On 12/4/06, Robin Garner <[EMAIL PROTECTED]> wrote:
> On 11/30/06, Robin Garner <[EMAIL PROTECTED]> wrote:
>> Xiao-Feng Li wrote:
>> >
>> > /* If the slot is in NOS or the target is not in NOS, we simply
>> > return*/
>> > if( p_slot.GE( NOS_BOUNDARY) || p_target.LT( NOS_BOUNDARY) )
>> > return;
>> >
>> > /* Otherwise, we need remember it in native code. */
>> > VMHelper.WriteBarrierSlotRem(p_slot, p_target);
>>
>> Shouldn't this be
>> if( p_slot.LT( NOS_BOUNDARY) && p_target.GE( NOS_BOUNDARY) )
>> VMHelper.WriteBarrierSlotRem(p_slot, p_target);
>>
>> ?? Ie we're recording old-to-new pointers.
>
> Robin, aren't they the same but exchanging the two branches of
> condition checking? :-)
Yes, of course. Doh. !(A|B) = !A&!B.
I do think the second is clearer though :)
Since I somehow am not a branch predictor fun, I am used to put the
common TRUE case in the branch condition so that the fast path can be
scheduled as fall-through branch automatically by the JIT. This might
be very old and obsolete C programming wisdom. :-)
> Thanks,
> xiaofeng
>
>>
>>
>> --
>> Robin Garner
>> Dept. of Computer Science
>> Australian National University
>> http://cs.anu.edu.au/people/Robin.Garner/
>>
>
