cl-helper.c

/*
 * Copyright (c) 2010 Andreas Kloeckner
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */




#include "cl-helper.h"
#include <string.h>




#define MAX_NAME_LEN 1000




const char *cl_error_to_str(cl_int e)
{
  switch (e)
  {
    case CL_SUCCESS: return "success";
    case CL_DEVICE_NOT_FOUND: return "device not found";
    case CL_DEVICE_NOT_AVAILABLE: return "device not available";
#if !(defined(CL_PLATFORM_NVIDIA) && CL_PLATFORM_NVIDIA == 0x3001)
    case CL_COMPILER_NOT_AVAILABLE: return "device compiler not available";
#endif
    case CL_MEM_OBJECT_ALLOCATION_FAILURE: return "mem object allocation failure";
    case CL_OUT_OF_RESOURCES: return "out of resources";
    case CL_OUT_OF_HOST_MEMORY: return "out of host memory";
    case CL_PROFILING_INFO_NOT_AVAILABLE: return "profiling info not available";
    case CL_MEM_COPY_OVERLAP: return "mem copy overlap";
    case CL_IMAGE_FORMAT_MISMATCH: return "image format mismatch";
    case CL_IMAGE_FORMAT_NOT_SUPPORTED: return "image format not supported";
    case CL_BUILD_PROGRAM_FAILURE: return "build program failure";
    case CL_MAP_FAILURE: return "map failure";

    case CL_INVALID_VALUE: return "invalid value";
    case CL_INVALID_DEVICE_TYPE: return "invalid device type";
    case CL_INVALID_PLATFORM: return "invalid platform";
    case CL_INVALID_DEVICE: return "invalid device";
    case CL_INVALID_CONTEXT: return "invalid context";
    case CL_INVALID_QUEUE_PROPERTIES: return "invalid queue properties";
    case CL_INVALID_COMMAND_QUEUE: return "invalid command queue";
    case CL_INVALID_HOST_PTR: return "invalid host ptr";
    case CL_INVALID_MEM_OBJECT: return "invalid mem object";
    case CL_INVALID_IMAGE_FORMAT_DESCRIPTOR: return "invalid image format descriptor";
    case CL_INVALID_IMAGE_SIZE: return "invalid image size";
    case CL_INVALID_SAMPLER: return "invalid sampler";
    case CL_INVALID_BINARY: return "invalid binary";
    case CL_INVALID_BUILD_OPTIONS: return "invalid build options";
    case CL_INVALID_PROGRAM: return "invalid program";
    case CL_INVALID_PROGRAM_EXECUTABLE: return "invalid program executable";
    case CL_INVALID_KERNEL_NAME: return "invalid kernel name";
    case CL_INVALID_KERNEL_DEFINITION: return "invalid kernel definition";
    case CL_INVALID_KERNEL: return "invalid kernel";
    case CL_INVALID_ARG_INDEX: return "invalid arg index";
    case CL_INVALID_ARG_VALUE: return "invalid arg value";
    case CL_INVALID_ARG_SIZE: return "invalid arg size";
    case CL_INVALID_KERNEL_ARGS: return "invalid kernel args";
    case CL_INVALID_WORK_DIMENSION: return "invalid work dimension";
    case CL_INVALID_WORK_GROUP_SIZE: return "invalid work group size";
    case CL_INVALID_WORK_ITEM_SIZE: return "invalid work item size";
    case CL_INVALID_GLOBAL_OFFSET: return "invalid global offset";
    case CL_INVALID_EVENT_WAIT_LIST: return "invalid event wait list";
    case CL_INVALID_EVENT: return "invalid event";
    case CL_INVALID_OPERATION: return "invalid operation";
    case CL_INVALID_GL_OBJECT: return "invalid gl object";
    case CL_INVALID_BUFFER_SIZE: return "invalid buffer size";
    case CL_INVALID_MIP_LEVEL: return "invalid mip level";

#if defined(cl_khr_gl_sharing) && (cl_khr_gl_sharing >= 1)
    case CL_INVALID_GL_SHAREGROUP_REFERENCE_KHR: return "invalid gl sharegroup reference number";
#endif

