotient = this->divmod (factor, unsigned_p,
					   TRUNC_DIV_EXPR, &remainder);
  if (remainder.is_zero ())
    {
      *multiple = quotient;
      return true;
    }

  return false;
}

/* Set BITPOS bit in A.  */
double_int
double_int::set_bit (unsigned bitpos) const
{
  double_int a = *this;
  if (bitpos < HOST_BITS_PER_WIDE_INT)
    a.low |= HOST_WIDE_INT_1U << bitpos;
  else
    a.high |= HOST_WIDE_INT_1 <<  (bitpos - HOST_BITS_PER_WIDE_INT);
 
  return a;
}

/* Count trailing zeros in A.  */
int
double_int::trailing_zeros () const
{
  const double_int &a = *this;
  unsigned HOST_WIDE_INT w = a.low ? a.low : (unsigned HOST_WIDE_INT) a.high;
  unsigned bits = a.low ? 0 : HOST_BITS_PER_WIDE_INT;
  if (!w)
    return HOST_BITS_PER_DOUBLE_INT;
  bits += ctz_hwi (w);
  return bits;
}

/* Shift A left by COUNT places.  */

double_int
double_int::lshift (HOST_WIDE_INT count) const
{
  double_int ret;

  gcc_checking_assert (count >= 0);

  if (count >= HOST_BITS_PER_DOUBLE_INT)
    {
      /* Shifting by the host word size is undefined according to the
	 ANSI standard, so we must handle this as a special case.  */
      ret.high = 0;
      ret.low = 0;
    }
  else if (count >= HOST_BITS_PER_WIDE_INT)
    {
      ret.high = low << (count - HOST_BITS_PER_WIDE_INT);
      ret.low = 0;
    }
  else
    {
      ret.high = (((unsigned HOST_WIDE_INT) high << count)
	     | (low >> (HOST_BITS_PER_WIDE_INT - count - 1) >> 1));
      ret.low = low << count;
    }

  return ret;
}

/* Shift A right by COUNT places.  */

double_int
double_int::rshift (HOST_WIDE_INT count) const
{
  double_int ret;

  gcc_checking_assert (count >= 0);

  if (count >= HOST_BITS_PER_DOUBLE_INT)
    {
      /* Shifting by the host word size is undefined according to the
	 ANSI standard, so we must handle this as a special case.  */
      ret.high = 0;
      ret.low = 0;
    }
  else if (count >= HOST_BITS_PER_WIDE_INT)
    {
      ret.high = 0;
      ret.low
	= (unsigned HOST_WIDE_INT) (high >> (count - HOST_BITS_PER_WIDE_INT));
    }
  else
    {
      ret.high = high >> count;
      ret.low = ((low >> count)
		 | ((unsigned HOST_WIDE_INT) high
		    << (HOST_BITS_PER_WIDE_INT - count - 1) << 1));
    }

  return ret;
}

/* Shift A left by COUNT places keeping only PREC bits of result.  Shift
   right if COUNT is negative.  ARITH true specifies arithmetic shifting;
   otherwise use logical shift.  */

double_int
double_int::lshift (HOST_WIDE_INT count, unsigned int prec, bool arith) const
{
  double_int ret;
  if (count > 0)
    lshift_double (low, high, count, prec, &ret.low, &ret.high);
  else
    rshift_double (low, high, absu_hwi (count), prec, &ret.low, &ret.high, arith);
  return ret;
}

/* Shift A right by COUNT places keeping only PREC bits of result.  Shift
   left if COUNT is negative.  ARITH true specifies arithmetic shifting;
   otherwise use logical shift.  */

double_int
double_int::rshift (HOST_WIDE_INT count, unsigned int prec, bool arith) const
{
  double_int ret;
  if (count > 0)
    rshift_double (low, high, count, prec, &ret.low, &ret.high, arith);
  else
    lshift_double (low, high, absu_hwi (count), prec, &ret.low, &ret.high);
  return ret;
}

/* Arithmetic shift A left by COUNT places keeping only PREC bits of result.
   Shift right if COUNT is negative.  */

double_int
double_int::alshift (HOST_WIDE_INT count, unsigned int prec) const
{
  double_int r;
  if (count > 0)
    lshift_double (low, high, count, prec, &r.low, &r.high);
  else
    rshift_double (low, high, absu_hwi (count), prec, &r.low, &r.high, true);
  return r;
}

/* Arithmetic shift A right by COUNT places keeping only PREC bits of result.
   Shift left if COUNT is negative.  */

double_int
double_int::arshift (HOST_WIDE_INT count, unsigned int prec) const
{
  double_int r;
  if (count > 0)
    rshift_double (low, high, count, prec, &r.low, &r.high, true);
  else
    lshift_double (low, high, absu_hwi (count), prec, &r.low, &r.high);
  return r;
}

