That immediately jumped out to me as well. I'm not sure their scheme can easily support a "hand decrement" instruction, either, since then the reused physical r

That immediately jumped out to me as well. I'm not sure their scheme can easily support a "hand decrement" instruction, either, since then the reused physical register might still have OoO instructions in flight using it and you're forced to stall, like they are doing if they loop around the hand ring buffer. You could have an instruction that pushes all of v[0]-v[7] to memory and restores it, like arm32 ldmia/stmdb, I guess?