Provided by: llvm-21_21.1.2-2ubuntu6_amd64 
NAME
lit - LLVM Integrated Tester
SYNOPSIS
lit [options] [tests]
DESCRIPTION
lit is a portable tool for executing LLVM and Clang style test suites, summarizing their results, and
providing indication of failures. lit is designed to be a lightweight testing tool with as simple a user
interface as possible.
lit should be run with one or more tests to run specified on the command line. Tests can be either
individual test files or directories to search for tests (see TEST DISCOVERY).
Each specified test will be executed (potentially concurrently) and once all tests have been run lit will
print summary information on the number of tests which passed or failed (see TEST STATUS RESULTS). The
lit program will execute with a non-zero exit code if any tests fail.
By default lit will use a succinct progress display and will only print summary information for test
failures. See OUTPUT OPTIONS for options controlling the lit progress display and output.
lit also includes a number of options for controlling how tests are executed (specific features may
depend on the particular test format). See EXECUTION OPTIONS for more information.
Finally, lit also supports additional options for only running a subset of the options specified on the
command line, see SELECTION OPTIONS for more information.
lit parses options from the environment variable LIT_OPTS after parsing options from the command line.
LIT_OPTS is primarily useful for supplementing or overriding the command-line options supplied to lit by
check targets defined by a project’s build system.
lit can also read options from response files which are specified as inputs using the @path/to/file.rsp
syntax. Arguments read from a file must be one per line and are treated as if they were in the same place
as the original file referencing argument on the command line. A response file can reference other
response files.
Users interested in the lit architecture or designing a lit testing implementation should see LIT
INFRASTRUCTURE.
GENERAL OPTIONS
-h, --help
Show the lit help message and exit.
--version
Show lit’s version number and exit.
-j N, --workers N
Run N tests in parallel. By default, this is automatically chosen to match the number of detected
available CPUs.
--config-prefix NAME
Search for NAME.cfg and NAME.site.cfg when searching for test suites, instead of lit.cfg and
lit.site.cfg.
-D NAME[=VALUE], --param NAME[=VALUE]
Add a user defined parameter NAME with the given VALUE (or the empty string if not given). The
meaning and use of these parameters is test suite dependent.
OUTPUT OPTIONS
-q, --quiet
Suppress any output except for test failures.
-s, --succinct
Show less output, for example don’t show information on tests that pass. Also show a progress
bar, unless --no-progress-bar is specified.
-v, --verbose
Show more information on test failures, for example the entire test output instead of just the
test result.
Each command is printed before it is executed. This can be valuable for debugging test failures,
as the last printed command is the one that failed. Moreover, lit inserts 'RUN: at line N' after
each command pipeline in the output to help you locate the source line of the failed command.
-vv, --echo-all-commands
Deprecated alias for -v.
-a, --show-all
Enable -v, but for all tests not just failed tests.
-o PATH, --output PATH
Write test results to the provided path.
--no-progress-bar
Do not use curses based progress bar.
--show-excluded
Show excluded tests.
--show-skipped
Show skipped tests.
--show-unsupported
Show unsupported tests.
--show-pass
Show passed tests.
--show-flakypass
Show passed with retry tests.
--show-xfail
Show expectedly failed tests.
EXECUTION OPTIONS
--gtest-sharding
Enable sharding for GoogleTest format.
--no-gtest-sharding
Disable sharding for GoogleTest format.
--path PATH
Specify an additional PATH to use when searching for executables in tests.
--vg Run individual tests under valgrind (using the memcheck tool). The --error-exitcode argument for
valgrind is used so that valgrind failures will cause the program to exit with a non-zero status.
When this option is enabled, lit will also automatically provide a “valgrind” feature that can be
used to conditionally disable (or expect failure in) certain tests.
--vg-leak
When --vg is used, enable memory leak checks. When this option is enabled, lit will also
automatically provide a “vg_leak” feature that can be used to conditionally disable (or expect
failure in) certain tests.
--vg-arg ARG
When --vg is used, specify an additional argument to pass to valgrind itself.
--no-execute
Don’t execute any tests (assume that they pass).
