Method and apparatus for generating an area constraint for a module in a programmable logic device (PLD) is described. In an example, first logic resources are selected in a floorplan of the PLD for implementing a first module of a circuit design. A routing resource area constraint is defined that reserves first routing resources associated with the first logic resources and second routing resources associated with second logic resources. The second routing resources are required for use of the first logic resources. A logic resource area constraint is defined that reserves the first logic resources and excludes the second logic resources. The logic resource constraint area for the module may be non-rectangular or include multiple disjoint regions.