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From: falis@ma.aonix.com (Ed Falis)
Subject: Re: Compiler for Z80/6510
Date: 1999/11/26
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Date: 1999-11-26T00:00:00+00:00
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On Thu, 25 Nov 1999 23:38:20 GMT, Peter Milliken <peter.milliken@australia.boeing.com> wrote:

> Would you care to comment then on the paper written by Lawlis and Elam
> which was published in Tri-Ada '92 titled "Ada Outperforms Assembly: A
> Case Study" where, in point 6, they draw conclusions such as: compiler
> optimisation has reached such a state of the art that it can implement
> "hundreds of heuristics from a library of knowledge in this area of
> technology" and generate code which can "beat assembly code in both size
> and performance"?
> 
> I am curious, on the one hand we have this paper (advertised in the Ada
> Home page) and on the other hand, experienced compiler writers such as
> yourself. These statements seem to contradict each other. I do not have
> any experience in compiler writing but I have been prepared to accept
> the paper at it's face value (having no way to confirm or deny :-)). Did
> Lawlis and Elam get it wrong? Were they correct for their particular
> circumstances and environment? I have shown the paper to non Ada
> software engineers and received various responses, the worst being open
> ridicule and statements that the paper must be a pure fabrication.
> 
> Thanks
> Peter

My take on it, having been involved in Ada compilers for a long time, is
that an optimizing compiler can do well compared to the average programmer,
turned to assembly language.  But, a good assembly programmer for a given
architecture can do better.  This isn't rocket science - human intelligence generally
beats what we can simulate with machines.

- Ed