afl-cov uses test case files produced by the AFL fuzzer afl-fuzz
to generate gcov code coverage results for a targeted binary. Code
coverage is interpreted from one case to the next by afl-cov in
order to determine which new functions and lines are hit by AFL
with each new test case. Further, afl-cov allows for specific lines
or functions to be searched for within coverage results, and when
a match is found the corresponding test case file is displayed.
This allows the user to discover which AFL test case is the first
to exercise a particular function. In addition, afl-cov produces a
"zero coverage" report of functions and lines that were never
executed during any AFL fuzzing run.

Although of no use to AFL itself, the main application of afl-cov
is to wrap some automation around gcov together with AFL test cases
and thereby provide data on how to maximize code coverage with AFL
fuzzing runs. Manual interpretation of cumulative gcov results from
AFL test cases is usually still required, but the "fiddly" steps
of iterating over all test cases and generating code coverage reports
(along with the "zero coverage" report) is automated by afl-cov.