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Synthesis & Logic Optimization · All levels

Mapping Debug: Step-by-Step Walkthrough

Step-by-Step Walkthrough for Mapping Debug.

Step-by-step analysis walkthrough

Use when you own Mapping Debug in a synthesis closure review.

  1. Confirm exact run context (RTL/SDC/lib/switch set).

  2. Open section QoR dashboard and identify first drift.

  3. Inspect topic-level report for mechanism evidence.

  4. Determine owner and candidate reversible action.

  5. Apply one change only; avoid bundled fixes.

  6. Run full timing/area/power checks.

  7. Validate side effects on neighboring path groups.

  8. Publish memo with outcome and residual risk.

Artifacts to collect

  • run manifest diff, mapping override list, before/after QoR report

  • QoR dashboard

  • run manifest

  • constraint diff

  • regression matrix

Decision memo template

diagram
SYNTHESIS DECISION MEMO — Mapping Debug
run context:
observed metric:
hypothesis:
fix:
regression:
owners: synthesis owner, CAD owner, library owner

Reference visuals

Mapping debug checklist

diagram
same RTL?
same SDC?
same libs?
same switches?
if yes -> inspect transform choice

Synthesis deep dive

Mapping converts logic intent into real PPA outcomes.

Concept diagram

diagram
MAPPING LOOP

boolean net -> library mapping -> optimization -> report and iterate

Metric graph

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MAPPING IMPACT

depth reduction   ███████
fanout cleanup    █████
runtime overhead  ███

Reports and artifacts

  • mapping summary

  • critical path cell list

  • fanout/slew report

  • library coverage

Mini case study

Cell-heavy critical path improved after restructuring, while blanket buffering had worsened power.

Debug branches

  • Depth issue -> structure

  • Fanout issue -> buffers

  • Library mismatch -> view audit

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

Mapping debug isolates whether QoR regressions come from library views, constraints, or synthesis transforms, then applies minimal reversible fixes.

Metric: failed mapping cases, rule override count, QoR regression root-cause time

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