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Use when code uses modulo operator (%) to extract digits or parts of a number
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| name | avoid-modulo-operations |
| description | Use when code uses modulo operator (%) to extract digits or parts of a number |
A KLEE-coverage code transformation. Applying it rewrites C source so symbolic execution explores more of the program's behavior.
When code uses modulo operator (%) to extract digits or parts of a number
Replace modulo operations with equivalent arithmetic using subtraction and multiplication (e.g., replace 'a%100' with 'a-100*(a/100)')
Modulo operations create more complex symbolic expressions in KLEE, making constraint solving harder and potentially limiting path exploration, while arithmetic operations with multiplication and subtraction produce simpler constraints
Before:
#include<stdio.h>
int main(){
int a;scanf("%d",&a);
int L=a/100;
int R=a%100;
if(1<=L&&L<=12){
if(1<=R&&R<=12)printf("AMBIGUOUS\n");
else printf("MMYY\n");
}else{
if(1<=R&&R<=12)printf("YYMM\n");
else printf("NA\n");
}
}
After:
#include<stdio.h>
int main()
{
int a, b, c, d, e;
scanf("%d", &e);
a=e/100;
b=e-100*a;
if(a>=1&&a<=12)
{
if(b>=1&&b<=12)
printf("AMBIGUOUS");
else
printf("MMYY");
}
else
{
if(b>=1&&b<=12)
printf("YYMM");
else
printf("NA");
}
}
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