config/linux/alpha/futex.h

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/* Copyright (C) 2005, 2008, 2009 Free Software Foundation, Inc.
   Contributed by Richard Henderson <rth@redhat.com>.

   This file is part of the GNU OpenMP Library (libgomp).

   Libgomp is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3, or (at your option)
   any later version.

   Libgomp 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 General Public License for
   more details.

   Under Section 7 of GPL version 3, you are granted additional
   permissions described in the GCC Runtime Library Exception, version
   3.1, as published by the Free Software Foundation.

   You should have received a copy of the GNU General Public License and
   a copy of the GCC Runtime Library Exception along with this program;
   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
   <http://www.gnu.org/licenses/>.  */

/* Provide target-specific access to the futex system call.  */

#ifndef SYS_futex
#define SYS_futex               394
#endif


static inline void
futex_wait (int *addr, int val)
{
  register long sc_0 __asm__("$0");
  register long sc_16 __asm__("$16");
  register long sc_17 __asm__("$17");
  register long sc_18 __asm__("$18");
  register long sc_19 __asm__("$19");

  sc_0 = SYS_futex;
  sc_16 = (long) addr;
  sc_17 = gomp_futex_wait;
  sc_18 = val;
  sc_19 = 0;
  __asm volatile ("callsys"
          : "=r" (sc_0), "=r"(sc_19)
          : "0"(sc_0), "r" (sc_16), "r"(sc_17), "r"(sc_18), "1"(sc_19)
          : "$1", "$2", "$3", "$4", "$5", "$6", "$7", "$8",
            "$22", "$23", "$24", "$25", "$27", "$28", "memory");
  if (__builtin_expect (sc_19, 0) && sc_0 == ENOSYS)
    {
      gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
      gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
      sc_0 = SYS_futex;
      sc_17 &= ~FUTEX_PRIVATE_FLAG;
      sc_19 = 0;
      __asm volatile ("callsys"
              : "=r" (sc_0), "=r"(sc_19)
              : "0"(sc_0), "r" (sc_16), "r"(sc_17), "r"(sc_18),
            "1"(sc_19)
              : "$1", "$2", "$3", "$4", "$5", "$6", "$7", "$8",
            "$22", "$23", "$24", "$25", "$27", "$28", "memory");
    }
}

static inline void
futex_wake (int *addr, int count)
{
  register long sc_0 __asm__("$0");
  register long sc_16 __asm__("$16");
  register long sc_17 __asm__("$17");
  register long sc_18 __asm__("$18");
  register long sc_19 __asm__("$19");

  sc_0 = SYS_futex;
  sc_16 = (long) addr;
  sc_17 = gomp_futex_wake;
  sc_18 = count;
  __asm volatile ("callsys"
          : "=r" (sc_0), "=r"(sc_19)
          : "0"(sc_0), "r" (sc_16), "r"(sc_17), "r"(sc_18)
          : "$1", "$2", "$3", "$4", "$5", "$6", "$7", "$8",
            "$22", "$23", "$24", "$25", "$27", "$28", "memory");
  if (__builtin_expect (sc_19, 0) && sc_0 == ENOSYS)
    {
      gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
      gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
      sc_0 = SYS_futex;
      sc_17 &= ~FUTEX_PRIVATE_FLAG;
      __asm volatile ("callsys"
              : "=r" (sc_0), "=r"(sc_19)
              : "0"(sc_0), "r" (sc_16), "r"(sc_17), "r"(sc_18)
              : "$1", "$2", "$3", "$4", "$5", "$6", "$7", "$8",
            "$22", "$23", "$24", "$25", "$27", "$28", "memory");
    }
}

static inline void
cpu_relax (void)
{
  __asm volatile ("" : : : "memory");
}

static inline void
atomic_write_barrier (void)
{
  __asm volatile ("wmb" : : : "memory");
}

---