9.5.3_e6.htm

来自「建立《编译原理网络课程》的目的不仅使学生掌握构造编译程序的原理和技术」· HTM 代码 · 共 42 行

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<img border="0" src="images/9_25_2.gif" align = left width="346" height="130">图2(b)的串联语句的规则有点微妙,由语句S=S1;S2注销的定值集合是什么?<p>
解析:首先,如果定值d被S2注销,那么它肯定到不了S的结束点,即肯定也被S注销;另外,如果d被S1注销,只要它不在S2中产生,它也不能到达S的结束点。所以我们认为: 
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<p><span style="FONT-WEIGHT: 900">kill[S]=kill[S2]∪(kill[S1]-gen[S2])</span> </td>
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