Quartus® Prime Standard Edition User Guide: Design Compilation

ID 683283
Date 10/22/2021
Document Table of Contents

1.10.2. When Placement and Routing May Not Be Preserved Exactly

The Fitter may have to refit affected nodes if the two nodes are assigned to the same location, due to imported netlists or empty partitions set to re-use a previous post-fit netlist. There are two cases in which routing information cannot be preserved exactly. First, when multiple partitions are imported, there might be routing conflicts because two lower-level blocks could be using the same routing wire, even if the floorplan assignments of the lower-level blocks do not overlap. These routing conflicts are automatically resolved by the Quartus® Prime Fitter re-routing on the affected nets. Second, if an imported LogicLock region is moved in the top-level design, the relative placement of the nodes is preserved but the routing cannot be preserved, because the routing connectivity is not perfectly uniform throughout a device.