More on memory barriers

David Holmes david.holmes at
Thu Sep 18 02:42:25 UTC 2014

On 17/09/2014 9:16 PM, Doug Lea wrote:
> On 09/17/2014 06:31 AM, Andrew Haley wrote:
>> On 09/16/2014 08:40 AM, Andrew Haley wrote:
>>> On 15/09/14 17:20, Vitaly Davidovich wrote:
>>>> Looking at hg history, MemBarStoreStore was added a few years ago,
>>>> whereas
>>>> the code in question is much older.  The comments in the changelist
>>>> adding
>>>> MemBarStoreStore seem to indicate it was done to address a specific
>>>> issue,
>>>> and my guess is that it wasn't "retrofitted" into all possible places.
>>> That sounds plausible.  I'll change this to a StoreStore in the AArch64
>>> port and do some testing.
>> Bah, that doesn't work.  Escape analysis assumes that a StoreStore
>> is only used in certain contexts.  Back to the drawing board.
> The setup for StoreStore seems suspicious. I believe that this could
> only work in C2 if done in the way I mentioned: StoreStore must be
> handled identically to Release by c2, but possibly more cheaply
> matched. Can StoreStore be reworked as a subtype or property of
> Release?

I'm not a C2 person but I don't understand in what way a storestore can, 
or should, be considered a "subtype" of release ??


> -Doug

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