Requesting D ABI clarifications

[pragma]

Gotcha. :)  

Sorry about the disinformation there, and thanks for shedding some light on all
this.

- Eric

In article <e443as$1kmt$1 at digitaldaemon.com>, Walter Bright says...
>
>pragma wrote:
>> Well, I do know that there are some variations in how D is supported across
>> Windows and Linux.  I say this because Walter himself seems rather dubious that
>> aiming for cross-platform runtime linking (ala DDL) is "folly" since there are
>> subtle differences.  While I'd like to maintain that this only applies under
>> certain circumstances, I honestly don't know what the baseline for binary
>> compatiblity really is.
>
>The baseline is being ABI compatible with the host C compiler on the 
>target platform.
>
>> A) I think you're on the right track with using eax. It was mentioned some time
>> ago that the *first* parameter of any function/method signature is placed into
>> eax rather than on the stack.  I believe that eax is also used for return values
>> - no suprises there. :)
>
>Actually, the *last* parameter goes into EAX, if it fits.
>
>> B) If memory serves, I think Walter went on the record as saying that the
>> exception handling mechanisms are *different* between win32 and linux (the
>> latter having to do with GDC/GDB compatibility I guess).  I hope I'm wrong about
>> that, as this just seems to make life harder than necessary.  IMNSHO, using
>> separate SEH mechanisms kind of ruins the idea of a true ABI.
>
>They are different. Win32 uses the NT SEH, which has no counterpart on 
>linux. For linux, I would use g++'s .eh_frame method, but it is (as far 
>as I can tell) completely undocumented. So I gave up on that, and simply 
>used what I'd invented for C++ exceptions on 32 bit DOSX.
>
>The code to make it work is in phobos/internal/deh2.d.
>
>> Other things, I've learned through a good amount of hacking. But they really
>> center around how OMF objects are generated - I'm still learning the ELF side of
>> things, but so far there aren't many suprises.
>> 
>> Personally, I'd like to know more, and to see more of the ABI fleshed out so I
>> can make some sound technical decisions in my project.  Like you, I'd rather not
>> just poke around in the dark and make reccomendations and decisions based on
>> what just happens to work.
>> 
>> - EricAnderton at yahoo