Path: csiph.com!usenet.pasdenom.info!aioe.org!news.stack.nl!newsfeed.xs4all.nl!newsfeed1a.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.001 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'python,': 0.02; 'cpython': 0.05; 'filing': 0.07; 'variables': 0.07; 'optimizing': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'subject:Does': 0.09; 'python': 0.11; 'bug': 0.12; 'article:': 0.16; 'folding.': 0.16; 'pypy.': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'subject:already': 0.16; 'wrote:': 0.18; 'code.': 0.18; 'feb': 0.22; 'import': 0.22; 'header:User-Agent:1': 0.23; 'byte': 0.24; 'received:comcast.net': 0.24; 'mon,': 0.24; 'header:X-Complaints-To:1': 0.27; 'header:In- Reply-To:1': 0.27; 'tried': 0.27; 'url:bugs': 0.29; 'am,': 0.29; "doesn't": 0.30; 'code': 0.31; 'constant': 0.31; "d'aprano": 0.31; 'disable': 0.31; 'steven': 0.31; 'probably': 0.32; 'url:python': 0.33; 'not.': 0.33; 'role': 0.34; 'but': 0.35; 'subject:?': 0.36; 'url:org': 0.36; 'should': 0.36; 'to:addr:python-list': 0.38; 'expect': 0.39; 'does': 0.39; 'to:addr:python.org': 0.39; 'received:org': 0.40; 'read': 0.60; 'simple': 0.61; "you're": 0.61; 'show': 0.63; 'kind': 0.63; 'love': 0.65; 'temporary': 0.65; 'apart': 0.72; 'subject:skip:o 10': 0.84 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Ned Batchelder Subject: Re: Does CPython already has Peephole optimizations? Date: Mon, 17 Feb 2014 07:48:00 -0500 References: <5301cf82$0$29985$c3e8da3$5496439d@news.astraweb.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: c-50-133-228-126.hsd1.ma.comcast.net User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 In-Reply-To: <5301cf82$0$29985$c3e8da3$5496439d@news.astraweb.com> X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 36 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1392641296 news.xs4all.nl 2943 [2001:888:2000:d::a6]:50728 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:66600 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