libgcc/libgcov-profiler.c

   1 /* Routines required for instrumenting a program.  */
   2 /* Compile this one with gcc.  */
   3 /* Copyright (C) 1989-2021 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 #if !defined(inhibit_libc)
  28
  29 #ifdef L_gcov_interval_profiler
  30 /* If VALUE is in interval <START, START + STEPS - 1>, then increases the
  31    corresponding counter in COUNTERS.  If the VALUE is above or below
  32    the interval, COUNTERS[STEPS] or COUNTERS[STEPS + 1] is increased
  33    instead.  */
  34
  35 void
  36 __gcov_interval_profiler (gcov_type *counters, gcov_type value,
  37                           int start, unsigned steps)
  38 {
  39   gcov_type delta = value - start;
  40   if (delta < 0)
  41     counters[steps + 1]++;
  42   else if (delta >= steps)
  43     counters[steps]++;
  44   else
  45     counters[delta]++;
  46 }
  47 #endif
  48
  49 #if defined(L_gcov_interval_profiler_atomic) && GCOV_SUPPORTS_ATOMIC
  50 /* If VALUE is in interval <START, START + STEPS - 1>, then increases the
  51    corresponding counter in COUNTERS.  If the VALUE is above or below
  52    the interval, COUNTERS[STEPS] or COUNTERS[STEPS + 1] is increased
  53    instead.  Function is thread-safe.  */
  54
  55 void
  56 __gcov_interval_profiler_atomic (gcov_type *counters, gcov_type value,
  57                                  int start, unsigned steps)
  58 {
  59   gcov_type delta = value - start;
  60   if (delta < 0)
  61     __atomic_fetch_add (&counters[steps + 1], 1, __ATOMIC_RELAXED);
  62   else if (delta >= steps)
  63     __atomic_fetch_add (&counters[steps], 1, __ATOMIC_RELAXED);
  64   else
  65     __atomic_fetch_add (&counters[delta], 1, __ATOMIC_RELAXED);
  66 }
  67 #endif
  68
  69 #ifdef L_gcov_pow2_profiler
  70 /* If VALUE is a power of two, COUNTERS[1] is incremented.  Otherwise
  71    COUNTERS[0] is incremented.  */
  72
  73 void
  74 __gcov_pow2_profiler (gcov_type *counters, gcov_type value)
  75 {
  76   if (value == 0 || (value & (value - 1)))
  77     counters[0]++;
  78   else
  79     counters[1]++;
  80 }
  81 #endif
  82
  83 #if defined(L_gcov_pow2_profiler_atomic) && GCOV_SUPPORTS_ATOMIC
  84 /* If VALUE is a power of two, COUNTERS[1] is incremented.  Otherwise
  85    COUNTERS[0] is incremented.  Function is thread-safe.  */
  86
  87 void
  88 __gcov_pow2_profiler_atomic (gcov_type *counters, gcov_type value)
  89 {
  90   if (value == 0 || (value & (value - 1)))
  91     __atomic_fetch_add (&counters[0], 1, __ATOMIC_RELAXED);
  92   else
  93     __atomic_fetch_add (&counters[1], 1, __ATOMIC_RELAXED);
  94 }
  95 #endif
  96
  97 /* Tries to determine N most commons value among its inputs.  */
  98
  99 static inline void
 100 __gcov_topn_values_profiler_body (gcov_type *counters, gcov_type value,
 101                                   int use_atomic)
 102 {
 103   gcov_topn_add_value (counters, value, 1, use_atomic, 1);
 104 }
 105
 106 #ifdef L_gcov_topn_values_profiler
 107 void
 108 __gcov_topn_values_profiler (gcov_type *counters, gcov_type value)
 109 {
 110   __gcov_topn_values_profiler_body (counters, value, 0);
 111 }
 112 #endif
 113
 114 #if defined(L_gcov_topn_values_profiler_atomic) && GCOV_SUPPORTS_ATOMIC
 115
 116 /* Update one value profilers (COUNTERS) for a given VALUE.
 117
 118    CAVEAT: Following function is not thread-safe, only total number
 119    of executions (COUNTERS[2]) is update with an atomic instruction.
