RFR: 8217747: ZGC: Minor optimization of ZLoadBarrierStubC1

[Per Liden]

Thanks Nils!

/Per


On 01/28/2019 10:27 AM, Nils Eliasson wrote:
> Looks good,
> 
> // Nils
> 
> 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