ECO fixing order

Steps	Name	commands	Fixing mechanisms	Precendence rules
1	Power recovery	fix_eco_power	Cell sizing buffer removal	Does not introduce new timing or DRV violations
2	Fix DRC and noise violations	fix_eco_drc	Cell sizing buffer insertion	Alters setup and hold slacks as needed
3	Fix timing violations	fix_eco_timing	Cell sizing buffer insertion	Setup fixing honors DRC but alters hold slack if needed; Hold fixing honors setup slack and DRC both.
4	Final leakage recovery	fix_eco_power	vt swap	Does not introduce new timing or DRC violations; doesn't change layout