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Re: atomic accesses
Martin Jambor wrote:
> On Tue, Mar 04, 2008 at 10:50:17PM +0000, Paul Brook wrote:
>>> AFAIK the only reason we don't break this rule is that doing so would
>>> be grossly inefficient; there's nothing to stop any gcc back-end with
>>> (say) seriously slow DImode writes from using two SImode writes instead.
>> I'm fairly sure ARM already breaks this "rule".
>>
>
> Hm, just out of curiosity, does not Java require 32-bit stores to be
> atomic?
Yes.
> I do not know Java well but I think it does. Do we observe
> this language-specific rule on ARM then?
Yes.
> Do we do it because 32 bit is
> small enough or do we have a mechanism for that?
We do it because 32 bits is small enough. I don't suppose anyone has
gone through any back-end to make sure we don't write 32-bit aligned
stores in two instructions. If we do that, then Java will break, but
I think we have more important things to worry about.
Andrew.