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SubjectRe: Compilation problem in ndisc.c / 2.5.1-pre2 : possible gcc bug?
On Wed, 28 Nov 2001, Martin Eriksson wrote:

> ----- Original Message -----
> From: "Richard B. Johnson" <root@chaos.analogic.com>
> To: <erik@hensema.net>
> Cc: <linux-kernel@vger.kernel.org>
> Sent: Wednesday, November 28, 2001 8:09 PM
> Subject: Re: Compilation problem in ndisc.c / 2.5.1-pre2 : possible gcc bug?
>
>
> > On 28 Nov 2001, Erik Hensema wrote:
> >
> > >
> > > I've been looking into the compile problems of net/ipv6/ndisc.c in
> > > 2.5.1-pre2 and I found that the asm generated by gcc (2.95.3) is wrong:
> > >
> > > This is a small part of a diff betweem two asm files generated by gcc,
> note
> > > the missing \n's in the wrong code:
> > >
> > > -
> > > - addl 0(%ebp), %edx
> > > - adcl 4(%ebp), %edx
> > > - adcl 8(%ebp), %edx
> > > - adcl 12(%ebp), %edx
> > > - adcl 0(%ecx), %edx
> > > - adcl 4(%ecx), %edx
> > > - adcl 8(%ecx), %edx
> > > - adcl 12(%ecx), %edx
> > > - adcl %edi, %edx
> > > - adcl %eax, %edx
> > > - adcl $0, %edx
> > > -
> > > + addl 0(%ebp), %edxadcl 4(%ebp), %edxadcl 8(%ebp), %edxadcl 12(%ebp),
> %edxadcl 0(%ecx), %edxadcl 4(%ecx), %edxadcl 8(%ecx), %edxadcl 12(%ecx),
> %edxadcl %edi, %edxadcl %eax, %edxadcl $0, %edx
> >
> >
> > This is probably just some loop unrolling, not some as you say "wrong
> > code".
>
> Correct me if I'm wrong, but I don't think "%edxadcl" really assembles....

No, but an edited 'diff' of the assembly output of a 'C' compiler doesn't
really tell much. Note, no line numbers, no clue as to what the diff
was about. The actual defective section of code would be much more
instructive. For instance, is this as a result of an in-line macro
expansion; the result of a <CR><LF> 'dos' file; the true output of
a 'C' file with no __inline__ __asm__?

Cheers,
Dick Johnson

Penguin : Linux version 2.4.1 on an i686 machine (799.53 BogoMips).

I was going to compile a list of innovations that could be
attributed to Microsoft. Once I realized that Ctrl-Alt-Del
was handled in the BIOS, I found that there aren't any.


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