C程序单元级依赖性分析

Analysis of Dependences among C Program Units

程序依赖性分析是软件分析的一个基本内容 ,目前的相关工作大多集中在语句级的分析方面。人们同样需要单元级的依赖信息来考察单元间的信息流向及整个程序的构架。本文针对C程序中函数间的调用依赖、参数传递依赖、全局数据依赖以及文件间的包含依赖和外部变量定义依赖进行了分析 ,并提出单元依赖图表达这些关系。基于此图 ,本文采用基于信息论的方法度量了单元间的耦合性。单元依赖图中保留的函数调用间的互斥关系提高了度量的准确性。相关的分析思想和技术适用于分析使用其它高级程序设计语言编写的软件。

The focus of software dependence analysis is on the dependences between statements, however the dependence information among program units is useful to improve software comprehension. This paper analyses the dependences among C program units caused by function call, parameter transformation, using of nonlocal data and the dependences among files caused by the use of include and extern. We introduce Dependence-Graph among Program Units(DGPU) to express these relations, based on which a measurement method for coupling is presented. The exclusion among function calls expressed by DGPU makes the measurement more accurate. The main idea and technology presented in this paper can also be utilized to analyze programs written in other high level programming languages.