Verifying local transformations on relaxed memory models

  • Authors:

  • Sebastian Burckhardt;Madanlal Musuvathi;Vasu Singh

  • Affiliations:

  • Microsoft Research;Microsoft Research;EPFL, Switzerland

  • Venue:
  • CC'10/ETAPS'10 Proceedings of the 19th joint European conference on Theory and Practice of Software, international conference on Compiler Construction
  • Year:
  • 2010

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Abstract

The problem of locally transforming or translating programs without altering their semantics is central to the construction of correct compilers. For concurrent shared-memory programs this task is challenging because (1) concurrent threads can observe transformations that would be undetectable in a sequential program, and (2) contemporary multiprocessors commonly use relaxed memory models that complicate the reasoning. In this paper, we present a novel proof methodology for verifying that a local program transformation is sound with respect to a specific hardware memory model, in the sense that it is not observable in any context. The methodology is based on a structural induction and relies on a novel compositional denotational semantics for relaxed memory models that formalizes (1) the behaviors of program fragments as a set of traces, and (2) the effect of memory model relaxations as local trace rewrite operations. To apply this methodology in practice, we implemented a semi- automated tool called Traver and used it to verify/falsify several compiler transformations for a number of different hardware memory models.