[PATCH] mscoree: Implement VTable fixup for x86_64 architecture.

[Vincent Povirk]

> I have progressed a bit in attempts to load mixed code DLL into 64-bit
> process. To do this I built wine-mono pure assembly dlls (mscorlib and
> others) with -platform:x64 flag which provides x86_64 pure assembly dlls
> and thus allows to workaround DLL load issue.

Interesting. Do you have a patch to Mono that does this?

> In this state ReallyFixupVTable is called from x86_64 thunk, where
> mono_marshal_get_vtfixup_ftnptr() starts executing 64-bit mixed code
> DLL's assembly initialization, but currently fails with my DLL on
> "invalid IL instruction" somewhere around System.IntPtr.ctor call (the
> same class works on i686), which is probably some mono issue. So I
> cannot come up with a fully working test case for now, though I did not
> give up yet.

I can try to build a 64-bit managed C++ dll in visual studio and call
it from a C program.

If Mono still has trouble with that, I think there are ways to use
vtable fixups in (otherwise) pure managed code to export methods to C.

>>> +#elif __x86_64__ /* !defined(__i386__) */
>> Later in the patch it says defined(__x86_64__). I have no idea whether
>> this distinction matters.
>>
> Comments say "defined", while there are #if's. It was originally like
> this when it was __i386__ only, I tried to minimize the changes. #if
> does work both for i386 and x86_64 (though #ifdef would work either).
> Should I fix comments for consistency?

I guess it's not important then. If you're touching those lines
anyway, I guess it makes sense to fix it.

But more importantly, I don't think we should commit this until we can
test it somehow.