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- /* Copyright (C) 2008-2022 Free Software Foundation, Inc.
- Contributed by Jakub Jelinek <jakub@redhat.com>.
- This file is part of the GNU Offloading and Multi Processing 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/>. */
- /* 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_WAIT_H
- #define GOMP_WAIT_H 1
- #include "libgomp.h"
- #include <errno.h>
- #define FUTEX_WAIT 0
- #define FUTEX_WAKE 1
- #define FUTEX_PRIVATE_FLAG 128
- #ifdef HAVE_ATTRIBUTE_VISIBILITY
- # pragma GCC visibility push(hidden)
- #endif
- extern int gomp_futex_wait, gomp_futex_wake;
- #include <futex.h>
- static inline int do_spin (int *addr, int val)
- {
- unsigned long long i, count = gomp_spin_count_var;
- if (__builtin_expect (__atomic_load_n (&gomp_managed_threads,
- MEMMODEL_RELAXED)
- > gomp_available_cpus, 0))
- count = gomp_throttled_spin_count_var;
- for (i = 0; i < count; i++)
- if (__builtin_expect (__atomic_load_n (addr, MEMMODEL_RELAXED) != val, 0))
- return 0;
- else
- cpu_relax ();
- return 1;
- }
- static inline void do_wait (int *addr, int val)
- {
- if (do_spin (addr, val))
- futex_wait (addr, val);
- }
- #ifdef HAVE_ATTRIBUTE_VISIBILITY
- # pragma GCC visibility pop
- #endif
- #endif /* GOMP_WAIT_H */
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