Re: Specifying parameter passing convention and place (register)

[Kilgallen@SpamCop.net (Larry Kilgallen)]

In article <opsarq03jtp4pfvb@bram-2>, "Nick Roberts" <nick.roberts@acm.org> writes:
> On 6 Jul 2004 23:14:19 -0500, Larry Kilgallen <Kilgallen@SpamCop.net>  
> wrote:
> 
>>> Where would I find the documentation for this, please? I have
>>> sought but not found.
>>
>> I would presume it is in the GNAT documentation.
> 
> Hehe. First place I looked Larry ;-)

Well, of course GNAT comes with source, right ?   :-)
 
> Unfortunately, the GNAT documentation simply refers the reader to the DEC  
> documentation, and I cannot find the DEC documentation anywhere :-(

The design of the World Wide Web envisioned that URLs would be somewhat
invisible to readers and clicking links would get you there.  I presume
that works if you work your way through the whole web hierarchy to what
you want, but if you want the following shortcut it is somewhat weirdly
named:

	http://h71000.www7.hp.com/commercial/ada/documentation.html

>> I would think the fact that GNAT also implements it would be
>> a good reason.  DEC Ada is still used on VAX and Alpha, but
>> is not being ported to the Itanium implementation of VMS.
>> No new features are being added, but support is available
>> from HP.
> 
> But the point is that GNAT only implements it for VMS targets, and it  
> doesn't seem that any Ada compiler targetting VMS has much of future.

I thought Robert Dewar had stated they were extending the DEC
features to their other platforms.

>>> GNAT on any other platform (than VMS) uses the GCC way of
>>> inlining machine code, which I am certainly not going to
>>> replicate.
>>
>> I was referring to calling other languages, not inlining.
> 
> Yes, but machine code insertions and parameter passing mechanisms are  
> deeply intertwined. In particular, a (usable) implementation must provide  
> a way to access parameters in a machine code insertion. This is typically  
> done by means of implementation-specific attributes, and I'd be interested  
> in knowing what attributes (and related pragmas) other Ada implementations  
> use, and why.

But my answer was based on VAX/DEC/Compaq/HP Ada, where machine code
insertions are not supported.  One writes (and I have written) an
assembler module and links it to the Ada modules.  I don't have
an understanding of the fascination with machine code insertions
on other operating systems.