#ifdef CL_VERSION_1_1
    case CL_MISALIGNED_SUB_BUFFER_OFFSET: return "misaligned sub-buffer offset";
    case CL_EXEC_STATUS_ERROR_FOR_EVENTS_IN_WAIT_LIST: return "exec status error for events in wait list";
    case CL_INVALID_GLOBAL_WORK_SIZE: return "invalid global work size";
#endif

    default: return "invalid/unknown error code";
  }
}




void print_platforms_devices()
{
  // get number of platforms
  cl_uint plat_count;
  CALL_CL_GUARDED(clGetPlatformIDs, (0, NULL, &plat_count));

  // allocate memory, get list of platforms
  cl_platform_id *platforms =
    (cl_platform_id *) malloc(plat_count*sizeof(cl_platform_id));
  CHECK_SYS_ERROR(!platforms, "allocating platform array");

  CALL_CL_GUARDED(clGetPlatformIDs, (plat_count, platforms, NULL));

  // iterate over platforms
  for (cl_uint i = 0; i < plat_count; ++i)
  {
    // get platform vendor name
    char buf[MAX_NAME_LEN];
    CALL_CL_GUARDED(clGetPlatformInfo, (platforms[i], CL_PLATFORM_VENDOR,
          sizeof(buf), buf, NULL));
    printf("platform %d: vendor '%s'\n", i, buf);

    // get number of devices in platform
    cl_uint dev_count;
    CALL_CL_GUARDED(clGetDeviceIDs, (platforms[i], CL_DEVICE_TYPE_ALL,
          0, NULL, &dev_count));

    cl_device_id *devices =
      (cl_device_id *) malloc(dev_count*sizeof(cl_device_id));
    CHECK_SYS_ERROR(!devices, "allocating device array");

    // get list of devices in platform
    CALL_CL_GUARDED(clGetDeviceIDs, (platforms[i], CL_DEVICE_TYPE_ALL,
          dev_count, devices, NULL));

    // iterate over devices
    for (cl_uint j = 0; j < dev_count; ++j)
    {
      char buf[MAX_NAME_LEN];
      CALL_CL_GUARDED(clGetDeviceInfo, (devices[j], CL_DEVICE_NAME,
            sizeof(buf), buf, NULL));
      printf("  device %d: '%s'\n", j, buf);
    }

    free(devices);
  }

  free(platforms);
}




/* Read a line from stdin. C makes things simple. :)
 * From http://stackoverflow.com/a/314422/1148634
 */
char *read_a_line(void)
{
  char * line = (char *) malloc(MAX_NAME_LEN), * linep = line;
  size_t lenmax = MAX_NAME_LEN, len = lenmax;
  int c;

  if(line == NULL)
    return NULL;

  for(;;)
  {
    c = fgetc(stdin);
    if(c == EOF)
      break;

    if(--len == 0)
    {
      char *linen = (char *) realloc(linep, lenmax *= 2);
      len = lenmax;

      if(linen == NULL)
      {
        free(linep);
        return NULL;
      }
      line = linen + (line - linep);
      linep = linen;
    }

    if((*line++ = c) == '\n')
      break;
  }
  *line = '\0';
  return linep;
}




const char *CHOOSE_INTERACTIVELY = "INTERACTIVE";


#define MIN(a,b) (((a)<(b))?(a):(b))
#define MAX(a,b) (((a)>(b))?(a):(b))

void create_context_on(const char *plat_name, const char*dev_name, cl_uint idx,
    cl_context *ctx, cl_command_queue *queue, int enable_profiling)
{
  char dev_sel_buf[MAX_NAME_LEN];
  char platform_sel_buf[MAX_NAME_LEN];

  // get number of platforms
  cl_uint plat_count;
  CALL_CL_GUARDED(clGetPlatformIDs, (0, NULL, &plat_count));

  // allocate memory, get list of platform handles
  cl_platform_id *platforms =
    (cl_platform_id *) malloc(plat_count*sizeof(cl_platform_id));
  CHECK_SYS_ERROR(!platforms, "allocating platform array");
  CALL_CL_GUARDED(clGetPlatformIDs, (plat_count, platforms, NULL));

