You're right - BB arguments are more general than LLVM-style PHI nodes. They are a strict superset, but are otherwise isomorphic for the cases they both support.
The talk we gave at CGO yesterday includes a few slides talking about the tradeoffs here. Those slides should be public in the next day or three.
The talk we gave at CGO yesterday includes a few slides talking about the tradeoffs here. Those slides should be public in the next day or three.