forked from OSchip/llvm-project
264 lines
9.4 KiB
ReStructuredText
264 lines
9.4 KiB
ReStructuredText
==============
|
|
Testing libc++
|
|
==============
|
|
|
|
.. contents::
|
|
:local:
|
|
|
|
Getting Started
|
|
===============
|
|
|
|
libc++ uses LIT to configure and run its tests.
|
|
|
|
The primary way to run the libc++ tests is by using ``make check-cxx``.
|
|
|
|
However since libc++ can be used in any number of possible
|
|
configurations it is important to customize the way LIT builds and runs
|
|
the tests. This guide provides information on how to use LIT directly to
|
|
test libc++.
|
|
|
|
Please see the `Lit Command Guide`_ for more information about LIT.
|
|
|
|
.. _LIT Command Guide: https://llvm.org/docs/CommandGuide/lit.html
|
|
|
|
Usage
|
|
-----
|
|
|
|
After building libc++, you can run parts of the libc++ test suite by simply
|
|
running ``llvm-lit`` on a specified test or directory. If you're unsure
|
|
whether the required libraries have been built, you can use the
|
|
`cxx-test-depends` target. For example:
|
|
|
|
.. code-block:: bash
|
|
|
|
$ cd <monorepo-root>
|
|
$ make -C <build> cxx-test-depends # If you want to make sure the targets get rebuilt
|
|
$ <build>/bin/llvm-lit -sv libcxx/test/std/re # Run all of the std::regex tests
|
|
$ <build>/bin/llvm-lit -sv libcxx/test/std/depr/depr.c.headers/stdlib_h.pass.cpp # Run a single test
|
|
$ <build>/bin/llvm-lit -sv libcxx/test/std/atomics libcxx/test/std/threads # Test std::thread and std::atomic
|
|
|
|
In the default configuration, the tests are built against headers that form a
|
|
fake installation root of libc++. This installation root has to be updated when
|
|
changes are made to the headers, so you should re-run the `cxx-test-depends`
|
|
target before running the tests manually with `lit` when you make any sort of
|
|
change, including to the headers.
|
|
|
|
Sometimes you'll want to change the way LIT is running the tests. Custom options
|
|
can be specified using the `--param=<name>=<val>` flag. The most common option
|
|
you'll want to change is the standard dialect (ie -std=c++XX). By default the
|
|
test suite will select the newest C++ dialect supported by the compiler and use
|
|
that. However if you want to manually specify the option like so:
|
|
|
|
.. code-block:: bash
|
|
|
|
$ <build>/bin/llvm-lit -sv libcxx/test/std/containers # Run the tests with the newest -std
|
|
$ <build>/bin/llvm-lit -sv libcxx/test/std/containers --param=std=c++03 # Run the tests in C++03
|
|
|
|
Occasionally you'll want to add extra compile or link flags when testing.
|
|
You can do this as follows:
|
|
|
|
.. code-block:: bash
|
|
|
|
$ <build>/bin/llvm-lit -sv libcxx/test --param=compile_flags='-Wcustom-warning'
|
|
$ <build>/bin/llvm-lit -sv libcxx/test --param=link_flags='-L/custom/library/path'
|
|
|
|
Some other common examples include:
