Comment # 39 on bug 90887 from Ilia Mirkin

I pushed the following after some light testing:

commit a072ef8748a65d286e9b542bb9ea6e020fdcc7f8
Author: Ilia Mirkin <imirkin@alum.mit.edu>
Date:   Thu Sep 10 01:54:30 2015 -0400

    nv50/ir: make edge splitting fix up phi node sources

But it's not the final word on this stuff... as Béla mentioned in comment 13,
some games aren't completely fixed by this. I have some Hearthstone traces
(from bug #75776) which still have minor visual artifacts. Further, they are
fixed by splitting more edges. [I made the condition only look at
p->cfg.outgoingCount() > 1, which includes a whole lot more than critical
edges. This is clearly wrong, but... gives some ideas.]