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project_6/cccl_upstream/thrust/testing/omp/reduce_intervals.cu
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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#include <thrust/functional.h>
#include <thrust/system/detail/internal/decompose.h>
#include <thrust/system/omp/detail/reduce_intervals.h>
#include <unittest/unittest.h>
// CPP reference implementation
template <typename InputIterator, typename OutputIterator, typename BinaryFunction, typename Decomposition>
void reduce_intervals(InputIterator input, OutputIterator output, BinaryFunction binary_op, Decomposition decomp)
{
using OutputType = thrust::detail::it_value_t<OutputIterator>;
using index_type = typename Decomposition::index_type;
// wrap binary_op
thrust::detail::wrapped_function<BinaryFunction, OutputType> wrapped_binary_op{binary_op};
for (index_type i = 0; i < decomp.size(); ++i, ++output)
{
InputIterator begin = input + decomp[i].begin();
InputIterator end = input + decomp[i].end();
if (begin != end)
{
OutputType sum = *begin;
++begin;
while (begin != end)
{
sum = wrapped_binary_op(sum, *begin);
++begin;
}
*output = sum;
}
}
}
void TestOmpReduceIntervalsSimple()
{
using T = int;
using Vector = thrust::device_vector<T>;
using thrust::system::detail::internal::uniform_decomposition;
using thrust::system::omp::detail::reduce_intervals;
Vector input(10, 1);
thrust::omp::tag omp_tag;
{
uniform_decomposition<int> decomp(10, 10, 1);
Vector output(decomp.size());
reduce_intervals(omp_tag, input.begin(), output.begin(), ::cuda::std::plus<T>(), decomp);
ASSERT_EQUAL(output[0], 10);
}
{
uniform_decomposition<int> decomp(10, 6, 2);
Vector output(decomp.size());
reduce_intervals(omp_tag, input.begin(), output.begin(), ::cuda::std::plus<T>(), decomp);
ASSERT_EQUAL(output[0], 6);
ASSERT_EQUAL(output[1], 4);
}
}
DECLARE_UNITTEST(TestOmpReduceIntervalsSimple);
template <typename T>
struct TestOmpReduceIntervals
{
void operator()(const size_t n)
{
using thrust::system::detail::internal::uniform_decomposition;
using thrust::system::omp::detail::reduce_intervals;
thrust::host_vector<T> h_input = unittest::random_integers<T>(n);
thrust::device_vector<T> d_input = h_input;
uniform_decomposition<size_t> decomp(n, 7, 100);
thrust::host_vector<T> h_output(decomp.size());
thrust::device_vector<T> d_output(decomp.size());
::reduce_intervals(h_input.begin(), h_output.begin(), ::cuda::std::plus<T>(), decomp);
thrust::system::omp::tag omp_tag;
reduce_intervals(omp_tag, d_input.begin(), d_output.begin(), ::cuda::std::plus<T>(), decomp);
ASSERT_EQUAL(h_output, d_output);
}
};
VariableUnitTest<TestOmpReduceIntervals, IntegralTypes> TestOmpReduceIntervalsInstance;