|
|
|
|
.. code-block:: bash
|
|
|
|
# Specify a custom compiler.
|
|
$ <build>/bin/llvm-lit -sv libcxx/test/std --param=cxx_under_test=/opt/bin/g++
|
|
|
|
# Disable warnings in the test suite
|
|
$ <build>/bin/llvm-lit -sv libcxx/test --param=enable_warnings=False
|
|
|
|
# Use UBSAN when running the tests.
|
|
$ <build>/bin/llvm-lit -sv libcxx/test --param=use_sanitizer=Undefined
|
|
|
|
Using a custom site configuration
|
|
---------------------------------
|
|
|
|
By default, the libc++ test suite will use a site configuration that matches
|
|
the current CMake configuration. It does so by generating a ``lit.site.cfg``
|
|
file in the build directory from one of the configuration file templates in
|
|
``libcxx/test/configs/``, and pointing ``llvm-lit`` (which is a wrapper around
|
|
``llvm/utils/lit/lit.py``) to that file. So when you're running
|
|
``<build>/bin/llvm-lit``, the generated ``lit.site.cfg`` file is always loaded
|
|
instead of ``libcxx/test/lit.cfg.py``. If you want to use a custom site
|
|
configuration, simply point the CMake build to it using
|
|
``-DLIBCXX_TEST_CONFIG=<path-to-site-config>``, and that site configuration
|
|
will be used instead. That file can use CMake variables inside it to make
|
|
configuration easier.
|
|
|
|
.. code-block:: bash
|
|
|
|
$ cmake <options> -DLIBCXX_TEST_CONFIG=<path-to-site-config>
|
|
$ make -C <build> cxx-test-depends
|
|
$ <build>/bin/llvm-lit -sv libcxx/test # will use your custom config file
|
|
|
|
|
|
LIT Options
|
|
===========
|
|
|
|
:program:`lit` [*options*...] [*filenames*...]
|
|
|
|
Command Line Options
|
|
--------------------
|
|
|
|
To use these options you pass them on the LIT command line as ``--param NAME``
|
|
or ``--param NAME=VALUE``. Some options have default values specified during
|
|
CMake's configuration. Passing the option on the command line will override the
|
|
default.
|
|
|
|
.. program:: lit
|
|
|
|
.. option:: cxx_under_test=<path/to/compiler>
|
|
|
|
Specify the compiler used to build the tests.
|
|
|
|
.. option:: stdlib=<stdlib name>
|
|
|
|
**Values**: libc++, libstdc++, msvc
|
|
|
|
Specify the C++ standard library being tested. The default is libc++ if this
|
|
option is not provided. This option is intended to allow running the libc++
|
|
test suite against other standard library implementations.
|
|
|
|
.. option:: std=<standard version>
|
|
|
|
**Values**: c++03, c++11, c++14, c++17, c++20, c++2b
|
|
|
|
Change the standard version used when building the tests.
|
|
|
|
.. option:: cxx_headers=<path/to/headers>
|
|
|
|
Specify the c++ standard library headers that are tested. By default the
|
|
headers in the source tree are used.
|
|
|
|
.. option:: cxx_library_root=<path/to/lib/>
|
|
|
|
Specify the directory of the libc++ library to be tested. By default the
|
|
library folder of the build directory is used.
|
|
|
|
|
|
.. option:: cxx_runtime_root=<path/to/lib/>
|
|
|
|
Specify the directory of the libc++ library to use at runtime. This directory
|
|
is not added to the linkers search path. This can be used to compile tests
|
|
against one version of libc++ and run them using another. The default value
|
|
for this option is `cxx_library_root`.
|
|
|
|
.. option:: use_system_cxx_lib=<bool>
|
|
|
|
**Default**: False
|
|
|
|
Enable or disable testing against the installed version of libc++ library.
|
|
This impacts whether the ``with_system_cxx_lib`` Lit feature is defined or
|
|
not. The ``cxx_library_root`` and ``cxx_runtime_root`` parameters should
|
|
still be used to specify the path of the library to link to and run against,
|
|
respectively.
|
|
|
|
.. option:: debug_level=<level>
|
|
|
|
**Values**: 0, 1
|
|
|
|
Enable the use of debug mode. Level 0 enables assertions and level 1 enables
|
|
assertions and debugging of iterator misuse.
|
|
|
|
.. option:: use_sanitizer=<sanitizer name>
|
|
|
|
**Values**: Memory, MemoryWithOrigins, Address, Undefined
|
|
|
|
Run the tests using the given sanitizer. If LLVM_USE_SANITIZER was given when
|
|
building libc++ then that sanitizer will be used by default.
