gcc/libstdc++-v3/libsupc++/eh_atomics.h

85 lines
2.5 KiB
C++

// Exception Handling support header for -*- C++ -*-
// Copyright (C) 2016-2017 Free Software Foundation, Inc.
//
// This file is part of GCC.
//
// GCC is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3, or (at your option)
// any later version.
//
// GCC is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file eh_atomics.h
* This is an internal header file, included by library source files.
* Do not attempt to use it directly.
*/
#ifndef _EH_ATOMICS_H
#define _EH_ATOMICS_H 1
#include <bits/c++config.h>
#include <bits/atomic_word.h>
#include <bits/atomic_lockfree_defines.h>
#if ATOMIC_INT_LOCK_FREE <= 1
# include <ext/atomicity.h>
#endif
#pragma GCC visibility push(default)
extern "C++" {
namespace __gnu_cxx
{
void
__eh_atomic_inc (_Atomic_word* __count) __attribute__((always_inline));
bool
__eh_atomic_dec (_Atomic_word* __count) __attribute__((always_inline));
// Increments the count.
inline void
__eh_atomic_inc (_Atomic_word* __count)
{
#if ATOMIC_INT_LOCK_FREE > 1
__atomic_add_fetch (__count, 1, __ATOMIC_ACQ_REL);
#else
_GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE (__count);
__gnu_cxx::__atomic_add_dispatch (__count, 1);
_GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER (__count);
#endif
}
// Decrements the count and returns true if it reached zero.
inline bool
__eh_atomic_dec (_Atomic_word* __count)
{
#if ATOMIC_INT_LOCK_FREE > 1
return __atomic_sub_fetch (__count, 1, __ATOMIC_ACQ_REL) == 0;
#else
_GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE (__count);
if (__gnu_cxx::__exchange_and_add_dispatch (__count, -1) == 1)
{
_GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER (__count);
return true;
}
return false;
#endif
}
} // namespace __gnu_cxx
}
#pragma GCC visibility pop
#endif // _EH_ATOMICS_H