反汇编——结构体作为局部变量的传参和返回值的本质测试

来源：互联网发布：2016淘宝开店营业执照编辑：程序博客网时间：2024/06/05 16:21

不同编译器生成的结果不同，但本质都是通过寄存器或内存复制，本测试只是为了了解结构体在作为局部变量时的参数传递与返回的本质，实际使用中，最好定义为全局变量

结构体传参：

# include<stdio.h>struct st{char a;short b;int c;int d;int e;};void Function(st s){}int main(int argc, char* argv[]){st s;s.a = 1;s.b = 2;s.c = 3;s.d = 4;s.e = 5;Function(s);return 0;}反汇编：1.vs2017测试结果，使用寄存器传递地址Function(s);008A1740  sub         esp,10h  008A1743  mov         eax,esp  008A1745  mov         ecx,dword ptr [s]  008A1748  mov         dword ptr [eax],ecx  008A174A  mov         edx,dword ptr [ebp-10h]  008A174D  mov         dword ptr [eax+4],edx  008A1750  mov         ecx,dword ptr [ebp-0Ch]  008A1753  mov         dword ptr [eax+8],ecx  008A1756  mov         edx,dword ptr [ebp-8]  008A1759  mov         dword ptr [eax+0Ch],edx  008A175C  call        Function (08A10A5h)  008A1761  add         esp,10h  2.vc++6.0测试结果，直接使用rep stos指令，在内存内复制12:   void Function(st s)00401020   push        ebp00401021   mov         ebp,esp00401023   sub         esp,40h00401026   push        ebx00401027   push        esi00401028   push        edi00401029   lea         edi,[ebp-40h]0040102C   mov         ecx,10h00401031   mov         eax,0CCCCCCCCh00401036   rep stos    dword ptr [edi]00401038   pop         edi00401039   pop         esi0040103A   pop         ebx0040103B   mov         esp,ebp0040103D   pop         ebp0040103E   ret

结构体返回值：

# include<stdio.h>struct st{char a;short b;int c;int d;int e;};st Function(){st s;s.a = 1;s.b = 2;s.c = 3;s.d = 4;s.e = 5;return s;}int main(int argc, char* argv[]){st a = Function();return 0;}反汇编：vs2017测试结果，把Function函数的返回值的地址放在eaxst a = Function();0106171E  lea         eax,[ebp-104h]  //外层函数用来接收返回值的地址01061724  push        eax  01061725  call        Function (01061366h)  0106172A  add         esp,4  0106172D  mov         ecx,dword ptr [eax]  0106172F  mov         dword ptr [ebp-0ECh],ecx  01061735  mov         edx,dword ptr [eax+4]  01061738  mov         dword ptr [ebp-0E8h],edx  0106173E  mov         ecx,dword ptr [eax+8]  01061741  mov         dword ptr [ebp-0E4h],ecx  01061747  mov         edx,dword ptr [eax+0Ch]  0106174A  mov         dword ptr [ebp-0E0h],edx  01061750  mov         eax,dword ptr [ebp-0ECh]  01061756  mov         dword ptr [a],eax  01061759  mov         ecx,dword ptr [ebp-0E8h]  0106175F  mov         dword ptr [ebp-10h],ecx  01061762  mov         edx,dword ptr [ebp-0E4h]  01061768  mov         dword ptr [ebp-0Ch],edx  0106176B  mov         eax,dword ptr [ebp-0E0h]  01061771  mov         dword ptr [ebp-8],eax

vc++6.0测试结果，把Function函数的返回值的地址放在eax     st a = Function();0040D4D8   lea         eax,[ebp-30h]  //外层函数用来接收返回值的地址0040D4DB   push        eax0040D4DC   call        @ILT+20(Function) (00401019)0040D4E1   add         esp,40040D4E4   mov         ecx,dword ptr [eax]0040D4E6   mov         dword ptr [ebp-20h],ecx0040D4E9   mov         edx,dword ptr [eax+4]0040D4EC   mov         dword ptr [ebp-1Ch],edx0040D4EF   mov         ecx,dword ptr [eax+8]0040D4F2   mov         dword ptr [ebp-18h],ecx0040D4F5   mov         edx,dword ptr [eax+0Ch]0040D4F8   mov         dword ptr [ebp-14h],edx0040D4FB   mov         eax,dword ptr [ebp-20h]0040D4FE   mov         dword ptr [ebp-10h],eax0040D501   mov         ecx,dword ptr [ebp-1Ch]0040D504   mov         dword ptr [ebp-0Ch],ecx0040D507   mov         edx,dword ptr [ebp-18h]0040D50A   mov         dword ptr [ebp-8],edx0040D50D   mov         eax,dword ptr [ebp-14h]0040D510   mov         dword ptr [ebp-4],eax

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