4.9.x/gcov-src/libgcov-profiler.c

/* Routines required for instrumenting a program.  */
/* Compile this one with gcc.  */
/* Copyright (C) 1989-2014 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.

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/>.  */

#include "libgcov.h"
#if !defined(inhibit_libc)

#ifdef L_gcov_interval_profiler
/* If VALUE is in interval <START, START + STEPS - 1>, then increases the
   corresponding counter in COUNTERS.  If the VALUE is above or below
   the interval, COUNTERS[STEPS] or COUNTERS[STEPS + 1] is increased
   instead.  */

void
__gcov_interval_profiler (gcov_type *counters, gcov_type value,
                          int start, unsigned steps)
{
  gcov_type delta = value - start;
  if (delta < 0)
    counters[steps + 1]++;
  else if (delta >= steps)
    counters[steps]++;
  else
    counters[delta]++;
}
#endif

#ifdef L_gcov_pow2_profiler
/* If VALUE is a power of two, COUNTERS[1] is incremented.  Otherwise
   COUNTERS[0] is incremented.  */

void
__gcov_pow2_profiler (gcov_type *counters, gcov_type value)
{
  if (value & (value - 1))
    counters[0]++;
  else
    counters[1]++;
}
#endif

/* Tries to determine the most common value among its inputs.  Checks if the
   value stored in COUNTERS[0] matches VALUE.  If this is the case, COUNTERS[1]
   is incremented.  If this is not the case and COUNTERS[1] is not zero,
   COUNTERS[1] is decremented.  Otherwise COUNTERS[1] is set to one and
   VALUE is stored to COUNTERS[0].  This algorithm guarantees that if this
   function is called more than 50% of the time with one value, this value
   will be in COUNTERS[0] in the end.

   In any case, COUNTERS[2] is incremented.  */

static inline void
__gcov_one_value_profiler_body (gcov_type *counters, gcov_type value)
{
  if (value == counters[0])
    counters[1]++;
  else if (counters[1] == 0)
    {
      counters[1] = 1;
      counters[0] = value;
    }
  else
    counters[1]--;
  counters[2]++;
}

/* Atomic update version of __gcov_one_value_profile_body().  */
static inline void
__gcov_one_value_profiler_body_atomic (gcov_type *counters, gcov_type value)
{
  if (value == counters[0])
    GCOV_TYPE_ATOMIC_FETCH_ADD_FN (&counters[1], 1, MEMMODEL_RELAXED);
  else if (counters[1] == 0)
    {
      counters[1] = 1;
      counters[0] = value;
    }
  else
    GCOV_TYPE_ATOMIC_FETCH_ADD_FN (&counters[1], -1, MEMMODEL_RELAXED);
  GCOV_TYPE_ATOMIC_FETCH_ADD_FN (&counters[2], 1, MEMMODEL_RELAXED);
}


#ifdef L_gcov_one_value_profiler
void
__gcov_one_value_profiler (gcov_type *counters, gcov_type value)
{
  __gcov_one_value_profiler_body (counters, value);
}

void
__gcov_one_value_profiler_atomic (gcov_type *counters, gcov_type value)
{
  __gcov_one_value_profiler_body_atomic (counters, value);
}


#endif

#ifdef L_gcov_indirect_call_profiler
/* This function exist only for workaround of binutils bug 14342.
   Once this compatibility hack is obsolette, it can be removed.  */

/* By default, the C++ compiler will use function addresses in the
   vtable entries.  Setting TARGET_VTABLE_USES_DESCRIPTORS to nonzero
   tells the compiler to use function descriptors instead.  The value
   of this macro says how many words wide the descriptor is (normally 2),
   but it may be dependent on target flags.  Since we do not have access
   to the target flags here we just check to see if it is set and use
   that to set VTABLE_USES_DESCRIPTORS to 0 or 1.

