Signed overflow optimization hazards in the kernel [LWN.net]

Signed overflow optimization hazards in the kernel

Posted Aug 17, 2012 19:09 UTC (Fri) by iabervon (subscriber, #722)
In reply to: Signed overflow optimization hazards in the kernel by cmccabe
Parent article: Signed overflow optimization hazards in the kernel

int find(char *s, char c, int lim)
{
  for (int i = 0; i != lim && s[i]; i++)
    if (s[i] == c)
      return i;
  return -1;
}

int main()
{
  find("foo", 'o', 1);
  find("foo", 'o', -1);
}

If the compiler inlines the second call, it can drop the "i != lim" test by assuming that overflow is impossible.