8-byte register values on a 32-bit machine

Daniel Jacobowitz drow@mvista.com
Mon Mar 3 04:50:00 GMT 2003


On Sun, Mar 02, 2003 at 10:35:01AM +0100, Stephane Carrez wrote:
> Hi!
> 
> Michael Elizabeth Chastain wrote:
> 
> >[...]
> >Anyways, I think there are two problems here:
> >
> >(1) dwarf2_evaluate_loc_desc is getting called with ctx->in_reg=true
> >    and size=8.  I need to provide an actual test executable to show
> >    this happening.  When this happens, dwarf2_evaluate_loc_desc just
> >    reads *1* register.  This is definitely wrong (if my description
> >    of gdb's behavior is accurate).
> >
> 
> 
> clap! clap! clap!
> 
> FYI, I have this problem too with HC11 and it is *critical* for me as
> this platform being a 16-bit register target, it uses multiple registers
> quite intensively (up to 4 for long long).  It was working very very well 
> before...

OK, so we need to do something about this before the next release. 
It's a problem I hadn't anticipated.  I have several ideas on how to
progress, particularly:
  - Making a call to the LOC_COMPUTED functions return a LOC_REGISTER
so that the logic in read_var_value can go back to handling this case.
  - Implement the get-next-register mechanism that Mark K. designed.

Hmm, for the former I'm not sure I know what I want it to look like
yet; but some logic definitely needs to be pushed higher than it is
(i.e. out of the evaluator).

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer



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