aboutsummaryrefslogtreecommitdiff
path: root/gcc/stmt.c
blob: 17f43d14d88a993c85a9a99222d5b8c350cfe174 (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
/* Expands front end tree to back end RTL for GCC
   Copyright (C) 1987-2019 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/>.  */

/* This file handles the generation of rtl code from tree structure
   above the level of expressions, using subroutines in exp*.c and emit-rtl.c.
   The functions whose names start with `expand_' are called by the
   expander to generate RTL instructions for various kinds of constructs.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "backend.h"
#include "target.h"
#include "rtl.h"
#include "tree.h"
#include "gimple.h"
#include "cfghooks.h"
#include "predict.h"
#include "memmodel.h"
#include "tm_p.h"
#include "optabs.h"
#include "regs.h"
#include "emit-rtl.h"
#include "pretty-print.h"
#include "diagnostic-core.h"

#include "fold-const.h"
#include "varasm.h"
#include "stor-layout.h"
#include "dojump.h"
#include "explow.h"
#include "stmt.h"
#include "expr.h"
#include "langhooks.h"
#include "cfganal.h"
#include "tree-cfg.h"
#include "params.h"
#include "dumpfile.h"
#include "builtins.h"


/* Functions and data structures for expanding case statements.  */

/* Case label structure, used to hold info on labels within case
   statements.  We handle "range" labels; for a single-value label
   as in C, the high and low limits are the same.

   We start with a vector of case nodes sorted in ascending order, and
   the default label as the last element in the vector.

   Switch statements are expanded in jump table form.

*/

class simple_case_node
{
public:
  simple_case_node (tree low, tree high, tree code_label):
    m_low (low), m_high (high), m_code_label (code_label)
  {}

  /* Lowest index value for this label.  */
  tree m_low;
  /* Highest index value for this label.  */
  tree m_high;
  /* Label to jump to when node matches.  */
  tree m_code_label;
};

static bool check_unique_operand_names (tree, tree, tree);
static char *resolve_operand_name_1 (char *, tree, tree, tree);

/* Return the rtx-label that corresponds to a LABEL_DECL,
   creating it if necessary.  */

rtx_insn *
label_rtx (tree label)
{
  gcc_assert (TREE_CODE (label) == LABEL_DECL);

  if (!DECL_RTL_SET_P (label))
    {
      rtx_code_label *r = gen_label_rtx ();
      SET_DECL_RTL (label, r);
      if (FORCED_LABEL (label) || DECL_NONLOCAL (label))
	LABEL_PRESERVE_P (r) = 1;
    }

  return as_a <rtx_insn *> (DECL_RTL (label));
}

/* As above, but also put it on the forced-reference list of the
   function that contains it.  */
rtx_insn *
force_label_rtx (tree label)
{
  rtx_insn *ref = label_rtx (label);
  tree function = decl_function_context (label);

  gcc_assert (function);

  vec_safe_push (forced_labels, ref);
  return ref;
}

/* As label_rtx, but ensures (in check build), that returned value is
   an existing label (i.e. rtx with code CODE_LABEL).  */
rtx_code_label *
jump_target_rtx (tree label)
{
  return as_a <rtx_code_label *> (label_rtx (label));
}

/* Add an unconditional jump to LABEL as the next sequential instruction.  */

void
emit_jump (rtx label)
{
  do_pending_stack_adjust ();
  emit_jump_insn (targetm.gen_jump (label));
  emit_barrier ();
}

/* Handle goto statements and the labels that they can go to.  */

/* Specify the location in the RTL code of a label LABEL,
   which is a LABEL_DECL tree node.

   This is used for the kind of label that the user can jump to with a
   goto statement, and for alternatives of a switch or case statement.
   RTL labels generated for loops and conditionals don't go through here;
   they are generated directly at the RTL level, by other functions below.

   Note that this has nothing to do with defining label *names*.
   Languages vary in how they do that and what that even means.  */

void
expand_label (tree label)
{
  rtx_code_label *label_r = jump_target_rtx (label);

  do_pending_stack_adjust ();
  emit_label (label_r);
  if (DECL_NAME (label))
    LABEL_NAME (DECL_RTL (label)) = IDENTIFIER_POINTER (DECL_NAME (label));

  if (DECL_NONLOCAL (label))
    {
      expand_builtin_setjmp_receiver (NULL);
      nonlocal_goto_handler_labels
	= gen_rtx_INSN_LIST (VOIDmode, label_r,
			     nonlocal_goto_handler_labels);
    }

  if (FORCED_LABEL (label))
    vec_safe_push<rtx_insn *> (forced_labels, label_r);

  if (DECL_NONLOCAL (label) || FORCED_LABEL (label))
    maybe_set_first_label_num (label_r);
}

