[Gc] Should libatomic_ops be inside bdwgc?

Boehm, Hans hans.boehm at hp.com
Wed Aug 10 14:41:44 PDT 2011


Given that libatomic_ops is packaged separately, and seems to be generally available, I don't see a good reason for including it in the gc distribution anymore.  I agree that it seems increasingly strange to include it.  If we don't, we do need to make sure we still have simple build directions for Windows and MacOS etc., e.g. "plug the libatomic_ops tree or a link to it in here".

Hopefully we can arrange to make bdwgc buildable in single-threaded mode without libatomic_ops?  That's been a goal, but I'm not sure it's currently true.

A big part of my motivation in combining them was not to have to maintain two projects, admittedly a dubious argument.

The libatomic_ops API should be stable at this point.  I would discourage major changes, since I think it's obsoleted by C++0x and C1x atomics, which can be viewed as another, much more careful, iteration on libatomic_ops.

In the slightly longer term, bdwgc should also work with C++0x/C1x atomics instead of libatomic_ops.  In the even longer term, we should phase out libatomic_ops.  In the short term, we have too few implementations of the C++0x atomics, and they may still be too immature.

Hans

> -----Original Message-----
> From: gc-bounces at linux.hpl.hp.com [mailto:gc-bounces at linux.hpl.hp.com]
> On Behalf Of Petter Urkedal
> Sent: Wednesday, August 10, 2011 10:52 AM
> To: gc at linux.hpl.hp.com
> Subject: Re: [Gc] Should libatomic_ops be inside bdwgc?
> 
> On 2011-08-10, Ivan Maidanski wrote:
> > Hi Hans and Petter,
> >
> > I have moved libatomic_ops out of bdwgc repo recently.
> > So, if you want to compile bdwgc, you need to have libatomic_ops repo
> inside bdwgc's one.
> > The question is for the future - whether to have libatomic_ops in
> bdwgc release tar-ball or not?
> 
> (For what it's worth, Fedora, Red Hat, Ubuntu and Gentoo ship
> libatomic_ops as a separate package (-devel only).  Is the API
> reasonably stable and independent of libgc?  Does it make sense to have
> a different release schedule for the two?)
> 
> > Hans -
> > What do you think which distribution variant should be best (at least
> for gc72)?
> > In other words, do we still need "EXTRA_DIST += libatomic_ops"?
> > I see only that we shouldn't disable bdwgc configure & make with no
> libatomic_ops installation.
> >
> > Petter -
> > 1. Based on the answer from Hans, could you prepare the relevant
> patch for the scripts (including any other things you think need
> adjusting, if any)? Thanks.
> 
> Sure.
> 
> > 2. The problem really in libatomic_ops itself (that is, I did "make
> distcheck" in it with the same result).
> 
> Just sent you a pull request for this.
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