Re: AMD64 ABI compatibility

[Nicolas Alt <nalt at apple dot com>]

Thanks for your reply. The gcc compiler uses %rdi, %rsi, %rdx, %rcx  
with -mregparm=4, but MS uses %rcx, %rdx, %r8, %r9, so that won't be  
enough. Also MS requires some space on the stack to be reserved for  
the 4 regs.

Someone has written a wrapper:
http://people.freebsd.org/~wpaul/winx64_wrap.S


On Jul 9, 2007, at 12:58 , Dave Korn wrote:

> On 09 July 2007 20:48, Nicolas Alt wrote:
>
> > Hi!
> >
> > On the AMD64 / x86-64Bit architecture, some arguments of a functions
> > are passed using registers, but there seem to be two different
> > conventions out there. The standard ABI uses 6 registers, but
> > Microsoft compilers use only 4. Because of that, code compiled with
> > gcc cannot call code compiled with a MS compiler without an ugly
> > wrapper.
> >
> > Have there been any efforts to make gcc do function calls the MS way?
> > I guess this would be an important feature for mingw on AMD64.
>
>
>   Does -mregparm=4 do what you want?
>
>
>     cheers,
>       DaveK
> --
> Can't think of a witty .sigline today....