The optimization is done in the JDK implementation (math shortcut) and then further taken advantage of by the JIT (inlining and constant folding). How is this

The optimization is done in the JDK implementation (math shortcut) and then further taken advantage of by the JIT (inlining and constant folding). How is this done? The implementation of a `Spliterator` that is used internally by `IntStream.rangeClosed` overrides the `estimateSize` method to return `((long) upTo) - from + last`, and the `characteristics` method to return, among others, the `Spliterator.SIZED` characteristic. That characteristic indicates that `estimateSize` can be trusted to be exact, and when present, `estimateSize` will be used as a shortcut in the implementation of `Stream.count`, which can be seen in `ReduceOps.makeRefCounting`.