return null;
int n = sources.size(); for (int i=0; i<n; i+=1) { Variable src = (Variable) sources.get(i); Operand op = src.simplify(); if (op instanceof StackVariable || op instanceof LocalVariable) { sources.set(i, op); } else { src.getAssignQuad().setDeadCode(false); } } return this;
	public Operand simplify() {		return null;	}