cuda-samples/Samples/7_libNVVM/simple/simple.c

// Copyright (c) 1993-2023, NVIDIA CORPORATION. All rights reserved.
//
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#include <assert.h>
#include <builtin_types.h>
#include <cuda.h>
#include <math.h>
#include <nvvm.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>

// If 'err' is non-zero, emit an error message and exit.
#define checkCudaErrors(err) __checkCudaErrors(err, __FILE__, __LINE__)
static void __checkCudaErrors(CUresult err, const char *filename, int line) {
  assert(filename);
  if (CUDA_SUCCESS != err) {
    const char *ename = NULL;
    const CUresult res = cuGetErrorName(err, &ename);
    fprintf(stderr,
            "CUDA API Error %04d: \"%s\" from file <%s>, "
            "line %i.\n",
            err, ((CUDA_SUCCESS == res) ? ename : "Unknown"), filename, line);
    exit(err);
  }
}

// Return a CUDA capable device or exit if one cannot be found.
static CUdevice cudaDeviceInit(void) {
  CUresult err = cuInit(0);
  int deviceCount = 0;
  if (CUDA_SUCCESS == err)
    checkCudaErrors(cuDeviceGetCount(&deviceCount));
  if (deviceCount == 0) {
    fprintf(stderr, "cudaDeviceInit error: no devices supporting CUDA\n");
    exit(EXIT_FAILURE);
  }

  // Locate a CUDA supporting device and its name.
  CUdevice cuDevice = 0;
  checkCudaErrors(cuDeviceGet(&cuDevice, 0));
  char name[128];
  cuDeviceGetName(name, sizeof(name), cuDevice);
  printf("Using CUDA Device [0]: %s\n", name);

  // Obtain the device's compute capability.
  int major = 0;
  checkCudaErrors(cuDeviceGetAttribute(
      &major, CU_DEVICE_ATTRIBUTE_COMPUTE_CAPABILITY_MAJOR, cuDevice));
  if (major < 5) {
    fprintf(stderr, "Device 0 is not sm_50 or later\n");
    exit(EXIT_FAILURE);
  }
  return cuDevice;
}

static CUresult initCUDA(CUcontext *phContext, CUdevice *phDevice,
                         CUmodule *phModule, CUfunction *phKernel,
                         const char *ptx) {
  assert(phContext && phDevice && phModule && phKernel && ptx);

  // Initialize.
  *phDevice = cudaDeviceInit();

  // Create a CUDA context on the device.
  checkCudaErrors(cuCtxCreate(phContext, 0, *phDevice));

  // Load the PTX.
  checkCudaErrors(cuModuleLoadDataEx(phModule, ptx, 0, 0, 0));

  // Locate the kernel entry point.
  checkCudaErrors(cuModuleGetFunction(phKernel, *phModule, "simple"));

  return CUDA_SUCCESS;
}

static char *loadProgramSource(const char *filename, size_t *size) {
  assert(filename && size);
  char *source = NULL;
  *size = 0;
  FILE *fh = fopen(filename, "rb");
  if (fh) {
    struct stat statbuf;
    stat(filename, &statbuf);
    source = malloc(statbuf.st_size + 1);
    assert(source);
    fread(source, statbuf.st_size, 1, fh);
    source[statbuf.st_size] = 0;
    *size = statbuf.st_size + 1;
  } else {
    fprintf(stderr, "Error reading file %s\n", filename);
    exit(EXIT_FAILURE);
  }
  return source;
}

static char *generatePTX(const char *ir, size_t size, const char *filename) {
  assert(ir && filename);

  // Create a program instance for use with libNVVM.
  nvvmProgram program;
  nvvmResult result = nvvmCreateProgram(&program);
  if (result != NVVM_SUCCESS) {
    fprintf(stderr, "nvvmCreateProgram: Failed\n");
    exit(EXIT_FAILURE);
  }

