it seems that this is a bug in LLBMC, where a certain construct is not yet supported.
The "add support" part in the error message is more directed to us, not you.
We will fix this in a maintenance release that will be available very soon.
To make sure that your program is also covered by our fix, could you please send us
your C code and/or the bitcode file that resulted in the error message?
Thanks for reporting the bug!
-- Stephan & Carsten