Why separate sequential, combinational, memory, and macro inventories?
From PDVerse PnR Interview Handbook · pdVerse Mentor Guide
Short Answer
Class totals reveal missing domains or views that a single overall cell count can hide.
Technical Explanation
Treat this as a readiness check. It should produce named objects and a result that another engineer can repeat from the same handoff.
What To Check
• Warning sign: The total count matches while a memory hierarchy is black-boxed or a register bank disappeared. • Inspect: Compare one named object across the related reports; the same object should tell a consistent story. • Correct: Query and compare each class using supported attributes for the loaded libraries, then reconcile with synthesis evidence.
Command Checks & Actions
• get_cells -hierarchical *: selects design cells
• report_unbound: lists objects that did not resolve
Run the commands in order. Each line answers a separate part of the check.Healthy, Suspicious & Hard-stop Results
• Expected: Class totals reveal missing domains or views that a single overall cell count can hide. • Investigate: The total count matches while a memory hierarchy is black-boxed or a register bank disappeared. • Stop before floorplanning when required logic or timing coverage is missing or unexplained. Query and compare each class using supported attributes for the loaded libraries, then reconcile with synthesis evidence.
Common Mistake
Do not assume the check passed just because ICC2 continued: The total count matches while a memory hierarchy is black-boxed or a register bank disappeared. 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: The total count matches while a memory hierarchy is black-boxed or a register bank disappeared.
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: Query and compare each class using supported attributes for the loaded libraries, then reconcile with synthesis evidence. Then I would reopen the clean checkpoint and rerun the same evidence.”
Practical Example
Symptom: The total count matches while a memory hierarchy is black-boxed or a register bank disappeared. Corrective path: Query and compare each class using supported attributes for the loaded libraries, then reconcile with synthesis evidence.
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