as-if - w3toppers.com

Loop with a zero execution time

Yes, under the as-if rule the compiler is only obligated to emulate the observable behavior of the code, so if you have a loop that does not have any observable behavior then it can be optimized away completely and therefore will effectively have zero execution time. Examples For example the following code: int main() { … Read more

What exactly is the “as-if” rule?

What is the “as-if” rule? The “as-if” rule basically defines what transformations an implementation is allowed to perform on a legal C++ program. In short, all transformations that do not affect a program’s “observable behavior” (see below for a precise definition) are allowed. The goal is to give implementations freedom to perform optimizations as long … Read more