mirror of git://gcc.gnu.org/git/gcc.git
71 lines
2.5 KiB
C
71 lines
2.5 KiB
C
/* Copyright (C) 2008 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 OpenMP Library (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 Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) 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 Lesser General Public License for
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more details.
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You should have received a copy of the GNU Lesser General Public License
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along with libgomp; see the file COPYING.LIB. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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/* As a special exception, if you link this library with other files, some
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of which are compiled with GCC, to produce an executable, this library
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does not by itself cause the resulting executable to be covered by the
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GNU General Public License. This exception does not however invalidate
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any other reasons why the executable file might be covered by the GNU
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General Public License. */
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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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#include <endian.h>
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#include <limits.h>
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#include "wait.h"
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void *
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gomp_ptrlock_get_slow (gomp_ptrlock_t *ptrlock)
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{
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int *intptr;
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__sync_bool_compare_and_swap (ptrlock, 1, 2);
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/* futex works on ints, not pointers.
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But a valid work share pointer will be at least
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8 byte aligned, so it is safe to assume the low
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32-bits of the pointer won't contain values 1 or 2. */
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__asm volatile ("" : "=r" (intptr) : "0" (ptrlock));
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#if __BYTE_ORDER == __BIG_ENDIAN
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if (sizeof (*ptrlock) > sizeof (int))
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intptr += (sizeof (*ptrlock) / sizeof (int)) - 1;
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#endif
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do
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do_wait (intptr, 2);
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while (*intptr == 2);
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__asm volatile ("" : : : "memory");
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return *ptrlock;
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}
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void
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gomp_ptrlock_set_slow (gomp_ptrlock_t *ptrlock, void *ptr)
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{
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int *intptr;
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*ptrlock = ptr;
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__asm volatile ("" : "=r" (intptr) : "0" (ptrlock));
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#if __BYTE_ORDER == __BIG_ENDIAN
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if (sizeof (*ptrlock) > sizeof (int))
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intptr += (sizeof (*ptrlock) / sizeof (int)) - 1;
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#endif
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futex_wake (intptr, INT_MAX);
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}
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