Both of your examples are optimized by the compiler (gcc 16.1 -O3).

In the first case, the compiler removes the first if/return

In the second case, if you don't have the first if/return the compiler will add it. That's because it will actually convert your loop into a do/while, with the test in the end, because it is more efficient. But it has to handle the count == 0 special case first, so it will do that early return even if it is not explicitly there.

That's the kind of optimization modern compilers are good at.