ECO Regression Discipline: Inputs & Outputs

Inputs and outputs contract

Inputs & Outputs for ECO Regression Discipline focuses on post-ECO regressions caught, corner coverage, signoff approval latency. The goal is to connect observed QoR movement to mechanism, ownership, and regression risk.

Synthesis closure fails when teams optimize against different assumptions. Treat these artifacts as a signed handoff contract.

INPUTS
  - RTL tag and compile switches
  - SDC / policy constraints
  - Library and operating views
  - Optional physical estimates (topo/congestion)

OUTPUTS
  - QoR timing/area/power reports
  - transform/mapping summaries
  - owner-tagged closure memo
  - regression matrix verdict

Flow sequence

SYNTHESIS FLOW — ECO Regression Discipline

RTL + constraints
      |
      v
elaboration + checks
      |
      v
mapping + optimization
      |
      v
QoR reports (timing/area/power)
      |
      v
incremental ECO + regression

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

Ownership map

OWNERSHIP MAP — ECO Regression Discipline

artifact              owner
----------------      -----------------
compile owner       timing closure lead
timing/power owner  verification owner
cross-team review   program owner

Every QoR movement needs a named owner before ECO.

Synthesis deep dive

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

Concept diagram

INCREMENTAL ECO LOOP

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

Metric graph

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