Review request: 8015486: PSScavenge::is_obj_in_young is unnecessarily slow with UseCompressedOops

[Bengt Rutisson]

Looks good, Stefan!

Nice improvement!
Bengt

On 5/30/13 11:14 AM, Stefan Karlsson wrote:
> http://cr.openjdk.java.net/~stefank/8015486/webrev.00/
>
> 8015486: PSScavenge::is_obj_in_young is unnecessarily slow with 
> UseCompressedOops
> Summary: Compare compressed oops to a compressed young gen boundary 
> instead of uncompressing the oops before doing the young gen boundary 
> check.
>
> Instead of decompressing every single oop before checking against the 
> young gen boundary, we could store a compressed young gen boundary and 
> compare the compressed oops against that value. This will save both a 
> null-check and the decompression code for all the visited oops.
>
> This give about 3% lower young GC times when running SPECjbb2005.
>
> StefanK