  // print menu, if requested
#ifndef CL_HELPER_FORCE_INTERACTIVE
  if (plat_name == CHOOSE_INTERACTIVELY) // yes, we want exactly that pointer
#endif
  {
    puts("Choose platform:");
    for (cl_uint i = 0; i < plat_count; ++i)
    {
      char buf[MAX_NAME_LEN];
      CALL_CL_GUARDED(clGetPlatformInfo, (platforms[i], CL_PLATFORM_VENDOR,
            sizeof(buf), buf, NULL));
      printf("[%d] %s\n", i, buf);
    }

    printf("Enter choice: ");
    fflush(stdout);

    char *sel = read_a_line();
    if (!sel)
    {
      fprintf(stderr, "error reading line from stdin");
      abort();
    }

    int sel_int = MIN(MAX(0, atoi(sel)), (int) plat_count-1);
    free(sel);

    CALL_CL_GUARDED(clGetPlatformInfo, (platforms[sel_int], CL_PLATFORM_VENDOR,
          sizeof(platform_sel_buf), platform_sel_buf, NULL));
    plat_name = platform_sel_buf;
  }

  // iterate over platforms
  for (cl_uint i = 0; i < plat_count; ++i)
  {
    // get platform name
    char buf[MAX_NAME_LEN];
    CALL_CL_GUARDED(clGetPlatformInfo, (platforms[i], CL_PLATFORM_VENDOR,
          sizeof(buf), buf, NULL));

    // does it match?
    if (!plat_name || strstr(buf, plat_name))
    {
      // get number of devices in platform
      cl_uint dev_count;
      CALL_CL_GUARDED(clGetDeviceIDs, (platforms[i], CL_DEVICE_TYPE_ALL,
            0, NULL, &dev_count));

      // allocate memory, get list of device handles in platform
      cl_device_id *devices =
        (cl_device_id *) malloc(dev_count*sizeof(cl_device_id));
      CHECK_SYS_ERROR(!devices, "allocating device array");

      CALL_CL_GUARDED(clGetDeviceIDs, (platforms[i], CL_DEVICE_TYPE_ALL,
            dev_count, devices, NULL));

      // {{{ print device menu, if requested
#ifndef CL_HELPER_FORCE_INTERACTIVE
      if (dev_name == CHOOSE_INTERACTIVELY) // yes, we want exactly that pointer
#endif
      {
        puts("Choose device:");
        for (cl_uint j = 0; j < dev_count; ++j)
        {
          char buf[MAX_NAME_LEN];
          CALL_CL_GUARDED(clGetDeviceInfo, (devices[j], CL_DEVICE_NAME,
                sizeof(buf), buf, NULL));
          printf("[%d] %s\n", j, buf);
        }

        printf("Enter choice: ");
        fflush(stdout);

        char *sel = read_a_line();
        if (!sel)
        {
          fprintf(stderr, "error reading line from stdin");
          abort();
        }

        int int_sel = MIN(MAX(0, atoi(sel)), (int) dev_count-1);
        free(sel);

        CALL_CL_GUARDED(clGetDeviceInfo, (devices[int_sel], CL_DEVICE_NAME,
              sizeof(dev_sel_buf), dev_sel_buf, NULL));
        dev_name = dev_sel_buf;
      }

      // }}}

      // iterate over devices
      for (cl_uint j = 0; j < dev_count; ++j)
      {
        // get device name
        char buf[MAX_NAME_LEN];
        CALL_CL_GUARDED(clGetDeviceInfo, (devices[j], CL_DEVICE_NAME,
              sizeof(buf), buf, NULL));

        // does it match?
        if (!dev_name || strstr(buf, dev_name))
        {
          if (idx == 0)
          {
            cl_platform_id plat = platforms[i];
            cl_device_id dev = devices[j];

            free(devices);
            free(platforms);

            // create a context
            cl_context_properties cps[3] = {
              CL_CONTEXT_PLATFORM, (cl_context_properties) plat, 0 };

            cl_int status;
            *ctx = clCreateContext(
                cps, 1, &dev, NULL, NULL, &status);
            CHECK_CL_ERROR(status, "clCreateContext");

            // create a command queue
            cl_command_queue_properties qprops = 0;
            if (enable_profiling)
              qprops |= CL_QUEUE_PROFILING_ENABLE;

