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gcov

test coverage analysis program

TLDR

Generate a coverage report named file.cpp.gcov
$ gcov [path/to/file.cpp]
Write individual execution counts for every basic block
$ gcov -a [path/to/file.cpp]
Write branch frequencies to output and print summary as percentage
$ gcov -b [path/to/file.cpp]
Write branch frequencies as number of branches taken
$ gcov -c [path/to/file.cpp]
Do not create a gcov output file
$ gcov -n [path/to/file.cpp]
Write file level and function level summaries
$ gcov -f [path/to/file.cpp]

SYNOPSIS

gcov [options] source-files

DESCRIPTION

gcov is a test coverage program used with GCC to analyze which parts of a program have been executed during testing. It helps identify untested code paths, improving test suite completeness.To use gcov, compile your program with -fprofile-arcs -ftest-coverage (or --coverage). After running the program, gcov reads the generated .gcno and .gcda files to produce annotated source listings showing execution counts for each line.Output files (*.gcov) contain the original source code annotated with execution counts. Lines marked ##### were never executed. Branch information helps identify untested conditional paths.

PARAMETERS

-a, --all-blocks

Write individual execution counts for every basic block
-b, --branch-probabilities
Write branch frequencies to output file as percentages
-c, --branch-counts
Write branch frequencies as counts rather than percentages
-f, --function-summaries
Output summaries for each function in addition to file summary
-n, --no-output
Do not create gcov output file
-l, --long-file-names
Use long file names for output files
-p, --preserve-paths
Preserve complete path information in output file names
-o, --object-directory DIR
Search for object files in DIR
-s, --source-prefix PREFIX
Remove source path prefix for shorter output names

INSTALL

sudo apt install gcc
sudo dnf install gcc
sudo pacman -S gcc
sudo apk add gcc
sudo zypper install gcc
brew install gcc
nix profile install nixpkgs#gcc

CAVEATS

Requires programs to be compiled with special GCC flags. Only works with GCC-compiled code. Running the program multiple times accumulates coverage data unless .gcda files are deleted between runs. Inline functions may show misleading counts.

HISTORY

gcov has been part of the GNU Compiler Collection (GCC) since the early 1990s. It evolved alongside GCC's profiling capabilities and remains a fundamental tool for C/C++ code coverage analysis in the open-source ecosystem.

SEE ALSO

gcc(1), lcov(1), gprof(1)

RESOURCES

Documentation