[INFRA] Import NVIDIA/CCCL upstream as optimization reference library

CCCL (CUDA C++ Core Libraries) provides:
- CUB: device/block/warp-level GPU primitives (reduce, scan, sort, topk)
- Thrust: high-level parallel algorithms (transform_reduce, sort, scan)
- libcudacxx: CUDA C++ standard library (atomics, barriers, memory)
- cudax: experimental features (memory resources, allocators)
- Tuning policies: per-SM hardware-specific algorithm parameters

Competition optimization vectors mapped to CCCL:
- Output TPS (83% weight): warp_reduce, block_reduce, device_topk
- Input TPS (14% weight): device_scan, block_load, prefetch
- Cache TPS (3% weight): prefix caching strategy patterns
- Memory (0.9 util): pooled/cached/buddy allocators

Source: https://github.com/NVIDIA/cccl (shallow clone, HEAD only)
License: Apache-2.0

cccl_upstream/cudax/test/cufile/cufile_ref.cu

@@ -0,0 +1,69 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of CUDA Experimental in CUDA C++ Core Libraries,
+// under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+// SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES.
+//
+//===----------------------------------------------------------------------===//
+
+#include <cuda/std/type_traits>
+#include <cuda/std/utility>
+
+#include <cuda/experimental/cufile.cuh>
+
+#include <cufile.h>
+#include <testing.cuh>
+
+#include "common.h"
+
+C2H_CCCLRT_TEST("cuFile cufile_ref", "[cufile][cufile]")
+{
+  constexpr auto filename = "cufile_ref_test_file";
+
+  // 1. Test public cufile_ref types and properties.
+  STATIC_REQUIRE(cuda::std::is_same_v<cudax::cufile_ref::off_type, ::off_t>);
+
+  // 2. Test default constructor.
+  STATIC_REQUIRE(!cuda::std::is_default_constructible_v<cudax::cufile_ref>);
+
+  // 3. Test cufile_ref(CUfileHandle_t) constructor.
+  STATIC_REQUIRE(cuda::std::is_nothrow_constructible_v<cudax::cufile_ref, CUfileHandle_t>);
+  STATIC_REQUIRE(cuda::std::is_convertible_v<CUfileHandle_t, cudax::cufile_ref>);
+  {
+    cudax::cufile file{filename, cudax::cufile_open_mode::out};
+
+    cudax::cufile_ref file_ref{file.get()};
+    REQUIRE(file_ref.get() == file.get());
+  }
+  test_remove_file(filename);
+
+  // 4. Test copy constructor.
+  STATIC_REQUIRE(cuda::std::is_trivially_copy_constructible_v<cudax::cufile_ref>);
+
+  // 5. Test move constructor.
+  STATIC_REQUIRE(cuda::std::is_trivially_move_constructible_v<cudax::cufile_ref>);
+
+  // 6. Test copy assignment.
+  STATIC_REQUIRE(cuda::std::is_trivially_copy_assignable_v<cudax::cufile_ref>);
+
+  // 7. Test move assignment.
+  STATIC_REQUIRE(cuda::std::is_trivially_move_assignable_v<cudax::cufile_ref>);
+
+  // 8. Test destructor.
+  STATIC_REQUIRE(cuda::std::is_trivially_destructible_v<cudax::cufile_ref>);
+
+  // 9. Test get().
+  STATIC_REQUIRE(noexcept(cuda::std::declval<cudax::cufile_ref>().get()));
+  STATIC_REQUIRE(cuda::std::is_same_v<CUfileHandle_t, decltype(cuda::std::declval<cudax::cufile_ref>().get())>);
+  {
+    const cudax::cufile file;
+    REQUIRE(cudax::cufile_ref{file}.get() == nullptr);
+  }
+  {
+    cudax::cufile file{filename, cudax::cufile_open_mode::out};
+    REQUIRE(cudax::cufile_ref{file}.get() != nullptr);
+  }
+  test_remove_file(filename);
+}