Re: [boost] [release/atomic] request permission to merge 86144

Subject: Re: [boost] [release/atomic] request permission to merge 86144
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2013-10-14 10:07:59

On Monday 14 October 2013 15:49:46 Tim Blechmann wrote:
> i'd like to merge r86144 into release. it is not exactly a bugfix, but
> it enables double-width cas support for msvc, which is rather important
> for many lock-free algorithms to be lockfree with this toolchain
> (including some configurations of stack/queue of boost.lockfree).

I don't think the commit is correct.

1. 64-bit CAS for 32-bit x86 was already supported before. It is controlled by 
the BOOST_ATOMIC_X86_HAS_CMPXCHG8B macro, which is automatically defined when 
the compiler targets Pentium or later (may need to be enabled by a compiler 
switch).

2. Your change modifies 64-bit branch, which always have 64-bit atomic ops 
available (i.e. CAS-based path is not needed). This branch is not used by 32-
bit targets.