Ok wth is this...

[amadmonk]

I thought I knew my calling conventions... I know my __cdecl from my __stdcall, I know how __thiscall works. I even know the rarely-used __fastcall. But what the hell is this??

; Attributes: bp-based frame

sub_6A9290 proc near

var_2D0= qword ptr -2D0h
var_2BC= byte ptr -2BCh
var_2B4= dword ptr -2B4h
var_9C= dword ptr -9Ch
var_90= dword ptr -90h
var_8C= dword ptr -8Ch
var_18= dword ptr -18h
var_14= dword ptr -14h
var_10= dword ptr -10h
var_9= byte ptr -9
var_8= dword ptr -8
var_4= dword ptr -4
arg_0= dword ptr  8

push    ebp
mov     ebp, esp
sub     esp, 2BCh
push    ebx
push    esi
push    edi
push    0BE0h
mov     edi, eax
mov     eax, [edi+4]

Note that eax is passed in and used as-is. This doesn't conform to any of the cconvs I'm aware of, yet I've seen it a couple of times in the WoW code and it's throwing me for a loop.

Anyone? I can certainly account for eax here, but it makes me curious. Has WoW invented a new calling convention, or is there more here than meets the eye?

EDIT: reading x86 calling conventions - Wikipedia, the free encyclopedia, it appears that there are a LOT of calling conventions that I wasn't aware of (who knew?). But come on... is WoW really written in Delphi?

[Parog]

is WoW really written in Delphi?

Mods let this one go by for trolling purposes, didn't they?

[Apoc]

Mods let this one go by for trolling purposes, didn't they?

Erm... no?

It's a valid question.

[Cypher]

If a routine is internal to the software and all possible control paths are known at compile/link time then the compiler doesn't have to use any standard conventions. PGO for example uses REALLY ****ed up calling conventions.

Calling conventions are there to allow you to call arbitrary functions in external code. If the code is purely internal then it doesn't have to be one of the standard conventions.

Mods let this one go by for trolling purposes, didn't they?

Protip: If you don't understand the topic then don't post. Otherwise you just look retarded.

[amadmonk]

Hmm, that makes sense. I guess I'd been relying upon calling conventions being static, but what you say is truth: it's only crucial for external calls. Profile-guided optimization is a very good example and makes sense (hell, even LTCG could conceivably come up with something nasty if it detected that no externally-accessible call graph could hit the optimized code without going through another block that "understood" the optimization).

Thanks for the clarification; makes sense now.

[Cypher]

No problemo.