Subject: Re: [boost] [atomic] Probable documentation issue: how do weknowatomic is safe and/or efficient?
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2013-12-24 14:24:43
On Tuesday 24 December 2013 17:17:37 John Maddock wrote:
> >> I'm sure the answer to (a) is that it is correct, but I was surprised
> >> that atomic<int> relied on the volatile modifier for thread safe
> >> load/stores on MSVC, I had assumed that something more than that would
> >> have been required, but I know I'm out of date on this stuff!
> > "volatile" was changed in VC++ 8.0 to guarantee acquire/release semantics,
> > then changed back in 2012 to only do so when /volatile:ms is active, which
> > it is by default, except on ARM.
> > http://msdn.microsoft.com/en-us/library/12a04hfd.aspx
> So does this mean that Boost.Atomic is perhaps not safe after all?
No, it's perfectly safe on x86. It is also safe on ARM if /volatile:ms is
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