fix(hip): load dispatch table slots atomically in the entry points

projects/clr/hipamd/src/hip_dispatch_load.hpp

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) Advanced Micro Devices, Inc., or its affiliates.
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <type_traits>
+#if defined(_WIN32)
+#include <atomic>
+#endif
+
+namespace hip {
+
+// Loads one function-pointer slot of a live HIP dispatch table.
+//
+// Tools such as HRR capture write slots of the live table while other threads call
+// through it. Each write is a single release store of one aligned pointer (see
+// install_shims in hrr/hip_capture.cpp). The HIP entry points in hip_table_interface.cpp
+// read each slot with the matching acquire load, so a caller gets either the old function
+// or the new one, and the new function sees everything its tool wrote before installing
+// it. An acquire load of a pointer is a plain load on x86-64 and LDAR on AArch64.
+template <typename Fn> inline Fn LoadDispatchSlot(const Fn& slot) {
+  static_assert(std::is_pointer_v<Fn> && sizeof(Fn) == sizeof(void*),
+                "dispatch slots are function pointers the size of void*");
+#if defined(_WIN32)
+  // Same view as the Windows store in hrr/hip_capture.cpp.
+  void*& raw = reinterpret_cast<void*&>(const_cast<Fn&>(slot));
+  return reinterpret_cast<Fn>(std::atomic_ref<void*>(raw).load(std::memory_order_acquire));
+#else
+  return __atomic_load_n(&slot, __ATOMIC_ACQUIRE);
+#endif
+}
+
+}  // namespace hip