ipa-visibility TLC 2/n

[Jan Hubicka]

> Honza,
> 
> Thanks for this patch which improves some of the G++ testsuite
> failures, but most of the libstdc++ testsuite continues to fail on
> AIX.

Yep, I am still looking into this.  Just made new alias verifier that
catches quite few nonsenses in how C++ builds thunks and same body
aliases.  I am testing it on PPC now (it takes a while)
> 
> This patch clearly was risky and should have been more thoroughly
> tested on non-GNU/Linux systems. All of these failures make it
> impossible to know if other failures have been introduced into the AIX
> port.
> 
> I will be happy to work with you to debug these failures, but I wish
> to ask that the IPA visibility patch be reverted until AIX testsuite
> results can return to a normal state with the patch applied.

OK, the change does redirecting of functions and variables.  I will try
to figure out which of those two changes actually breaks AIX and disable
it for time being.

We are running into existing problems with aliases (obvoiusly making alias
and redirecting uses to it should not break code). Do we care about aliases
working on release branches? (I can make backporatble patches for those fixes,
but given that no one noitced it so far means that probably no one uses them)

Honza
> 
> Thanks, David