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From: Robert Dewar <robert_dewar@my-deja.com>
Subject: Re: GNAT & GCC performace (bad news)
Date: 1999/12/07
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 <38473D90.68D8F47@acenet.com.au> <1999Dec3.103807.1@eisner>
 <82fgh2$mt3$1@nnrp1.deja.com> <1999Dec6.073729.1@eisner>
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Date: 1999-12-07T00:00:00+00:00
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In article <1999Dec6.073729.1@eisner>,
  Kilgallen@eisner.decus.org.nospam wrote:
> On a theoretical basis, it is possible to do anything in
> machine language one can do in a higher level language.
> However I believe that optimizing for various versions of
> a particular chip is higher priority for the folks pushing
> that chip than they are for the folks trying to provide a
> multi-platform compiler (regardless of whether it emits
> assembly language or C code).


Nevertheless there are fundamental problems in going through C.
For example, one cannot expect a wonderful optimizing C compiler
to do much in Ada critical areas like overflow detection and
exception handling etc.

The point though is that compilers, which generate assembler
or machine language, are very different beasts from translators
which translate from one high level language to another. In
practice there is almost always a loss from the translator
approach, often significant.

You quote theory, but I am talking from 30 years of experience
in compilers, I have NEVER seen a case where language to
language translation did not lose efficiency compared to direct
compilation.

Feel free to quote a counter example, but theorizing is not
convincing!


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