Automating addition of power supply rails, fences, and level translators to a modular circuit design

A specification for a modular circuit design includes a mapping from global clock domains to global voltage domains. A processor assigns, to a first instance of a clocked primitive component, a global voltage domain based on which global clock domain clocks the first instance, automatically adds, to the modular circuit design, first power supply rails to power the first instance, and connects the first power supply rails from the first instance to a first power supply for a first global voltage domain. The processor assigns, to a second instance of the clocked primitive component, a second global voltage domain based on which global clock domain clocks the second instance, automatically adds second power supply rails to power the second instance, and connects the second power supply rails to a second power supply for a second global voltage domain. The processor may perform further processing on the updated modular circuit design.