The impact of physical synthesis on design performance is increasing as process technology scales. Current physical synthesis flows generally perform a series of individual net list transformations based on local timing conditions. However, such optimizations lack sufficient perspective or scope to achieve timing closure in many cases. To address these issues, the authors develop an integrated transformation system that performs multiple optimizations simultaneously on larger design partitions than existing approaches. Their system, SPIRE, combines physically-aware register retiming, along with a novel form of cloning and register placement.