RFR: 8217747: ZGC: Minor optimization of ZLoadBarrierStubC1
per.liden at oracle.com
Tue Jan 29 09:28:00 UTC 2019
On 01/29/2019 10:24 AM, Erik Österlund wrote:
> Hi Per,
> While I think this optimization is going to be completely invisible in
> all profiles, I don't mind it either. Looks good.
Thanks for reviewing, Erik. I agree, I mostly just found it annoying to
see those push/pop when inspecting the generated code.
> 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
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