Re: location lists

[Michael Eager <eager at eagercon dot com>]

Todd Allen wrote:
> 
>    Right here is where you lose me.  DWARF doesn't describe references to
>    global symbols; it only describe declarations & definitions.  So, how can
>    a debugger know if there is a reference in the current context?  Surely
>    you're not talking about requiring a vendor extension to get this right?
>    Maybe you're talking about deducing the presence of a reference by looking
>    for a replicated global definition (which is problematic for Ada's
>    describe-an-object-once-only approach)?

If there is a reference to a variable in the current context, there must
be a declaration.  

>    I agree that this is a quality of implementation issue, but I don't see
>    how DWARF is enabling a good quality implementation.
> 
>    BTW, have you read the DW_TAG_local_copy idea that's floating around?  It
>    seems to solve this my describing globals as simple location descriptions,
>    and then augmenting that with local information in any compilation that
>    has special case locations for the global.  I believe it would provide all
>    the descriptive functionality that's needed.

It's not needed.  There is no requirement that you describe globals as 
location lists.  As I mentioned previously, this seems to be a rather 
awkward and unrewarding approach to handling globals.

You've identified a problem which (almost) every other debugger solves 
without difficulty, using existing Dwarf 1 or Dwarf 2 (or other
debug format), without requiring extension.

It looks to me that you have fixated on a particular implementation 
which you are finding to be difficult.  Might I suggest that you look 
for a different implementation?   

-- 
Michael Eager	 Eager Consulting     eager@eagercon.com
1960 Park Blvd., Palo Alto, CA 94306  650-325-8077