15.7.10 Assigning a Net to a Region
Assigning a net to a region results in assigning all instances connected by the net to the specified region. The assignment of all instances of a net to a region packs logic more closely together, which improves (reduces) net delays.
Assigning nets to regions also enables you to apply floorplanning constraints correctly over design iterations. During design iterations you may change your design, causing a change in the instances connected by a particular net. The assignment of a net to a region assigns all instances connected by that net in the current design iteration, enabling your constraints to be applied correctly.
To assign a net to a region:
- In the Regions tab of the Hierarchy window,
right-click a region and choose Assign/Unassign Net from the
right-click menu.
The Assign Nets to Region dialog box appears with the name of the selected region in the Region name field. The dialog box displays all the nets that you can assign to the selected region (as shown in the figure below).
Figure 15-41. Assign Nets to Region Dialog Box 
To display a subset of the unassigned nets, you can create and apply filters.
- To filter the unassigned nets list by a pattern, enter it in the text box to the left of the Filter button, select Matching pattern, and then click Filter. Only the nets that match the pattern appear in the Assignable nets list. For example, enter *INV* to display only unassigned nets containing the characters INV.
- To assign specific nets, select one or more
nets in the Assignable nets list box, and click
Assign.
To select all nets, click Assign All.
Check the Include Driver checkbox to assign all instances, including the driver connected by the selected net, to the region.
- Click OK to continue.
The total number of nets that you can assign, as well as the number of currently selected unassigned nets, appears in the list box.