1============== 2Testing libc++ 3============== 4 5.. contents:: 6 :local: 7 8Getting Started 9=============== 10 11libc++ uses LIT to configure and run its tests. 12 13The primary way to run the libc++ tests is by using `make check-libcxx`. 14 15However since libc++ can be used in any number of possible 16configurations it is important to customize the way LIT builds and runs 17the tests. This guide provides information on how to use LIT directly to 18test libc++. 19 20Please see the `Lit Command Guide`_ for more information about LIT. 21 22.. _LIT Command Guide: http://llvm.org/docs/CommandGuide/lit.html 23 24Setting up the Environment 25-------------------------- 26 27After building libc++ you must setup your environment to test libc++ using 28LIT. 29 30#. Create a shortcut to the actual lit executable so that you can invoke it 31 easily from the command line. 32 33 .. code-block:: bash 34 35 $ alias lit='python path/to/llvm/utils/lit/lit.py' 36 37#. Tell LIT where to find your build configuration. 38 39 .. code-block:: bash 40 41 $ export LIBCXX_SITE_CONFIG=path/to/build-libcxx/test/lit.site.cfg 42 43Example Usage 44------------- 45 46Once you have your environment set up and you have built libc++ you can run 47parts of the libc++ test suite by simply running `lit` on a specified test or 48directory. For example: 49 50.. code-block:: bash 51 52 $ cd path/to/src/libcxx 53 $ lit -sv test/std/re # Run all of the std::regex tests 54 $ lit -sv test/std/depr/depr.c.headers/stdlib_h.pass.cpp # Run a single test 55 $ lit -sv test/std/atomics test/std/threads # Test std::thread and std::atomic 56 57Sometimes you'll want to change the way LIT is running the tests. Custom options 58can be specified using the `--param=<name>=<val>` flag. The most common option 59you'll want to change is the standard dialect (ie -std=c++XX). By default the 60test suite will select the newest C++ dialect supported by the compiler and use 61that. However if you want to manually specify the option like so: 62 63.. code-block:: bash 64 65 $ lit -sv test/std/containers # Run the tests with the newest -std 66 $ lit -sv --param=std=c++03 test/std/containers # Run the tests in C++03 67 68Occasionally you'll want to add extra compile or link flags when testing. 69You can do this as follows: 70 71.. code-block:: bash 72 73 $ lit -sv --param=compile_flags='-Wcustom-warning' 74 $ lit -sv --param=link_flags='-L/custom/library/path' 75 76Some other common examples include: 77 78.. code-block:: bash 79 80 # Specify a custom compiler. 81 $ lit -sv --param=cxx_under_test=/opt/bin/g++ test/std 82 83 # Enable warnings in the test suite 84 $ lit -sv --param=enable_warnings=true test/std 85 86 # Use UBSAN when running the tests. 87 $ lit -sv --param=use_sanitizer=Undefined 88 89 90LIT Options 91=========== 92 93:program:`lit` [*options*...] [*filenames*...] 94 95Command Line Options 96-------------------- 97 98To use these options you pass them on the LIT command line as --param NAME or 99--param NAME=VALUE. Some options have default values specified during CMake's 100configuration. Passing the option on the command line will override the default. 101 102.. program:: lit 103 104.. option:: cxx_under_test=<path/to/compiler> 105 106 Specify the compiler used to build the tests. 107 108.. option:: cxx_stdlib_under_test=<stdlib name> 109 110 **Values**: libc++, libstdc++ 111 112 Specify the C++ standard library being tested. Unless otherwise specified 113 libc++ is used. This option is intended to allow running the libc++ test 114 suite against other standard library implementations. 115 116.. option:: std=<standard version> 117 118 **Values**: c++98, c++03, c++11, c++14, c++17, c++2a 119 120 Change the standard version used when building the tests. 121 122.. option:: libcxx_site_config=<path/to/lit.site.cfg> 123 124 Specify the site configuration to use when running the tests. This option 125 overrides the environment variable LIBCXX_SITE_CONFIG. 126 127.. option:: cxx_headers=<path/to/headers> 128 129 Specify the c++ standard library headers that are tested. By default the 130 headers in the source tree are used. 131 132.. option:: cxx_library_root=<path/to/lib/> 133 134 Specify the directory of the libc++ library to be tested. By default the 135 library folder of the build directory is used. This option cannot be used 136 when use_system_cxx_lib is provided. 