Rename cxx-benchmark-unittests target and convert to LIT.

This patch renames the cxx-benchmark-unittests to check-cxx-benchmarks
and converts the target to use LIT in order to make the tests run faster
and provide better output.

In particular this runs each benchmark in a suite one by one, allowing
more parallelism while ensuring output isn't garbage with multiple threads.

Additionally, it adds the CMake flag '-DLIBCXX_BENCHMARK_TEST_ARGS=<list>'
to specify what options are passed when running the benchmarks.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@346888 91177308-0d34-0410-b5e6-96231b3b80d8

utils/libcxx/test/googlebenchmark.py

@@ -0,0 +1,122 @@
+from __future__ import absolute_import
+import os
+import subprocess
+import sys
+
+import lit.Test
+import lit.TestRunner
+import lit.util
+from lit.formats.base import TestFormat
+
+kIsWindows = sys.platform in ['win32', 'cygwin']
+
+class GoogleBenchmark(TestFormat):
+    def __init__(self, test_sub_dirs, test_suffix, benchmark_args=[]):
+        self.benchmark_args = list(benchmark_args)
+        self.test_sub_dirs = os.path.normcase(str(test_sub_dirs)).split(';')
+
+        # On Windows, assume tests will also end in '.exe'.
+        exe_suffix = str(test_suffix)
+        if kIsWindows:
+            exe_suffix += '.exe'
+
+        # Also check for .py files for testing purposes.
+        self.test_suffixes = {exe_suffix, test_suffix + '.py'}
+
+    def getBenchmarkTests(self, path, litConfig, localConfig):
+        """getBenchmarkTests(path) - [name]
+
+        Return the tests available in gtest executable.
+
+        Args:
+          path: String path to a gtest executable
+          litConfig: LitConfig instance
+          localConfig: TestingConfig instance"""
+
+        # TODO: allow splitting tests according to the "benchmark family" so
+        # the output for a single family of tests all belongs to the same test
+        # target.
+        list_test_cmd = [path, '--benchmark_list_tests']
+        try:
+            output = subprocess.check_output(list_test_cmd,
+                                             env=localConfig.environment)
+        except subprocess.CalledProcessError as exc:
+            litConfig.warning(
+                "unable to discover google-benchmarks in %r: %s. Process output: %s"
+                % (path, sys.exc_info()[1], exc.output))
+            raise StopIteration
+
+        nested_tests = []
+        for ln in output.splitlines(False):  # Don't keep newlines.
+            ln = lit.util.to_string(ln)
+            if not ln.strip():
+                continue
+
+            index = 0
+            while ln[index*2:index*2+2] == '  ':
+                index += 1
+            while len(nested_tests) > index:
+                nested_tests.pop()
+
+            ln = ln[index*2:]
+            if ln.endswith('.'):
+                nested_tests.append(ln)
+            elif any([name.startswith('DISABLED_')
+                      for name in nested_tests + [ln]]):
+                # Gtest will internally skip these tests. No need to launch a
+                # child process for it.
+                continue
+            else:
+                yield ''.join(nested_tests) + ln
+
+    def getTestsInDirectory(self, testSuite, path_in_suite,
+                            litConfig, localConfig):
+        source_path = testSuite.getSourcePath(path_in_suite)
+        for subdir in self.test_sub_dirs:
+            dir_path = os.path.join(source_path, subdir)
+            if not os.path.isdir(dir_path):
+                continue
+            for fn in lit.util.listdir_files(dir_path,
+                                             suffixes=self.test_suffixes):
+                # Discover the tests in this executable.
+                execpath = os.path.join(source_path, subdir, fn)
+                testnames = self.getBenchmarkTests(execpath, litConfig, localConfig)
+                for testname in testnames:
+                    testPath = path_in_suite + (subdir, fn, testname)
+                    yield lit.Test.Test(testSuite, testPath, localConfig,
+                                        file_path=execpath)
+
+    def execute(self, test, litConfig):
+        testPath,testName = os.path.split(test.getSourcePath())
+        while not os.path.exists(testPath):
+            # Handle GTest parametrized and typed tests, whose name includes
+            # some '/'s.
+            testPath, namePrefix = os.path.split(testPath)
+            testName = namePrefix + '/' + testName
+
+        cmd = [testPath, '--benchmark_filter=%s$' % testName ] + self.benchmark_args
+
+        if litConfig.noExecute:
+            return lit.Test.PASS, ''
+
+        try:
+            out, err, exitCode = lit.util.executeCommand(
+                cmd, env=test.config.environment,
+                timeout=litConfig.maxIndividualTestTime)
+        except lit.util.ExecuteCommandTimeoutException:
+            return (lit.Test.TIMEOUT,
+                    'Reached timeout of {} seconds'.format(
+                        litConfig.maxIndividualTestTime)
+                   )
+
+        if exitCode:
+            return lit.Test.FAIL, out + err
+
+        passing_test_line = testName
+        if passing_test_line not in out:
+            msg = ('Unable to find %r in google benchmark output:\n\n%s%s' %
+                   (passing_test_line, out, err))
+            return lit.Test.UNRESOLVED, msg
+
+        return lit.Test.PASS, err + out
+