--xunit-xml-output XUNIT_XML_OUTPUT
Write XUnit-compatible XML test reports to the specified file.
--report-failures-only
Only include failures (see TEST STATUS RESULTS) in the report.
--resultdb-output RESULTDB_OUTPUT
Write LuCI ResultDB compatible JSON to the specified file.
--time-trace-output TIME_TRACE_OUTPUT
Write Chrome tracing compatible JSON to the specified file
--timeout MAXINDIVIDUALTESTTIME
Maximum time to spend running a single test (in seconds). 0 means no time limit. [Default: 0]
--timeout N
Spend at most N seconds (approximately) running each individual test. 0 means no time limit, and
0 is the default. Note that this is not an alias for --max-time; the two are different kinds of
maximums.
--max-failures MAX_FAILURES
Stop execution after the given number of failures.
--max-retries-per-test N
Retry running failed tests at most N times. Out of the following options to rerun failed tests
the --max-retries-per-test is the only one that doesn’t require a change in the test scripts or
the test config:
• --max-retries-per-test lit option
• config.test_retry_attempts test suite option
• ALLOW_RETRIES: annotation in test script
Any option in the list above overrules its predecessor.
--allow-empty-runs
Do not fail the run if all tests are filtered out.
--per-test-coverage
Emit the necessary test coverage data, divided per test case (involves setting a unique value to
LLVM_PROFILE_FILE for each RUN). The coverage data files will be emitted in the directory
specified by config.test_exec_root.
--ignore-fail
Exit with status zero even if some tests fail.
--skip-test-time-recording
Do not track elapsed wall time for each test.
--time-tests
Track the wall time individual tests take to execute and includes the results in the summary
output. This is useful for determining which tests in a test suite take the most time to execute.
SELECTION OPTIONS
By default, lit will run failing tests first, then run tests in descending execution time order to
optimize concurrency. The execution order can be changed using the --order option.
The timing data is stored in the test_exec_root in a file named .lit_test_times.txt. If this file does
not exist, then lit checks the test_source_root for the file to optionally accelerate clean builds.
--max-tests N
Run at most N tests and then terminate.
--max-time N
Spend at most N seconds (approximately) running tests and then terminate. Note that this is not
an alias for --timeout; the two are different kinds of maximums.
--order {lexical,random,smart}
Define the order in which tests are run. The supported values are:
• lexical - tests will be run in lexical order according to the test file path. This option is
useful when predictable test order is desired.
• random - tests will be run in random order.
• smart - tests that failed previously will be run first, then the remaining tests, all in
descending execution time order. This is the default as it optimizes concurrency.
--shuffle
Run the tests in a random order, not failing/slowest first. Deprecated, use --order instead.
-i, --incremental
Run failed tests first (DEPRECATED: use --order=smart).
--filter REGEXP
Run only those tests whose name matches the regular expression specified in REGEXP. The
environment variable LIT_FILTER can be also used in place of this option, which is especially
useful in environments where the call to lit is issued indirectly.
--filter-out REGEXP
Filter out those tests whose name matches the regular expression specified in REGEXP. The
environment variable LIT_FILTER_OUT can be also used in place of this option, which is especially
useful in environments where the call to lit is issued indirectly.
--xfail LIST
Treat those tests whose name is in the semicolon separated list LIST as XFAIL. This can be helpful
when one does not want to modify the test suite. The environment variable LIT_XFAIL can be also
used in place of this option, which is especially useful in environments where the call to lit is
issued indirectly.
