如何知道第一个函数参数在哪里？ [英] How to know where's the first function argument?

问题描述

  PUSH EBP 
 MOV EBP，ESP 
 SUB ESP，8 
 LEAVE 
 RETN 8 
  

并接受两个4字节的参数。看来第一个参数是 EBP + 8 ，第二个参数是 EBP + 12 。但是，如何知道这一点？因为如果函数需要三个4字节的参数，那么第三个参数将位于 EBP + 16 。第一个参数是否总是在 EBP + 8 中，然后我只需添加参数大小即可获得下一个参数？如果是的话，为什么8？

感谢您提前致谢。 当使用堆栈帧时，第一个 stack 参数将始终位于 [EBP + 8] 处，但调用约定可以在两个寄存器中传递参数目的和SIMD）和堆栈上。

这个例子假设你使用了一个标准化的约定，比如 __ stdcall ， __ cdecl ，但是在 __ fastcall 和VC ++ 13新的 __ vectorcall 中的参数将用于通用SIMD寄存器（并且寄存器本身基于ABI Sys-V与MS不同）。

I was just wondering, If I have this ASM function:

PUSH EBP
MOV EBP, ESP
SUB ESP, 8
LEAVE
RETN 8

That does nothing and takes two 4-bytes arguments. It seems that the first argument is at EBP+8 and the second at EBP+12. But, how to know that? Because if the function takes three 4-bytes parameters, then the third will be at EBP+16. Will the first argument be always at EBP+8 and then I just have to add the argument size to get the next one? If yes, why 8?

Thanks in advance.

解决方案

The first stack argument will always be at [EBP+8] when using a stack frame, but calling conventions can pass arguments in both registers (general purpose and SIMD) and on the stack.

This your example assume you use a standardized convention such as __stdcall, __cdecl but arguments in __fastcall and VC++13's new __vectorcall will be in general purpose and SIMD registers respectively (and the registers themselves differ based on ABI Sys-V vs MS).

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