75 lines
2.3 KiB
C
75 lines
2.3 KiB
C
/* Copyright (C) 2008-2020 Free Software Foundation, Inc.
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Contributed by Jakub Jelinek <jakub@redhat.com>.
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This file is part of the GNU Offloading and Multi Processing Library
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(libgomp).
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Libgomp is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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/* This is a Linux specific implementation of a mutex synchronization
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mechanism for libgomp. This type is private to the library. This
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implementation uses atomic instructions and the futex syscall. */
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#ifndef GOMP_WAIT_H
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#define GOMP_WAIT_H 1
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#include "libgomp.h"
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#include <errno.h>
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#define FUTEX_WAIT 0
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#define FUTEX_WAKE 1
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#define FUTEX_PRIVATE_FLAG 128
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#ifdef HAVE_ATTRIBUTE_VISIBILITY
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# pragma GCC visibility push(hidden)
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#endif
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extern int gomp_futex_wait, gomp_futex_wake;
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#include <futex.h>
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static inline int do_spin (int *addr, int val)
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{
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unsigned long long i, count = gomp_spin_count_var;
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if (__builtin_expect (__atomic_load_n (&gomp_managed_threads,
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MEMMODEL_RELAXED)
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> gomp_available_cpus, 0))
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count = gomp_throttled_spin_count_var;
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for (i = 0; i < count; i++)
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if (__builtin_expect (__atomic_load_n (addr, MEMMODEL_RELAXED) != val, 0))
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return 0;
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else
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cpu_relax ();
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return 1;
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}
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static inline void do_wait (int *addr, int val)
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{
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if (do_spin (addr, val))
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futex_wait (addr, val);
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}
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#ifdef HAVE_ATTRIBUTE_VISIBILITY
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# pragma GCC visibility pop
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#endif
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#endif /* GOMP_WAIT_H */
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