+ /* If both sources use a constant swizzle, then we can't convert it to
+ * a presubtract operation. In fact for the ADD and SUB presubtract
+ * operations neither source can contain a constant swizzle. This
+ * specific case is checked in peephole_add_presub_add() when
+ * we make sure the swizzles for both sources are equal, so we
+ * don't need to worry about it here. */
+ for (i = 0; i < 2; i++) {
+ int chan;
+ for (chan = 0; chan < 4; chan++) {
+ rc_swizzle swz =
+ get_swz(inst->U.I.SrcReg[i].Swizzle, chan);
+ if (swz == RC_SWIZZLE_ONE
+ || swz == RC_SWIZZLE_ZERO
+ || swz == RC_SWIZZLE_HALF) {
+ is_constant[i] = 1;
+ }
+ }
+ }
+ if (is_constant[0] && is_constant[1])
+ return 0;
+