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1 // Exception Handling support header for -*- C++ -*-
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2
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145
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3 // Copyright (C) 2016-2020 Free Software Foundation, Inc.
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111
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4 //
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5 // This file is part of GCC.
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6 //
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7 // GCC is free software; you can redistribute it and/or modify
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8 // it under the terms of the GNU General Public License as published by
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9 // the Free Software Foundation; either version 3, or (at your option)
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10 // any later version.
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11 //
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12 // GCC is distributed in the hope that it will be useful,
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13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 // GNU General Public License for more details.
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16 //
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17 // Under Section 7 of GPL version 3, you are granted additional
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18 // permissions described in the GCC Runtime Library Exception, version
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19 // 3.1, as published by the Free Software Foundation.
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20
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21 // You should have received a copy of the GNU General Public License and
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22 // a copy of the GCC Runtime Library Exception along with this program;
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23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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24 // <http://www.gnu.org/licenses/>.
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25
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26 /** @file eh_atomics.h
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27 * This is an internal header file, included by library source files.
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28 * Do not attempt to use it directly.
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29 */
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30
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31 #ifndef _EH_ATOMICS_H
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32 #define _EH_ATOMICS_H 1
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33
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34 #include <bits/c++config.h>
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35 #include <bits/atomic_word.h>
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36 #include <bits/atomic_lockfree_defines.h>
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37 #if ATOMIC_INT_LOCK_FREE <= 1
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38 # include <ext/atomicity.h>
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39 #endif
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40
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41 #pragma GCC visibility push(default)
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42 extern "C++" {
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43 namespace __gnu_cxx
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44 {
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45 void
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46 __eh_atomic_inc (_Atomic_word* __count) __attribute__((always_inline));
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47
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48 bool
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49 __eh_atomic_dec (_Atomic_word* __count) __attribute__((always_inline));
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50
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51 // Increments the count.
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52 inline void
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53 __eh_atomic_inc (_Atomic_word* __count)
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54 {
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55 #if ATOMIC_INT_LOCK_FREE > 1
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56 __atomic_add_fetch (__count, 1, __ATOMIC_ACQ_REL);
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57 #else
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58 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE (__count);
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59 __gnu_cxx::__atomic_add_dispatch (__count, 1);
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60 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER (__count);
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61 #endif
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62 }
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63
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64 // Decrements the count and returns true if it reached zero.
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65 inline bool
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66 __eh_atomic_dec (_Atomic_word* __count)
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67 {
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68 #if ATOMIC_INT_LOCK_FREE > 1
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69 return __atomic_sub_fetch (__count, 1, __ATOMIC_ACQ_REL) == 0;
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70 #else
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71 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE (__count);
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72 if (__gnu_cxx::__exchange_and_add_dispatch (__count, -1) == 1)
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73 {
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74 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER (__count);
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75 return true;
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76 }
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77 return false;
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78 #endif
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79 }
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80 } // namespace __gnu_cxx
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81 }
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82 #pragma GCC visibility pop
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83
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84 #endif // _EH_ATOMICS_H
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