[Bug debug/66728] [5/6 Regression] CONST_WIDE_INT causes corrupted DWARF debug info

["rsandifo at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66728

rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2015-07-02
           Assignee|unassigned at gcc dot gnu.org      |rsandifo at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #3 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
(In reply to Ulrich Weigand from comment #1)
> A bit of debugging shows that what's going on here is this:
> 
> add_const_value_attribute is called with the following constant RTL:
> (const_wide_int 0x80000000000000000000000000000000)
>
> The routine then does:
>          add_AT_wide (die, DW_AT_const_value,
>                       std::make_pair (rtl, GET_MODE (rtl)));
> 
> Note that GET_MODE (rtl) is VOIDmode.  This apparently causes creation of a
> wide_int value with precision 0:
> {<wide_int_storage> = {val = {0, -9223372036854775808, 2}, len = 2,
> precision = 0}
> 
> This seems already wrong, but doesn't quite explain the inconsistent output.

Yeah, wide_ints shouldn't have precision 0.  I think the later problems
do follow from that, although like you say there is probably a disconnect
between the way the DIEs are handled as well.