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/* Copyright (C) 2005-2022 Free Software Foundation, Inc.
Contributed by Richard Henderson <>.
This file is part of the GNU Offloading and Multi Processing Library
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
<>. */
/* This is a Linux specific implementation of a mutex synchronization
mechanism for libgomp. This type is private to the library. This
implementation uses atomic instructions and the futex syscall. */
#ifndef GOMP_MUTEX_H
#define GOMP_MUTEX_H 1
typedef int gomp_mutex_t;
#define GOMP_MUTEX_INIT_0 1
extern void gomp_mutex_lock_slow (gomp_mutex_t *mutex, int);
extern void gomp_mutex_unlock_slow (gomp_mutex_t *mutex);
static inline void
gomp_mutex_init (gomp_mutex_t *mutex)
*mutex = 0;
static inline void
gomp_mutex_destroy (gomp_mutex_t *mutex)
static inline void
gomp_mutex_lock (gomp_mutex_t *mutex)
int oldval = 0;
if (!__atomic_compare_exchange_n (mutex, &oldval, 1, false,
gomp_mutex_lock_slow (mutex, oldval);
static inline void
gomp_mutex_unlock (gomp_mutex_t *mutex)
int wait = __atomic_exchange_n (mutex, 0, MEMMODEL_RELEASE);
if (__builtin_expect (wait < 0, 0))
gomp_mutex_unlock_slow (mutex);
#endif /* GOMP_MUTEX_H */