This paper presents a structuring algorithm for arbitrary reducible, unstructured graphs. Graphs are structured into semantically equivalent graphs, without the need of code replication or introduction of new variables. The algorithm makes use of structures such as, if..then..elses, while, repeat and loop loops, and case statements. Gotos are only used when the graph cannot be structured with any of the above constructs. This algorithm is adequate for the analysis needed in the decompilation of programs, given that a binary program does not contain information as to the language and compiler used to compile the original source program. And given that unstructuredness is introduced by the use of gotos (still widely available in today's compilers) and optimizations produced by the compiler, we have to assume an unstructured graph for our decompilation analysis. This algorithm has been implemented as part of the dcc decompiler, currently under development at the Queensland University of ...

A proposed methodology for decompilation of binary programs is presented, along with a description of a particular implementation of this methodology, dcc. dcc is a decompiler for the Intel 80x86 architecture, which takes as input a binary program from a DOS environment and produces C programs as output. The decompiler has been divided into three separate modules which resemble the structure of the compiler. The front-end module is machine dependent and performs the loading and parsing of the program, as well as the generation of an intermediate representation. The universal decompiling machine module is machine and language independent, and performs all the flow analysis of the program. Finally, the back-end module is language dependent and deals with the details of the target high level language. Even though the problem of decompilation is insoluble in general, a partial solution can be found, which gives information about the binary program. This paper describes some of the results ...