Re: Another AIX Bootstrap failure

[David Edelsohn <dje.gcc@gmail.com>]

On Mon, Jun 16, 2014 at 11:44 PM, Jan Hubicka <hubicka@ucw.cz> wrote:

>> The linker is not seeing the local definition of
>> ._ZN14__gnu_parallel9_SettingsC1Ev.  libstdc++ is built with
>> Linux-like semantics, so it allows symbols to be overridden. AIX calls
>> everything through the PLT. But the real definition of the function is
>
> Even static functions?
>
>> not being seen.
>>
>> I'm not exactly sure why inlining changing this and what these extra
>> levels of indirections are trying to accomplish. The visibility of the
>
> To avoid using PLT and GOT when the unit refers to the symbol and we know
> that interposition does not matter.

I am not certain if the linker is creating the PLT stub code because
it wants to allow interpolation or because it cannot see a definition
of the function and wants to allow for some other shared library to
provide the definition at runtime.

> Why branch to a non-global (static) symbol
>   b ._ZN14__gnu_parallel9_SettingsC1Ev.localalias.0
> leads to PLT stub here and why branching to such symbols seems to work otherwise?

Branching to non-global (static) symbol, even an alias, is working
here. The weak function seems to be the problem.

> The failing branch is
>>         b ._ZN14__gnu_parallel9_SettingsC1Ev.localalias.0
> so the call to static construction seems to have happened correctly but we can
> not get right the call from the constructor to static function (that is an alias
> of a global symbol)

The linker appears to not want to resolve the weak function. If I
change ._ZN14__gnu_parallel9_SettingsC1Ev to lglobl, it works. If I
change the static constructor to call the weak function directly,
avoiding the alias, it shows the same failure mode.

I don't know what code generation looked like before.  Was GCC
generating calls to weak functions within the same file?

Thanks, David