From: Richard Guenther <richard.guenther@gmail.com>
To: Seema Ravandale <ravandaless@gmail.com>
Cc: gcc <gcc@gcc.gnu.org>, gcc-help@gcc.gnu.org
Subject: Re: Pointer analysis in GCC-4.3.0 - Getting spurious pointsTo pair.
Date: Mon, 15 Jun 2009 11:19:00 -0000 [thread overview]
Message-ID: <84fc9c000906150419k2bc168d7rb2aa893c9881f5b1@mail.gmail.com> (raw)
In-Reply-To: <ee5d809b0906150333k1e29e549id859cf265defa176@mail.gmail.com>
On Mon, Jun 15, 2009 at 12:33 PM, Seema Ravandale<ravandaless@gmail.com> wrote:
> Hi.
>
> Gimple code of the program I have tried to get the pointsTo
> information is as follow:
>
> A = 0;
> B = &A;
> C = &B;
> D = &C;
> D.1255 = *D;
> D = (int * * *) D.1255;
>
> The expected pointsTo pairs are,
> B = { A } , A = { }, C = { B }, D.1255 = { B }, D = { B C }
>
> But with GCC-4.3.0, and command line options -fdump-ipa-all
> -funit-at-a-time -fipa-pta, we are getting spurious pointsTo pairs
> as,
> D.1255 = { B A } , D = { B C A }
>
> Is the current analysis Flow-insensitive? Even if It is, the sperious
> information, D -> A should not occur.
> Please, Can someone clarify on this?
IPA-PTA is completely bogus (and its results are unused). Further
GCC 4.3 has a very large number of known oddities with computing
points-to information, GCC 4.4 is a lot better here but only GCC 4.5
has fixes for all (known) bugs.
Richard.
> - Seema
>
prev parent reply other threads:[~2009-06-15 11:19 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <ee5d809b0905270045u4775e419q3da30a3e3b8157e8@mail.gmail.com>
2009-06-15 10:33 ` Seema Ravandale
2009-06-15 11:19 ` Richard Guenther [this message]
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