Gcov is a source code coverage analysis and statement-by-statement profiling tool. Gcov generates exact counts of the number of times each statement in a program is executed and annotates source code to add instrumentation. Gcov comes as a standard utility with the GNU Compiler Collection (GCC) suite. Using $ gcov -version Apple LLVM version 9.0.0 (clang-900.0.38) Optimized build. Default target: x8664-apple-darwin16.7.0 Host CPU: sandybridge geninfo seems to parse this output in a way that causes lcov to think this the equivalent o. I don't think the test has ever passed on Darwin. FAIL: g.dg/gcov/pr16855.C -std=gnu14 line 21: is #####:should be 1 FAIL: g.dg/gcov/pr16855.C -std=gnu14 line 45: is #####:should be 1 (and corresponding fails on other std versions) The analysis is this: Darwin.does. run the DTORs, but they run before the profile DTORs, and therefore are not recorded in the output.
This article has been migrated from my original post at embeddedinn.wordpress.com.
Any large code base needs to be incrementally tested for each release for regressions and bugs. When the code base grows, manual testing fails to meet the requirements and we have to move into automated systems for testing. Once a test is written, we have excellent continuous integration systems like Jenkins or Cruise Control to validate the tests against any changes made on the code. However, the CI system is only as effective as the test. If the test does not cover all use cases, then there is no point in running the tests in CI.
This article intends to illustrate the use of ‘gcov’ to estimate the dynamic coverage of a test. The article speaks solely from the viewpoint of a C programmer working on a Linux PC (or similar systems)
What is coverage?
All large scale, usable C code is written in the form of blocks of code enclosed in functions. A block can be a set of simple execution statements or a logical branch.
The ideal test code should logically call all the functions and execute all statements in the blocks. The percentage of lines of actual code that gets executed when a test code runs is called the coverage of the test code. More the number of lines of code that is tested, less is the probability to get a last minute surprise bug.
![C++ C++](/uploads/1/1/9/8/119846030/643751120.jpg)
There are two types of coverage analysis that is possible.
Static code coverage analysis is done by analyzing the test code and the actual code to primarily estimate the function call coverage. Static code coverage analysis is much faster and simpler since the generated object file need not be executed. This is particularly handy in the case of small scale embedded systems.
Dynamic code coverage analysis is much more elaborate and requires the test code to be executed on the target. It also requires the object file to be generated with special compilation options. However, it gives much more detailed analysis of how effective the test is.
For obvious reasons, it is not practical to manually compute the coverage of a test code. Thus we have some tools that can compute the coverage of our test code for us. We will now look into the details of how ‘gcov’ can be used for dynamic code coverage analysis.
Gcov Macros
GCOV
As per Wikipedia, Gcov is a source code coverage analysis and statement-by-statement profiling tool. Gcov generates exact counts of the number of times each statement in a program is executed and annotates source code to add instrumentation. Gcov comes as a standard utility with GNU CC Suite (GCC)
Gcov provides the following details:
- How often each line of code executes
- What lines of code are actually executed
- How much computing time each section of code uses
Getting Started With GCOV
When using gcov, you must first compile your program with
–coverage
GCC option.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 (.gcno) are placed in the directory where the object file is located.
Once the object file is generated, execute it once to get the profile file (.gcda)
Once we have the
gcna
and gcda
files , we can now run gcov.To illustrate the usage of gcov, we will consider a very minimal library (
lib.c
) and it test suite (test.c
) .lib.c
test.c
Compilation command for the test code :
gcc --coverage lib.c test.c –o test
This will generate the following files:
lib.gcno
– library flow graphtest.gcno
– test code flow graphtest
– test code executable
Now, execute the test code object file. This will generate the following files
lib.gcda
– library profile outputtest.gcda
– test code profile output
Now we have all the inputs required for gcov to generate the coverage report. To generate the coverage report, run the following command
gcov -abcfu lib.c
Coverage summary will be displayed as below when gcov finishes execution:
Detailed coverage report will be available in the lib.c.gcov file generated by gcov
Each block is marked by a line with the same line number as the last line of the block and the number of branch and calls in the block.
Each function is preceded with a line showing the number of times the function is called, number of times it returns and the percentage of function blocks that were executed.
Each line of executable code contains the number of times the line was executed and the actual source code line number. Any line that was not executed will have
#####
in place of the execution count. Blocks that are not executed will have $$$$$
in place of the execution count.The command line option summary for gcov is given below:
-h, –help | Print this help, then exit |
-v, –version | Print version number, then exit |
-a, –all-blocks | Show information for every basic block |
-b, –branch-probabilities | Include branch probabilities in output |
-c, –branch-counts | Given counts of branches taken rather than percentages |
-n, –no-output | Do not create an output file |
-l, –long-file-names | Use long output file names for included source files |
-f, –function-summaries | Output summaries for each function |
-o, –object-directory | DIRFILE Search for object files in DIR or called FILE |
-p, –preserve-paths | Preserve all pathname components |
-u, –unconditional-branches | Show unconditional branch counts |
Visualizing results with LCOV
The Linux testing project (LTP) has come up with a tool called lcov that provides a more user-friendly graphical visualization of the gcov output. It generates html files and integrates well with web based CI systems.
