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Re: Does CPython already has Peephole optimizations?

From Ned Batchelder <ned@nedbatchelder.com>
Subject Re: Does CPython already has Peephole optimizations?
Date 2014-02-17 07:48 -0500
References <mailman.7086.1392625473.18130.python-list@python.org> <5301cf82$0$29985$c3e8da3$5496439d@news.astraweb.com>
Newsgroups comp.lang.python
Message-ID <mailman.7092.1392641296.18130.python-list@python.org> (permalink)

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On 2/17/14 3:59 AM, Steven D'Aprano wrote:
> On Mon, 17 Feb 2014 13:54:25 +0530, Laxmikant Chitare wrote:
>
>> I read about this article:
>> http://www.python.org/workshops/1998-11/proceedings/papers/montanaro/
> montanaro.html
>>
>> Just wanted to clarify whether CPython already includes these kind of
>> byte code optimizations? Are all the temporary variables removed when
>> byte code is generated?
>
>
> You can check these things for yourself:
>
> import dis
> dis.dis(function)
>
>
> will show you the byte code.
>
> But in general, I would expect not. CPython (that's the Python you
> probably use) doesn't do a lot of optimization apart from some simple
> constant folding. If you're interested in optimizing Python, you should
> look at the JIT optimizing Python compiler, PyPy.
>
>

CPython does some constant folding, and also jump optimizations.  In my 
role as coverage.py maintainer, I would love to see a way to disable all 
those optimizations.  I tried filing a bug about it 
(http://bugs.python.org/issue2506), but it did not win the popular 
support I had hoped for.

-- 
Ned Batchelder, http://nedbatchelder.com

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Thread

Does CPython already has Peephole optimizations? Laxmikant Chitare <laxmikant.general@gmail.com> - 2014-02-17 13:54 +0530
  Re: Does CPython already has Peephole optimizations? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-17 08:59 +0000
    Re: Does CPython already has Peephole optimizations? Ned Batchelder <ned@nedbatchelder.com> - 2014-02-17 07:48 -0500
    Re: Does CPython already has Peephole optimizations? Terry Reedy <tjreedy@udel.edu> - 2014-02-17 08:51 -0500
    Re: Does CPython already has Peephole optimizations? Laxmikant Chitare <laxmikant.general@gmail.com> - 2014-02-18 10:41 +0530

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