[jmm-dev] Will the real memory read barrier please stand up?

[Stephan Diestelhorst]

On Sunday 23 November 2014 23:58:50 Doug Lea wrote:
> This is a [LoadLoad|LoadStore] fence, also known as
> a "load acquire" fence, which is sometimes (including
> inside hotspot) just called a "load fence" because it is the
> only kind of Load* fence that is ever wanted.

Doug, you are the second person to say that.  Is that just common wisdom
or am I missing a fundamental reason, here?  Or are all the other
constructs strong enough to not requiring plain LoadLoad?  Not really,
since a simpe, non-pointer consumer could still have their flag / data
loads reordered.  Or is it rather because every consumer will eventually
produce data (that should be ordered behind the data read if it were
derived from it though)?

--
Thanks,
  Stephan

Stephan Diestelhorst
Staff Engineer
ARM R&D Systems
+44 (0)1223 405662


-- IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium.  Thank you.

ARM Limited, Registered office 110 Fulbourn Road, Cambridge CB1 9NJ, Registered in England & Wales, Company No:  2557590
ARM Holdings plc, Registered office 110 Fulbourn Road, Cambridge CB1 9NJ, Registered in England & Wales, Company No:  2548782