[libcxx] Enable building and testing of libcxx with ThreadSanitizer on OS X

[kubamracek]

Summary

This patch enables building and testing libcxx under ThreadSanitizer on OS X. CMake builds that have -DLLVM_USE_SANITIZER=Thread will automatically build libcxx with -fsanitize=thread and testing via lit then runs under TSan. There was one more typo in a python config script, but after that is fixed I verified that the TSan build works.

This diff also adds a regression test for the bug (data race) fixed in https://reviews.llvm.org/D24028. If you revert the fix, TSan will report a data race in call_once. If approved, I’ll commit the test separately.

[kubamracek]

ping

lib/CMakeLists.txt

 add_library_flags("${LIBCXX_CXX_ABI_LIBRARY}")
 add_library_flags_if(LIBCXX_ENABLE_STATIC_ABI_LIBRARY "-Wl,-Bdynamic" "-Wl,--no-whole-archive")
 
 if (APPLE AND LLVM_USE_SANITIZER)
   if ("${LLVM_USE_SANITIZER}" STREQUAL "Address")
     set(LIBFILE "libclang_rt.asan_osx_dynamic.dylib")
   elseif("${LLVM_USE_SANITIZER}" STREQUAL "Undefined")
     set(LIBFILE "libclang_rt.ubsan_osx_dynamic.dylib")
+  elseif("${LLVM_USE_SANITIZER}" STREQUAL "Thread")
+    set(LIBFILE "libclang_rt.tsan_osx_dynamic.dylib")
   else()
     message(WARNING "LLVM_USE_SANITIZER=${LLVM_USE_SANITIZER} is not supported on OS X")
   endif()
   if (LIBFILE)
     execute_process(COMMAND ${CMAKE_CXX_COMPILER} -print-file-name=lib OUTPUT_VARIABLE LIBDIR RESULT_VARIABLE Result)
     if (NOT ${Result} EQUAL "0")
       message(FATAL "Failed to find library resource directory")
     endif()

test/libcxx/test/target_info.py

def allow_cxxabi_link(self):
         # See PR22654.
         if(self.full_config.get_lit_conf('name', '') == 'libc++abi'):
             return True
         # Don't link libc++abi explicitly on OS X because the symbols
         # should be available in libc++ directly.
         return False
 
     def add_sanitizer_features(self, sanitizer_type, features):
-        if san == 'Undefined':
+        if sanitizer_type == 'Undefined':
             features.add('sanitizer-new-delete')
 
 
 class FreeBSDLocalTI(DefaultTargetInfo):
     def __init__(self, full_config):
         super(FreeBSDLocalTI, self).__init__(full_config)
 
     def add_locale_features(self, features):

test/std/thread/thread.mutex/thread.once/thread.once.callonce/race.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// UNSUPPORTED: libcpp-has-no-threads
+
+// <mutex>
+
+// struct once_flag;
+
+// template<class Callable, class ...Args>
+//   void call_once(once_flag& flag, Callable&& func, Args&&... args);
+
+// This test is supposed to be run with ThreadSanitizer and verifies that
+// call_once propertly synchronizes user state, a data race that was fixed
+// in https://reviews.llvm.org/D24028.
+
+#include <mutex>
+#include <thread>
+#include <cassert>
+
+std::once_flag flg0;
+long global = 0;
+
+void init0()
+{
+    ++global;
+}
+
+void f0()
+{
+    std::call_once(flg0, init0);
+    assert(global == 1);
+}
+
+int main()
+{
+    std::thread t0(f0);
+    std::thread t1(f0);
+    t0.join();
+    t1.join();
+    assert(global == 1);
+}