[Bug string/26091] strcpy cost more time in glibc-2.31

[guojinhui at huawei dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=26091

--- Comment #2 from JinhuiGuo <guojinhui at huawei dot com> ---
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>
#include <string.h>

int s = 10;
int unaligned = 0;

void init_str(char *str)
{
        static char *demo =
                "The quick brown fox jumps over the lazy dog.";
        int l = strlen(demo);
        int i;
        for (i = 0; i < s; i++) {
                str[i] = demo[i % l];
        }

        str[s] = 0;
}

int main(void)
{
        int i;
        struct timespec tv;
        struct timespec tv1;

        char *src2 = (char *)malloc(s + 1);
        char *src = (char *)malloc(s + 1 + unaligned);
        init_str(src2);
        src2 += unaligned;

        clock_gettime(CLOCK_MONOTONIC, &tv);

        for (i = 0; i < 1100000; i += 10) {
                (void) strcpy(src, src2);
                (void) strcpy(src, src2);
                (void) strcpy(src, src2);
                (void) strcpy(src, src2);
                (void) strcpy(src, src2);
                (void) strcpy(src, src2);
                (void) strcpy(src, src2);
                (void) strcpy(src, src2);
                (void) strcpy(src, src2);
                (void) strcpy(src, src2);
        }

        clock_gettime(CLOCK_MONOTONIC, &tv1);
        long long  tmp = ((long long)tv1.tv_sec * 1000000000LL) - ((long
long)tv.tv_sec * 1000000000LL)  + ((long long)tv1.tv_nsec ) - ((long
long)tv.tv_nsec);
        printf("cost: %f ns\n", ((double)tmp) / i);

        src2 -= unaligned;
        free(src);
        free(src2);

        return 0;
}

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