operand isolation in RTL
This might save toggle power, but only in this module, and only before this logic is used once. You've spent a flop doing that, and added some gates. I don't think this is useful (but I don't have visibility of your whole system).

You would be better off clamping the in1, in2 at source, and more frequently. Even better is gating the clock to a clop that drives them (you only need a single AND, plus it saves both clock and signal toggle power)