Re: rs6000 / ppc backend in gdb

["Stefan Burström" <f94sbu@efd.lth.se>]

Hello Daniel

On 2005-08-01, you wrote:

> On Sun, Jul 31, 2005 at 11:02:36PM +0100, Stefan Burström wrote:
>
> No, absolutely they aren't!  We've learned, over years of debugging
> people's real code, that trusting the architecture defined stack layout

Well, if you don't have any debugging info available then?

> is not a good choice.  For instance, on x86 -fomit-frame-pointer is
> popular to free up an additional register.

Well, I see a lot of problems on architectures where you cannot determine
the layout of the stackframe. But on those architectures you are completely
screwed anyway without debug info

> You weren't very specific about what versions you were testing, but on
> x86 you've probably got DWARF2 CFI available, which allows reliable

Well, the problem is not when debug info is available. The problem is if the
stack chain goes through the OS where no debug info at all is available. 

I suppose I am pretty much on my own if I want to get this functionality
into GDB?

One interesting thing about all this is that even if the PPC backend tries
to be really nice and look at the prologue to determine various aspects of
the frame, it still assumes that the previous sp is saved where the current
sp points.

regards,
Stefan Burstrom