Re: PTR-PLUS merge into the mainline

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PTR-PLUS merge into the mainline
\ Andrew_Pinski (16 Jun 2007)
. \ Roman Zippel (29 Jun 2007)
. . \ Andrew_Pinski (29 Jun 2007)
. . . \ Roman Zippel (29 Jun 2007)
. . . . \ Andrew Pinski (29 Jun 2007)
. . . . . \ Roman Zippel (4 Jul 2007)
. . . . . . \ Richard Guenther (5 Jul 2007)
. . . . . . . \ Roman Zippel (5 Jul 2007)
. . . . . . . . \ Richard Guenther (5 Jul 2007)
. . . . . . . . . \ Roman Zippel (5 Jul 2007)
. . . . . . . . . . \ Roman Zippel (5 Jul 2007)
. . . . . . . . . . . \ Richard Guenther (5 Jul 2007)
. . . . . . . . . . . . \ Roman Zippel (5 Jul 2007)
. . . . . . . . . . . . . \ Richard Guenther (5 Jul 2007)
. . . . . . . . . . . . . . \ Roman Zippel (5 Jul 2007)
. . . . . . . . . . . . . . . \ Richard Guenther (5 Jul 2007)
. . . . . . . . . . . . . . . . \ Roman Zippel (5 Jul 2007)
. . . . . . . . . . . . . . . . . \ Richard Guenther (5 Jul 2007)
. . . . . . . . . . . . . . . . . . \ Roman Zippel (5 Jul 2007)
. . . . . . . . . . . . . . . . . . . \ Andrew Pinski (6 Jul 2007)
. . . . . . . . . . . . . . . . . . . \ Richard Guenther (6 Jul 2007)
. . . . . . . . . . . . . . . . . . . . \ Roman Zippel (9 Jul 2007)
. . . . . . . . . . . . . . \ Daniel Berlin (5 Jul 2007)
. . . . . . . . . . . \ Daniel Berlin (5 Jul 2007)

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Subject:	Re: PTR-PLUS merge into the mainline
Group:	Gcc
From:	Andrew Pinski
Date:	29 Jun 2007

On 6/29/07, Roman Zippel <zippel> wrote:
> Hi,
>
> On Thu, 28 Jun 2007, Andrew_Pinski wrote:
>
> > Roman Zippel <zippel> wrote on 06/28/2007 07:54:43 PM:
> >
> > > Hi,
> > > Notice that it generates the (i + 1) * 4 instead of (i * 4) + 4 as with
> > > the other cases. While I tried to debug this I narrowed it down to the
> > > changes in fold_binary(), but I don't really know how to fix this, so
> > > I could use some help here.
> >
> > The main thing is that this is really PR 32120. The problem is only
> > related to the
> > merge because of the way fold_binary works.
>
> I'm not sure that's related, what's happening in my example is that the
> call to fold_plusminus_mult_expr() defeats the optimization attempted in
> pointer_int_sum(). If I use the patch below to restrict the condition, my
> problem is fixed, but PR32120 is unchanged.
> Actually if I compare the final_cleanup dump of PR32120 with the output
> from gcc 4.1, they are basically identical.

The code to fold_binary was added by:
r107218 | rguenth | 2005-11-19 03:29:10 -0800 (Sat, 19 Nov 2005) | 9 lines

2005-11-19 Richard Guenther <rguenther>

PR middle-end/23294
* fold-const.c (fold_plusminus_mult_expr): New function.
(fold_binary): Use to canonicalize PLUS_EXPR and MINUS_EXPR
cases, remove now unnecessary code.

* gcc.dg/tree-ssa/pr23294.c: New testcase.

And it looks like it was doing this transformation this way on purpose.
Now as I mentioned before the way this should be done is using PRE/FRE
to catch the redudent multiplication.

-- Pinski