Create new helper compiler_barrier to prevent compiler from over-optimizing bench.

bench/common.c

@@ -0,0 +1,32 @@
+/*
+ * M*LIB - common functions for bench module
+ *
+ * Copyright (c) 2017-2019, Patrick Pelissier
+ * All rights reserved.
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * + Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * + Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include "common.h"
+
+void compiler_barrier(void *p)
+{
+  // Do nothing, but let the compiler thinks that we did.
+  (void) p;
+}

bench/common.h

@@ -25,11 +25,14 @@
 #ifndef __COMMON_BENCH__H
 #define __COMMON_BENCH__H
 
+#include <stdio.h>
+#include <stdlib.h>
+
 #if defined(_WIN32)
 /* WINDOWS variant */
 #include <windows.h>
 
-static unsigned long long
+static inline unsigned long long
 cputime (void)
 {
 	LARGE_INTEGER freq, val;
@@ -44,7 +47,7 @@ cputime (void)
 #include <sys/resource.h>
 #include <sys/time.h>
 
-static unsigned long long
+static inline unsigned long long
 cputime (void)
 {
 #if defined(MULTI_THREAD_MEASURE)
@@ -62,23 +65,24 @@ cputime (void)
 
 #endif
 
-unsigned long g_result;
+static unsigned long g_result;
 #if defined(MULTI_THREAD_MEASURE)
 M_THREAD_ATTR
 #endif
-unsigned int randValue = 0;
+static unsigned int randValue = 0;
 
-static void rand_init(void)
+static inline void rand_init(void)
 {
   randValue = 0;
 }
-static unsigned int rand_get(void)
+
+static inline unsigned int rand_get(void)
 {
   randValue = randValue * 31421U + 6927U;
   return randValue;
 }
 
-static void test_function(const char str[], size_t n, void (*func)(size_t))
+static inline void test_function(const char str[], size_t n, void (*func)(size_t))
 {
   unsigned long long start, end;
   rand_init();
@@ -123,4 +127,9 @@ static inline int get_cpu_count(void)
 #endif
 }
 
+#ifdef __cplusplus
+extern "C"
+#endif
+void compiler_barrier(void *p);
+
 #endif