It's an interesting point. I guess ARM must have done quite a lot of analysis running up to the launch of aarch64 in 2010 when, with roughly a blank sheet of pa

It's an interesting point. I guess ARM must have done quite a lot of analysis running up to the launch of aarch64 in 2010 when, with roughly a blank sheet of paper on the ISA, they could have decided to go for variable length instructions for this reason (especially given their history with Thumb). On the other hand presumably the focus was on power given the immediate market and so the simpler decode would have been beneficial for that reason.