Initially, constants are inline, but that does not allow bit-select from verilog constant, an update later used wire to hold constants, but may create multiple wires for the same constants if they are different nodes, this update creates a map to de-duplicate.
Improvement:
Initially, constants are inline, but that does not allow bit-select from verilog constant, an update later used wire to hold constants, but may create multiple wires for the same constants if they are different nodes, this update creates a map to de-duplicate.