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

[via libcxx-commits]

https://github.com/huixie90 updated https://github.com/llvm/llvm-project/pull/92783

>From c92abdccff4d81380e16e069b6d1b70e4b9ef0af Mon Sep 17 00:00:00 2001
From: Hui <hui.xie0621 at gmail.com>
Date: Mon, 20 May 2024 17:44:11 +0100
Subject: [PATCH 1/2] [libc++] Fix `std::atomic::wait` ulock wait
 UL_COMPARE_AND_WAIT64

---
 libcxx/src/atomic.cpp                         |  6 ++--
 .../libcxx/atomics/atomics.syn/wait.pass.cpp  | 30 +++++++++++++++++++
 2 files changed, 33 insertions(+), 3 deletions(-)
 create mode 100644 libcxx/test/libcxx/atomics/atomics.syn/wait.pass.cpp

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;
+}

>From 21d3d4ccfe70cabacc6f657bb56e08ea7f6cc5a6 Mon Sep 17 00:00:00 2001
From: Hui <hui.xie0621 at gmail.com>
Date: Mon, 20 May 2024 18:10:48 +0100
Subject: [PATCH 2/2] linux fix

---
 .../test/libcxx/atomics/atomics.syn/wait.pass.cpp  | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/libcxx/test/libcxx/atomics/atomics.syn/wait.pass.cpp b/libcxx/test/libcxx/atomics/atomics.syn/wait.pass.cpp
index f59db4109bfd5..9a1aa906fd83b 100644
--- a/libcxx/test/libcxx/atomics/atomics.syn/wait.pass.cpp
+++ b/libcxx/test/libcxx/atomics/atomics.syn/wait.pass.cpp
@@ -15,12 +15,14 @@
 #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);
+  if constexpr (sizeof(std::__cxx_contention_t) == 8) {
+    // 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**) {