/* Parse the output constraint pointed to by *CONSTRAINT_P.  It is the
   OPERAND_NUMth output operand, indexed from zero.  There are NINPUTS
   inputs and NOUTPUTS outputs to this extended-asm.  Upon return,
   *ALLOWS_MEM will be TRUE iff the constraint allows the use of a
   memory operand.  Similarly, *ALLOWS_REG will be TRUE iff the
   constraint allows the use of a register operand.  And, *IS_INOUT
   will be true if the operand is read-write, i.e., if it is used as
   an input as well as an output.  If *CONSTRAINT_P is not in
   canonical form, it will be made canonical.  (Note that `+' will be
   replaced with `=' as part of this process.)

   Returns TRUE if all went well; FALSE if an error occurred.  */

bool
parse_output_constraint (const char **constraint_p, int operand_num,
			 int ninputs, int noutputs, bool *allows_mem,
			 bool *allows_reg, bool *is_inout)
{
  const char *constraint = *constraint_p;
  const char *p;

  /* Assume the constraint doesn't allow the use of either a register
     or memory.  */
  *allows_mem = false;
  *allows_reg = false;

  /* Allow the `=' or `+' to not be at the beginning of the string,
     since it wasn't explicitly documented that way, and there is a
     large body of code that puts it last.  Swap the character to
     the front, so as not to uglify any place else.  */
  p = strchr (constraint, '=');
  if (!p)
    p = strchr (constraint, '+');

  /* If the string doesn't contain an `=', issue an error
     message.  */
  if (!p)
    {
      error ("output operand constraint lacks %<=%>");
      return false;
    }

  /* If the constraint begins with `+', then the operand is both read
     from and written to.  */
  *is_inout = (*p == '+');

  /* Canonicalize the output constraint so that it begins with `='.  */
  if (p != constraint || *is_inout)
    {
      char *buf;
      size_t c_len = strlen (constraint);

      if (p != constraint)
	warning (0, "output constraint %qc for operand %d "
		 "is not at the beginning",
		 *p, operand_num);

      /* Make a copy of the constraint.  */
      buf = XALLOCAVEC (char, c_len + 1);
      strcpy (buf, constraint);
      /* Swap the first character and the `=' or `+'.  */
      buf[p - constraint] = buf[0];
      /* Make sure the first character is an `='.  (Until we do this,
	 it might be a `+'.)  */
      buf[0] = '=';
      /* Replace the constraint with the canonicalized string.  */
      *constraint_p = ggc_alloc_string (buf, c_len);
      constraint = *constraint_p;
    }

  /* Loop through the constraint string.  */
  for (p = constraint + 1; *p; )
    {
      switch (*p)
	{
	case '+':
	case '=':
	  error ("operand constraint contains incorrectly positioned "
		 "%<+%> or %<=%>");
	  return false;

	case '%':
	  if (operand_num + 1 == ninputs + noutputs)
	    {
	      error ("%<%%%> constraint used with last operand");
	      return false;
	    }
	  break;

	case '?':  case '!':  case '*':  case '&':  case '#':
	case '$':  case '^':
	case 'E':  case 'F':  case 'G':  case 'H':
	case 's':  case 'i':  case 'n':
	case 'I':  case 'J':  case 'K':  case 'L':  case 'M':
	case 'N':  case 'O':  case 'P':  case ',':
	  break;

	case '0':  case '1':  case '2':  case '3':  case '4':
	case '5':  case '6':  case '7':  case '8':  case '9':
	case '[':
	  error ("matching constraint not valid in output operand");
	  return false;

	case '<':  case '>':
	  /* ??? Before flow, auto inc/dec insns are not supposed to exist,
	     excepting those that expand_call created.  So match memory
	     and hope.  */
	  *allows_mem = true;
	  break;

	case 'g':  case 'X':
	  *allows_reg = true;
	  *allows_mem = true;
	  break;

	default:
	  if (!ISALPHA (*p))
	    break;
	  enum constraint_num cn = lookup_constraint (p);
	  if (reg_class_for_constraint (cn) != NO_REGS
	      || insn_extra_address_constraint (cn))
	    *allows_reg = true;
	  else if (insn_extra_memory_constraint (cn))
	    *allows_mem = true;
	  else
	    insn_extra_constraint_allows_reg_mem (cn, allows_reg, allows_mem);
	  break;
	}

      for (size_t len = CONSTRAINT_LEN (*p, p); len; len--, p++)
	if (*p == '\0')
	  break;
    }

  return true;
}

/* Similar, but for input constraints.  */

bool
parse_input_constraint (const char **constraint_p, int input_num,
			int ninputs, int noutputs, int ninout,
			const char * const * constraints,
			bool *allows_mem, bool *allows_reg)
{
  const char *constraint = *constraint_p;
  const char *orig_constraint = constraint;
  size_t c_len = strlen (constraint);
  size_t j;
  bool saw_match = false;

