Ubuntu Manpage: llvm-cov - emit coverage information

NAME

       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.)

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).

-m, --demangled-names
Demangle function names.

-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.

-r Only dump files with relative paths or absolute paths with the prefix specified by
-s.

-s <string>
Source prefix to elide.

-t, --stdout
Print to stdout instead of producing .gcov files.

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

-version
Display the version of llvm-cov.

-x, --hash-filenames
Use md5 hash of file name when naming the coverage output files. The source file
name will be suffixed by ## followed by MD5 hash calculated for it.

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]… [-sources] [SOURCE]…

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 SOURCE….

BIN may be an executable, object file, dynamic library, or archive (thin or otherwise).

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-branches=<VIEW>
Show coverage for branch conditions in terms of either count or percentage. The
supported views are: “count”, “percent”.

-show-line-counts
Show the execution counts for each line. Defaults to true, 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. Defaults to false.

-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. Defaults to
true.

-show-regions
Show the execution counts for each region by displaying a caret that points to the
character where the region starts. Defaults to false.

-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. Defaults to
false.

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

-arch=[*NAMES*]
Specify a list of architectures such that the Nth entry in the list corresponds to
the Nth specified binary. If the covered object is a universal binary, this
specifies 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-allowlist=<FILE>
Show code coverage only for functions listed in the given file. Each line in the
file should start with allowlist_fun:, immediately followed by the name of the
function to accept. This name can be a wildcard expression.

-name-regex=<PATTERN>
Show code coverage only for functions that match the given regular expression.

-ignore-filename-regex=<PATTERN>
Skip source code files with file paths 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.

-compilation-dir=<dir>
Directory used as a base for relative coverage mapping paths. Only applicable when
binaries have been compiled with one of -fcoverage-prefix-map
-fcoverage-compilation-dir, or -ffile-compilation-dir.

-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.

-path-equivalence=<from>,<to>
Map the paths in the coverage data to local source file paths. This allows you to
generate the coverage data on one machine, and then use llvm-cov on a different
machine where you have the same files on a different path.

-coverage-watermark=<high>,<low>
Set high and low watermarks for coverage in html format output. This allows you to
set the high and low watermark of coverage as desired, green when coverage >= high,
red when coverage < low, and yellow otherwise. Both high and low should be between
0-100 and high > low.

-debuginfod

Use debuginfod to look up coverage mapping for binary IDs present in the profile but not
in any object given on the command line. Defaults to true if debuginfod is compiled in and
configured via the DEBUGINFOD_URLS environment variable.

-debug-file-directory=<dir>

Provides local directories to search for objects corresponding to binary IDs in the
profile (as with debuginfod). Defaults to system build ID directories.

REPORT COMMAND

SYNOPSIS
llvm-cov report [options] -instr-profile PROFILE [BIN] [-object BIN]… [-sources] [SOURCE]…

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 SOURCE….

BIN may be an executable, object file, dynamic library, or archive (thin or otherwise).

If no source files are provided, a summary line is printed for each file in the coverage
data. If any files are provided, summaries can be shown for each function in the listed
files if the -show-functions option is enabled.

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-region-summary
Show statistics for all regions. Defaults to true.

-show-branch-summary
Show statistics for all branch conditions. Defaults to true.

-show-functions
Show coverage summaries for each function. Defaults to false.

-show-instantiation-summary
Show statistics for all function instantiations. Defaults to false.

-ignore-filename-regex=<PATTERN>
Skip source code files with file paths that match the given regular expression.

-debuginfod

Attempt to look up coverage mapping from objects using debuginfod. This is attempted by
default for binary IDs present in the profile but not provided on the command line, so
long as debuginfod is compiled in and configured via DEBUGINFOD_URLS.

-debug-file-directory=<dir>

Provides a directory to search for objects corresponding to binary IDs in the profile.

EXPORT COMMAND

SYNOPSIS
llvm-cov export [options] -instr-profile PROFILE [BIN] [-object BIN]… [-sources] [SOURCE]…

DESCRIPTION
The llvm-cov export command exports coverage data of the binaries BIN… using the profile
data PROFILE in either JSON or lcov trace file format.

When exporting JSON, the regions, functions, branches, expansions, and summaries of the
coverage data will be exported. When exporting an lcov trace file, the line-based
coverage, branch coverage, and summaries will be exported.

The exported data can optionally be filtered to only export the coverage for the files
listed in SOURCE….

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.

-format=<FORMAT>
Use the specified output format. The supported formats are: “text” (JSON), “lcov”.

-summary-only
Export only summary information for each file in the coverage data. This mode will
not export coverage information for smaller units such as individual functions or
regions. The result will contain the same information as produced by the llvm-cov
report command, but presented in JSON or lcov format rather than text.

-ignore-filename-regex=<PATTERN>
Skip source code files with file paths that match the given regular expression.

-skip-expansions

Skip exporting macro expansion coverage data.

-skip-functions

Skip exporting per-function coverage data.

-num-threads=N, -j=N

Use N threads to export coverage data. When N=0, llvm-cov auto-detects an
appropriate number of threads to use. This is the default.

-debuginfod

-debug-file-directory=<dir>

Provides a directory to search for objects corresponding to binary IDs in the profile.

AUTHOR

       Maintained by the LLVM Team (https://llvm.org/).

COPYRIGHT

       2003-2023, LLVM Project