Constraint Priority
All constraints are not created equal
- Highest Priority - Timing ignores (TIG)
- FROM:THRU:TO specs / FROM:TO specs
- Lowest Priority - PERIOD specs
“FROM:TO” constraints are further prioritized:
- Highest: FROM PATH-SPECIFIC TO PATH_SPECIFIC
FROM PATH-SPECIFIC TO GLOBAL
- Lowest: FROM GLOBALTO GLOBAL
Over-constraining the design can decrease routability and increase run time
- Use for slower & lower priority global constraints Period constraints
Use faster timespecs for:
- Higher priority path-specific constraints /THRU constraints
Priorities can be explicitly within a constraint CLASS
- Low numbers specify high priority
- TIMESPEC TS01 = FROM A to B 40 PRIORITY 3;