Remove the useless constant UNSPEC_VOLATILE_FUNC_RETURN.

gcc/
	* config/nds32/constants.md (UNSPEC_VOLATILE_FUNC_RETURN): Remove.

From-SVN: r254799

gcc/ChangeLog

 2017-11-16  Chung-Ju Wu  <jasonwucj@gmail.com>
+
+	* config/nds32/constants.md (UNSPEC_VOLATILE_FUNC_RETURN): Remove.
+
+2017-11-16  Chung-Ju Wu  <jasonwucj@gmail.com>
 	    Kito Cheng  <kito.cheng@gmail.com>
 
 	* config/nds32/nds32.opt: Add mext-perf, mext-perf2, mext-string.

gcc/config/nds32/constants.md

@@ -32,7 +32,6 @@
 
 ;; The unspec_volatile operation index.
 (define_c_enum "unspec_volatile_element" [
-  UNSPEC_VOLATILE_FUNC_RETURN
   UNSPEC_VOLATILE_ISYNC
   UNSPEC_VOLATILE_ISB
   UNSPEC_VOLATILE_MFSR