libgcc/libgcov-merge.c

   1 /* Routines required for instrumenting a program.  */
   2 /* Compile this one with gcc.  */
   3 /* Copyright (C) 1989-2020 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 Under Section 7 of GPL version 3, you are granted additional
  18 permissions described in the GCC Runtime Library Exception, version
  19 3.1, as published by the Free Software Foundation.
  20
  21 You should have received a copy of the GNU General Public License and
  22 a copy of the GCC Runtime Library Exception along with this program;
  23 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 <http://www.gnu.org/licenses/>.  */
  25
  26 #include "libgcov.h"
  27
  28 #if defined(inhibit_libc)
  29 /* If libc and its header files are not available, provide dummy functions.  */
  30
  31 #ifdef L_gcov_merge_add
  32 void __gcov_merge_add (gcov_type *counters  __attribute__ ((unused)),
  33                        unsigned n_counters __attribute__ ((unused))) {}
  34 #endif
  35
  36 #ifdef L_gcov_merge_topn
  37 void __gcov_merge_topn (gcov_type *counters  __attribute__ ((unused)),
  38                         unsigned n_counters __attribute__ ((unused))) {}
  39 #endif
  40
  41 #else
  42
  43 #ifdef L_gcov_merge_add
  44 /* The profile merging function that just adds the counters.  It is given
  45    an array COUNTERS of N_COUNTERS old counters and it reads the same number
  46    of counters from the gcov file.  */
  47 void
  48 __gcov_merge_add (gcov_type *counters, unsigned n_counters)
  49 {
  50   for (; n_counters; counters++, n_counters--)
  51     *counters += gcov_get_counter ();
  52 }
  53 #endif /* L_gcov_merge_add */
  54
  55 #ifdef L_gcov_merge_ior
  56 /* The profile merging function that just adds the counters.  It is given
  57    an array COUNTERS of N_COUNTERS old counters and it reads the same number
  58    of counters from the gcov file.  */
  59 void
  60 __gcov_merge_ior (gcov_type *counters, unsigned n_counters)
  61 {
  62   for (; n_counters; counters++, n_counters--)
  63     *counters |= gcov_get_counter_target ();
  64 }
  65 #endif
  66
  67 #ifdef L_gcov_merge_time_profile
  68 /* Time profiles are merged so that minimum from all valid (greater than zero)
  69    is stored. There could be a fork that creates new counters. To have
  70    the profile stable, we chosen to pick the smallest function visit time.  */
  71 void
  72 __gcov_merge_time_profile (gcov_type *counters, unsigned n_counters)
  73 {
  74   unsigned int i;
  75   gcov_type value;
  76
  77   for (i = 0; i < n_counters; i++)
  78     {
  79       value = gcov_get_counter_target ();
  80
  81       if (value && (!counters[i] || value < counters[i]))
  82         counters[i] = value;
  83     }
  84 }
  85 #endif /* L_gcov_merge_time_profile */
  86
  87 #ifdef L_gcov_merge_topn
  88
  89 /* To merging of TOPN profiles.
  90    counters[0] is the number of executions
  91    for i in 0 ... TOPN-1
  92      counters[2 * i + 1] is target
  93      counters[2 * i + 2] is corresponding hitrate counter.
  94
  95    Because we prune counters only those with probability >= 1/TOPN are
  96    present now.
  97
  98    We use sign of counters[0] to track whether the number of different
  99    targets exceeds TOPN.  */
 100
 101 static void
 102 merge_topn_values_set (gcov_type *counters)
 103 {
 104   /* First value is number of total executions of the profiler.  */
 105   gcov_type all = gcov_get_counter ();
 106   gcov_type *total = &counters[0];
 107   ++counters;
 108
 109   /* Negative value means that counter is missing some of values.  */
 110   if (all < 0)
 111     *total = -(*total);
 112
 113   *total += all;
 114
 115   /* Read all part values.  */
 116   gcov_type read_counters[2 * GCOV_TOPN_VALUES];
 117   for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
 118     {
 119       read_counters[2 * i] = gcov_get_counter_target ();
 120       read_counters[2 * i + 1] = gcov_get_counter_ignore_scaling (-1);
 121     }
 122
 123   for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
 124     {
 125       if (read_counters[2 * i + 1] == 0)
 126         continue;
 127
 128       unsigned j;
 129       int slot = 0;
 130
 131       for (j = 0; j < GCOV_TOPN_VALUES; j++)
 132         {
 133           if (counters[2 * j] == read_counters[2 * i])
 134             {
 135               counters[2 * j + 1] += read_counters[2 * i + 1];
 136               break;
 137             }
 138           else if (counters[2 * j + 1] < counters[2 * slot + 1])
 139             slot = j;
 140         }
 141
 142       if (j == GCOV_TOPN_VALUES)
 143         {
 144           gcov_type slot_count = counters[2 * slot + 1];
 145           /* We found an empty slot.  */
 146           if (slot_count == 0)
 147             {
 148               /* If we found empty slot, add the value.  */
 149               counters[2 * slot] = read_counters[2 * i];
 150               counters[2 * slot + 1] = read_counters[2 * i + 1];
 151             }
 152           else
 153             {
 154               /* Here we are loosing some values.  */
 155               if (*total >= 0)
 156                 *total = -(*total);
 157               if (read_counters[2 * i + 1] > slot_count)
 158                 {
 159                   counters[2 * slot] = read_counters[2 * i];
 160                   counters[2 * slot + 1] = read_counters[2 * i + 1];
 161                 }
 162               else
 163                 counters[2 * slot + 1] -= read_counters[2 * i + 1];
 164             }
 165         }
 166     }
 167 }
 168
 169 /* The profile merging function for choosing the most common value.
 170    It is given an array COUNTERS of N_COUNTERS old counters and it
 171    reads the same number of counters from the gcov file.  The counters
 172    are split into pairs where the members of the tuple have
 173    meanings:
 174
 175    -- the stored candidate on the most common value of the measured entity
 176    -- counter
 177    */
 178 void
 179 __gcov_merge_topn (gcov_type *counters, unsigned n_counters)
 180 {
 181   gcc_assert (!(n_counters % GCOV_TOPN_VALUES_COUNTERS));
 182
 183   for (unsigned i = 0; i < (n_counters / GCOV_TOPN_VALUES_COUNTERS); i++)
 184     merge_topn_values_set (counters + (i * GCOV_TOPN_VALUES_COUNTERS));
 185 }
 186 #endif /* L_gcov_merge_topn */
 187
 188 #endif /* inhibit_libc */