关于引用调用

来源：互联网发布：怎样登陆阿里云服务器编辑：程序博客网时间：2024/06/18 09:10

从反汇编来看，就是传值还是传址。返回值与参数的传递都一样，引用就是传递/返回变量地址，传值就仅仅是传递或返回变量的值。

int &add(int &a, int b)

{
        return a+=b;
}

void test()
{
        int x = 11;
        int y = 4;
        int result = 0;
        result = add(x, y);
}

========================

080483f4 <_Z3addRii>:
80483f4:       55                      push   %ebp
80483f5:       89 e5                   mov    %esp,%ebp
80483f7:       8b 45 08                mov    0x8(%ebp),%eax
80483fa:       8b 00                   mov    (%eax),%eax
80483fc:       89 c2                   mov    %eax,%edx
80483fe:       03 55 0c                add    0xc(%ebp),%edx
8048401:       8b 45 08                mov    0x8(%ebp),%eax
8048404:       89 10                   mov    %edx,(%eax)
8048406:       8b 45 08                mov    0x8(%ebp),%eax
8048409:       5d                      pop    %ebp
804840a:       c3                      ret
804840b:       90                      nop

0804840c <_Z4testv>:
804840c:       55                      push   %ebp
804840d:       89 e5                   mov    %esp,%ebp
804840f:       83 ec 18                sub    $0x18,%esp
8048412:       c7 45 f4 0b 00 00 00    movl   $0xb,0xfffffff4(%ebp)
8048419:       c7 45 f8 04 00 00 00    movl   $0x4,0xfffffff8(%ebp)
8048420:       c7 45 fc 00 00 00 00    movl   $0x0,0xfffffffc(%ebp)
8048427:       8b 45 f8                mov    0xfffffff8(%ebp),%eax
804842a:       89 44 24 04             mov    %eax,0x4(%esp)
804842e:       8d 45 f4                lea    0xfffffff4(%ebp),%eax
8048431:       89 04 24                mov    %eax,(%esp)
8048434:       e8 bb ff ff ff          call   80483f4 <_Z3addRii>
8048439:       8b 00                   mov    (%eax),%eax
804843b:       89 45 fc                mov    %eax,0xfffffffc(%ebp)
804843e:       c9                      leave
804843f:       c3                      ret

=============================>

080483f4 <_Z3addii>:
80483f4:       55                      push   %ebp
80483f5:       89 e5                   mov    %esp,%ebp
80483f7:       8b 45 0c                mov    0xc(%ebp),%eax
80483fa:       01 45 08                add    %eax,0x8(%ebp)
80483fd:       8b 45 08                mov    0x8(%ebp),%eax
8048400:       5d                      pop    %ebp
8048401:       c3                      ret

08048402 <_Z4testv>:
8048402:       55                      push   %ebp
8048403:       89 e5                   mov    %esp,%ebp
8048405:       83 ec 18                sub    $0x18,%esp
8048408:       c7 45 f4 0b 00 00 00    movl   $0xb,0xfffffff4(%ebp)
804840f:       c7 45 f8 04 00 00 00    movl   $0x4,0xfffffff8(%ebp)
8048416:       c7 45 fc 00 00 00 00    movl   $0x0,0xfffffffc(%ebp)
804841d:       8b 45 f8                mov    0xfffffff8(%ebp),%eax
8048420:       89 44 24 04             mov    %eax,0x4(%esp)
8048424:       8b 45 f4                mov    0xfffffff4(%ebp),%eax
8048427:       89 04 24                mov    %eax,(%esp)
804842a:       e8 c5 ff ff ff          call   80483f4 <_Z3addii>
804842f:       89 45 fc                mov    %eax,0xfffffffc(%ebp)
8048432:       c9                      leave
8048433:       c3                      ret

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