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Date: Wed, 26 Aug 2009 16:37:00 -0000
Message-ID: <84fc9c000908260404w5721de63u30b2dd835a2e21e8@mail.gmail.com>
Subject: Re: Trying to backport alias fix to 4.2
From: Richard Guenther <richard.guenther@gmail.com>
To: Ned Gill <thomas.gill@csr.com>
Cc: gcc@gcc.gnu.org
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On Wed, Aug 26, 2009 at 12:50 PM, Ned Gill<thomas.gill@csr.com> wrote:
>
> FWIW, I'm still looking at this on and off. =A0I beleive the pure functio=
n was
> a red herring, as this example also does the wrong thing:
>
> extern int z;
>
> int foo(int *y)
> {
> =A0 =A0z =3D 1;
> =A0 =A0*y =3D 0;
> =A0 =A0return z; =A0// returns 1, even though y could point to z :(
> }
>
> Not much joy tracking it down as yet. =A0I've attached the alias informat=
ion
> tree dump in case anyone fancies a look. =A0It looks ok to me, but I don't
> really understand it fully.
>
> As a reminder: this bug is fixed from r119502 on trunk. I'd like to fix it
> on 4.2.x.

Sorry, you are hitting some major latent problems there.  The
affected piece got a complete rewrite for 4.3, an isolated fix is likely
not easily possible.  The above problem is that NONLOCAL is
broken - it should have used the SMT for anything instead.

The code in 4.4 is somewhat sane, still corner cases are incorrect
there, hopefully fixed on trunk.

Richard.

>
> Ned.
>
>
> --
>