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1 /* atomic.c -- Support for atomic functions if not present.
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2 Copyright (C) 2013-2020 Free Software Foundation, Inc.
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3 Written by Ian Lance Taylor, Google.
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4
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5 Redistribution and use in source and binary forms, with or without
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6 modification, are permitted provided that the following conditions are
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7 met:
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8
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9 (1) Redistributions of source code must retain the above copyright
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10 notice, this list of conditions and the following disclaimer.
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11
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12 (2) Redistributions in binary form must reproduce the above copyright
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13 notice, this list of conditions and the following disclaimer in
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14 the documentation and/or other materials provided with the
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15 distribution.
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16
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17 (3) The name of the author may not be used to
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18 endorse or promote products derived from this software without
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19 specific prior written permission.
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20
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21 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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22 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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23 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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24 DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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25 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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26 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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27 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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28 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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29 STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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30 IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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31 POSSIBILITY OF SUCH DAMAGE. */
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32
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33 #include "config.h"
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34
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35 #include <sys/types.h>
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36
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37 #include "backtrace.h"
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38 #include "backtrace-supported.h"
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39 #include "internal.h"
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40
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41 /* This file holds implementations of the atomic functions that are
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42 used if the host compiler has the sync functions but not the atomic
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43 functions, as is true of versions of GCC before 4.7. */
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44
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45 #if !defined (HAVE_ATOMIC_FUNCTIONS) && defined (HAVE_SYNC_FUNCTIONS)
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46
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47 /* Do an atomic load of a pointer. */
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48
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49 void *
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50 backtrace_atomic_load_pointer (void *arg)
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51 {
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52 void **pp;
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53 void *p;
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54
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55 pp = (void **) arg;
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56 p = *pp;
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57 while (!__sync_bool_compare_and_swap (pp, p, p))
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58 p = *pp;
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59 return p;
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60 }
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61
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62 /* Do an atomic load of an int. */
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63
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64 int
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65 backtrace_atomic_load_int (int *p)
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66 {
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67 int i;
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68
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69 i = *p;
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70 while (!__sync_bool_compare_and_swap (p, i, i))
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71 i = *p;
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72 return i;
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73 }
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74
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75 /* Do an atomic store of a pointer. */
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76
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77 void
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78 backtrace_atomic_store_pointer (void *arg, void *p)
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79 {
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80 void **pp;
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81 void *old;
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82
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83 pp = (void **) arg;
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84 old = *pp;
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85 while (!__sync_bool_compare_and_swap (pp, old, p))
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86 old = *pp;
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87 }
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88
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89 /* Do an atomic store of a size_t value. */
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90
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91 void
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92 backtrace_atomic_store_size_t (size_t *p, size_t v)
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93 {
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94 size_t old;
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95
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96 old = *p;
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97 while (!__sync_bool_compare_and_swap (p, old, v))
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98 old = *p;
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99 }
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100
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101 /* Do an atomic store of a int value. */
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102
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103 void
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104 backtrace_atomic_store_int (int *p, int v)
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105 {
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106 size_t old;
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107
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108 old = *p;
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109 while (!__sync_bool_compare_and_swap (p, old, v))
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110 old = *p;
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111 }
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112
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113 #endif
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