Makes sense. When a temporary is the result of a simple expression with no side effects that is expected to evaluate to the same value each time, the temporary can be taken back. An obvious example of this is constant folding. We set a temporary t27 to 42. Well, that can just be 42 everywhere, so we don't need the temporary. The trust "evaluate to same value each time" is based on assumptions, which, if they are wrong, things are screwed.