1/* Copyright (C) 2012-2015 Free Software Foundation, Inc. 2 Contributed by Richard Henderson <rth@redhat.com>. 3 4 This file is part of the GNU Atomic Library (libatomic). 5 6 Libatomic is free software; you can redistribute it and/or modify it 7 under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 3 of the License, or 9 (at your option) any later version. 10 11 Libatomic is distributed in the hope that it will be useful, but WITHOUT ANY 12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 13 FOR A PARTICULAR PURPOSE. See the GNU General Public License for 14 more details. 15 16 Under Section 7 of GPL version 3, you are granted additional 17 permissions described in the GCC Runtime Library Exception, version 18 3.1, as published by the Free Software Foundation. 19 20 You should have received a copy of the GNU General Public License and 21 a copy of the GCC Runtime Library Exception along with this program; 22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 <http://www.gnu.org/licenses/>. */ 24 25/* Included after all more target-specific host-config.h. */ 26 27 28/* The target may have some OS specific way to implement compare-and-swap. */ 29#if !defined(atomic_compare_exchange_n) && SIZE(HAVE_ATOMIC_CAS) 30# define atomic_compare_exchange_n __atomic_compare_exchange_n 31#endif 32#if !defined(atomic_compare_exchange_w) && WSIZE(HAVE_ATOMIC_CAS) 33# define atomic_compare_exchange_w __atomic_compare_exchange_n 34#endif 35 36/* For some targets, it may be significantly faster to avoid all barriers 37 if the user only wants relaxed memory order. Sometimes we don't want 38 the extra code bloat. In all cases, use the input to avoid warnings. */ 39#if defined(WANT_SPECIALCASE_RELAXED) && !defined(__OPTIMIZE_SIZE__) 40# define maybe_specialcase_relaxed(x) ((x) == __ATOMIC_RELAXED) 41#else 42# define maybe_specialcase_relaxed(x) ((x) & 0) 43#endif 44 45/* Similar, but for targets for which the seq_cst model is sufficiently 46 more expensive than the acq_rel model. */ 47#if defined(WANT_SPECIALCASE_ACQREL) && !defined(__OPTIMIZE_SIZE__) 48# define maybe_specialcase_acqrel(x) ((x) != __ATOMIC_SEQ_CST) 49#else 50# define maybe_specialcase_acqrel(x) ((x) & 0) 51#endif 52 53 54/* The target may have some OS specific way to emit barriers. */ 55#ifndef pre_post_barrier 56static inline void __attribute__((always_inline, artificial)) 57pre_barrier(int model) 58{ 59 if (!maybe_specialcase_relaxed(model)) 60 { 61 if (maybe_specialcase_acqrel(model)) 62 __atomic_thread_fence (__ATOMIC_ACQ_REL); 63 else 64 __atomic_thread_fence (__ATOMIC_SEQ_CST); 65 } 66} 67static inline void __attribute__((always_inline, artificial)) 68post_barrier(int model) 69{ 70 pre_barrier(model); 71} 72#define pre_post_barrier 1 73#endif /* pre_post_barrier */ 74 75/* Similar, but assume that acq_rel is already handled via locks. */ 76#ifndef pre_post_seq_barrier 77static inline void __attribute__((always_inline, artificial)) 78pre_seq_barrier(int model) 79{ 80} 81static inline void __attribute__((always_inline, artificial)) 82post_seq_barrier(int model) 83{ 84} 85#define pre_post_seq_barrier 1 86#endif 87