[Openmcl-devel] consing iterating through a loop

Cyrus Harmon ch-openmcl at bobobeach.com
Thu Jan 27 01:01:47 UTC 2005


I'm trying to avoid allocating memory as I go through the loop. Here's 
my code and problem:

(flet ((foo ()
		  (declare (optimize (speed 3) (safety 0) (space 0)))
		  (let ((z 2.0d0) (a 0d0))
		    (declare (double-float z)
			     (double-float a))
		    (dotimes  (i 500000)
		      (declare (fixnum i))
		      (setf (the double-float a)
			    (the double-float (+ (the double-float a) (the double-float 
z)))))
		a
	   (time (foo)))


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

In SBCL:

; in: LAMBDA NIL
;     (THE DOUBLE-FLOAT A)
; ==>
;   A
;
; note: doing float to pointer coercion (cost 13) from A
; compilation unit finished
;   printed 1 note

Evaluation took:
   0.002 seconds of real time
   0.0 seconds of user run time
   0.0 seconds of system run time
   0 page faults and
   96 bytes consed.
1000000.0d0

Any easy way to fix this?

Thanks,

Cyrus






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