- /* For integer multiplication, the MUL uses the low 16 bits
- * of one of the operands (src0 on gen6, src1 on gen7). The
- * MACH accumulates in the contribution of the upper 16 bits
- * of that operand.
- *
- * FINISHME: Emit just the MUL if we know an operand is small
- * enough.
- */
- struct brw_reg acc = retype(brw_acc_reg(), BRW_REGISTER_TYPE_D);
-
- emit(MUL(acc, op[0], op[1]));
- emit(MACH(dst_null_d(), op[0], op[1]));
- emit(MOV(result_dst, src_reg(acc)));
+ /* For integer multiplication, the MUL uses the low 16 bits of one of
+ * the operands (src0 through SNB, src1 on IVB and later). The MACH
+ * accumulates in the contribution of the upper 16 bits of that
+ * operand. If we can determine that one of the args is in the low
+ * 16 bits, though, we can just emit a single MUL.
+ */
+ if (is_16bit_constant(ir->operands[0])) {
+ if (intel->gen < 7)
+ emit(MUL(result_dst, op[0], op[1]));
+ else
+ emit(MUL(result_dst, op[1], op[0]));
+ } else if (is_16bit_constant(ir->operands[1])) {
+ if (intel->gen < 7)
+ emit(MUL(result_dst, op[1], op[0]));
+ else
+ emit(MUL(result_dst, op[0], op[1]));
+ } else {
+ struct brw_reg acc = retype(brw_acc_reg(), BRW_REGISTER_TYPE_D);
+
+ emit(MUL(acc, op[0], op[1]));
+ emit(MACH(dst_null_d(), op[0], op[1]));
+ emit(MOV(result_dst, src_reg(acc)));
+ }