aboutsummaryrefslogtreecommitdiff
path: root/gcc/gcov-io.c
blob: f45c32cc1e5526ac6e5e2d14e8df8e3cb60d28e8 (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
/* File format for coverage information
   Copyright (C) 1996, 1997, 1998, 2000, 2002, 2003, 2004, 2005, 2007,
   2008  Free Software Foundation, Inc.
   Contributed by Bob Manson <manson@cygnus.com>.
   Completely remangled by Nathan Sidwell <nathan@codesourcery.com>.

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.

Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
<http://www.gnu.org/licenses/>.  */

/* Routines declared in gcov-io.h.  This file should be #included by
   another source file, after having #included gcov-io.h.  */

#if !IN_GCOV
static void gcov_write_block (unsigned);
static gcov_unsigned_t *gcov_write_words (unsigned);
#endif
static const gcov_unsigned_t *gcov_read_words (unsigned);
#if !IN_LIBGCOV
static void gcov_allocate (unsigned);
#endif

static inline gcov_unsigned_t from_file (gcov_unsigned_t value)
{
#if !IN_LIBGCOV
  if (gcov_var.endian)
    {
      value = (value >> 16) | (value << 16);
      value = ((value & 0xff00ff) << 8) | ((value >> 8) & 0xff00ff);
    }
#endif
  return value;
}

/* Open a gcov file. NAME is the name of the file to open and MODE
   indicates whether a new file should be created, or an existing file
   opened. If MODE is >= 0 an existing file will be opened, if
   possible, and if MODE is <= 0, a new file will be created. Use
   MODE=0 to attempt to reopen an existing file and then fall back on
   creating a new one.  If MODE < 0, the file will be opened in
   read-only mode.  Otherwise it will be opened for modification.
   Return zero on failure, >0 on opening an existing file and <0 on
   creating a new one.  */

GCOV_LINKAGE int
#if IN_LIBGCOV
gcov_open (const char *name)
#else
gcov_open (const char *name, int mode)
#endif
{
#if IN_LIBGCOV
  const int mode = 0;
#endif
#if GCOV_LOCKED
  struct flock s_flock;
  int fd;

  s_flock.l_whence = SEEK_SET;
  s_flock.l_start = 0;
  s_flock.l_len = 0; /* Until EOF.  */
  s_flock.l_pid = getpid ();
#endif

  gcc_assert (!gcov_var.file);
  gcov_var.start = 0;
  gcov_var.offset = gcov_var.length = 0;
  gcov_var.overread = -1u;
  gcov_var.error = 0;
#if !IN_LIBGCOV
  gcov_var.endian = 0;
#endif
#if GCOV_LOCKED
  if (mode > 0)
    {
      /* Read-only mode - acquire a read-lock.  */
      s_flock.l_type = F_RDLCK;
      /* pass mode (ignored) for compatibility */
      fd = open (name, O_RDONLY, S_IRUSR | S_IWUSR);
    }
  else
    {
      /* Write mode - acquire a write-lock.  */
      s_flock.l_type = F_WRLCK;
      fd = open (name, O_RDWR | O_CREAT, 0666);
    }
  if (fd < 0)
    return 0;

  while (fcntl (fd, F_SETLKW, &s_flock) && errno == EINTR)
    continue;

  gcov_var.file = fdopen (fd, (mode > 0) ? "rb" : "r+b");

  if (!gcov_var.file)
    {
      close (fd);
      return 0;
    }

  if (mode > 0)
    gcov_var.mode = 1;
  else if (mode == 0)
    {
      struct stat st;

      if (fstat (fd, &st) < 0)
	{
	  fclose (gcov_var.file);
	  gcov_var.file = 0;
	  return 0;
	}
      if (st.st_size != 0)
	gcov_var.mode = 1;
      else
	gcov_var.mode = mode * 2 + 1;
    }
  else
    gcov_var.mode = mode * 2 + 1;
#else
  if (mode >= 0)
    gcov_var.file = fopen (name, (mode > 0) ? "rb" : "r+b");