|
|
|
|
.. option:: llvm_unwinder
|
|
|
|
Enable the use of LLVM unwinder instead of libgcc.
|
|
|
|
.. option:: builtins_library
|
|
|
|
Path to the builtins library to use instead of libgcc.
|
|
|
|
|
|
Writing Tests
|
|
-------------
|
|
|
|
When writing tests for the libc++ test suite, you should follow a few guidelines.
|
|
This will ensure that your tests can run on a wide variety of hardware and under
|
|
a wide variety of configurations. We have several unusual configurations such as
|
|
building the tests on one host but running them on a different host, which add a
|
|
few requirements to the test suite. Here's some stuff you should know:
|
|
|
|
- All tests are run in a temporary directory that is unique to that test and
|
|
cleaned up after the test is done.
|
|
- When a test needs data files as inputs, these data files can be saved in the
|
|
repository (when reasonable) and referenced by the test as
|
|
``// FILE_DEPENDENCIES: <path-to-dependencies>``. Copies of these files or
|
|
directories will be made available to the test in the temporary directory
|
|
where it is run.
|
|
- You should never hardcode a path from the build-host in a test, because that
|
|
path will not necessarily be available on the host where the tests are run.
|
|
- You should try to reduce the runtime dependencies of each test to the minimum.
|
|
For example, requiring Python to run a test is bad, since Python is not
|
|
necessarily available on all devices we may want to run the tests on (even
|
|
though supporting Python is probably trivial for the build-host).
|
|
|
|
Benchmarks
|
|
==========
|
|
|
|
Libc++ contains benchmark tests separately from the test of the test suite.
|
|
The benchmarks are written using the `Google Benchmark`_ library, a copy of which
|
|
is stored in the libc++ repository.
|
|
|
|
For more information about using the Google Benchmark library see the
|
|
`official documentation <https://github.com/google/benchmark>`_.
|
|
|
|
.. _`Google Benchmark`: https://github.com/google/benchmark
|
|
|
|
Building Benchmarks
|
|
-------------------
|
|
|
|
The benchmark tests are not built by default. The benchmarks can be built using
|
|
the ``cxx-benchmarks`` target.
|
|
|
|
An example build would look like:
|
|
|
|
.. code-block:: bash
|
|
|
|
$ cd build
|
|
$ cmake [options] <path to libcxx sources>
|
|
$ make cxx-benchmarks
|
|
|
|
This will build all of the benchmarks under ``<libcxx-src>/benchmarks`` to be
|
|
built against the just-built libc++. The compiled tests are output into
|
|
``build/benchmarks``.
|
|
|
|
The benchmarks can also be built against the platforms native standard library
|
|
using the ``-DLIBCXX_BUILD_BENCHMARKS_NATIVE_STDLIB=ON`` CMake option. This
|
|
is useful for comparing the performance of libc++ to other standard libraries.
|
|
The compiled benchmarks are named ``<test>.libcxx.out`` if they test libc++ and
|
|
``<test>.native.out`` otherwise.
|
|
|
|
Also See:
|
|
|
|
* :ref:`Building Libc++ <build instructions>`
|
|
* :ref:`CMake Options`
|
|
|
|
Running Benchmarks
|
|
------------------
|
|
|
|
The benchmarks must be run manually by the user. Currently there is no way
|
|
to run them as part of the build.
|
|
|
|
For example:
|
|
|
|
.. code-block:: bash
|
|
|
|
$ cd build/benchmarks
|
|
$ make cxx-benchmarks
|
|
$ ./algorithms.libcxx.out # Runs all the benchmarks
|
|
$ ./algorithms.libcxx.out --benchmark_filter=BM_Sort.* # Only runs the sort benchmarks
|
|
|
|
For more information about running benchmarks see `Google Benchmark`_.
|