Computer Laboratory

Technical reports

Compilation and equivalence of imperative objects

Andrew D. Gordon, Paul D. Hankin, Søren B. Lassen

June 1997, 64 pages

Abstract

We adopt the untyped imperative object calculus of Abadi and Cardelli as a minimal setting in which to study problems of compilation and program equivalence that arise when compiling object-oriented languages. We present both a big-step and a small-step substitution-based operational semantics for the calculus. Our first two results are theorems asserting the equivalence of our substitution-based semantics with a closure-based semantics like that given by Abadi and Cardelli. Our third result is a direct proof of the correctness of compilation to a stack-based abstract machine via a small-step decompilation algorithm. Our fourth result is that contextual equivalence of objects coincides with a form of Mason and Talcott’s CIU equivalence; the latter provides a tractable means of establishing operational equivalences. Finally, we prove correct an algorithm, used in our prototype compiler, for statically resolving method offsets. This is the first study of correctness of an object-oriented abstract machine, and of operational equivalence for the imperative object calculus.

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BibTeX record

@TechReport{UCAM-CL-TR-429,
  author =	 {Gordon, Andrew D. and Hankin, Paul D. and Lassen, S{\o}ren
          	  B.},
  title = 	 {{Compilation and equivalence of imperative objects}},
  year = 	 1997,
  month = 	 jun,
  url = 	 {http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-429.ps.gz},
  institution =  {University of Cambridge, Computer Laboratory},
  number = 	 {UCAM-CL-TR-429}
}