In some situations, it might be necessary to manually change a place_design clocking floorplan. This article describes how to do this.
The current floorplan for a design that has already been placed can be found by using the report_clock_utilization command.
The "-write_xdc" option will also be needed in order to save the constraints to an XDC file.
report_clock_utilization -write_xdc floorplan.xdc
The floorplan.xdc file can then be edited. A specific example of this would be to add a clock region that the original floorplan did not use, as shown below.
After making the edits to the constraints file, it can be added as a constraints source, and implementation can be rerun.
Note that the pblock will be viewable from an open implemented design, as this pblock is now a user defined pblock, and not a placer generated one.