Synthesis & Logic Optimization · All levels

ECO Regression Discipline: Step-by-Step Walkthrough

Step-by-Step Walkthrough for ECO Regression Discipline.

Step-by-step analysis walkthrough

Use when you own ECO Regression Discipline in a synthesis closure review.

Confirm exact run context (RTL/SDC/lib/switch set).
Open section QoR dashboard and identify first drift.
Inspect topic-level report for mechanism evidence.
Determine owner and candidate reversible action.
Apply one change only; avoid bundled fixes.
Run full timing/area/power checks.
Validate side effects on neighboring path groups.
Publish memo with outcome and residual risk.

Artifacts to collect

regression matrix, signoff checklist, release memo
QoR dashboard
run manifest
constraint diff
regression matrix

Decision memo template

diagram

SYNTHESIS DECISION MEMO — ECO Regression Discipline
run context:
observed metric:
hypothesis:
fix:
regression:
owners: timing closure lead, verification owner, program owner

Reference visuals

Regression matrix

diagram

[ ] setup corners
[ ] hold corners
[ ] power checks
[ ] equivalence
[ ] handoff report update

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

Regression discipline prevents late-stage surprises by enforcing setup/hold, power, and equivalence checks after every ECO wave.

Metric: post-ECO regressions caught, corner coverage, signoff approval latency

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