   It is assumed that the address of a function descriptor may be treated
   as a pointer to a function.  */

#ifdef TARGET_VTABLE_USES_DESCRIPTORS
#define VTABLE_USES_DESCRIPTORS 1
#else
#define VTABLE_USES_DESCRIPTORS 0
#endif

/* Tries to determine the most common value among its inputs. */
void
__gcov_indirect_call_profiler (gcov_type* counter, gcov_type value,
                               void* cur_func, void* callee_func)
{
  /* If the C++ virtual tables contain function descriptors then one
     function may have multiple descriptors and we need to dereference
     the descriptors to see if they point to the same function.  */
  if (cur_func == callee_func
      || (VTABLE_USES_DESCRIPTORS && callee_func
          && *(void **) cur_func == *(void **) callee_func))
    __gcov_one_value_profiler_body (counter, value);
}


/* Atomic update version of __gcov_indirect_call_profiler().  */
void
__gcov_indirect_call_profiler_atomic (gcov_type* counter, gcov_type value,
                                      void* cur_func, void* callee_func)
{
  if (cur_func == callee_func
      || (VTABLE_USES_DESCRIPTORS && callee_func
          && *(void **) cur_func == *(void **) callee_func))
    __gcov_one_value_profiler_body_atomic (counter, value);
}


#endif
#ifdef L_gcov_indirect_call_profiler_v2

/* These two variables are used to actually track caller and callee.  Keep
   them in TLS memory so races are not common (they are written to often).
   The variables are set directly by GCC instrumented code, so declaration
   here must match one in tree-profile.c  */

#if defined(HAVE_CC_TLS) && !defined (USE_EMUTLS)
__thread
#endif
void * __gcov_indirect_call_callee;
#if defined(HAVE_CC_TLS) && !defined (USE_EMUTLS)
__thread
#endif
gcov_type * __gcov_indirect_call_counters;

/* By default, the C++ compiler will use function addresses in the
   vtable entries.  Setting TARGET_VTABLE_USES_DESCRIPTORS to nonzero
   tells the compiler to use function descriptors instead.  The value
   of this macro says how many words wide the descriptor is (normally 2),
   but it may be dependent on target flags.  Since we do not have access
   to the target flags here we just check to see if it is set and use
   that to set VTABLE_USES_DESCRIPTORS to 0 or 1.

   It is assumed that the address of a function descriptor may be treated
   as a pointer to a function.  */

#ifdef TARGET_VTABLE_USES_DESCRIPTORS
#define VTABLE_USES_DESCRIPTORS 1
#else
#define VTABLE_USES_DESCRIPTORS 0
#endif

/* Tries to determine the most common value among its inputs. */
void
__gcov_indirect_call_profiler_v2 (gcov_type value, void* cur_func)
{
  /* If the C++ virtual tables contain function descriptors then one
     function may have multiple descriptors and we need to dereference
     the descriptors to see if they point to the same function.  */
  if (cur_func == __gcov_indirect_call_callee
      || (VTABLE_USES_DESCRIPTORS && __gcov_indirect_call_callee
          && *(void **) cur_func == *(void **) __gcov_indirect_call_callee))
    __gcov_one_value_profiler_body (__gcov_indirect_call_counters, value);
}

void
__gcov_indirect_call_profiler_atomic_v2 (gcov_type value, void* cur_func)
{
  /* If the C++ virtual tables contain function descriptors then one
     function may have multiple descriptors and we need to dereference
     the descriptors to see if they point to the same function.  */
  if (cur_func == __gcov_indirect_call_callee
      || (VTABLE_USES_DESCRIPTORS && __gcov_indirect_call_callee
          && *(void **) cur_func == *(void **) __gcov_indirect_call_callee))
    __gcov_one_value_profiler_body_atomic (__gcov_indirect_call_counters, value);
}

#endif

/*
#if defined(L_gcov_direct_call_profiler) || defined(L_gcov_indirect_call_topn_profiler)
__attribute__ ((weak)) gcov_unsigned_t __gcov_lipo_sampling_period;
#endif
*/

extern gcov_unsigned_t __gcov_lipo_sampling_period;

#ifdef L_gcov_indirect_call_topn_profiler

#include "gthr.h"

