PTR-PLUS merge into the mainline

[Andrew Pinski]

On 6/29/07, Roman Zippel <zippel@linux-m68k.org> wrote:
> Hi,
>
> On Thu, 28 Jun 2007, Andrew_Pinski@PlayStation.Sony.Com wrote:
>
> > Roman Zippel <zippel@linux-m68k.org> 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@suse.de>

        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