RFR: JDK-8141634 Implement VarHandles/Unsafe intrinsics on SPARC

[David Holmes]

Hi Trevor,

Not a full review as I'm not familiar with .ad file syntax and 
structure. Two observations:

1. We no longer support 32-bit so that code could be elided.
2. supports_cx8 is true for sparc so doesn't need to verified in sparc 
specific code (it is intended for use in shared code).

Cheers,
David

On 26/08/2016 12:01 AM, Trevor Watson wrote:
> Hi All,
>
> Please can I get a review of these updates to sparc.ad which adds in the
> C2 compareAndExchange intriniscs for int, long, pointer and object?
>
> I've run the hotspot jtreg tests locally and the JPRT hotspot tests
> successfully.
>
> The implementation of these intrinsics gives a 9x to 20x performance
> improvement for compareAndExchange operatios.
>
> http://cr.openjdk.java.net/~alanbur/JDK-8141634/
>
> Thanks,
> Trevor