关键词: C程序重构,程序变换,程序理解,代码提取,循环分析,LLVM

Abstract: As program complexity increases,code refactoring plays an important role in improving quality and perfor-mance of software,and is also essential for improving the maintainability and extensibility of programs.Current code extraction approach for C code in Eclipse,can only deal with some simple code,and cannot refactor the code automatically.In this paper,we proposed a code extraction approach for C code,CCodeExtractor.It can extract the C code fragments that meet the specified conditions into new functions,and replace the fragments with these new functions calls automatically.The refactored code has the same program semantics as the original code.In order to verify the validity of CCodeExtractor,we implemented it in LLVM to extract some for statements in C programs into new functions since loop ana-lysis and optimization has been widely explored in recent years.Our experiments evaluated CCodeExtractor using six actual applications of different size,and compared the outcomes of the original and transformed programs.Experimental results show that CCodeExtractor can provide correct source-level transformation for programs of different size.

Key words: C program refactoring,Program transformation,Program comprehension,Code extraction,Loop analysis,LLVM