/* Logical shift A left by COUNT places keeping only PREC bits of result.
   Shift right if COUNT is negative.  */

double_int
double_int::llshift (HOST_WIDE_INT count, unsigned int prec) const
{
  double_int r;
  if (count > 0)
    lshift_double (low, high, count, prec, &r.low, &r.high);
  else
    rshift_double (low, high, absu_hwi (count), prec, &r.low, &r.high, false);
  return r;
}

/* Logical shift A right by COUNT places keeping only PREC bits of result.
   Shift left if COUNT is negative.  */

double_int
double_int::lrshift (HOST_WIDE_INT count, unsigned int prec) const
{
  double_int r;
  if (count > 0)
    rshift_double (low, high, count, prec, &r.low, &r.high, false);
  else
    lshift_double (low, high, absu_hwi (count), prec, &r.low, &r.high);
  return r;
}

/* Rotate  A left by COUNT places keeping only PREC bits of result.
   Rotate right if COUNT is negative.  */

double_int
double_int::lrotate (HOST_WIDE_INT count, unsigned int prec) const
{
  double_int t1, t2;

  count %= prec;
  if (count < 0)
    count += prec;

  t1 = this->llshift (count, prec);
  t2 = this->lrshift (prec - count, prec);

  return t1 | t2;
}

/* Rotate A rigth by COUNT places keeping only PREC bits of result.
   Rotate right if COUNT is negative.  */

double_int
double_int::rrotate (HOST_WIDE_INT count, unsigned int prec) const
{
  double_int t1, t2;

  count %= prec;
  if (count < 0)
    count += prec;

  t1 = this->lrshift (count, prec);
  t2 = this->llshift (prec - count, prec);

  return t1 | t2;
}

/* Returns -1 if A < B, 0 if A == B and 1 if A > B.  Signedness of the
   comparison is given by UNS.  */

int
double_int::cmp (double_int b, bool uns) const
{
  if (uns)
    return this->ucmp (b);
  else
    return this->scmp (b);
}

/* Compares two unsigned values A and B.  Returns -1 if A < B, 0 if A == B,
   and 1 if A > B.  */

int
double_int::ucmp (double_int b) const
{
  const double_int &a = *this;
  if ((unsigned HOST_WIDE_INT) a.high < (unsigned HOST_WIDE_INT) b.high)
    return -1;
  if ((unsigned HOST_WIDE_INT) a.high > (unsigned HOST_WIDE_INT) b.high)
    return 1;
  if (a.low < b.low)
    return -1;
  if (a.low > b.low)
    return 1;

  return 0;
}

/* Compares two signed values A and B.  Returns -1 if A < B, 0 if A == B,
   and 1 if A > B.  */

int
double_int::scmp (double_int b) const
{
  const double_int &a = *this;
  if (a.high < b.high)
    return -1;
  if (a.high > b.high)
    return 1;
  if (a.low < b.low)
    return -1;
  if (a.low > b.low)
    return 1;

  return 0;
}

/* Compares two unsigned values A and B for less-than.  */

bool
double_int::ult (double_int b) const
{
  if ((unsigned HOST_WIDE_INT) high < (unsigned HOST_WIDE_INT) b.high)
    return true;
  if ((unsigned HOST_WIDE_INT) high > (unsigned HOST_WIDE_INT) b.high)
    return false;
  if (low < b.low)
    return true;
  return false;
}

/* Compares two unsigned values A and B for less-than or equal-to.  */

bool
double_int::ule (double_int b) const
{
  if ((unsigned HOST_WIDE_INT) high < (unsigned HOST_WIDE_INT) b.high)
    return true;
  if ((unsigned HOST_WIDE_INT) high > (unsigned HOST_WIDE_INT) b.high)
    return false;
  if (low <= b.low)
    return true;
  return false;
}

/* Compares two unsigned values A and B for greater-than.  */

bool
double_int::ugt (double_int b) const
{
  if ((unsigned HOST_WIDE_INT) high > (unsigned HOST_WIDE_INT) b.high)
    return true;
  if ((unsigned HOST_WIDE_INT) high < (unsigned HOST_WIDE_INT) b.high)
    return false;
  if (low > b.low)
    return true;
  return false;
}

/* Compares two signed values A and B for less-than.  */

bool
double_int::slt (double_int b) const
{
  if (high < b.high)
    return true;
  if (high > b.high)
    return false;
  if (low < b.low)
    return true;
  return false;
}

/* Compares two signed values A and B for less-than or equal-to.  */

bool
double_int::sle (double_int b) const
{
  if (high < b.high)
    return true;
  if (high > b.high)
    return false;
  if (low <= b.low)
    return true;
  return false;
}

