Just how fast is LISP?

pschmidt@convex.com (Perry Schmidt)
Wed, 20 Nov 1991 15:02:45 GMT

          From comp.compilers

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Re: Just how fast is LISP? schwartz@roke.cs.psu.edu (1991-11-20)
Re: Just how fast is LISP? barmar@think.com (1991-11-21)
Re: Just how fast is LISP? ressler@cs.cornell.edu (1991-11-21)
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[4 later articles]
| List of all articles for this month |

Newsgroups: comp.compilers
From: pschmidt@convex.com (Perry Schmidt)
Keywords: design, Lisp, performance
Organization: CONVEX Computer Corporation, Richardson, Tx., USA
References: 91-11-072
Date: Wed, 20 Nov 1991 15:02:45 GMT

Comment and question about...

>Clearly this poster is not aware of much of the research of the past decade
>in the Lisp world. Most Lisp systems are compiled nowadays, achieving
>speeds close to that of traditional languages. I measured some benchmarks
>recently on the current T compiler (described in a SIGPLAN'86 paper by Kranz
>et al., incidentally) and the Allegro Common Lisp compiler, and for "normal"
>dynamically-typed Lisp code, these systems were running within a factor of 5
>(10 for the worst offenders) of optimized C. After hand-tuning, adding type
>declarations, turning on the optimizers full-blast, turning off safety,
>sacrificing overflow checking, etc., I got these benchmarks to run close to
>half the speed of optimized C. ...

Comment: I will agree LISP is MUCH faster than it use to be. And for many
applications LISP can now be used where before it "couldn't" because it
was still too slow. But I do not agree that LISP is as fast as Opt. C
compilers of today. I've heard this claim many times, but I've never seen
any evidence of this - only claims[** See Note]. Even in the above, you
got substancial speedup from the LISP program, and came close to the C
program. But what would happen if you started to do a lot of that same
hand-tuning for the C program?? And I also submit that these are your
BEST LISP compiles compared to your Avg. to better than avg. C compilers,
not your BEST C compilers. That's not to take away from new LISP
compilers - they ARE good, and do generate fast code, but not as fast as
your other "procedural" language compilers.

[**Note: I can't find the source for the quote, but I remember reading
some AI book claiming that LISP is as fast or faster than traditional
prog. langs. in math intensive programs. Granted this is an extreme claim
but I was still amused by this, especially since most of your REAL math
intensive programs are still Fortran b/c they are the compilers that
generate the fastest code when comparing the best compilers. That doesn't
mean I'd want to program in Fortran though... And b/f any flames come
this way, I'd be the first to say this is market driven more than
anything, but it IS still a fairly widely accepted fact.]

Question: As I said, I've seen many claims about LISP being as fast as C.
Got any proof? I sure would like to see some numbers on these claims.
Can anyone direct me to some of these? (And of course after seeing some
of these, I just may eat some of my words above...)

Perry Schmidt

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