After Chandler's latest changes, having TTI seems to have become obligatory
(otherwise you can get a crash in SelectionDAG.cpp:3392, in the second of the
following two lines:
  const TargetTransformInfo *TTI = DAG.getTargetTransformInfo();
  if (TTI->getIntImmCost(Val, VT.getTypeForEVT(*DAG.getContext())) < 2)
).