Rows remain under macros or blockages. Why is that dangerous?
From PDVerse PnR Interview Handbook · pdVerse Mentor Guide
Short Answer
They inflate nominal placeable area and can mislead early placement, utilisation, or legality. Determine whether the rows should be cut, made transparent by methodology, or associated differently.
Technical Explanation
A painted parking space under a building is not usable capacity. Check macro status, keepouts, blockage purpose, site arrays, voltage areas, and whether the floorplan was updated after macro movement.
Formula Or Decision Rule
Decision rule: reported usable rows match the space where intended cells can actually be placed.
What To Check
• Warning sign: The team counts the hidden row area as whitespace. • Inspect: choose one affected region, macro, row, pin, path, or net and trace the physical cause. • Correct: Regenerate or trim rows and recompute usable capacity before rerunning placement/congestion.
Command Checks & Actions
• report_design -floorplan: reports the floorplan state understood by the tool
• check_design -checks {dp_pre_macro_placement}: runs named design-planning check groups
Run only the commands needed for this question. Save the report with the floorplan version and analysis context.Healthy, Suspicious & Hard-stop Results
• Healthy: They inflate nominal placeable area and can mislead early placement, utilisation, or legality. Determine whether the rows should be cut, made transparent by methodology, or associated differently. • Suspicious: The team counts the hidden row area as whitespace. • Hard stop: required legality or physical feasibility is missing or unexplained. Regenerate or trim rows and recompute usable capacity before rerunning placement/congestion.
Common Mistake
Do not hide the symptom with an arbitrary utilisation, halo, channel, blockage, pin move, or die-size change. The team counts the hidden row area as whitespace.
What The Interviewer Is Testing
The interviewer is testing whether you can connect “Rows remain under macros or blockages. Why is that dangerous?” to measurable physical evidence and an owned correction.
Follow-up Question & Model Response
Follow-up probe: What would make you change your decision? Model response: “I would change it if the same controlled rerun shows that the team counts the hidden row area as whitespace. I would use the named objects and reports to decide whether to iterate, waive, or return the issue.”
Practical Example
Symptom: The team counts the hidden row area as whitespace. Corrective path: Regenerate or trim rows and recompute usable capacity before rerunning placement/congestion.
Continue practising