Combining Slicing and Constraint Solving for Better Debugging: The CONBAS Approach

Algorithm 1

RELEVANTSLICE (ET, Π, 𝑥, 𝑛).

Require: An execution trace ET=⟨𝑠₁,…,𝑠_𝑚⟩, a variable of interest 𝑥, and a certain line

     number of the execution trace 𝑛.

Ensure: A relevant slice.

  (1)  Compute the execution trace ETG using the dependence relations →_𝐶, →_𝐷, and →_𝑃.

  (2)  Mark the node 𝑠_𝑘 in the ETG, where 𝑥∈DEF(𝑠_𝑘) and there is no other

    statement 𝑠_𝑖, 𝑘<𝑖≤𝑛, 𝑥∈DEF(𝑠_𝑖) in the ETG.

  (3)  Mark all test nodes between 𝑠_𝑘 and 𝑠_𝑛, which evaluate to the boolean value 𝐵 and where

     𝑥∈PR(𝑠_𝑘,𝐵).

  (4)  Traverse the ETG from the marked nodes in the reverse direction of the arcs until no

     new nodes can be marked.

  (5)  Let 𝑆 be the set of all marked nodes.

  (6)  Return the set {𝑠_𝑖∣𝑠_𝑖∈𝑆} as result.