[PATCH] Add new debug kind LocTrackingOnly.

[Eric Christopher]

>> Hm, perhaps. I would be penalizing -Rpass, however. But I guess it doesn't
>> matter much. I'll amend the documentation to state that -gcolumn-inf is
>> needed with -Rpass.
>
> Well it's not worse - currently -Rpass doesn't enable debug info at
> all , but I suppose it at least suggests the user enable both -gmlt
> and -gcolumn-info. But I assume if they enabled -g(mlt or otherwise)
> they wouldn't be told they should use -gcolumn-info.
>
> So, committing this patch without the column info would be sort of a
> regression, but sort of not... Given this is a developer feature only,
> I'm OK with it being a little rough around the edges. Up to you
> though, we can discuss the issues with -gcolumn-info and -Rpass in
> this review if you prefer. Just figured it'd be better to separate
> them if practical.
>

Separately from the rest of the patch we might want to look into
turning column info back on for -gmlt in particular. It's the use case
for the sanitizers etc and so having slightly more accurate back
traces is a fairly good thing there. Especially as we get the size of
-gmlt down we can look into using that room for things that are
explicitly useful.

Thoughts?


-eric