Macros overlap or extend outside the parent boundary after refinement. What is the correct debug path?
From PDVerse PnR Interview Handbook · pdVerse Mentor Guide
Short Answer
Check stale constraints, fixed status, orientation-dependent dimensions, snap movement, relative-location constraints, voltage areas, and which floorplan version was loaded.
Technical Explanation
The visible overlap is a symptom; the owning constraint or transformation is the cause. Use dp_pre_macro_placement and floorplan rules to identify exact objects, then compare their constraints and coordinates.
Formula Or Decision Rule
Decision rule: no required macro or voltage area overlaps or leaves its legal parent region.
What To Check
• Warning sign: Objects are moved locally while the stale constraint recreates the violation later. • Inspect: choose one affected region, macro, row, pin, path, or net and trace the physical cause. • Correct: Correct the owning constraint or geometry, regenerate placement, and rerun from a clean checkpoint.
Command Checks & Actions
• check_design -checks {dp_pre_macro_placement}: runs named design-planning check groups
• check_floorplan_rules -objects <macro_collection>: reports configured floorplan-rule violations
Run only the commands needed for this question. Save the report with the floorplan version and analysis context.Healthy, Suspicious & Hard-stop Results
• Healthy: Check stale constraints, fixed status, orientation-dependent dimensions, snap movement, relative-location constraints, voltage areas, and which floorplan version was loaded. • Suspicious: Objects are moved locally while the stale constraint recreates the violation later. • Hard stop: required legality or physical feasibility is missing or unexplained. Correct the owning constraint or geometry, regenerate placement, and rerun from a clean checkpoint.
Common Mistake
Do not hide the symptom with an arbitrary utilisation, halo, channel, blockage, pin move, or die-size change. Objects are moved locally while the stale constraint recreates the violation later.
What The Interviewer Is Testing
The interviewer is testing whether you can connect “Macros overlap or extend outside the parent boundary after refinement. What is the correct debug path?” 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 objects are moved locally while the stale constraint recreates the violation later. I would use the named objects and reports to decide whether to iterate, waive, or return the issue.”
Practical Example
Symptom: Objects are moved locally while the stale constraint recreates the violation later. Corrective path: Correct the owning constraint or geometry, regenerate placement, and rerun from a clean checkpoint.
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