Re: [testsuite & dwarf2] How to handle store.exp failure on AMD64?

[Daniel Jacobowitz <drow@mvista.com>]

On Thu, Aug 07, 2003 at 10:58:48AM -0400, Andrew Cagney wrote:
> >On Thu, Aug 07, 2003 at 10:49:59AM +0200, Michal Ludvig wrote:
> >
> >>4) let GDB pretend that all registers have the same value unless said 
> >>otherwise later in the .debug_frame and convince GCC to put a note when 
> >>their value is overwritten.
> >>
> >>Opinions?
> >
> >
> >See the archives of this list, from about a month ago.  I discussed
> >this with Richard but never got around to writing a patch.
> 
> And I forgot to commented on the thread also  :-(
> 
> There are several bugs:
> 
> - An architecture should mark a limited set of registers as, for want of 
> a better phrase, `always unwind'.  System registers, for instance, would 
> fall into that category.  No preserve registers, however, are a more 
> interesting problem.
> 
> - GCC should be generate, and GDB should consume, more complete 
> variable location information.  If a variable isn't preserved across a 
> function call then GCC/GDB should report the variable as being unavailable.

I'm not talking about variable location information.  I'm talking about
register unwind information; and Richard's claim that the default
should be unmodified makes sense in the context of unwinding.

Variable locations are a different problem.  A serious one, maybe, but
unrelated.

> - GCC -O0 should should not eliminate variables, and should preserve all 
> variables across function calls.
> 
> Given that is compiled with -O0, I think GCC is failing on count #3 here.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer