Applications of Slack Neighborhood Graphs to Timing Driven Optimization Problems in FPGAs

In this paper we examine three different problems related to FPGA placement: timing driven placement of a technology mapped circuit, timing driven reconfiguration for yield enhancement and fault tolerance in FPGAs and timing driven design re-engineering for FPGAs. We show that timing driven relocation which transforms an infeasible placement into a feasible one is a key problem the solution of which will lead to good algorithms for all three of these optimization problems. We introduce the concept of a slack neighborhood graph (SNG) as a general tool for timing driven relocation of modules in an infeasible placement with a bounded increase in critical path delay. The slack neighborhood graph approach provides a unified approach to the solution of the three timing driven optimization problems of interest in this paper.