Because it will force only to execute one of the conditional branch. <a href="https:&#x2F;&#x2F;github.com&#x2F;wkoszek&#x2F;cpu60&#x2F;blob&#x2F;master&#x2F;cpu60.c" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;wkoszek&#x2F;cpu60&#x2F;blob&#x2F;master&#x2F;cpu60.c</a> might execute several. (It may be on purpose though.)