1 /*
2 * This file is part of ltrace.
3 * Copyright (C) 2012 Petr Machata, Red Hat Inc.
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License as
7 * published by the Free Software Foundation; either version 2 of the
8 * License, or (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
18 * 02110-1301 USA
19 */
20
21 #include <stdint.h>
22
23 __attribute__((noinline, optimize(3))) void
atomic_add(uint32_t * a,uint32_t b)24 atomic_add(uint32_t *a, uint32_t b)
25 {
26 __asm__ volatile("lwarx 9,0,%0\n"
27 "add 9,9,%2\n"
28 "stwcx. 9,0,%0\n"
29 "bne- atomic_add\n"
30 : "=r"(a)
31 : "0"(a), "r"(b)
32 : "%r9");
33 }
34
35 uint32_t a = 0;
36
37 __attribute__((optimize(0))) int
main(int argc,char ** argv)38 main(int argc, char **argv)
39 {
40 atomic_add(&a, 5);
41 atomic_add(&a, 10);
42 atomic_add(&a, 15);
43 return a;
44 }
45