[libcxx-commits] [libcxx] [libc++] Allows any types of size 4 and 8 to use native platform ulock_wait (PR #161086)

[Louis Dionne via libcxx-commits]

================
@@ -70,42 +77,97 @@ __libcpp_atomic_monitor(__cxx_atomic_contention_t const volatile*) _NOEXCEPT;
 _LIBCPP_EXPORTED_FROM_ABI void
 __libcpp_atomic_wait(__cxx_atomic_contention_t const volatile*, __cxx_contention_t) _NOEXCEPT;
 
+// new dylib interface
+_LIBCPP_AVAILABILITY_NEW_SYNC _LIBCPP_EXPORTED_FROM_ABI __cxx_contention_t
+__libcpp_atomic_monitor_global(void const volatile* __address) _NOEXCEPT;
+
+_LIBCPP_AVAILABILITY_NEW_SYNC _LIBCPP_EXPORTED_FROM_ABI void
+__libcpp_atomic_wait_global_table(void const volatile* __address, __cxx_contention_t __monitor_value) _NOEXCEPT;
+
+_LIBCPP_AVAILABILITY_NEW_SYNC _LIBCPP_EXPORTED_FROM_ABI void
+__libcpp_atomic_notify_one_global_table(void const volatile*) _NOEXCEPT;
+_LIBCPP_AVAILABILITY_NEW_SYNC _LIBCPP_EXPORTED_FROM_ABI void
+__libcpp_atomic_notify_all_global_table(void const volatile*) _NOEXCEPT;
+
+template <std::size_t _Size>
+_LIBCPP_AVAILABILITY_NEW_SYNC _LIBCPP_EXPORTED_FROM_ABI void
+
+__libcpp_atomic_wait_native(void const volatile* __address, void const* __old_value) _NOEXCEPT;
+template <std::size_t _Size>
+_LIBCPP_AVAILABILITY_NEW_SYNC _LIBCPP_EXPORTED_FROM_ABI void
+__libcpp_atomic_notify_one_native(const volatile void*) _NOEXCEPT;
+
+template <std::size_t _Size>
+_LIBCPP_AVAILABILITY_NEW_SYNC _LIBCPP_EXPORTED_FROM_ABI void
+__libcpp_atomic_notify_all_native(const volatile void*) _NOEXCEPT;
+
----------------
ldionne wrote:

First, I suggest simplifying this code a bit by always defining the list of sizes that support a native wait on the platform. So, at the top level, you can simply have

```c++
#ifdef __linux__
#  define _LIBCPP_NATIVE_PLATFORM_WAIT_SIZES(_APPLY) _APPLY(4)
#elif defined(__APPLE__)
#  define _LIBCPP_NATIVE_PLATFORM_WAIT_SIZES(_APPLY) _APPLY(4) _APPLY(8)
#elif defined(__FreeBSD__) && __SIZEOF_LONG__ == 8
#  define _LIBCPP_NATIVE_PLATFORM_WAIT_SIZES(_APPLY) _APPLY(8)
#else
#  define _LIBCPP_NATIVE_PLATFORM_WAIT_SIZES(_APPLY) _APPLY(sizeof(__cxx_contention_t))
#endif
```

https://github.com/llvm/llvm-project/pull/161086