  if (gcov_var.file)
    gcov_var.mode = 1;
  else if (mode <= 0)
    {
      gcov_var.file = fopen (name, "w+b");
      if (gcov_var.file)
	gcov_var.mode = mode * 2 + 1;
    }
  if (!gcov_var.file)
    return 0;
#endif

  setbuf (gcov_var.file, (char *)0);

  return 1;
}

/* Close the current gcov file. Flushes data to disk. Returns nonzero
   on failure or error flag set.  */

GCOV_LINKAGE int
gcov_close (void)
{
  if (gcov_var.file)
    {
#if !IN_GCOV
      if (gcov_var.offset && gcov_var.mode < 0)
	gcov_write_block (gcov_var.offset);
#endif
      fclose (gcov_var.file);
      gcov_var.file = 0;
      gcov_var.length = 0;
    }
#if !IN_LIBGCOV
  free (gcov_var.buffer);
  gcov_var.alloc = 0;
  gcov_var.buffer = 0;
#endif
  gcov_var.mode = 0;
  return gcov_var.error;
}

#if !IN_LIBGCOV
/* Check if MAGIC is EXPECTED. Use it to determine endianness of the
   file. Returns +1 for same endian, -1 for other endian and zero for
   not EXPECTED.  */

GCOV_LINKAGE int
gcov_magic (gcov_unsigned_t magic, gcov_unsigned_t expected)
{
  if (magic == expected)
    return 1;
  magic = (magic >> 16) | (magic << 16);
  magic = ((magic & 0xff00ff) << 8) | ((magic >> 8) & 0xff00ff);
  if (magic == expected)
    {
      gcov_var.endian = 1;
      return -1;
    }
  return 0;
}
#endif

#if !IN_LIBGCOV
static void
gcov_allocate (unsigned length)
{
  size_t new_size = gcov_var.alloc;

  if (!new_size)
    new_size = GCOV_BLOCK_SIZE;
  new_size += length;
  new_size *= 2;

  gcov_var.alloc = new_size;
  gcov_var.buffer = XRESIZEVAR (gcov_unsigned_t, gcov_var.buffer, new_size << 2);
}
#endif

#if !IN_GCOV
/* Write out the current block, if needs be.  */

static void
gcov_write_block (unsigned size)
{
  if (fwrite (gcov_var.buffer, size << 2, 1, gcov_var.file) != 1)
    gcov_var.error = 1;
  gcov_var.start += size;
  gcov_var.offset -= size;
}

/* Allocate space to write BYTES bytes to the gcov file. Return a
   pointer to those bytes, or NULL on failure.  */

static gcov_unsigned_t *
gcov_write_words (unsigned words)
{
  gcov_unsigned_t *result;

  gcc_assert (gcov_var.mode < 0);
#if IN_LIBGCOV
  if (gcov_var.offset >= GCOV_BLOCK_SIZE)
    {
      gcov_write_block (GCOV_BLOCK_SIZE);
      if (gcov_var.offset)
	{
	  gcc_assert (gcov_var.offset == 1);
	  memcpy (gcov_var.buffer, gcov_var.buffer + GCOV_BLOCK_SIZE, 4);
	}
    }
#else
  if (gcov_var.offset + words > gcov_var.alloc)
    gcov_allocate (gcov_var.offset + words);
#endif
  result = &gcov_var.buffer[gcov_var.offset];
  gcov_var.offset += words;

  return result;
}

/* Write unsigned VALUE to coverage file.  Sets error flag
   appropriately.  */

GCOV_LINKAGE void
gcov_write_unsigned (gcov_unsigned_t value)
{
  gcov_unsigned_t *buffer = gcov_write_words (1);

  buffer[0] = value;
}

/* Write counter VALUE to coverage file.  Sets error flag
   appropriately.  */

#if IN_LIBGCOV
GCOV_LINKAGE void
gcov_write_counter (gcov_type value)
{
  gcov_unsigned_t *buffer = gcov_write_words (2);

  buffer[0] = (gcov_unsigned_t) value;
  if (sizeof (value) > sizeof (gcov_unsigned_t))
    buffer[1] = (gcov_unsigned_t) (value >> 32);
  else
    buffer[1] = 0;
}
#endif /* IN_LIBGCOV */

