Optimal register assignment with minimum-delay compensation for latch-based design

In this paper, we propose a novel hold-time guarantee method in latch-based design, which is based on the register sharing approach. Although the register sharing approach is a simple and promising technique, it increases the required number of registers mainly due to the strict register sharing condition compared with conventional design. Therefore, to accelerate the register sharing, we introduce another method, named minimum-delay compensation (MDC). First of all, we formulate the problem to minimize the cost of MDC (estimated by the number of MDC applied FUs) under the specified number of registers. We propose a polynomial algorithm to solve the problem if the available number of FUs is a fixed constant.