一段C定義的局部變數的彙編代碼

vc6.0

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--- D:/simon/try/wqer/1.c  --------------------------------------------------------------------------------------------------------
1:
2:
3:
4:
5:
6:
7:    int i = 0x10;
8:    int arr_i[5] = {0x11,0x12,0x13,0x14,0x15};
9:
10:   int main(    )
11:   {
0040D360   push        ebp
0040D361   mov         ebp,esp
0040D363   sub         esp,7Ch
0040D366   push        ebx
0040D367   push        esi
0040D368   push        edi
0040D369   lea         edi,[ebp-7Ch]
0040D36C   mov         ecx,1Fh
0040D371   mov         eax,0CCCCCCCCh
0040D376   rep stos    dword ptr [edi]
12:       //..
13:       int b = arr_i[3];
0040D378   mov         eax,[_arr_i+0Ch (00424a40)]
0040D37D   mov         dword ptr [ebp-4],eax
14:
15:       int l_1 = 0x1;
0040D380   mov         dword ptr [ebp-8],1
16:       int l_2 = 0x2;
0040D387   mov         dword ptr [ebp-0Ch],2
17:       int l_3 = 0x3;
0040D38E   mov         dword ptr [ebp-10h],3
18:
19:       int l_arr_i[5] = {0x21,0x22,0x23,0x24,0x25};
0040D395   mov         dword ptr [ebp-24h],21h
0040D39C   mov         dword ptr [ebp-20h],22h
0040D3A3   mov         dword ptr [ebp-1Ch],23h
0040D3AA   mov         dword ptr [ebp-18h],24h
0040D3B1   mov         dword ptr [ebp-14h],25h
20:
21:       char l_str_1[7]="123456";
0040D3B8   mov         ecx,dword ptr [string "123456" (00422e80)]
0040D3BE   mov         dword ptr [ebp-2Ch],ecx
0040D3C1   mov         dx,word ptr [string "123456"+4 (00422e84)]
0040D3C8   mov         word ptr [ebp-28h],dx
0040D3CC   mov         al,[string "123456"+6 (00422e86)]
0040D3D1   mov         byte ptr [ebp-26h],al
22:       char l_str_2[7]={'1','2','3','4','5','6',0};
0040D3D4   mov         byte ptr [ebp-34h],31h
0040D3D8   mov         byte ptr [ebp-33h],32h
0040D3DC   mov         byte ptr [ebp-32h],33h
0040D3E0   mov         byte ptr [ebp-31h],34h
0040D3E4   mov         byte ptr [ebp-30h],35h
0040D3E8   mov         byte ptr [ebp-2Fh],36h
0040D3EC   mov         byte ptr [ebp-2Eh],0
23:       unsigned char l_uchstr[6] = {0x00,0x80,0x92,0x00,0x11,0xfa};
0040D3F0   mov         byte ptr [ebp-3Ch],0
0040D3F4   mov         byte ptr [ebp-3Bh],80h
0040D3F8   mov         byte ptr [ebp-3Ah],92h
0040D3FC   mov         byte ptr [ebp-39h],0
0040D400   mov         byte ptr [ebp-38h],11h
0040D404   mov         byte ptr [ebp-37h],0FAh
24:   }
0040D408   pop         edi
0040D409   pop         esi
0040D40A   pop         ebx
0040D40B   mov         esp,ebp
0040D40D   pop         ebp
0040D40E   ret

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從如下角度考慮:

不同編譯器的處理不一樣。

定義時初始化的效率。
如果初始化的值不會被使用的，這對效率的影響。