I try and do my best to help out with testing Gentoo on my range of different machines. One of them is an Intel Itanium 2.
I had been having issues building glibc. A friendly user on the IRC channel debugged this. He wrote a blog post about it that is well worth the read, even if you don't use IA64 machines.
This is the GCC fix
Thanks slyfox/trofi for such a detailed write up. This has helped me.