How do you audit wildcard selectors safely?
From PDVerse PnR Interview Handbook · pdVerse Mentor Guide
Short Answer
Measure the collection and inspect representative names before applying a constraint; scope should be explainable and stable.
Technical Explanation
A wildcard is convenient because it can select many objects. That same convenience is dangerous when the pattern grows beyond the interface or hierarchy you intended.
What To Check
• Warning sign: A wildcard catches an entire hierarchy when only one interface was intended. • Inspect: Compare one named object across the related reports; the same object should tell a consistent story. • Correct: Replace broad patterns with robust scoped selectors and re-report affected exceptions or ports.
Command Checks & Actions
• sizeof_collection [get_pins -hierarchical <pattern>]: counts exactly the objects returned by a selector
• get_pins -hierarchical <pattern>: selects instance pins
Run the commands in order. Each line answers a separate part of the check.Healthy, Suspicious & Hard-stop Results
• Expected: Measure the collection and inspect representative names before applying a constraint; scope should be explainable and stable. • Investigate: A wildcard catches an entire hierarchy when only one interface was intended. • Stop before floorplanning when required logic or timing coverage is missing or unexplained. Replace broad patterns with robust scoped selectors and re-report affected exceptions or ports.
Common Mistake
Do not assume the check passed just because ICC2 continued: A wildcard catches an entire hierarchy when only one interface was intended. Fix or narrowly justify the named objects, then rerun the same command.
What The Interviewer Is Testing
Be ready to explain why this matters before floorplanning: A wildcard catches an entire hierarchy when only one interface was intended.
Follow-up Question & Model Response
Model response: “I would save the report, inspect one affected object in the correct block and scenario, and make or request this correction: Replace broad patterns with robust scoped selectors and re-report affected exceptions or ports. Then I would reopen the clean checkpoint and rerun the same evidence.”
Practical Example
Symptom: A wildcard catches an entire hierarchy when only one interface was intended. Corrective path: Replace broad patterns with robust scoped selectors and re-report affected exceptions or ports.
Continue practising