How to use clCreateProgramWithBinary in OpenCL? - opencl

Question

I'm trying to just get a basic program to work using clCreateProgramWithBinary. This is so I know how to use it rather than a "true" application.
I see that one of the parameters is a list of binaries. How exactly would I go about creating a binary to test with? I have some test code which creates a program from source, builds and enqueues it. Is there a binary created at some point during this process which I can feed into clCreateProgramWithBinary?
Here is some of my code, just to give an idea of my overall flow. I've omitted comments and error checks for simplicity.
program = clCreateProgramWithSource(clctx, 1, &dumbkernelsource, NULL, &errcode);
errcode = clBuildProgram(program, env->num_devices, env->device, NULL, NULL, NULL);
mykernel = clCreateKernel(program, "flops", &errcode);
errcode = clGetKernelWorkGroupInfo(mykernel, *(env->device), CL_KERNEL_WORK_GROUP_SIZE, sizeof(local), &local, NULL);
global = num_workgroups * local;
errcode = clEnqueueNDRangeKernel(commands, mykernel, 1, NULL, &global, &local, 0, NULL, NULL);

Answer 1

After you compile your program, you can get its binary code with clGetProgramInfo, and then save it to a file.
Example code (not tried to compile, but should be something along these lines):
program = clCreateProgramWithSource(clctx, 1, &dumbkernelsource, NULL, &errcode);
errcode = clBuildProgram(program, env->num_devices, env->device, NULL, NULL, NULL);
int number_of_binaries;
char **binary;
int *binary_sizes;
errcode = clGetProgramInfo(program, CL_PROGRAM_BINARY_SIZES, NULL, 0, &number_of_binaries);
binary_sizes = new int[number_of_binaries];
binary = new char*[number_of_binaries];
errcode = clGetProgramInfo(program, CL_PROGRAM_BINARY_SIZES, binary_sizes, number_of_binaries*sizeof(int), &number_of_binaries);
for (int i = 0; i < number_of_binaries; ++i) binary[i] = new char[binary_sizes[i]];
errcode = clGetProgramInfo(program, CL_PROGRAM_BINARIES, binary, number_of_binaries*sizeof(char*), &number_of_binaries);

Answer 2

Minimal runnable example
Compile the embedded vector increment shader from CL C source, save the binary to a.bin, load the binary shader, and run it:
./a.out
Assertions are done at the end of the program.
Ignore the CL C shader, load binary from a.bin, and run it:
./a.out 0
Compile and run with:
gcc -ggdb3 -std=c99 -Wall -Wextra a.c -lOpenCL && ./a.out
Tested in Ubuntu 16.10, NVIDIA NVS5400, driver 375.39.
GitHub upstream: https://github.com/cirosantilli/cpp-cheat/blob/b1e9696cb18a12c4a41e0287695a2a6591b04597/opencl/binary_shader.c
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define CL_USE_DEPRECATED_OPENCL_1_2_APIS
#include <CL/cl.h>
const char *source =
"__kernel void kmain(__global int *out) {\n"
" out[get_global_id(0)]++;\n"
"}\n"
;
#define BIN_PATH "a.bin"
char* common_read_file(const char *path, long *length_out) {
char *buffer;
FILE *f;
long length;
f = fopen(path, "r");
assert(NULL != f);
fseek(f, 0, SEEK_END);
length = ftell(f);
fseek(f, 0, SEEK_SET);
buffer = malloc(length);
if (fread(buffer, 1, length, f) < (size_t)length) {
return NULL;
}
fclose(f);
if (NULL != length_out) {
*length_out = length;
}
return buffer;
}
int main(int argc, char **argv) {
FILE *f;
char *binary;
cl_command_queue command_queue;
cl_context context;
cl_device_id device;
cl_int input[] = {1, 2}, errcode_ret, binary_status;
cl_kernel kernel, binary_kernel;
cl_mem buffer;
cl_platform_id platform;
cl_program program, binary_program;
const size_t global_work_size = sizeof(input) / sizeof(input[0]);
int use_cache;
long lenght;
size_t binary_size;
if (argc > 1) {
use_cache = !strcmp(argv[1], "0");
} else {
use_cache = 0;
}
/* Get the binary, and create a kernel with it. */
clGetPlatformIDs(1, &platform, NULL);
clGetDeviceIDs(platform, CL_DEVICE_TYPE_ALL, 1, &device, NULL);
context = clCreateContext(NULL, 1, &device, NULL, NULL, NULL);
command_queue = clCreateCommandQueue(context, device, 0, NULL);
if (use_cache) {
binary = common_read_file(BIN_PATH, &lenght);
binary_size = lenght;
} else {
program = clCreateProgramWithSource(context, 1, &source, NULL, NULL);
clBuildProgram(program, 1, &device, "", NULL, NULL);
kernel = clCreateKernel(program, "kmain", NULL);
clGetProgramInfo(program, CL_PROGRAM_BINARY_SIZES, sizeof(size_t), &binary_size, NULL);
binary = malloc(binary_size);
clGetProgramInfo(program, CL_PROGRAM_BINARIES, binary_size, &binary, NULL);
f = fopen(BIN_PATH, "w");
fwrite(binary, binary_size, 1, f);
fclose(f);
}
binary_program = clCreateProgramWithBinary(
context, 1, &device, &binary_size,
(const unsigned char **)&binary, &binary_status, &errcode_ret
);
free(binary);
clBuildProgram(binary_program, 1, &device, NULL, NULL, NULL);
binary_kernel = clCreateKernel(binary_program, "kmain", &errcode_ret);
/* Run the kernel created from the binary. */
buffer = clCreateBuffer(context, CL_MEM_READ_WRITE | CL_MEM_COPY_HOST_PTR, sizeof(input), input, NULL);
clSetKernelArg(binary_kernel, 0, sizeof(buffer), &buffer);
clEnqueueNDRangeKernel(command_queue, binary_kernel, 1, NULL, &global_work_size, NULL, 0, NULL, NULL);
clFlush(command_queue);
clFinish(command_queue);
clEnqueueReadBuffer(command_queue, buffer, CL_TRUE, 0, sizeof(input), input, 0, NULL, NULL);
/* Assertions. */
assert(input[0] == 2);
assert(input[1] == 3);
/* Cleanup. */
clReleaseMemObject(buffer);
clReleaseKernel(kernel);
clReleaseKernel(binary_kernel);
clReleaseProgram(program);
clReleaseProgram(binary_program);
clReleaseCommandQueue(command_queue);
clReleaseContext(context);
return EXIT_SUCCESS;
}
I highly recommend cat a.bin, which contains human readable (and editable) PTX assembly for this implementation.

Answer 3

The official OpenCL Programming Guide book has a nice example of this. There's also a Google code project, opencl-book-samples, which includes the code from the book. The example you're looking for is here.