Cary,

Thank you for your answer!

On 08/13/2015 09:01 PM, Cary Coutant wrote:
> I don't think you really need a new TAG here -- DW_TAG_constant could
> just as easily take DW_AT_GNU_numerator and DW_AT_GNU_denominator as
> an alternative to DW_AT_const_value.

Good idea! I updated the patch accordingly.

> I'm not really sure why DW_AT_small was defined to refer to a
> DW_TAG_constant DIE rather than just providing the constant as the
> attribute value. It would seem more efficient, space-wise, to have a
> DW_AT_scale attribute that would provide a multiplicative scale
> factor, and an optional DW_AT_scale_divisor to provide the denominator
> if necessary.

Agreed.

> Another, perhaps far-fetched, alternative would be to introduce a new
> form that would represent a rational constant as two unsigned LEB128
> values, and allow that form for DW_AT_const_value and/or for
> DW_AT_small.

Indeed, that's an option, but I find it not very convenient: a new form 
would require us to enhance all DWARF reading tools whereas adding new 
tags and attributes is very smooth (not sure this is a good reason, but 
anyway...).

> For now, I'd suggest going with your proposal, except use the existing
> DW_TAG_constant instead of a new TAG. (I.e., just add the two new
> DW_AT_numerator and DW_AT_denominator attributes.)

That's what I did.

>> include/
>>          * dwarf2.def (DW_AT_GNU_bias): New attribute.
>
> This is OK. Looks like a good idea to me.

Great. Thank you again! I comitted the two attached (and updated) 
patches. I will update the corresponding dwarf2out.c changes I submitted 
on July as well.

I also tried to create the new pages on the wiki but it says "You are 
not allowed to edit this page." 
(<https://gcc.gnu.org/wiki/DW_AT_GNU_numerator_denominator?action=edit>, 
I'm logged in as pmderodat). Does anyone know how I should proceed?

-- 
Pierre-Marie de Rodat