  /* Assume the constraint doesn't allow the use of either
     a register or memory.  */
  *allows_mem = false;
  *allows_reg = false;

  /* Make sure constraint has neither `=', `+', nor '&'.  */

  for (j = 0; j < c_len; j += CONSTRAINT_LEN (constraint[j], constraint+j))
    switch (constraint[j])
      {
      case '+':  case '=':  case '&':
	if (constraint == orig_constraint)
	  {
	    error ("input operand constraint contains %qc", constraint[j]);
	    return false;
	  }
	break;

      case '%':
	if (constraint == orig_constraint
	    && input_num + 1 == ninputs - ninout)
	  {
	    error ("%<%%%> constraint used with last operand");
	    return false;
	  }
	break;

      case '<':  case '>':
      case '?':  case '!':  case '*':  case '#':
      case '$':  case '^':
      case 'E':  case 'F':  case 'G':  case 'H':
      case 's':  case 'i':  case 'n':
      case 'I':  case 'J':  case 'K':  case 'L':  case 'M':
      case 'N':  case 'O':  case 'P':  case ',':
	break;

	/* Whether or not a numeric constraint allows a register is
	   decided by the matching constraint, and so there is no need
	   to do anything special with them.  We must handle them in
	   the default case, so that we don't unnecessarily force
	   operands to memory.  */
      case '0':  case '1':  case '2':  case '3':  case '4':
      case '5':  case '6':  case '7':  case '8':  case '9':
	{
	  char *end;
	  unsigned long match;

	  saw_match = true;

	  match = strtoul (constraint + j, &end, 10);
	  if (match >= (unsigned long) noutputs)
	    {
	      error ("matching constraint references invalid operand number");
	      return false;
	    }

	  /* Try and find the real constraint for this dup.  Only do this
	     if the matching constraint is the only alternative.  */
	  if (*end == '\0'
	      && (j == 0 || (j == 1 && constraint[0] == '%')))
	    {
	      constraint = constraints[match];
	      *constraint_p = constraint;
	      c_len = strlen (constraint);
	      j = 0;
	      /* ??? At the end of the loop, we will skip the first part of
		 the matched constraint.  This assumes not only that the
		 other constraint is an output constraint, but also that
		 the '=' or '+' come first.  */
	      break;
	    }
	  else
	    j = end - constraint;
	  /* Anticipate increment at end of loop.  */
	  j--;
	}
	/* Fall through.  */

      case 'g':  case 'X':
	*allows_reg = true;
	*allows_mem = true;
	break;

      default:
	if (! ISALPHA (constraint[j]))
	  {
	    error ("invalid punctuation %qc in constraint", constraint[j]);
	    return false;
	  }
	enum constraint_num cn = lookup_constraint (constraint + j);
	if (reg_class_for_constraint (cn) != NO_REGS
	    || insn_extra_address_constraint (cn))
	  *allows_reg = true;
	else if (insn_extra_memory_constraint (cn)
		 || insn_extra_special_memory_constraint (cn))
	  *allows_mem = true;
	else
	  insn_extra_constraint_allows_reg_mem (cn, allows_reg, allows_mem);
	break;
      }

  if (saw_match && !*allows_reg)
    warning (0, "matching constraint does not allow a register");

  return true;
}

/* Return DECL iff there's an overlap between *REGS and DECL, where DECL
   can be an asm-declared register.  Called via walk_tree.  */

static tree
decl_overlaps_hard_reg_set_p (tree *declp, int *walk_subtrees ATTRIBUTE_UNUSED,
			      void *data)
{
  tree decl = *declp;
  const HARD_REG_SET *const regs = (const HARD_REG_SET *) data;

  if (VAR_P (decl))
    {
      if (DECL_HARD_REGISTER (decl)
	  && REG_P (DECL_RTL (decl))
	  && REGNO (DECL_RTL (decl)) < FIRST_PSEUDO_REGISTER)
	{
	  rtx reg = DECL_RTL (decl);

	  if (overlaps_hard_reg_set_p (*regs, GET_MODE (reg), REGNO (reg)))
	    return decl;
	}
      walk_subtrees = 0;
    }
  else if (TYPE_P (decl) || TREE_CODE (decl) == PARM_DECL)
    walk_subtrees = 0;
  return NULL_TREE;
}

