An algorithm based on the Hungarian method for register reduction during complex functional unit allocation

The trends of high-level synthesis are moving from using elementary operations to more complicated operations. These complex operations are implemented by using complicated functional units. Most complex components only have single data I/O ports (buses) so that memory devices, such as stacks, are inside the components to hold the input operands and results for execution. Traditional register allocation algorithms can not be applied directly because the internal memory devices can used to hold the intermediate values. An algorithm which is based on the Hungarian Method has been developed to minimize the use of registers when complex functional units are used.