Abstract

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 ...

Citations

801	Depth-first search and linear graph algorithms - Tarjan - 1972
78	Control flow analysis - Allen - 1970
73	Testing flow graph reducibility - Tarjan - 1974
59	Global Common Subexpression Elimination - Cocke - 1970
45	An algorithm for structuring flowgraphs - Baker - 1977
32	Eliminating go to’s while preserving program structure - Ramshaw - 1988
23	A basis for program optimization - Allen - 1971
19	Structural analysis: a new approach to flow analysis in optimizing compilers - Sharir - 1980
13	Analysis of structured programs - Kosaraju - 1974
7	A study of decompiling machine languages into high-Level machine independent languages - Housel - 1973
2	Analysis of Computer Programs. 52 Vanderbilt Avenue - Hecht - 1977
2	J.Cocke, "Graph theoretic constructs for program control flow analysis - Allen - 1972
2	J.Ullman, "A simple algorithm for global data flow analysis problems - Hecht - 1975
1	G.Chen, "Restructuring pascal programs containing goto statements - Williams - 1985