/* If there is an overlap between *REGS and DECL, return the first overlap
   found.  */
tree
tree_overlaps_hard_reg_set (tree decl, HARD_REG_SET *regs)
{
  return walk_tree (&decl, decl_overlaps_hard_reg_set_p, regs, NULL);
}


/* A subroutine of expand_asm_operands.  Check that all operand names
   are unique.  Return true if so.  We rely on the fact that these names
   are identifiers, and so have been canonicalized by get_identifier,
   so all we need are pointer comparisons.  */

static bool
check_unique_operand_names (tree outputs, tree inputs, tree labels)
{
  tree i, j, i_name = NULL_TREE;

  for (i = outputs; i ; i = TREE_CHAIN (i))
    {
      i_name = TREE_PURPOSE (TREE_PURPOSE (i));
      if (! i_name)
	continue;

      for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
	if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
	  goto failure;
    }

  for (i = inputs; i ; i = TREE_CHAIN (i))
    {
      i_name = TREE_PURPOSE (TREE_PURPOSE (i));
      if (! i_name)
	continue;

      for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
	if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
	  goto failure;
      for (j = outputs; j ; j = TREE_CHAIN (j))
	if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
	  goto failure;
    }

  for (i = labels; i ; i = TREE_CHAIN (i))
    {
      i_name = TREE_PURPOSE (i);
      if (! i_name)
	continue;

      for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
	if (simple_cst_equal (i_name, TREE_PURPOSE (j)))
	  goto failure;
      for (j = inputs; j ; j = TREE_CHAIN (j))
	if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
	  goto failure;
    }

  return true;

 failure:
  error ("duplicate %<asm%> operand name %qs", TREE_STRING_POINTER (i_name));
  return false;
}

/* Resolve the names of the operands in *POUTPUTS and *PINPUTS to numbers,
   and replace the name expansions in STRING and in the constraints to
   those numbers.  This is generally done in the front end while creating
   the ASM_EXPR generic tree that eventually becomes the GIMPLE_ASM.  */

tree
resolve_asm_operand_names (tree string, tree outputs, tree inputs, tree labels)
{
  char *buffer;
  char *p;
  const char *c;
  tree t;

  check_unique_operand_names (outputs, inputs, labels);

  /* Substitute [<name>] in input constraint strings.  There should be no
     named operands in output constraints.  */
  for (t = inputs; t ; t = TREE_CHAIN (t))
    {
      c = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t)));
      if (strchr (c, '[') != NULL)
	{
	  p = buffer = xstrdup (c);
	  while ((p = strchr (p, '[')) != NULL)
	    p = resolve_operand_name_1 (p, outputs, inputs, NULL);
	  TREE_VALUE (TREE_PURPOSE (t))
	    = build_string (strlen (buffer), buffer);
	  free (buffer);
	}
    }

  /* Now check for any needed substitutions in the template.  */
  c = TREE_STRING_POINTER (string);
  while ((c = strchr (c, '%')) != NULL)
    {
      if (c[1] == '[')
	break;
      else if (ISALPHA (c[1]) && c[2] == '[')
	break;
      else
	{
	  c += 1 + (c[1] == '%');
	  continue;
	}
    }

  if (c)
    {
      /* OK, we need to make a copy so we can perform the substitutions.
	 Assume that we will not need extra space--we get to remove '['
	 and ']', which means we cannot have a problem until we have more
	 than 999 operands.  */
      buffer = xstrdup (TREE_STRING_POINTER (string));
      p = buffer + (c - TREE_STRING_POINTER (string));

      while ((p = strchr (p, '%')) != NULL)
	{
	  if (p[1] == '[')
	    p += 1;
	  else if (ISALPHA (p[1]) && p[2] == '[')
	    p += 2;
	  else
	    {
	      p += 1 + (p[1] == '%');
	      continue;
	    }

	  p = resolve_operand_name_1 (p, outputs, inputs, labels);
	}

      string = build_string (strlen (buffer), buffer);
      free (buffer);
    }

  return string;
}

/* A subroutine of resolve_operand_names.  P points to the '[' for a
   potential named operand of the form [<name>].  In place, replace
   the name and brackets with a number.  Return a pointer to the
   balance of the string after substitution.  */

static char *
resolve_operand_name_1 (char *p, tree outputs, tree inputs, tree labels)
{
  char *q;
  int op;
  tree t;

