llvm-cov - emit coverage information — LLVM 5 documentation

# llvm-cov - emit coverage information

## SYNOPSIS

llvm-cov command [args…]

## DESCRIPTION

The llvm-cov tool shows code coverage information for programs that are instrumented to emit profile data. It can be used to work with `gcov`-style coverage or with `clang`’s instrumentation based profiling.

If the program is invoked with a base name of `gcov`, it will behave as if the llvm-cov gcov command were called. Otherwise, a command should be provided.

## COMMANDS

- gcov
- show
- report
- export

## GCOV COMMAND

### SYNOPSIS

llvm-cov gcov [options] SOURCEFILE

### DESCRIPTION

The llvm-cov gcov tool reads code coverage data files and displays the coverage information for a specified source file. It is compatible with the `gcov` tool from version 4.2 of `GCC` and may also be compatible with some later versions of `gcov`.

To use llvm-cov gcov, you must first build an instrumented version of your application that collects coverage data as it runs. Compile with the `-fprofile-arcs` and `-ftest-coverage` options to add the instrumentation. (Alternatively, you can use the `--coverage` option, which includes both of those other options.) You should compile with debugging information (`-g`) and without optimization (`-O0`); otherwise, the coverage data cannot be accurately mapped back to the source code.

At the time you compile the instrumented code, a `.gcno` data file will be generated for each object file. These `.gcno` files contain half of the coverage data. The other half of the data comes from `.gcda` files that are generated when you run the instrumented program, with a separate `.gcda` file for each object file. Each time you run the program, the execution counts are summed into any existing `.gcda` files, so be sure to remove any old files if you do not want their contents to be included.

By default, the `.gcda` files are written into the same directory as the object files, but you can override that by setting the `GCOV_PREFIX` and `GCOV_PREFIX_STRIP` environment variables. The `GCOV_PREFIX_STRIP` variable specifies a number of directory components to be removed from the start of the absolute path to the object file directory. After stripping those directories, the prefix from the `GCOV_PREFIX` variable is added. These environment variables allow you to run the instrumented program on a machine where the original object file directories are not accessible, but you will then need to copy the `.gcda` files back to the object file directories where llvm-cov gcov expects to find them.

Once you have generated the coverage data files, run llvm-cov gcov for each main source file where you want to examine the coverage results. This should be run from the same directory where you previously ran the compiler. The results for the specified source file are written to a file named by appending a `.gcov` suffix. A separate output file is also created for each file included by the main source file, also with a `.gcov` suffix added.

The basic content of an `.gcov` output file is a copy of the source file with an execution count and line number prepended to every line. The execution count is shown as `-` if a line does not contain any executable code. If a line contains code but that code was never executed, the count is displayed as `#####`.

### OPTIONS

`-a````,` `--all-blocks```

  Display all basic blocks. If there are multiple blocks for a single line of source code, this option causes llvm-cov to show the count for each block instead of just one count for the entire line.

`-b````,` `--branch-probabilities```

  Display conditional branch probabilities and a summary of branch information.

`-c````,` `--branch-counts```

  Display branch counts instead of probabilities (requires -b).

`-f````,` `--function-summaries```

  Show a summary of coverage for each function instead of just one summary for an entire source file.

`--help```

  Display available options (–help-hidden for more).

`-l````,` `--long-file-names```

  For coverage output of files included from the main source file, add the main file name followed by `##` as a prefix to the output file names. This can be combined with the –preserve-paths option to use complete paths for both the main file and the included file.

`-n````,` `--no-output```

  Do not output any `.gcov` files. Summary information is still displayed.

`-o``=<DIR|FILE>``,` `--object-directory``=<DIR>``,` `--object-file``=<FILE>`

  Find objects in DIR or based on FILE’s path. If you specify a particular object file, the coverage data files are expected to have the same base name with `.gcno` and `.gcda` extensions. If you specify a directory, the files are expected in that directory with the same base name as the source file.

`-p````,` `--preserve-paths```

  Preserve path components when naming the coverage output files. In addition to the source file name, include the directories from the path to that file. The directories are separate by `#` characters, with `.` directories removed and `..` directories replaced by `^` characters. When used with the –long-file-names option, this applies to both the main file name and the included file name.

`-u````,` `--unconditional-branches```

  Include unconditional branches in the output for the –branch-probabilities option.

`-version```

  Display the version of llvm-cov.

### EXIT STATUS

llvm-cov gcov returns 1 if it cannot read input files. Otherwise, it exits with zero.

## SHOW COMMAND

### SYNOPSIS

llvm-cov show [options] -instr-profile PROFILE BIN [-object BIN,…] [[-object BIN]] [SOURCES]

### DESCRIPTION

The llvm-cov show command shows line by line coverage of the binaries BIN,… using the profile data PROFILE. It can optionally be filtered to only show the coverage for the files listed in SOURCES.

