popcnt false data dependency on recent intel

[Aleksey Shipilev]

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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