[Bug c++/66487] [6 Regression] Firefox segfault with LTO enabled

["marxin at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66487

--- Comment #17 from Martin LiÅka <marxin at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #15)
> (In reply to Jan Hubicka from comment #13)
> > Author: hubicka
> > Date: Wed Jan 13 23:47:45 2016
> > New Revision: 232356
> > 
> > URL: https://gcc.gnu.org/viewcvs?rev=232356&root=gcc&view=rev
> > Log:
> > 
> > 	PR ipa/66487
> > 	* ipa-polymorphic-call.c (inlined_polymorphic_ctor_dtor_block_p):
> > 	use block_ultimate_origin
> > 	(noncall-stmt_may_be_vtbl_ptr_store): Likewise.
> > 
> > Modified:
> >     trunk/gcc/ChangeLog
> >     trunk/gcc/ipa-polymorphic-call.c
> 
> Has this commit fixed the remaining issues?

There's still a remaining issue that is caused by -flifetime-dse that is
*probably* caused by an undefined behavior in Firefox. I've been working on
reduction of the issue. As shown it's caused by a store to a memory that is
clobbered by constructor. Trevor is also focused on the issue, hope we'll hunt
the problem very soon.

Martin