[compiler-rt] [TSan] Add interceptor for os_unfair_lock_lock_with_flags (PR #153815)

[Dan Blackwell via llvm-commits]

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@@ -23,6 +36,28 @@ int main() {
   pthread_join(t1, NULL);
   pthread_join(t2, NULL);
   fprintf(stderr, "global_variable = %ld\n", global_variable);
+
+  // CHECK: global_variable = 2
+
+  void *(*func)(void *) = Thread;
+  char flags_available = 0;
+#if defined(__MAC_15_0)
+#  pragma clang diagnostic push
+#  pragma clang diagnostic ignored "-Wunguarded-availability-new"
+  if (&os_unfair_lock_lock_with_flags) {
+#  pragma clang diagnostic pop
+    func = ThreadWithFlags;
+    flags_available = 1;
+  }
+#endif
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DanBlackwell wrote:

> The reason for the complication here is so we pass the 2nd CHECK: global_variable = 4, right?

Yeah, but we can just do all the logic within ThreadWithFlags

https://github.com/llvm/llvm-project/pull/153815