Testing flow graph reducibility

  • Authors:
  • Robert Tarjan

  • Affiliations:
  • -

  • Venue:
  • STOC '73 Proceedings of the fifth annual ACM symposium on Theory of computing
  • Year:
  • 1973

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Abstract

Many problems in program optimization have been solved by applying a technique called interval analysis to the flow graph of the program. A flow graph which is susceptible to this type of analysis is called reducible. This paper describes an algorithm for testing whether a flow graph is reducible. The algorithm uses depth-first search to reveal the structure of the flow graph and a good method for computing disjoint set unions to determine reducibility from the search information. When the algorithm is implemented on a random access computer, it requires O(E log* E) time to analyze a graph with E edges, where log* x &equil; min{i/logix≤1}. The time bound compares favorably with the O(E log E) bound of a previously known algorithm.