To use llvm-cov show, you need a program that is compiled with instrumentation to emit profile and coverage data. To build such a program with `clang` use the `-fprofile-instr-generate` and `-fcoverage-mapping` flags. If linking with the `clang` driver, pass `-fprofile-instr-generate` to the link stage to make sure the necessary runtime libraries are linked in.

The coverage information is stored in the built executable or library itself, and this is what you should pass to llvm-cov show as a BIN argument. The profile data is generated by running this instrumented program normally. When the program exits it will write out a raw profile file, typically called `default.profraw`, which can be converted to a format that is suitable for the PROFILE argument using the llvm-profdata merge tool.

### OPTIONS

`-show-line-counts```

  Show the execution counts for each line. This is enabled by default, unless another `-show` option is used.

`-show-expansions```

  Expand inclusions, such as preprocessor macros or textual inclusions, inline in the display of the source file.

`-show-instantiations```

  For source regions that are instantiated multiple times, such as templates in `C++`, show each instantiation separately as well as the combined summary.

`-show-regions```

  Show the execution counts for each region by displaying a caret that points to the character where the region starts.

`-show-line-counts-or-regions```

  Show the execution counts for each line if there is only one region on the line, but show the individual regions if there are multiple on the line.

`-use-color[``=VALUE]`

  Enable or disable color output. By default this is autodetected.

`-arch``=<name>`

  If the covered binary is a universal binary, select the architecture to use. It is an error to specify an architecture that is not included in the universal binary or to use an architecture that does not match a non-universal binary.

`-name``=<NAME>`

  Show code coverage only for functions with the given name.

`-name-regex``=<PATTERN>`

  Show code coverage only for functions that match the given regular expression.

`-format``=<FORMAT>`

  Use the specified output format. The supported formats are: “text”, “html”.

`-tab-size``=<TABSIZE>`

  Replace tabs with <TABSIZE> spaces when preparing reports. Currently, this is only supported for the html format.

`-output-dir``=PATH`

  Specify a directory to write coverage reports into. If the directory does not exist, it is created. When used in function view mode (i.e when -name or -name-regex are used to select specific functions), the report is written to PATH/functions.EXTENSION. When used in file view mode, a report for each file is written to PATH/REL_PATH_TO_FILE.EXTENSION.

`-Xdemangler``=<TOOL>|<TOOL-OPTION>`

  Specify a symbol demangler. This can be used to make reports more human-readable. This option can be specified multiple times to supply arguments to the demangler (e.g -Xdemangler c++filt -Xdemangler -n for C++). The demangler is expected to read a newline-separated list of symbols from stdin and write a newline-separated list of the same length to stdout.

`-num-threads``=N``,` `-j``=N`

  Use N threads to write file reports (only applicable when -output-dir is specified). When N=0, llvm-cov auto-detects an appropriate number of threads to use. This is the default.

`-line-coverage-gt``=<N>`

  Show code coverage only for functions with line coverage greater than the given threshold.

`-line-coverage-lt``=<N>`

  Show code coverage only for functions with line coverage less than the given threshold.

`-region-coverage-gt``=<N>`

  Show code coverage only for functions with region coverage greater than the given threshold.

`-region-coverage-lt``=<N>`

  Show code coverage only for functions with region coverage less than the given threshold.

## REPORT COMMAND

### SYNOPSIS

llvm-cov report [options] -instr-profile PROFILE BIN [-object BIN,…] [[-object BIN]] [SOURCES]

### DESCRIPTION

The llvm-cov report command displays a summary of the coverage of the binaries BIN,… using the profile data PROFILE. It can optionally be filtered to only show the coverage for the files listed in SOURCES.

If no source files are provided, a summary line is printed for each file in the coverage data. If any files are provided, summaries are shown for each function in the listed files instead.

For information on compiling programs for coverage and generating profile data, see SHOW COMMAND.

### OPTIONS

`-use-color[``=VALUE]`

  Enable or disable color output. By default this is autodetected.

`-arch``=<name>`

  If the covered binary is a universal binary, select the architecture to use. It is an error to specify an architecture that is not included in the universal binary or to use an architecture that does not match a non-universal binary.

`-show-functions```

  Show coverage summaries for each function.

## EXPORT COMMAND

### SYNOPSIS

llvm-cov export [options] -instr-profile PROFILE BIN [-object BIN,…] [[-object BIN]]

### DESCRIPTION

The llvm-cov export command exports regions, functions, expansions, and summaries of the coverage of the binaries BIN,… using the profile data PROFILE as JSON.

For information on compiling programs for coverage and generating profile data, see SHOW COMMAND.

### OPTIONS

`-arch``=<name>`

  If the covered binary is a universal binary, select the architecture to use. It is an error to specify an architecture that is not included in the universal binary or to use an architecture that does not match a non-universal binary.