Synthesis & Logic Optimization · All levels
Scenario: QoR Storm: Comparison Matrix
Comparison Matrix for Scenario: QoR Storm.
Comparison matrix
Strong answers compare options by risk, evidence, and regression burden.
+------------------+----------------+----------------+----------------+
| Approach | Strength | Weakness | Best when |
+------------------+----------------+----------------+----------------+
| Conservative | stable | slower | new design spin |
| Balanced | practical | needs monitoring | normal closure |
| Aggressive | fast | higher risk | schedule crunch |
| Structural | durable | long loop | repeat offender |
+------------------+----------------+----------------+----------------+When to choose each approach
Select strategy by risk budget, not convenience.
Interview traps
Skipping manifest diff
No side-effect regression
Evidence comparison
SYNTHESIS EVIDENCE MATRIX — Scenario: QoR Storm
+--------------------+------------------------+--------------------------+-------------------------+
| Evidence | Tells you | Does not prove | Next action |
+--------------------+------------------------+--------------------------+-------------------------+
| compile QoR report | metric movement | root-cause class | inspect transform logs |
| SDC diff | constraint drift | library quality | rerun with baseline SDC |
| library map diff | cell view changes | RTL intent quality | lock/validate lib set |
| topo vs logical QoR | physical correlation | final route signoff | PD trial correlation |
| regression matrix | closure stability | architecture optimality | decide merge/rollback |
+--------------------+------------------------+--------------------------+-------------------------+Synthesis deep dive
Interview readiness comes from repeatable QoR reasoning under pressure.
Concept diagram
INTERVIEW ANSWER SHAPE
context -> metric -> mechanism -> fix -> regression -> ownershipMetric graph
PANEL SCORING
clarity ███████
mechanism ██████
regression █████Reports and artifacts
mock scorecard
scenario debrief
Q&A coverage
framework adherence
Mini case study
Candidate improved by replacing tool-command answers with evidence-driven closure narratives.
Debug branches
State assumptions first
Defend option tradeoffs
Close with rollback/regression
Senior review question
Ask: what evidence proves this QoR move is real and stable?
Key takeaways
State exact run context (RTL, SDC, libs, switches) with every QoR claim.
Re-run timing, area, and power regressions after each synthesis ECO.
Common pitfalls
Comparing runs with mismatched constraints or library views.
Timing-only fixes that violate power or area budgets.
Skipping equivalence checks after structural changes.
Principal synthesis review addendum
QoR storms test run-hygiene fundamentals: constraint diffs, library updates, and compile switches before speculative ECO.
Metric: overnight WNS/TNS regression with no RTL intent change