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/*************************************************************************
* Copyright (C) 2010-2011 Tavian Barnes <tavianator@tavianator.com> *
* *
* This file is part of The Dimension Library. *
* *
* The Dimension Library is free software; you can redistribute it and/ *
* or modify it under the terms of the GNU Lesser General Public License *
* as published by the Free Software Foundation; either version 3 of the *
* License, or (at your option) any later version. *
* *
* The Dimension Library 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 *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this program. If not, see *
* <http://www.gnu.org/licenses/>. *
*************************************************************************/
/**
* @file
* Branch profile accounting.
*/
#include "dimension-internal.h"
#include <pthread.h>
#include <stdio.h>
#include <inttypes.h>
/// Information on one predicted branch.
typedef struct {
char *location;
uint64_t predicted, branches;
} dmnsn_branch;
/// Count of mispredicted branches.
static dmnsn_dictionary *dmnsn_profile = NULL;
/// Mutex which protects \c dmnsn_profile.
static pthread_mutex_t dmnsn_profile_mutex = PTHREAD_MUTEX_INITIALIZER;
/// Thread-local count of mispredicted branches.
static pthread_key_t dmnsn_thread_profile;
/// Initialize the thread-specific pointer exactly once.
static pthread_once_t dmnsn_thread_profile_once = PTHREAD_ONCE_INIT;
/// Add thread-specific profile data to the global counts.
static void
dmnsn_profile_globalize(void *ptr)
{
dmnsn_branch *branch = ptr;
dmnsn_branch *global = dmnsn_dictionary_at(dmnsn_profile, branch->location);
if (global) {
global->predicted += branch->predicted;
global->branches += branch->branches;
dmnsn_free(branch->location);
} else {
dmnsn_dictionary_insert(dmnsn_profile, branch->location, branch);
}
}
/// Destructor function for thread-specific profile data.
static void
dmnsn_delete_thread_profile(void *ptr)
{
dmnsn_dictionary *thread_profile = ptr;
dmnsn_lock_mutex(&dmnsn_profile_mutex);
dmnsn_dictionary_apply(thread_profile, dmnsn_profile_globalize);
dmnsn_unlock_mutex(&dmnsn_profile_mutex);
dmnsn_delete_dictionary(thread_profile);
}
/// Initialize the thread-specific pointer.
static void
dmnsn_initialize_thread_profile(void)
{
dmnsn_key_create(&dmnsn_thread_profile, dmnsn_delete_thread_profile);
dmnsn_lock_mutex(&dmnsn_profile_mutex);
dmnsn_profile = dmnsn_new_dictionary(sizeof(dmnsn_branch));
dmnsn_unlock_mutex(&dmnsn_profile_mutex);
}
/// Get the thread-specific profile data.
static dmnsn_dictionary *
dmnsn_get_thread_profile(void)
{
dmnsn_once(&dmnsn_thread_profile_once, dmnsn_initialize_thread_profile);
return pthread_getspecific(dmnsn_thread_profile);
}
/// Set the thread-specific profile data.
static void
dmnsn_set_thread_profile(dmnsn_dictionary *thread_profile)
{
dmnsn_setspecific(dmnsn_thread_profile, thread_profile);
}
bool
dmnsn_expect(bool result, bool expected, const char *func, const char *file,
unsigned int line)
{
int size = snprintf(NULL, 0, "%s:%s:%u", file, func, line) + 1;
if (size < 1) {
dmnsn_error("sprintf() failed.");
}
char key[size];
if (snprintf(key, size, "%s:%s:%u", file, func, line) < 0) {
dmnsn_error("sprintf() failed.");
}
dmnsn_dictionary *thread_profile = dmnsn_get_thread_profile();
if (!thread_profile) {
thread_profile = dmnsn_new_dictionary(sizeof(dmnsn_branch));
dmnsn_set_thread_profile(thread_profile);
}
dmnsn_branch *branch = dmnsn_dictionary_at(thread_profile, key);
if (branch) {
++branch->branches;
if (result == expected) {
++branch->predicted;
}
} else {
dmnsn_branch new_branch = {
.location = dmnsn_strdup(key),
.predicted = (result == expected) ? 1 : 0,
.branches = 1
};
dmnsn_dictionary_insert(thread_profile, key, &new_branch);
}
return result;
}
static void
dmnsn_print_bad_prediction(void *ptr)
{
dmnsn_branch *branch = ptr;
double rate = ((double)branch->predicted)/branch->branches;
if (rate < 0.75 || branch->branches < 100000) {
fprintf(stderr,
"Bad branch prediction: %s: %" PRIu64 "/%" PRIu64 " (%g%%)\n",
branch->location, branch->predicted, branch->branches, 100.0*rate);
}
dmnsn_free(branch->location);
}
DMNSN_DESTRUCTOR static void
dmnsn_print_bad_predictions(void)
{
dmnsn_dictionary *thread_profile = dmnsn_get_thread_profile();
if (thread_profile) {
dmnsn_delete_thread_profile(thread_profile);
dmnsn_set_thread_profile(NULL);
}
dmnsn_lock_mutex(&dmnsn_profile_mutex);
dmnsn_dictionary_apply(dmnsn_profile, dmnsn_print_bad_prediction);
dmnsn_delete_dictionary(dmnsn_profile);
dmnsn_profile = NULL;
dmnsn_unlock_mutex(&dmnsn_profile_mutex);
}
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