topic Bruce, in OpenCL* for CPU

clSetKernelArg bug for 3 arguments

Bruce_M_ — Fri, 05 Oct 2012 08:08:50 GMT

I've found a bug in the 2013 beta Linux build: when using clSetKernelArg to set an int3 argument, it fails if sizeof(cl_int3) is used as the size. It accepts 3 * sizeof(cl_int), but the CL spec is pretty clear that the API type corresponding to int3 is cl_int3, not cl_int[3] (there's a table at the start of section 6.1.2 in the CL 1.1 spec). The sizes are different because cl_int3 is padded to 4*sizeof(cl_int).

Both the NVIDIA and AMD OpenCL implementations expect the size to be sizeof(cl_int3).

Bruce,

Raghupathi_M_Intel — Sat, 06 Oct 2012 00:09:20 GMT

Bruce, I don't think that's a bug. The spec clearly says this about sizeof - "When applied to an operand that is a vector type, the result is number of components * size of each scalar component (Except for 3-component vectors whose size is defined as 4 * size of each scalar component.)". So it appears that Intel's behavior is correct. Thanks, Raghu

Quote:Raghupathi

Bruce_M_ — Sat, 06 Oct 2012 07:14:37 GMT

Raghupathi Muthyalampalli (Intel) wrote:
Bruce,

"When applied to an operand that is a vector type, the result is number of components * size of each scalar component (Except for 3-component vectors whose size is defined as 4 * size of each scalar component.)"

Actually I think the part in parentheses supports my point: the size of an int3 is 16, not 12, yet clSetKernelArg only works when I pass a size of 12.

Ah sorry. I thought your

Raghupathi_M_Intel — Mon, 08 Oct 2012 16:25:30 GMT

Ah sorry. I thought your original post said the opposite. Can you attach a small test case? Thanks, Raghu

I've written and attached a

Bruce_M_ — Tue, 09 Oct 2012 08:09:58 GMT

I've written and attached a testcase that uses CLU. I included the CLU runtime in the zipfile, which I had to edit slightly to get it to compile with GCC. When I run it, it outputs intel_sizeof.c:50: clSetKernelArg(kernel, 0, sizeof(arg), &arg) failed: -51 and -51 is CL_INVALID_ARG_SIZE.