Placing and routing an interface portion and a main portion of a circuit design

A system, comprising:

• a computer system including:
• a processor;
• and
• a memory configured with instructions that when executed by the processor cause the processor to perform operations including:
• decomposing an interface portion of a circuit design into multiple levels, wherein:
• each level specifies connections between a respective first set of circuit elements and a respective second set of circuit elements,
• the respective second set of circuit elements in each level, except a last level, includes the respective first set of circuit elements in a next level, and
• the respective first set of circuit elements identified in a first level of the multiple levels have fixed locations;
• placing-and-routing the respective second set of circuit elements in the multiple levels by the computer, including completing the placing-and-routing of the respective second set of circuit elements in one level before commencing placing-and-routing of the respective second set of circuit elements in the next level;
• and
• placing-and-routing a main portion of the circuit design by the computer after placing-and-routing the respective second set of circuit elements in the multiple levels.