Timed Supersetting and the Synthesis of Telescopic Units

In high-performance systems, variable-latency units are often employed to improve the average throughput when the worst-case delay exceeds the cycle time. Although such units have traditionally been hand-designed, recent results have shown that variable-latency units can be automatically generated. Unfortunately, the existing synthesis procedure has limited applicability due to its computational complexity.In this work, we define and study an optimization problem, timed supersetting, whose solution is at the kernel of the procedure for automatic generation of variable-latency units. We contribute a new algorithm for solving timed supersetting in the most difficult case, that is, when the timing behavior of the circuits is expressed through an accurate delay model. The proposed solution overcomes the complexity limitation of previous approaches, and its robustness is experimentally demonstrated by obtaining high-throughput, variable-latency implementations for all the largest circuits in the {\rm Iscas'85} and Iscas'89 benchmark suites.