Computer-Aided Design, International Conference on (2003)
San Jose, CA
Nov. 9, 2003 to Nov. 13, 2003
Paul G. Villarrubia , IBM, Corporation, Austin, TX
Saurabh N. Adya , University of Michigan, Ann Arbor
Igor L. Markov , University of Michigan, Ann Arbor
In the context of physical synthesis, large-scale standard-cell placement algorithms must facilitate incremental changes to layout, both local and global. In particular, flexible gate sizing, net buffering and detail placement require a certain amount of unused space in every region of the die. The need for "local" whitespace is further emphasized by temperature and power-density limits. Another requirement, the stability of placement results from run to run, is important to the convergence of physical synthesis loops. Indeed, logic resynthesis targetting local congestion in a given placement or particular critical paths may be irrelevant for another placement produced by the same or a different layout tool.<div></div> In this work we offer solutions to the above problems. We show how to tie the results of a placer to a previously existing placement, and yet leave room for optimization. In our experiments this technique produces placements with similar congestion maps. We also show how to trade-off wirelength for routability by manipulating whitespace. Empirically, our techniques improve circuit delay of sparse layouts in conjunction with physical synthesis.<div></div> In the context of earlier proposed techniques for mixed-size placement, we tune a state-of-the-art recursive bisection placer to better handle regular netlists that offer a convenient way to represent memories, datapaths and random-logic IP blocks. These modifications and better whitespace distribution improve results on recent mixed-size placement benchmarks.
Paul G. Villarrubia, Saurabh N. Adya, Igor L. Markov, "On Whitespace and Stability in Mixed-Size Placement and Physical Synthesis", Computer-Aided Design, International Conference on, vol. 00, no. , pp. 311, 2003, doi:10.1109/ICCAD.2003.1257687