问如何在库达图中使用__constant__？

EN

#include <iostream>
#include <vector>

template<typename T>
__constant__ T scalar[1];

__constant__ size_t size_a[1];

template<typename T>
__global__ void set_buffer(T *buffer) {
    const size_t index = blockIdx.x*blockDim.x + threadIdx.x;
    buffer[min(index, size_a[0])] = scalar<T>[0];
}

int main(int argc, const char * argv[]) {
    cudaGraph_t graph;
    cudaGraphCreate(&graph, 0);

    cudaStream_t stream;
    cudaStreamCreate(&stream);

    const double src = 10.0;

    cudaGraphNode_t node_a;
    cudaGraphAddMemcpyNodeToSymbol(&node_a, graph, NULL, 0,
                                   scalar<double>, &src, sizeof(double),
                                   0, cudaMemcpyHostToDevice);

    const size_t length = 100; 

    cudaGraphNode_t node_b;
    cudaGraphAddMemcpyNodeToSymbol(&node_b, graph, NULL, 0,
                                   size_a, &length, sizeof(size_t),
                                   0, cudaMemcpyHostToDevice);

    double *result;
    cudaMalloc(&result, length*sizeof(double));

    cudaKernelNodeParams params;
    params.func = (void *) set_buffer<double>;
    params.gridDim = dim3(1, 1, 1);
    params.blockDim = dim3(512, 1, 1);
    params.sharedMemBytes = 0;
    params.kernelParams = {reinterpret_cast<void **> (&result)};
    params.extra = NULL;

    cudaGraphNode_t node_c;
    std::vector<cudaGraphNode_t> deps = {node_a, node_b};
    cudaGraphAddKernelNode(&node_c, graph, deps.data(), deps.size(),
                           &params);

    cudaGraphExec_t exec;
    cudaGraphInstantiate(&exec, graph, NULL, NULL, 0);

    cudaGraphLaunch(exec, stream);
    cudaStreamSynchronize(stream);

    std::vector<double> host_result(length);
    cudaMemcpy(host_result.data(),
               result, length*sizeof(double),
               cudaMemcpyDeviceToHost);

    for (size_t i = 0; i < length; i++) {
        std::cout << i << " " << host_result[i] << std::endl;
    }    
}

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