1. One or more computer-readable non-transitory storage media embodying software comprising instructions operable when executed to: display, in a graphical user interface (GUI), a layout of an integrated circuit (IC), wherein the layout comprises a hierarchy of modules; receive a selection of a module in the hierarchy of modules; replace, in the displayed layout, the selected module with a plurality of sub-modules comprising, with respect to the hierarchy, children of the selected module; perform a data flow analysis, wherein the data flow analysis is based on a trace of data paths through the sub-modules; and display flylines in the GUI based on results of the data flow analysis.