[Sbcl-devel] SB-EXT:FLOAT-NAN-P and SB-EXT:FLOAT-INFINITY-P boxing

[JTK <je...@gm...>]

Hello,

I was trying to write a cross-implementation package  to handle NaNs and INFs 
and was a little bit surprised to see that FLOAT-NAN-P and FLOAT-INFINITY-P don't inline for double
floats (or they perform boxing despite being inlined).   Is there a way to make them not box?   

One could do tricks like the fact that NaNs fail (= x x), but this seems wrong, and I couldn't find a reliable
trick for infinity.  [maybe (or (> x most-positive-double-float) (< x most-negative-double-float)) ]

Both functions are proclaimed MAYBE-INLINE.   

Many thanks,
- Jan

Example  in SBCL 1.2.5


 (time
  (locally (declare (optimize speed))
    (loop for i from 1 to 10000000
          for x of-type double-float = (float i 1d0)
          when (sb-ext:float-nan-p x)
          do (print :found-a-nan))))

Evaluation took:
  0.102 seconds of real time
  0.102024 seconds of total run time (0.101510 user, 0.000514 system)
  100.00% CPU
  270,833,595 processor cycles
  159,973,376 bytes consed  [10M x 8 bytes x 2, so float seems to be boxed]
  
------

(time
  (locally (declare (optimize speed))
  (loop for i from 1 to 10000000
       for x of-type single-float = (float i 1e0)
	when (sb-ext:float-nan-p x)
	 do (print :found-a-nan))))

Evaluation took:
  0.073 seconds of real time
  0.073307 seconds of total run time (0.073186 user, 0.000121 system)
  100.00% CPU
  194,769,260 processor cycles
  0 bytes consed
  

-----
(time
(locally (declare (optimize speed))
 (loop for i from 1 to 10000000
       for x of-type double-float = (float i 1d0)
       when (= (sin x)  0.923423423423423d0)
       do (print :found-a-sin))))

Evaluation took:
  0.268 seconds of real time
  0.269283 seconds of total run time (0.268557 user, 0.000726 system)
  100.37% CPU
  713,729,790 processor cycles
  0 bytes consed