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From: William Clodius <wclodius@lanl.gov>
Subject: Re: should I be interested in ada?
Date: 1999/02/19
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Date: 1999-02-19T00:00:00+00:00
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dennison@telepath.com wrote:
> <snip>
> Since Fortran's parallel loops are just loops with extra semantics about what
> dependencies exist between iterations, wouldn't it be possible to do the same
> thing in Ada with new loop pragmas? (eg: prama No_Loop_Carried_Dependencies
> (Loop_Label);) Would such a scheme render the compiler non-conformant?
> <snip>

In essence yes.  The parallel loop forms introduce a context in which,
for example, all input values are those of the variables at the start of
the loop. A variable used as input may in turn depend on the loop, but
that dependence must be treatable as an assignment to a temporary which
is then reassigned to the variable at the end of the loop. This of
course means that a given array element must be modified at most once in
leagal code, but that is not the same as saying it isn't modified at
all, which is what is implied by No_Loop_Carried_Dependencies.
Dependencies are allowed but treated specially.

-- 

William B. Clodius		Phone: (505)-665-9370
Los Alamos Nat. Lab., NIS-2     FAX: (505)-667-3815
PO Box 1663, MS-C323    	Group office: (505)-667-5776
Los Alamos, NM 87545            Email: wclodius@lanl.gov