[patch] Refactor linkage computation in CGObjCMac.cpp

[Rafael Espíndola]

ping

On 20 February 2014 17:08, Rafael Espíndola <rafael.espindola at gmail.com> wrote:
> Hi John,
>
> Back in http://llvm.org/bugs/show_bug.cgi?id=3267#c4 when I first
> added private linkage Chris noted that "Darwin has a similar class of
> thing and a lot of ObjC metadata has this sort of symbol. We're
> hacking around it by setting DECL_ASSEMBLER_NAME to include the prefix
> for darwin, which is ugly."
>
> A similar hack still lives in clang today. Now that PR18743 has been
> fixed, I was curious to see if that could be fixed too. It looks like
> it can, but the logic for computing the linkage is a bit convoluted,
> so I decided to fix that first.
>
> Currently the globals are created with the wrong linkage and patched
> afterwards. From the comments it looks like something would complain
> about having an internal GV with no initializer. At least in clang the
> verifier will only run way after we set the initializer, so that is
> not a problem.
>
> The attached patch should be a nop. It just figures out the linkage
> earlier and converts the old calls to setLinkage to asserts. The only
> case where that is not possible is when we first see a weak import
> that is then implemented. In that case we have to change the linkage,
> but that is the only setLinkage left.
>
> As an additional test I have compiled chromium with a patched clang
> and used it to write this email :-)
>
> Cheers,
> Rafael