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diff --git a/gc-7.2/libatomic_ops/src/atomic_ops/sysdeps/gcc/s390.h b/gc-7.2/libatomic_ops/src/atomic_ops/sysdeps/gcc/s390.h
new file mode 100644
index 0000000..c05dc85
--- /dev/null
+++ b/gc-7.2/libatomic_ops/src/atomic_ops/sysdeps/gcc/s390.h
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
+ * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
+ * Copyright (c) 1999-2003 by Hewlett-Packard Company. All rights reserved.
+ *
+ *
+ * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
+ * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
+ *
+ * Permission is hereby granted to use or copy this program
+ * for any purpose,  provided the above notices are retained on all copies.
+ * Permission to modify the code and to distribute modified code is granted,
+ * provided the above notices are retained, and a notice that the code was
+ * modified is included with the above copyright notice.
+ *
+ */
+
+/* FIXME: untested.                                             */
+/* The relevant documentation appears to be at                  */
+/* http://publibz.boulder.ibm.com/epubs/pdf/dz9zr003.pdf        */
+/* around page 5-96.  Apparently:                               */
+/* - Memory references in general are atomic only for a single  */
+/*   byte.  But it appears that the most common load/store      */
+/*   instructions also guarantee atomicity for aligned          */
+/*   operands of standard types.  WE FOOLISHLY ASSUME that      */
+/*   compilers only generate those.  If that turns out to be    */
+/*   wrong, we need inline assembly code for AO_load and        */
+/*   AO_store.                                                  */
+/* - A store followed by a load is unordered since the store    */
+/*   may be delayed.  Otherwise everything is ordered.          */
+/* - There is a hardware compare-and-swap (CS) instruction.     */
+
+#include "../ordered_except_wr.h"
+#include "../all_aligned_atomic_load_store.h"
+
+#include "../test_and_set_t_is_ao_t.h"
+/* FIXME: Is there a way to do byte-sized test-and-set? */
+
+/* FIXME: AO_nop_full should probably be implemented directly.  */
+/* It appears that certain BCR instructions have that effect.   */
+/* Presumably they're cheaper than CS?                          */
+
+AO_INLINE int AO_compare_and_swap_full(volatile AO_t *addr,
+                                       AO_t old, AO_t new_val)
+{
+  int retval;
+  __asm__ __volatile__ (
+# ifndef __s390x__
+    "     cs  %1,%2,0(%3)\n"
+# else
+    "     csg %1,%2,0(%3)\n"
+# endif
+  "     ipm %0\n"
+  "     srl %0,28\n"
+  : "=&d" (retval), "+d" (old)
+  : "d" (new_val), "a" (addr)
+  : "cc", "memory");
+  return retval == 0;
+}
+#define AO_HAVE_compare_and_swap_full
+
+/* FIXME: Add double-wide compare-and-swap for 32-bit executables.      */