add vtable relocs for Alpha

[Ian Lance Taylor]

Bo Thorsen <bo@sonofthor.dk> writes:

> On Mon, 19 Feb 2001, Richard Henderson wrote:
> 
> > On Mon, Feb 19, 2001 at 10:41:14AM -0800, Ian Lance Taylor wrote:
> > > > Richard, in which way should it be rewritten?  What should be done in
> > > > general with new targets?
> > >
> > > It should be rewritten to not use relocation entries.  Using
> > > relocation entries requires changes to every single ELF target file.
> > >
> > > Instead, the vtable information should be stored in special sections.
> > > The linker should read the information out of those sections.  This
> > > can be done in generic code in elflink.[ch].
> >
> > Exactly.
> 
> Can you be more specific on what should be done? I'm currently enabling
> C++ support on x86-64 and I would be interested in doing this in a generic
> way, if it's possible. So, if you can explain to me what should be done, I
> can spend some time on it.

I'm not really sure how to be much more specific.

Right now the vtable information is stored in relocation entries.
There are two types: VTINHERIT and VTENTRY.  The entries are created
by the .vtable_inherit and .vtable_entry pseudo-ops in gas.  They are
defined in config/obj-elf.c.  They call fix_new to create the
information.

gas should be changed to instead create a special section or two and
write the information there.

In the linker these relocs are handled by calling
_bfd_elf32_gc_record_vtinherit and _bfd_elf32_gc_record_vtentry.

The linker should be changed to read the special sections and call the
above functions.

Ian