Revert r103213. It broke several sections of live website.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103219 91177308-0d34-0410-b5e6-96231b3b80d8

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+=pod
+
+=head1 NAME
+
+lit - LLVM Integrated Tester
+
+=head1 SYNOPSIS
+
+B<lit> [I<options>] [I<tests>]
+
+=head1 DESCRIPTION
+
+B<lit> is a portable tool for executing LLVM and Clang style test suites,
+summarizing their results, and providing indication of failures. B<lit> is
+designed to be a lightweight testing tool with as simple a user interface as
+possible.
+
+B<lit> should be run with one or more I<tests> to run specified on the command
+line. Tests can be either individual test files or directories to search for
+tests (see L<"TEST DISCOVERY">).
+
+Each specified test will be executed (potentially in parallel) and once all
+tests have been run B<lit> will print summary information on the number of tests
+which passed or failed (see L<"TEST STATUS RESULTS">). The B<lit> program will
+execute with a non-zero exit code if any tests fail.
+
+By default B<lit> will use a succinct progress display and will only print
+summary information for test failures. See L<"OUTPUT OPTIONS"> for options
+controlling the B<lit> progress display and output.
+
+B<lit> also includes a number of options for controlling how tests are exected
+(specific features may depend on the particular test format). See L<"EXECUTION
+OPTIONS"> for more information.
+
+Finally, B<lit> also supports additional options for only running a subset of
+the options specified on the command line, see L<"SELECTION OPTIONS"> for
+more information.
+
+Users interested in the B<lit> architecture or designing a B<lit> testing
+implementation should see L<"LIT ARCHITECTURE">
+
+=head1 GENERAL OPTIONS
+
+=over
+
+=item B<-h>, B<--help>
+
+Show the B<lit> help message.
+
+=item B<-j> I<N>, B<--threads>=I<N>
+
+Run I<N> tests in parallel. By default, this is automatically chosen to match
+the number of detected available CPUs.
+
+=item B<--config-prefix>=I<NAME>
+
+Search for I<NAME.cfg> and I<NAME.site.cfg> when searching for test suites,
+instead of I<lit.cfg> and I<lit.site.cfg>.
+
+=item B<--param> I<NAME>, B<--param> I<NAME>=I<VALUE>
+
+Add a user defined parameter I<NAME> with the given I<VALUE> (or the empty
+string if not given). The meaning and use of these parameters is test suite
+dependent.
+
+=back 
+
+=head1 OUTPUT OPTIONS
+
+=over
+
+=item B<-q>, B<--quiet>
+
+Suppress any output except for test failures.
+
+=item B<-s>, B<--succinct>
+
+Show less output, for example don't show information on tests that pass.
+
+=item B<-v>, B<--verbose>
+
+Show more information on test failures, for example the entire test output
+instead of just the test result.
+
+=item B<--no-progress-bar>
+
+Do not use curses based progress bar.
+
+=back 
+
+=head1 EXECUTION OPTIONS
+
+=over
+
+=item B<--path>=I<PATH>
+
+Specify an addition I<PATH> to use when searching for executables in tests.
+
+=item B<--vg>
+
+Run individual tests under valgrind (using the memcheck tool). The
+I<--error-exitcode> argument for valgrind is used so that valgrind failures will
+cause the program to exit with a non-zero status.
+
+=item B<--vg-arg>=I<ARG>
+
+When I<--vg> is used, specify an additional argument to pass to valgrind itself.
+
+=item B<--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. Note that this option is most useful with I<-j
+1>.
+
+=back
+
+=head1 SELECTION OPTIONS
+
+=over
+
+=item B<--max-tests>=I<N>
+
+Run at most I<N> tests and then terminate.
+
+=item B<--max-time>=I<N>
+
+Spend at most I<N> seconds (approximately) running tests and then terminate.
+
+=item B<--shuffle>
+
+Run the tests in a random order.
+
+=back
+
+=head1 ADDITIONAL OPTIONS
+
+=over
+
+=item B<--debug>
+
+Run B<lit> in debug mode, for debugging configuration issues and B<lit> itself.
+
+=item B<--show-suites>
+
+List the discovered test suites as part of the standard output.
+
+=item B<--no-tcl-as-sh>
+
+Run Tcl scripts internally (instead of converting to shell scripts).
+
+=item B<--repeat>=I<N>
+
+Run each test I<N> times. Currently this is primarily useful for timing tests,
+other results are not collated in any reasonable fashion.
+
+=back
+
+=head1 EXIT STATUS
+
+B<lit> will exit with an exit code of 1 if there are any FAIL or XPASS
+results. Otherwise, it will exit with the status 0. Other exit codes used for
+non-test related failures (for example a user error or an internal program
+error).
