Re: PATCH: Fix linkonce support with debug

[Daniel Jacobowitz <drow at mvista dot com>]

On Fri, Jun 13, 2003 at 10:36:22AM -0700, H. J. Lu wrote:
> On Fri, Jun 13, 2003 at 01:30:27PM -0400, Daniel Jacobowitz wrote:
> > On Fri, Jun 13, 2003 at 10:24:50AM -0700, H. J. Lu wrote:
> > > On Fri, Jun 13, 2003 at 02:26:32PM +0930, Alan Modra wrote:
> > > > On Thu, Jun 12, 2003 at 01:01:27PM -0700, H. J. Lu wrote:
> > > > > Alan,
> > > > > 
> > > > > I believe your change mentioned in
> > > > > 
> > > > > http://sources.redhat.com/ml/binutils/2001-09/msg00499.html
> > > > > 
> > > > > breaks linkonce support with debug:
> > > > > 
> > > > > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=7671
> > > > 
> > > > I doubt that changing section ordering has anything to do with this
> > > > problem.  The real problem is that we have debug info for a removed
> > > > section, with relocations that are left dangling.  The debug info
> > > > ought to be removed along with the section, preferably by using
> > > > section groups.
> > > > 
> > > 
> > > This patch seems to work for me. We should try to preserve debug
> > > information discarded by linkonce as much as we can. It may not be
> > > ideal. But it is better than the current one.
> > 
> > No, I believe it is worse.
> > 
> > Consider that you now have multiple sections in .debug_info covering
> > the same PC range - not necessarily all identical.
> 
> That is why I said it was not ideal.
> >
> > Also consider what happens if the multiple copies of the linkonce
> > function are compiled with (say) different optimization levels.  You
> > will have added a lot of line information which is completely bogus.
> > 
> 
> Isn't is completely bogus in this situation today? We are picking

Here at least the bad line number information gets thrown down at PC 0. 
It's still bogus, but on most systems less likely to get in the way.

> one from 2 bad choices. I don't think mine is any worse than the
> current one.

I think it's worse.  It definitely isn't any better.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer