Synthesis & Logic Optimization · All levels

ECO Netlist Patches: Step-by-Step Walkthrough

Step-by-Step Walkthrough for ECO Netlist Patches.

Step-by-step analysis walkthrough

Use when you own ECO Netlist Patches 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

netlist diff, ECO patch log, post-patch timing report
QoR dashboard
run manifest
constraint diff
regression matrix

Decision memo template

diagram

SYNTHESIS DECISION MEMO — ECO Netlist Patches
run context:
observed metric:
hypothesis:
fix:
regression:
owners: synthesis owner, STA owner, formal owner

Reference visuals

Netlist patch loop

diagram

failing path -> patch cell/net
          -> re-run timing
          -> run equivalence
          -> merge or rollback

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

ECO patching edits gate-level logic for urgent fixes; patch quality depends on locality, observability, and verification closure.

Metric: patch count, setup/hold recovery, patch-induced side effects

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