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Re: [3.1.1] Re: GCC performance regression - its memset!
- From: Roger Sayle <roger at eyesopen dot com>
- To: Jan Hubicka <jh at suse dot cz>
- Cc: Richard Henderson <rth at redhat dot com>, <gcc-patches at gcc dot gnu dot org>, <mark at codesourcery dot org>
- Date: Mon, 20 May 2002 09:58:51 -0600 (MDT)
- Subject: Re: [3.1.1] Re: GCC performance regression - its memset!
> Would this patch be OK for 3.1.1 branch? It fixes serious misscompilation.
> Not really regression, since extra switch is needed, but that switch seems
> to be popular.
> >
> > Tue Apr 23 11:48:53 CEST 2002 Jan HUbicka <jh@suse.cz>
> > * i386.c (ix86_expand_clrstr): Fix pasto.
Hi Jan,
You might test whether this patch fixes PR opt/6703. Although the
code in question is dubious (the alignment of the pointer is
incorrect for a void**), the test case produces the correct result
on mainline, but the incorrect result on the 3.1 branch.
Fortunately on x86 lying about alignment just produces slower code,
but on other platforms, we'd end up with misaligned memory accesses.
Given that there haven't been many changes to memset on x86 since
3.1 branched, I was going to check whether this was the patch that
solved the problem on mainline. If it is, then PR opt/6703 would
be a strong argument for adding this patch to the branch.
Roger
--
Roger Sayle, E-mail: roger@eyesopen.com
OpenEye Scientific Software, WWW: http://www.eyesopen.com/
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