请问为什么有个警告

#include<reg52.h>
#include<intrins.h>
unsigned char t,num,temp;
unsigned char code table[]={0xfa,0xf5,0xaf,
0x5f,0xaa,0x55,0x00,0xff};

void main()
{
    num=0;
    EA=1;
    ET0=1;
    TMOD=0X00;
    TH0=(65536-50000)/256;
    TL0=(65536-50000)%256;
    TR0=1;
    temp=0xfe;
    P1=temp;
    while(1)
    {
        ;
    }
}

void time0() interrupt 1
{
    TH0=(65536-50000)/256;
    TL0=(65536-50000)%256;
    if(++t>=30)
    {
        t=0;
        num++;
        if(num>7)
            num=0;
        temp=_crol_(temp,1);
        P1=temp;
    }
}