[libcxxabi] Refactor test timing logic and disable by default.

Summary:
When using LIT the timing output is entirely unused but introduces a dependency on `<chrono>`. When libc++ is built without a montonic clock this causes some of the tests to fail.
This patch factors out all of the timing logic into `support/timer.hpp` and disables it by default. To enable the timing you must define `LIBCXXABI_TIME_TESTS`.



Reviewers: mclow.lists, danalbert, jroelofs

Reviewed By: jroelofs

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D6391

git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@222701 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 46 insertions, 0 deletions

diff --git a/test/support/timer.hpp b/test/support/timer.hpp
new file mode 100644
index 0000000..a3d51d7
--- /dev/null
+++ b/test/support/timer.hpp
@@ -0,0 +1,46 @@
+#ifndef TIMER_HPP
+#define TIMER_HPP
+
+// Define LIBCXXABI_NO_TIMER to disable testing with a timer.
+#ifndef LIBCXXABI_NO_TIMER
+
+#include <chrono>
+#include <iostream>
+
+class timer
+{
+    typedef std::chrono::high_resolution_clock Clock;
+    typedef Clock::time_point TimePoint;
+    typedef std::chrono::microseconds MicroSeconds;
+public:
+    timer() : m_start(Clock::now()) {}
+
+    timer(timer const &) = delete;
+    timer & operator=(timer const &) = delete;
+
+    ~timer()
+    {
+        using std::chrono::duration_cast;
+        TimePoint end = Clock::now();
+        MicroSeconds us = duration_cast<MicroSeconds>(end - m_start);
+        std::cout << us.count() << " microseconds\n";
+    }
+
+private:
+    TimePoint m_start;
+};
+
+#else /* LIBCXXABI_NO_TIMER */
+
+class timer
+{
+public:
+    timer() {}
+    timer(timer const &) = delete;
+    timer & operator=(timer const &) = delete;
+    ~timer() {}
+};
+
+#endif /* LIBCXXABI_TIME_TESTS */
+
+#endif /* TIMER_HPP */
\ No newline at end of file