gf12/ibex: tighten clock period so setup WS < 0

[eder-matheus]

• Remove SETUP_SLACK_MARGIN (180) and HOLD_SLACK_MARGIN (50). The flow
  only times the BC corner, so the margins over-repaired at BC without
  closing WC. Removing them cut area 18%, power 32% and flow runtime
  from 966 s to 307 s.
• Clock period 1020 -> 840 ps.
  Finish: setup WS -34 ps, TNS -9.4 ns (493 endpoints), hold clean, 0 DRC.

[gemini-code-assist]

Code Review

This pull request removes the setup and hold slack margins from the configuration file and decreases the clock period constraint from 1020 to 840. However, decreasing the clock period to 840 results in negative setup slack and timing violations. It is recommended to increase the clock period to at least 880 to ensure a timing-closed design.

[openroad-ci]

🔍 QoR check

Metrics reflect the PR merge build — i.e. what will land on the target branch.

Commit fc1342a · Jenkins build #1 · Baseline: build · View build on dashboard

62 design(s) checked — 0 with regression(s), 0 without a comparable baseline.