PARI/GP Bug report logs - #1237
undefined behaviour in pari_init_parser

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Date: Sat, 28 Jan 2012 21:11:23 +0100
From: Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr>
To: Julian Taylor <jtaylor.debian@googlemail.com>
Cc: 1237@pari.math.u-bordeaux.fr
Subject: Re: Bug#1237: undefined behaviour in pari_init_parser
Message-ID: <20120128201123.GG18200@yellowpig>
References: <4E5E52C5.4050702@googlemail.com>
 <20110901202245.GH17070@yellowpig>
 <4E5FF27B.5080600@googlemail.com>
 <20110902165738.GM17070@yellowpig>
 <20110913144151.GE6199@yellowpig>
 <20120126162508.GA18262@yellowpig>
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On Thu, Jan 26, 2012 at 05:25:08PM +0100, Bill Allombert wrote:
> On Tue, Sep 13, 2011 at 04:41:51PM +0200, Bill Allombert wrote:
> > On Fri, Sep 02, 2011 at 06:57:38PM +0200, Bill Allombert wrote:
> > > On Thu, Sep 01, 2011 at 11:00:43PM +0200, Julian Taylor wrote:
> > > 
> > > Well, you can try the attached patch which work around the compiler issue without
> > > breaking the ABI (tested on sparc).
> > 
> > Hello Julian, 
> > I have uploaded a new Debian package that includes this patch and it was built correctly
> > on all platform, as you can see 
> > <https://buildd.debian.org/status/package.php?p=pari>
> > this includes armel and sparc. 
> > Do you still have issues on armel ?
> > 
> > A technical note: it is possible that stack_init is not standard compliant, but it
> > should be possible to rewrite it in a standard compliant according to
> > <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49330#c8>
> > However gcc-4.6 bug PR49330 is still open so PARI would still be miscompiled.
> 
> Hello Julian,
> 
> Sorry for the long delay,
> 
> I just fixed stack_base to be standard compliant. It seems actually improve things
> with the version of gcc I tried (Debian 4.6.2-12). It did not with older versions.
> 
> This is is revision c3f6b58983. This is backported in PARI 2.5.1 in rev ee8e36931.
> PARI 2.5.1 will be released soon.
> Please check if that also fix things for you.

And now that the code is standard compliant, on sparc-linux, gcc 4.6.2 miscompiles it
by hitting PR49330 while it compiles correctly the non compliant code. Go figure...

Cheers,
Bill.

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