#if !IN_LIBGCOV
/* Write STRING to coverage file.  Sets error flag on file
   error, overflow flag on overflow */

GCOV_LINKAGE void
gcov_write_string (const char *string)
{
  unsigned length = 0;
  unsigned alloc = 0;
  gcov_unsigned_t *buffer;

  if (string)
    {
      length = strlen (string);
      alloc = (length + 4) >> 2;
    }

  buffer = gcov_write_words (1 + alloc);

  buffer[0] = alloc;
  buffer[alloc] = 0;
  memcpy (&buffer[1], string, length);
}
#endif

#if !IN_LIBGCOV
/* Write a tag TAG and reserve space for the record length. Return a
   value to be used for gcov_write_length.  */

GCOV_LINKAGE gcov_position_t
gcov_write_tag (gcov_unsigned_t tag)
{
  gcov_position_t result = gcov_var.start + gcov_var.offset;
  gcov_unsigned_t *buffer = gcov_write_words (2);

  buffer[0] = tag;
  buffer[1] = 0;

  return result;
}

/* Write a record length using POSITION, which was returned by
   gcov_write_tag.  The current file position is the end of the
   record, and is restored before returning.  Returns nonzero on
   overflow.  */

GCOV_LINKAGE void
gcov_write_length (gcov_position_t position)
{
  unsigned offset;
  gcov_unsigned_t length;
  gcov_unsigned_t *buffer;

  gcc_assert (gcov_var.mode < 0);
  gcc_assert (position + 2 <= gcov_var.start + gcov_var.offset);
  gcc_assert (position >= gcov_var.start);
  offset = position - gcov_var.start;
  length = gcov_var.offset - offset - 2;
  buffer = (gcov_unsigned_t *) &gcov_var.buffer[offset];
  buffer[1] = length;
  if (gcov_var.offset >= GCOV_BLOCK_SIZE)
    gcov_write_block (gcov_var.offset);
}

#else /* IN_LIBGCOV */

/* Write a tag TAG and length LENGTH.  */

GCOV_LINKAGE void
gcov_write_tag_length (gcov_unsigned_t tag, gcov_unsigned_t length)
{
  gcov_unsigned_t *buffer = gcov_write_words (2);

  buffer[0] = tag;
  buffer[1] = length;
}

/* Write a summary structure to the gcov file.  Return nonzero on
   overflow.  */

GCOV_LINKAGE void
gcov_write_summary (gcov_unsigned_t tag, const struct gcov_summary *summary)
{
  unsigned ix, h_ix, bv_ix, h_cnt = 0;
  const struct gcov_ctr_summary *csum;
  unsigned histo_bitvector[GCOV_HISTOGRAM_BITVECTOR_SIZE];

