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

Subject: Re: [boost] [release/atomic] request permission to merge 86144
From: Tim Blechmann (tim_at_[hidden])
Date: 2013-10-14 18:16:51

>> 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.

ccing gavin, who provided the patch and asked me to merge it.