[LTO][PATCH] Fix long double precision problem

[Doug Kwan (關振德)]

I got no reply from gdb mailing list. Apparently no one care :)

There is another wrinkle. The complex extended float type has the same
issue.  I don't really think it is correct to use DW_AT_bit_size &
DW_AT_bit_offset for this case since the bits are not contiguous.
However, in the name of not complicating things, I prefer using
existing DW_AT_bit_size and DW_AT_bit_offset than adding a new GNU
extension.  I am fine either way. What do you guys think?

-Doug

2007/12/5, Mark Mitchell <mark@codesourcery.com>:
> Doug Kwan (關振德) wrote:
> > The reason why I did the patch that way is to avoid changing the
> > external debugging interface. If we need to serialize precisions, we
> > may not need another GNU dwarf extension.  Currently already gcc emits
> > DW_AT_bit_size and DW_AT_bit_offset pairs for integral types whose
> > precisions are less than their bit width.  We can just add code to
> > handling real scalar types.
>
> Yes, I think you're 100% right.  I've reviewed the DWARF spec and,
> indeed, DW_AT_bit_size/DW_AT_bit_offset are designed for exactly this
> case.  So, we should just arrange to emit that information in dwarf2out.c.
>
> > I am not sure what changes, if any, are required on the client side of
> > the debugging information (e.g. gdb).  I am willing to implement those
> > changes though.
>
> I'm certainly not a GDB expert so I don't know what impact that might
> have either.  It's just making the debug information more complete, so,
> hopefully, it should Just Work, but it could of course also be the case
> that something goes wrong.  Running the GDB testsuite is probably a good
> first cut.  I'd suggest asking on the GDB mailing list.
>
> Thanks,
>
> --
> Mark Mitchell
> CodeSourcery
> mark@codesourcery.com
> (650) 331-3385 x713
>