Windows32 API: "mov edi,edi" on function entry?

Posted by Ira Baxter on Stack Overflow See other posts from Stack Overflow or by Ira Baxter
Published on 2012-07-05T03:09:11Z Indexed on 2012/07/05 3:15 UTC
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Windows

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calling-convention

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seh

I'm stepping through Structured Error Handling recovery code in Windows 7 (e.g, what happens after SEH handler is done and passes back "CONTINUE" code). Here's a function which is called:

 7783BD9F  mov         edi,edi  
 7783BDA1  push        ebp 
 7783BDA2  mov         ebp,esp   
 7783BDA4  push        1  
 7783BDA6  push        dword ptr [ebp+0Ch]  
 7783BDA9  push        dword ptr [ebp+8]  
 7783BDAC  call        778692DF  
 7783BDB1  pop         ebp  
 7783BDB2  ret         8

I'm used to the function prolog of "push ebp/mov ebp,esp". What's the purpose of the "mov edi,edi"?

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