C语言调规则浅析

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函数调用中参数是通过堆栈或/和寄存器来传递的，根据调用时由调用函数或被调用函数来恢复堆栈，分为Standard和C两种调用规则，FASTCALL可以看作是Standard的特殊形式。

32 位 C语言编译器支持的调用规则有 __stdcall (Standard), __cdecl (C) 和 __fastcall (FASTCALL), __cdecl为缺省值。

三种调用规则的特点如下：

C语言调用规则调用规测函数命名进栈顺序堆栈清理特点 __stdcall 函数名前加下划线"_",后加"@"和参数字节数从右到左被调用函数堆栈清理代码只有一份，代码小，只能支持固定参数 __fastcall 函数名前加下划线"_",后加"@"和参数字节数

右边两个能装入寄存器的参数进寄存器，其余参数从右到左进栈

被调用函数通过寄存器传递参数，速度快 __cdecl 函数名前加下划线"_" 从右到左调用函数编译器为每次调用都生成堆栈清理代码，支持可变参数，如printf()

以下简单的C程序和相应的汇编代码展示了三种调用规则的细节。

* callconv - Calling Conventions

int __stdcall stdcall_function(int p1, int p2)

{

int n1;

int n2;

int ret;

n1 = p1;

n2 = p2;

ret = n1 + n2;

return 0;

}

int __cdecl cdecl_function(int p1, int p2)

{

int n1, n2;

int ret;

n1 = p1;

n2 = p2;

ret = n1 + n2;

return ret;

}

int __cdecl cdecl_function_v(int p1, int p2, int v, ...)

{

int n1, n2;

int ret;

n1 = p1;

n2 = p2;

ret = n1 + n2 + v;

return ret;

}

int __fastcall fastcall_function(int p1, double d1, int p2, double d2, int p3)

{

int n1, n2;

double d;

int ret;

d = d1 + d2;

n1 = p1;

n2 = p2;

ret = n1 + n2 + p3;

return ret ;

}

int add(int p1, int p2)

{

return (p1 + p2);

}

int main(void)

{

int m, m1 = 1, m2 = 2, m3 = 3, m4 = 4;

double d1, d2;

d1 = 1.0;

d2 = 2.0;

m = stdcall_function(m1, m2);

m = cdecl_function(m1, m2);

m = cdecl_function_v(m1, m2, m3);

m = cdecl_function_v(m1, m2, m3, m4);

m = fastcall_function(m1, d1, m2, d2, m3);

return 0;

}

TITLE C:Documents and Settings ootsrccallconvcallconv.c

.386P

include listing.inc

if @Version gt 510

.model FLAT

else

_TEXT SEGMENT PARA USE32 PUBLIC 'CODE'

_TEXT ENDS

_DATA SEGMENT DWORD USE32 PUBLIC 'DATA'

_DATA ENDS

CONST SEGMENT DWORD USE32 PUBLIC 'CONST'

CONST ENDS

_BSS SEGMENT DWORD USE32 PUBLIC 'BSS'

_BSS ENDS

_TLS SEGMENT DWORD USE32 PUBLIC 'TLS'

_TLS ENDS

FLAT GROUP _DATA, CONST, _BSS

ASSUME CS: FLAT, DS: FLAT, SS: FLAT

endif

PUBLIC _stdcall_function@8

_TEXT SEGMENT

_p1$ = 8

_p2$ = 12

_n1$ = -12

_n2$ = -4

_ret$ = -8

_stdcall_function@8 PROC NEAR

; 6 : {

push ebp

mov ebp, esp

sub esp, 12 ; 0000000cH

; 7 : int n1;

; 8 : int n2;

; 9 : int ret;

; 10 :

; 11 : n1 = p1;

mov eax, DWORD PTR _p1$[ebp]

mov DWORD PTR _n1$[ebp], eax

; 12 : n2 = p2;

mov ecx, DWORD PTR _p2$[ebp]

mov DWORD PTR _n2$[ebp], ecx

; 13 :

