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Re: infinite loop processing siblings - dwarf2reader - dwarf 3 debug
On Mon, Oct 26, 2009 at 03:13:41PM -0600, Tom Tromey wrote:
> >>>>> "Jason" == Jason Richards <jsn.richards@gmail.com> writes:
>
> Jason> I encountered a problem where GDB gets stuck in an infinite loop
> Jason> processing dwarf 3 debug information. Turns out the producer has
> Jason> placed a sibling attribute in a die in a comp unit which
> Jason> references a previous die in the comp unit.
>
> This does not sound like valid DWARF to me. Section 1.9 makes it sound
> as though the only valid value is the DIE's next sibling.
That's right. What is this producer?
> Jason> It seams to me the appropriate fix for this problem is to change
> Jason> "locate_pdi_sibling" to first return the location past the
> Jason> children, before returning sibling information, which fixes this
> Jason> particular problem.
>
> Jason> Is there something I am not thinking about?
>
> I don't know why the code is the way it is; I assume for performance but
> I have not looked into it at all.
You are correct. This optimization is the point of DW_AT_sibling, in
fact.
--
Daniel Jacobowitz
CodeSourcery