doacross.h revision 1.6 
1/* Copyright (C) 2015-2020 Free Software Foundation, Inc.
2   Contributed by Jakub Jelinek <jakub@redhat.com>.
3
4   This file is part of the GNU Offloading and Multi Processing Library
5   (libgomp).
6
7   Libgomp is free software; you can redistribute it and/or modify it
8   under the terms of the GNU General Public License as published by
9   the Free Software Foundation; either version 3, or (at your option)
10   any later version.
11
12   Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
13   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
14   FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
15   more details.
16
17   Under Section 7 of GPL version 3, you are granted additional
18   permissions described in the GCC Runtime Library Exception, version
19   3.1, as published by the Free Software Foundation.
20
21   You should have received a copy of the GNU General Public License and
22   a copy of the GCC Runtime Library Exception along with this program;
23   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
24   <http://www.gnu.org/licenses/>.  */
25
26/* This is a generic implementation of doacross spinning.  */
27
28#ifndef GOMP_DOACROSS_H
29#define GOMP_DOACROSS_H 1
30
31#include "libgomp.h"
32#include <errno.h>
33
34#ifdef HAVE_ATTRIBUTE_VISIBILITY
35# pragma GCC visibility push(hidden)
36#endif
37
38static inline void
39cpu_relax (void)
40{
41  __asm volatile ("" : : : "memory");
42}
43
44static inline void doacross_spin (unsigned long *addr, unsigned long expected,
45				  unsigned long cur)
46{
47  /* FIXME: back off depending on how large expected - cur is.  */
48  do
49    {
50      cpu_relax ();
51      cur = __atomic_load_n (addr, MEMMODEL_RELAXED);
52      if (expected < cur)
53	return;
54    }
55  while (1);
56}
57
58#ifdef HAVE_ATTRIBUTE_VISIBILITY
59# pragma GCC visibility pop
60#endif
61
62#endif /* GOMP_DOACROSS_H */
63