RFR (S): 8200233: Simple G1 evacuation path performance enhancements

[Kim Barrett]

> On Mar 26, 2018, at 7:48 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> Hi all,
> 
>  can I have reviews for these very tiny (and ultimately note really
> measureable) improvements to the G1 evacuation path?
> 
> They are:
> 
> - some stores can be made OOP_NOT_NULL 
> - the path for compressed/uncompressed oops when popping elements from
> the task queue during evacuation can be specialized: compressed oops
> are never array oops so saving the useless test
> - some load of the "from" region in the evacuation path can be delayed
> and in many cases actually avoided
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8200233
> 
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8200233/webrev/
> 
> Testing:
> hs-tier-1
> 
> Thanks,
>  Thomas

Looks good.