Reduce the number of strcmp calling while initialization

When we do parallel test execution with a process for a test, initialization of gtest become performance bottleneck when the test binary contains many testcases. Especially, some parameterlized test in chromium browser affected by largely when address sanitizer is enabled. Address sanitizer does not allow using optimized strcmp function and test addition in parameterized test require lookup of test case using strcmp. This patch reduces the number of strcmp, it is called when registering parameterized test. Using reverse iterator improves the time to find registered tests in such case. Some tests for chromium browser using address sanitizer finished 2x faster with this patch.

Reduce the number of strcmp calling while initialization
f4d0631a · Takuto Ikuta · 1bccd6f3 · f4d0631a
Commit f4d0631a authored Jun 12, 2018 by Takuto Ikuta
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gtest.cc googletest/src/gtest.cc +3 -3

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--- a/googletest/src/gtest.cc
+++ b/googletest/src/gtest.cc
@@ -4907,11 +4907,11 @@ TestCase* UnitTestImpl::GetTestCase(const char* test_case_name,
                                    Test::SetUpTestCaseFunc set_up_tc,
                                    Test::TearDownTestCaseFunc tear_down_tc) {
  // Can we find a TestCase with the given name?
-  const std::vector<TestCase*>::const_iterator test_case =
-      std::find_if(test_cases_.begin(), test_cases_.end(),
+  const std::vector<TestCase*>::const_reverse_iterator test_case =
+      std::find_if(test_cases_.rbegin(), test_cases_.rend(),
                   TestCaseNameIs(test_case_name));

-  if (test_case != test_cases_.end())
+  if (test_case != test_cases_.rend())
    return *test_case;

  // No.  Let's create one.