&gt; Sony [...] as they were developing the toolchain for the PS4 [...] couldn&#x27;t add their contributions into the LLVM toolchain<p>Why is that?  Do you have something I can read about this?<p>This is the only thing I can find on the topic, and it mentions upstreaming by default after some time (&quot;living on trunk&quot;): <a href="http:&#x2F;&#x2F;llvm.org&#x2F;devmtg&#x2F;2013-11&#x2F;slides&#x2F;Robinson-PS4Toolchain.pdf" rel="nofollow">http:&#x2F;&#x2F;llvm.org&#x2F;devmtg&#x2F;2013-11&#x2F;slides&#x2F;Robinson-PS4Toolchain....</a>