Timing int vs long long

bitshifts.cpp

#include <chrono>
#include <iostream>
using namespace std;
using namespace chrono;
using ll = long long;
using ull = unsigned long long;

auto now(){ return high_resolution_clock::now(); }
int main(){
	auto t1 = now();

	{
		int k = 15;
		int N = 30;
		int mask = (1 << k) - 1;
		while (!(mask & 1 << N)) {
			int lo = mask & ~(mask - 1);
			int lz = (mask + lo) & ~mask;
			mask |= lz;
			mask &= ~(lz - 1);
			mask |= (lz / lo / 2) - 1;
		}
	}

	auto t2 = now();
	{
		ll k = 15;
		ll N = 30;
		ll mask = (1ll << k) - 1ll;
		while (!(mask & 1ll << N)) {
			ll lo = mask & ~(mask - 1ll);
			ll lz = (mask + lo) & ~mask;
			mask |= lz;
			mask &= ~(lz - 1ll);
			mask |= (lz / lo / 2ll) - 1ll;
		}
	}
	auto t3 = now();

	{
		unsigned k = 15;
		unsigned N = 30;
		unsigned mask = (1u << k) - 1u;
		while (!(mask & 1u << N)) {
			unsigned lo = mask & ~(mask - 1u);
			unsigned lz = (mask + lo) & ~mask;
			mask |= lz;
			mask &= ~(lz - 1u);
			mask |= (lz / lo / 2u) - 1u;
		}
	}

	auto t4 = now();
	{
		ull k = 15;
		ull N = 30;
		ull mask = (1ull << k) - 1ull;
		while (!(mask & 1ull << N)) {
			ull lo = mask & ~(mask - 1ull);
			ull lz = (mask + lo) & ~mask;
			mask |= lz;
			mask &= ~(lz - 1ull);
			mask |= (lz / lo / 2ull) - 1ull;
		}
	}
	auto t5 = now();

	cout << (t2-t1).count() << "\t(int)" << endl;
	cout << (t3-t2).count() << "\t(long long)" << endl;
	cout << (t4-t3).count() << "\t(unsigned)" << endl;
	cout << (t5-t4).count() << "\t(unsigned long long)" << endl;

}