1.1.6. ALM Output
The LUT, adder, or register output can drive the ALM outputs. The LUT or adder can drive one output while the register drives another output.
Register packing improves device utilization by allowing unrelated register and combinational logic to be packed into a single ALM. Another mechanism to improve fitting is to allow the register output to feed back into the LUT of the same ALM so that the register is packed with its own fan-out LUT. The ALM can also drive out registered and unregistered versions of the LUT or adder output.