Re: Numerical code efficiency

Thanks, that's exactly the sort of information that I was looking for. I 
hadn't gotten around to trying fixnums in Corman Lisp. I'll definitely try 
out some other implementations.

I poked around a bit in the source code but didn't figure out where the 
compile decides whether or not to inline math operations. I might look at 
this a bit more at some point. The fact that Corman Lisp comes with all the 
source code, and the attractive price for a commercial development license, 
continues to hold my interest in this implementation.


At 05:59 PM 10/12/2003, you wrote:
>As far as I know Corman Lisp has not invested any significant
>effort in optimizing floating point computations.
>
>The person writing the original note is making a mistake, IMHO, in
>using Corman Lisp to test the performance of 'Lisp' wrt floating
>point.
>
>If you want to see what an optimizing Lisp compiler can do with
>floating
>point then you should download the free version of Allegro 6.2 Franz
>Common Lisp and try your various optimizations and timing tests.
>
>On Windows, at least, if you disassemble optimized code, you will
>see native floating point instructions for floating point ops that, I
>would
>guess, compare reasonably with that generated for equivalent C code.
>
>(This is not meant to be a commerical plug for Franz or anything like
>that.
>Just the facts, maam.  I have examined the disassembled output of
>floating point code I have tried to optimize using various Lisp
>compilers,
>including Franz, Corman and Lispworks.  Franz is the only output
>that
>looks to my eye (unlearned as it is in Intel assembler) to generate
>efficient native instructions).
>
>
> >>> [email protected] 10/13/03 08:22AM >>>
>On Sun, 12 Oct 2003 11:17:21 -0400, "Dan Muller"
><[email protected]> said:
> > 2. Looking at the disassembled functions, i noticed that svref
>results
> >    in an actual function call, as does the call to #'+. Is there
>any
> >    way around this? Declaiming these inline doesn't work; I get a
> >    warning that the source isn't accessible.
>
>It looks like there is no inlining of #'+ for floats. The following
>inlines correctly for fixnums for example:
>
>(defun test (a b)
>     (declare (optimize (speed 3) (safety 0))
>              (type fixnum a)
>              (type fixnum b))
>     (the fixnum (+ a b)))
>
>But the following doesn't for floats:
>
>(defun test (a b)
>     (declare (optimize (speed 3) (safety 0))
>              (type double-float a)
>              (type double-float b))
>     (the double-float (+ a b)))
>
>As for whether it's typical for Lisp compilers, I don't know. CMUCL
>(which is well known for its optmisation abilities) will inline the
>second example.
>
>Chris.
>--
>   Chris Double
>   [email protected]
>
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Dan Muller
[email protected]

Some people believe in absolutes. Others aren't so sure.



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