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-rw-r--r--libdimension/profile.c106
1 files changed, 106 insertions, 0 deletions
diff --git a/libdimension/profile.c b/libdimension/profile.c
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+++ b/libdimension/profile.c
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+/*************************************************************************
+ * Copyright (C) 2010 Tavian Barnes <tavianator@gmail.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-impl.h"
+#include <pthread.h>
+#include <stdio.h>
+#include <inttypes.h>
+
+/** Info for one predicted branch. */
+typedef struct {
+ char *location;
+ uint64_t predicted, branches;
+} dmnsn_profile_info;
+
+/** Count of mispredicted branches. */
+static dmnsn_dictionary *dmnsn_profile_data = NULL;
+/** Mutex which protects \c dmnsn_profile_data. */
+static pthread_mutex_t dmnsn_profile_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+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(DMNSN_SEVERITY_MEDIUM, "sprintf() failed.");
+ } else {
+ char key[size];
+ if (snprintf(key, size, "%s:%s:%u", file, func, line) > 0) {
+ if (pthread_mutex_lock(&dmnsn_profile_mutex) != 0) {
+ dmnsn_error(DMNSN_SEVERITY_MEDIUM, "Couldn't lock mutex.");
+ }
+
+ if (!dmnsn_profile_data) {
+ dmnsn_profile_data = dmnsn_new_dictionary(sizeof(dmnsn_profile_info));
+ }
+ dmnsn_profile_info *info = dmnsn_dictionary_at(dmnsn_profile_data, key);
+ if (info) {
+ ++info->branches;
+ if (result == expected) {
+ ++info->predicted;
+ }
+ } else {
+ dmnsn_profile_info info = {
+ .location = dmnsn_strdup(key),
+ .predicted = (result == expected) ? 1 : 0,
+ .branches = 1
+ };
+ dmnsn_dictionary_insert(dmnsn_profile_data, key, &info);
+ }
+
+ if (pthread_mutex_unlock(&dmnsn_profile_mutex) != 0) {
+ dmnsn_error(DMNSN_SEVERITY_MEDIUM, "Couldn't lock mutex.");
+ }
+ } else {
+ dmnsn_error(DMNSN_SEVERITY_MEDIUM, "sprintf() failed.");
+ }
+ }
+
+ return result;
+}
+
+static void
+dmnsn_print_bad_prediction(void *ptr)
+{
+ dmnsn_profile_info *info = ptr;
+ double rate = ((double)info->predicted)/info->branches;
+ if (rate < 0.75 || info->branches < 100000) {
+ fprintf(stderr,
+ "Bad branch prediction: %s: %" PRIu64 "/%" PRIu64 "\n",
+ info->location, info->predicted, info->branches);
+ }
+
+ dmnsn_free(info->location);
+}
+
+static void __attribute__((destructor))
+dmnsn_print_bad_predictions(void)
+{
+ if (dmnsn_profile_data) {
+ dmnsn_dictionary_apply(dmnsn_profile_data, &dmnsn_print_bad_prediction);
+ dmnsn_delete_dictionary(dmnsn_profile_data);
+ }
+}