A Comparison of the Worst-Case Complexities of Two Algorithms for the Reaching Definitions Problem

Article type: Research Article

Authors: Czech, Zbigniew

Affiliations: Silesian Technical University, Gliwice

Abstract: An algorithm to solve the “reaching definitions” problem on reducible flow graphs is presented. It is based on the concept of a region of a flow graph, and has the worst-case time bound of O(n2) bit-vector operations. The algorithm is compared for time complexity with the well-known round-robin version of the iterative algorithm. The comparison shows that for every flow graph of n>2 nodes the region analysis algorithm for the “reaching definitions” problem requires in the worst case fewer bit-vector operations than the round-robin version of the iterative algorithm for the same problem.

Keywords: global program optimization, flow graph, reducibility, region analysis, depth-first spanning tree, data flow analysis, reaching definitions, time complexity

DOI: 10.3233/FI-1984-7104

Journal: Fundamenta Informaticae, vol. 7, no. 1, pp. 57-76, 1984