Invalid writes prevent valid writes

Chris_C_1 — Mon, 31 Jul 2017 23:09:54 GMT

Hi,

On the Xeon Phi, the invalid write to a[-1] prevents both the prior and subsequent writes to a[0] from occurring:

__kernel void A(__global int* a) {
  a[0] = 1;
  a[-1] = 2;
  a[0] = 3;
}

Though the programs is technically invalid, I found this inconsistency interesting, since in all other OpenCL drivers I have tested (including 4 other Intel drivers), the write to a[-1] will not affect the final result of a[0] = 3. On the Xeon Phi, neither a[0] = 1 or a[0] = 3 are executed. Full test case is: http://paste.ubuntu.com/25216421/

The device is a "Intel(R) Many Integrated Core Acceleration Card", the host OS is Ubuntu 16.04, and the driver version is:

$ cat /etc/OpenCL/vendors/intel64.icd
/opt/intel/opencl-1.2-4.4.0.117/lib64/libintelocl.so

Cheers,
Chris

Unfortunately, the Xeon Phi

Jeffrey_M_Intel1 — Tue, 01 Aug 2017 03:28:53 GMT

Unfortunately, the Xeon Phi drivers are deprecated. They are no longer maintained or supported by Intel. There are no more releases, and no bug fixes.

However, thank you for reporting this issue. This could help others on this forum.

topic Unfortunately, the Xeon Phi in OpenCL* for CPU

Invalid writes prevent valid writes

Unfortunately, the Xeon Phi