  /* Collect the operand name.  */
  q = strchr (++p, ']');
  if (!q)
    {
      error ("missing close brace for named operand");
      return strchr (p, '\0');
    }
  *q = '\0';

  /* Resolve the name to a number.  */
  for (op = 0, t = outputs; t ; t = TREE_CHAIN (t), op++)
    {
      tree name = TREE_PURPOSE (TREE_PURPOSE (t));
      if (name && strcmp (TREE_STRING_POINTER (name), p) == 0)
	goto found;
    }
  for (t = inputs; t ; t = TREE_CHAIN (t), op++)
    {
      tree name = TREE_PURPOSE (TREE_PURPOSE (t));
      if (name && strcmp (TREE_STRING_POINTER (name), p) == 0)
	goto found;
    }
  for (t = labels; t ; t = TREE_CHAIN (t), op++)
    {
      tree name = TREE_PURPOSE (t);
      if (name && strcmp (TREE_STRING_POINTER (name), p) == 0)
	goto found;
    }

  error ("undefined named operand %qs", identifier_to_locale (p));
  op = 0;

 found:
  /* Replace the name with the number.  Unfortunately, not all libraries
     get the return value of sprintf correct, so search for the end of the
     generated string by hand.  */
  sprintf (--p, "%d", op);
  p = strchr (p, '\0');

  /* Verify the no extra buffer space assumption.  */
  gcc_assert (p <= q);

  /* Shift the rest of the buffer down to fill the gap.  */
  memmove (p, q + 1, strlen (q + 1) + 1);

  return p;
}


/* Generate RTL to return directly from the current function.
   (That is, we bypass any return value.)  */

void
expand_naked_return (void)
{
  rtx_code_label *end_label;

  clear_pending_stack_adjust ();
  do_pending_stack_adjust ();

  end_label = naked_return_label;
  if (end_label == 0)
    end_label = naked_return_label = gen_label_rtx ();

  emit_jump (end_label);
}

/* Generate code to jump to LABEL if OP0 and OP1 are equal in mode MODE. PROB
   is the probability of jumping to LABEL.  */
static void
do_jump_if_equal (machine_mode mode, rtx op0, rtx op1, rtx_code_label *label,
		  int unsignedp, profile_probability prob)
{
  do_compare_rtx_and_jump (op0, op1, EQ, unsignedp, mode,
			   NULL_RTX, NULL, label, prob);
}

/* Return the sum of probabilities of outgoing edges of basic block BB.  */

static profile_probability
get_outgoing_edge_probs (basic_block bb)
{
  edge e;
  edge_iterator ei;
  profile_probability prob_sum = profile_probability::never ();
  if (!bb)
    return profile_probability::never ();
  FOR_EACH_EDGE (e, ei, bb->succs)
    prob_sum += e->probability;
  return prob_sum;
}

/* Computes the conditional probability of jumping to a target if the branch
   instruction is executed.
   TARGET_PROB is the estimated probability of jumping to a target relative
   to some basic block BB.
   BASE_PROB is the probability of reaching the branch instruction relative
   to the same basic block BB.  */

static inline profile_probability
conditional_probability (profile_probability target_prob,
			 profile_probability base_prob)
{
  return target_prob / base_prob;
}

/* Generate a dispatch tabler, switching on INDEX_EXPR and jumping to
   one of the labels in CASE_LIST or to the DEFAULT_LABEL.
   MINVAL, MAXVAL, and RANGE are the extrema and range of the case
   labels in CASE_LIST. STMT_BB is the basic block containing the statement.

   First, a jump insn is emitted.  First we try "casesi".  If that
   fails, try "tablejump".   A target *must* have one of them (or both).

   Then, a table with the target labels is emitted.

   The process is unaware of the CFG.  The caller has to fix up
   the CFG itself.  This is done in cfgexpand.c.  */     

static void
emit_case_dispatch_table (tree index_expr, tree index_type,
			  auto_vec<simple_case_node> &case_list,
			  rtx default_label,
			  edge default_edge,  tree minval, tree maxval,
			  tree range, basic_block stmt_bb)
{
  int i, ncases;
  rtx *labelvec;
  rtx_insn *fallback_label = label_rtx (case_list[0].m_code_label);
  rtx_code_label *table_label = gen_label_rtx ();
  bool has_gaps = false;
  profile_probability default_prob = default_edge ? default_edge->probability
						  : profile_probability::never ();
  profile_probability base = get_outgoing_edge_probs (stmt_bb);
  bool try_with_tablejump = false;

