A Formal C Memory Model Supporting Integer-Pointer Casts

Jeehoon KangChung-Kil Hur, William Mansky, Dmitri Garbuzov, Steve Zdancewic and Viktor Vafeiadis.
In Proceedings of the 36th annual ACM SIGPLAN conference on Programming Languages Design and Implementation (PLDI 2015).
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The ISO C standard does not specify the semantics of many valid programs that use non-portable idioms such as integer-pointer casts. Recent efforts at formal definitions and verified implementation of the C language inherit this feature. By adopting high-level abstract memory models, they validate common optimizations. On the other hand, this prevents reasoning about much low-level code relying on the behavior of common implementations, where formal verification has many applications.

We present the first formal memory model that allows many common optimizations and fully supports operations on the representation of pointers. All arithmetic operations are well-defined for pointers that have been cast to integers. Crucially, our model is also simple to understand and program with. All our results are fully formalized in Coq.