GCOV MANUAL PDF

A utility to run gcov and summarize the coverage in simple reports. Defaults to --root and --object-directory. Config key: search-path. Please include this output in bug reports. File names are reported relative to this root.

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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 profiling 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. Software developers also use coverage testing in concert with testsuites, to make sure software is actually good enough for a release.

Testsuites can verify that a program works as expected; a coverage program tests to see how much of the program is exercised by the testsuite. 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. 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 helpfulthey 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. You can use these logfiles along with gprof to aid in fine-tuning the performance of your programs.

It is not compatible with any other profiling or test coverage mechanism. Normally gcov outputs execution counts only for the main blocks of a line. With this option you can determine if blocks within a single line are not being executed. This option allows you to see how often each branch in your program was taken. Unconditional branches will not be shown, unless the -u option is given.

The JSON file is compressed with gzip compression algorithm and the files have. We use red color for non-exceptional lines and cyan for exceptional. Same colors are used for basic blocks with -a option.

For example, if the header file x. This can be useful if x. If you use the -p option, both the including and included file names will be complete path names. The default is to show mangled function names. If a directory is specified, the data files are in that directory and named after the input file name, without its extension.

If a file is specified here, the data files are named after that file, without its extension. Without this option, just the filename component is used. This is useful if sourcefiles are in several different directories. Legend of the color scale is printed at the very beginning of the output file.

Absolute paths are usually system header files and coverage of any inline functions therein is normally uninteresting.

This option is useful when building in a separate directory, and the pathname to the source directory is not wanted when determining the output file names.

Note that this prefix detection is applied before determining whether the source file is absolute. Unconditional branches are normally not interesting.

This can lead to long filenames that can overflow filesystem limits. This option creates names of the form source-file md5. The option is an alternative to the --preserve-paths on systems which have a filesystem limit. Otherwise it will not be able to locate the source files. These contain the coverage information of the source file they correspond to. The mangledname part of the output file name is usually simply the source file name, but can be something more complicated if the -l or -p options are given.

Refer to those options for details. If you invoke gcov with multiple input files, the contributions from each input file are summed.

Typically you would invoke it with the same list of files as the final link of your executable. This functionality is not supported in Ada. Note that GCC can completely remove the bodies of functions that are not needed -- for instance if they are inlined everywhere. Such functions are marked with -, which can be confusing. Use tag to locate a particular preamble line. When using gcov, you must first compile your program with a special GCC option --coverage.

This tells the compiler to generate additional information needed by gcov basically a flow graph of the program and also includes additional code in the object files for generating the extra profiling information needed by gcov. These additional files are placed in the directory where the object file is located. Running the program will cause profile output to be generated. For each source file compiled with -fprofile-arcs, an accompanying.

For example, if your program is called tmp. Here is a sample: -: 0:Source:tmp. First occurrence presents total number of execution of the line and the next two belong to instances of class Foo constructors. As you can also see, line 30 contains some unexecuted basic blocks and thus execution count has asterisk symbol.

When you use the -a option, you will get individual block counts, and the output looks like this: -: 0:Source:tmp. A multi-line block will only contribute to the execution count of that last line, and other lines will not be shown to contain code, unless previous blocks end on those lines.

The total execution count of a line is shown and subsequent lines show the execution counts for individual blocks that end on that line. After each block, the branch and call counts of the block will be shown, if the -b option is given. Because of the way GCC instruments calls, a call count can be shown after a line with no individual blocks.

As you can see, line 33 contains a basic block that was not executed. When you use the -b option, your output looks like this: -: 0:Source:tmp. For each basic block, a line is printed after the last line of the basic block describing the branch or call that ends the basic block. There can be multiple branches and calls listed for a single source line if there are multiple basic blocks that end on that line.

In this case, the branches and calls are each given a number. There is no simple way to map these branches and calls back to source constructs. In general, though, the lowest numbered branch or call will correspond to the leftmost construct on the source line. For a branch, if it was executed at least once, then a percentage indicating the number of times the branch was taken divided by the number of times the branch was executed will be printed.

Otherwise, the message "never executed" is printed. For a call, if it was executed at least once, then a percentage indicating the number of times the call returned divided by the number of times the call was executed will be printed. The execution counts are cumulative. If the example program were executed again without removing the. This is potentially useful in several ways. For example, it could be used to accumulate data over a number of program runs as part of a test verification suite, or to provide more accurate long-term information over a large number of program runs.

The data in the. For each source file compiled with -fprofile-arcs, the profiling code first attempts to read in an existing.

It then adds in the new execution counts and finally writes the data to the file. Using gcov with GCC Optimization If you plan to use gcov to help optimize your code, you must first compile your program with a special GCC option --coverage. Aside from that, you can use any other GCC options; but if you want to prove that every single line in your program was executed, you should not compile with optimization at the same time.

On some machines the optimizer can eliminate some simple code lines by combining them with other lines. For example, code like this: if a! Hence the gcov output looks like this if you compiled the program with optimization: if a!

In one sense this result is correct, because there was only one instruction representing all four of these lines. However, the output does not indicate how many times the result was 0 and how many times the result was 1. Inlineable functions can create unexpected line counts. Line counts are shown for the source code of the inlineable function, but what is shown depends on where the function is inlined, or if it is not inlined at all. If the function is not inlined, the compiler must emit an out of line copy of the function, in any object file that needs it.

If fileA. When fileA. Unfortunately, it will not remove the coverage counters for the unused function body. Hence when instrumented, all but one use of that function will show zero counts. If the function is inlined in several places, the block structure in each location might not be the same. For instance, a condition might now be calculable at compile time in some instances.

Because the coverage of all the uses of the inline function will be shown for the same source lines, the line counts themselves might seem inconsistent. If an executable loads a dynamic shared object via dlopen functionality, -Wl,--dynamic-list-data is needed to dump all profile data.

Profiling run-time library reports various errors related to profile manipulation and profile saving. That can help users to find profile clashing which leads to a misleading profile.

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GCOV MANUAL PDF

Aram Dynamic code coverage analysis is much more elaborate and requires the test code to be executed on the target. It also adds overview pages for easy navigation within the file structure. Archived from the original on The line counts can be seen in the first column of the output. It generates html files and integrates well with web based CI systems.

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Shagis This creates an instrumented executable which contains additional instructions that record the number of times each line of the program is executed. This command is inspired by the Python coverage. There is a unix stackexchange entry for a similar problem. By using this site, you agree to manuaal Terms of Use and Privacy Policy. When using gcov, you mxnual first compile your program with —coverage GCC option. When the code base grows, manual testing fails to meet the requirements and we have to move into automated systems for testing. The article mankal solely from the viewpoint of a C programmer working on a Linux PC or similar systems What is coverage?

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Description[ edit ] gcov produces a test coverage analysis of a specially instrumented program. The options -fprofile-arcs -ftest-coverage should be used to compile the program for coverage analysis first option to record branch statistics and second to save line execution count ; -fprofile-arcs should also be used to link the program. It takes source files as command-line arguments and produces an annotated source listing. Each line of source code is prefixed with the number of times it has been executed; lines that have not been executed are prefixed with " ". This annotated source file can be used with gprof , another profiling tool, to extract timing information about the program. This creates an instrumented executable which contains additional instructions that record the number of times each line of the program is executed.

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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 profiling 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. Software developers also use coverage testing in concert with testsuites, to make sure software is actually good enough for a release. Testsuites can verify that a program works as expected; a coverage program tests to see how much of the program is exercised by the testsuite. 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.

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