From: Hans-Peter Nilsson <hp@bitrange.com>
To: Andrew MacLeod <amacleod@redhat.com>
Cc: "Joseph S. Myers" <joseph@codesourcery.com>, gcc-patches@gcc.gnu.org
Subject: Re: Implement C11 _Atomic
Date: Thu, 21 Nov 2013 19:24:00 -0000 [thread overview]
Message-ID: <alpine.BSF.2.02.1311211214150.53151@arjuna.pair.com> (raw)
In-Reply-To: <528E2CB6.7020104@redhat.com>
On Thu, 21 Nov 2013, Andrew MacLeod wrote:
> If we add the hook for atomic_align_for_mode, and change the initalizers in
> tree.c, any target which doesnt need/use the hook should be unaffected. So
> everything remains as it is today.
>
> So Putting the hook in shouldn't be an issue. Then you can experiment with it
> on your port and see if you get the desired effect...
>
> I've attached what I think the remaining bits are regarding the alignment.
Right, that's about what I expected. Nice.
Of course, I'd argue that a better default for the atomic
alignment is the max of the default alignment and the natural
alignment, since *you can't have atomic support without extra
machinery for misaligned data* - straddling a page or cache
boundary has dire consequences.
But then the patch would not have the nice property of
"obviously" being a NOP elsewhere. Then again, where it isn't a
NOP, you have breakage anyway. Bah.
> All untested since I wrote it of course :-) In any case, you should just
> need to provide a function to override the alignment for whatever mode(s) you
> need with this...
>
> I can bootstrap and check this on x86 to make sure it doesnt affect anything,
> and you can fool with it and see if you can get your desired results with your
> port.
Thanks! I'll play with it and get back.
brgds, H-P
next prev parent reply other threads:[~2013-11-21 17:21 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-06 0:44 Joseph S. Myers
2013-11-06 22:42 ` Andrew MacLeod
2013-11-07 17:16 ` Uros Bizjak
2013-11-07 17:24 ` Jakub Jelinek
2013-11-07 18:10 ` Uros Bizjak
2013-11-07 18:44 ` Joseph S. Myers
2013-11-07 18:47 ` Uros Bizjak
2013-11-07 18:55 ` Joseph S. Myers
[not found] ` <CAFULd4ZrAEECG+pptH8cRaWznioaM9VXS4TetpEvkWj--n7H1w@mail.gmail.com>
2013-11-07 21:02 ` Joseph S. Myers
2013-11-07 21:08 ` Uros Bizjak
2013-11-07 22:25 ` Uros Bizjak
2013-11-07 22:43 ` Joseph S. Myers
2013-11-08 10:09 ` Uros Bizjak
2013-11-08 13:33 ` Joseph S. Myers
2013-11-21 13:19 ` Hans-Peter Nilsson
2013-11-21 18:03 ` Andrew MacLeod
2013-11-21 18:20 ` Hans-Peter Nilsson
2013-11-21 18:30 ` Andrew MacLeod
2013-11-21 18:49 ` Joseph S. Myers
2013-11-21 18:58 ` Andrew MacLeod
2013-11-21 19:24 ` Hans-Peter Nilsson [this message]
2013-11-22 2:57 ` Hans-Peter Nilsson
2013-11-22 3:03 ` Andrew MacLeod
2013-11-22 3:32 ` Hans-Peter Nilsson
2013-11-22 3:32 ` Joseph S. Myers
2013-11-22 19:12 ` Andrew MacLeod
2013-11-22 20:01 ` Hans-Peter Nilsson
2013-11-08 13:28 Dominique Dhumieres
2013-11-08 13:34 ` Joseph S. Myers
2013-11-08 13:43 ` Dominique Dhumieres
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