简单C与汇编

C Swap

#include<stdio.h>
#include<stdlib.h>
void swap(long *a,long *b)
{
    long temp=*a;
    *a=*b;
    *b=temp;
}
int main(int argc,char *argv[])//Unix标准C语言main函数
//argc代表参数数量,argv是字符串数组，argv[0]是可执行文件的名字
{
    long a=atol(argv[1]);
    long b=atol(argv[2]);
    //long a=atol("2");
    //long b=atol("5");
    swap(&a,&b);
    printf("%ld %ld\n",a,b);
    printf("%s\n",argv[0]);
    return 0;
}
//执行命令 gcc -o first.out first.c
//得到first.out可执行文件
//执行./first.out 2 5 

汇编

执行命令：gcc -Og -S first.c 得到汇编结果first.s

        .file   "first.c"
        .text
        .globl  swap
        .type   swap, @function
swap:
.LFB38:
        .cfi_startproc
        movq    (%rdi), %rax
        movq    (%rsi), %rdx
        movq    %rdx, (%rdi)
        movq    %rax, (%rsi)
        ret
        .cfi_endproc
.LFE38:
        .size   swap, .-swap
        .section        .rodata.str1.1,"aMS",@progbits,1
.LC0:
        .string "%ld %ld\n"
        .text
        .globl  main
        .type   main, @function
main:
.LFB39:
        .cfi_startproc
        pushq   %rbx
        .cfi_def_cfa_offset 16
        .cfi_offset 3, -16
        subq    $32, %rsp
        .cfi_def_cfa_offset 48
        movq    %rsi, %rbx