 120    Problem is that one cannot atomically update two counters
 121    (COUNTERS[0] and COUNTERS[1]), for more information please read
 122    following email thread:
 123    https://gcc.gnu.org/ml/gcc-patches/2016-08/msg00024.html.  */
 124
 125 void
 126 __gcov_topn_values_profiler_atomic (gcov_type *counters, gcov_type value)
 127 {
 128   __gcov_topn_values_profiler_body (counters, value, 1);
 129 }
 130 #endif
 131
 132 #ifdef L_gcov_indirect_call_profiler_v4
 133
 134 /* These two variables are used to actually track caller and callee.  Keep
 135    them in TLS memory so races are not common (they are written to often).
 136    The variables are set directly by GCC instrumented code, so declaration
 137    here must match one in tree-profile.c  */
 138
 139 #if defined(HAVE_CC_TLS) && !defined (USE_EMUTLS)
 140 __thread
 141 #endif
 142 struct indirect_call_tuple __gcov_indirect_call;
 143
 144 /* By default, the C++ compiler will use function addresses in the
 145    vtable entries.  Setting TARGET_VTABLE_USES_DESCRIPTORS to nonzero
 146    tells the compiler to use function descriptors instead.  The value
 147    of this macro says how many words wide the descriptor is (normally 2).
 148
 149    It is assumed that the address of a function descriptor may be treated
 150    as a pointer to a function.  */
 151
 152 /* Tries to determine the most common value among its inputs. */
 153 static inline void
 154 __gcov_indirect_call_profiler_body (gcov_type value, void *cur_func,
 155                                     int use_atomic)
 156 {
 157   /* If the C++ virtual tables contain function descriptors then one
 158      function may have multiple descriptors and we need to dereference
 159      the descriptors to see if they point to the same function.  */
 160   if (cur_func == __gcov_indirect_call.callee
 161       || (__LIBGCC_VTABLE_USES_DESCRIPTORS__
 162           && *(void **) cur_func == *(void **) __gcov_indirect_call.callee))
 163     __gcov_topn_values_profiler_body (__gcov_indirect_call.counters, value,
 164                                       use_atomic);
 165
 166   __gcov_indirect_call.callee = NULL;
 167 }
 168
 169 void
 170 __gcov_indirect_call_profiler_v4 (gcov_type value, void *cur_func)
 171 {
 172   __gcov_indirect_call_profiler_body (value, cur_func, 0);
 173 }
 174
 175 #if GCOV_SUPPORTS_ATOMIC
 176 void
 177 __gcov_indirect_call_profiler_v4_atomic (gcov_type value, void *cur_func)
 178 {
 179   __gcov_indirect_call_profiler_body (value, cur_func, 1);
 180 }
 181 #endif
 182
 183 #endif
 184
 185 #ifdef L_gcov_time_profiler
 186
 187 /* Counter for first visit of each function.  */
 188 gcov_type __gcov_time_profiler_counter ATTRIBUTE_HIDDEN;
 189
 190 #endif
 191
 192 #ifdef L_gcov_average_profiler
 193 /* Increase corresponding COUNTER by VALUE.  FIXME: Perhaps we want
 194    to saturate up.  */
 195
 196 void
 197 __gcov_average_profiler (gcov_type *counters, gcov_type value)
 198 {
 199   counters[0] += value;
 200   counters[1] ++;
 201 }
 202 #endif
 203
 204 #if defined(L_gcov_average_profiler_atomic) && GCOV_SUPPORTS_ATOMIC
 205 /* Increase corresponding COUNTER by VALUE.  FIXME: Perhaps we want
 206    to saturate up.  Function is thread-safe.  */
 207
 208 void
 209 __gcov_average_profiler_atomic (gcov_type *counters, gcov_type value)
 210 {
 211   __atomic_fetch_add (&counters[0], value, __ATOMIC_RELAXED);
 212   __atomic_fetch_add (&counters[1], 1, __ATOMIC_RELAXED);
 213 }
 214 #endif
 215
 216 #ifdef L_gcov_ior_profiler
 217 /* Bitwise-OR VALUE into COUNTER.  */
 218
 219 void
 220 __gcov_ior_profiler (gcov_type *counters, gcov_type value)
 221 {
 222   *counters |= value;
 223 }
 224 #endif
 225
 226 #if defined(L_gcov_ior_profiler_atomic) && GCOV_SUPPORTS_ATOMIC
 227 /* Bitwise-OR VALUE into COUNTER.  Function is thread-safe.  */
 228
 229 void
 230 __gcov_ior_profiler_atomic (gcov_type *counters, gcov_type value)
 231 {
 232   __atomic_fetch_or (&counters[0], value, __ATOMIC_RELAXED);
 233 }
 234 #endif
 235
 236
 237 #endif /* inhibit_libc */