tildefriends/deps/libuv/src/unix/atomic-ops.h

/* Copyright (c) 2013, Ben Noordhuis <info@bnoordhuis.nl>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef UV_ATOMIC_OPS_H_
#define UV_ATOMIC_OPS_H_

#include "internal.h"  /* UV_UNUSED */

#if defined(__SUNPRO_C) || defined(__SUNPRO_CC)
#include <atomic.h>
#endif

UV_UNUSED(static int cmpxchgi(int* ptr, int oldval, int newval));
UV_UNUSED(static void cpu_relax(void));

/* Prefer hand-rolled assembly over the gcc builtins because the latter also
 * issue full memory barriers.
 */
UV_UNUSED(static int cmpxchgi(int* ptr, int oldval, int newval)) {
#if defined(__i386__) || defined(__x86_64__)
  int out;
  __asm__ __volatile__ ("lock; cmpxchg %2, %1;"
                        : "=a" (out), "+m" (*(volatile int*) ptr)
                        : "r" (newval), "0" (oldval)
                        : "memory");
  return out;
#elif defined(__MVS__)
  /* Use hand-rolled assembly because codegen from builtin __plo_CSST results in
   * a runtime bug.
   */
  __asm(" cs %0,%2,%1 \n " : "+r"(oldval), "+m"(*ptr) : "r"(newval) :);
  return oldval;
#elif defined(__SUNPRO_C) || defined(__SUNPRO_CC)
  return atomic_cas_uint((uint_t *)ptr, (uint_t)oldval, (uint_t)newval);
#else
  return __sync_val_compare_and_swap(ptr, oldval, newval);
#endif
}

UV_UNUSED(static void cpu_relax(void)) {
#if defined(__i386__) || defined(__x86_64__)
  __asm__ __volatile__ ("rep; nop" ::: "memory");  /* a.k.a. PAUSE */
#elif (defined(__arm__) && __ARM_ARCH >= 7) || defined(__aarch64__)
  __asm__ __volatile__ ("yield" ::: "memory");
#elif (defined(__ppc__) || defined(__ppc64__)) && defined(__APPLE__)
  __asm volatile ("" : : : "memory");
#elif !defined(__APPLE__) && (defined(__powerpc64__) || defined(__ppc64__) || defined(__PPC64__))
  __asm__ __volatile__ ("or 1,1,1; or 2,2,2" ::: "memory");
#endif
}

#endif  /* UV_ATOMIC_OPS_H_ */