variable length array declaration not allowed in OpenCL - why?

Question

I want to create a local array inside my OpenCL kernel, whose size depends on a parameter of the kernel. It seems that\'s not allowed - at least with AMD APP.

Is you

Answer 1

You can dynamically allocate the size of a local block. You need to take it as a parameter to your kernel, and define its size when you call clSetKernelArg.

definition example:

__kernel void kernelName(__local float* myLocalFloats, ...)

host code:

clSetKernelArg(kernel, 0, myLocalFloatCount * sizeof(float), NULL); // <-- set the size to the correct number of bytes to allocate, but use NULL for the data.

Make sure you know what the limit for local memory is on your device before you do this. Call clGetDeviceInfo, and poll for the 'CL_DEVICE_LOCAL_MEM_SIZE' value.