函数调用方式__stdecl _stdcall _fastcall __thiscall介绍

 

        __cdecl 是C DECLaration的缩写(declaration,声明),表示C语言默认的函数调用方法:所有参数从右到左依次入栈,这些参数由调用者清除,称为手动清栈。被调用函数不会要求调用者传递多少参数,调用者传递过多或者过少的参数,甚至完全不同的参数都不会产生编译阶段的错误。

 

_stdcall 是StandardCall的缩写,是C++的标准调用方式:所有参数从右到左依次入栈,如果是调用类成员的话,最后一个入栈的是this指针。这些堆栈中的参数由被调用的函数在返回时清除,使用的指令是 retnX,X表示参数占用的字节数,CPU在ret之后自动弹出X个字节的堆栈空间。称为自动清栈。函数在编译的时候就必须确定参数个数,并且调用者必须严格的控制参数的生成,不能多,不能少,否则返回后会出错。

 

_fastcall 是编译器指定的快速调用方式。由于大多数的函数参数个数很少,使用堆栈传递比较费时。因此_fastcall通常规定将前两个(或若干个)参数由寄存器传递,其余参数还是通过堆栈传递。不同编译器编译的程序规定的寄存器不同。返回方式和_stdcall相当。

 

 

   __thiscall 是为了解决类成员调用中this指针传递而规定的。__thiscall要求把this指针放在特定寄存器中,该寄存器由编译器决定。VC使用ecx,Borland的C++编译器使用eax。返回方式和_stdcall相当。

 

 

  _fastcall__thiscall涉及的寄存器由编译器决定,因此不能用作跨编译器的接口。所以Windows上的COM对象接口都定义为_stdcall调用方式。

 

 

调用类型

参数入栈顺序

由谁负责清栈

寄存器传递

__stdecl

从右到左依次入栈

调用函数

this

_stdcall 

从右到左依次入栈

调用函数

this

_fastcall

从右到左依次入栈

调用函数

this  和参数

__thiscall

从右到左依次入栈

调用函数

this

默认(vs2005)

从右到左依次入栈

调用函数

this

 

 

 

 

 

 

 

 

下面来通过代码来查看一下他们到底是如何传递参数和出入栈:

 

 

class TestCallType { public: int default_call(int ,int); int __cdecl __cdecl_call(int a, int b); int _stdcall _stdcall_call(int a, int b); int _fastcall _fastcall_call(int a, int b); int __thiscall _thiscall_call(int,int); int x; }; int TestCallType::default_call(int a, int b) { this->x = a + b; return this->x; } int TestCallType::__cdecl_call(int a, int b) { this->x = a + b; return this->x; } int TestCallType::_stdcall_call(int a, int b) { this->x = a + b; return this->x; } int TestCallType::_fastcall_call(int a, int b) { this->x = a + b; return this->x; } int TestCallType::_thiscall_call(int a, int b) { this->x = a + b; return this->x; } 

 

调用的地方反汇编出来如下:

int _tmain(int argc, _TCHAR* argv[]) { 004115B0 push ebp 004115B1 mov ebp,esp 004115B3 sub esp,0CCh 004115B9 push ebx 004115BA push esi 004115BB push edi 004115BC lea edi,[ebp-0CCh] 004115C2 mov ecx,33h 004115C7 mov eax,0CCCCCCCCh 004115CC rep stos dword ptr es:[edi] TestCallType call_type; call_type.default_call(1, 2); 004115CE push 2 /* 参数入栈 */ 004115D0 push 1 /* 参数入栈 */ 004115D2 lea ecx,[call_type] /* this指针 */ 004115D5 call TestCallType::default_call (411113h) call_type.__cdecl_call(1, 2); 004115DA push 2 /* 参数入栈 */ 004115DC push 1 /* 参数入栈 */ 004115DE lea eax,[call_type] /* this指针 */ 004115E1 push eax 004115E2 call TestCallType::__cdecl_call (41112Ch) 004115E7 add esp,0Ch /* 调用者负责清栈 */ call_type._fastcall_call(1,2); 004115EA push 2 /* 参数入栈 */ 004115EC mov edx,1 /* 第一个参数通过寄存器传递 */ 004115F1 lea ecx,[call_type] /* this指针 */ 004115F4 call TestCallType::_fastcall_call (41100Ah) call_type._stdcall_call(1,2); 004115F9 push 2 004115FB push 1 004115FD lea eax,[call_type] /* this指针 */ 00411600 push eax 00411601 call TestCallType::_stdcall_call (4110EBh) call_type._thiscall_call(1, 2); 00411606 push 2 00411608 push 1 0041160A lea ecx,[call_type] /* this指针 */ 0041160D call TestCallType::_thiscall_call (41117Ch) return 0; 0041161E xor eax,eax } 

 

