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1 /* Copyright (C) 2005-2020 Free Software Foundation, Inc.
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2 Contributed by Richard Henderson <rth@redhat.com>.
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3
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111
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4 This file is part of the GNU Offloading and Multi Processing Library
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5 (libgomp).
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6
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7 Libgomp is free software; you can redistribute it and/or modify it
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8 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 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
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13 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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14 FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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15 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 /* This file handles the CRITICAL construct. */
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27
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28 #include "libgomp.h"
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29 #include <stdlib.h>
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30
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31
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32 static gomp_mutex_t default_lock;
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33
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34 void
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35 GOMP_critical_start (void)
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36 {
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37 /* There is an implicit flush on entry to a critical region. */
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38 __atomic_thread_fence (MEMMODEL_RELEASE);
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39 gomp_mutex_lock (&default_lock);
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40 }
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41
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42 void
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43 GOMP_critical_end (void)
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44 {
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45 gomp_mutex_unlock (&default_lock);
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46 }
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47
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48 #ifndef HAVE_SYNC_BUILTINS
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49 static gomp_mutex_t create_lock_lock;
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50 #endif
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51
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52 void
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53 GOMP_critical_name_start (void **pptr)
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54 {
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55 gomp_mutex_t *plock;
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56
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57 /* If a mutex fits within the space for a pointer, and is zero initialized,
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58 then use the pointer space directly. */
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59 if (GOMP_MUTEX_INIT_0
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60 && sizeof (gomp_mutex_t) <= sizeof (void *)
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61 && __alignof (gomp_mutex_t) <= sizeof (void *))
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62 plock = (gomp_mutex_t *)pptr;
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63
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64 /* Otherwise we have to be prepared to malloc storage. */
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65 else
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66 {
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67 plock = *pptr;
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68
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69 if (plock == NULL)
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70 {
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71 #ifdef HAVE_SYNC_BUILTINS
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72 gomp_mutex_t *nlock = gomp_malloc (sizeof (gomp_mutex_t));
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73 gomp_mutex_init (nlock);
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74
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75 plock = __sync_val_compare_and_swap (pptr, NULL, nlock);
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76 if (plock != NULL)
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77 {
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78 gomp_mutex_destroy (nlock);
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79 free (nlock);
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80 }
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81 else
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82 plock = nlock;
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83 #else
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84 gomp_mutex_lock (&create_lock_lock);
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85 plock = *pptr;
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86 if (plock == NULL)
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87 {
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88 plock = gomp_malloc (sizeof (gomp_mutex_t));
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89 gomp_mutex_init (plock);
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90 __sync_synchronize ();
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91 *pptr = plock;
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92 }
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93 gomp_mutex_unlock (&create_lock_lock);
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94 #endif
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95 }
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96 }
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97
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98 gomp_mutex_lock (plock);
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99 }
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100
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101 void
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102 GOMP_critical_name_end (void **pptr)
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103 {
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104 gomp_mutex_t *plock;
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105
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106 /* If a mutex fits within the space for a pointer, and is zero initialized,
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107 then use the pointer space directly. */
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108 if (GOMP_MUTEX_INIT_0
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109 && sizeof (gomp_mutex_t) <= sizeof (void *)
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110 && __alignof (gomp_mutex_t) <= sizeof (void *))
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111 plock = (gomp_mutex_t *)pptr;
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112 else
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113 plock = *pptr;
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114
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115 gomp_mutex_unlock (plock);
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116 }
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117
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118 #if !GOMP_MUTEX_INIT_0
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119 static void __attribute__((constructor))
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120 initialize_critical (void)
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121 {
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122 gomp_mutex_init (&default_lock);
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123 #ifndef HAVE_SYNC_BUILTINS
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124 gomp_mutex_init (&create_lock_lock);
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125 #endif
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126 }
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127 #endif
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