  /* Count number of non-zero histogram entries, and fill in a bit vector
     of non-zero indices. The histogram is only currently computed for arc
     counters.  */
  for (bv_ix = 0; bv_ix < GCOV_HISTOGRAM_BITVECTOR_SIZE; bv_ix++)
    histo_bitvector[bv_ix] = 0;
  csum = &summary->ctrs[GCOV_COUNTER_ARCS];
  for (h_ix = 0; h_ix < GCOV_HISTOGRAM_SIZE; h_ix++)
    {
      if (csum->histogram[h_ix].num_counters > 0)
        {
          histo_bitvector[h_ix / 32] |= 1 << (h_ix % 32);
          h_cnt++;
        }
    }
  gcov_write_tag_length (tag, GCOV_TAG_SUMMARY_LENGTH(h_cnt));
  gcov_write_unsigned (summary->checksum);
  for (csum = summary->ctrs, ix = GCOV_COUNTERS_SUMMABLE; ix--; csum++)
    {
      gcov_write_unsigned (csum->num);
      gcov_write_unsigned (csum->runs);
      gcov_write_counter (csum->sum_all);
      gcov_write_counter (csum->run_max);
      gcov_write_counter (csum->sum_max);
      if (ix != GCOV_COUNTER_ARCS)
        {
          for (bv_ix = 0; bv_ix < GCOV_HISTOGRAM_BITVECTOR_SIZE; bv_ix++)
            gcov_write_unsigned (0);
          continue;
        }
      for (bv_ix = 0; bv_ix < GCOV_HISTOGRAM_BITVECTOR_SIZE; bv_ix++)
        gcov_write_unsigned (histo_bitvector[bv_ix]);
      for (h_ix = 0; h_ix < GCOV_HISTOGRAM_SIZE; h_ix++)
        {
          if (!csum->histogram[h_ix].num_counters)
            continue;
          gcov_write_unsigned (csum->histogram[h_ix].num_counters);
          gcov_write_counter (csum->histogram[h_ix].min_value);
          gcov_write_counter (csum->histogram[h_ix].cum_value);
        }
    }
}
#endif /* IN_LIBGCOV */

#endif /*!IN_GCOV */

/* Return a pointer to read BYTES bytes from the gcov file. Returns
   NULL on failure (read past EOF).  */

static const gcov_unsigned_t *
gcov_read_words (unsigned words)
{
  const gcov_unsigned_t *result;
  unsigned excess = gcov_var.length - gcov_var.offset;

  gcc_assert (gcov_var.mode > 0);
  if (excess < words)
    {
      gcov_var.start += gcov_var.offset;
#if IN_LIBGCOV
      if (excess)
	{
	  gcc_assert (excess == 1);
	  memcpy (gcov_var.buffer, gcov_var.buffer + gcov_var.offset, 4);
	}
#else
      memmove (gcov_var.buffer, gcov_var.buffer + gcov_var.offset, excess * 4);
#endif
      gcov_var.offset = 0;
      gcov_var.length = excess;
#if IN_LIBGCOV
      gcc_assert (!gcov_var.length || gcov_var.length == 1);
      excess = GCOV_BLOCK_SIZE;
#else
      if (gcov_var.length + words > gcov_var.alloc)
	gcov_allocate (gcov_var.length + words);
      excess = gcov_var.alloc - gcov_var.length;
#endif
      excess = fread (gcov_var.buffer + gcov_var.length,
		      1, excess << 2, gcov_var.file) >> 2;
      gcov_var.length += excess;
      if (gcov_var.length < words)
	{
	  gcov_var.overread += words - gcov_var.length;
	  gcov_var.length = 0;
	  return 0;
	}
    }
  result = &gcov_var.buffer[gcov_var.offset];
  gcov_var.offset += words;
  return result;
}

/* Read unsigned value from a coverage file. Sets error flag on file
   error, overflow flag on overflow */

GCOV_LINKAGE gcov_unsigned_t
gcov_read_unsigned (void)
{
  gcov_unsigned_t value;
  const gcov_unsigned_t *buffer = gcov_read_words (1);

  if (!buffer)
    return 0;
  value = from_file (buffer[0]);
  return value;
}

/* Read counter value from a coverage file. Sets error flag on file
   error, overflow flag on overflow */

GCOV_LINKAGE gcov_type
gcov_read_counter (void)
{
  gcov_type value;
  const gcov_unsigned_t *buffer = gcov_read_words (2);

  if (!buffer)
    return 0;
  value = from_file (buffer[0]);
  if (sizeof (value) > sizeof (gcov_unsigned_t))
    value |= ((gcov_type) from_file (buffer[1])) << 32;
  else if (buffer[1])
    gcov_var.error = -1;

  return value;
}

/* Read string from coverage file. Returns a pointer to a static
   buffer, or NULL on empty string. You must copy the string before
   calling another gcov function.  */

