RFR (S) 8019968: Reference CAS induces GC store barrier even on failure

[Andrew Dinn]

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On 29/07/15 09:58, Aleksey Shipilev wrote:
> I would like to suggest a fix for: 
> https://bugs.openjdk.java.net/browse/JDK-8019968
> 
> In short, current reference CAS intrinsic blindly emits
> post_barrier, ignoring the CAS result. In some cases, notably
> contended CAS spin-loops, we fail the CAS a lot, and thus go for a
> post_barrier excessively. Instead, we can conditionalize on the
> result of the store itself, and put the post_barrier only on
> success path: http://cr.openjdk.java.net/~shade/8019968/webrev.01/
> 
> More performance results here: 
> http://cr.openjdk.java.net/~shade/8019968/notes.txt

Nice! The code looks fine and your test results are very convincing.
I'll be interested to see how this looks on AArch64.

That said, I am afraid you still need a Reviewer!

regards,


Andrew Dinn
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