[Dwarf-Discuss] how to find local variable stored in register

Frank Ch. Eigler fche@redhat.com
Tue Feb 5 21:50:17 GMT 2008

Hi -

On Tue, Feb 05, 2008 at 09:18:34PM +0000, Robinson, Paul T (NonStop) wrote:

> Pedantic super-precision would have a serious cost in terms of the
> size of the debug info.

Do you have a sense of how much?  My limited experience with recent
advanced gcc options for reaching for more pedantically super-precise
data :-) indicates nothing worrysome in bloat.

> [...]  We do not view it as a goal to make the DWARF 100% precise
> for every single instruction, because our users don't spend a lot of
> time single-stepping at the instruction level.  [...]
> [...] This is an entirely reasonable compromise between accuracy and
> info size, mediated mainly by usefulness.

Well, your compiler always has the option to indicate "don't know"
(gaps in the location list address ranges) rather than give erroneous
data, but I guess that's a quality-of-implementation issue.  We are
finding an increasing number of uses where more accuracy (even with a
possible loss of "precision" - completeness) is necessary.

- FChE

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