1 /* Copyright (c) 2013, Ben Noordhuis <info@bnoordhuis.nl>
3 * Permission to use, copy, modify, and/or distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
10 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
12 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
13 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 #ifndef UV_ATOMIC_OPS_H_
17 #define UV_ATOMIC_OPS_H_
19 #include "internal.h" /* UV_UNUSED */
21 #if defined(__SUNPRO_C) || defined(__SUNPRO_CC)
25 UV_UNUSED(static int cmpxchgi(int* ptr, int oldval, int newval));
26 UV_UNUSED(static void cpu_relax(void));
28 /* Prefer hand-rolled assembly over the gcc builtins because the latter also
29 * issue full memory barriers.
31 UV_UNUSED(static int cmpxchgi(int* ptr, int oldval, int newval)) {
32 #if defined(__i386__) || defined(__x86_64__)
34 __asm__ __volatile__ ("lock; cmpxchg %2, %1;"
35 : "=a" (out), "+m" (*(volatile int*) ptr)
36 : "r" (newval), "0" (oldval)
39 #elif defined(_AIX) && defined(__ibmxl__)
40 /* FIXME: This is not actually atomic but XLClang 16.1 for AIX
41 does not provide __sync_val_compare_and_swap or an equivalent.
42 Its documentation suggests using C++11 atomics but this is C. */
43 __compare_and_swap((volatile int*)ptr, &oldval, newval);
45 #elif defined(__MVS__)
47 if (__plo_CSST(ptr, (unsigned int*) &oldval, newval,
48 (unsigned int*) ptr, *ptr, &op4))
52 #elif defined(__SUNPRO_C) || defined(__SUNPRO_CC)
53 return atomic_cas_uint((uint_t *)ptr, (uint_t)oldval, (uint_t)newval);
55 return __sync_val_compare_and_swap(ptr, oldval, newval);
59 UV_UNUSED(static void cpu_relax(void)) {
60 #if defined(__i386__) || defined(__x86_64__)
61 __asm__ __volatile__ ("rep; nop" ::: "memory"); /* a.k.a. PAUSE */
62 #elif (defined(__arm__) && __ARM_ARCH >= 7) || defined(__aarch64__)
63 __asm__ __volatile__ ("yield" ::: "memory");
64 #elif defined(__powerpc64__) || defined(__ppc64__) || defined(__PPC64__)
65 __asm__ __volatile__ ("or 1,1,1; or 2,2,2" ::: "memory");
69 #endif /* UV_ATOMIC_OPS_H_ */