Re: [boost] [atomic] unconditional cmpxchg8b support

Subject: Re: [boost] [atomic] unconditional cmpxchg8b support
From: Jan Hudec (bulb_at_[hidden])
Date: 2012-10-23 18:14:45

On Wed, Oct 24, 2012 at 00:22:01 +0300, Peter Dimov wrote:
> Steven Watanabe wrote:
> >Seriously, if the compiler is set to compile for
> >an architecture that doesn't support cmpxchg8b,
> >then Boost.Atomic should not generate this instruction.
> 
> It's very, very rare for a user to willingly target 386/486 (these
> processors are all but extinct, not to mention that modern Windows
> versions simply don't run on them.)

They are extinct in desktop. Not necessarily true of embedded systems.

> A GCC target of i386 in practice simply means that a target hasn't
> been set, not that the user explicitly wanted to target i386. Nobody
> wants to target i386.

gcc target i486-linux-gnu means somebody explicitly configured that target.
Since that's how it is configured in both Debian and Ubutnu, it's set in
stone at least until April 2017 (Precise end-of-life).

Note though, that there is no longer any supported version not shipping gcc
with __sync_* support.

-- 
						 Jan 'Bulb' Hudec <bulb_at_[hidden]>