From 8585817563025812174 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,7522e5259f7267d6 X-Google-Attributes: gidf78e5,public From: Anthony DeRobertis Subject: Re: x = y = z; Undefined? Date: 2000/01/10 Message-ID: #1/1 X-Deja-AN: 570489557 Content-Transfer-Encoding: 7bit Approved: Fergus Henderson , moderator of comp.std.c++ References: <3876254a.30903561@news.csrlink.net> X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f Content-Type: text/plain; charset=ISO-8859-1 X-Complaints-To: abuse@demon.net X-Mail2News-Path: news.demon.net!mulga.cs.mu.oz.au X-Trace: mail2news.demon.co.uk 947453350 mail2news:27005 mail2news mail2news.demon.co.uk Organization: - X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) User-Agent: MT-NewsWatcher/3.0 (PPC) Mime-Version: 1.0 Nntp-Posting-Date: 9 Jan 2000 06:59:30 GMT Newsgroups: comp.std.c++ In article <3876254a.30903561@news.csrlink.net>, jpotter@falcon.lhup.edu (John Potter) wrote: >could someone give an example of translation which would produce >something other than expected? > > (i1 = i2) += i3; Well, on my PowerPC this would generate (unoptimized): -- sequence point -- or i1,i2,i2 add i1,i1,i3 -- sequence point -- Which could legally be re-arranged: add i1,i1,i3 or i1, i2, i2 Which could then be optimized: or i1, i2, i2 Which means: i1 = i2; As there are no sequencing points. This could concievably be done for scheduling purposes. I don't seem to be able to get my compile to do it (it does even weirder stuff...) -- Windows 95 (win-DOH-z), n. A thirty-two bit extension and graphical shell to a sixteen bit patch to an eight bit operating system originally coded for a four bit microprocessor which was used in a PC built by a formerly two bit company that couldn't stand one bit of competition. --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://reality.sgi.com/austern_mti/std-c++/faq.html ]