/* Compares two signed values A and B for greater-than.  */

bool
double_int::sgt (double_int b) const
{
  if (high > b.high)
    return true;
  if (high < b.high)
    return false;
  if (low > b.low)
    return true;
  return false;
}


/* Compares two values A and B.  Returns max value.  Signedness of the
   comparison is given by UNS.  */

double_int
double_int::max (double_int b, bool uns)
{
  return (this->cmp (b, uns) == 1) ? *this : b;
}

/* Compares two signed values A and B.  Returns max value.  */

double_int
double_int::smax (double_int b)
{
  return (this->scmp (b) == 1) ? *this : b;
}

/* Compares two unsigned values A and B.  Returns max value.  */

double_int
double_int::umax (double_int b)
{
  return (this->ucmp (b) == 1) ? *this : b;
}

/* Compares two values A and B.  Returns mix value.  Signedness of the
   comparison is given by UNS.  */

double_int
double_int::min (double_int b, bool uns)
{
  return (this->cmp (b, uns) == -1) ? *this : b;
}

/* Compares two signed values A and B.  Returns min value.  */

double_int
double_int::smin (double_int b)
{
  return (this->scmp (b) == -1) ? *this : b;
}

/* Compares two unsigned values A and B.  Returns min value.  */

double_int
double_int::umin (double_int b)
{
  return (this->ucmp (b) == -1) ? *this : b;
}

/* Splits last digit of *CST (taken as unsigned) in BASE and returns it.  */

static unsigned
double_int_split_digit (double_int *cst, unsigned base)
{
  unsigned HOST_WIDE_INT resl, reml;
  HOST_WIDE_INT resh, remh;

  div_and_round_double (FLOOR_DIV_EXPR, true, cst->low, cst->high, base, 0,
			&resl, &resh, &reml, &remh);
  cst->high = resh;
  cst->low = resl;

  return reml;
}

/* Dumps CST to FILE.  If UNS is true, CST is considered to be unsigned,
   otherwise it is signed.  */

void
dump_double_int (FILE *file, double_int cst, bool uns)
{
  unsigned digits[100], n;
  int i;

  if (cst.is_zero ())
    {
      fprintf (file, "0");
      return;
    }

  if (!uns && cst.is_negative ())
    {
      fprintf (file, "-");
      cst = -cst;
    }

  for (n = 0; !cst.is_zero (); n++)
    digits[n] = double_int_split_digit (&cst, 10);
  for (i = n - 1; i >= 0; i--)
    fprintf (file, "%u", digits[i]);
}


/* Sets RESULT to VAL, taken unsigned if UNS is true and as signed
   otherwise.  */

void
mpz_set_double_int (mpz_t result, double_int val, bool uns)
{
  bool negate = false;
  unsigned HOST_WIDE_INT vp[2];

  if (!uns && val.is_negative ())
    {
      negate = true;
      val = -val;
    }

  vp[0] = val.low;
  vp[1] = (unsigned HOST_WIDE_INT) val.high;
  mpz_import (result, 2, -1, sizeof (HOST_WIDE_INT), 0, 0, vp);

  if (negate)
    mpz_neg (result, result);
}

/* Returns VAL converted to TYPE.  If WRAP is true, then out-of-range
   values of VAL will be wrapped; otherwise, they will be set to the
   appropriate minimum or maximum TYPE bound.  */

double_int
mpz_get_double_int (const_tree type, mpz_t val, bool wrap)
{
  unsigned HOST_WIDE_INT *vp;
  size_t count, numb;
  double_int res;

  if (!wrap)
    {
      mpz_t min, max;

      mpz_init (min);
      mpz_init (max);
      get_type_static_bounds (type, min, max);

      if (mpz_cmp (val, min) < 0)
	mpz_set (val, min);
      else if (mpz_cmp (val, max) > 0)
	mpz_set (val, max);

      mpz_clear (min);
      mpz_clear (max);
    }

  /* Determine the number of unsigned HOST_WIDE_INT that are required
     for representing the value.  The code to calculate count is
     extracted from the GMP manual, section "Integer Import and Export":
     http://gmplib.org/manual/Integer-Import-and-Export.html  */
  numb = 8 * sizeof (HOST_WIDE_INT);
  count = (mpz_sizeinbase (val, 2) + numb-1) / numb;
  if (count < 2)
    count = 2;
  vp = (unsigned HOST_WIDE_INT *) alloca (count * sizeof (HOST_WIDE_INT));

  vp[0] = 0;
  vp[1] = 0;
  mpz_export (vp, &count, -1, sizeof (HOST_WIDE_INT), 0, 0, val);

  gcc_assert (wrap || count <= 2);

  res.low = vp[0];
  res.high = (HOST_WIDE_INT) vp[1];

  res = res.ext (TYPE_PRECISION (type), TYPE_UNSIGNED (type));
  if (mpz_sgn (val) < 0)
    res = -res;

  return res;
}