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project_6/cccl_upstream/cudax/test/stf/examples/09-nbody-algorithm.cu
muh-bot dedf08166a [CCCL] Add missing CCCL components: c2h, nvbench_helper, cmake, cudax, AGENTS.md
Added 863 files from NVIDIA/cccl sparse checkout:
- c2h/ (27 files): Catch2 test helpers — generators, validators, runner
- nvbench_helper/ (10 files): Benchmark harness utilities
- cmake/ (29 files): CMake presets and build helpers
- cudax/ (794 files): Experimental CUDA extensions
- AGENTS.md: NVIDIA's official AI agent instructions for CCCL
- CMakePresets.json: Standardized build configurations
- cccl-version.json: Version tracking

Also added CCCL_ASSET_MAP.md mapping all 4295 CCCL files to
competition value and PRD items.

cccl_upstream now covers 100% of competition-critical assets:
- 27 tuning headers (SM80/90/100 benchmark data)
- 32 dispatch headers (algorithm implementations)
- 60 Thrust examples (correctness verification)
- 217 CUB Catch2 tests (regression matrix)
- 153 CUB benchmarks (parameter space search)
- 18 CUB examples (API verification)
- 27 test helpers + benchmark harness
- 794 cudax experimental extensions
2026-08-06 02:14:18 +00:00

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//===----------------------------------------------------------------------===//
//
// Part of CUDASTF 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) 2022-2024 NVIDIA CORPORATION & AFFILIATES.
//
//===----------------------------------------------------------------------===//
#include <cuda/experimental/stf.cuh>
#include <random>
using namespace cuda::experimental::stf;
struct body
{
// mass
double mass;
// position
double pos[3];
// speed
double vel[3];
// acceleration
double acc[3];
};
int main()
{
constexpr double kSofteningSquared = 1e-3;
constexpr double kG = 6.67259e-11;
size_t BODY_CNT = 4096;
double dt = 0.1;
size_t NITER = 25;
context ctx;
std::vector<body> particles;
particles.resize(BODY_CNT);
// Initialize particles
std::random_device rd;
std::mt19937 gen(rd());
std::uniform_real_distribution<> dis(-1.0, 1.0);
for (auto& p : particles)
{
p.mass = 1.0;
p.pos[0] = dis(gen);
p.pos[1] = dis(gen);
p.pos[2] = dis(gen);
p.vel[0] = dis(gen);
p.vel[1] = dis(gen);
p.vel[2] = dis(gen);
p.acc[0] = 0.0;
p.acc[1] = 0.0;
p.acc[2] = 0.0;
}
auto h_particles = ctx.logical_data(make_slice(&particles[0], BODY_CNT));
auto fn = [dt](context ctx, logical_data<slice<body>> h_particles) {
// Compute accelerations
ctx.parallel_for(h_particles.shape(), h_particles.rw())->*[=] _CCCL_DEVICE __host__(size_t i, slice<body> p) {
double acc[3];
for (size_t k = 0; k < 3; k++)
{
acc[k] = p(i).acc[k];
}
for (size_t j = 0; j < p.extent(0); j++)
{
if (i != j)
{
double d[3];
for (size_t k = 0; k < 3; k++)
{
d[k] = p(j).pos[k] - p(i).pos[k];
}
double dist = d[0] * d[0] + d[1] * d[1] + d[2] * d[2] + kSofteningSquared;
double dist_inv = 1.0 / sqrt(dist);
for (size_t k = 0; k < 3; k++)
{
acc[k] += d[k] * kG * p(j).mass * dist_inv * dist_inv * dist_inv;
}
}
}
for (size_t k = 0; k < 3; k++)
{
p(i).acc[k] = acc[k];
}
};
// Update velocity and positions
ctx.parallel_for(h_particles.shape(), h_particles.rw())->*[=] __host__ __device__(size_t i, slice<body> p) {
for (size_t k = 0; k < 3; k++)
{
p(i).vel[k] += p(i).acc[k] * dt;
}
for (size_t k = 0; k < 3; k++)
{
p(i).pos[k] += p(i).vel[k] * dt;
}
for (size_t k = 0; k < 3; k++)
{
p(i).acc[k] = 0.0;
}
};
};
algorithm one_iter;
for (size_t iter = 0; iter < NITER; iter++)
{
// fprintf(stderr, "ITER %ld\n", iter);
one_iter.run_as_task(fn, ctx, h_particles.rw());
}
ctx.finalize();
}