#if !IN_LIBGCOV
GCOV_LINKAGE const char *
gcov_read_string (void)
{
  unsigned length = gcov_read_unsigned ();

  if (!length)
    return 0;

  return (const char *) gcov_read_words (length);
}
#endif

GCOV_LINKAGE void
gcov_read_summary (struct gcov_summary *summary)
{
  unsigned ix, h_ix, bv_ix, h_cnt = 0;
  struct gcov_ctr_summary *csum;
  unsigned histo_bitvector[GCOV_HISTOGRAM_BITVECTOR_SIZE];
  unsigned cur_bitvector;

  summary->checksum = gcov_read_unsigned ();
  for (csum = summary->ctrs, ix = GCOV_COUNTERS_SUMMABLE; ix--; csum++)
    {
      csum->num = gcov_read_unsigned ();
      csum->runs = gcov_read_unsigned ();
      csum->sum_all = gcov_read_counter ();
      csum->run_max = gcov_read_counter ();
      csum->sum_max = gcov_read_counter ();
      memset (csum->histogram, 0,
              sizeof (gcov_bucket_type) * GCOV_HISTOGRAM_SIZE);
      for (bv_ix = 0; bv_ix < GCOV_HISTOGRAM_BITVECTOR_SIZE; bv_ix++)
        {
          histo_bitvector[bv_ix] = gcov_read_unsigned ();
          h_cnt += __builtin_popcountll (histo_bitvector[bv_ix]);
        }
      bv_ix = 0;
      h_ix = 0;
      cur_bitvector = 0;
      while (h_cnt--)
        {
          /* Find the index corresponding to the next entry we will read in.
             First find the next non-zero bitvector and re-initialize
             the histogram index accordingly, then right shift and increment
             the index until we find a set bit.  */
          while (!cur_bitvector)
            {
              h_ix = bv_ix * 32;
              gcc_assert(bv_ix < GCOV_HISTOGRAM_BITVECTOR_SIZE);
              cur_bitvector = histo_bitvector[bv_ix++];
            }
          while (!(cur_bitvector & 0x1))
            {
              h_ix++;
              cur_bitvector >>= 1;
            }
          gcc_assert(h_ix < GCOV_HISTOGRAM_SIZE);

          csum->histogram[h_ix].num_counters = gcov_read_unsigned ();
          csum->histogram[h_ix].min_value = gcov_read_counter ();
          csum->histogram[h_ix].cum_value = gcov_read_counter ();
          /* Shift off the index we are done with and increment to the
             corresponding next histogram entry.  */
          cur_bitvector >>= 1;
          h_ix++;
        }
    }
}

#if !IN_LIBGCOV
/* Reset to a known position.  BASE should have been obtained from
   gcov_position, LENGTH should be a record length.  */

GCOV_LINKAGE void
gcov_sync (gcov_position_t base, gcov_unsigned_t length)
{
  gcc_assert (gcov_var.mode > 0);
  base += length;
  if (base - gcov_var.start <= gcov_var.length)
    gcov_var.offset = base - gcov_var.start;
  else
    {
      gcov_var.offset = gcov_var.length = 0;
      fseek (gcov_var.file, base << 2, SEEK_SET);
      gcov_var.start = ftell (gcov_var.file) >> 2;
    }
}
#endif

#if IN_LIBGCOV
/* Move to a given position in a gcov file.  */

GCOV_LINKAGE void
gcov_seek (gcov_position_t base)
{
  gcc_assert (gcov_var.mode < 0);
  if (gcov_var.offset)
    gcov_write_block (gcov_var.offset);
  fseek (gcov_var.file, base << 2, SEEK_SET);
  gcov_var.start = ftell (gcov_var.file) >> 2;
}
#endif

