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From: Robert A Duff <bobduff@shell01.TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: Lack of formal syntax undermines Ada
Date: Sat, 12 Apr 2008 21:16:25 -0400
Organization: The World Public Access UNIX, Brookline, MA
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Date: 2008-04-12T21:16:25-04:00
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Gary Scott <garylscott@sbcglobal.net> writes:

> In some languages that have pure functions, the compiler is free to not
> execute the function call if it can determine the return value by other
> means and so eliminate the code entirely (nor inline it).  I was
> thinking thinking there might be situations where a C procedure call
> might be optimized away based upon assumptions of purity
> (pureness?).

Well, normally an Ada compiler/optimizer is not supposed to assume
things that are not true.  There are some exceptions -- for example,
if you suppress run-time checks, and divide by X, and X=0, the compiler
can (and should!) assume that X is not 0.

If a pragma Pure applies to a function, then you had better beware if
that function is written in C!  But normally, the compiler cannot assume
that any function is pure, unless it can prove it to be true.

>... Probably an outdated question based upon recent posts.

OK.  ;-)

- Bob