Timing-driven Steiner trees are (practically) free

摘要: Traditionally, rectilinear Steiner minimum trees (RSMT) are widely used for routing estimation in design optimizations like floorplanning and physical synthesis. Since it optimizes wirelength, an RSMT may take a "non-direct" route to sink, which give the designer unnecessarily pessimistic view of delay sink. Previous works have addressed this issue through performance-driven constructions, arborescence, critical sink based constructions. Physical synthesis flows been reticent adapt universal timing-driven constructions out fear that they too expensive (in terms resource capacitance). This paper studies several different tree order show ones superior performance. A key result is add at most 2%-4% extra capacitance, thus promising avenue today's increasingly aggressive P&R flows. We demonstrate using production flow topologies can be easily embedded into incremental subflow obtain significantly improved timing (3.6% 5.1% improvements cycle time two industry testcases) practically no cost wirelength or routability.