shims: add a new HAVE_WAIT_ON_ADDRESS and adopt in locks

This introduces a new `HAVE_WAIT_ON_ADDRESS` which is the equivalent to
`HAVE_FUTEX` on Linux.  Extend the other sites to use this rather than
`defined(_WIN32)`.  This identified a couple of additional sites that
required updating which is included in this change now.

Author: compnerd

src/shims/lock.c

@@ -507,7 +507,7 @@ _dispatch_wait_on_address(uint32_t volatile *_address, uint32_t value,
 		return _dispatch_futex_wait(address, value, &ts, FUTEX_PRIVATE_FLAG);
 	}
 	return _dispatch_futex_wait(address, value, NULL, FUTEX_PRIVATE_FLAG);
-#elif defined(_WIN32)
+#elif HAVE_WAIT_ON_ADDRESS
 	return WaitOnAddress(address, &value, sizeof(value), INFINITE) == TRUE;
 #else
 #error _dispatch_wait_on_address unimplemented for this platform
@@ -521,7 +521,7 @@ _dispatch_wake_by_address(uint32_t volatile *address)
 	_dispatch_ulock_wake((uint32_t *)address, ULF_WAKE_ALL);
 #elif HAVE_FUTEX
 	_dispatch_futex_wake((uint32_t *)address, INT_MAX, FUTEX_PRIVATE_FLAG);
-#elif defined(_WIN32)
+#elif HAVE_WAIT_ON_ADDRESS
 	WakeByAddressAll((uint32_t *)address);
 #else
 	(void)address;
@@ -537,6 +537,8 @@ _dispatch_thread_event_signal_slow(dispatch_thread_event_t dte)
 	_dispatch_ulock_wake(&dte->dte_value, 0);
 #elif HAVE_FUTEX
 	_dispatch_futex_wake(&dte->dte_value, 1, FUTEX_PRIVATE_FLAG);
+#elif HAVE_WAIT_ON_ADDRESS
+	WakeByAddressSingle(&dte->dte_value);
 #else
 	_dispatch_sema4_signal(&dte->dte_sema, 1);
 #endif
@@ -545,7 +547,7 @@ _dispatch_thread_event_signal_slow(dispatch_thread_event_t dte)
 void
 _dispatch_thread_event_wait_slow(dispatch_thread_event_t dte)
 {
-#if HAVE_UL_COMPARE_AND_WAIT || HAVE_FUTEX
+#if HAVE_UL_COMPARE_AND_WAIT || HAVE_FUTEX || HAVE_WAIT_ON_ADDRESS
 	for (;;) {
 		uint32_t value = os_atomic_load(&dte->dte_value, acquire);
 		if (likely(value == 0)) return;
@@ -558,6 +560,8 @@ _dispatch_thread_event_wait_slow(dispatch_thread_event_t dte)
 #elif HAVE_FUTEX
 		_dispatch_futex_wait(&dte->dte_value, UINT32_MAX,
 				NULL, FUTEX_PRIVATE_FLAG);
+#elif HAVE_WAIT_ON_ADDRESS
+		WaitOnAddress(&dte->dte_value, &value, sizeof(value), INFINITE);
 #endif
 	}
 #else

src/shims/lock.h

@@ -174,6 +174,14 @@ _dispatch_lock_has_failed_trylock(dispatch_lock lock_value)
 #endif
 #endif // HAVE_FUTEX
 
+#ifndef HAVE_WAIT_ON_ADDRESS
+#if defined(_WIN32)
+#define HAVE_WAIT_ON_ADDRESS 1
+#else
+#define HAVE_WIAT_ON_ADDRESS 0
+#endif
+#endif
+
 #if defined(__x86_64__) || defined(__i386__) || defined(__s390x__)
 #define DISPATCH_ONCE_USE_QUIESCENT_COUNTER 0
 #elif __APPLE__
@@ -271,7 +279,7 @@ void _dispatch_wake_by_address(uint32_t volatile *address);
  * This locking primitive has no notion of ownership
  */
 typedef struct dispatch_thread_event_s {
-#if HAVE_UL_COMPARE_AND_WAIT || HAVE_FUTEX
+#if HAVE_UL_COMPARE_AND_WAIT || HAVE_FUTEX || HAVE_WAIT_ON_ADDRESS
 	// 1 means signalled but not waited on yet
 	// UINT32_MAX means waited on, but not signalled yet
 	// 0 is the initial and final state
@@ -289,7 +297,7 @@ DISPATCH_ALWAYS_INLINE
 static inline void
 _dispatch_thread_event_init(dispatch_thread_event_t dte)
 {
-#if HAVE_UL_COMPARE_AND_WAIT || HAVE_FUTEX
+#if HAVE_UL_COMPARE_AND_WAIT || HAVE_FUTEX || HAVE_WAIT_ON_ADDRESS
 	dte->dte_value = 0;
 #else
 	_dispatch_sema4_init(&dte->dte_sema, _DSEMA4_POLICY_FIFO);
@@ -300,7 +308,7 @@ DISPATCH_ALWAYS_INLINE
 static inline void
 _dispatch_thread_event_signal(dispatch_thread_event_t dte)
 {
-#if HAVE_UL_COMPARE_AND_WAIT || HAVE_FUTEX
+#if HAVE_UL_COMPARE_AND_WAIT || HAVE_FUTEX || HAVE_WAIT_ON_ADDRESS
 	if (os_atomic_add_orig(&dte->dte_value, 1u, release) == 0) {
 		// 0 -> 1 transition doesn't need a signal
 		// force a wake even when the value is corrupt,
@@ -318,7 +326,7 @@ DISPATCH_ALWAYS_INLINE
 static inline void
 _dispatch_thread_event_wait(dispatch_thread_event_t dte)
 {
-#if HAVE_UL_COMPARE_AND_WAIT || HAVE_FUTEX
+#if HAVE_UL_COMPARE_AND_WAIT || HAVE_FUTEX || HAVE_WAIT_ON_ADDRESS
 	if (os_atomic_sub(&dte->dte_value, 1u, acquire) == 0) {
 		// 1 -> 0 is always a valid transition, so we can return
 		// for any other value, take the slow path which checks it's not corrupt
@@ -334,7 +342,7 @@ DISPATCH_ALWAYS_INLINE
 static inline void
 _dispatch_thread_event_destroy(dispatch_thread_event_t dte)
 {
-#if HAVE_UL_COMPARE_AND_WAIT || HAVE_FUTEX
+#if HAVE_UL_COMPARE_AND_WAIT || HAVE_FUTEX || HAVE_WAIT_ON_ADDRESS
 	// nothing to do
 	dispatch_assert(dte->dte_value == 0);
 #else