Re: [PATCH, ARM] Fix Dwarf register numbering for VFPv3/Neon registers

[Richard Earnshaw <rearnsha at arm dot com>]

On Fri, 2009-11-20 at 19:35 +0000, Julian Brown wrote:
> On Fri, 30 Oct 2009 10:12:46 +0000
> Richard Earnshaw <rearnsha@arm.com> wrote:
> 
> > On Thu, 2009-10-29 at 16:35 +0000, Julian Brown wrote:
> > > +     The recommended encodings for S0-S31 is a DW_OP_bit_piece of
> > > the
> > > +     corresponding D register.  However gdb6.6 does not support
> > > this, so
> > > +     we use the legacy encodings.  We also use these encodings for
> > > D0-D15
> > > +     for compatibility with older debuggers.  */
> > 
> > This comment implies that the problem was probably fixed in gdb-6.7
> > which is now over two years (and three releases ago).  Is the comment
> > wrong, or do we now support this.  Given the status of the VFP support
> > in GDB, I would really expect that someone wanting to debug VFP would
> > need a more recent version of the debugger than 6.6 anyway, so I
> > wouldn't see that as a reason for keeping the old numbering.
> 
> As far as I can tell, current GDB doesn't have any support for
> DW_op_bit_piece either (so writing a specific version number in that
> comment was perhaps a bit optimistic). Using the deprecated numberings
> should work for now, but runs the risk of this issue never being fixed
> properly. Fixing GDB and GCC to use the proper encoding would mean that
> folks couldn't debug GCC-compiled VFPv3 code until they upgraded their
> GDB to one which contained the hypothetical DW_op_bit_piece support
> too.
> 
> So, what's the best way forward?
> 
> Julian

Remove the version information and change the comment to an XXX Fixme
type.

R.