From: Zdenek Dvorak <rakdver@atrey.karlin.mff.cuni.cz>
To: Andrew Pinski <pinskia@physics.uc.edu>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [patch] Partial fix for PR 18048
Date: Sun, 24 Oct 2004 17:57:00 -0000 [thread overview]
Message-ID: <20041024131607.GA14813@atrey.karlin.mff.cuni.cz> (raw)
In-Reply-To: <E15B8822-25BC-11D9-8879-000A95D692F4@physics.uc.edu>
Hello,
> >this patch contains several improvements to ivopts and related
> >optimizations that improve the code produced for mgrid benchmark quite
> >a
> >bit (although even with the patch, ivopts still spoil the code).
> >
> >The improvements are:
> >
> >1) Ivopts produce expressions like
> >
> > *(&a[start] + 8 * index)
> >
> > and believe that the memory access created for it will include the
> > multiplication by 8. This fails if there are several similar
> > accesses, since dom will CSE the "8 * index" part (thus adding
> > unnecessary multiplication instruction, and increasing register
> > pressure).
>
> Isn't this already done by fold_stmt?
no, as far as I can tell. The only thing that seems relevant
is maybe_fold_offset_to_array_ref, which however only handles
constant offsets (and from some reason I do not quite understand
these optimizations are not included in fold, so they cannot be used
easily anyway).
Zdenek
next prev parent reply other threads:[~2004-10-24 13:16 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-24 13:16 Zdenek Dvorak
2004-10-24 17:30 ` Andrew Pinski
2004-10-24 17:57 ` Zdenek Dvorak [this message]
2004-10-25 18:15 ` Zack Weinberg
2004-10-25 22:55 ` Zdenek Dvorak
2004-10-25 23:01 ` Zack Weinberg
2004-10-25 23:02 ` Zdenek Dvorak
2004-10-25 23:10 ` Zdenek Dvorak
2004-10-27 15:38 ` Zdenek Dvorak
2004-10-27 16:22 ` Andrew Pinski
2004-10-27 16:24 ` Zdenek Dvorak
2004-10-27 17:13 ` Dale Johannesen
2004-10-27 20:31 ` Zdenek Dvorak
2004-10-27 19:00 ` Richard Henderson
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