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Re: [PATCH][2/3] Fix PR54733 Optimize endian independent load/store
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: "Thomas Preud'homme" <thomas dot preudhomme at arm dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 2 Apr 2014 10:16:44 +0200
- Subject: Re: [PATCH][2/3] Fix PR54733 Optimize endian independent load/store
- Authentication-results: sourceware.org; auth=none
- References: <000b01cf4e0e$54044b70$fc0ce250$ at arm dot com> <alpine dot DEB dot 2 dot 10 dot 1404020800200 dot 3584 at laptop-mg dot saclay dot inria dot fr> <001301cf4e41$d2a4f320$77eed960$ at arm dot com>
On Wed, Apr 2, 2014 at 9:04 AM, Thomas Preud'homme
<thomas.preudhomme@arm.com> wrote:
>> From: Marc Glisse [mailto:marc.glisse@inria.fr]
>>
>> Uh? It does fold a+1-a for me. What it doesn't do is look through the
>> definition of b in b-a. Richard+GSoC will supposedly soon provide a
>> function that does that.
>
> Oh right, it's a bit more complex here since the array index is converted
> to an offset first. So the operation is more like: ((a+1)*cst) - (a*cst).
> Any chances this might be handled at some point? Note that this might
> not be very frequent so it's not very important for this patch.
"More like" isn't enough to answer this - do you have a testcase? (usually
these end up in undefined-overflow and/or conversion-to-sizetype issues)
Richard.
> Thanks for the comment.
>
> Best regards,
>
> Thomas
>
>