develop a 'customized ld'

[sean yang]

>From: Daniel Jacobowitz <drow@false.org>
>To: seanatpurdue@hotmail.com, 
>binutils@sourceware.org,Simon.Richter@hogyros.de
>Subject: Re: develop a 'customized ld'
>Date: Sat, 10 Sep 2005 13:43:02 -0400
>
>On Sat, Sep 10, 2005 at 10:19:47AM -0700, Ian Lance Taylor wrote:
> > Simon Richter <Simon.Richter@hogyros.de> writes:
> >
> > > sean yang wrote:
> > >
> > > > For example, I want to find the program counter(i.e., the address of 
>the
> > > > instruction) of "call '@foo'" instruction at link time.
> > >
> > > This can be done for assembler code, but obvoisly not for C code as
> > > there is no way to make sure the C compiler will always use the same
> > > instructions. Just declare an assembler label in front of the
> > > instruction of which you want to take the address.
> >
> > You can use a gcc extension creatively to approximate this:
> >
> > void foo ()
> > {
> >  lab:
> >   printf ("%p\n", &&lab);
> > }
>
>But be careful with it - recent versions of GCC are pretty bad about
>preserving the addresses of labels not used for control flow.  I assume
>Ian's example will be OK, but if you don't have a computed goto which
>might target the label, GCC may just put it somewhere else...
Thanks to both of you. This is one conern, the other is I really don't want 
to have extra intruction--if the programming load for modification the 
binutils is not too heavy. Perticularly, I don't want to have printf() in 
the final code. Could u give some more suggestion on this?

Thanks again,
Sean

>
>--
>Daniel Jacobowitz
>CodeSourcery, LLC

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