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Attributed tree transformations with delayed and smart re-evaluation

  • Henk Alblas
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 371)

Abstract

Transformations of attributed program trees form an essential part of compiler optimizations. A tree transformation may invalidate attribute instances, not only in the restructured part of the tree but also elsewhere in the tree. To make the attribution of the tree correct again a re-evaluator has to be activated.

Criteria are formulated which allow a delay in calling the re-evaluator. These criteria allow a strategy of repeatedly applying alternate attribute evaluation and tree transformation phases. An attribute evaluation phase consists of a tree walk in which all attribute instances receive their correct values. A tree transformation phase consists of a tree walk in which as many tree transformations are performed as possible. The transformation phase is never interrupted to carry out a re-evaluation.

For re-evaluation purposes an incremental simple multi-pass evaluator is presented, which works optimally in the number of recomputations and in the number of visits to subtrees during each pass.

Keywords

Pass Number Attribute Evaluation Derivation Tree Evaluation Rule Attribute Instance 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1989

Authors and Affiliations

  • Henk Alblas
    • 1
  1. 1.Department of Computer ScienceUniversity of TwenteEnschedeThe Netherlands

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