Re: Pass by reference

[Martin Krischik <krischik@users.sourceforge.net>]

Dan McLeran wrote:

>> Good Ada compiler will do what is best. So "array (1 .. 2) of Character"
>> is likely to be passed by value while "array (1 .. 10_000) of Integer" is
>> probably passed by reference. And some Ada compilers might even use pass
>> by register.
> 
> Not sure what you mean by 'pass by register'. Maybe each value of a
> 2-element array are loaded into registers and then read by the calling
> function?

Well on a 32bit CPU any data with 'Size <= 32 can be passed by register. But
this is purly academic since AFAIK the standart x86 compiler won't do pass
by register anyway. 

>> You say what you need (in, out, in out) and the compiler will choose the
>> optimal way to fullfill you which.
> 
> This is what I want to solidify in my brain. Alot of people posting
> replies seem to say that the compiler has more freedom than the RM
> specifies. If most Ada compilers are conforming, I would assume that
> the compiler only has freedom for unspecified types. By-reference and
> by-values types must be passed as stated in RM 6.2.

True, however there is a reason why By-reference are By-reference. They
yould not be anything else - otherwise dispaching would not work.

With Regards

Martin

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