汇编角度看函数重载
时间：2010-09-24 来源：老钟古
由汇编代码我们可以清楚的看到，C++中的函数重载对于非对象的重载基本上是一样的，只是在调用的时候采用不同的名称实现（VC++ 6.0实现）
程序的代码：
代码
#include <iostream>
代码
using namespace std;
void output( int x );
void output( float x );
void output( int x ) {
cout << "output int " << x << endl;
}
void output( float x ) {
cout << "output float " << x << endl;
}
int main() {
int x = 1;
float y = 1.0;
output( x );
output( y );
output( 1 );
//output( 0.5 );
output( int( 0.5 ) );
output( float( 0.5 ) );
return 0;
}
两个函数重载的代码：
代码
1 25: void output( int x ) {2 004015A0 push ebp
3 004015A1 mov ebp,esp
4 004015A3 sub esp,40h
5 004015A6 push ebx
6 004015A7 push esi
7 004015A8 push edi
8 004015A9 lea edi,[ebp-40h]
9 004015AC mov ecx,10h
10 004015B1 mov eax,0CCCCCCCCh
11 004015B6 rep stos dword ptr [edi]
12 26: cout << "output int " << x << endl;
13 004015B8 push offset @ILT+200(std::endl) (004010cd)
14 004015BD mov eax,dword ptr [ebp+8]
15 004015C0 push eax
16 004015C1 push offset string "output int " (0046c01c)
17 004015C6 push offset std::cout (004777f0)
18 004015CB call @ILT+655(std::operator<<) (00401294)
19 004015D0 add esp,8
20 004015D3 mov ecx,eax
21 004015D5 call @ILT+255(std::basic_ostream<char,std::char_traits<char> >::operator<<) (00401104)
22 004015DA mov ecx,eax
23 004015DC call @ILT+490(std::basic_ostream<char,std::char_traits<char> >::operator<<) (004011ef)
24 27: }
25 004015E1 pop edi
26 004015E2 pop esi
27 004015E3 pop ebx
28 004015E4 add esp,40h
29 004015E7 cmp ebp,esp
30 004015E9 call __chkesp (00420d20)
31 004015EE mov esp,ebp
32 004015F0 pop ebp
33 004015F1 ret
34
35
36
37 29: void output( float x ) {
38 00401610 push ebp
39 00401611 mov ebp,esp
40 00401613 sub esp,40h
41 00401616 push ebx
42 00401617 push esi
43 00401618 push edi
44 00401619 lea edi,[ebp-40h]
45 0040161C mov ecx,10h
46 00401621 mov eax,0CCCCCCCCh
47 00401626 rep stos dword ptr [edi]
48 30: cout << "output float " << x << endl;
49 00401628 push offset @ILT+200(std::endl) (004010cd)
50 0040162D mov eax,dword ptr [ebp+8]
51 00401630 push eax
52 00401631 push offset string "output float " (0046c02c)
53 00401636 push offset std::cout (004777f0)
54 0040163B call @ILT+655(std::operator<<) (00401294)
55 00401640 add esp,8
56 00401643 mov ecx,eax
57 00401645 call @ILT+305(std::basic_ostream<char,std::char_traits<char> >::operator<<) (00401136)
58 0040164A mov ecx,eax
59 0040164C call @ILT+490(std::basic_ostream<char,std::char_traits<char> >::operator<<) (004011ef)
60 31: }
61 00401651 pop edi
62 00401652 pop esi
63 00401653 pop ebx
64 00401654 add esp,40h
65 00401657 cmp ebp,esp
66 00401659 call __chkesp (00420d20)
67 0040165E mov esp,ebp
68 00401660 pop ebp
69 00401661 ret
70
71
72
函数在进行调用的时候的不同名称：
代码
38: int x = 1;00401698 mov dword ptr [ebp-4],1
39: float y = 1.0;
0040169F mov dword ptr [ebp-8],3F800000h
40: output( x );
004016A6 mov eax,dword ptr [ebp-4]
004016A9 push eax
004016AA call @ILT+260(output) (00401109)
004016AF add esp,4
41: output( y );
004016B2 mov ecx,dword ptr [ebp-8]
004016B5 push ecx
004016B6 call @ILT+165(output) (004010aa)
004016BB add esp,4
42: output( 1 );
004016BE push 1
004016C0 call @ILT+260(output) (00401109)
004016C5 add esp,4
43: //output( 0.5 );
44: output( int( 0.5 ) );
004016C8 push 0
004016CA call @ILT+260(output) (00401109)
004016CF add esp,4
45: output( float( 0.5 ) );
004016D2 push 3F000000h
004016D7 call @ILT+165(output) (004010aa)
004016DC add esp,4
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