[patch] dwarf2out: Drop the size + performance overhead of DW_AT_sibling

Tristan Gingold gingold@adacore.com
Mon Oct 17 09:44:00 GMT 2011

On Oct 14, 2011, at 4:02 PM, Tom Tromey wrote:

>>>>>> "Tristan" == Tristan Gingold <gingold@adacore.com> writes:
> Tristan> I am not against this patch, my only concern is that there are many
> Tristan> many dwarf consumers and I have no idea how they will react to this
> Tristan> change.
> I tend to think that this is the wrong standard to apply.  In this case
> we would be avoiding a beneficial change -- as measured in both
> performance in a couple of cases, and in size --

I am not against this patch.  I think it would be useful to add an option (-fdwarf-emit-sibling ?) to keep the old behavior.

> for the sake of unknown
> and possibly nonexistent consumers.  I think instead the burden of proof
> should be on those consumers, both to give their evidence and reasoning
> and to engage with GCC.

You know the story here:  they don't use the latest gcc version and start to complain years later.

> Another way to look at it is that there have been many changes to GCC's
> DWARF output in the last few years.  Surely these have broken these
> DWARF consumers more than this change possibly could.

Yes, but there is -gstrict-dwarf to stay compatible with old behavior.


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