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-rw-r--r--ChangeLog4
-rw-r--r--include/atomic.h9
2 files changed, 13 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog
index 1e63a386fe..205da062e6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2016-08-05 Torvald Riegel <triegel@redhat.com>
+
+ * include/atomic.h (atomic_exchange_relaxed): New.
+
2016-08-04 Joseph Myers <joseph@codesourcery.com>
* math/e_scalb.c: Do not include <fenv.h>.
diff --git a/include/atomic.h b/include/atomic.h
index ad3db2562e..129ee24426 100644
--- a/include/atomic.h
+++ b/include/atomic.h
@@ -588,6 +588,9 @@ void __atomic_link_error (void);
__atomic_compare_exchange_n ((mem), (expected), (desired), 1, \
__ATOMIC_RELEASE, __ATOMIC_RELAXED); })
+# define atomic_exchange_relaxed(mem, desired) \
+ ({ __atomic_check_size((mem)); \
+ __atomic_exchange_n ((mem), (desired), __ATOMIC_RELAXED); })
# define atomic_exchange_acquire(mem, desired) \
({ __atomic_check_size((mem)); \
__atomic_exchange_n ((mem), (desired), __ATOMIC_ACQUIRE); })
@@ -684,6 +687,12 @@ void __atomic_link_error (void);
*(expected) == __atg103_expected; })
# endif
+/* XXX Fall back to acquire MO because archs do not define a weaker
+ atomic_exchange. */
+# ifndef atomic_exchange_relaxed
+# define atomic_exchange_relaxed(mem, val) \
+ atomic_exchange_acq ((mem), (val))
+# endif
# ifndef atomic_exchange_acquire
# define atomic_exchange_acquire(mem, val) \
atomic_exchange_acq ((mem), (val))