使用demo

#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#define ARRAY_LEN 30000
static struct timeval tm1;
static inline void start()
{
    gettimeofday(&tm1, NULL);
}

static inline void stop()
{
    struct timeval tm2;
    gettimeofday(&tm2, NULL);
    unsigned long long t = 1000 * (tm2.tv_sec - tm1.tv_sec) +\
                           (tm2.tv_usec - tm1.tv_usec) / 1000;
    printf("%llu ms\n", t);
}

void bubble_sort (int *a, int n)
{
    int i, t, s = 1;
    while (s)
    {
        s = 0;
        for (i = 1; i < n; i++)
        {
            if (a[i] < a[i - 1])
                {
                    t = a[i];
                    a[i] = a[i - 1];
                    a[i - 1] = t;
                    s = 1;
                }
        }
    }
}

void sort_array()
{
    printf("Bubble sorting array of %d elements\n", ARRAY_LEN);
    int data[ARRAY_LEN], i;
    for(i=0; i<ARRAY_LEN; ++i)
   {
        data[i] = rand();
    }
    bubble_sort(data, ARRAY_LEN);
}

int main()
{
    start();
    sort_array();
    stop();
    return 0;
}

mkdir pgo-profile
gcc -O3 -fcfgo-profile-generate=./pgo-frofile bubble-srot.c -o bubble-sort.o
./bubble-sort.o

mkdir cspgo-profile
gcc -O3 -fcfgo-profile-use=./pgo-frofile -fcfgo-csprofile-generate=./cspgo-profile bubble-srot.c -o bubble-sort.o
./bubble-sort.o

mkdir cspgo-profile
gcc -O3 -fcfgo-profile-use=./pgo-frofile -fcfgo-csprofile-use=./cspgo-profile bubble-srot.c -o bubble-sort.o
./bubble-sort.o