[compiler-rt] [tsan] Add symbol for `__atomic_is_lock_free` (PR #218809)

[via llvm-commits]

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@@ -0,0 +1,85 @@
+// RUN: %clangxx_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
+#include <atomic>
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
+
+struct alignas(16) Large {
+  char data[16];
+};
+
+struct Huge {
+  char data[32];
+};
+
+extern "C" bool __atomic_is_lock_free(size_t size, const volatile void *ptr);
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zhangweize9-cyber wrote:

Why using `extern "C"`? `__atomic_is_lock_free` is a [built-in](https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html#index-_005f_005fatomic_005fis_005flock_005ffree) function for gcc.

https://github.com/llvm/llvm-project/pull/218809