RFR: 8204479: Bitwise AND on byte value sometimes produces wrong result

[Vladimir Kozlov]

On 6/8/18 3:00 AM, Aleksey Shipilev wrote:
> On 06/08/2018 10:18 AM, Tobias Hartmann wrote:
>> Hi Aleksey,
>>
>> this looks good to me (and I think the change is trivial because it reverts a previous one).
> 
> Thank you Tobias. I pushed, adding Vladimir as second reviewer, because he came up with the same patch.

Thank you, Aleksey for pushing the fix.

> 
> I wonder separately if we could instead make matchers match rFlagsRegU cr, maybe that would help to
> match only "safe" conditional jumps? We can follow up with the redo later.

It could be more complicated change because we would need to change ideal nodes to use unsigned compare CmpUNode in case 
when we have LoadU and positive compared value. Otherwise as you noticed with your first experiment it will not match.

Regards,
Vladimir

> 
> -Aleksey
> 
>