return result;
return frame;
	private IsNullValueFrame replaceValues(IsNullValueFrame frame, ValueNumber replaceMe, ValueNumberFrame vnaFrame,		IsNullValue replacementValue) {		// The VNA frame may have more slots than the IsNullValueFrame		// if it was produced by an IF comparison (whose operand or operands		// are subsequently popped off the stack).		final int numSlots = Math.min(frame.getNumSlots(), vnaFrame.getNumSlots());		final IsNullValueFrame result = createFact();		result.copyFrom(frame);		for (int i = 0; i < numSlots; ++i) {			if (vnaFrame.getValue(i).equals(replaceMe))				result.setValue(i, replacementValue);		}		return result;	}