[aarch64-port-dev ] barrier use in JDK11

[Andrew Haley]

On 06/13/2018 06:32 PM, Dave Nuechterlein wrote: I work for Ampere
> Computing, and am looking at the C2 code produced for some simple
> JMH benchmarks.  The code produced from jdk11 seems to have many
> more DMBs than the jdk8u Aarch64 port.  I think this is probably
> related to the controls for using barriers instead of
> LoadAcquire/StoreRelease for volatile variables.  I want to switch
> the "use barriers for volatile variable switch", but I wanted to
> know more about why it is there, and what the pitfalls might be.
> 
> Any suggestions/comments?

Hard to say.  Please post an example; please make it the shortest one
you can find.  If the examples are too big, please put them on a web
site somewhere.

It helps a lot to use a debug build.

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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