Re: S/390: Default to -fasynchronous-unwind-tables

[Jan Hubicka <jh at suse dot cz>]

> On Fri, Nov 15, 2002 at 06:05:35PM +0100, Ulrich Weigand wrote:
> > Hello,
> > 
> > this switches on the DWARF-2 unwind data for all functions by default.
> > 
> > Thanks to Jan Hubicka for pointing out the correct way to do so.
> > 
> > Bootstrapped/regtested on s390-ibm-linux and s390x-ibm-linux.
> > 
> > (Note: a not-yet-published patch to gdb is necessary to actually exploit
> > the DWARF-2 data for backtraces on s390.)
> 
> Should we be thinking about doing this on more architectures?  It would
> be nice to use this in preference to the terrifying MIPS-specific
> unwinder, for instance...
I think we first need to update GDB part.  As far as I am informed, the
GDB dwarf code needs some massaging to work on other backends.
I would like to see this enabled for i386 and default to
-fomit-frame-pointer too BTW.
> 
> How bad is the space penalty, and is there a way to mark EH tables as
> removable if they're only needed for debugging (vs. for -fexceptions)?
One should also think about stack unwinding needed for other reasons -
for instance garbage collecting.
I think there is some linker feature to throw away eh section when not
needed tought.

Honza
> 
> -- 
> Daniel Jacobowitz
> MontaVista Software                         Debian GNU/Linux Developer