Have a large input that causes a failure
(e.g., a core dump) but this input is to
Example: gcc takes input and crashes!
Question: What is the smallest input
Developed by Andreas Zeller et al. Institute for Software Technology Institute for Software Technology
double mult(double z[], int n) { WHICH PART OF BUG.C CAUSES
double mult(double z[], int n) { CRASH?????
void copy(double to[], from[], int count) {
void copy(double to[], from[], int count) {
int main (.) { . return copy(y,x,SIZE);}
int main (.) { . return copy(y,x,SIZE);} Institute for Software Technology Institute for Software Technology t(double z[],int n){int
The resulting substring is substantially
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Testing function that takes a program
and tests whether it produces a failure.
There are three different outcomes of such a testing function:
test(x)
The test produces the failure (FAIL, 8)
The test produces indeterminate results
Delta Debugging Institute for Software Technology Institute for Software Technology
Given:
An input c‘ ⊆ c is said to be the global
A testing function test(x) mapping an input
minimum iff test(c‘) = 8 and there exists
no c‘‘ with |c‘‘|≤|c‘| where
An input c with test(c) = 8.
Goal: Search for a smaller c‘ ⊂ c so that
An input c‘ ⊆ c is said to be the local
minimum iff test(c‘) = 8 and there exists no c‘‘⊂ c‘ where test(c‘‘) = 8. Institute for Software Technology Institute for Software Technology Minimizing delta debugging algorithm
Input: Let test and c be given such that test(c)=8 and test(∅)=9 hold.
Output: A c‘ ⊆ c such that test(c‘)=8
An input c‘⊆ c is n-minimal iff test(c‘) =
8 and there exists no c‘‘⊂ c‘ with |c‘| -
|c‘‘| ≤ n where test(c‘‘) = 8. Institute for Software Technology Institute for Software Technology
ddmin2(c,n) = ddmin2(∆ ,2) if ∃i∈{1,.,n}: test(∆ )=8 ddmin2(∇ ,max(n-1,2)) ddmin2(c,min(|c|,2n)) else if n<|c| 4. DONE otherwise test(c)=8 and n≤|c|Institute for Software Technology Institute for Software Technology
ddmin returns a 1-minimal result.
The complexity of ddmin is O(|c|2).
In the best case the complexity of ddmin
test(x) = 8 iff “2“ ⊆ x ⊆ cInstitute for Software Technology Institute for Software Technology
test(x) = 8 iff “18“ ⊆ x ⊆ c
Not only for inputs of type STRING Extensions of ddmin can be used to
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Have a large input that causes a failure
(e.g., a core dump) but this input is to
Example: gcc takes input and crashes!
Testing function that takes a program
and tests whether it produces a failure.
There are three different outcomes of such a testing function:
test(x)
ddmin2(c,n) =