Minimizing wire length in floorplanning

Xiaoping Tang, Ruiqi Tian, Martin D.F. Wong

Research output: Contribution to journalArticlepeer-review


Existing floorplanning algorithms compact blocks to the left and bottom. Although the compaction obtains an optimal area, it may not be good for meeting other objectives such as minimizing the total wire length, which is the first-order objective. It is not known in the literature how to place blocks to obtain an optimal wire length. This paper first shows that the problem can be formulated by linear programming. Thereafter, instead of using the general, but slow, linear programming, this paper proposes an efficient minimum-cost flow-based approach to solve it. This approach guarantees to obtain the minimum total wire length in polynomial time and meanwhile keep the minimum area by distributing white space smarter for a given floorplan topology. This paper also shows that the approach can be easily extended to handle constraints such as fixed frame (fixed area), input-output (IO) pins, preplaced blocks, boundary blocks, range placement, alignment and abutment, rectilinear blocks, soft blocks, one-dimensional cluster placement, and bounded net delay, without loss of optimality. Practically, the algorithm is so efficient that it finishes in less than 0.4 s for all Microelectronics Center of North Carolina (MCNC) benchmarks of block placement. It is also very effective. Experimental results show that the wire length of very compact floorplans can even be improved by 4.2%. Thus, it provides an ideal way for postfloorplanning refinement.

Original languageEnglish (US)
Article number1673748
Pages (from-to)1744-1753
Number of pages10
JournalIEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Issue number9
StatePublished - Sep 2006


  • Block placement
  • Floorplanning
  • Linear programming
  • Minimum-cost flow
  • Sequence pair

ASJC Scopus subject areas

  • Software
  • Computer Graphics and Computer-Aided Design
  • Electrical and Electronic Engineering


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