A method of input/output (I/O) assignment for a circuit design for a programmable logic device (PLD) can include determining I/O types for I/O objects specified by the circuit design, defining a plurality of virtual I/O bank-groups, wherein each virtual I/O bank-group includes at least one virtual I/O bank, and binding I/O objects of the circuit design into I/O groups according to the I/O types. A binary compatibility matrix can be created. The binary compatibility matrix can indicate the compatibility between the virtual I/O bank-groups and the I/O groups based upon the I/O types of I/O objects within each I/O group. A determination can be made as to whether a feasible solution exists for I/O assignment of the I/O objects of the circuit design according to a plurality of constraints and the binary compatibility matrix.