ABSTRACT
This chapter introduces topics relevant to top-down partitioning-based placement that must be addressed by all modern mincut placers. Specifically these include terminal propagation, bipartitioning versus multiway partitioning, cutline selection, and whitespace allocation. The chapter describes several techniques that are improvements to the to the mincut partitioning-based framework presented. Proper handling of terminals is essential to the success of top-down placement approaches. A compromise is possible by using an extended formulation of partitioning with fixed terminals, where the terminals are considered to be fixed in one or more partitions, and assigned zero areas. Usually cutlines are aligned to placement row and site boundaries to ease the assignment of standard-cells to rows near the end of global placement. To achieve a nonuniform allocation of whitespace, free cells are added to the design that is placed using uniform whitespace allocation.
