Files
project_6/cccl_upstream/libcudacxx/include/cuda/__numeric/narrow.h
EngineX CI 56fd68e7dd [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
2026-07-30 09:35:51 +00:00

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3.5 KiB
C++

//===----------------------------------------------------------------------===//
//
// Part of the libcu++ Project, 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.
//
//===----------------------------------------------------------------------===//
#ifndef _CUDA___NUMERIC_NARROW_H
#define _CUDA___NUMERIC_NARROW_H
#include <cuda/std/detail/__config>
#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 <cuda/std/__exception/exception_macros.h>
#include <cuda/std/__host_stdlib/stdexcept>
#include <cuda/std/__type_traits/is_arithmetic.h>
#include <cuda/std/__type_traits/is_constructible.h>
#include <cuda/std/__type_traits/is_signed.h>
#include <cuda/std/__utility/forward.h>
#include <cuda/std/__cccl/prologue.h>
_CCCL_BEGIN_NAMESPACE_CUDA
//! Uses static_cast to cast a value \p __from to type \p _To. \p _To needs to be constructible from \p _From, and \p
//! implement operator!=. This function is intended to show that narrowing and a potential change of the value is
//! intended. Modelled after `gsl::narrow_cast`. See also the C++ Core Guidelines <a
//! href="https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Res-narrowing">ES.46</a> and <a
//! href="https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Res-casts-named">ES.49</a>.
template <class _To, class _From>
[[nodiscard]] _CCCL_API constexpr _To
narrow_cast(_From&& __from) noexcept(noexcept(static_cast<_To>(::cuda::std::forward<_From>(__from))))
{
return static_cast<_To>(::cuda::std::forward<_From>(__from));
}
#if _CCCL_HAS_EXCEPTIONS()
struct narrowing_error : ::std::runtime_error
{
_CCCL_HOST_API narrowing_error()
: ::std::runtime_error("Narrowing error")
{}
};
#endif // _CCCL_HAS_EXCEPTIONS()
//! Uses static_cast to cast a value \p __from to type \p _To and checks whether the value has changed. \p _To needs
//! to be constructible from \p _From and vice versa, and \p implement operator!=. Throws \ref narrowing_error in host
//! code and traps in device code if the value has changed. Modelled after `gsl::narrow`. See also the C++ Core
//! Guidelines <a href="https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Res-narrowing">ES.46</a> and <a
//! href="https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Res-casts-named">ES.49</a>.
template <class _To, class _From>
[[nodiscard]] _CCCL_API constexpr _To narrow(_From __from)
{
static_assert(::cuda::std::is_constructible_v<_From, _To>);
static_assert(::cuda::std::is_constructible_v<_To, _From>);
const auto __converted = static_cast<_To>(__from);
if (static_cast<_From>(__converted) != __from)
{
_CCCL_THROW(::cuda::narrowing_error);
}
if constexpr (::cuda::std::is_arithmetic_v<_From>)
{
if constexpr (::cuda::std::is_signed_v<_From> && !::cuda::std::is_signed_v<_To>)
{
if (__from < _From{})
{
_CCCL_THROW(::cuda::narrowing_error);
}
}
if constexpr (!::cuda::std::is_signed_v<_From> && ::cuda::std::is_signed_v<_To>)
{
if (__converted < _To{})
{
_CCCL_THROW(::cuda::narrowing_error);
}
}
}
return __converted;
}
_CCCL_END_NAMESPACE_CUDA
#include <cuda/std/__cccl/epilogue.h>
#endif // _CUDA___NUMERIC_NARROW_H