On Tue, May 5, 2020 at 6:57 PM Pavel Machek pavel@denx.de wrote:
On Tue 2020-05-05 11:32:27, Sasha Levin wrote:
On Tue, May 05, 2020 at 05:05:37PM +0300, Andy Shevchenko wrote:
...
I'm a bit confused about this too. Maybe it's too early in the morning, so I wrote this little test program:
#include <stdio.h> #include <stdlib.h>
int main(int argc, char *argv[]) { int a = atoi(argv[1]); int b = atoi(argv[2]);
if (!a && !b) printf("A"); else printf("B"); if (!(a || b)) printf("A"); else printf("B"); printf("\n"); return 0;}
Andy, could you give an example of two values which will print something other than "AA" or "BB"?
The issue here is "sideffects". Does b have to be evaluated at all? There is no difference between
int a, b; if (a && b)and
if ((!!a) & (!!b)).
But there would be difference between
int a, b; if (a && b++)and if ((!!a) & (!!(b++)))
But:
&& and || behave same way w.r.t. side effects
in the patch we are talking about b has no important side effects
I have to admit that this seems like a luck and the real issue somewhere else. Definitely another test should be performed.
Thank you, Pavel, for pointing this out.