You never have control of the wavefront size as this is something specified by the hardware design. All you can control is the local workgroup size, which is not the wavefront size. If you have a kernel that isn't compiling correctly, please post the kernel here.
Yes I meant group size.
Next, I take back all my statements ... I found out while preparing the test case for you there was a variable commented in my code !!!
So, everything seems fine comparing 10.12/HD5870 vs. 11.1/HD6970... sorry about my overexcitment, but I still hope AMD will consider continuous bug fixes rather than long durations between releases
Thank you for your prompt reply