Use the timing summary report after placement to check the critical paths.
- Paths with very large negative setup time slack may require that you check the constraints for completeness and correctness, or logic restructuring to achieve timing closure.
- Paths with very large negative hold time slack are most likely due to incorrect constraints or bad clocking topologies and should be fixed before moving on to route design.
- Paths with small negative hold time slack are likely to be fixed by the router. You can also run
place_designto view a report that breaks down clock resource and load counts by clock region.