[ARC] Update ARC600 multiplication cost.

gcc/
xxxx-xx-xx  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/arc/arc.c (arc_rtx_costs): Update mul64 cost.

gcc/ChangeLog

 2020-01-27  Claudiu Zissulescu  <claziss@synopsys.com>
 
+	* config/arc/arc.c (arc_rtx_costs): Update mul64 cost.
+
+2020-01-27  Claudiu Zissulescu  <claziss@synopsys.com>
+
 	* config/arc/arc-protos.h (gen_mlo): Remove.
 	(gen_mhi): Likewise.
 	* config/arc/arc.c (AUX_MULHI): Define.

gcc/config/arc/arc.c

@@ -5877,6 +5877,12 @@ arc_rtx_costs (rtx x, machine_mode mode, int outer_code,
 		  nolimm = true;
 		if (satisfies_constraint_Clo (x))
 		  nolimm = true;
+		break;
+	      case MULT:
+		if (TARGET_MUL64_SET)
+		  if (SIGNED_INT12 (INTVAL (x)))
+		    nolimm = true;
+		break;
 	      default:
 		break;
 	      }