118 lines
3.4 KiB
C++
118 lines
3.4 KiB
C++
// Support for atomic operations -*- C++ -*-
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// Copyright (C) 2004-2017 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file ext/atomicity.h
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* This file is a GNU extension to the Standard C++ Library.
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*/
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#ifndef _GLIBCXX_ATOMICITY_H
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#define _GLIBCXX_ATOMICITY_H 1
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#pragma GCC system_header
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#include <bits/c++config.h>
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#include <bits/gthr.h>
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#include <bits/atomic_word.h>
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namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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// Functions for portable atomic access.
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// To abstract locking primitives across all thread policies, use:
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// __exchange_and_add_dispatch
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// __atomic_add_dispatch
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#ifdef _GLIBCXX_ATOMIC_BUILTINS
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static inline _Atomic_word
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__exchange_and_add(volatile _Atomic_word* __mem, int __val)
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{ return __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); }
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static inline void
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__atomic_add(volatile _Atomic_word* __mem, int __val)
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{ __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); }
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#else
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_Atomic_word
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__attribute__ ((__unused__))
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__exchange_and_add(volatile _Atomic_word*, int) throw ();
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void
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__attribute__ ((__unused__))
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__atomic_add(volatile _Atomic_word*, int) throw ();
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#endif
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static inline _Atomic_word
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__exchange_and_add_single(_Atomic_word* __mem, int __val)
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{
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_Atomic_word __result = *__mem;
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*__mem += __val;
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return __result;
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}
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static inline void
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__atomic_add_single(_Atomic_word* __mem, int __val)
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{ *__mem += __val; }
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static inline _Atomic_word
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__attribute__ ((__unused__))
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__exchange_and_add_dispatch(_Atomic_word* __mem, int __val)
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{
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#ifdef __GTHREADS
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if (__gthread_active_p())
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return __exchange_and_add(__mem, __val);
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else
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return __exchange_and_add_single(__mem, __val);
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#else
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return __exchange_and_add_single(__mem, __val);
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#endif
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}
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static inline void
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__attribute__ ((__unused__))
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__atomic_add_dispatch(_Atomic_word* __mem, int __val)
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{
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#ifdef __GTHREADS
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if (__gthread_active_p())
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__atomic_add(__mem, __val);
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else
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__atomic_add_single(__mem, __val);
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#else
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__atomic_add_single(__mem, __val);
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#endif
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}
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace
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// Even if the CPU doesn't need a memory barrier, we need to ensure
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// that the compiler doesn't reorder memory accesses across the
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// barriers.
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#ifndef _GLIBCXX_READ_MEM_BARRIER
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#define _GLIBCXX_READ_MEM_BARRIER __atomic_thread_fence (__ATOMIC_ACQUIRE)
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#endif
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#ifndef _GLIBCXX_WRITE_MEM_BARRIER
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#define _GLIBCXX_WRITE_MEM_BARRIER __atomic_thread_fence (__ATOMIC_RELEASE)
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#endif
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#endif
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