[cfe-commits] [patch][pr13124] Use strong symbols for functions that go in a strong vtables

[Rafael Espíndola]

Now with the patch.

On 27 June 2012 13:24, Rafael Espíndola <rafael.espindola at gmail.com> wrote:
> The tests in pr13124 shows a case where both gcc 4.7 and clang produce
> an undefined reference to a destructor that we currently output (in
> another TU) as linkonce_odr.
>
> This works 99.9% of the time because we output a strong vtable that
> references that destructor, preventing any of the existing
> optimizations from dropping it, but there is no guarantee that that
> cannot happen. For example, function merging could merge that
> destructor with another one since they are unnamed_addr.
>
> This also causes problems when globalopt marks linkonce_odr
> unnamed_addr functions hidden and we are using the symbol across
> shared libraries.
>
> The attached patch ensures that we produce a strong symbol for
> functions that go in an strong vtable. This in turn ensure that it is
> safe to output those vtables as available_externally in other TUs (and
> use clang compiled libraries with gcc 4.7 compiled programs).
>
> Cheers,
> Rafael
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