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- From: davidm@questor.rational.com (David Moore)
- Newsgroups: comp.compilers
- Subject: Re: Code quality
- Keywords: optimize, comment
- Message-ID: <93-01-020@comp.compilers>
- Date: 6 Jan 93 19:24:21 GMT
- Article-I.D.: comp.93-01-020
- References: <93-01-017@comp.compilers>
- Sender: compilers-sender@iecc.cambridge.ma.us
- Reply-To: davidm@questor.rational.com (David Moore)
- Organization: Rational
- Lines: 23
- Approved: compilers@iecc.cambridge.ma.us
-
- drw@zermelo.mit.edu (Dale R. Worley) writes:
-
- >How important is generated code quality these days? There are a lot of
- >good optimization techniques that seem to be adequate for ordinary
- >programming. But they still are at least 10% or 20% worse than the ideal.
- >Is there much of a market for another 10% in speed of generated code?
-
- It seems to me that compile time is roughly exponential in the deficiency
- of the generated code. So, to produce code that is 10% worse than optimal
- takes twice as long as it does to produce code 20% less than optimal (if
- your compiler is optimizer-bound). I suspect that programmer time required
- to get the optimizer solid is also exponential.
-
- So getting that last few percent requires a lot of resources.
-
- Perhaps someone has collected some numbers on this? I am just making the
- statement based on a gut feeling gotten from writing an optimizer.
- [It varies all over the place. The Princeton/Bell Labs lcc compiler
- is supposed to produce better code faster than GCC. Ken Thompson's Plan 9
- compiler is supposed to be better still in both dimensions. -John]
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