llvm-cov - emit coverage information
SYNOPSIS
:program:`llvm-cov` command [args...]
DESCRIPTION
The :program:`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 :program:`llvm-cov gcov` command were called. Otherwise, a command should
be provided.
COMMANDS
- :ref:`gcov <llvm-cov-gcov>`
- :ref:`show <llvm-cov-show>`
- :ref:`report <llvm-cov-report>`
- :ref:`export <llvm-cov-export>`
GCOV COMMAND
SYNOPSIS
:program:`llvm-cov gcov` [options] SOURCEFILE
DESCRIPTION
The :program:`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 :program:`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 :program:`llvm-cov gcov` expects to find them.
Once you have generated the coverage data files, run :program:`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
EXIT STATUS
:program:`llvm-cov gcov` returns 1 if it cannot read input files. Otherwise, it exits with zero.
SHOW COMMAND
SYNOPSIS
:program:`llvm-cov show` [options] -instr-profile PROFILE BIN [-object BIN,...] [[-object BIN]] [SOURCES]
DESCRIPTION
The :program:`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.
BIN may be an executable, object file, dynamic library, or archive (thin or otherwise).
To use :program:`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 :program:`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 :program:`llvm-profdata merge`
tool.
OPTIONS
REPORT COMMAND
SYNOPSIS
:program:`llvm-cov report` [options] -instr-profile PROFILE BIN [-object BIN,...] [[-object BIN]] [SOURCES]
DESCRIPTION
The :program:`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.
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 :ref:`llvm-cov-show`.
OPTIONS
EXPORT COMMAND
SYNOPSIS
:program:`llvm-cov export` [options] -instr-profile PROFILE BIN [-object BIN,...] [[-object BIN]] [SOURCES]
DESCRIPTION
The :program:`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, expansions, and summaries of the coverage data will be exported. When exporting an lcov trace file, the line-based coverage and summaries will be exported.
The exported data can optionally be filtered to only export the coverage for the files listed in SOURCES.
For information on compiling programs for coverage and generating profile data, see :ref:`llvm-cov-show`.