I saw this yesterday after rebuilding Mesa and running nexuiz.
Running again worked without error. 
This is the second time I've seen it, the first was a couple of weeks ago,
again after a rebuild of mesa this time with etqw.

I couldn't reproduce, but did get more output -

LLVM ERROR: Cannot select: target intrinsic %llvm.AMDIL.mad
Stack dump:
0.      Running pass 'Function Pass Manager' on module 'tgsi'.
1.      Running pass 'AMDGPU DAG->DAG Pattern Instruction Selection' on
function '@main'

I am using llvm 3.1 on HD4890.