Fastcall calling convention

[Damjan Jovanovic]

On Tue, Mar 23, 2010 at 11:15 AM, Paul Chitescu <paulc at voip.null.ro> 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