diff -Naur libatomic_ops-7.6.12.org/src/Makefile.am libatomic_ops-7.6.12.sw/src/Makefile.am
--- libatomic_ops-7.6.12.org/src/Makefile.am	2022-02-26 02:35:27.760000000 +0000
+++ libatomic_ops-7.6.12.sw/src/Makefile.am	2022-02-26 02:38:49.230000000 +0000
@@ -81,6 +81,7 @@
         \
           atomic_ops/sysdeps/gcc/aarch64.h \
           atomic_ops/sysdeps/gcc/alpha.h \
+          atomic_ops/sysdeps/gcc/sw_64.h \
           atomic_ops/sysdeps/gcc/arm.h \
           atomic_ops/sysdeps/gcc/avr32.h \
           atomic_ops/sysdeps/gcc/cris.h \
diff -Naur libatomic_ops-7.6.12.org/src/atomic_ops/sysdeps/gcc/sw_64.h libatomic_ops-7.6.12.sw/src/atomic_ops/sysdeps/gcc/sw_64.h
--- libatomic_ops-7.6.12.org/src/atomic_ops/sysdeps/gcc/sw_64.h	1970-01-01 00:00:00.000000000 +0000
+++ libatomic_ops-7.6.12.sw/src/atomic_ops/sysdeps/gcc/sw_64.h	2022-02-26 02:41:18.020000000 +0000
@@ -0,0 +1,70 @@
+/*
+ * 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.
+ *
+ */
+
+#include "../loadstore/atomic_load.h"
+#include "../loadstore/atomic_store.h"
+
+#include "../test_and_set_t_is_ao_t.h"
+
+#define AO_NO_DD_ORDERING
+        /* Data dependence does not imply read ordering.        */
+
+AO_INLINE void
+AO_nop_full(void)
+{
+  __asm__ __volatile__("memb" : : : "memory");
+}
+#define AO_HAVE_nop_full
+
+AO_INLINE void
+AO_nop_write(void)
+{
+  __asm__ __volatile__("memb" : : : "memory");
+}
+#define AO_HAVE_nop_write
+
+/* mb should be used for AO_nop_read().  That's the default.    */
+
+/* TODO: implement AO_fetch_and_add explicitly. */
+
+/* We believe that ldq_l ... stq_c does not imply any memory barrier.   */
+AO_INLINE int
+AO_compare_and_swap(volatile AO_t *addr,
+                    AO_t old, AO_t new_val)
+{
+  unsigned long was_equal;
+  unsigned long temp;
+
+  __asm__ __volatile__(
+                     "       ldi %3,%1\n"
+                     "1:     lldl %0,0(%3)\n"
+                     "       cmpeq %0,%5,%2\n"
+                     "       wr_f %2\n"
+                     "       mov %4,%0\n"
+                     "       lstl %0,0(%3)\n"
+                     "       rd_f %0\n"
+                     "       beq %2,2f\n"
+                     "       beq %0,1b\n"
+                     "2:\n"
+                     : "=&r" (temp), "+m" (*addr), "=&r" (was_equal),"=&r"(temp)
+                     : "r" (new_val), "Ir" (old)
+                     :"memory");
+  return (int)was_equal;
+}
+#define AO_HAVE_compare_and_swap
+
+/* TODO: implement AO_fetch_compare_and_swap */
diff -Naur libatomic_ops-7.6.12.org/src/atomic_ops.h libatomic_ops-7.6.12.sw/src/atomic_ops.h
--- libatomic_ops-7.6.12.org/src/atomic_ops.h	2022-02-26 02:35:27.770000000 +0000
+++ libatomic_ops-7.6.12.sw/src/atomic_ops.h	2022-02-26 02:36:05.400000000 +0000
@@ -310,6 +310,8 @@
 # elif defined(__hppa__)
 #   include "atomic_ops/sysdeps/gcc/hppa.h"
 #   define AO_CAN_EMUL_CAS
+# elif defined(__sw_64__)
+#   include "atomic_ops/sysdeps/gcc/sw_64.h"
 # elif defined(__alpha__)
 #   include "atomic_ops/sysdeps/gcc/alpha.h"
 #   define AO_GENERALIZE_TWICE
diff -Naur libatomic_ops-7.6.12.org/src/atomic_ops_stack.c libatomic_ops-7.6.12.sw/src/atomic_ops_stack.c
--- libatomic_ops-7.6.12.org/src/atomic_ops_stack.c	2022-02-26 02:35:27.760000000 +0000
+++ libatomic_ops-7.6.12.sw/src/atomic_ops_stack.c	2022-02-26 02:38:24.530000000 +0000
@@ -180,7 +180,7 @@
   /* We need to make sure that first is still the first entry on the    */
   /* list.  Otherwise it's possible that a reinsertion of it was        */
   /* already started before we added the black list entry.              */
-# if defined(__alpha__) && (__GNUC__ == 4)
+# if (defined(__alpha__) || defined(__sw_64__)) && (__GNUC__ == 4)
     if (first != AO_load_acquire(list))
                         /* Workaround __builtin_expect bug found in     */
                         /* gcc-4.6.3/alpha causing test_stack failure.  */
@@ -196,7 +196,7 @@
   }
   first_ptr = AO_REAL_NEXT_PTR(first);
   next = AO_load_next(first_ptr);
-# if defined(__alpha__) && (__GNUC__ == 4)
+# if (defined(__alpha__) || defined(__sw_64__)) && (__GNUC__ == 4)
     if (!AO_compare_and_swap_release(list, first, next))
 # else
     if (AO_EXPECT_FALSE(!AO_compare_and_swap_release(list, first, next)))