When using the incremental implementation flow, avoid the following:
- Do not floorplan incremental implementation runs.
Pblock placement is overridden by reference checkpoint placement.
- Do not overconstrain the placer.
Overconstraining the design in the incremental implementation run can severely impact reuse, because the tools try to meet a target WNS that is artificially altered. To avoid overconstraining, do one of the following:
- Remove any overconstraining at the placer by modifying the constraints that are applied.
- Apply the following command to the incremental run. Note: This command does not affect non-incremental runs but ignores all user-applied clock uncertainty constraints.
config_implementation { {incr.ignore_user_clock_uncertainty 1}}