• Piotr Grochowski (37/37) Apr 07 2023 This glitching called Division constant leak is more tricky to

Piotr Grochowski <piotrunio-2004 wp.pl> writes:

This glitching called Division constant leak is more tricky to 
reproduce than Bad multiplication, Infinite compiling, and 
Structure initalization corruption. Division constant leak is a 
glitching that only occurs with *optimizations* (-o).

```d
#include <vector>
#include <iostream>
int main(int argc,char**argv){
  size_t _0=argc>>15;
  long o=100;
  std::vector<long> v(&o,&o+1);
  if(v[_0/3]==v[0]){o=v[0];}
  std::cout<<o;
}
```

It results in the constant -1431655765 (0xAAAAAAAB) being output, 
being the division constant being leaked. With other denominators 
it could leak another constant, such as with the denominator of 
5, it outputs -858993459 (0xCCCCCCCD).

The Division constant leak has also been observed to cause 
crashes when the division constant leaks to the array index:

```d
#include <vector>
#include <iostream>
int main(int argc,char**argv){
  std::vector<long> u;
  size_t _0=argc>>15;
  long o=100;
  std::vector<long> v(&o,&o+1);
  size_t _5 = _0+5;
  if(v[_0/3]==v[_5/5-1]){
   u.push_back(0);
   o=v[_5/5-1];
  }
  std::cout<<o;
}
```