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Synthesis & Logic Optimization · All levels

Incremental Compile: Step-by-Step Walkthrough

Step-by-Step Walkthrough for Incremental Compile.

Step-by-step analysis walkthrough

Use when you own Incremental Compile 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

  • incremental reuse report, changed-cone map, QoR diff

  • QoR dashboard

  • run manifest

  • constraint diff

  • regression matrix

Decision memo template

diagram
SYNTHESIS DECISION MEMO — Incremental Compile
run context:
observed metric:
hypothesis:
fix:
regression:
owners: synthesis owner, CAD owner

Reference visuals

Incremental compile zones

diagram
stable cones: reuse
changed cones: re-optimize
global checks: timing/power consistency

Synthesis deep dive

Incremental and ECO synthesis protect schedule only with strict regression discipline.

Concept diagram

diagram
INCREMENTAL ECO LOOP

identify delta -> localized compile -> patch -> regression -> release

Metric graph

diagram
ECO CYCLE TIME

full compile      ███████████
incremental       █████

Reports and artifacts

  • incremental reuse

  • ECO patch list

  • LEC status

  • regression matrix

Mini case study

Localized compile cut turnaround 40%, but skipped LEC caused rollback.

Debug branches

  • Reuse ratio is not enough

  • Patch locality check

  • Always include equivalence hooks

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

Incremental compile reuses stable optimization regions while targeting changed cones, reducing churn and iteration cost.

Metric: reuse ratio, localized QoR delta, compile turnaround time

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