            *queue = clCreateCommandQueue(*ctx, dev, qprops, &status);
            CHECK_CL_ERROR(status, "clCreateCommandQueue");

            return;
          }
          else
            --idx;
        }
      }

      free(devices);
    }
  }

  free(platforms);

  fputs("create_context_on: specified device not found.\n", stderr);
  abort();
}




char *read_file(const char *filename)
{
  FILE *f = fopen(filename, "r");
  CHECK_SYS_ERROR(!f, "read_file: opening file");

  // figure out file size
  CHECK_SYS_ERROR(fseek(f, 0, SEEK_END) < 0, "read_file: seeking to end");
  size_t size = ftell(f);

  CHECK_SYS_ERROR(fseek(f, 0, SEEK_SET) != 0,
      "read_file: seeking to start");

  // allocate memory, slurp in entire file
  char *result = (char *) malloc(size+1);
  CHECK_SYS_ERROR(!result, "read_file: allocating file contents");
  CHECK_SYS_ERROR(fread(result, 1, size, f) < size,
      "read_file: reading file contents");

  // close, return
  CHECK_SYS_ERROR(fclose(f), "read_file: closing file");
  result[size] = '\0';

  return result;
}




cl_kernel kernel_from_string(cl_context ctx,
    char const *knl, char const *knl_name, char const *options)
{
  // create an OpenCL program (may have multiple kernels)
  size_t sizes[] = { strlen(knl) };

  cl_int status;
  cl_program program = clCreateProgramWithSource(ctx, 1, &knl, sizes, &status);
  CHECK_CL_ERROR(status, "clCreateProgramWithSource");

  // build it
  status = clBuildProgram(program, 0, NULL, options, NULL, NULL);

  if (status != CL_SUCCESS)
  {
    // build failed, get build log and print it

    cl_device_id dev;
    CALL_CL_GUARDED(clGetProgramInfo, (program, CL_PROGRAM_DEVICES,
          sizeof(dev), &dev, NULL));

    size_t log_size;
    CALL_CL_GUARDED(clGetProgramBuildInfo, (program, dev, CL_PROGRAM_BUILD_LOG,
          0, NULL, &log_size));

    char *log = (char *) malloc(log_size);
    CHECK_SYS_ERROR(!log, "kernel_from_string: allocate log");

    char devname[MAX_NAME_LEN];
    CALL_CL_GUARDED(clGetDeviceInfo, (dev, CL_DEVICE_NAME,
          sizeof(devname), devname, NULL));

    CALL_CL_GUARDED(clGetProgramBuildInfo, (program, dev, CL_PROGRAM_BUILD_LOG,
          log_size, log, NULL));
    fprintf(stderr, "*** build of '%s' on '%s' failed:\n%s\n*** (end of error)\n",
        knl_name, devname, log);
    abort();
  }
  else
    CHECK_CL_ERROR(status, "clBuildProgram");

  // fish the kernel out of the program
  cl_kernel kernel = clCreateKernel(program, knl_name, &status);
  CHECK_CL_ERROR(status, "clCreateKernel");

  CALL_CL_GUARDED(clReleaseProgram, (program));

  return kernel;
}




void print_device_info(cl_device_id device)
{
  // adapted from http://graphics.stanford.edu/~yoel/notes/clInfo.c