A test name can specified as a file name relative to the test suite directory. For example:
LIT_XFAIL="affinity/kmp-hw-subset.c;offloading/memory_manager.cpp"
In this case, all of the following tests are treated as XFAIL:
libomp :: affinity/kmp-hw-subset.c
libomptarget :: nvptx64-nvidia-cuda :: offloading/memory_manager.cpp
libomptarget :: x86_64-pc-linux-gnu :: offloading/memory_manager.cpp
Alternatively, a test name can be specified as the full test name reported in LIT output. For
example, we can adjust the previous example not to treat the nvptx64-nvidia-cuda version of
offloading/memory_manager.cpp as XFAIL:
LIT_XFAIL="affinity/kmp-hw-subset.c;libomptarget :: x86_64-pc-linux-gnu :: offloading/memory_manager.cpp"
--xfail-not LIST
Do not treat the specified tests as XFAIL. The environment variable LIT_XFAIL_NOT can also be
used in place of this option. The syntax is the same as for --xfail and LIT_XFAIL. --xfail-not
and LIT_XFAIL_NOT always override all other XFAIL specifications, including an --xfail appearing
later on the command line. The primary purpose is to suppress an XPASS result without modifying a
test case that uses the XFAIL directive.
--num-shards M
Divide the set of selected tests into M equal-sized subsets or “shards”, and run only one of them.
Must be used with the --run-shard=N option, which selects the shard to run. The environment
variable LIT_NUM_SHARDS can also be used in place of this option. These two options provide a
coarse mechanism for partitioning large testsuites, for parallel execution on separate machines
(say in a large testing farm).
--run-shard N
Select which shard to run, assuming the --num-shards=M option was provided. The two options must
be used together, and the value of N must be in the range 1..M. The environment variable
LIT_RUN_SHARD can also be used in place of this option.
ADDITIONAL OPTIONS
--debug
Run lit in debug mode, for debugging configuration issues and lit itself.
--show-suites
List the discovered test suites and exit.
--show-tests
List all of the discovered tests and exit.
--show-used-features
Show all features used in the test suite (in XFAIL, UNSUPPORTED and REQUIRES) and exit.
EXIT STATUS
lit will exit with an exit code of 1 if there are any failures (see TEST STATUS RESULTS) and
--ignore-fail has not been passed. Otherwise, it will exit with the status 0. Other exit codes are used
for non-test related failures (for example a user error or an internal program error).
TEST DISCOVERY
The inputs passed to lit can be either individual tests, or entire directories or hierarchies of tests to
run. When lit starts up, the first thing it does is convert the inputs into a complete list of tests to
run as part of test discovery.
In the lit model, every test must exist inside some test suite. lit resolves the inputs specified on the
command line to test suites by searching upwards from the input path until it finds a lit.cfg or
lit.site.cfg file. These files serve as both a marker of test suites and as configuration files which
lit loads in order to understand how to find and run the tests inside the test suite.
Once lit has mapped the inputs into test suites it traverses the list of inputs adding tests for
individual files and recursively searching for tests in directories.
This behavior makes it easy to specify a subset of tests to run, while still allowing the test suite
configuration to control exactly how tests are interpreted. In addition, lit always identifies tests by
the test suite they are in, and their relative path inside the test suite. For appropriately configured
projects, this allows lit to provide convenient and flexible support for out-of-tree builds.
TEST STATUS RESULTS
Each test ultimately produces one of the following eight results:
PASS
The test succeeded.
FLAKYPASS
The test succeeded after being re-run more than once. This only applies to tests containing an
ALLOW_RETRIES: annotation.
XFAIL
The test failed, but that is expected. This is used for test formats which allow specifying that a
test does not currently work, but wish to leave it in the test suite.
XPASS
The test succeeded, but it was expected to fail. This is used for tests which were specified as
expected to fail, but are now succeeding (generally because the feature they test was broken and has
been fixed).
FAIL
The test failed.
UNRESOLVED
The test result could not be determined. For example, this occurs when the test could not be run, the
test itself is invalid, or the test was interrupted.
UNSUPPORTED
The test is not supported in this environment. This is used by test formats which can report
unsupported tests.
TIMEOUT
The test was run, but it timed out before it was able to complete.
Unresolved (UNRESOLVED), timed out (TIMEOUT), failed (FAIL) and unexpectedly passed (XPASS) tests are
considered failures.
Depending on the test format tests may produce additional information about their status (generally only
for failures). See the OUTPUT OPTIONS section for more information.
LIT INFRASTRUCTURE
This section describes the lit testing architecture for users interested in creating a new lit testing
implementation, or extending an existing one.
lit proper is primarily an infrastructure for discovering and running arbitrary tests, and to expose a
single convenient interface to these tests. lit itself doesn’t know how to run tests, rather this logic
is defined by test suites.