137 138 139.. option:: cxx_runtime_root=<path/to/lib/> 140 141 Specify the directory of the libc++ library to use at runtime. This directory 142 is not added to the linkers search path. This can be used to compile tests 143 against one version of libc++ and run them using another. The default value 144 for this option is `cxx_library_root`. 145 146.. option:: use_system_cxx_lib=<bool> 147 148 **Default**: False 149 150 Enable or disable testing against the installed version of libc++ library. 151 Note: This does not use the installed headers. 152 153.. option:: use_lit_shell=<bool> 154 155 Enable or disable the use of LIT's internal shell in ShTests. If the 156 environment variable LIT_USE_INTERNAL_SHELL is present then that is used as 157 the default value. Otherwise the default value is True on Windows and False 158 on every other platform. 159 160.. option:: compile_flags="<list-of-args>" 161 162 Specify additional compile flags as a space delimited string. 163 Note: This options should not be used to change the standard version used. 164 165.. option:: link_flags="<list-of-args>" 166 167 Specify additional link flags as a space delimited string. 168 169.. option:: debug_level=<level> 170 171 **Values**: 0, 1 172 173 Enable the use of debug mode. Level 0 enables assertions and level 1 enables 174 assertions and debugging of iterator misuse. 175 176.. option:: use_sanitizer=<sanitizer name> 177 178 **Values**: Memory, MemoryWithOrigins, Address, Undefined 179 180 Run the tests using the given sanitizer. If LLVM_USE_SANITIZER was given when 181 building libc++ then that sanitizer will be used by default. 182 183.. option:: color_diagnostics 184 185 Enable the use of colorized compile diagnostics. If the color_diagnostics 186 option is specified or the environment variable LIBCXX_COLOR_DIAGNOSTICS is 187 present then color diagnostics will be enabled. 188 189.. option:: llvm_unwinder 190 191 Enable the use of LLVM unwinder instead of libgcc. 192 193.. option:: builtins_library 194 195 Path to the builtins library to use instead of libgcc. 196 197 198Environment Variables 199--------------------- 200 201.. envvar:: LIBCXX_SITE_CONFIG=<path/to/lit.site.cfg> 202 203 Specify the site configuration to use when running the tests. 204 Also see `libcxx_site_config`. 205 206.. envvar:: LIBCXX_COLOR_DIAGNOSTICS 207 208 If ``LIBCXX_COLOR_DIAGNOSTICS`` is defined then the test suite will attempt 209 to use color diagnostic outputs from the compiler. 210 Also see `color_diagnostics`. 211 212Benchmarks 213========== 214 215Libc++ contains benchmark tests separately from the test of the test suite. 216The benchmarks are written using the `Google Benchmark`_ library, a copy of which 217is stored in the libc++ repository. 218 219For more information about using the Google Benchmark library see the 220`official documentation <https://github.com/google/benchmark>`_. 221 222.. _`Google Benchmark`: https://github.com/google/benchmark 223 224Building Benchmarks 225------------------- 226 227The benchmark tests are not built by default. The benchmarks can be built using 228the ``cxx-benchmarks`` target. 229 230An example build would look like: 231 232.. code-block:: bash 233 234 $ cd build 235 $ cmake [options] <path to libcxx sources> 236 $ make cxx-benchmarks 237 238This will build all of the benchmarks under ``<libcxx-src>/benchmarks`` to be 239built against the just-built libc++. The compiled tests are output into 240``build/benchmarks``. 241 242The benchmarks can also be built against the platforms native standard library 243using the ``-DLIBCXX_BUILD_BENCHMARKS_NATIVE_STDLIB=ON`` CMake option. This 244is useful for comparing the performance of libc++ to other standard libraries. 245The compiled benchmarks are named ``<test>.libcxx.out`` if they test libc++ and 246``<test>.native.out`` otherwise. 247 248Also See: 249 250 * :ref:`Building Libc++ <build instructions>` 251 * :ref:`CMake Options` 252 253Running Benchmarks 254------------------ 255 256The benchmarks must be run manually by the user. Currently there is no way 257to run them as part of the build. 258 259For example: 260 261.. code-block:: bash 262 263 $ cd build/benchmarks 264 $ make cxx-benchmarks 265 $ ./algorithms.libcxx.out # Runs all the benchmarks 266 $ ./algorithms.libcxx.out --benchmark_filter=BM_Sort.* # Only runs the sort benchmarks 267 268For more information about running benchmarks see `Google Benchmark`_. 269