1  /* Copyright (C) 2015-2023 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  
      38  static inline void
      39  cpu_relax (void)
      40  {
      41    __asm volatile ("" : : : "memory");
      42  }
      43  
      44  static 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 */