popcnt false data dependency on recent intel

[Vitaly Davidovich]

Awesome, thanks Aleksey.  Interesting to know what you discover.

Sent from my phone
On Aug 19, 2014 7:45 AM, "Aleksey Shipilev" <aleksey.shipilev at oracle.com>
wrote:

> On 08/18/2014 07:20 PM, Vitaly Davidovich wrote:
> > Came across this SO thread recently:
> >
> http://stackoverflow.com/questions/25078285/replacing-a-32-bit-loop-count-variable-with-64-bit-introduces-crazy-performance
> >
> > I know hotspot has intrinsic that emits popcnt so thought I'd share in
> > case similar adjustment needs to be made to hotspot compilers.
>
> Thanks, submitted:
>   https://bugs.openjdk.java.net/browse/JDK-8055394
>
> Let me see if I can munge Hotspot codegen into reproducing and fixing
> the issue, if it's real.
>
> -Aleksey.
>
>
>
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