Re: Incorrect DWARF-2 register numbers on PPC64?

[Alan Modra <amodra@bigpond.net.au>]

On Wed, Jan 07, 2004 at 06:43:10PM +0100, Mark Kettenis wrote:
> If I read your patch correctly, this fixes normal DWARF 2 debugging
> info to use the official System V register numbers, but lets GCC
> continue to use its own numbering for the Call Frame Info (CFI) in
> both the .eh_frame and .debug_frame sections. 

That's correct.  hppa, hppa64, iq2000 and ns32k all do the same.

mips and cris also define DWARF_FRAME_REGNUM, but squinting at the code
leads me to believe they will actually use the same register numbers.

> This won't work for GDB
> since it assumes that CFI uses the same register number encoding as
> all the other DWARF 2 debug information.

Hmm, I can see that a debugger might reasonably expect .debug_frame
to have the same numbers.  When I wrote the patch, I was concentrating
on .eh_frame rather than .debug_frame, but .debug_frame uses the
.eh_frame numbering.  It's a little perplexing that dwarf2out.c does
this, as it means defining DWARF_FRAME_REGNUM to something other
than DBX_REGISTER_NUMBER is useless.  DWARF_FRAME_REGNUM ought to
just effect .eh_frame.  I'm not keen on trying to untangle dwarf2out.c
though..

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre