Dwarf2 FDE CIE offset

[Daniel Jacobowitz]

On Fri, Dec 07, 2001 at 07:48:11PM +1030, Alan Modra wrote:
> Why is the dwarf2 unwind FDE CIE offset calculated as
> ". - section_start_label" while dwarf2 debug info uses
> "section_start_label - 0"?  In particular, why the sign change?
> 
> I've been implementing section groups for gcc, with the aim of being able
> to discard .eh_frame and .debug_frame info when garbage collecting an
> unused function.  This involves splitting the .eh_frame section into
> multiple sections.  The header stays in .eh_frame, and per function info
> goes into .eh_frame0, .eh_frame1 etc.
> eg.

Have you considered doing this just by editing the eh_frame sections in
the linker?  Yes, I know it's ugly, but most of the machinery is there
after my stabs work; and that should be the only entry in the unwind
table whose value depends on the location within the .eh_frame section,
so you'd just need to be careful to adjust symbols and relocs a little
more correctly than I do for stabs.  A comment was made about the
problems with section proliferation when I suggested using separate
.stabs sections, IIRC.

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer