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Use when code uses complex arithmetic expressions with modulo operations in conditional statements, especially involving multiple variables
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Based on SOC occupation classification
Use when printf statements output strings without trailing newlines
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Use when loop variables iterate over character values (e.g., ASCII codes) to represent different operations or choices
Use when code uses a loop to search for an input value in an array and then uses the found index for further computation
Use when code reads a fixed number of characters into an array and only accesses individual elements
| name | avoid-complex-modulo-conditions |
| description | Use when code uses complex arithmetic expressions with modulo operations in conditional statements, especially involving multiple variables |
A KLEE-coverage code transformation. Applying it rewrites C source so symbolic execution explores more of the program's behavior.
When code uses complex arithmetic expressions with modulo operations in conditional statements, especially involving multiple variables
Refactor to use floating-point arithmetic with rounding checks instead of integer arithmetic with modulo operations
Complex modulo expressions create non-linear constraints that are difficult for SMT solvers to reason about, while floating-point comparisons with rounding create simpler constraints that KLEE can explore more efficiently
Before:
#include <stdio.h>
typedef long long ll;
int main(void) {
ll n, i, j;
scanf("%lld", &n);
for(i = 1; i <= 3500; ++i) for(j = 1; j <= 3500; ++j) if(4 * i * j - i * n - j * n > 0 && !((n * i * j) % (4 * i * j - i * n - j * n))) {
printf("%lld %lld %lld", i, j, (n * i * j) / (4 * i * j - i * n - j * n));
return 0;
}
}
After:
#include <stdio.h>
#include <math.h>
int main(void){
double n,i,j,k,ans,ap;
scanf("%lf",&n);
ans = 4/n;
for (i=1;i<5000;i++)
{
for (j=1;j<5000;j++)
{
ap = ans - 1/i - 1/j;
if (ap >0)
{
ap = 1.0/ap;
ap = roundl(ap * 10000000) / 10000000;
if ((int)(ap) == ap)
{
printf("%d %d %d",(int)(i),(int)(j),(int)(ap));
return 0;
}
}
}
}
return 0;
}
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