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Re: Optimization of conditional access to globals: thread-unsafe?

From: Jason Merrill <jason at redhat dot com>
To: Ian Lance Taylor <iant at google dot com>
Cc: Diego Novillo <dnovillo at google dot com>, Michael Matz <matz at suse dot de>, gcc at gcc dot gnu dot org, gcc-patches at gcc dot gnu dot org
Date: Wed, 31 Oct 2007 16:40:22 -0400
Subject: Re: Optimization of conditional access to globals: thread-unsafe?
Newsgroups: gmane.comp.gcc.devel, gmane.comp.gcc.patches
References: <e2e108260710260541n61462585u99de9bc0617720f4@mail.gmail.com> <e2e108260710260620k2a2e21b3t1d6c052f14d36094@mail.gmail.com> <20071026143334.GA5041@moonlight.home> <m38x5pj3ig.fsf@localhost.localdomain> <20071026155101.GB5041@moonlight.home> <016201c817e9$5454edd0$2e08a8c0@CAM.ARTIMI.COM> <20071026161739.GC5041@moonlight.home> <Pine.LNX.4.64.0710261836440.23011@wotan.suse.de> <m33avxfu2i.fsf@localhost.localdomain> <b798aad50710261430m62354e98r85d7ba4839443d21@mail.gmail.com> <m3d4v1ecxa.fsf@localhost.localdomain>

Ian Lance Taylor wrote:

It appears that the draft C++0x memory model prohibits speculative
stores.

Therefore I now think we should aim toward prohibiting them
unconditionally.

I agree, or perhaps unless the user specifies a flag like -fthread-unsafe-opts or something.

That memory model is just a draft.

It was voted into the C++ standard working paper at the last meeting. And the C committee has expressed interest in adopting it, or something similar, as well.

Jason

References:
- Re: Optimization of conditional access to globals: thread-unsafe?
  - From: Ian Lance Taylor
- Re: Optimization of conditional access to globals: thread-unsafe?
  - From: Diego Novillo
- Re: Optimization of conditional access to globals: thread-unsafe?
  - From: Ian Lance Taylor

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