  profile_probability new_default_prob = conditional_probability (default_prob,
								  base);

  if (! try_casesi (index_type, index_expr, minval, range,
		    table_label, default_label, fallback_label,
                    new_default_prob))
    {
      /* Index jumptables from zero for suitable values of minval to avoid
	 a subtraction.  For the rationale see:
	 "http://gcc.gnu.org/ml/gcc-patches/2001-10/msg01234.html".  */
      if (optimize_insn_for_speed_p ()
	  && compare_tree_int (minval, 0) > 0
	  && compare_tree_int (minval, 3) < 0)
	{
	  minval = build_int_cst (index_type, 0);
	  range = maxval;
          has_gaps = true;
	}
      try_with_tablejump = true;
    }

  /* Get table of labels to jump to, in order of case index.  */

  ncases = tree_to_shwi (range) + 1;
  labelvec = XALLOCAVEC (rtx, ncases);
  memset (labelvec, 0, ncases * sizeof (rtx));

  for (unsigned j = 0; j < case_list.length (); j++)
    {
      simple_case_node *n = &case_list[j];
      /* Compute the low and high bounds relative to the minimum
	 value since that should fit in a HOST_WIDE_INT while the
	 actual values may not.  */
      HOST_WIDE_INT i_low
	= tree_to_uhwi (fold_build2 (MINUS_EXPR, index_type,
				     n->m_low, minval));
      HOST_WIDE_INT i_high
	= tree_to_uhwi (fold_build2 (MINUS_EXPR, index_type,
				     n->m_high, minval));
      HOST_WIDE_INT i;

      for (i = i_low; i <= i_high; i ++)
	labelvec[i]
	  = gen_rtx_LABEL_REF (Pmode, label_rtx (n->m_code_label));
    }

  /* The dispatch table may contain gaps, including at the beginning of
     the table if we tried to avoid the minval subtraction.  We fill the
     dispatch table slots associated with the gaps with the default case label.
     However, in the event the default case is unreachable, we then use
     any label from one of the case statements.  */
  rtx gap_label = (default_label) ? default_label : fallback_label;

  for (i = 0; i < ncases; i++)
    if (labelvec[i] == 0)
      {
	has_gaps = true;
	labelvec[i] = gen_rtx_LABEL_REF (Pmode, gap_label);
      }

  if (has_gaps && default_label)
    {
      /* There is at least one entry in the jump table that jumps
         to default label. The default label can either be reached
         through the indirect jump or the direct conditional jump
         before that. Split the probability of reaching the
         default label among these two jumps.  */
      new_default_prob
	= conditional_probability (default_prob.apply_scale (1, 2), base);
      default_prob = default_prob.apply_scale (1, 2);
      base -= default_prob;
    }
  else
    {
      base -= default_prob;
      default_prob = profile_probability::never ();
    }

  if (default_edge)
    default_edge->probability = default_prob;

  /* We have altered the probability of the default edge. So the probabilities
     of all other edges need to be adjusted so that it sums up to
     REG_BR_PROB_BASE.  */
  if (base > profile_probability::never ())
    {
      edge e;
      edge_iterator ei;
      FOR_EACH_EDGE (e, ei, stmt_bb->succs)
        e->probability /= base;
    }

  if (try_with_tablejump)
    {
      bool ok = try_tablejump (index_type, index_expr, minval, range,
                               table_label, default_label, new_default_prob);
      gcc_assert (ok);
    }
  /* Output the table.  */
  emit_label (table_label);

  if (CASE_VECTOR_PC_RELATIVE
	  || (flag_pic && targetm.asm_out.generate_pic_addr_diff_vec ()))
    emit_jump_table_data (gen_rtx_ADDR_DIFF_VEC (CASE_VECTOR_MODE,
						 gen_rtx_LABEL_REF (Pmode,
								    table_label),
						 gen_rtvec_v (ncases, labelvec),
						 const0_rtx, const0_rtx));
  else
    emit_jump_table_data (gen_rtx_ADDR_VEC (CASE_VECTOR_MODE,
					    gen_rtvec_v (ncases, labelvec)));

