[MLton] Support for link options in ML Basis files
Tue, 18 Jan 2005 09:55:22 -0800
> > Can we avoid portability problems by automatically generating a
> > wrapper to translate between the calling convention we understand
> > (n-ary C functions with basic types) and the calling convention we
> > don't (passing C structs)?
> That is an option.
> The problem is that on the ML side, ML-NLFFI always passes structs/unions
> around as pointers.
The approach I proposed seems easier, although both work. I think the
difference is in who allocates space for the struct. In my approach,
the struct is allocated on the stack on the C side and then
immediately flattened to pass to the funtion. In their approach, if I
understand correctly, the struct is allocated on the SML side (using
malloc? or SML/NJ alloc?) and then flattened on the C side to pass to
the function. Hopefully my approach will be faster because gcc can
optimize away the struct entirely, and just shuffle the args to
translate between the n-ary calling convention and the struct calling
I guess the problem is that you will have to modify ML-NLFFI to do
> > Might it work to use the same approach that we use for
> > build/lib/<target>/constants?
> Depends what you mean? I believe the hope is that the programmer doesn't
> need to specify which #define constants should be exported, but that might
> be too much to ask of a tool.
Yeah, it doesn't seem too much to ask for the programmer to specify
which constants they want.