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Re: "i = i|0"

Cross-posted to 2 groups.

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On 06/11/2014 05:09 PM, Ike Naar wrote:
> On 2014-06-11, Stefan Ram <ram@zedat.fu-berlin.de> wrote:
>>   When they then call the function with non-integer arguments
>>   its their fault. (Or they can write a |0 wrapper instead
>>   of requiring each and every function to do |0 and thereby
>>   possibly slowing down execution and enlarging code size.)
> 
> With a decent optimizing compiler, do you think that |0 would
> slow down execution or enlarge code size?

I'm no JS experts, but so far I haven't seen any responses from those
who are, so I'll throw in my guesses.

It seems reasonable to me that it would - in javascript, |0 doesn't just
cause the integer value to be unchanged (something a smart compiler
could drop) - it also (and first) causes conversion to a 32-bit integer
type, if necessary. The compiler can't be expected to know that such a
conversion will not, in fact, be necessary. This is a substantial
difference from the original C code, where such conversions would occur,
if necessary, in the calling code, where the compiler can be sure. A JS
compiler would have to generate code to check the type of the argument,
and code to perform the conversion. The checking part, at least, will
have to be executed even though the conversion code will not.

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Re: "i = i|0" Ike Naar <ike@iceland.freeshell.org> - 2014-06-11 21:09 +0000
  Re: "i = i|0" James Kuyper <jameskuyper@verizon.net> - 2014-06-11 17:37 -0400
    Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-12 00:56 +0200
      Re: "i = i|0" raltbos@xs4all.nl (Richard Bos) - 2014-06-12 11:41 +0000
        Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-12 14:28 +0200
      Re: "i = i|0" James Kuyper <jameskuyper@verizon.net> - 2014-06-12 08:19 -0400
        Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-12 14:45 +0200
          Re: "i = i|0" James Kuyper <jameskuyper@verizon.net> - 2014-06-12 09:25 -0400
            Re: "i = i|0" raltbos@xs4all.nl (Richard Bos) - 2014-06-12 14:50 +0000
              Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-12 16:55 +0200
                Re: "i = i|0" Keith Thompson <kst-u@mib.org> - 2014-06-12 11:28 -0700
                Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-12 20:46 +0200
                Re: "i = i|0" Christoph Michael Becker <cmbecker69@arcor.de> - 2014-06-12 20:58 +0200
                Re: "i = i|0" Kaz Kylheku <kaz@kylheku.com> - 2014-06-12 19:20 +0000
                Re: "i = i|0" Christoph Michael Becker <cmbecker69@arcor.de> - 2014-06-12 22:13 +0200
                Re: "i = i|0" Kaz Kylheku <kaz@kylheku.com> - 2014-06-12 21:15 +0000
                Re: "i = i|0" Christoph Michael Becker <cmbecker69@arcor.de> - 2014-06-12 23:59 +0200
                Re: "i = i|0" Christoph Michael Becker <cmbecker69@arcor.de> - 2014-06-13 01:10 +0200
                Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-13 01:52 +0200
                ECMAScript standards (was: "i = i|0") Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-15 12:53 +0200
                Re: "i = i|0" Stephen Sprunk <stephen@sprunk.org> - 2014-06-12 17:11 -0500
                Re: "i = i|0" Denis McMahon <denismfmcmahon@gmail.com> - 2014-06-12 22:40 +0000
                Re: "i = i|0" glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-06-12 22:44 +0000
                Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-13 01:16 +0200
                Re: "i = i|0" raltbos@xs4all.nl (Richard Bos) - 2014-06-16 12:55 +0000
                Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-16 22:44 +0200
                Re: "i = i|0" Thomas Richter <thor@math.tu-berlin.de> - 2014-06-13 19:16 +0200
                Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-13 19:21 +0200
                Re: "i = i|0" Tim Streater <timstreater@greenbee.net> - 2014-06-13 18:24 +0100
                Re: "i = i|0" Kaz Kylheku <kaz@kylheku.com> - 2014-06-13 21:25 +0000
            Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-12 17:13 +0200
              Re: "i = i|0" raltbos@xs4all.nl (Richard Bos) - 2014-06-12 15:20 +0000
                Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-12 17:32 +0200
                Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-17 12:30 +0200
              Re: "i = i|0" James Kuyper <jameskuyper@verizon.net> - 2014-06-12 12:17 -0400
                Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-12 20:01 +0200
                Re: "i = i|0" James Kuyper <jameskuyper@verizon.net> - 2014-06-12 16:13 -0400
                Re: "i = i|0" glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-06-12 20:44 +0000
                Re: "i = i|0" Kaz Kylheku <kaz@kylheku.com> - 2014-06-12 20:59 +0000
                Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-13 01:22 +0200
                Re: "i = i|0" Martin Shobe <martin.shobe@yahoo.com> - 2014-06-12 19:48 -0500
                Re: "i = i|0" "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2014-06-12 18:32 -0700
                Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-13 12:12 +0200
                Re: "i = i|0" John Harris <niam@jghnorth.org.uk.invalid> - 2014-06-13 10:16 +0100
                Re: "i = i|0" Tim Streater <timstreater@greenbee.net> - 2014-06-13 11:44 +0100
          Re: "i = i|0" "BartC" <bc@freeuk.com> - 2014-06-12 15:06 +0100
            Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-12 16:54 +0200

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