[NDS32] Adjust BRANCH_COST to prevent too much jump when compile with -Os.

gcc/
	* config/nds32/nds32.h (BRANCH_COST): Adjust cost.

From-SVN: r258921

gcc/ChangeLog

+2018-03-27  Chung-Ju Wu  <jasonwucj@gmail.com>
+
+	* config/nds32/nds32.h (BRANCH_COST): Adjust cost.
+
 2018-03-27  Michael Meissner  <meissner@linux.vnet.ibm.com>
 
 	PR target/84914

gcc/config/nds32/nds32.h

@@ -865,7 +865,7 @@ enum reg_class
 /* A C expression for the cost of a branch instruction.
    A value of 1 is the default;
    other values are interpreted relative to that.  */
-#define BRANCH_COST(speed_p, predictable_p) ((speed_p) ? 2 : 0)
+#define BRANCH_COST(speed_p, predictable_p) ((speed_p) ? 2 : 1)
 
 /* Override BRANCH_COST heuristic which empirically produces worse
    performance for removing short circuiting from the logical ops.  */