--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libbacktrace/atomic.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,113 @@
+/* atomic.c -- Support for atomic functions if not present.
+   Copyright (C) 2013-2017 Free Software Foundation, Inc.
+   Written by Ian Lance Taylor, Google.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    (1) Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+    (2) Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in
+    the documentation and/or other materials provided with the
+    distribution.
+
+    (3) The name of the author may not be used to
+    endorse or promote products derived from this software without
+    specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.  */
+
+#include "config.h"
+
+#include <sys/types.h>
+
+#include "backtrace.h"
+#include "backtrace-supported.h"
+#include "internal.h"
+
+/* This file holds implementations of the atomic functions that are
+   used if the host compiler has the sync functions but not the atomic
+   functions, as is true of versions of GCC before 4.7.  */
+
+#if !defined (HAVE_ATOMIC_FUNCTIONS) && defined (HAVE_SYNC_FUNCTIONS)
+
+/* Do an atomic load of a pointer.  */
+
+void *
+backtrace_atomic_load_pointer (void *arg)
+{
+  void **pp;
+  void *p;
+
+  pp = (void **) arg;
+  p = *pp;
+  while (!__sync_bool_compare_and_swap (pp, p, p))
+    p = *pp;
+  return p;
+}
+
+/* Do an atomic load of an int.  */
+
+int
+backtrace_atomic_load_int (int *p)
+{
+  int i;
+
+  i = *p;
+  while (!__sync_bool_compare_and_swap (p, i, i))
+    i = *p;
+  return i;
+}
+
+/* Do an atomic store of a pointer.  */
+
+void
+backtrace_atomic_store_pointer (void *arg, void *p)
+{
+  void **pp;
+  void *old;
+
+  pp = (void **) arg;
+  old = *pp;
+  while (!__sync_bool_compare_and_swap (pp, old, p))
+    old = *pp;
+}
+
+/* Do an atomic store of a size_t value.  */
+
+void
+backtrace_atomic_store_size_t (size_t *p, size_t v)
+{
+  size_t old;
+
+  old = *p;
+  while (!__sync_bool_compare_and_swap (p, old, v))
+    old = *p;
+}
+
+/* Do an atomic store of a int value.  */
+
+void
+backtrace_atomic_store_int (int *p, int v)
+{
+  size_t old;
+
+  old = *p;
+  while (!__sync_bool_compare_and_swap (p, old, v))
+    old = *p;
+}
+
+#endif