  /* Record no drop-through after the table.  */
  emit_barrier ();
}

/* Terminate a case Ada or switch (C) statement
   in which ORIG_INDEX is the expression to be tested.
   If ORIG_TYPE is not NULL, it is the original ORIG_INDEX
   type as given in the source before any compiler conversions.
   Generate the code to test it and jump to the right place.  */

void
expand_case (gswitch *stmt)
{
  tree minval = NULL_TREE, maxval = NULL_TREE, range = NULL_TREE;
  rtx_code_label *default_label;
  unsigned int count;
  int i;
  int ncases = gimple_switch_num_labels (stmt);
  tree index_expr = gimple_switch_index (stmt);
  tree index_type = TREE_TYPE (index_expr);
  tree elt;
  basic_block bb = gimple_bb (stmt);
  gimple *def_stmt;

  auto_vec<simple_case_node> case_list;

  /* An ERROR_MARK occurs for various reasons including invalid data type.
     ??? Can this still happen, with GIMPLE and all?  */
  if (index_type == error_mark_node)
    return;

  /* cleanup_tree_cfg removes all SWITCH_EXPR with their index
     expressions being INTEGER_CST.  */
  gcc_assert (TREE_CODE (index_expr) != INTEGER_CST);

  /* Optimization of switch statements with only one label has already
     occurred, so we should never see them at this point.  */
  gcc_assert (ncases > 1);

  do_pending_stack_adjust ();

  /* Find the default case target label.  */
  tree default_lab = CASE_LABEL (gimple_switch_default_label (stmt));
  default_label = jump_target_rtx (default_lab);
  basic_block default_bb = label_to_block (cfun, default_lab);
  edge default_edge = find_edge (bb, default_bb);

  /* Get upper and lower bounds of case values.  */
  elt = gimple_switch_label (stmt, 1);
  minval = fold_convert (index_type, CASE_LOW (elt));
  elt = gimple_switch_label (stmt, ncases - 1);
  if (CASE_HIGH (elt))
    maxval = fold_convert (index_type, CASE_HIGH (elt));
  else
    maxval = fold_convert (index_type, CASE_LOW (elt));

  /* Try to narrow the index type if it's larger than a word.
     That is mainly for -O0 where an equivalent optimization
     done by forward propagation is not run and is aimed at
     avoiding a call to a comparison routine of libgcc.  */
  if (TYPE_PRECISION (index_type) > BITS_PER_WORD
      && TREE_CODE (index_expr) == SSA_NAME
      && (def_stmt = SSA_NAME_DEF_STMT (index_expr))
      && is_gimple_assign (def_stmt)
      && gimple_assign_rhs_code (def_stmt) == NOP_EXPR)
    {
      tree inner_index_expr = gimple_assign_rhs1 (def_stmt);
      tree inner_index_type = TREE_TYPE (inner_index_expr);

      if (INTEGRAL_TYPE_P (inner_index_type)
	  && TYPE_PRECISION (inner_index_type) <= BITS_PER_WORD
	  && int_fits_type_p (minval, inner_index_type)
	  && int_fits_type_p (maxval, inner_index_type))
	{
	  index_expr = inner_index_expr;
	  index_type = inner_index_type;
	  minval = fold_convert (index_type, minval);
	  maxval = fold_convert (index_type, maxval);
	}
    }

  /* Compute span of values.  */
  range = fold_build2 (MINUS_EXPR, index_type, maxval, minval);

  /* Listify the labels queue and gather some numbers to decide
     how to expand this switch().  */
  count = 0;

  for (i = ncases - 1; i >= 1; --i)
    {
      elt = gimple_switch_label (stmt, i);
      tree low = CASE_LOW (elt);
      gcc_assert (low);
      tree high = CASE_HIGH (elt);
      gcc_assert (! high || tree_int_cst_lt (low, high));
      tree lab = CASE_LABEL (elt);

      /* Count the elements.
	 A range counts double, since it requires two compares.  */
      count++;
      if (high)
	count++;

      /* The bounds on the case range, LOW and HIGH, have to be converted
	 to case's index type TYPE.  Note that the original type of the
	 case index in the source code is usually "lost" during
	 gimplification due to type promotion, but the case labels retain the
	 original type.  Make sure to drop overflow flags.  */
      low = fold_convert (index_type, low);
      if (TREE_OVERFLOW (low))
	low = wide_int_to_tree (index_type, wi::to_wide (low));

      /* The canonical from of a case label in GIMPLE is that a simple case
	 has an empty CASE_HIGH.  For the casesi and tablejump expanders,
	 the back ends want simple cases to have high == low.  */
      if (! high)
	high = low;
      high = fold_convert (index_type, high);
      if (TREE_OVERFLOW (high))
	high = wide_int_to_tree (index_type, wi::to_wide (high));

      case_list.safe_push (simple_case_node (low, high, lab));
    }

  /* cleanup_tree_cfg removes all SWITCH_EXPR with a single
     destination, such as one with a default case only.
     It also removes cases that are out of range for the switch
     type, so we should never get a zero here.  */
  gcc_assert (count > 0);

  rtx_insn *before_case = get_last_insn ();

