In FPGAs the routing resources are fixed and their usage is constrained by the locationof antifuses. In addition, the antifuses affect the layout performance significantly,depending on the technology. Hence, simplistic placement level assumptions turn out tobe grossly inadequate in predicting the timing and wirability behavior of a layout.There is a need, therefore, for a layout technique which changes the layout at placementlevel based on accurate post-layout timing analysis and net wirability. In this paper weconsider such a wirability and performance driven layout flow for row-based FPGAs.Timing information from a post-layout timing analyzer and wirability informationfrom global and channel routers are used by an incremental placer to effectively perturbthe placement. A large improvement (up to 29%) in timing, has been obtained(compared to non-iterative FPGA layout) for a set of industrial designs and benchmarkexamples.
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