Skip to content

[libc++][NFC] atomic::wait use public API on macOS #147146

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 1 commit into
base: main
Choose a base branch
from
Open

[libc++][NFC] atomic::wait use public API on macOS #147146

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
17 changes: 6 additions & 11 deletions libcxx/src/atomic.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,10 @@
// OpenBSD has no indirect syscalls
# define _LIBCPP_FUTEX(...) futex(__VA_ARGS__)

#elif defined(__APPLE__) && defined(_LIBCPP_USE_ULOCK)

# include <os/os_sync_wait_on_address.h>

#else // <- Add other operating systems here

// Baseline needs no new headers
Expand All @@ -65,24 +69,15 @@ static void __libcpp_platform_wake_by_address(__cxx_atomic_contention_t const vo

#elif defined(__APPLE__) && defined(_LIBCPP_USE_ULOCK)

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);

// https://github.com/apple/darwin-xnu/blob/2ff845c2e033bd0ff64b5b6aa6063a1f8f65aa32/bsd/sys/ulock.h#L82
# 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) {
static_assert(sizeof(__cxx_atomic_contention_t) == 8, "Waiting on 8 bytes value");
__ulock_wait(UL_COMPARE_AND_WAIT64, const_cast<__cxx_atomic_contention_t*>(__ptr), __val, 0);
os_sync_wait_on_address(const_cast<__cxx_atomic_contention_t*>(__ptr), __val, 8, OS_SYNC_WAIT_ON_ADDRESS_NONE);
}

static void __libcpp_platform_wake_by_address(__cxx_atomic_contention_t const volatile* __ptr, bool __notify_one) {
static_assert(sizeof(__cxx_atomic_contention_t) == 8, "Waking up on 8 bytes value");
__ulock_wake(
UL_COMPARE_AND_WAIT64 | (__notify_one ? 0 : ULF_WAKE_ALL), const_cast<__cxx_atomic_contention_t*>(__ptr), 0);
os_sync_wake_by_address_all(const_cast<__cxx_atomic_contention_t*>(__ptr), 8, OS_SYNC_WAKE_BY_ADDRESS_NONE);
}

#elif defined(__FreeBSD__) && __SIZEOF_LONG__ == 8
Expand Down
Loading