函数定义的地方反汇编:

int TestCallType::default_call(int a, int b) { 004113D0 push ebp 004113D1 mov ebp,esp 004113D3 sub esp,0CCh 004113D9 push ebx 004113DA push esi 004113DB push edi 004113DC push ecx 004113DD lea edi,[ebp-0CCh] 004113E3 mov ecx,33h 004113E8 mov eax,0CCCCCCCCh 004113ED rep stos dword ptr es:[edi] 004113EF pop ecx 004113F0 mov dword ptr [ebp-8],ecx this->x = a + b; 004113F3 mov eax,dword ptr [a] 004113F6 add eax,dword ptr [b] 004113F9 mov ecx,dword ptr [this] 004113FC mov dword ptr [ecx],eax return this->x; 004113FE mov eax,dword ptr [this] 00411401 mov eax,dword ptr [eax] } 00411403 pop edi 00411404 pop esi 00411405 pop ebx 00411406 mov esp,ebp 00411408 pop ebp /* 默认调用是_stdcall 被调用函数负责清栈 */ 00411409 ret 8 --- No source file ------------------------------------------------------------- int TestCallType::__cdecl_call(int a, int b) { 00411420 push ebp 00411421 mov ebp,esp 00411423 sub esp,0C0h 00411429 push ebx 0041142A push esi 0041142B push edi 0041142C lea edi,[ebp-0C0h] 00411432 mov ecx,30h 00411437 mov eax,0CCCCCCCCh 0041143C rep stos dword ptr es:[edi] this->x = a + b; 0041143E mov eax,dword ptr [a] 00411441 add eax,dword ptr [b] 00411444 mov ecx,dword ptr [this] 00411447 mov dword ptr [ecx],eax return this->x; 00411449 mov eax,dword ptr [this] 0041144C mov eax,dword ptr [eax] } 0041144E pop edi 0041144F pop esi 00411450 pop ebx 00411451 mov esp,ebp 00411453 pop ebp 00411454 ret /* __cdecl 不用负责栈清除 */ --- No source file ------------------------------------------------------------- int TestCallType::_stdcall_call(int a, int b) { 00411470 push ebp 00411471 mov ebp,esp 00411473 sub esp,0C0h 00411479 push ebx 0041147A push esi 0041147B push edi 0041147C lea edi,[ebp-0C0h] 00411482 mov ecx,30h 00411487 mov eax,0CCCCCCCCh 0041148C rep stos dword ptr es:[edi] this->x = a + b; 0041148E mov eax,dword ptr [a] 00411491 add eax,dword ptr [b] 00411494 mov ecx,dword ptr [this] 00411497 mov dword ptr [ecx],eax return this->x; 00411499 mov eax,dword ptr [this] 0041149C mov eax,dword ptr [eax] } 0041149E pop edi 0041149F pop esi 004114A0 pop ebx 004114A1 mov esp,ebp 004114A3 pop ebp 004114A4 ret 0Ch //清除栈,字节数和参数入栈对应 --- No source file ------------------------------------------------------------- int TestCallType::_fastcall_call(int a, int b) { 004114C0 push ebp 004114C1 mov ebp,esp 004114C3 sub esp,0D8h 004114C9 push ebx 004114CA push esi 004114CB push edi 004114CC push ecx 004114CD lea edi,[ebp-0D8h] 004114D3 mov ecx,36h 004114D8 mov eax,0CCCCCCCCh 004114DD rep stos dword ptr es:[edi] 004114DF pop ecx 004114E0 mov dword ptr [ebp-8],edx 004114E3 mov dword ptr [ebp-14h],ecx this->x = a + b; 004114E6 mov eax,dword ptr [a] 004114E9 add eax,dword ptr [b] 004114EC mov ecx,dword ptr [this] 004114EF mov dword ptr [ecx],eax return this->x; 004114F1 mov eax,dword ptr [this] 004114F4 mov eax,dword ptr [eax] } 004114F6 pop edi 004114F7 pop esi 004114F8 pop ebx 004114F9 mov esp,ebp 004114FB pop ebp 004114FC ret 4 //清除栈,字节数和参数入栈对应 --- No source file ------------------------------------------------------------- int TestCallType::_thiscall_call(int a, int b) { 00411510 push ebp 00411511 mov ebp,esp 00411513 sub esp,0CCh 00411519 push ebx 0041151A push esi 0041151B push edi 0041151C push ecx 0041151D lea edi,[ebp-0CCh] 00411523 mov ecx,33h 00411528 mov eax,0CCCCCCCCh 0041152D rep stos dword ptr es:[edi] 0041152F pop ecx 00411530 mov dword ptr [ebp-8],ecx this->x = a + b; 00411533 mov eax,dword ptr [a] 00411536 add eax,dword ptr [b] 00411539 mov ecx,dword ptr [this] 0041153C mov dword ptr [ecx],eax return this->x; 0041153E mov eax,dword ptr [this] 00411541 mov eax,dword ptr [eax] } 00411543 pop edi 00411544 pop esi 00411545 pop ebx 00411546 mov esp,ebp 00411548 pop ebp 00411549 ret 8 //清除栈,字节数和参数入栈对应 --- No source file ------------------------------------------------------------- 

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