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Subject: Re: [OMPI devel] Collective communications may be abend when it use over 2GiB buffer
From: N.M. Maclaren (nmm1_at_[hidden])
Date: 2012-03-05 18:27:50

On Mar 5 2012, George Bosilca wrote:
> I gave it a try (r26103). It was messy, and I hope I got it right. Let's
> soak it for few days with our nightly testing to see how it behave.

That'll at least check that it's not totally broken. The killer about
such wording is that you cannot guarantee exactly how a new vendor will
interpret it. That caused a LOT of trouble with C90 and to some extent
with C99. Currently compilers are following the path of doing less and
less optimisation, rather than more (which was happening then), which
reduces the chances of problems.

I think the chances of any new standard not honouring casts in such
expressions is very low, but I didn't expect the breakages in C99.
I didn't expect that WG14 would completely change their interpretation
of the same wording in a decade, either. As far as I know, C11 hasn't
broken anything in this area (though it has in others), but I haven't
looked at it in detail.

Nick Maclaren.