RFR: AArch64: org.openjdk.jcstress.tests.varhandles.DekkerTest fails

[John Rose]

I agree with this reasoning.  After looking at the old change and this
new tweak, I also support pushing it now.  Andrew can mark me a
reviewer if he wants an even longer reviewed-by list.  :-)

— John

On Mar 6, 2018, at 9:30 AM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
> 
> Changes are good. I think we should push it into JDK 10.
> It reversed optimization done by JDK-8181211 in JDK 10 - it is regression in JDK 10.
> 
> The fix prevents, for example, volatile loads float above membars - this is not aarch64 specific problem.
> 
> I will update bug report later after testing finished.
> 
> Thanks,
> Vladimir
> 
> On 3/6/18 8:24 AM, mark.reinhold at oracle.com wrote:
>> 2018/3/6 4:23:07 -0800, adinn at redhat.com:
>>> Could someone please review the following patch to /shared code/ which
>>> fixes an AArch64 breakage that was inadvertently introduced by JDK-8181211:
>>> 
>>>   webrev: http://cr.openjdk.java.net/~adinn/8198950/webrev.00
>>>   JIRA: https://bugs.openjdk.java.net/browse/JDK-8198950
>>> 
>>> The patch applies to jdk/hs. It also applies cleanly to jdk/jdk10.
>>> 
>>> I would like it to be considered for inclusion in jdk10 if at all
>>> possible because it patches a critical error in handling of volatile
>>> reads that may result in incorrect memory synchronization.
>> Andrew -- thanks for the thorough analysis.
>> So far Tobias and Roland have reviewed your change.  I'm not qualified
>> to review it myself, so since it's very late in the game for JDK 10 I'd
>> like to see reviews from at least a couple more C2 committers before we
>> make a call on this.
>> - Mark