Je precise que j'ai jamais essayer le ./4 :

Using the built-in functions described below, you can record the
arguments a function received, and call another function with the same
arguments, without knowing the number or types of the arguments.

You can also record the return value of that function call, and
later return that value, without knowing what data type the function
tried to return (as long as your caller expects that data type).

- Built-in Function: void * __builtin_apply_args ()
This built-in function returns a pointer to data describing how to
perform a call with the same arguments as were passed to the
current function.

The function saves the arg pointer register, structure value
address, and all registers that might be used to pass arguments to
a function into a block of memory allocated on the stack. Then it
address, and all registers that might be used to pass arguments to
a function into a block of memory allocated on the stack. Then it
returns the address of that block.

- Built-in Function: void * __builtin_apply (void (*FUNCTION)(), void
*ARGUMENTS, size_t SIZE)
This built-in function invokes FUNCTION with a copy of the
parameters described by ARGUMENTS and SIZE.

The value of ARGUMENTS should be the value returned by
`__builtin_apply_args'. The argument SIZE specifies the size of
the stack argument data, in bytes.

This function returns a pointer to data describing how to return
whatever value was returned by FUNCTION. The data is saved in a
block of memory allocated on the stack.

It is not always simple to compute the proper value for SIZE. The
value is used by `__builtin_apply' to compute the amount of data
that should be pushed on the stack and copied from the incoming
argument area.
- Built-in Function: void __builtin_return (void *RESULT)
This built-in function returns the value described by RESULT from
the containing function. You should specify, for RESULT, a value
returned by `__builtin_apply'.