; 14 : ret = n1 + n2;

mov edx, DWORD PTR _n1$[ebp]

add edx, DWORD PTR _n2$[ebp]

mov DWORD PTR _ret$[ebp], edx

; 15 :

; 16 : return 0;

xor eax, eax

; 17 : }

mov esp, ebp

pop ebp

ret 8

_stdcall_function@8 ENDP

_TEXT ENDS

PUBLIC _cdecl_function

_TEXT SEGMENT

_p1$ = 8

_p2$ = 12

_n1$ = -12

_n2$ = -4

_ret$ = -8

_cdecl_function PROC NEAR

; 20 : {

push ebp

mov ebp, esp

sub esp, 12 ; 0000000cH

; 21 : int n1, n2;

; 22 :

; 23 : int ret;

; 24 :

; 25 : n1 = p1;

mov eax, DWORD PTR _p1$[ebp]

mov DWORD PTR _n1$[ebp], eax

; 26 : n2 = p2;

mov ecx, DWORD PTR _p2$[ebp]

mov DWORD PTR _n2$[ebp], ecx

; 27 :

; 28 : ret = n1 + n2;

mov edx, DWORD PTR _n1$[ebp]

add edx, DWORD PTR _n2$[ebp]

mov DWORD PTR _ret$[ebp], edx

; 29 :

; 30 : return ret;

mov eax, DWORD PTR _ret$[ebp]

; 31 : }

mov esp, ebp

pop ebp

ret 0

_cdecl_function ENDP

_TEXT ENDS

PUBLIC _cdecl_function_v

_TEXT SEGMENT

_p1$ = 8

_p2$ = 12

_v$ = 16

_n1$ = -12

_n2$ = -4

_ret$ = -8

_cdecl_function_v PROC NEAR

; 34 : {

push ebp

mov ebp, esp

sub esp, 12 ; 0000000cH

; 35 : int n1, n2;

; 36 :

; 37 : int ret;

; 38 :

; 39 : n1 = p1;

mov eax, DWORD PTR _p1$[ebp]

mov DWORD PTR _n1$[ebp], eax

; 40 : n2 = p2;

mov ecx, DWORD PTR _p2$[ebp]

mov DWORD PTR _n2$[ebp], ecx

; 41 :

; 42 : ret = n1 + n2 + v;

mov edx, DWORD PTR _n1$[ebp]

add edx, DWORD PTR _n2$[ebp]

add edx, DWORD PTR _v$[ebp]

mov DWORD PTR _ret$[ebp], edx

; 43 :

; 44 : return ret;

mov eax, DWORD PTR _ret$[ebp]

; 45 : }

mov esp, ebp

pop ebp

ret 0

_cdecl_function_v ENDP

_TEXT ENDS

PUBLIC @fastcall_function@28

EXTRN __fltused:NEAR

_TEXT SEGMENT

_p1$ = -24

_d1$ = 8

_p2$ = -28

_d2$ = 16

_p3$ = 24

_n1$ = -20

_n2$ = -4

_d$ = -12

_ret$ = -16

@fastcall_function@28 PROC NEAR

; 48 : {

push ebp

mov ebp, esp

sub esp, 28 ; 0000001cH

mov DWORD PTR _p2$[ebp], edx

mov DWORD PTR _p1$[ebp], ecx

; 49 : int n1, n2;

; 50 : double d;

; 51 :

; 52 : int ret;

; 53 :

; 54 : d = d1 + d2;

fld QWORD PTR _d1$[ebp]

fadd QWORD PTR _d2$[ebp]

fstp QWORD PTR _d$[ebp]

; 55 :

; 56 : n1 = p1;

mov eax, DWORD PTR _p1$[ebp]

mov DWORD PTR _n1$[ebp], eax

; 57 : n2 = p2;

mov ecx, DWORD PTR _p2$[ebp]

mov DWORD PTR _n2$[ebp], ecx

; 58 :

; 59 : ret = n1 + n2 + p3;

mov edx, DWORD PTR _n1$[ebp]

add edx, DWORD PTR _n2$[ebp]

add edx, DWORD PTR _p3$[ebp]

mov DWORD PTR _ret$[ebp], edx

; 60 :

