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[Frama-c-discuss] Value analysis and termination

  • Subject: [Frama-c-discuss] Value analysis and termination
  • From: hollas at informatik.htw-dresden.de (Boris Hollas)
  • Date: Mon, 11 Oct 2010 20:50:00 +0200
Hi,

I wanted to use the following example to explain that abstract
interpretation can determine that i \in {-4,4} at the end of main().
However, the value analysis shows i \in {-4,0,4} at this point. But i ==
0 is not possible since !(i % 2 == 0) is necessary for the loop to
terminate.  Why doesn't the value analysis detect this?


int foo();

int main() {
	int i;
	
	i = foo();
	while(i % 2 == 0) {
		i = i/2;
	}
	i = 4 * (i % 2);
	return 0;
}
	

-- 
Regards,
Boris