TEST SUITES
As described in TEST DISCOVERY, tests are always located inside a test suite. Test suites serve to
define the format of the tests they contain, the logic for finding those tests, and any additional
information to run the tests.
lit identifies test suites as directories containing lit.cfg or lit.site.cfg files (see also
--config-prefix). Test suites are initially discovered by recursively searching up the directory
hierarchy for all the input files passed on the command line. You can use --show-suites to display the
discovered test suites at startup.
Once a test suite is discovered, its config file is loaded. Config files themselves are Python modules
which will be executed. When the config file is executed, two important global variables are predefined:
lit_config
The global lit configuration object (a LitConfig instance), which defines the builtin test formats,
global configuration parameters, and other helper routines for implementing test configurations.
config
This is the config object (a TestingConfig instance) for the test suite, which the config file is
expected to populate. The following variables are also available on the config object, some of which
must be set by the config and others are optional or predefined:
name [required] The name of the test suite, for use in reports and diagnostics.
test_format [required] The test format object which will be used to discover and run tests in the test
suite. Generally this will be a builtin test format available from the lit.formats module.
test_source_root The filesystem path to the test suite root. For out-of-dir builds this is the
directory that will be scanned for tests.
test_exec_root For out-of-dir builds, the path to the test suite root inside the object directory.
This is where tests will be run and temporary output files placed.
environment A dictionary representing the environment to use when executing tests in the suite.
standalone_tests When true, mark a directory with tests expected to be run standalone. Test discovery
is disabled for that directory. lit.suffixes and lit.excludes must be empty when this variable is
true.
suffixes For lit test formats which scan directories for tests, this variable is a list of suffixes to
identify test files. Used by: ShTest.
substitutions For lit test formats which substitute variables into a test script, the list of
substitutions to perform. Used by: ShTest.
unsupported Mark an unsupported directory, all tests within it will be reported as unsupported. Used
by: ShTest.
parent The parent configuration, this is the config object for the directory containing the test
suite, or None.
root The root configuration. This is the top-most lit configuration in the project.
pipefail Normally a test using a shell pipe fails if any of the commands on the pipe fail. If this is
not desired, setting this variable to false makes the test fail only if the last command in the pipe
fails.
available_features A set of features that can be used in XFAIL, REQUIRES, and UNSUPPORTED directives.
TEST DISCOVERY
Once test suites are located, lit recursively traverses the source directory (following test_source_root)
looking for tests. When lit enters a sub-directory, it first checks to see if a nested test suite is
defined in that directory. If so, it loads that test suite recursively, otherwise it instantiates a
local test config for the directory (see LOCAL CONFIGURATION FILES).
Tests are identified by the test suite they are contained within, and the relative path inside that
suite. Note that the relative path may not refer to an actual file on disk; some test formats (such as
GoogleTest) define “virtual tests” which have a path that contains both the path to the actual test file
and a subpath to identify the virtual test.
LOCAL CONFIGURATION FILES
When lit loads a subdirectory in a test suite, it instantiates a local test configuration by cloning the
configuration for the parent directory — the root of this configuration chain will always be a test
suite. Once the test configuration is cloned lit checks for a lit.local.cfg file in the subdirectory.
If present, this file will be loaded and can be used to specialize the configuration for each individual
directory. This facility can be used to define subdirectories of optional tests, or to change other
configuration parameters — for example, to change the test format, or the suffixes which identify test
files.
