"gcov" Recipe Command for C/C++ Coverage Metrics Gathering

[Chandler Carruth <chandlerc@…>]

Provide a RecipeCommand for C/C++ coverage measuring. The "gcov" command, part of the GCC project, provides the following coverage metrics:

• Line coverage.
• Branch coverage.
• Call coverage.

At least the line coverage should be provided using the existing framework in Bitten. Other metrics would also be useful.

[Chandler Carruth <chandlerc@…>]

Output from a run of "gcov" looks something like the below:

chandlerc@vulcan ~/code/string $ gcov -b -c -n -o src/test_stringUnitTests-rangeBase.o src/rangeBase.cpp
File `/usr/lib/gcc/i686-pc-linux-gnu/3.4.4/include/g++-v3/bits/locale_facets.tcc'
Lines executed:0.00% of 11
Branches executed:0.00% of 10
Taken at least once:0.00% of 10
Calls executed:0.00% of 5

File `src/rangeBase.cpp'
Lines executed:45.81% of 884
Branches executed:54.27% of 398
Taken at least once:36.68% of 398
Calls executed:48.19% of 249

File `./include/strand.hpp'
Lines executed:50.00% of 4
No branches
Calls executed:100.00% of 1

File `./include/srange.hpp'
Lines executed:100.00% of 3
No branches
Calls executed:100.00% of 1

File `./include/sdata.hpp'
Lines executed:100.00% of 2
No branches
No calls

File `/usr/lib/gcc/i686-pc-linux-gnu/3.4.4/include/g++-v3/bits/stl_algobase.h'
Lines executed:0.00% of 4
Branches executed:0.00% of 2
Taken at least once:0.00% of 2
No calls

File `/usr/lib/gcc/i686-pc-linux-gnu/3.4.4/include/g++-v3/iostream'
Lines executed:100.00% of 1
Branches executed:100.00% of 4
Taken at least once:50.00% of 4
Calls executed:100.00% of 3

I would recommend counting all blocks not belonging to a system file. The pattern of simply looking for absolute paths should work to eliminate these.

[Chandler Carruth <chandlerc@…>]

Initial patch to add a gcov command.

[Chandler Carruth <chandlerc@…>]

New patch w/ tabs replaced...

[Chandler Carruth <chandlerc@…>]

New patch... bugs fixed... one still left...

[Chandler Carruth <chandlerc@…>]

Working version of patch. Tested it on my system, got correct statistics back.

[cmlenz]

That last patch looks pretty nice. Thanks!

[cmlenz]

So gcov doesn't provide information about exactly which lines were executed, or does it?

Also, I think I'm going to remove the branch parsing from the patch before applying it. Currently it's just unused code.

[Chandler Carruth <chandlerc@…>]

It can. you can have it generate a file describing the execution of each line, as well as the branches and calls for each line. =] I am not currently generating these files, but it would not be terribly difficult to restructure the calls to gcov in order to generate the files.

My question is: what does it gain you? and at what cost? I'm not sure i want to parse the 10s of 1000s of lines of code in my fairly small projects... Let me know however if this is a priority. I'll whip something together to generate and parse the files.

[cmlenz]

Cleaned up patch with unit tests

[cmlenz]

I've just attached a cleaned up version of your patch (it removes the branch coverage stuff, which isn't being reported yet anyway). This also has a few unit tests. Can you please test the patch and let me know if it works for you?

On the topic of recording the exact lines covered in each file… the idea is that in the future, Bitten would provide an annotator for the Trac browser that would display the coverage in the file view. Obviously that feature isn't there yet, so the question was more out of curiosity, rather than implying that it would be needed for the <c:gcov> command now.

[cmlenz]

Patch applied in [314].