  /* If the default case is unreachable, then set default_label to NULL
     so that we omit the range check when generating the dispatch table.
     We also remove the edge to the unreachable default case.  The block
     itself will be automatically removed later.  */
  if (EDGE_COUNT (default_edge->dest->succs) == 0
      && gimple_seq_unreachable_p (bb_seq (default_edge->dest)))
    {
      default_label = NULL;
      remove_edge (default_edge);
      default_edge = NULL;
    }

  emit_case_dispatch_table (index_expr, index_type,
			    case_list, default_label, default_edge,
			    minval, maxval, range, bb);

  reorder_insns (NEXT_INSN (before_case), get_last_insn (), before_case);

  free_temp_slots ();
}

/* Expand the dispatch to a short decrement chain if there are few cases
   to dispatch to.  Likewise if neither casesi nor tablejump is available,
   or if flag_jump_tables is set.  Otherwise, expand as a casesi or a
   tablejump.  The index mode is always the mode of integer_type_node.
   Trap if no case matches the index.

   DISPATCH_INDEX is the index expression to switch on.  It should be a
   memory or register operand.
   
   DISPATCH_TABLE is a set of case labels.  The set should be sorted in
   ascending order, be contiguous, starting with value 0, and contain only
   single-valued case labels.  */

void
expand_sjlj_dispatch_table (rtx dispatch_index,
			    vec<tree> dispatch_table)
{
  tree index_type = integer_type_node;
  machine_mode index_mode = TYPE_MODE (index_type);

  int ncases = dispatch_table.length ();

  do_pending_stack_adjust ();
  rtx_insn *before_case = get_last_insn ();

  /* Expand as a decrement-chain if there are 5 or fewer dispatch
     labels.  This covers more than 98% of the cases in libjava,
     and seems to be a reasonable compromise between the "old way"
     of expanding as a decision tree or dispatch table vs. the "new
     way" with decrement chain or dispatch table.  */
  if (dispatch_table.length () <= 5
      || (!targetm.have_casesi () && !targetm.have_tablejump ())
      || !flag_jump_tables)
    {
      /* Expand the dispatch as a decrement chain:

	 "switch(index) {case 0: do_0; case 1: do_1; ...; case N: do_N;}"

	 ==>

	 if (index == 0) do_0; else index--;
	 if (index == 0) do_1; else index--;
	 ...
	 if (index == 0) do_N; else index--;

	 This is more efficient than a dispatch table on most machines.
	 The last "index--" is redundant but the code is trivially dead
	 and will be cleaned up by later passes.  */
      rtx index = copy_to_mode_reg (index_mode, dispatch_index);
      rtx zero = CONST0_RTX (index_mode);
      for (int i = 0; i < ncases; i++)
        {
	  tree elt = dispatch_table[i];
	  rtx_code_label *lab = jump_target_rtx (CASE_LABEL (elt));
	  do_jump_if_equal (index_mode, index, zero, lab, 0,
			    profile_probability::uninitialized ());
	  force_expand_binop (index_mode, sub_optab,
			      index, CONST1_RTX (index_mode),
			      index, 0, OPTAB_DIRECT);
	}
    }
  else
    {
      /* Similar to expand_case, but much simpler.  */
      auto_vec<simple_case_node> case_list;
      tree index_expr = make_tree (index_type, dispatch_index);
      tree minval = build_int_cst (index_type, 0);
      tree maxval = CASE_LOW (dispatch_table.last ());
      tree range = maxval;
      rtx_code_label *default_label = gen_label_rtx ();

      for (int i = ncases - 1; i >= 0; --i)
	{
	  tree elt = dispatch_table[i];
	  tree high = CASE_HIGH (elt);
	  if (high == NULL_TREE)
	    high = CASE_LOW (elt);
	  case_list.safe_push (simple_case_node (CASE_LOW (elt), high,
						 CASE_LABEL (elt)));
	}

      emit_case_dispatch_table (index_expr, index_type,
				case_list, default_label, NULL,
				minval, maxval, range,
				BLOCK_FOR_INSN (before_case));
      emit_label (default_label);
    }

  /* Dispatching something not handled?  Trap!  */
  expand_builtin_trap ();

  reorder_insns (NEXT_INSN (before_case), get_last_insn (), before_case);

  free_temp_slots ();
}