RFR (XXS): 8026293: Schedule part of G1 pre-barrier late

[Christian Thalinger]

Looks good.

On Oct 15, 2013, at 10:52 AM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:

> http://cr.openjdk.java.net/~kvn/8026293/webrev/
> 
> https://bugs.openjdk.java.net/browse/JDK-8026293
> 
> A large part of the G1 write barrier is only used during marking, hence the code it not commonly executed.
> To make the active code segments smaller and better fit the cache these unused segments should be schedule outside of the common path.
> Setting the the first branch of the pre-barrier check to be unlikely will make the compiler treat the barrier code as cold and hence schedule it outside of the hot path.
> 
> Contributed by Staffan Friberg.
> 
> Tested JPRT, jtreg, SPECJEnt, SPECJBB.
> 
> Thanks,
> Vladimir
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