// cond: umagicOK16(c) && config.RegSize == 8
	// result: (Trunc64to16 (Rsh64Ux64 <typ.UInt64> (Mul64 <typ.UInt64> (Const64 <typ.UInt64> [int64(1<<16+umagic16(c).m)]) (ZeroExt16to64 x)) (Const64 <typ.UInt64> [16+umagic16(c).s])))
	for {
		x := v_0
		if v_1.Op != OpConst16 {
			break
		}
		c := auxIntToInt16(v_1.AuxInt)
		if !(umagicOK16(c) && config.RegSize == 8) {
			break
		}