On Wed, Feb 9, 2011 at 9:41 AM, Paolo Bonzini <pbonz...@redhat.com> wrote: > On 02/08/2011 07:05 PM, Richard Henderson wrote: >> >> (Which is probably a mistake from a translator point of view -- there's >> no reason we can't emulate 16-bit operations with 32-bit operations given >> that the high bits are ignorable.) > > Not really, you never know if the guest is going to use a 66 prefix on the > next instruction.
Perhaps similar system to current lazy condition code evaluation could be used. The translator would keep record of high bits use status, and if they are getting used, emit extra ops to clear (or recalculate?) the high bits.
