  While it is easy to automate coverage data collection, it is a time
consuming/difficult/expensive manual process to analyze the data so that it can
be acted upon. Complexity arises from numerous sources, of which untested or
poorly tested legacy code and third-party libraries are two of the most common.
  Differential coverage and date binning are methods of combining coverage data
and project/file history to determine if goals have been met and to identify
areas of code which should be prioritized. These methods can be applied to any
coverage metric which can be associated with a location -- statement, function,
expression, toggle, etc. -- and to any language, including both software (C++,
Python, etc.) and hardware description languages (SystemVerilog, VHDL). The
goal of these approaches is to reduce the cost and the barrier to entry of
using coverage data analysis in large-scale projects.
  The approach is realized in gendiffcov, a recently released open-source tool.
