A small Description of GCOV

Gcov is a test coverage program. Use it in concert with GCC to analyze
your programs to help create more efficient, faster running code and to
discover untested parts of your program. You can use gcov as a profil-
ing tool to help discover where your optimization efforts will best
affect your code. You can also use gcov along with the other profiling
tool, gprof, to assess which parts of your code use the greatest amount
of computing time.

Profiling tools help you analyze your code’s performance. Using a pro-
filer such as gcov or gprof, you can find out some basic performance
statistics, such as:

· how often each line of code executes

· what lines of code are actually executed

· how much computing time each section of code uses

Once you know these things about how your code works when compiled, you
can look at each module to see which modules should be optimized. gcov
helps you determine where to work on optimization.

Software developers also use coverage testing in concert with test-
suites, to make sure software is actually good enough for a release.
Testsuites can verify that a program works as expected; a coverage pro-
gram tests to see how much of the program is exercised by the test-
suite. Developers can then determine what kinds of test cases need to
be added to the testsuites to create both better testing and a better
final product.

You should compile your code without optimization if you plan to use
gcov because the optimization, by combining some lines of code into one
function, may not give you as much information as you need to look for
‘hot spots’ where the code is using a great deal of computer time.
Likewise, because gcov accumulates statistics by line (at the lowest
resolution), it works best with a programming style that places only
one statement on each line. If you use complicated macros that expand
to loops or to other control structures, the statistics are less help-
ful---they only report on the line where the macro call appears. If
your complex macros behave like functions, you can replace them with
inline functions to solve this problem.

gcov creates a logfile called sourcefile.gcov which indicates how many
times each line of a source file sourcefile.c has executed. You can
use these logfiles along with gprof to aid in fine-tuning the perfor-
mance of your programs. gprof gives timing information you can use
along with the information you get from gcov.

gcov works only on code compiled with GCC. It is not compatible with
any other profiling or test coverage mechanism.