  // Add the NVVM IR to the program instance.
  result = nvvmAddModuleToProgram(program, ir, size, filename);
  if (result != NVVM_SUCCESS) {
    fprintf(stderr, "nvvmAddModuleToProgram: Failed\n");
    exit(EXIT_FAILURE);
  }

  // Compile the NVVM IR into PTX.
  result = nvvmCompileProgram(program, 0, NULL);
  if (result != NVVM_SUCCESS) {
    fprintf(stderr, "nvvmCompileProgram: Failed\n");
    size_t logSize;
    nvvmGetProgramLogSize(program, &logSize);
    char *msg = malloc(logSize);
    assert(msg);
    nvvmGetProgramLog(program, msg);
    fprintf(stderr, "%s\n", msg);
    free(msg);
    exit(EXIT_FAILURE);
  }

  // Obrain the resulting PTX.
  size_t ptxSize;
  result = nvvmGetCompiledResultSize(program, &ptxSize);
  if (result != NVVM_SUCCESS) {
    fprintf(stderr, "nvvmGetCompiledResultSize: Failed\n");
    exit(EXIT_FAILURE);
  }
  char *ptx = malloc(ptxSize);
  assert(ptx);
  result = nvvmGetCompiledResult(program, ptx);
  if (result != NVVM_SUCCESS) {
    fprintf(stderr, "nvvmGetCompiledResult: Failed\n");
    free(ptx);
    exit(EXIT_FAILURE);
  }

  // Cleanup the libNVVM program instance.
  result = nvvmDestroyProgram(&program);
  if (result != NVVM_SUCCESS) {
    fprintf(stderr, "nvvmDestroyProgram: Failed\n");
    free(ptx);
    exit(EXIT_FAILURE);
  }

  return ptx;
}

int main(int argc, char **argv) {
  const unsigned int nThreads = 32;
  const unsigned int nBlocks = 1;
  const size_t memSize = nThreads * nBlocks * sizeof(int);
  const char *filename = "simple-gpu64.ll";

  // Retrieve the NVVM IR from filename and create the kernel parameters.
  size_t size = 0;
  char *ir = loadProgramSource(filename, &size);
  fprintf(stdout, "NVVM IR (.ll) file loaded\n");

  // Use libNVVM to generate PTX from the NVVM IR.
  char *ptx = generatePTX(ir, size, filename);
  fprintf(stdout, "PTX generated:\n");
  fprintf(stdout, "%s\n", ptx);

  // Initialize the device and get a handle to the kernel.
  CUcontext hContext = 0;
  CUdevice hDevice = 0;
  CUmodule hModule = 0;
  CUfunction hKernel = 0;
  checkCudaErrors(initCUDA(&hContext, &hDevice, &hModule, &hKernel, ptx));

  // Allocate memory on the host and device.
  int *hData = malloc(memSize);
  if (!hData) {
    fprintf(stderr, "Could not allocate host memory\n");
    exit(EXIT_FAILURE);
  }
  CUdeviceptr dData = 0;
  checkCudaErrors(cuMemAlloc(&dData, memSize));

  // Launch the kernel.
  void *params[] = {&dData};
  checkCudaErrors(cuLaunchKernel(hKernel, nBlocks, 1, 1, nThreads, 1, 1, 0,
                                 NULL, params, NULL));
  fprintf(stdout, "CUDA kernel launched\n");

  // Copy the result back to the host.
  checkCudaErrors(cuMemcpyDtoH(hData, dData, memSize));

  // Print the result.
  for (unsigned i = 0; i < nBlocks * nThreads; i++)
    fprintf(stdout, "%d ", hData[i]);
  fprintf(stdout, "\n");

  // Cleanup.
  if (dData)
    checkCudaErrors(cuMemFree(dData));
  if (hModule)
    checkCudaErrors(cuModuleUnload(hModule));
  if (hContext)
    checkCudaErrors(cuCtxDestroy(hContext));
  free(hData);
  free(ir);
  free(ptx);

  return 0;
}