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Re: "i = i|0"

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Christoph Michael Becker wrote:

> Thomas 'PointedEars' Lahn wrote:
>> Christoph Michael Becker wrote:
>>> At least the C semantics are better matched; consider arbitrary input to
>>> the function, or an overflow occuring in the calculation.
>>>
>>> I'm not sure about the performance.  Actually, this idiom is quite
>>> common, so it might cause performance improvements in some ECMAScript
>>> implementations.  At least it is used in asm.js to enforce the type of i
>>> and the return value to be an integer type.
>> 
>> Unfortunately, you are wrong on all accounts.
> 
> Even if I am wrong on all accounts, I wouldn't call that unfortunate--at
> least I could learn from the mistake/misinformation. :)

I would rather that you had not been wrong and this mistake by others had 
been discovered earlier.
 
>> It would appear that at least this Emscripten version (probably asm.js,
>> too) is yet another script-kiddie approach that should be avoided, at
>> least for all computationally critical uses.
> 
> I wouldn't call Emscripten/asm.js a script-kiddie approach.  It seems
> asm.js is already supported by all major browsers, and it seems that
> there are areas of application where asm.js is mandatory for
> performance, e.g. browser games.

So much the worse.
 
>>                                     ToInt32(…) is _not_ equivalent to
>> C/C++’s “int”.
> 
> Of course.  But if I'm not mistaken, there is no ToInt32() involved in
> asm.js code, which instead deals with native "int"s.

You are missing the point.  Native “int”s are *generic*; the “|” algorithm 
is not.  It matters not that asm.js does not use ToInt32(); Emscripten is 
used to transcompile to asm.js, and Emscripten apparently generates code 
that uses ToInt32() implicitly; namely, it uses the “|” operator for 
conversion to pseudo-integer.
 
-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | SVN: <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | ES Matrix: <http://PointedEars.de/es-matrix>
Please do not Cc: me. / Bitte keine Kopien per E-Mail.

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Re: "i = i|0" Christoph Michael Becker <cmbecker69@arcor.de> - 2014-06-12 00:00 +0200
  Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-12 01:04 +0200
    Re: "i = i|0" Christoph Michael Becker <cmbecker69@arcor.de> - 2014-06-12 13:22 +0200
      Re: "i = i|0" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-12 13:35 +0200
        Re: "i = i|0" Christoph Michael Becker <cmbecker69@arcor.de> - 2014-06-12 15:26 +0200

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