[Dwarf-Discuss] Vendor extensions in .debug_macinfo

[Mark Wielaard]

On Wed, 2011-07-20 at 20:00 +0200, Jakub Jelinek wrote:
> On Wed, Jul 20, 2011 at 10:16:10AM -0700, Michael Eager wrote:
> > but wait until the DWARF committee has had an
> > opportunity to review the proposal and incorporate it into a future version
> > of DWARF.  Should you discover a need for an additional opcode, simply add
> > it to the implementation.
> 
> I'm afraid we don't want to wait a few years for DWARF5 though, we need
> this right now, which is why if DWARF committee preference is a new section,
> I think we should introduce .debug_gnu_macro section and keep it as whole
> as a GNU extension and propose .debug_macro section with the same content
> for DWARF5.  Then, if DWARF5 uses the same format, perfect, if it uses a
> different one, the consumers could just choose to support both formats or
> something and GCC as a producer would phase the GNU extension format out.

Since there is a version field, maybe we could make use of that. So the
preliminary GNU vendor implementation of the .debug_macro section would
use version 1. When DWARF5 is officially published we can check whether
it still matches the preliminary implementation. If it does, the
standard just blesses version 1 as the official version, if not it
starts at 2 (or maybe 5 to match up with the spec number) so consumers
know whether they are dealing with the preliminary implementation or the
"officially blessed" spec compliant version.

Cheers,

Mark