Re: [rfa/6.0] Fix a thinko in dwarf2loc

Elena Zannoni
2003-09-09T21:18:27Z

Daniel Jacobowitz writes:
> On Sun, Aug 24, 2003 at 12:48:55PM -0400, Daniel Jacobowitz wrote:
> > On Sun, Aug 17, 2003 at 04:58:22PM -0400, Daniel Jacobowitz wrote:
> > > On Fri, Aug 01, 2003 at 03:32:45PM -0400, Daniel Jacobowitz wrote:
> > > > Any variable with DW_OP_reg* requires a frame to read it - what
> > > > symbol_read_needs_frame () really means is "is this variable meaningful when
> > > > the program is not running".
> > > >
> > > > This would show up in the testsuite, but GCC doesn't tend to put locals in
> > > > registers without optimization or register keywords everywhere. Symptom is
> > > > that a watchpoint was not deleted when we left its scope, since we thought
> > > > it was global.
> > > >
> > > > OK?
> > >
> > > Ping...
> > >
> > > [Does dwarf2loc fall under the maintenance umbrella of the dwarf2
> > > reader?]
> >
> > Ping? I would like to fix this bug for 6.0.
>
> Jim, Elena? I hit this bug again in testing the
> deprecated_safe_get_selected_frame () patch.
>
> > > > 2003-08-01 Daniel Jacobowitz <drow@mvista.com>
> > > >
> > > > * dwarf2loc.c (dwarf2_loc_desc_needs_frame): Variables in a
> > > > register do need a frame.
> > > >
> > > > --- gdb-5.3.20030801/gdb/dwarf2loc.c.orig 2003-08-01 14:58:57.000000000 -0400
> > > > +++ gdb-5.3.20030801/gdb/dwarf2loc.c 2003-08-01 15:00:05.000000000 -0400
> > > > @@ -318,7 +318,7 @@ dwarf2_loc_desc_needs_frame (unsigned ch
> > > >
> > > > free_dwarf_expr_context (ctx);
> > > >
> > > > - return baton.needs_frame;
> > > > + return baton.needs_frame || ctx->in_reg;
> > > > }
> > > >

Hmmm, the ctx just got freed, you cannot dereference it. Need to use a
local variable. What you are really saying here is that the
needs_frame variable is not sufficient to describe what's needed. Can
the case be added, so that needs_frame becomes OK? Proabably you
need another need_frame_* function.

elena

> > > > static void
> > > >
> > > >
>
> --
> Daniel Jacobowitz
> MontaVista Software Debian GNU/Linux Developer