libgcc/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 "tconfig.h"
#include "tsystem.h"
#include "coretypes.h"
#include "tm.h"
#include "libgcc_tm.h"

#if !defined(inhibit_libc)
#define IN_LIBGCOV 1
#include "gcov-io.h"

#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]++;
}

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

#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);
}
#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 */