I don't think this is true - on Xilinx, you can coax a DSP48 macro into implementing a barrel shifter, but the underlying primitive is a multiplier and not a barrel shifter.
Unlike adders, a barrel shifter does not generalize well enough to be implemented as a hard block in its own right.
Unlike adders, a barrel shifter does not generalize well enough to be implemented as a hard block in its own right.