1 /* Copyright (C) 2015-2018 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 */ 63