OpenCL clBuildProgram fails on AMD GPU on OS X with non-descriptive build log

Question

I'm trying to compile a set of OpenCL kernels in a C++ project on OS X El Capitan 10.11.2.

The machine used is a iMac (Retina 5K, 27-inch, Late 2015), containing a AMD Radeon R9 M395X 4096 MB that is chosen as the OpenCL device. I'm using the OpenCL framework that ships with the OS.

On a particular kernel, the OpenCL program build fails with this CL_PROGRAM_BUILD_LOG:

SC failed. No reason given.

The same kernels compile fine when choosing the CPU of the same machine as an OpenCL device or a similar machine with an Nvidia GPU.

Community · Accepted Answer · 2017-05-23 10:31:11Z

3

The problematic kernel source can be boiled down to the following:

kernel void sampleKernel (bool param) {}

Using a bool as a parameter of an OpenCL kernel is not supported by the OpenCL C specification, see e.g. https://stackoverflow.com/a/4441865/463796

Replacing the type of the parameter with a char solves the problem.

edited May 23, 2017 at 10:31

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answered Dec 11, 2015 at 11:30

w-m

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2 Comments

DarkZeros Over a year ago

It is not that the OpenCL spec (specifically) does not support bool. Is that OpenCL kernels are C99, and C99 (plain C) does not support booleans, if other compiler do support it they are not meeting the spec. Also be careful, because booleans are not required to be chars, although they are in most cases.

w-m Over a year ago

Although OpenCL C is based on C99, data types are the area where they are different. OpenCL C does support a bool type in kernel code, but does indeed explicitly disallow passing a bool as a kernel parameter. Still some compilers do (wrongly) support it.

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