git: 9c996882b0ed - main - libcxx: Implement atomic::wait/notify using _umtx_op(2) for 64bit arches

The branch main has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=9c996882b0ed279ca314d995f2eb1d538b94e3f8

commit 9c996882b0ed279ca314d995f2eb1d538b94e3f8
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2023-01-20 02:57:26 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2023-01-24 00:52:42 +0000

    libcxx: Implement atomic::wait/notify using _umtx_op(2) for 64bit arches
    
    Only 64bit architectures can be supported this way, because libcxx
    defines __cxx_contention_t to be int64_t for FreeBSD, and 32bit arches
    do not have a kind of UMTX_OP_WAIT_INT64_PRIVATE operation.
    
    LLVM review:    https://reviews.llvm.org/D142134
    
    Tested by:      emaste
    Reviewed by:    dim, emaste, markj
    Sponsored by:   The FreeBSD Foundation
    MFC after:      1 week
    Differential revision:  https://reviews.freebsd.org/D38132
---
 contrib/llvm-project/libcxx/src/atomic.cpp | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/contrib/llvm-project/libcxx/src/atomic.cpp b/contrib/llvm-project/libcxx/src/atomic.cpp
index 250d33e98b02..e7496fa43666 100644
--- a/contrib/llvm-project/libcxx/src/atomic.cpp
+++ b/contrib/llvm-project/libcxx/src/atomic.cpp
@@ -26,6 +26,11 @@
 # define SYS_futex SYS_futex_time64
 #endif
 
+#elif defined(__FreeBSD__)
+
+#include <sys/types.h>
+#include <sys/umtx.h>
+
 #else // <- Add other operating systems here
 
 // Baseline needs no new headers
@@ -72,6 +77,22 @@ static void __libcpp_platform_wake_by_address(__cxx_atomic_contention_t const vo
                  const_cast<__cxx_atomic_contention_t*>(__ptr), 0);
 }
 
+#elif defined(__FreeBSD__) && defined(__LP64__)
+
+static void __libcpp_platform_wait_on_address(__cxx_atomic_contention_t const volatile* __ptr,
+                                              __cxx_contention_t __val)
+{
+    _umtx_op(const_cast<__cxx_atomic_contention_t*>(__ptr),
+      UMTX_OP_WAIT, __val, NULL, NULL);
+}
+
+static void __libcpp_platform_wake_by_address(__cxx_atomic_contention_t const volatile* __ptr,
+                                              bool __notify_one)
+{
+    _umtx_op(const_cast<__cxx_atomic_contention_t*>(__ptr),
+      UMTX_OP_WAKE, __notify_one ? 1 : INT_MAX, NULL, NULL);
+}
+
 #else // <- Add other operating systems here
 
 // Baseline is just a timed backoff