[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/thrust/thrust/per_device_resource.h

@@ -0,0 +1,113 @@
+// SPDX-FileCopyrightText: Copyright (c) 2008-2013, NVIDIA Corporation. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+
+#include <thrust/detail/config.h>
+
+#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
+#  pragma GCC system_header
+#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
+#  pragma clang system_header
+#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
+#  pragma system_header
+#endif // no system header
+#include <thrust/detail/execution_policy.h>
+#include <thrust/mr/allocator.h>
+
+// Include all active backend system implementations (generic, sequential, host and device)
+#include <thrust/system/detail/generic/per_device_resource.h>
+#include <thrust/system/detail/sequential/per_device_resource.h>
+#include __THRUST_HOST_SYSTEM_ALGORITH_DETAIL_HEADER_INCLUDE(per_device_resource.h)
+#include __THRUST_DEVICE_SYSTEM_ALGORITH_DETAIL_HEADER_INCLUDE(per_device_resource.h)
+
+// Some build systems need a hint to know which files we actually include
+#if 0
+#  include <thrust/system/cpp/detail/per_device_resource.h>
+#  include <thrust/system/cuda/detail/per_device_resource.h>
+#  include <thrust/system/omp/detail/per_device_resource.h>
+#  include <thrust/system/tbb/detail/per_device_resource.h>
+#endif
+
+THRUST_NAMESPACE_BEGIN
+
+/*! Returns a global instance of \p MR for the current device of the provided system.
+ *
+ *  \tparam MR type of a memory resource to get an instance from. Must be \p DefaultConstructible.
+ *  \param system execution policy for which the resource is requested.
+ *  \return a pointer to a global instance of \p MR for the current device.
+ *
+ *  \verbatim embed:rst:leading-asterisk
+ *     .. versionadded:: 2.2.0
+ *  \endverbatim
+ */
+template <typename MR, typename DerivedPolicy>
+_CCCL_HOST MR* get_per_device_resource(const thrust::detail::execution_policy_base<DerivedPolicy>& system)
+{
+  using thrust::system::detail::generic::get_per_device_resource;
+
+  return get_per_device_resource<MR>(thrust::detail::derived_cast(thrust::detail::strip_const(system)));
+}
+
+/*! A helper allocator class that uses global per device instances of a given upstream memory resource. Requires the
+ * memory resource to be default constructible.
+ *
+ *  \tparam T the type that will be allocated by this allocator.
+ *  \tparam MR the upstream memory resource to use for memory allocation. Must derive from
+ *      \p thrust::mr::memory_resource and must be \p final.
+ *  \tparam ExecutionPolicy the execution policy of the system to be used to retrieve the resource for the current
+ * device.
+ *
+ *  \verbatim embed:rst:leading-asterisk
+ *     .. versionadded:: 2.2.0
+ *  \endverbatim
+ */
+template <typename T, typename Upstream, typename ExecutionPolicy>
+class per_device_allocator : public thrust::mr::allocator<T, Upstream>
+{
+  using base = thrust::mr::allocator<T, Upstream>;
+
+public:
+  /*! The \p rebind metafunction provides the type of an \p per_device_allocator instantiated with another type.
+   *
+   *  \tparam U the other type to use for instantiation.
+   *
+   *  \verbatim embed:rst:leading-asterisk
+   *     .. versionadded:: 2.2.0
+   *  \endverbatim
+   */
+  template <typename U>
+  struct rebind
+  {
+    /*! The alias \p other gives the type of the rebound \p per_device_allocator.
+     */
+    using other = per_device_allocator<U, Upstream, ExecutionPolicy>;
+  };
+
+  /*! Default constructor. Uses \p get_global_resource to get the global instance of \p Upstream and initializes the
+   *      \p allocator base subobject with that resource.
+   *
+   *  \verbatim embed:rst:leading-asterisk
+   *     .. versionadded:: 2.2.0
+   *  \endverbatim
+   */
+  _CCCL_HOST per_device_allocator()
+      : base(get_per_device_resource<Upstream>(ExecutionPolicy()))
+  {}
+
+  /*! Copy constructor. Copies the memory resource pointer. */
+  _CCCL_HOST_DEVICE per_device_allocator(const per_device_allocator& other)
+      : base(other)
+  {}
+
+  /*! Conversion constructor from an allocator of a different type. Copies the memory resource pointer. */
+  template <typename U>
+  _CCCL_HOST_DEVICE per_device_allocator(const per_device_allocator<U, Upstream, ExecutionPolicy>& other)
+      : base(other)
+  {}
+
+  /*! Destructor. */
+  _CCCL_HOST_DEVICE ~per_device_allocator() {}
+};
+
+THRUST_NAMESPACE_END