海湾合作委员会:与-O0的奇怪错误,没有没有

Question

我想在没有优化的情况下编译我的C代码,但是当我在编译命令中添加-O0选项时,我得到了许多"多个定义"错误,我甚至没有写过函数!我想有一些显而易见的东西我在这里不见了,但作为一个菜鸟,我只是无法弄清楚是什么......

这是我的代码:

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <wiringPi.h>
#include <time.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <semaphore.h>
#include <unistd.h>
#include <sched.h>
#include <time.h>

#define N       1800

unsigned long int tsec, tnsec;

int main(void)
{
        int err, i;
        printf("started\n");

        struct timespec tps, tpe, req, rem;

        req.tv_nsec = 400000;
        req.tv_sec = 0;

        struct sched_param param;
        param.sched_priority = 99;
        err = sched_setscheduler(getpid(), SCHED_FIFO, &param);
        if (err != 0)
                printf("sched_setscheduler error");
        err = sched_getparam(getpid(), &param);
        if (err != 0)
                printf("sched_getparam error");
        printf("priority = %i\n", param.sched_priority);

        int policy = sched_getscheduler(getpid());
        printf("policy = %i\n", policy);


        sleep(1);

        clock_gettime(CLOCK_REALTIME, &tps);

        #include "noppynop2.c"
        #include "noppynop2.c"
        #include "noppynop2.c"
        #include "noppynop2.c"
        #include "noppynop2.c"
        #include "noppynop2.c"


        clock_gettime(CLOCK_REALTIME, &tpe);
        tnsec = tpe.tv_nsec - tps.tv_nsec;
        tsec = tpe.tv_sec - tps.tv_sec;
        printf("time = %lu sec %lu nsec\n", tsec, tnsec);


        printf("finished\n");

        return 0;
}

总而言之,这是在实时内核的Linux上造成延迟的暴力尝试."noppynop2.c"包含500次asm("nop").我不认为这是问题,但这是背景.代码主要只是一个测试,我想摆脱所有的优化,因为目前编译器倾向于删除(显然)不可预测的数量的"nops",这与我正在尝试做的完全相反...

当我在没有-O0选项的情况下编译时,一切都很顺利:

pi@raspberrypi ~/Desktop/Projects/test_timemeasure_sched $ gcc -Wall -o test_time_measure_sched main.c -lwiringPi -lpthread -lrt
main.c: In function ‘main’:
main.c:22:33: warning: unused variable ‘rem’ [-Wunused-variable]
main.c:22:28: warning: variable ‘req’ set but not used [-Wunused-but-set-variable]
main.c:19:11: warning: unused variable ‘i’ [-Wunused-variable]

但是当我在这里添加-O0时,我得到的是:

pi@raspberrypi ~/Desktop/Projects/test_timemeasure_sched $ gcc -Wall -o -O0 test_time_measure_sched main.c -lwiringPi -lpthread -lrt
main.c: In function ‘main’:
main.c:22:33: warning: unused variable ‘rem’ [-Wunused-variable]
main.c:22:28: warning: variable ‘req’ set but not used [-Wunused-but-set-variable]
main.c:19:11: warning: unused variable ‘i’ [-Wunused-variable]
test_time_measure_sched: In function `_fini':
:(.fini+0x0): multiple definition of `_fini'
/usr/lib/gcc/arm-linux-gnueabihf/4.6/../../../arm-linux-gnueabihf/crti.o:(.fini+0x0): first defined here
test_time_measure_sched: In function `__data_start':
:(.data+0x0): multiple definition of `__data_start'
/usr/lib/gcc/arm-linux-gnueabihf/4.6/../../../arm-linux-gnueabihf/crt1.o:(.data+0x0): first defined here
test_time_measure_sched: In function `__data_start':
:(.data+0x4): multiple definition of `__dso_handle'
/usr/lib/gcc/arm-linux-gnueabihf/4.6/crtbegin.o:(.data+0x0): first defined here
test_time_measure_sched:(.rodata+0x0): multiple definition of `_IO_stdin_used'
/usr/lib/gcc/arm-linux-gnueabihf/4.6/../../../arm-linux-gnueabihf/crt1.o:(.rodata.cst4+0x0): first defined here
test_time_measure_sched: In function `_start':
:(.text+0x0): multiple definition of `_start'
/usr/lib/gcc/arm-linux-gnueabihf/4.6/../../../arm-linux-gnueabihf/crt1.o:(.text+0x0): first defined here
test_time_measure_sched: In function `_init':
:(.init+0x0): multiple definition of `_init'
/usr/lib/gcc/arm-linux-gnueabihf/4.6/../../../arm-linux-gnueabihf/crti.o:(.init+0x0): first defined here
/tmp/cc5At86c.o: In function `main':
main.c:(.text+0x0): multiple definition of `main'
test_time_measure_sched::(.text+0xac): first defined here
collect2: ld returned 1 exit status

我该怎么做才能摆脱这些错误？

Thanx提前为您提供帮助.

最好的祝福.

埃里克

Answer 1

gcc命令应该是

gcc -Wall -O0 -o test_time_measure_sched main.c -lwiringPi -lpthread -lrt

代替

gcc -Wall -o -O0 test_time_measure_sched main.c -lwiringPi -lpthread -lrt

使用第二个命令,旧二进制test_time_measure_sched文件被gcc视为输入文件.您获得的其他错误都是链接器错误,这表明gcc尝试将旧二进制文件链接到新代码.