#define LONG_PROPS \
  defn(VENDOR_ID), \
  defn(MAX_COMPUTE_UNITS), \
  defn(MAX_WORK_ITEM_DIMENSIONS), \
  defn(MAX_WORK_GROUP_SIZE), \
  defn(PREFERRED_VECTOR_WIDTH_CHAR), \
  defn(PREFERRED_VECTOR_WIDTH_SHORT), \
  defn(PREFERRED_VECTOR_WIDTH_INT), \
  defn(PREFERRED_VECTOR_WIDTH_LONG), \
  defn(PREFERRED_VECTOR_WIDTH_FLOAT), \
  defn(PREFERRED_VECTOR_WIDTH_DOUBLE), \
  defn(MAX_CLOCK_FREQUENCY), \
  defn(ADDRESS_BITS), \
  defn(MAX_MEM_ALLOC_SIZE), \
  defn(IMAGE_SUPPORT), \
  defn(MAX_READ_IMAGE_ARGS), \
  defn(MAX_WRITE_IMAGE_ARGS), \
  defn(IMAGE2D_MAX_WIDTH), \
  defn(IMAGE2D_MAX_HEIGHT), \
  defn(IMAGE3D_MAX_WIDTH), \
  defn(IMAGE3D_MAX_HEIGHT), \
  defn(IMAGE3D_MAX_DEPTH), \
  defn(MAX_SAMPLERS), \
  defn(MAX_PARAMETER_SIZE), \
  defn(MEM_BASE_ADDR_ALIGN), \
  defn(MIN_DATA_TYPE_ALIGN_SIZE), \
  defn(GLOBAL_MEM_CACHELINE_SIZE), \
  defn(GLOBAL_MEM_CACHE_SIZE), \
  defn(GLOBAL_MEM_SIZE), \
  defn(MAX_CONSTANT_BUFFER_SIZE), \
  defn(MAX_CONSTANT_ARGS), \
  defn(LOCAL_MEM_SIZE), \
  defn(ERROR_CORRECTION_SUPPORT), \
  defn(PROFILING_TIMER_RESOLUTION), \
  defn(ENDIAN_LITTLE), \
  defn(AVAILABLE), \
  defn(COMPILER_AVAILABLE),

#define STR_PROPS \
  defn(NAME), \
  defn(VENDOR), \
  defn(PROFILE), \
  defn(VERSION), \
  defn(EXTENSIONS),

#define HEX_PROPS \
  defn(SINGLE_FP_CONFIG), \
  defn(QUEUE_PROPERTIES),


  printf("---------------------------------------------------------------------\n");
  

  static struct { cl_device_info param; const char *name; } longProps[] = {
#define defn(X) { CL_DEVICE_##X, #X }
    LONG_PROPS
#undef defn
    { 0, NULL },
  };
  static struct { cl_device_info param; const char *name; } hexProps[] = {
#define defn(X) { CL_DEVICE_##X, #X }
    HEX_PROPS
#undef defn
    { 0, NULL },
  };
  static struct { cl_device_info param; const char *name; } strProps[] = {
#define defn(X) { CL_DEVICE_##X, #X }
    STR_PROPS
#undef defn
    { CL_DRIVER_VERSION, "DRIVER_VERSION" },
    { 0, NULL },
  };
  cl_int status;
  size_t size;
  char buf[65536];
  long long val; /* Avoids unpleasant surprises for some params */
  int ii;

  for (ii = 0; strProps[ii].name != NULL; ii++)
  {
    status = clGetDeviceInfo(device, strProps[ii].param, sizeof buf, buf, &size);
    if (status != CL_SUCCESS)
    {
      printf("Unable to get %s: %s!\n",
          strProps[ii].name, cl_error_to_str(status));
      continue;
    }
    if (size > sizeof buf)
    {
      printf("Large %s (%zd bytes)!  Truncating to %ld!\n",
          strProps[ii].name, size, sizeof buf);
    }
    printf("%s: %s\n",
        strProps[ii].name, buf);
  }
  printf("\n");

  status = clGetDeviceInfo(device, CL_DEVICE_TYPE, sizeof val, &val, NULL);
  if (status == CL_SUCCESS)
  {
    printf("Type: ");
    if (val & CL_DEVICE_TYPE_DEFAULT)
    {
      val &= ~CL_DEVICE_TYPE_DEFAULT;
      printf("Default ");
    }
    if (val & CL_DEVICE_TYPE_CPU)
    {
      val &= ~CL_DEVICE_TYPE_CPU;
      printf("CPU ");
    }
    if (val & CL_DEVICE_TYPE_GPU)
    {
      val &= ~CL_DEVICE_TYPE_GPU;
      printf("GPU ");
    }
    if (val & CL_DEVICE_TYPE_ACCELERATOR)
    {
      val &= ~CL_DEVICE_TYPE_ACCELERATOR;
      printf("Accelerator ");
    }
    if (val != 0) {
      printf("Unknown (0x%llx) ", val);
    }
    printf("\n");
  }
  else
  {
    printf("Unable to get TYPE: %s!\n",
        cl_error_to_str(status));
  }

