[libc++] Annotate barrier functions that are defined in the dylib (#148542)

This can improve code gen slightly.

Author: philnik777

libcxx/include/barrier

@@ -97,19 +97,21 @@ using __barrier_phase_t _LIBCPP_NODEBUG = uint8_t;
 
 class __barrier_algorithm_base;
 
-_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI __barrier_algorithm_base*
-__construct_barrier_algorithm_base(ptrdiff_t& __expected);
+[[__gnu__::__returns_nonnull__, __gnu__::__malloc__]] _LIBCPP_AVAILABILITY_SYNC
+    _LIBCPP_EXPORTED_FROM_ABI __barrier_algorithm_base*
+    __construct_barrier_algorithm_base(ptrdiff_t& __expected);
 
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI bool
-__arrive_barrier_algorithm_base(__barrier_algorithm_base* __barrier, __barrier_phase_t __old_phase) noexcept;
+__arrive_barrier_algorithm_base([[__gnu__::__nonnull__]] _LIBCPP_NOESCAPE __barrier_algorithm_base* __barrier,
+                                __barrier_phase_t __old_phase) noexcept;
 
-_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void
-__destroy_barrier_algorithm_base(__barrier_algorithm_base* __barrier) noexcept;
+_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void __destroy_barrier_algorithm_base(
+    [[__gnu__::__nonnull__]] _LIBCPP_NOESCAPE __barrier_algorithm_base* __barrier) noexcept;
 
 template <class _CompletionF>
 class __barrier_base {
   ptrdiff_t __expected_;
-  unique_ptr<__barrier_algorithm_base, void (*)(__barrier_algorithm_base*)> __base_;
+  unique_ptr<__barrier_algorithm_base, void (*)(_LIBCPP_NOESCAPE __barrier_algorithm_base*)> __base_;
   atomic<ptrdiff_t> __expected_adjustment_;
   _CompletionF __completion_;
   atomic<__barrier_phase_t> __phase_;

libcxx/src/barrier.cpp

@@ -60,11 +60,12 @@ class __barrier_algorithm_base {
 _LIBCPP_EXPORTED_FROM_ABI __barrier_algorithm_base* __construct_barrier_algorithm_base(ptrdiff_t& __expected) {
   return new __barrier_algorithm_base(__expected);
 }
-_LIBCPP_EXPORTED_FROM_ABI bool
-__arrive_barrier_algorithm_base(__barrier_algorithm_base* __barrier, __barrier_phase_t __old_phase) noexcept {
+_LIBCPP_EXPORTED_FROM_ABI bool __arrive_barrier_algorithm_base(
+    _LIBCPP_NOESCAPE __barrier_algorithm_base* __barrier, __barrier_phase_t __old_phase) noexcept {
   return __barrier->__arrive(__old_phase);
 }
-_LIBCPP_EXPORTED_FROM_ABI void __destroy_barrier_algorithm_base(__barrier_algorithm_base* __barrier) noexcept {
+_LIBCPP_EXPORTED_FROM_ABI void
+__destroy_barrier_algorithm_base(_LIBCPP_NOESCAPE __barrier_algorithm_base* __barrier) noexcept {
   delete __barrier;
 }