Fastcall calling convention

[Damjan Jovanovic]

Hi

Wine doesn't seem to support the fastcall calling convention:

include/winternl.h:
/* These are implemented as __fastcall, so we can't let Winelib apps
link with them */

dlls/hal/hal.c:
#ifdef __i386__
#define DEFINE_FASTCALL1_ENTRYPOINT( name ) \
    __ASM_STDCALL_FUNC( name, 4, \
                       "popl %eax\n\t" \
                       "pushl %ecx\n\t" \
                       "pushl %eax\n\t" \
                       "jmp " __ASM_NAME("__regs_") #name __ASM_STDCALL(4))

GCC seems to support fastcall from version 3.4:
http://www.ohse.de/uwe/articles/gcc-attributes.html

Should we support it? Its absence makes kernel driver code a lot
uglier (eg. irp->Tail.Overlay.s.u2.CurrentStackLocation instead of
IoGetCurrentIrpStackLocation()). We also can't declare fastcall
functions in header files, so some functions that are actually
implemented are missing from header files and thus unusable from
inside Wine.

Thank you
Damjan Jovanovic

[Paul Chitescu]

On Tuesday 23 March 2010 10:59:56 am Damjan Jovanovic wrote:
> Hi
>
> Wine doesn't seem to support the fastcall calling convention:
>
> include/winternl.h:
> /* These are implemented as __fastcall, so we can't let Winelib apps
> link with them */
>
> dlls/hal/hal.c:
> #ifdef __i386__
> #define DEFINE_FASTCALL1_ENTRYPOINT( name ) \
>     __ASM_STDCALL_FUNC( name, 4, \
>                        "popl %eax\n\t" \
>                        "pushl %ecx\n\t" \
>                        "pushl %eax\n\t" \
>                        "jmp " __ASM_NAME("__regs_") #name __ASM_STDCALL(4))
>
> GCC seems to support fastcall from version 3.4:
> http://www.ohse.de/uwe/articles/gcc-attributes.html
>
> Should we support it? Its absence makes kernel driver code a lot
> uglier (eg. irp->Tail.Overlay.s.u2.CurrentStackLocation instead of
> IoGetCurrentIrpStackLocation()). We also can't declare fastcall
> functions in header files, so some functions that are actually
> implemented are missing from header files and thus unusable from
> inside Wine.
>
> Thank you
> Damjan Jovanovic

Unfortunately GCC's fastcall is different from the Microsoft's fastcall so 
it's not usable in exported functions:

http://gcc.gnu.org/ml/gcc-bugs/2009-08/msg00837.html

[Damjan Jovanovic]

On Tue, Mar 23, 2010 at 11:15 AM, Paul Chitescu  wrote:
> On Tuesday 23 March 2010 10:59:56 am Damjan Jovanovic wrote:
> > Hi
> >
> > Wine doesn't seem to support the fastcall calling convention:
> >
> > include/winternl.h:
> > /* These are implemented as __fastcall, so we can't let Winelib apps
> > link with them */
> >
> > dlls/hal/hal.c:
> > #ifdef __i386__
> > #define DEFINE_FASTCALL1_ENTRYPOINT( name ) \
> >     __ASM_STDCALL_FUNC( name, 4, \
> >                        "popl %eax\n\t" \
> >                        "pushl %ecx\n\t" \
> >                        "pushl %eax\n\t" \
> >                        "jmp " __ASM_NAME("__regs_") #name __ASM_STDCALL(4))
> >
> > GCC seems to support fastcall from version 3.4:
> > http://www.ohse.de/uwe/articles/gcc-attributes.html
> >
> > Should we support it? Its absence makes kernel driver code a lot
> > uglier (eg. irp->Tail.Overlay.s.u2.CurrentStackLocation instead of
> > IoGetCurrentIrpStackLocation()). We also can't declare fastcall
> > functions in header files, so some functions that are actually
> > implemented are missing from header files and thus unusable from
> > inside Wine.
> >
> > Thank you
> > Damjan Jovanovic
>
> Unfortunately GCC's fastcall is different from the Microsoft's fastcall so
> it's not usable in exported functions:
>
> http://gcc.gnu.org/ml/gcc-bugs/2009-08/msg00837.html

Those differences seem to only feature when passing/returning
structures/floats by value, something the Windows DDK should never do.

Also can we declare some fastcall functions inline, like winternl.h
has done for RtlUshortByteSwap()?

Thank you
Damjan Jovanovic