[libcxx-commits] [libcxx] [libc++] Fix `std::atomic::wait` ulock wait UL_COMPARE_AND_WAIT64 (PR #92783)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: Hui (huixie90)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/92783.diff


2 Files Affected:

- (modified) libcxx/src/atomic.cpp (+3-3) 
- (added) libcxx/test/libcxx/atomics/atomics.syn/wait.pass.cpp (+30) 


``````````diff
diff --git a/libcxx/src/atomic.cpp b/libcxx/src/atomic.cpp
index 44100d4414e0d..031f247f88c2f 100644
--- a/libcxx/src/atomic.cpp
+++ b/libcxx/src/atomic.cpp
@@ -69,17 +69,17 @@ extern "C" int __ulock_wait(
     uint32_t operation, void* addr, uint64_t value, uint32_t timeout); /* timeout is specified in microseconds */
 extern "C" int __ulock_wake(uint32_t operation, void* addr, uint64_t wake_value);
 
-#  define UL_COMPARE_AND_WAIT 1
+#  define UL_COMPARE_AND_WAIT64 5
 #  define ULF_WAKE_ALL 0x00000100
 
 static void
 __libcpp_platform_wait_on_address(__cxx_atomic_contention_t const volatile* __ptr, __cxx_contention_t __val) {
-  __ulock_wait(UL_COMPARE_AND_WAIT, const_cast<__cxx_atomic_contention_t*>(__ptr), __val, 0);
+  __ulock_wait(UL_COMPARE_AND_WAIT64, const_cast<__cxx_atomic_contention_t*>(__ptr), __val, 0);
 }
 
 static void __libcpp_platform_wake_by_address(__cxx_atomic_contention_t const volatile* __ptr, bool __notify_one) {
   __ulock_wake(
-      UL_COMPARE_AND_WAIT | (__notify_one ? 0 : ULF_WAKE_ALL), const_cast<__cxx_atomic_contention_t*>(__ptr), 0);
+      UL_COMPARE_AND_WAIT64 | (__notify_one ? 0 : ULF_WAKE_ALL), const_cast<__cxx_atomic_contention_t*>(__ptr), 0);
 }
 
 #elif defined(__FreeBSD__) && __SIZEOF_LONG__ == 8
diff --git a/libcxx/test/libcxx/atomics/atomics.syn/wait.pass.cpp b/libcxx/test/libcxx/atomics/atomics.syn/wait.pass.cpp
new file mode 100644
index 0000000000000..f59db4109bfd5
--- /dev/null
+++ b/libcxx/test/libcxx/atomics/atomics.syn/wait.pass.cpp
@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// XFAIL: availability-synchronization_library-missing
+// XFAIL: !has-64-bit-atomics
+
+#include <atomic>
+#include <cassert>
+
+#include "test_macros.h"
+
+void test_85107() {
+  // https://github.com/llvm/llvm-project/issues/85107
+  // [libc++] atomic_wait uses UL_COMPARE_AND_WAIT when it should use UL_COMPARE_AND_WAIT64 on Darwin
+  constexpr std::__cxx_contention_t old_val = 0;
+  constexpr std::__cxx_contention_t new_val = old_val + (1l << 32);
+  std::__cxx_atomic_contention_t ct(new_val);
+  std::__libcpp_atomic_wait(&ct, old_val);
+}
+
+int main(int, char**) {
+  test_85107();
+
+  return 0;
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/92783