#if IN_GCOV > 0
/* Return the modification time of the current gcov file.  */

GCOV_LINKAGE time_t
gcov_time (void)
{
  struct stat status;

  if (fstat (fileno (gcov_var.file), &status))
    return 0;
  else
    return status.st_mtime;
}
#endif /* IN_GCOV */

#if !IN_GCOV
/* Determine the index into histogram for VALUE. */

#if IN_LIBGCOV
static unsigned
#else
GCOV_LINKAGE unsigned
#endif
gcov_histo_index (gcov_type value)
{
  gcov_type_unsigned v = (gcov_type_unsigned)value;
  unsigned r = 0;
  unsigned prev2bits = 0;

  /* Find index into log2 scale histogram, where each of the log2
     sized buckets is divided into 4 linear sub-buckets for better
     focus in the higher buckets.  */

  /* Find the place of the most-significant bit set.  */
  if (v > 0)
    r = 63 - __builtin_clzll (v);

  /* If at most the 2 least significant bits are set (value is
     0 - 3) then that value is our index into the lowest set of
     four buckets.  */
  if (r < 2)
    return (unsigned)value;

  gcc_assert (r < 64);

  /* Find the two next most significant bits to determine which
     of the four linear sub-buckets to select.  */
  prev2bits = (v >> (r - 2)) & 0x3;
  /* Finally, compose the final bucket index from the log2 index and
     the next 2 bits. The minimum r value at this point is 2 since we
     returned above if r was 2 or more, so the minimum bucket at this
     point is 4.  */
  return (r - 1) * 4 + prev2bits;
}

/* Merge SRC_HISTO into TGT_HISTO. The counters are assumed to be in
   the same relative order in both histograms, and are matched up
   and merged in reverse order. Each counter is assigned an equal portion of
   its entry's original cumulative counter value when computing the
   new merged cum_value.  */

static void gcov_histogram_merge (gcov_bucket_type *tgt_histo,
                                  gcov_bucket_type *src_histo)
{
  int src_i, tgt_i, tmp_i = 0;
  unsigned src_num, tgt_num, merge_num;
  gcov_type src_cum, tgt_cum, merge_src_cum, merge_tgt_cum, merge_cum;
  gcov_type merge_min;
  gcov_bucket_type tmp_histo[GCOV_HISTOGRAM_SIZE];
  int src_done = 0;

  memset(tmp_histo, 0, sizeof (gcov_bucket_type) * GCOV_HISTOGRAM_SIZE);

  /* Assume that the counters are in the same relative order in both
     histograms. Walk the histograms from largest to smallest entry,
     matching up and combining counters in order.  */
  src_num = 0;
  src_cum = 0;
  src_i = GCOV_HISTOGRAM_SIZE - 1;
  for (tgt_i = GCOV_HISTOGRAM_SIZE - 1; tgt_i >= 0 && !src_done; tgt_i--)
    {
      tgt_num = tgt_histo[tgt_i].num_counters;
      tgt_cum = tgt_histo[tgt_i].cum_value;
      /* Keep going until all of the target histogram's counters at this
         position have been matched and merged with counters from the
         source histogram.  */
      while (tgt_num > 0 && !src_done)
        {
          /* If this is either the first time through this loop or we just
             exhausted the previous non-zero source histogram entry, look
             for the next non-zero source histogram entry.  */
          if (!src_num)
            {
              /* Locate the next non-zero entry.  */
              while (src_i >= 0 && !src_histo[src_i].num_counters)
                src_i--;
              /* If source histogram has fewer counters, then just copy over the
                 remaining target counters and quit.  */
              if (src_i < 0)
                {
                  tmp_histo[tgt_i].num_counters += tgt_num;
                  tmp_histo[tgt_i].cum_value += tgt_cum;
                  if (!tmp_histo[tgt_i].min_value ||
                      tgt_histo[tgt_i].min_value < tmp_histo[tgt_i].min_value)
                    tmp_histo[tgt_i].min_value = tgt_histo[tgt_i].min_value;
                  while (--tgt_i >= 0)
                    {
                      tmp_histo[tgt_i].num_counters
                          += tgt_histo[tgt_i].num_counters;
                      tmp_histo[tgt_i].cum_value += tgt_histo[tgt_i].cum_value;
                      if (!tmp_histo[tgt_i].min_value ||
                          tgt_histo[tgt_i].min_value
                          < tmp_histo[tgt_i].min_value)
                        tmp_histo[tgt_i].min_value = tgt_histo[tgt_i].min_value;
                    }

