Member predicate PhiNode::hasInputFromBlock

Holds if the node at index i in bb is a last reference to SSA definition def of sv. The reference is last because it can reach this phi node, without passing through another read or write.

The path from node i in bb to this phi node goes via basic block input, which is either a predecessor of the basic block of this phi node, or input = bb in case this phi node occurs in basic block bb.