fastcall调用约定详解（VC与Delphi）_delphi fastcall-优快云博客

本文链接：https://blog.youkuaiyun.com/zhangmiaoping23/article/details/14127183

本文深入探讨fastcall调用约定在不同语言环境下的应用，以VC和Delphi为例，详细解析其参数传递机制、函数名修改规则及堆栈操作，帮助开发者理解并高效使用这一技术特性。

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fastcall调用约定

1.函数的前几个参数通过寄存器传递，其他参数通过堆栈.
2.被调用函数清理堆栈
3.函数名修改规则同stdcall

VC中的fastcall.

Add(1,2,3,4,5);
00417B83 push        5
00417B85 push        4
00417B87 push        3
00417B89 mov         edx,2
00417B8E mov         ecx,1
00417B93 call        Add (411749h)

int _fastcall Add(int n1,int n2,int n3,int n4,int n5)
{
00417B10 push        ebp
00417B11 mov         ebp,esp
00417B13 sub         esp,0D8h
00417B19 push        ebx
00417B1A push        esi
00417B1B push        edi
00417B1C push        ecx
00417B1D lea         edi,[ebp-0D8h]
00417B23 mov         ecx,36h
00417B28 mov         eax,0CCCCCCCCh
00417B2D rep stos    dword ptr es:[edi]
00417B2F pop         ecx
00417B30 mov         dword ptr [ebp-14h],edx
00417B33 mov         dword ptr [ebp-8],ecx
return n1+n2+n3+n4+n5;
00417B36 mov         eax,dword ptr [n1]
00417B39 add         eax,dword ptr [n2]
00417B3C add         eax,dword ptr [n3]
00417B3F add         eax,dword ptr [n4]
00417B42 add         eax,dword ptr [n5]
}
00417B45 pop         edi
00417B46 pop         esi
00417B47 pop         ebx
00417B48 mov         esp,ebp
00417B4A pop         ebp
00417B4B ret         0Ch

delphi中的fastcall.

Add(1,2,3,4,5);
00451F91   6A04                   push    $04
00451F93   6A05                   push    $05
00451F95   B903000000             mov     ecx, $00000003
00451F9A   BA02000000             mov     edx, $00000002
00451F9F   B801000000             mov     eax, $00000001

|
00451FA4 E8C7FFFFFF call 00451F70

function Add(n1,n2,n3,n4,n5:Integer):Integer;
demoform.pas.35: begin
00451F70 55                   push ebp
00451F71 8BEC             mov ebp,esp
demoform.pas.36: Result:=n1+n2+n3+n4+n5;
00451F73 03D0             add edx,eax
00451F75 03CA             add ecx,edx
00451F77 034D0C        add ecx,[ebp+$0c]
00451F7A 034D08         add ecx,[ebp+$08]
00451F7D 8BC1             mov eax,ecx
demoform.pas.37: end;
00451F7F 5D                 pop ebp
00451F80 C20800        ret $0008