[Bug ipa/61548] [5 Regression] FAIL: gcc.dg/tls/alias-1.c (internal compiler error)

["tbsaunde+mozilla at tbsaunde dot org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61548

--- Comment #14 from tbsaunde+mozilla at tbsaunde dot org ---
On Mon, Jan 26, 2015 at 03:56:05AM +0000, hubicka at ucw dot cz wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61548
> 
> --- Comment #13 from Jan Hubicka <hubicka at ucw dot cz> ---
> > So, what is here is:
> > emutls calls varpool_node::create_alias(decl("emutls_v.bar"),
> > decl("emutls_v.foo")) which sets alias = true and alias_target =
> > node("emutls_v.foo") on the node for "emutls_v.bar", however it does not set up
> > ref_list.references on node("emutls_v.bar") to point at node("emutls_v.foo").
> > Then during varification we call symtab_node::get_alias_target() which gets the
> > alias from node("emutls_v.bar").ref_list.references but that crashes becauses
> > references doesn't contain an element for the alias target.
> 
> The way to get the references for alias is to call alias->resolve_alias.
> The resolution normally happens at the end of parsing but if someone introduces
> new alias late, he needs to cal the resolve_alias manually.

With that fixed things get a little farther, but there's still a
problem.  symbol_table::remove_unreachable_node () decides to remove one
of the tls aliases.  When varpool_node::remove () is called it first
clears ref_list with a call to symtab_node::unregister () and then calls
varpool_node::cdtor_usable_for_folding () which tries to get the alias
target, and so crashes because ref_list has been cleared.  I guess the
simplest thing is to call cdtor_usable_for_folding earlier, but I don't
know if there's something better.

Trev