#ifdef __GTHREAD_MUTEX_INIT
__thread int in_profiler;
ATTRIBUTE_HIDDEN __gthread_mutex_t __indir_topn_val_mx = __GTHREAD_MUTEX_INIT;
#endif

/* Tries to keep track the most frequent N values in the counters where
   N is specified by parameter TOPN_VAL. To track top N values, 2*N counter
   entries are used.
   counter[0] --- the accumative count of the number of times one entry in
                  in the counters gets evicted/replaced due to limited capacity.
                  When this value reaches a threshold, the bottom N values are
                  cleared.
   counter[1] through counter[2*N] records the top 2*N values collected so far.
   Each value is represented by two entries: count[2*i+1] is the ith value, and
   count[2*i+2] is the number of times the value is seen.  */

static void
__gcov_topn_value_profiler_body (gcov_type *counters, gcov_type value,
                                 gcov_unsigned_t topn_val)
{
   unsigned i, found = 0, have_zero_count = 0;

   gcov_type *entry;
   gcov_type *lfu_entry = &counters[1];
   gcov_type *value_array = &counters[1];
   gcov_type *num_eviction = &counters[0];

   /* There are 2*topn_val values tracked, each value takes two slots in the
      counter array */
#ifdef __GTHREAD_MUTEX_INIT
   /* If this is reentry, return.  */
   if (in_profiler == 1)
     return;

   in_profiler = 1;
   __gthread_mutex_lock (&__indir_topn_val_mx);
#endif
   for (i = 0; i < topn_val << 2; i += 2)
     {
       entry = &value_array[i];
       if (entry[0] == value)
         {
           entry[1]++ ;
           found = 1;
           break;
         }
       else if (entry[1] == 0)
         {
           lfu_entry = entry;
           have_zero_count = 1;
         }
      else if (entry[1] < lfu_entry[1])
        lfu_entry = entry;
     }

   if (found)
     {
       in_profiler = 0;
#ifdef __GTHREAD_MUTEX_INIT
       __gthread_mutex_unlock (&__indir_topn_val_mx);
#endif
       return;
     }

   /* lfu_entry is either an empty entry or an entry
      with lowest count, which will be evicted.  */
   lfu_entry[0] = value;
   lfu_entry[1] = 1;

#define GCOV_ICALL_COUNTER_CLEAR_THRESHOLD 3000

   /* Too many evictions -- time to clear bottom entries to
      avoid hot values bumping each other out.  */
   if (!have_zero_count
       && ++*num_eviction >= GCOV_ICALL_COUNTER_CLEAR_THRESHOLD)
     {
       unsigned i, j;
       gcov_type **p;
       gcov_type **tmp_cnts
         = (gcov_type **)alloca (topn_val * sizeof(gcov_type *));

       *num_eviction = 0;

       /* Find the largest topn_val values from the group of
          2*topn_val values and put the addresses into tmp_cnts.  */
       for (i = 0; i < topn_val; i++)
         tmp_cnts[i] = &value_array[i * 2 + 1];

       for (i = topn_val * 2; i < topn_val << 2; i += 2)
         {
           p = &tmp_cnts[0];
           for (j = 1; j < topn_val; j++)
             if (*tmp_cnts[j] > **p)
               p = &tmp_cnts[j];
           if (value_array[i + 1] < **p)
             *p = &value_array[i + 1];
         }

       /* Zero out low value entries.  */
       for (i = 0; i < topn_val; i++)
         {
           *tmp_cnts[i] = 0;
           *(tmp_cnts[i] - 1) = 0;
         }
     }

#ifdef __GTHREAD_MUTEX_INIT
     in_profiler = 0;
     __gthread_mutex_unlock (&__indir_topn_val_mx);
#endif
}

#if defined(HAVE_CC_TLS) && !defined (USE_EMUTLS)
__thread
#endif
gcov_type *__gcov_indirect_call_topn_counters ATTRIBUTE_HIDDEN;

