The Program Structure Tree: Computing Control Regions in Linear Time

In this paper, we describe the program structure tree (PST), a hierarchical representation of program structure based on single entry single exit (SESE) regions of the control flow graph. We give a linear-time algorithm for finding SESE regions and for building the PST of arbitrary control flow graphs (including irreducible ones). Next, we establish a connection between SESE regions and control dependence equivalence classes, and show how to use the algorithm to find control regions in linear time. Finally, we discuss some applicationsof the PST. Many controlflow algorithms, such as construction of Static Single Assignment form, can be speeded up by applying the algorithms in a divide-andconquer style to each SESE region on its own. The PST is also used to speed up data flow analysis by exploiting `sparsity'. Experimental results from the Perfect Club and SPEC89 benchmarks confirm that the PST approach finds and exploits program structure.

• Type: Conference
• Year: 1994
• Where: PLDI
• Authors: Richard Johnson, David Pearson, Keshav Pingali
• Keywords: Control Flow Graphs, PLDI 1994, Program Structure, Programming Languages, Sese Region