How do I make an infinite empty loop that won't be optimized away?

Question

The C11 standard appears to imply that iteration statements with constant controlling expressions should not be optimized out. I\'m taking my advice from this answer, which

Answer 1

The loop has no side-effects, and so can be optimized out. The loop is effectively an infinite number of iterations of zero units of work. This is undefined in mathematics and in logic and the standard doesn't say whether an implementation is permitted to complete an infinite number of things if each thing can be done in zero time. Clang's interpretation is perfectly reasonable in treating infinity times zero as zero rather than infinity. The standard doesn't say whether or not an infinite loop can end if all the work in the loops is in fact completed.

The compiler is permitted to optimize out anything that's not observable behavior as defined in the standard. That includes execution time. It is not required to preserve the fact that the loop, if not optimized, would take an infinite amount of time. It is permitted to change that to a much shorter run time -- in fact, that the point of most optimizations. Your loop was optimized.

Even if clang translated the code naively, you could imagine an optimizing CPU that can complete each iteration in half the time the previous iteration took. That would literally complete the infinite loop in a finite amount of time. Does such an optimizing CPU violate the standard? It seems quite absurd to say that an optimizing CPU would violate the standard if it's too good at optimizing. The same is true of a compiler.