RFR: 8217747: ZGC: Minor optimization of ZLoadBarrierStubC1

Erik Österlund erik.osterlund at oracle.com
Tue Jan 29 09:24:33 UTC 2019

Hi Per,

While I think this optimization is going to be completely invisible in 
all profiles, I don't mind it either. Looks good.


On 2019-01-28 09:56, Per Liden wrote:
> In the C1 load barrier stub for ZGC we currently save/restore rax unless 
> it's the stub result register. However, we can also avoid this 
> save/restore of rax if it's the tmp register. Avoiding a push/pop in the 
> stub isn't really an important optimization, but since we already do it 
> for the result register we can just as well do it for the tmp register 
> too, without making the code more complex.
> Bug: https://bugs.openjdk.java.net/browse/JDK-8217747
> Webrev: http://cr.openjdk.java.net/~pliden/8217747/webrev.0
> /Per

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