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Re: [PATCH] Extend dse
- From: Jeffrey Law <law at redhat dot com>
- To: Revital1 Eres <ERES at il dot ibm dot com>
- Cc: Diego Novillo <dnovillo at acm dot org>, Ayal Zaks <ZAKS at il dot ibm dot com>, Dorit Nuzman <DORIT at il dot ibm dot com>, gcc-patches at gcc dot gnu dot org, Victor Kaplansky <VICTORK at il dot ibm dot com>
- Date: Sun, 29 Apr 2007 10:05:29 -0600
- Subject: Re: [PATCH] Extend dse
- References: <OFF285CF7C.53E69B56-ONC22572CC.00211F49-C22572CC.0025DAF7@il.ibm.com>
- Reply-to: law at redhat dot com
On Sun, 2007-04-29 at 09:54 +0300, Revital1 Eres wrote:
>
> gcc-patches-owner@gcc.gnu.org wrote on 26/04/2007 21:44:51:
>
> > Revital1 Eres wrote on 03/23/07 07:34:
> >
> > > I would like to propose the following patch to mainline:
> > >
> > > http://gcc.gnu.org/ml/gcc-patches/2007-03/msg01257.html
> >
> > After you re-work the store-ccp extension that we discussed earlier
> > today, this will probably not be needed. Regular DCE should catch these
> > cases, right?
>
> AFAICT regular DCE nor DSE eliminate cases like the following which this
> patch aims to fix:
>
> S[5].x = 0;
> S[5].y = 0;
>
> S[5].x = x;
> S[5].y = y;
Umm, I would think the existing DSE code can/should eliminate the
dead stores in this case if the aliasing information is accurate
enough to allow disambiguation. What makes you think it can't/won't?
Jeff