; 61 : return ret ;

mov eax, DWORD PTR _ret$[ebp]

; 62 : }

mov esp, ebp

pop ebp

ret 20 ; 00000014H

@fastcall_function@28 ENDP

_TEXT ENDS

PUBLIC _add

_TEXT SEGMENT

_p1$ = 8

_p2$ = 12

_add PROC NEAR

; 65 : {

push ebp

mov ebp, esp

; 66 : return (p1 + p2);

mov eax, DWORD PTR _p1$[ebp]

add eax, DWORD PTR _p2$[ebp]

; 67 : }

pop ebp

ret 0

_add ENDP

_TEXT ENDS

PUBLIC _main

_TEXT SEGMENT

_m$ = -32

_m1$ = -20

_m2$ = -24

_m3$ = -28

_m4$ = -36

_d1$ = -8

_d2$ = -16

_main PROC NEAR

; 70 : {

push ebp

mov ebp, esp

sub esp, 36 ; 00000024H

; 71 : int m, m1 = 1, m2 = 2, m3 = 3, m4 = 4;

mov DWORD PTR _m1$[ebp], 1

mov DWORD PTR _m2$[ebp], 2

mov DWORD PTR _m3$[ebp], 3

mov DWORD PTR _m4$[ebp], 4

; 72 :

; 73 : double d1, d2;

; 74 :

; 75 : d1 = 1.0;

mov DWORD PTR _d1$[ebp], 0

mov DWORD PTR _d1$[ebp+4], 1072693248 ; 3ff00000H

; 76 : d2 = 2.0;

mov DWORD PTR _d2$[ebp], 0

mov DWORD PTR _d2$[ebp+4], 1073741824 ; 40000000H

; 77 :

; 78 : m = stdcall_function(m1, m2);

mov eax, DWORD PTR _m2$[ebp]

push eax

mov ecx, DWORD PTR _m1$[ebp]

push ecx

call _stdcall_function@8

mov DWORD PTR _m$[ebp], eax

; 79 :

; 80 : m = cdecl_function(m1, m2);

mov edx, DWORD PTR _m2$[ebp]

push edx

mov eax, DWORD PTR _m1$[ebp]

push eax

call _cdecl_function

add esp, 8

mov DWORD PTR _m$[ebp], eax

; 81 :

; 82 : m = cdecl_function_v(m1, m2, m3);

mov ecx, DWORD PTR _m3$[ebp]

push ecx

mov edx, DWORD PTR _m2$[ebp]

push edx

mov eax, DWORD PTR _m1$[ebp]

push eax

call _cdecl_function_v

add esp, 12 ; 0000000cH

mov DWORD PTR _m$[ebp], eax

; 83 :

; 84 : m = cdecl_function_v(m1, m2, m3, m4);

mov ecx, DWORD PTR _m4$[ebp]

push ecx

mov edx, DWORD PTR _m3$[ebp]

push edx

mov eax, DWORD PTR _m2$[ebp]

push eax

mov ecx, DWORD PTR _m1$[ebp]

push ecx

call _cdecl_function_v

add esp, 16 ; 00000010H

mov DWORD PTR _m$[ebp], eax

; 85 :

; 86 : m = fastcall_function(m1, d1, m2, d2, m3);

mov edx, DWORD PTR _m3$[ebp]

push edx

mov eax, DWORD PTR _d2$[ebp+4]

push eax

mov ecx, DWORD PTR _d2$[ebp]

push ecx

mov edx, DWORD PTR _m2$[ebp]

mov eax, DWORD PTR _d1$[ebp+4]

push eax

mov ecx, DWORD PTR _d1$[ebp]

push ecx

mov ecx, DWORD PTR _m1$[ebp]

call @fastcall_function@28

mov DWORD PTR _m$[ebp], eax

; 87 :

; 88 : return 0;

xor eax, eax

; 89 : }

mov esp, ebp

pop ebp

ret 0

_main ENDP

_TEXT ENDS

END