How to make Lisp go faster than C [pdf]

http://www.iaeng.org/IJCS/issues_v32/issue_4/IJCS_32_4_19.pdf

by jgg • 16 years ago

27 15 16 years ago

iaeng.org

martincmartin2• 16 years ago

gcc 4.0.3 vs. CMUCL, the predecessor to SBCL.

Avshalom• 16 years ago

To those who know the SBCL compiler better:

The paper says that to get the speed they had to turn off run time type checking, but they say "here's how to do it globally" does that mean you can turn of type checking in just one module or function?

martincmartin2• 16 years ago

Yes. The Common Lisp spec says you can put declarations a lot of places, including prog:

http://clhs.lisp.se/Body/s_declar.htm

So you can basically wrap it around any S-expression you want.

When I was at ITA we did that a lot. For example, there was a macro i+ that would expand to basically "the two arguments are fixnums, as is the result. Now, please give me the sum."

In debug builds, the type declarations would be come assertions. In release builds, they'd become assumptions, i.e. the whole thing would compile to a single x64 ADD instruction.

lispm• 16 years ago

Common Lisp allows you to wrap declarations around forms. Use LOCALLY for that.

VMG2• 16 years ago

barely readable

jgg3• 16 years ago

What do you mean? Is it the layout, the content or something else? I was able to read it just fine.

j_baker2• 16 years ago

The scribd version is pretty bad.

twobar• 16 years ago

The scribd version is nearly unreadable, but the pdf is fine.

VMG2• 16 years ago

the scribd version and Gnomes epdfviewer had terrible resolution, so I assumed it was a scanned document.

Evince displays it correctly.

The scribd version seems to be terrible for everybody though

greglindahl• 16 years ago

This is typical for papers like this: take a toy algorithm, show it's kinda as fast as C/Fortran if you do something really odd, then declare victory. This works better if your C compiler lacks important optimizations, like a loop nest optimizer.

If you really want to impress people, take a significant algorithm, preferably one of the SPECcpu benchmarks, write the whole thing in Lisp, and then see what happens.

nearestneighbor• 16 years ago

It's not just Lisp. Language advocates are the snake oil salesmen among computer scientists. Case in point: http://www.reddit.com/r/programming/comments/bnnoh/fast_auto...

jgg3• 16 years ago

>It's not just Lisp. Language advocates are the snake oil salesmen among computer scientists.

It's true. (-: I submitted the paper mostly because it's a condensed "how-to" for optimizing Common Lisp code. I think the name of the paper itself is really, really sketchy.

j_baker2• 16 years ago

I admit to not having read the paper all the way through, but Figure 2 only shows Common Lisp as being noticeably faster than C in one instance, and I suspect that's due to an anomaly of some kind (it's totally out of line with the other C speeds).

_cbsz• 16 years ago

Why is the scribd version 1) ugly and 2) in Flash? I thought they were all HTML 5 these days, and I'd clicked the scribd link to give them another chance.

How to make Lisp go faster than C [pdf]

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