Re: Specifying parameter passing convention and place (register)

[Kilgallen@SpamCop.net (Larry Kilgallen)]

In article <opsascnzjtp4pfvb@bram-2>, "Nick Roberts" <nick.roberts@acm.org> writes:
> On 7 Jul 2004 13:54:01 -0500, Larry Kilgallen <Kilgallen@SpamCop.net>  
> wrote:

>> but if you want the following shortcut it is somewhat weirdly
>> named:
>>
>> 	http://h71000.www7.hp.com/commercial/ada/documentation.html
> 
> Well that weird link redirects me to another page, which, believe it or  
> not, is practically the /second/ place I looked! Unfortunately, although  
> this page has links to various bits of Ada documentation, none of that  
> documentation has the information I need. I have looked in the LRM listed  
> there (a PDF file), which lists the implementation-specific pragmas and  
> attributes, but there are neither any pragmas nor any attributes relating  
> to parameter passing mechanisms.

Did you look in section 13.9a of that document ?
In particular, look for the word MECHANISM.

> Do I take it DEC Ada doesn't, in fact, have any such pragmas or attributes?
> 
>> I thought Robert Dewar had stated they were extending the DEC
>> features to their other platforms.
> 
> I don't know, but it doesn't sound very likely that mechanisms relating to  
> VAX/VMS or Alpha/VMS (or VAX/Unix) will be very transferable to other  
> architectures/environments.

Certainly the mechanisms VALUE and REFERENCE are of general use.

The mechanism DESCRIPTOR is only for where a large variety of string
representations are supported on the operating system.  For environments
where data passed between languages will never include bounded strings,
bit strings, non-contiguous arrays, then defaulting to your local form
of DESCRIPTOR for a string starting at offset 1 is adequate.

You could add a mechanism called REGISTER, and if GNAT does this
machine code insertion, I am surprised ACT has not added such a
mechanism.