[Eit4Choh]

Maybe just don't speculate across power domains? I.e. if a speculative execution would require bringing up the AVX2 unit that might be a bad idea anyway because it slows down everything else even if the branch is mispredicted.

Or at least execute it on the slow path if the unit is not up (lower execution width) without triggering the ramp-up as long as it is speculative. Only ramp-up when the instruction is committed.