mips.c (mips_loongson_ext2_prefetch_cookie): Handle unused argument better.

	* config/mips/mips.c (mips_loongson_ext2_prefetch_cookie): Handle
	unused argument better.  Add gcc_unreachable to silence warning.

From-SVN: r265986

gcc/ChangeLog

+2018-11-09  Jeff Law  <law@redhat.com>
+
+	* config/mips/mips.c (mips_loongson_ext2_prefetch_cookie): Handle
+	unused argument better.  Add gcc_unreachable to silence warning.
+
 2018-11-09  Martin Sebor  <msebor@redhat.com>
 
 	PR middle-end/81824

gcc/config/mips/mips.c

@@ -15155,7 +15155,7 @@ mips_prefetch_cookie (rtx write, rtx locality)
    (prefetch for store), other hint just scale to hint = 0 and hint = 1.  */
 
 rtx
-mips_loongson_ext2_prefetch_cookie (rtx write, rtx locality)
+mips_loongson_ext2_prefetch_cookie (rtx write, rtx)
 {
   /* store.  */
   if (INTVAL (write) == 1)
@@ -15164,6 +15164,8 @@ mips_loongson_ext2_prefetch_cookie (rtx write, rtx locality)
   /* load.  */
   if (INTVAL (write) == 0)
     return GEN_INT (INTVAL (write));
+
+  gcc_unreachable ();
 }