What is the point of calling conventions and which one to use?

Question

What is the purpose of calling conventions __fastcall, __stdcall, __thiscall, __cdecl, __fastcall and how to know which one to use?

For example, in some function that needs to be called faster (I could use inline but I’m avoiding for bug problems in the compilation), by name I would use __fastcall, but I don’t know if really that’s what it does or if it can cause some problem in the function.

Answer 1

This serves for the compiler to generate correct code to pass the parameters to a function even though the routine has been compiled by another compiler. You can find more information about this here: https://en.wikibooks.org/wiki/X86_Disassembly/Calling_Conventions