gcov Command in Linux
The gcov command is a powerful tool in Linux that provides code coverage analysis for programs compiled with GCC (GNU Compiler Collection). It generates reports that show which parts of your code were executed during a test run and which parts were not. This information is invaluable for improving code quality and identifying potential bugs.
The gcov command helps you understand which parts of your code are being executed and which are not, providing valuable insights into areas that may need more thorough testing or optimization.
Here's a comprehensive guide to understand the various options available in the gcov command.
Table of Contents
Here is a comprehensive guide to the options available with the gcov command in linux −
- Understanding the Gcov Command
- How to use Gcov Command in Linux?
- gcov Command Options
- Examples of Using gcov Command
Understanding the Gcov Command
The most basic use of gcov is to run it against a source file to generate a coverage report. This report will show you the number of times each line of code has been executed, which can be crucial for understanding the behavior of your code during tests.
Gcov is a powerful tool used in conjunction with GCC to analyze program coverage in Linux environments. It's an essential utility for developers looking to optimize their code, ensure thorough testing, and improve program efficiency. Check its version −
gcov -v
How to use Gcov Command in Linux?
The gcov command offers several options to customize its behavior and generate specific code coverage reports. Here's a breakdown of the most commonly used options −
Basic Usage
The gcov command follows a basic syntax where you can specify various options followed by one or more files. The general form is −
gcov [options] files
gcov Command Options
| Options | Descriptions |
|---|---|
| -a, --all-blocks | This option instructs gcov to output execution counts for every basic block, not just those that are part of the main blocks of a line. |
| -b, --branch-probabilities | With this option, gcov will write branch frequencies to the output file and provide a summary of branch information to the standard output. |
| -c, --branch-counts | This will cause gcov to display branch frequencies as the number of branches taken rather than percentages. |
| -d, --display-progress | Use this option to display the progress of the analysis on the standard output. |
| -f, --function-summaries | This option provides summaries for each function in addition to the overall file summary. |
| -i, --json-format | Outputs the gcov data in a JSON format, which is easier to parse and doesn't require the source code for generation. |
| -j, --human-readable | This option is for generating a more human-readable output format. |
| -c | Creates a .gcda file for each source file that was compiled with -ftest-coverage. |
| -s | Prints the source code along with the coverage data. |
| -t | Prints the total number of executed statements and branches. Prints the total coverage information. |
| -v | Prints the version information. |
| -x, --hash-filenames | Causes gcov to produce hashed filenames for the output to avoid filename conflicts. |
| -u, --unconditional-branches | Includes unconditional branches in the output, which are normally omitted. |
| -t, --stdout | Directs all output to the standard output instead of files. |
| -s, --source-prefix | This option allows you to strip a specified prefix from the file paths in the output. |
| -h | Prints the command-line usage. |
| -r | Removes the .gcda files after generating the report. |
| -i | Ignore functions that have no executable statements. |
| -l | Lists the line numbers of the source file that were executed. |
| -n | Prints the line numbers in decimal format. |
| -o, --object-directory | Specifies the directory or file that contains the object files gcov needs to analyze. |
| -l, --long-file-names | When using this option, gcov will generate longer, more descriptive names for the output files. Prints the line coverage information. |
| -r, --relative-only | Only output information about the relative execution counts, not absolute ones. Prints the range coverage information. |
| -q, --use-hotness-colors | This option will color the output based on the 'hotness' of the code, indicating how frequently each part is executed. |
| -p, --preserve-paths | Preserves the file system path information for the file being analyzed. Prints the program name and coverage information. |
| -b | Prints the branch coverage information. --branch-probabilities adds branch probabilities to the output, which can help you understand the likelihood of each branch being taken. |
| -c or --branch-counts | or shows the number of times each branch is taken, rather than just the probabilities. Prints the function coverage information. |
| --include regex | Include only functions that match the specified extended regular expression. |
| -n or --no-output | It prevents gcov from creating an output file, which can be useful if you only want to print summary information to the standard output. This tells gcov not to create any output files. |
| --exclude regex | Exclude functions that match the specified extended regular expression. |
gcov also provides options for filtering the data based on regular expressions. gcov also offers a variety of options to tailor the coverage analysis to your needs −
Examples of gcov Command in Linux
Here are some practical examples of how gcov can be used −
- Generating a Coverage Report
- Generate a report with source code
- Generate a report with branch coverage
- Generate an HTML report
- Specify the output file
- Analyzing Branch Coverage
- Suppressing Output File Creation
- Profiling and Optimization
Generating a Coverage Report
Compile your code with the -fprofile-arcs and -ftest-coverage flags, then use gcov to generate a coverage report.
gcc -fprofile-arcs -ftest-coverage myprogram.c gcov myprogram.c
This command will produce a report named sourcefile.c.gcov, which contains the execution counts for each line in your source file.
Generate a report with source code
gcov -s myprogram.c
Generate a report with branch coverage
gcov -b myprogram.c
Generate an HTML report
gcov -x html myprogram.c
Specify the output file
gcov -o coverage.txt myprogram.c
Analyzing Branch Coverage
To analyze branch coverage, include the -b option.
gcov -b myprogram.c
Suppressing Output File Creation
If you don't need the .gcov output file, use the -n option.
gcov -n file.c
By using these options, you can tailor the gcov command to your specific needs and generate the most informative code coverage reports for your projects.
Profiling and Optimization
Using gcov, developers can identify the most frequently executed parts of their code, which is invaluable for performance optimization −
gcov -h
Conclusion
Gcov is a versatile tool that offers a wide range of options for developers to fine-tune their code coverage analysis. By understanding and utilizing these options effectively, one can significantly enhance the quality and performance of their software.
The gcov command in Linux is a powerful tool used for analyzing the coverage of your code. It is a part of the GNU Compiler Collection (GCC) and is utilized in conjunction with GCC to test the coverage of your programs.