Summary
Add standard timing signoff metrics to simulation output: Worst Negative Slack (WNS), Total Negative Slack (TNS), Worst Hold Slack (WHS), Total Hold Slack (THS).
Current State
GEM reports individual setup/hold violations via event buffer but doesn't aggregate them into the standard metrics that timing engineers look at first.
Proposed Approach
- Accumulate per-DFF worst slack across all simulation cycles
- At end of simulation, report:
- WNS: Worst (most negative) setup slack across all DFFs
- TNS: Sum of all negative setup slacks
- WHS: Worst hold slack
- THS: Sum of all negative hold slacks
- Number of violating endpoints (setup and hold separately)
- Support JSON output format for CI integration
- Optional: histogram of slack distribution
Impact
Medium — these are the first numbers any timing signoff engineer checks. Essential for usability.
Effort
Low — aggregate existing violation data that's already collected.
Summary
Add standard timing signoff metrics to simulation output: Worst Negative Slack (WNS), Total Negative Slack (TNS), Worst Hold Slack (WHS), Total Hold Slack (THS).
Current State
GEM reports individual setup/hold violations via event buffer but doesn't aggregate them into the standard metrics that timing engineers look at first.
Proposed Approach
Impact
Medium — these are the first numbers any timing signoff engineer checks. Essential for usability.
Effort
Low — aggregate existing violation data that's already collected.