"penatly_cost" in symbiflow-arch-defs is used to demote certain "unwanted" routes from being explored by the VPR routed until later in the flow. The runtime cost of implementing the "penatly_cost" was found to be unacceptable to the VPR devs, and so another path is required that limits the cost to only paths where penalty costs are being used.

This work is required to enable symbiflow-arch-defs to run on the VPR code base directly, rather than the symbiflow fork of VPR.