Re: rs6000 / ppc backend in gdb

[Stefan Burström <f94sbu at efd dot lth dot se>]

Hello Daniel

On 2005-08-01, you wrote:

> On Mon, Aug 01, 2005 at 09:32:59PM +0100, Stefan Burström wrote:

> Why can't you use the prologue analyzer in this case?  You don't have
> symbols at the start of functions?  Well, in that case, there's not

Correct. 

> much to be done - what will happen is GDB will find the nearest
> plausible symbol, decide that's the start of the function, and prologue
> analyze from there.  If that is a frameless function, and the function
> you're really in isn't frameless, you'll lose.

However, I don't like to loose :-)

> If you have any bright ideas for handling this without breaking the
> common case, please do share.

Well, for a start, looking at the 'frameless' flag in the frame structure is
a good indication that gdb was able to resolve the frame or not. Currently
all instances where framless = 0 works, so I was thinking of adding
assumptions of the stackframe only when this flag is 1

> Yes, I think that's fairly lame, but I'm not familiar with the PPC
> backend at all.

Yep, indeed it is lame. But indeed it could be helpfull when no prologue is
found. Also, assuming that lr is stored at (sp+4) seems alot less harmfull
than assuming that sp_prev is stored at (sp)  :-)

I'll play around with the ppc backend abit but it would be really helpful if
someone with some knowledge of that backend could email me.

Thanks!

regards,
Stefan Burstrom