+
+=head1 TEST DISCOVERY
+
+The inputs passed to B<lit> can be either individual tests, or entire
+directories or hierarchies of tests to run. When B<lit> starts up, the first
+thing it does is convert the inputs into a complete list of tests to run as part
+of I<test discovery>.
+
+In the B<lit> model, every test must exist inside some I<test suite>. B<lit>
+resolves the inputs specified on the command line to test suites by searching
+upwards from the input path until it finds a I<lit.cfg> or I<lit.site.cfg>
+file. These files serve as both a marker of test suites and as configuration
+files which B<lit> loads in order to understand how to find and run the tests
+inside the test suite.
+
+Once B<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, B<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 B<lit> to provide convenient and flexible
+support for out-of-tree builds.
+
+=head1 TEST STATUS RESULTS
+
+Each test ultimately produces one of the following six results:
+
+=over
+
+=item B<PASS>
+
+The test succeeded.
+
+=item B<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.
+
+=item B<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 feautre they test was broken and has been fixed).
+
+=item B<FAIL>
+
+The test failed.
+
+=item B<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.
+
+=item B<UNSUPPORTED>
+
+The test is not supported in this environment. This is used by test formats
+which can report unsupported tests.
+
+=back
+
+Depending on the test format tests may produce additional information about
+their status (generally only for failures). See the L<Output|"LIT OUTPUT">
+section for more information.
+
+=head1 LIT INFRASTRUCTURE
+
+This section describes the B<lit> testing architecture for users interested in
+creating a new B<lit> testing implementation, or extending an existing one.
+
+B<lit> proper is primarily an infrastructure for discovering and running
+arbitrary tests, and to expose a single convenient interface to these
+tests. B<lit> itself doesn't know how to run tests, rather this logic is
+defined by I<test suites>.
+
+=head2 TEST SUITES
+
+As described in L<"TEST DISCOVERY">, tests are always located inside a I<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.
+
+B<lit> identifies test suites as directories containing I<lit.cfg> or
+I<lit.site.cfg> files (see also B<--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 B<--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 just Python modules which will be executed. When the config file
+is executed, two important global variables are predefined:
+
+=over
+
+=item B<lit>
+
+The global B<lit> configuration object (a I<LitConfig> instance), which defines
+the builtin test formats, global configuration parameters, and other helper
+routines for implementing test configurations.
+
+=item B<config>
+
+This is the config object (a I<TestingConfig> instance) for the test suite,
+which the config file is expected to populate. The following variables are also
+available on the I<config> object, some of which must be set by the config and
+others are optional or predefined:
+
+B<name> I<[required]> The name of the test suite, for use in reports and
+diagnostics.
+
+B<test_format> I<[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 I<lit.formats> module.
+
+B<test_src_root> The filesystem path to the test suite root. For out-of-dir
+builds this is the directory that will be scanned for tests.
+
+B<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
+places.
+
+B<environment> A dictionary representing the environment to use when executing
+tests in the suite.
+
+B<suffixes> For B<lit> test formats which scan directories for tests, this
+variable as a list of suffixes to identify test files. Used by: I<ShTest>,
+I<TclTest>.
+
+B<substitutions> For B<lit> test formats which substitute variables into a test
+script, the list of substitutions to perform. Used by: I<ShTest>, I<TclTest>.
+
+B<unsupported> Mark an unsupported directory, all tests within it will be
+reported as unsupported. Used by: I<ShTest>, I<TclTest>.
+
+B<parent> The parent configuration, this is the config object for the directory
+containing the test suite, or None.
+
+B<on_clone> The config is actually cloned for every subdirectory inside a test
+suite, to allow local configuration on a per-directory basis. The I<on_clone>
+variable can be set to a Python function which will be called whenever a
+configuration is cloned (for a subdirectory). The function should takes three
+arguments: (1) the parent configuration, (2) the new configuration (which the
+I<on_clone> function will generally modify), and (3) the test path to the new
+directory being scanned.
+
+=back
+
+=head2 TEST DISCOVERY
+
+Once test suites are located, B<lit> recursively traverses the source directory
+(following I<test_src_root>) looking for tests. When B<lit> enters a
+sub-directory, it first checks to see if a nest 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 L<"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 I<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.
+
+=head2 LOCAL CONFIGURATION FILES
+
+When B<lit> loads a subdirectory in a test suite, it instantiates a local test
+configuration by cloning the configuration for the parent direction -- the root
+of this configuration chain will always be a test suite. Once the test
+configuration is cloned B<lit> checks for a I<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.
+
+=head2 LIT EXAMPLE TESTS
+
+The B<lit> distribution contains several example implementations of test suites
+in the I<ExampleTests> directory.
+
+=head1 SEE ALSO
+
+L<valgrind(1)>
+
+=head1 AUTHOR
+
+Written by Daniel Dunbar and maintained by the LLVM Team (L<http://llvm.org>).
+
+=cut