  status = clGetDeviceInfo(device, CL_DEVICE_EXECUTION_CAPABILITIES,
      sizeof val, &val, NULL);
  if (status == CL_SUCCESS)
  {
    printf("EXECUTION_CAPABILITIES: ");
    if (val & CL_EXEC_KERNEL)
    {
      val &= ~CL_EXEC_KERNEL;
      printf("Kernel ");
    }
    if (val & CL_EXEC_NATIVE_KERNEL)
    {
      val &= ~CL_EXEC_NATIVE_KERNEL;
      printf("Native ");
    }
    if (val)
      printf("Unknown (0x%llx) ", val);

    printf("\n");
  }
  else
  {
    printf("Unable to get EXECUTION_CAPABILITIES: %s!\n",
        cl_error_to_str(status));
  }

  status = clGetDeviceInfo(device, CL_DEVICE_GLOBAL_MEM_CACHE_TYPE,
      sizeof val, &val, NULL);
  if (status == CL_SUCCESS)
  {
    static const char *cacheTypes[] = { "None", "Read-Only", "Read-Write" };
    static int numTypes = sizeof cacheTypes / sizeof cacheTypes[0];

    printf("GLOBAL_MEM_CACHE_TYPE: %s (%lld)\n",
        val < numTypes ? cacheTypes[val] : "???", val);
  }
  else
  {
    printf("Unable to get GLOBAL_MEM_CACHE_TYPE: %s!\n",
        cl_error_to_str(status));
  }

  status = clGetDeviceInfo(device,
      CL_DEVICE_LOCAL_MEM_TYPE, sizeof val, &val, NULL);

  if (status == CL_SUCCESS)
  {
    static const char *lmemTypes[] = { "???", "Local", "Global" };
    static int numTypes = sizeof lmemTypes / sizeof lmemTypes[0];

    printf("CL_DEVICE_LOCAL_MEM_TYPE: %s (%lld)\n",
        val < numTypes ? lmemTypes[val] : "???", val);
  }
  else
  {
    printf("Unable to get CL_DEVICE_LOCAL_MEM_TYPE: %s!\n",
        cl_error_to_str(status));
  }

  for (ii = 0; hexProps[ii].name != NULL; ii++)
  {
    status = clGetDeviceInfo(device, hexProps[ii].param, sizeof val, &val, &size);
    if (status != CL_SUCCESS)
    {
      printf("Unable to get %s: %s!\n",
          hexProps[ii].name, cl_error_to_str(status));
      continue;
    }
    if (size > sizeof val)
    {
      printf("Large %s (%zd bytes)!  Truncating to %ld!\n",
          hexProps[ii].name, size, sizeof val);
    }
    printf("%s: 0x%llx\n", hexProps[ii].name, val);
  }
  printf("\n");

  for (ii = 0; longProps[ii].name != NULL; ii++)
  {
    status = clGetDeviceInfo(device, longProps[ii].param, sizeof val, &val, &size);
    if (status != CL_SUCCESS)
    {
      printf("Unable to get %s: %s!\n",
          longProps[ii].name, cl_error_to_str(status));
      continue;
    }
    if (size > sizeof val)
    {
      printf("Large %s (%zd bytes)!  Truncating to %ld!\n",
          longProps[ii].name, size, sizeof val);
    }
    printf("%s: %lld\n", longProps[ii].name, val);
  }

  {
    size_t size;
    CALL_CL_GUARDED(clGetDeviceInfo,
        (device, CL_DEVICE_MAX_WORK_ITEM_SIZES, 0, 0, &size));

    size_t res_vec[size/sizeof(size_t)]; // C99 VLA yay!

    CALL_CL_GUARDED(clGetDeviceInfo,
        (device, CL_DEVICE_MAX_WORK_ITEM_SIZES, size, res_vec, &size));

    printf("MAX_WORK_GROUP_SIZES: "); // a tiny lie
    for (size_t i = 0; i < size/sizeof(size_t); ++i)
      printf("%zd ", res_vec[i]);
    printf("\n");
  }
  printf("---------------------------------------------------------------------\n");
}



void print_device_info_from_queue(cl_command_queue queue)
{
  cl_device_id dev;
  CALL_CL_GUARDED(clGetCommandQueueInfo,
      (queue, CL_QUEUE_DEVICE, sizeof dev, &dev, NULL));

  print_device_info(dev);
}