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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.  */

#ifdef __x86_64__

# ifndef SYS_futex

#  define SYS_futex     202

# endif

static inline void

futex_wait (int *addr, int val)

{

  register long r10 __asm__("%r10");

  long res;

  r10 = 0;

  __asm volatile ("syscall"

                  : "=a" (res)

                  : "0" (SYS_futex), "D" (addr), "S" (gomp_futex_wait),

                    "d" (val), "r" (r10)

                  : "r11", "rcx", "memory");

  if (__builtin_expect (res == -ENOSYS, 0))

    {

      gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;

      gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;

      r10 = 0;

      __asm volatile ("syscall"

                      : "=a" (res)

                      : "0" (SYS_futex), "D" (addr), "S" (gomp_futex_wait),

                        "d" (val), "r" (r10)

                      : "r11", "rcx", "memory");

    }

}

static inline void

futex_wake (int *addr, int count)

{

  long res;

  __asm volatile ("syscall"

                  : "=a" (res)

                  : "0" (SYS_futex), "D" (addr), "S" (gomp_futex_wake),

                    "d" (count)

                  : "r11", "rcx", "memory");

  if (__builtin_expect (res == -ENOSYS, 0))

    {

      gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;

      gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;

      __asm volatile ("syscall"

                      : "=a" (res)

                      : "0" (SYS_futex), "D" (addr), "S" (gomp_futex_wake),

                        "d" (count)

                      : "r11", "rcx", "memory");

    }

}

#else

# ifndef SYS_futex

#  define SYS_futex     240

# endif

# ifdef __PIC__

static inline long

sys_futex0 (int *addr, int op, int val)

{

  long res;

  __asm volatile ("xchgl\t%%ebx, %2\n\t"

                  "int\t$0x80\n\t"

                  "xchgl\t%%ebx, %2"

                  : "=a" (res)

                  : "0"(SYS_futex), "r" (addr), "c"(op),

                    "d"(val), "S"(0)

                  : "memory");

  return res;

}

# else

static inline long

sys_futex0 (int *addr, int op, int val)

{

  long res;

  __asm volatile ("int $0x80"

                  : "=a" (res)

                  : "0"(SYS_futex), "b" (addr), "c"(op),

                    "d"(val), "S"(0)

                  : "memory");

  return res;

}

# endif /* __PIC__ */

static inline void

futex_wait (int *addr, int val)

{

  long res = sys_futex0 (addr, gomp_futex_wait, val);

  if (__builtin_expect (res == -ENOSYS, 0))

    {

      gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;

      gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;

      sys_futex0 (addr, gomp_futex_wait, val);

    }

}

static inline void

futex_wake (int *addr, int count)

{

  long res = sys_futex0 (addr, gomp_futex_wake, count);

  if (__builtin_expect (res == -ENOSYS, 0))

    {

      gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;

      gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;

      sys_futex0 (addr, gomp_futex_wake, count);

    }

}

#endif /* __x86_64__ */

static inline void

cpu_relax (void)

{

  __asm volatile ("rep; nop" : : : "memory");

}