                  src_done = 1;
                  break;
                }

              src_num = src_histo[src_i].num_counters;
              src_cum = src_histo[src_i].cum_value;
            }

          /* The number of counters to merge on this pass is the minimum
             of the remaining counters from the current target and source
             histogram entries.  */
          merge_num = tgt_num;
          if (src_num < merge_num)
            merge_num = src_num;

          /* The merged min_value is the sum of the min_values from target
             and source.  */
          merge_min = tgt_histo[tgt_i].min_value + src_histo[src_i].min_value;

          /* Compute the portion of source and target entries' cum_value
             that will be apportioned to the counters being merged.
             The total remaining cum_value from each entry is divided
             equally among the counters from that histogram entry if we
             are not merging all of them.  */
          merge_src_cum = src_cum;
          if (merge_num < src_num)
            merge_src_cum = merge_num * src_cum / src_num;
          merge_tgt_cum = tgt_cum;
          if (merge_num < tgt_num)
            merge_tgt_cum = merge_num * tgt_cum / tgt_num;
          /* The merged cum_value is the sum of the source and target
             components.  */
          merge_cum = merge_src_cum + merge_tgt_cum;

          /* Update the remaining number of counters and cum_value left
             to be merged from this source and target entry.  */
          src_cum -= merge_src_cum;
          tgt_cum -= merge_tgt_cum;
          src_num -= merge_num;
          tgt_num -= merge_num;

          /* The merged counters get placed in the new merged histogram
             at the entry for the merged min_value.  */
          tmp_i = gcov_histo_index(merge_min);
          gcc_assert (tmp_i < GCOV_HISTOGRAM_SIZE);
          tmp_histo[tmp_i].num_counters += merge_num;
          tmp_histo[tmp_i].cum_value += merge_cum;
          if (!tmp_histo[tmp_i].min_value ||
              merge_min < tmp_histo[tmp_i].min_value)
            tmp_histo[tmp_i].min_value = merge_min;

          /* Ensure the search for the next non-zero src_histo entry starts
             at the next smallest histogram bucket.  */
          if (!src_num)
            src_i--;
        }
    }

  gcc_assert (tgt_i < 0);

  /* In the case where there were more counters in the source histogram,
     accumulate the remaining unmerged cumulative counter values. Add
     those to the smallest non-zero target histogram entry. Otherwise,
     the total cumulative counter values in the histogram will be smaller
     than the sum_all stored in the summary, which will complicate
     computing the working set information from the histogram later on.  */
  if (src_num)
    src_i--;
  while (src_i >= 0)
    {
      src_cum += src_histo[src_i].cum_value;
      src_i--;
    }
  /* At this point, tmp_i should be the smallest non-zero entry in the
     tmp_histo.  */
  gcc_assert(tmp_i >= 0 && tmp_i < GCOV_HISTOGRAM_SIZE
             && tmp_histo[tmp_i].num_counters > 0);
  tmp_histo[tmp_i].cum_value += src_cum;

  /* Finally, copy the merged histogram into tgt_histo.  */
  memcpy(tgt_histo, tmp_histo, sizeof (gcov_bucket_type) * GCOV_HISTOGRAM_SIZE);
}
#endif /* !IN_GCOV */