The Pope has regularly spoken out against them.
"You know how walls finish up. All walls collapse -- today, tomorrow or after 100 years. Walls are not the solution. The problem remains, but with more hate."
"People and institutions who close doors to them (migrants) should seek forgiveness from God"
"Every Catholic parish, every religious community, every monastery, every sanctuary in Europe should accommodate one family, beginning with my diocese of Rome. [In wake of the] tragedy of tens of thousands of refugees that flee death in conflict and hunger and are on a journey of hope, the Gospel calls us to be close to the smallest and to those who have been abandoned"
I think his position has been clear and consistent with Christian values. As you'd expect from him really.