Re: Decompiler, Expression Propagation, Intermediate Representation problems

> (1) Expression Propagation Problem


> c = a + b
> e = c + d
>
> they will be the following after expression propagation
>
> c = a + b
> e = a + b + d


Cristina Cifuentes [1] refers to this as the "forward substitution"
method. She restricts its application to temporary variables that are
defined then used only once. Cifuentes' thesis [2] has lots of
nitty-gritty detail.


Regards,
Jeremy




[1]


@article{cifuentes1995decompilation,
    title={Decompilation of binary programs},
    author={Cifuentes, C. and Gough, K.J.},
    journal={Software: Practice and Experience},
    volume={25},
    number={7},
    pages={811--829},
    year={1995},
    doi = "10.1002/spe.4380250706",
}




[2] C Cifuentes, Reverse Compilation Techniques, PhD thesis, Faculty of
Information Technology, Queensland University of Technology, July 1994.
ftp://ftp.it.uq.edu.au/pub/CSM/dcc/decompilation_thesis.ps.gz




>
> in a situation it's not safe:
>
> c = a + b
> e = c + d
> a = 1
> some_use(e) ; we must forbid the propagation of e = c+d since a = 1
> kills c = a + b so does e = c + d
>
> Now is the question: How to efficently/correctly implement this
> propagation? What's the analysis' name in theory?

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