56fd68e7dd
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
95 lines
4.2 KiB
C++
95 lines
4.2 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of libcu++, the C++ Standard Library for your entire system,
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// under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES.
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//
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//===----------------------------------------------------------------------===//
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#ifndef __CUDA___EXECUTION_GUARANTEE_H
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#define __CUDA___EXECUTION_GUARANTEE_H
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#include <cuda/std/detail/__config>
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#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
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# pragma GCC system_header
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#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
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# pragma clang system_header
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#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
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# pragma system_header
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#endif // no system header
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#include <cuda/std/__concepts/concept_macros.h>
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#include <cuda/std/__execution/env.h>
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#include <cuda/std/__type_traits/is_base_of.h>
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#include <cuda/std/__type_traits/is_nothrow_copy_constructible.h>
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#include <cuda/std/__cccl/prologue.h>
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_CCCL_BEGIN_NAMESPACE_CUDA_EXECUTION
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// Base class of all guarantees that can be passed to cuda::execution::guarantee.
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//
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// A guarantee is a promise that the caller makes to an algorithm about its input or the problem being solved (e.g. an
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// upper bound on the total number of items). Algorithms may exploit guarantees to select faster code paths or smaller
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// intermediate types, but they are never required to. This is the dual of cuda::execution::__requirement, which
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// describes a property that the caller demands from the algorithm. Unlike requirements, guarantees may be stateful,
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// i.e. they may carry a runtime value.
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class __guarantee
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{};
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// Query used by algorithms to extract the environment of bundled guarantees from an environment assembled by
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// cuda::execution::guarantee.
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struct __get_guarantees_t
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{
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_CCCL_EXEC_CHECK_DISABLE
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_CCCL_TEMPLATE(class _Env)
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_CCCL_REQUIRES(::cuda::std::execution::__queryable_with<_Env, __get_guarantees_t>)
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[[nodiscard]] _CCCL_NODEBUG_API constexpr auto operator()(const _Env& __env) const noexcept
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{
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static_assert(noexcept(__env.query(*this)), "Guarantees must be queryable without throwing");
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return __env.query(*this);
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}
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// Answering the forwarding_query query with true makes __get_guarantees_t a forwarding query: environment adaptors
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// pass it through to the environments they wrap, so guarantees stay visible to the algorithm no matter how deeply
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// the environment carrying them is nested.
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[[nodiscard]]
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_CCCL_NODEBUG_API static constexpr auto query(::cuda::std::execution::forwarding_query_t) noexcept -> bool
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{
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return true;
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}
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};
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_CCCL_GLOBAL_CONSTANT auto __get_guarantees = __get_guarantees_t{};
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//! @brief Bundles a pack of guarantees into an environment that can be passed to device-wide parallel algorithms.
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//!
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//! @param __guarantees The guarantees to bundle. Each guarantee must be nothrow copy constructible. It is stored by
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//! value, preserving any runtime state it carries.
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//! @return An environment carrying the bundled guarantees.
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// The returned property is keyed by __get_guarantees_t so that individual guarantees are only visible to algorithms
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// through the guarantees environment, mirroring how cuda::execution::require exposes requirements. The key is spelled
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// __get_guarantees_t{} rather than reusing the __get_guarantees global: odr-using the global inside this inline
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// host-device function would reference a per-TU internal-linkage object in device passes (see _CCCL_GLOBAL_CONSTANT).
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template <class... _Guarantees>
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[[nodiscard]] _CCCL_NODEBUG_API constexpr auto guarantee(_Guarantees... __guarantees) noexcept
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{
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static_assert((::cuda::std::is_base_of_v<__guarantee, _Guarantees> && ...),
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"Only guarantees can be passed to guarantee");
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static_assert((::cuda::std::is_nothrow_copy_constructible_v<_Guarantees> && ...),
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"Guarantees must be nothrow copy constructible");
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::cuda::std::execution::env<_Guarantees...> __env{__guarantees...};
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return ::cuda::std::execution::prop{__get_guarantees_t{}, __env};
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}
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_CCCL_END_NAMESPACE_CUDA_EXECUTION
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#include <cuda/std/__cccl/epilogue.h>
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#endif // __CUDA___EXECUTION_GUARANTEE_H
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