From: Andrew MacLeod <amacleod@redhat.com>
To: gcc@gcc.gnu.org
Cc: Marc Glisse <marc.glisse@inria.fr>,
Lawrence Crowl <crowl@google.com>,
Benjamin Kosnik <bkoz@redhat.com>,
Richard Henderson <rth@redhat.com>,
Aldy Hernandez <aldyh@redhat.com>
Subject: Re: C++11 atomic library notes
Date: Sun, 02 Oct 2011 13:56:00 -0000 [thread overview]
Message-ID: <4E886D7D.9040905@redhat.com> (raw)
In-Reply-To: <alpine.DEB.2.02.1110021021570.4182@laptop-mg.saclay.inria.fr>
> On Sat, 1 Oct 2011, Andrew MacLeod wrote:
>
>>
>
> Ah ok, I had understood:
> * if __atomic_store_8 is inlined on line 18, it should also be inlined
> on line 42
>
> when instead it is:
> * we can't have a locked addition and a lock-free subtraction (hence
> the __atomic_is_lock_free which only takes a size as argument)
>
> Makes perfect sense, thank you for the precision.
I Added another line in the document to clarify this, thanks.
>
> By the way, does it make sense to work atomically on a 16 byte object,
> and also work atomically on its first 8 bytes, thus potentially
> requiring __atomic_is_lock_free not to depend on the size?
>
not really... working on the first 8 bytes of the 16 byte atomic object
'breaks' the atomicity of the 16 byte object. Volatility of the object
is the only thing that *may* impact this, AFAICT.
Andrew
next prev parent reply other threads:[~2011-10-02 13:56 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4E862864.2010607@redhat.com>
2011-10-01 6:56 ` Marc Glisse
2011-10-01 23:12 ` Andrew MacLeod
2011-10-02 8:40 ` Marc Glisse
2011-10-02 13:56 ` Andrew MacLeod [this message]
2011-10-03 17:31 ` Richard Henderson
2011-10-03 17:54 ` Andrew MacLeod
2011-10-03 18:10 ` Richard Henderson
2011-10-03 19:52 ` Joseph S. Myers
2011-10-05 7:26 ` Jeffrey Yasskin
2011-10-05 18:58 ` Andrew MacLeod
2011-10-05 19:07 ` Jeffrey Yasskin
2011-10-05 20:12 ` Andrew MacLeod
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