public RexNode visitCall(RexCall call) { List<RexNode> normalizedOperands = new ArrayList<RexNode>(); int diffCount = 0; for (RexNode operand : call.getOperands()) { operand.accept(this); final RexNode normalizedOperand = lookup(operand); normalizedOperands.add(normalizedOperand); if (normalizedOperand != operand) { ++diffCount; } } if (diffCount > 0) { call = call.clone(call.getType(), normalizedOperands); } return register(call); }