[llvm] r323297 - Don't assume a null GV is local for ELF and MachO.

[Brooks Moses via llvm-commits]

On Fri, Feb 9, 2018 at 11:10 AM, Rafael Avila de Espindola <
rafael.espindola at gmail.com> wrote:

> Brooks Moses <bmoses at google.com> writes:
> > On Fri, Feb 9, 2018 at 6:54 AM, Rafael Avila de Espindola <
> > rafael.espindola at gmail.com> wrote:
> >> Any news? I would really like to recommit the patch.
> >>
> >> It seems unreasonable to hold back a llvm patch because another software
> >> has an incomplete linker implementation, specially when a patch is
> >> available.
> >
> > Sorry for the delay -- my colleague reports that he's testing this now.
> (I
> > think he was out yesterday.)
>

Update: We've tested this on several machines and it appears to be working.

However, one of my Grub-developer coworkers is concerned that this may not
be the right approach.  I personally think you're right, but I'm not
anywhere near an expert, so I've filed a bug against the Grub project
explaining the issue, so that you and my coworker and the other upstream
Grub people can all get on the same page (whatever page that is) about how
this should work.  The bug is here:
https://savannah.gnu.org/bugs/index.php?53113

If possible, I'd like to wait on re-committing this until we know this
approach is something the Grub developers are happy with (regardless of
when/where/which patch lands), so that we have a path forward that we know
won't get broken by Grub going a different direction.


> > Do you have a reference for the part of the ELF ABI that describes why
> the
> > PLT32 references should be treated as PC32 references here?
>
> It comes from the definition of the plt in the PSABI:
>
> https://github.com/hjl-tools/x86-psABI/wiki/intel386-psABI-1.1.pdf
>
> Since the final function is know, calling the plt is the same is calling
> the final function.
>

Thanks!  I've passed that along in hopes of convincing my coworker that
this doesn't require a full GOT implementation in Grub.  :)

- Brooks
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