Re: 'Superoptimizers' (Nick Maclaren)
Mon, 20 Nov 1995 15:30:29 GMT

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Newsgroups: comp.benchmarks,comp.compilers,comp.arch
From: (Nick Maclaren)
Keywords: optimize
Organization: University of Cambridge, England
References: <47b2fl$> 95-11-080 95-11-141
Date: Mon, 20 Nov 1995 15:30:29 GMT (Bill Leonard) writes:
|> Trouble is, the time taken in most optimizers is not in performing the
|> optimizations, but in looking for the opportunities. ...
|> If someone wants a topic for research, here it is: Come up with a fast (and
|> reliable) predictor of optimizations.

The trouble is that it is a solved problem, and is equivalent to
predicting whether a Turing machine will halt! At best, you can get
it right most of the time.

I would slightly dispute your statement that it is likely that there
are few opportunities for optimisation - it is more usual that there
are huge numbers, but insufficient information to decide which ones
will do good, and which will do harm! But I rather doubt that you
would classify such things as opportunities :-)

Nick Maclaren,
University of Cambridge Computer Laboratory,
New Museums Site, Pembroke Street, Cambridge CB2 3QG, England.
Tel.: +44 1223 334761 Fax: +44 1223 334679

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