// the current phi is
		//    v = φ(v0, v1, ..., u, ..., vk)
		// then the merged phi is
		//    v = φ(v0, v1, ..., u0, ..., vk, u1, ..., un)
		v.SetArg(i, u.Args[0])
		v.AddArgs(u.Args[1:]...)
	} else {
		// If the original block contained u = φ(u0, u1, ..., un) and
		// the current phi is
		//    v = φ(v0, v1, ...,  vi, ..., vk)
		// i.e. it does not use a value from the predecessor block,