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Re: [PATCH] Fix memset recognition, paper over PR53346
- From: Andi Kleen <andi at firstfloor dot org>
- To: Richard Guenther <rguenther at suse dot de>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Fri, 18 May 2012 09:38:54 -0700
- Subject: Re: [PATCH] Fix memset recognition, paper over PR53346
- References: <Pine.LNX.4.64.1205181341410.5860@jbgna.fhfr.qr>
Richard Guenther <rguenther@suse.de> writes:
> In PR53346 we vectorize a simple memset loop very inefficiently.
> But of course we should have detected this and transformed the
> loop into a memset! Seems like we only do that if the original
> loop does sth else than memset as well.
Is there a way to turn this off?
I know code written in the past who explicitely wrote memset as a loop
because it couldn't deal with the optimizations optimized memsets do
(like reordering or changing access granuality.
One example is clearing something in memory mapped hardware registers.
It would be good at least if this was not done for volatile.
-Andi
--
ak@linux.intel.com -- Speaking for myself only