SUBSTITUTIONS
lit allows patterns to be substituted inside RUN commands. It also provides the following base set of
substitutions, which are defined in TestRunner.py:
┌─────────────────────────┬───────────────────────────────────────┐
│ Macro │ Substitution │
├─────────────────────────┼───────────────────────────────────────┤
│ %s │ source path (path to the file │
│ │ currently being run) │
├─────────────────────────┼───────────────────────────────────────┤
│ %S │ source dir (directory of the file │
│ │ currently being run) │
├─────────────────────────┼───────────────────────────────────────┤
│ %p │ same as %S │
├─────────────────────────┼───────────────────────────────────────┤
│ %{pathsep} │ path separator │
├─────────────────────────┼───────────────────────────────────────┤
│ %{fs-src-root} │ root component of file system paths │
│ │ pointing to the LLVM checkout │
├─────────────────────────┼───────────────────────────────────────┤
│ %{fs-tmp-root} │ root component of file system paths │
│ │ pointing to the test’s temporary │
│ │ directory │
├─────────────────────────┼───────────────────────────────────────┤
│ %{fs-sep} │ file system path separator │
├─────────────────────────┼───────────────────────────────────────┤
│ %t │ temporary file name unique to the │
│ │ test │
├─────────────────────────┼───────────────────────────────────────┤
│ %basename_t │ The last path component of %t but │
│ │ without the .tmp extension │
│ │ (deprecated, use %{t:stem} instead) │
├─────────────────────────┼───────────────────────────────────────┤
│ %T │ parent directory of %t (not unique, │
│ │ deprecated, do not use) │
├─────────────────────────┼───────────────────────────────────────┤
│ %% │ % │
├─────────────────────────┼───────────────────────────────────────┤
│ %/s │ %s but \ is replaced by / │
├─────────────────────────┼───────────────────────────────────────┤
│ %/S │ %S but \ is replaced by / │
├─────────────────────────┼───────────────────────────────────────┤
│ %/p │ %p but \ is replaced by / │
├─────────────────────────┼───────────────────────────────────────┤
│ %/t │ %t but \ is replaced by / │
├─────────────────────────┼───────────────────────────────────────┤
│ %/T │ %T but \ is replaced by / │
├─────────────────────────┼───────────────────────────────────────┤
│ %{s:basename} │ The last path component of %s │
├─────────────────────────┼───────────────────────────────────────┤
│ %{t:stem} │ The last path component of %t but │
│ │ without the .tmp extension (alias for │
│ │ %basename_t) │
├─────────────────────────┼───────────────────────────────────────┤
│ %{s:real} │ %s after expanding all symbolic links │
│ │ and substitute drives │
├─────────────────────────┼───────────────────────────────────────┤
│ %{S:real} │ %S after expanding all symbolic links │
│ │ and substitute drives │
├─────────────────────────┼───────────────────────────────────────┤
│ %{p:real} │ %p after expanding all symbolic links │
│ │ and substitute drives │
├─────────────────────────┼───────────────────────────────────────┤
│ %{t:real} │ %t after expanding all symbolic links │
│ │ and substitute drives │
├─────────────────────────┼───────────────────────────────────────┤
│ %{T:real} │ %T after expanding all symbolic links │
│ │ and substitute drives │
├─────────────────────────┼───────────────────────────────────────┤
│ %{/s:real} │ %/s after expanding all symbolic │
│ │ links and substitute drives │
├─────────────────────────┼───────────────────────────────────────┤
│ %{/S:real} │ %/S after expanding all symbolic │
│ │ links and substitute drives │
├─────────────────────────┼───────────────────────────────────────┤
│ %{/p:real} │ %/p after expanding all symbolic │
│ │ links and substitute drives │
├─────────────────────────┼───────────────────────────────────────┤
│ %{/t:real} │ %/t after expanding all symbolic │
│ │ links and substitute drives │
├─────────────────────────┼───────────────────────────────────────┤
│ %{/T:real} │ %/T after expanding all symbolic │
│ │ links and substitute drives │
├─────────────────────────┼───────────────────────────────────────┤
│ %{/s:regex_replacement} │ %/s but escaped for use in the │
│ │ replacement of a s@@@ command in sed │
├─────────────────────────┼───────────────────────────────────────┤
│ %{/S:regex_replacement} │ %/S but escaped for use in the │
│ │ replacement of a s@@@ command in sed │
├─────────────────────────┼───────────────────────────────────────┤
