private final void promoteSuccs(Instruction from, Instruction to) {
		if (succs == from)
			succs = to;
		else if (succs instanceof Instruction[]) {
			Instruction[] ss = (Instruction[]) succs;
			for (int i = 0; i < ss.length; i++)
				if (ss[i] == from)
					ss[i] = to;
		}
	}