restrict on casted pointers

Paulo Matos pmatos@broadcom.com
Thu Aug 29 18:20:00 GMT 2013


> -----Original Message-----
> From: Brian Budge [mailto:brian.budge@gmail.com]
> Sent: 28 August 2013 15:28
> To: Paulo Matos
> Cc: GCC-help
> Subject: Re: restrict on casted pointers
> 
> On Wed, Aug 28, 2013 at 7:12 AM, Paulo Matos <pmatos@broadcom.com> wrote:
> >
> > Now that you mentioned it I did look into bugzilla but didn't find any
> report that matches my concern.  However, there are indeed a few bugs
> regarding restrict.
> > So, given your reply I guess you support the view that this is a gcc missed
> optimization instead of a problem in my interpretation of restrict.
> >
> >
> > Paulo Matos
> >
> 
> Hi Paulo -
> 
> I'm not an expert with restrict, but I am also under the impression
> that this is a missed optimization.  Unless something has changed in
> the standard wrt restrict, it is at least curious that gcc used to (I
> think even up to 4.7) optimize this well.
> 
>   Brian

Yes, I can confirm that GCC 4.5.4 was able to optimize this at cse1. I am going to try to understand why 4.8.1 is not doing this anymore.


-- 
Paulo


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