[NDS32] Define CLZ_DEFINED_VALUE_AT_ZERO.

gcc/
	* config/nds32/nds32.h (CLZ_DEFINED_VALUE_AT_ZERO): Define.

From-SVN: r258627

gcc/ChangeLog

+2018-03-18  Chung-Ju Wu  <jasonwucj@gmail.com>
+
+	* config/nds32/nds32.h (CLZ_DEFINED_VALUE_AT_ZERO): Define.
+
 2018-03-17  Chung-Ju Wu  <jasonwucj@gmail.com>
 	    Kito Cheng  <kito.cheng@gmail.com>
 

gcc/config/nds32/nds32.h

@@ -1066,6 +1066,11 @@ enum reg_class
    when the condition is true.  */
 #define STORE_FLAG_VALUE 1
 
+/* A C expression that indicates whether the architecture defines a value for
+   clz or ctz with a zero operand.  In nds32 clz for 0 result 32 is defined
+   in ISA spec */
+#define CLZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE)  ((VALUE) = 32, 1)
+
 /* An alias for the machine mode for pointers.  */
 #define Pmode SImode