A timing-driven soft-macro placement and resynthesis method in interaction with chip floorplanning

In this paper, we present a complete chip design method which incorporates a soft-macro placement and resynthesis method in interaction with chip floorplanning for area and timing improvements. We present a performance-driven soft-macro clustering and placement method which preserves hardware descriptive language (HDL) design hierarchy to guide the soft-macro placement process. We develop a timing-driven design flow to exploit the interaction between HDL synthesis and physical design tasks. During each design iteration, we resynthesize soft macros with either a relaxed or a tightened timing constraint which is guided by the post-layout timing information. The goal is to produce area-efficient designs while satisfying the timing constraints. Experiments on a number of industrial designs ranging from 75-K to 230-K gates demonstrate that the proposed soft-macro clustering and placement method improves critical-path delays on an average of 22%. Furthermore, the results show that by effectively relaxing the timing constraint of noncritical modules and tightening the timing constraint of critical modules, a design can achieve 11% to 30% timing improvements with little to no increase in chip area.

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