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37th Conference on Design Automation (DAC'00)
Can Recursive Bisection Alone Produce Routable Placements?
Los Angeles, CA
June 05-June 09
ISBN: 1-58113-1897-9
Igor L. Markov, UCLA Computer Science Dept., Los Angeles, CA
Andrew B. Kahng, UCLA Computer Science Dept., Los Angeles, CA
Andrew E. Caldwell, UCLA Computer Science Dept., Los Angeles, CA
This work focuses on congestion-driven placement of standard cells into rows in the fixed-die context. We summarize the state-of-the-art after two decades of research in recursive bisection placement and implement a new placer, called Capo, to empirically study the achievable limits of the approach. From among recently proposed improvements to recursive bisection, Capo incorporates a leading-edge multilevel min-cut partitioner [7], techniques for partitioning with small tolerance [8], optimal min-cut partitioners and end-case min-wirelength placers [5], previously unpublished partitioning tolerance computations, and block splitting heuristics. On the other hand, our "good enough" implementation does not use "overlapping" [17], multi-way partitioners [17, 20], analytical placement, or congestion estimation [24, 35]. In order to run on recent industrial placement instances, Capo must take into account fixed macros, power stripes and rows with different allowed cell orientations. Capo reads industry-standard LEF/DEF, as well as formats of the GSRC bookshelf for VLSI CAD algorithms [6], to enable comparisons on available placement instances in the fixed-die regime. Capo clearly demonstrates that despite a potential mismatch of objectives, improved mincut bisection can still lead to improved placement wirelength and congestion. Our experiments on recent industrial benchmarks fail to give a clear answer to the question in the title of this paper. However, they validate a series of improvements to recursive bisection and point out a need for transparent congestion management techniques that do not worsen the wirelength of already routable placements. Our experimental flow, which validates fixed-die placement results by violation-free detailed auto-routability, provides a new norm for comparison of VLSI placement implementations.
Index Terms:
co-simulation, configurable processor cores, coverage analysis, design verification, system-on-chip, test generation
Igor L. Markov, Andrew B. Kahng, Andrew E. Caldwell, "Can Recursive Bisection Alone Produce Routable Placements?," dac, pp.477-482, 37th Conference on Design Automation (DAC'00), 2000
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