#if defined(HAVE_CC_TLS) && !defined (USE_EMUTLS)
__thread
#endif
void *__gcov_indirect_call_topn_callee ATTRIBUTE_HIDDEN;

#if defined(HAVE_CC_TLS) && !defined (USE_EMUTLS)
__thread
#endif
gcov_unsigned_t __gcov_indirect_call_sampling_counter ATTRIBUTE_HIDDEN;

#ifdef TARGET_VTABLE_USES_DESCRIPTORS
#define VTABLE_USES_DESCRIPTORS 1
#else
#define VTABLE_USES_DESCRIPTORS 0
#endif
void
__gcov_indirect_call_topn_profiler (void *cur_func,
                                    void *cur_module_gcov_info,
                                    gcov_unsigned_t cur_func_id)
{
  void *callee_func = __gcov_indirect_call_topn_callee;
  gcov_type *counter = __gcov_indirect_call_topn_counters;
  /* If the C++ virtual tables contain function descriptors then one
     function may have multiple descriptors and we need to dereference
     the descriptors to see if they point to the same function.  */
  if (cur_func == callee_func
      || (VTABLE_USES_DESCRIPTORS && callee_func
         && *(void **) cur_func == *(void **) callee_func))
    {
      if (++__gcov_indirect_call_sampling_counter >= __gcov_lipo_sampling_period)
        {
          __gcov_indirect_call_sampling_counter = 0;
          gcov_type global_id
              = ((struct gcov_info *) cur_module_gcov_info)->mod_info->ident;
          global_id = GEN_FUNC_GLOBAL_ID (global_id, cur_func_id);
          __gcov_topn_value_profiler_body (counter, global_id, GCOV_ICALL_TOPN_VAL);
        }
      __gcov_indirect_call_topn_callee = 0;
    }
}

#endif

#ifdef L_gcov_direct_call_profiler
#if defined(HAVE_CC_TLS) && !defined (USE_EMUTLS)
__thread
#endif
gcov_type *__gcov_direct_call_counters ATTRIBUTE_HIDDEN;
#if defined(HAVE_CC_TLS) && !defined (USE_EMUTLS)
__thread
#endif
void *__gcov_direct_call_callee ATTRIBUTE_HIDDEN;
#if defined(HAVE_CC_TLS) && !defined (USE_EMUTLS)
__thread
#endif
gcov_unsigned_t __gcov_direct_call_sampling_counter ATTRIBUTE_HIDDEN;

/* Direct call profiler. */

void
__gcov_direct_call_profiler (void *cur_func,
           void *cur_module_gcov_info,
           gcov_unsigned_t cur_func_id)
{
  if (cur_func == __gcov_direct_call_callee)
    {
      if (++__gcov_direct_call_sampling_counter >= __gcov_lipo_sampling_period)
        {
          __gcov_direct_call_sampling_counter = 0;
          gcov_type global_id
              = ((struct gcov_info *) cur_module_gcov_info)->mod_info->ident;
          global_id = GEN_FUNC_GLOBAL_ID (global_id, cur_func_id);
          __gcov_direct_call_counters[0] = global_id;
          __gcov_direct_call_counters[1]++;
        }
      __gcov_direct_call_callee = 0;
    }
}
#endif


#ifdef L_gcov_time_profiler

/* Counter for first visit of each function.  */
static gcov_type function_counter;

/* Sets corresponding COUNTERS if there is no value.  */

void
__gcov_time_profiler (gcov_type* counters)
{
  if (!counters[0])
    counters[0] = ++function_counter;
}
#endif

#ifdef L_gcov_average_profiler
/* Increase corresponding COUNTER by VALUE.  FIXME: Perhaps we want
   to saturate up.  */

void
__gcov_average_profiler (gcov_type *counters, gcov_type value)
{
  counters[0] += value;
  counters[1] ++;
}
#endif

#ifdef L_gcov_ior_profiler
/* Bitwise-OR VALUE into COUNTER.  */

void
__gcov_ior_profiler (gcov_type *counters, gcov_type value)
{
  *counters |= value;
}
#endif

#endif /* inhibit_libc */