![Primary Primary](/uploads/1/1/9/8/119846030/772735047.png)
To make lcov generate html reports for you, give the following commands once the gcno and gcda files are generated.
lcov --directory . –zerocounters
lcov --directory . --capture --output-file app.info
genhtml app.info
The lcov reports seen from a browser is shown in the screenshots below.
Cross Profiling
This section is adapted from the GCOV manual :
As we have seen so far, running the program to be profiled will cause profile output to be generated. For each source file compiled with the
–coverage
option, a .gcda
file will be generated in the object file directory. This places a restriction that the target system should have the same directory structure. (The program will try to create the needed directory structure, if it is not already present).As per the gnu GCOV documentation, redirection can be done with the help of two execution environment variables.
GCOV_PREFIX
: Contains the prefix to add to the absolute paths in the object file. Prefix can be absolute, or relative. The default is no prefix.GCOV_PREFIX_STRIP
: Indicates the how many initial directory names to strip off the hardwired absolute paths. Default value is0
.
Note: If
GCOV_PREFIX_STRIP
is set without GCOV_PREFIX
is undefined, then a relative path is made out of the hardwired absolute paths.For example, if the object file
/user/build/foo.o
was built with -fprofile-arcs
, the final executable will try to create the data file /user/build/foo.gcda
when running on the target system. This will fail if the corresponding directory does not exist and it is unable to create it. This can be overcome by, for example, setting the environment as GCOV_PREFIX=/target/run
and GCOV_PREFIX_STRIP=1
. Such a setting will name the data file /target/run/build/foo.gcda
.You must move the data files to the expected directory tree in order to use them for profile directed optimizations (
–use-profile
), or to use the gcov tool.Many people share .gcov files without attaching instructions on how to use it. Yet it isn’t evident for everyone which program a .gcov file can be edited, converted or printed with. On this page, we try to provide assistance for handling .gcov files.
1 filename extension(s) found in our database.
.gcov - GNU GCOV Logfile
The GCOV development files are related to GNU GCC. GCOV file is a GNU GCOV Logfile. GCOV is a test coverage program. Use it in concert with GNU CC to analyze your programs to help create more efficient, faster running code. You can use gcov as a profiling tool to help discover where your optimization efforts will best affect your code.
- Application:
- GNU GCC
- Category:
- Development files
- Mime-type:
- text/plain
- Magic:
- - / -
- Aliases:
- -
- GNU GCOV Logfile related extensions:
- .nvb
- NVSG SDK Scene Graph
- .tph
- Turbo Pascal Help
- .jcm
- JECF Java Commerce Message
- .tpy
- TwinCAT PLC Project Variables
- .fce
- ForeUI Custom Element
- .itb
- U-Boot uImage Image Tree Blob
Naturally, other applications may also use the .gcov file extension. Even harmful programs can create .gcov files. Be especially cautious with .gcov files coming from an unknown source!
Can't open a .gcov file?
Gcov For C++
When you double-click a file to open it, Windows examines the filename extension. If Windows recognizes the filename extension, it opens the file in the program that is associated with that filename extension. When Windows does not recognize a filename extension, you receive the following message:
Windows can't open this file:
example.gcov
To open this file, Windows needs to know what program you want to use to open it. Windows can go online to look it up automatically, or you can manually select one from a list of programs that are installed on your computer.
example.gcov
To open this file, Windows needs to know what program you want to use to open it. Windows can go online to look it up automatically, or you can manually select one from a list of programs that are installed on your computer.
To avoid this error, you need to set the file association correctly.
Gcov For Macbook Pro
- Open Control Panel > Control Panel Home > Default Programs > Set Associations.
- Select a file type in the list and click Change Program.
The .gcov file extension is often given incorrectly!
According to the searches on our site, these misspellings were the most common in the past year:
Install Lcov Mac
cov, gco, gcob, gcod, gcv, gov
Is it possible that the filename extension is misspelled?
Similar file extensions in our database:
- .cov
- Fax Cover Page
- .cov
- RFM Covariate Table
- .gcv
- 3D SexVilla Game Movie
- .gov
- Netmino Data
- .gco
- Genbox Family History Chart Options
- .gcob
- TRANSFER Cobol Source Code
Operating systems
DataTypes.net currently supports the following operating systems:
Windows XP/Vista, Windows 7/8, Windows 10, CentOS, Debian GNU/Linux, Ubuntu Linux, FreeBSD, Mac OS X, iOS, Android
If you find the information on this page useful, please feel free to link to this page.
https://datatypes.net/open-gcov-files
If you have useful information about the .gcov file format, then write to us!
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