m1-benchmark.c

#include <time.h>
#include <stdio.h>

int main() {
    int i;
    int j;
    int k;
    int a;
    int b;
    const int n = 100000000;

    clock_t start;
    clock_t end;

    printf("============= warm up ==============\n");
    i = 0;
    a = 0;
    start = clock();
    while (i < n) {
        if (i % 3 == 0) {
            a += i*2;
        } else {
            a -= i;
        }
        i++;
    } 
    end = clock();
    printf("a: %d\n", a);  // make sure a is not optimized away
    printf("t1: %ld\n", end - start);


    j = 0;
    b = 0;
    start = clock();
    while (j < n) {
        if (j % 7 == 0) {
            b += j*6;
        } else {
            b -= j;
        }
        j++;
    } 
    end = clock();
    printf("b: %d\n", b);
    printf("t2: %ld\n", end - start);


    i = 0;
    j = 0;
    a = 0;
    b = 0;
    k = 0;
    start = clock();
    while (k < n) {
        if (i % 3 == 0) {
            a += i*2;
        } else {
            a -= i;
        }
        i++;
        if (j % 7 == 0) {
            b += j*6;
        } else {
            b -= j;
        }
        j++;
        k++;
    }

    end = clock();
    printf("a: %d\n", a);
    printf("b: %d\n", b);
    printf("t3: %ld\n", end - start);

    printf("============= benchmark ==============\n");
    i = 0;
    a = 0;
    start = clock();
    while (i < n) {
        if (i % 3 == 0) {
            a += i*2;
        } else {
            a -= i;
        }
        i++;
    } 
    end = clock();
    printf("a: %d\n", a);  // make sure a is not optimized away
    printf("t1: %ld\n", end - start);


    j = 0;
    b = 0;
    start = clock();
    while (j < n) {
        if (j % 7 == 0) {
            b += j*6;
        } else {
            b -= j;
        }
        j++;
    } 
    end = clock();
    printf("b: %d\n", b);
    printf("t2: %ld\n", end - start);


    i = 0;
    j = 0;
    a = 0;
    b = 0;
    k = 0;
    start = clock();
    while (k < n) {
        if (i % 3 == 0) {
            a += i*2;
        } else {
            a -= i;
        }
        i++;
        if (j % 7 == 0) {
            b += j*6;
        } else {
            b -= j;
        }
        j++;
        k++;
    }

    end = clock();
    printf("a: %d\n", a);
    printf("b: %d\n", b);
    printf("t3: %ld\n", end - start);

    return 0;
}