1 /* Copyright (C) 2005-2018 Free Software Foundation, Inc. 2 Contributed by Richard Henderson <rth@redhat.com>. 3 4 This file is part of the GNU Offloading and Multi Processing Library 5 (libgomp). 6 7 Libgomp is free software; you can redistribute it and/or modify it 8 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 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY 13 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 14 FOR A PARTICULAR PURPOSE. See the GNU General Public License for 15 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 /* This file handles the CRITICAL construct. */ 27 28 #include "libgomp.h" 29 #include <stdlib.h> 30 31 32 static gomp_mutex_t default_lock; 33 34 void 35 GOMP_critical_start (void) 36 { 37 /* There is an implicit flush on entry to a critical region. */ 38 __atomic_thread_fence (MEMMODEL_RELEASE); 39 gomp_mutex_lock (&default_lock); 40 } 41 42 void 43 GOMP_critical_end (void) 44 { 45 gomp_mutex_unlock (&default_lock); 46 } 47 48 #ifndef HAVE_SYNC_BUILTINS 49 static gomp_mutex_t create_lock_lock; 50 #endif 51 52 void 53 GOMP_critical_name_start (void **pptr) 54 { 55 gomp_mutex_t *plock; 56 57 /* If a mutex fits within the space for a pointer, and is zero initialized, 58 then use the pointer space directly. */ 59 if (GOMP_MUTEX_INIT_0 60 && sizeof (gomp_mutex_t) <= sizeof (void *) 61 && __alignof (gomp_mutex_t) <= sizeof (void *)) 62 plock = (gomp_mutex_t *)pptr; 63 64 /* Otherwise we have to be prepared to malloc storage. */ 65 else 66 { 67 plock = *pptr; 68 69 if (plock == NULL) 70 { 71 #ifdef HAVE_SYNC_BUILTINS 72 gomp_mutex_t *nlock = gomp_malloc (sizeof (gomp_mutex_t)); 73 gomp_mutex_init (nlock); 74 75 plock = __sync_val_compare_and_swap (pptr, NULL, nlock); 76 if (plock != NULL) 77 { 78 gomp_mutex_destroy (nlock); 79 free (nlock); 80 } 81 else 82 plock = nlock; 83 #else 84 gomp_mutex_lock (&create_lock_lock); 85 plock = *pptr; 86 if (plock == NULL) 87 { 88 plock = gomp_malloc (sizeof (gomp_mutex_t)); 89 gomp_mutex_init (plock); 90 __sync_synchronize (); 91 *pptr = plock; 92 } 93 gomp_mutex_unlock (&create_lock_lock); 94 #endif 95 } 96 } 97 98 gomp_mutex_lock (plock); 99 } 100 101 void 102 GOMP_critical_name_end (void **pptr) 103 { 104 gomp_mutex_t *plock; 105 106 /* If a mutex fits within the space for a pointer, and is zero initialized, 107 then use the pointer space directly. */ 108 if (GOMP_MUTEX_INIT_0 109 && sizeof (gomp_mutex_t) <= sizeof (void *) 110 && __alignof (gomp_mutex_t) <= sizeof (void *)) 111 plock = (gomp_mutex_t *)pptr; 112 else 113 plock = *pptr; 114 115 gomp_mutex_unlock (plock); 116 } 117 118 #if !GOMP_MUTEX_INIT_0 119 static void __attribute__((constructor)) 120 initialize_critical (void) 121 { 122 gomp_mutex_init (&default_lock); 123 #ifndef HAVE_SYNC_BUILTINS 124 gomp_mutex_init (&create_lock_lock); 125 #endif 126 } 127 #endif 128