x86 procedure calling convention (again)

[phi gcc]

Hi All,

Is there a documnent or a way to know the various procedure calling
convention used by gcc over time (i.e by gcc version) for regular
compile, fastcall, (eventually static function).

For instance I got occurences of some gcc version that do
a0 in ax, a1 in dx, a2 in 0(sp), a3 in 4(sp)   ...

and other occurences that do
a0 in cx, a1 in dx, a2 in 0(sp), a3 in 4(sp)   ...

Any hints appreciated.
Cheers,
Phi