Reply To: Internal Compiler Error (codegen):
Sorry, I forgot myself that channel3d is one of the cases that is not yet adapted to the new GPU-supporting style even in 1.7 (you can see a list of all verified examples in the Release Notes.
The reason for this is that the wall function used there is written in a particularly porting-unfriendly way. One of my colleagues is actually focused on remedying this right now, so keep a look out for the next release (should you be interested particularly in having wall function on GPUs in OpenLB).