Re: Where is the elusive jump command?

[gisle@apal.ii.uib.no (Gisle S�lensminde)]

In article <38E3CDF4.CF5450E2@Raytheon.com>, Samuel T. Harris wrote:
>Dan Nagle wrote:
>> 
>> Hello,
>> 
>> >>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<
>> 
>> On 3/30/00, 1:03:19 PM, "Marin D. Condic"
>> <mcondic-nospam@quadruscorp.com> wrote regarding Re: Where is the
>> elusive jump command?:
>> 
>> 
>> Does Ada have any loop, branch or assignment statements, which, by
>> definition,
>> may be executed in parallel?  My reading and exercises haven't shown
>> them to me yet.  Maybe I just haven't gotten to the right chapter...
>
>Parallelization of language constructs is a function of the compiler.
>If a compiler is written for a high end parallel machine, then I
>expect it to produce parallel code for the basic stuff. Such a question
>might become a compiler requirement in the selection process.

And typically the available parallelizing compilers have been fortran
compilers, due to demand from those using these parallel machines.

>
>In any event, Ada provides parallel constructs both in the forms
>of tasks as well as the distributed systems annex. Both are powerful
>forms with standardized semantics upon which you can rely.
>I can produce parallel algorithms using tasks. If my compiler does
>not parallelize record assignments, then I can use tasks to
>parallelize the operation (at least logically). Of course, the
>degree to which a compiler takes advantage of multiple processors
>is also an implementation dependent issue, but you are more likely
>to score positive results across vendors on this question
>than with basic operations such as assignment.
>
>Since Ada already incorporates parallel constructs in the form
>of tasks and partitions, perhaps a later generation Ada will
>include keywords or pragmas which enable parallel operations
>on more basic syntactic structures like assignment.

Much of the parallel code written in fortran and C uses libraries
like MPI. These can be interfaced from Ada. Some machines can also
use tasking/multithreading for parallel programs, and in this case
Ada may be more easy to use than fortran/C. 

One of the good things with F90 is the array semantics where you
can do arithmetric operations on 2-dimensional arrays, and the
SIMD constructs. The array-syntax can be implemeted through 
operator overloading, but I have not seen any widely used libraries
in Ada doing this, but I have not looked too hard, since I no 
longer do numeric programming.

-- 
--
Gisle S�lensminde ( gisle@ii.uib.no )   

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