│ %{/p:regex_replacement} │ %/p but escaped for use in the │
│ │ replacement of a s@@@ command in sed │
├─────────────────────────┼───────────────────────────────────────┤
│ %{/t:regex_replacement} │ %/t but escaped for use in the │
│ │ replacement of a s@@@ command in sed │
├─────────────────────────┼───────────────────────────────────────┤
│ %{/T:regex_replacement} │ %/T but escaped for use in the │
│ │ replacement of a s@@@ command in sed │
├─────────────────────────┼───────────────────────────────────────┤
│ %:s │ On Windows, %/s but a : is removed if │
│ │ its the second character. Otherwise, │
│ │ %s but with a single leading / │
│ │ removed. │
├─────────────────────────┼───────────────────────────────────────┤
│ %:S │ On Windows, %/S but a : is removed if │
│ │ its the second character. Otherwise, │
│ │ %S but with a single leading / │
│ │ removed. │
├─────────────────────────┼───────────────────────────────────────┤
│ %:p │ On Windows, %/p but a : is removed if │
│ │ its the second character. Otherwise, │
│ │ %p but with a single leading / │
│ │ removed. │
├─────────────────────────┼───────────────────────────────────────┤
│ %:t │ On Windows, %/t but a : is removed if │
│ │ its the second character. Otherwise, │
│ │ %t but with a single leading / │
│ │ removed. │
├─────────────────────────┼───────────────────────────────────────┤
│ %:T │ On Windows, %/T but a : is removed if │
│ │ its the second character. Otherwise, │
│ │ %T but with a single leading / │
│ │ removed. │
└─────────────────────────┴───────────────────────────────────────┘
Other substitutions are provided that are variations on this base set and further substitution patterns
can be defined by each test module. See the modules LOCAL CONFIGURATION FILES.
More detailed information on substitutions can be found in the LLVM Testing Infrastructure Guide.
TEST RUN OUTPUT FORMAT
The lit output for a test run conforms to the following schema, in both short and verbose modes (although
in short mode no PASS lines will be shown). This schema has been chosen to be relatively easy to
reliably parse by a machine (for example in buildbot log scraping), and for other tools to generate.
Each test result is expected to appear on a line that matches:
<result code>: <test name> (<progress info>)
where <result-code> is a standard test result such as PASS, FAIL, XFAIL, XPASS, UNRESOLVED, or
UNSUPPORTED. The performance result codes of IMPROVED and REGRESSED are also allowed.
The <test name> field can consist of an arbitrary string containing no newline.
The <progress info> field can be used to report progress information such as (1/300) or can be empty, but
even when empty the parentheses are required.
Should a test be allowed retries (see ALLOW_RETRIES: annotation) and it needed more than one attempt to
succeed, then <progress info> is extended by this information:
, <num_attempts_made> of <max_allowed_attempts> attempts
Each test result may include additional (multiline) log information in the following format:
<log delineator> TEST '(<test name>)' <trailing delineator>
... log message ...
<log delineator>
where <test name> should be the name of a preceding reported test, <log delineator> is a string of “*”
characters at least four characters long (the recommended length is 20), and <trailing delineator> is an
arbitrary (unparsed) string.
The following is an example of a test run output which consists of four tests A, B, C, and D, and a log
message for the failing test C:
PASS: A (1 of 4)
PASS: B (2 of 4)
FAIL: C (3 of 4)
******************** TEST 'C' FAILED ********************
Test 'C' failed as a result of exit code 1.
********************
PASS: D (4 of 4)
DEFAULT FEATURES
For convenience lit automatically adds available_features for some common use cases.
lit adds a feature based on the operating system being built on, for example: system-darwin,
system-linux, etc. lit also automatically adds a feature based on the current architecture, for example
target-x86_64, target-aarch64, etc.
When building with sanitizers enabled, lit automatically adds the short name of the sanitizer, for
example: asan, tsan, etc.
To see the full list of features that can be added, see llvm/utils/lit/lit/llvm/config.py.
LIT EXAMPLE TESTS
The lit distribution contains several example implementations of test suites in the ExampleTests
directory.
SEE ALSO
valgrind(1)
AUTHOR
Maintained by the LLVM Team (https://llvm.org/).
COPYRIGHT
2003-2025, LLVM Project
15 2025-09-26 LIT(1)