Building OpenCL kernel with header

OpenCL
1

I am currently trying to build kernel with a header. I use clBuildProgram and include various directories in the options parameter.

After going through several headers, the OpenCL compiler reaches the following error:

Fail to build the program
“/usr/lib/gcc/x86_64-linux-gnu/4.8/include/stdarg.h”, line 40
identifier “__builtin_va_list” is undefined
typedef __builtin_va_list __gnuc_va_list;

How do you define __builtin_va_list?

2

Something you are #include’ing is trying to #include stdarg.h, which is likely not compatible with OpenCL C99. Check your includes (and their includes) to find the culprit.

3

I suspected as much. I read somewhere that the OpenCL compiler had troubles with system header files, but I was hoping a second opinion would prove me wrong. I am using OpenCL 1.2, but is it safe to assume that it doesn’t work for later versions as well?

4

Of course. For example, and system header that includes file system access, system clock access, stdio access, etc. None of these can be accessed from the device.

5

The simple fix for this is to wrap any system includes needed by the host in #ifndef OPENCL_VERSION guards, e.g.:

/* Header file shared by host and device */

#ifndef __OPENCL_VERSION__
#include <stdlib.h>
// etc
#endif

// Define shared data types
typedef struct
{
  // etc
};
6

The #ifndef OPENCL_VERSION worked in stopping the errors. However, I hit a dead-end when I reached custom types. Thanks for the inputs.