body, outside of returns. Also adjusts the callers of said functions.

      For example, the code
        func.func @f(%arg0, %arg1) {
          SomeOpThatUsesArg0(%arg0)
          return %arg0
        }
        ...
        call @x_1(x, y)

      would be transformed into
        func.func @f(%arg0) {
          return %arg0
        }