[Openmcl-devel] consing iterating through a loop

Cyrus Harmon ch-openmcl at bobobeach.com
Thu Jan 27 17:23:08 UTC 2005


Randy et al.,

This is, of course, very cool, but I'd like to point out that other 
implementations such as SBCL (SBCL on PPC) don't cons on this example. 
Clearly different compilers have strengths and weaknesses and OpenMCL 
is great at a lot of things. While use fpc-ppc is a reasonable answer, 
two other alternatives come to mind. First, I'm by no means an expert 
in lisp compiler declarations, so it seemed reasonable that there might 
be something I was forgetting here that would keep OpenMCL from 
consing. Second, assuming all the declare options are correct, is there 
anything that can be done in the compiler to fix this? I know Gary 
Byers has better things to do than explain compiler internals to folks 
like me all day, but if anyone knows why we're consing here, I'd love 
to hear the answer.

Thanks,

Cyrus


On Jan 27, 2005, at 5:37 AM, Randall Beer wrote:

> Cyrus,
>
> This is pretty much the kind of thing that FPC-PPC 
> (http://vorlon.cwru.edu/~beer/index.html#software) was written for:
>
> ? (flet ((foo ()
>             (declare (optimize (speed 3) (safety 0) (space 0)))
>             (let ((z 2.0d0))
>               (WITH-TEMP-DOUBLE-FLOATS (a)
>                 (dotimes  (i 500000)
>                   (declare (fixnum i))
>                   (%SET-DOUBLE! a (+ a z)))
>                 (%COPY-FLOAT a)))))
>        (time (foo)))
>
> (FOO) took 16 milliseconds (0.016 seconds) to run.
> Of that, 20 milliseconds (0.020 seconds) were spent in user mode
>          0 milliseconds (0.000 seconds) were spent in system mode
>  16 bytes of memory allocated.
> 1000000.0D0
>
> Randy
>
>
> On Jan 26, 2005, at 8:01 PM, Cyrus Harmon wrote:
>
>> In OpenMCL:
>>
>> (FOO) took 760 milliseconds (0.760 seconds) to run.
>> Of that, 150 milliseconds (0.150 seconds) were spent in user mode
>>          50 milliseconds (0.050 seconds) were spent in system mode
>>          560 milliseconds (0.560 seconds) were spent executing other 
>> OS processes.
>> 361 milliseconds (0.361 seconds) was spent in GC.
>>  8,000,000 bytes of memory allocated.
>>
>> 1000000.0D0
>




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