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List:       sbcl-devel
Subject:    [Sbcl-devel] Issue Fresh in SBCL 1.1.8: SSE Intrinsics!
From:       Lynn Quam <quam () AI ! SRI ! COM>
Date:       2016-04-28 14:14:52
Message-ID: 57221ADC.8000002 () ai ! sri ! com
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[Attachment #2 (multipart/alternative)]


When experimenting with the code in 
http://www.pvk.ca/Blog/2013/06/05/fresh-in-sbcl-1-dot-1-8-sse-intrinsics 
I experienced problems with "arithmetic error FLOATING-POINT-OVERFLOW 
signalled".    After studying the code for a while I determined that the 
code must be run with floating traps disabled, as shown below, and the 
return results are then correct.   Paul Khuong's blog article doesn't 
mention this.

(sb-int:with-float-traps-masked (:OVERFLOW :INVALID)
   (mandelbrot-escape (%make-simd-pack-single 1.0 -1.0 3.0 0.0)
              (replicate-float 0.0)
              256))
1 256 0 256



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<html>
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    <meta http-equiv="content-type" content="text/html; charset=utf-8">
  </head>
  <body text="#000000" bgcolor="#FFFFFF">
    When experimenting with the code in <font face="Helvetica"><a \
class="moz-txt-link-freetext" \
href="http://www.pvk.ca/Blog/2013/06/05/fresh-in-sbcl-1-dot-1-8-sse-intrinsics">http://www.pvk.ca/Blog/2013/06/05/fresh-in-sbcl-1-dot-1-8-sse-intrinsics</a> \
  I experienced problems with "arithmetic error
      FLOATING-POINT-OVERFLOW signalled".       After studying the code for
      a while I determined that the code must be run with floating traps
      disabled, as shown below, and the return results are then
      correct.     Paul Khuong's blog article doesn't mention this.   <br>
      <br>
      (sb-int:with-float-traps-masked (:OVERFLOW :INVALID)<br>
         (mandelbrot-escape (%make-simd-pack-single 1.0 -1.0 3.0 0.0)<br>
                             (replicate-float 0.0)<br>
                             256))<br>
      1 256 0 256<br>
      <br>
      <br>
    </font>
  </body>
</html>



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