branch.cpp

branch.cpp

#include <stdio.h>
#include <time.h>
#include <stdint.h>
#include <stdlib.h>
#include <chrono>
#include <thread>

int64_t clock_realtime()
{
	return std::chrono::duration_cast<std::chrono::nanoseconds>(
			std::chrono::system_clock::now().time_since_epoch()).count();
}

void isleep(unsigned long millisecond)
{
	std::this_thread::sleep_for(std::chrono::milliseconds(millisecond));
}

#define TIMES 1000
#define N 100000

int min = 3333, max = 6666;

void benchmark1()
{
	isleep(1000);
	srand(1);
	int64_t ts = clock_realtime();
	int s = 0;
	for (int k = 0; k < TIMES; k++) {
		for (int j = 0; j < N; j++) {
			int x = rand() % 10000;
			if (x >= min && x <= max) {
				s += x;
			}
			else {
				s -= x;
			}
		}
	}
	ts = clock_realtime() - ts;
	printf("bench 1: time=%d s=%d\n", (int)ts, s);
}


void benchmark2()
{
	isleep(1000);
	srand(1);
	int64_t ts = clock_realtime();
	int s = 0;
	for (int k = 0; k < TIMES; k++) {
		for (int j = 0; j < N; j++) {
			int x = rand() % 10000;
			if (((x - min) | (max - x)) >= 0) {
				s += x;
			}
			else {
				s -= x;
			}
		}
	}
	ts = clock_realtime() - ts;
	printf("bench 2: time=%d s=%d\n", (int)ts, s);
}

int main(void)
{
	benchmark1();
	benchmark2();
	return 0;
}

/*
bench 1: time=2063884 s=-1103064781
bench 2: time=1316591 s=-1103064781
*/