[8u] RFR (M) 8181809 PPC64: Leverage mtfprd/mffprd on POWER8

[Matthew Brandyberry]

[Ping]

On 9/28/17 12:53 PM, Matthew Brandyberry wrote:
> Hi,
>
> Please review this backport of 8181809 for jdk8u.
>
> It applies cleanly to jdk8u except for the lack of C1 support on PPC 
> in 8u -- thus those changes are omitted here.
>
> This is a PPC-specific hotspot optimization that leverages the 
> mtfprd/mffprd instructions for for movement between general purpose 
> and floating point registers (rather than through memory). It yields a 
> ~35% improvement measured via a microbenchmark.
>
> webrev       :http://cr.openjdk.java.net/~mbrandy/8181809/jdk8u/v1
>
> bug          :https://bugs.openjdk.java.net/browse/JDK-8181809
>
> review 
> thread:http://mail.openjdk.java.net/pipermail/hotspot-dev/2017-June/027226.html
>
>
> Thank you.
> -Matt
>