1  // examples/nv/hello.cpp
 2  //
 3  // minimal nv target test - compiled with clang, NOT nvcc
 4  //
 5  // verifies:
 6  //   - clang can compile .cu files
 7  //   - nvidia-sdk headers are found
 8  //   - libcudart links correctly
 9  //   - device code executes on sm_90+
10  
11  #include <cstdio>
12  #include <cuda_runtime.h>
13  
14  // device kernel - runs on nv hardware
15  // cppcheck-suppress unusedFunction ; called via CUDA launch syntax
16  __global__ void straylight_kernel(int *result) { *result = 42; }
17  
18  // host code
19  auto main() -> int {
20    // check for nv devices
21    int device_count = 0;
22    cudaError_t error = cudaGetDeviceCount(&device_count);
23  
24    if (error != cudaSuccess) {
25      std::printf("straylight nv toolchain: no devices (driver not loaded)\n");
26      std::printf("compilation succeeded - clang handled .cu correctly\n");
27      return 0; // success - we're testing the toolchain, not the hardware
28    }
29  
30    if (device_count == 0) {
31      std::printf("straylight nv toolchain: no devices found\n");
32      std::printf("compilation succeeded - clang handled .cu correctly\n");
33      return 0;
34    }
35  
36    // allocate device memory
37    int *device_result = nullptr;
38    cudaMalloc(&device_result, sizeof(int));
39  
40    // launch kernel
41    straylight_kernel<<<1, 1>>>(device_result);
42    cudaDeviceSynchronize();
43  
44    // copy result back
45    int host_result = 0;
46    cudaMemcpy(&host_result, device_result, sizeof(int), cudaMemcpyDeviceToHost);
47  
48    // cleanup
49    cudaFree(device_result);
50  
51    if (host_result == 42) {
52      std::printf("straylight nv toolchain operational (device returned %d)\n",
53                  host_result);
54      return 0;
55    } else {
56      std::printf("straylight nv toolchain: unexpected result %d\n", host_result);
57      return 1;
58    }
59  }