always define HAVE_memory_barrier

gcc/ChangeLog:

2015-05-23  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>

	* defaults.h (gen_memory_barrier): New function.
	(HAVE_memory_barrier): Add default value.
	* optabs.c: Adjust.

From-SVN: r223621

gcc/ChangeLog

 2015-05-23  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>
 
+	* defaults.h (gen_memory_barrier): New function.
+	(HAVE_memory_barrier): Add default value.
+	* optabs.c: Adjust.
+
+2015-05-23  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>
+
 	* defaults.h (gen_mem_thread_fence): New function.
 	(HAVE_mem_thread_fence): Add default definition.
 	* optabs.c: Adjust.

gcc/defaults.h

@@ -1454,6 +1454,16 @@ gen_mem_thread_fence (rtx)
 }
 #endif
 
+#ifndef HAVE_memory_barrier
+#define HAVE_memory_barrier 0
+static inline rtx
+gen_memory_barrier ()
+{
+  gcc_unreachable ();
+  return NULL;
+}
+#endif
+
 #endif /* GCC_INSN_FLAGS_H  */
 
 #endif  /* ! GCC_DEFAULTS_H */

gcc/optabs.c

@@ -7589,11 +7589,6 @@ expand_asm_memory_barrier (void)
 /* This routine will either emit the mem_thread_fence pattern or issue a 
    sync_synchronize to generate a fence for memory model MEMMODEL.  */
 
-#ifndef HAVE_memory_barrier
-# define HAVE_memory_barrier 0
-# define gen_memory_barrier()  (gcc_unreachable (), NULL_RTX)
-#endif
-
 void
 expand_mem_thread_fence (enum memmodel model)
 {