if the same clmem object is passed into a kernel multiple times, the results are all zero. The opencl 1.2 specifications do not forbid passing the same clmem object into a kernel multiple times (section 5.7.2). This is entirely legal OpenCL
Apologies for dupe. I submitted prevoius bug report, then got email:
"This issue tracker is for bugs, not technical support. Please send a message to the mailing list for tech support."
... and angrily opened two bug reports instead.
But later on, I noticed the email was for a pyopencl bug report I'd submitted instead :-P https://github.com/pyopencl/pyopencl/issues/154#issuecomment-259449488
*** This bug has been marked as a duplicate of bug 98659 ***