1// Exception Handling support header for -*- C++ -*-
2
3// Copyright (C) 2016-2017 Free Software Foundation, Inc.
4//
5// This file is part of GCC.
6//
7// GCC is free software; you can redistribute it and/or modify
8// it 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// GCC is distributed in the hope that it will be useful,
13// but WITHOUT ANY WARRANTY; without even the implied warranty of
14// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15// GNU General Public License for 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/** @file eh_atomics.h
27 * This is an internal header file, included by library source files.
28 * Do not attempt to use it directly.
29 */
30
31#ifndef _EH_ATOMICS_H
32#define _EH_ATOMICS_H 1
33
34#include <bits/c++config.h>
35#include <bits/atomic_word.h>
36#include <bits/atomic_lockfree_defines.h>
37#if ATOMIC_INT_LOCK_FREE <= 1
38# include <ext/atomicity.h>
39#endif
40
41#pragma GCC visibility push(default)
42extern "C++" {
43namespace __gnu_cxx
44{
45 void
46 __eh_atomic_inc (_Atomic_word* __count) __attribute__((always_inline));
47
48 bool
49 __eh_atomic_dec (_Atomic_word* __count) __attribute__((always_inline));
50
51 // Increments the count.
52 inline void
53 __eh_atomic_inc (_Atomic_word* __count)
54 {
55#if ATOMIC_INT_LOCK_FREE > 1
56 __atomic_add_fetch (__count, 1, __ATOMIC_ACQ_REL);
57#else
58 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE (__count);
59 __gnu_cxx::__atomic_add_dispatch (__count, 1);
60 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER (__count);
61#endif
62 }
63
64 // Decrements the count and returns true if it reached zero.
65 inline bool
66 __eh_atomic_dec (_Atomic_word* __count)
67 {
68#if ATOMIC_INT_LOCK_FREE > 1
69 return __atomic_sub_fetch (__count, 1, __ATOMIC_ACQ_REL) == 0;
70#else
71 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE (__count);
72 if (__gnu_cxx::__exchange_and_add_dispatch (__count, -1) == 1)
73 {
74 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER (__count);
75 return true;
76 }
77 return false;
78#endif
79 }
80} // namespace __gnu_cxx
81}
82#pragma GCC visibility pop
83
84#endif // _EH_ATOMICS_H
85