From 6801592419014289525 X-Google-Thread: f78e5,52112cea9d2ccd4a X-Google-Attributes: gidf78e5,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news2.google.com!news.maxwell.syr.edu!news.tele.dk!news.tele.dk!small.news.tele.dk!newsfeed.icl.net!newsfeed.fjserv.net!peer-uk.news.demon.net!kibo.news.demon.net!mutlu.news.demon.net!news.demon.co.uk!demon!stump.algebra.com!devnull From: squell@alumina.nl (Marc Schoolderman) Newsgroups: comp.std.c++ Subject: Re: =?ISO-8859-1?Q?=A75=2E2=2E2/8_unspecified_evluation_od?= =?ISO-8859-1?Q?er=3F?= Date: Mon, 25 Jul 2005 19:06:16 GMT Lines: 39 Sender: mail2news@demon.net Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: <42E4EB01.9020700@alumina.nl> References: NNTP-Posting-Host: news.news.demon.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Trace: news.demon.co.uk 1122318381 22104 158.152.254.254 (25 Jul 2005 19:06:21 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Mon, 25 Jul 2005 19:06:21 +0000 (UTC) X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) X-User-Agent: Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.7.6) Gecko/20050319 X-Accept-Language: en-us, en X-Virus-Scanned: amavisd-new at cs.mu.OZ.AU X-Received: (from fjh@localhost) by mulga.cs.mu.OZ.AU (8.12.10+Sun/8.12.9/Submit) id j6PJ6GfT001982; Tue, 26 Jul 2005 05:06:16 +1000 (EST) X-Path: comp-std-cpp-robomod!not-for-mail X-Delivered-To: std-c++@ucar.edu X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f X-Newsgroups: comp.std.c++ Xref: g2news1.google.com comp.std.c++:1476 Steven T. Hatton wrote: > Do compilers really take advantage of this flexibility? How much does it > buy? Has the theoretical problem actually manifested itself in production > code? Would specifying order on the evaluation of function arguments > impose great hardship on implementers? Would it adversely impact execution > speed, compile time, or code size? How much? An equally important question is, "What would it gain?". This is not a theoretical problem, it has a lot to do with calling conventions. The basic model is that on a function call, a compiler pushes all its arguments on a stack. Which means there are two main ways to do this, left-to-right, or right-to-left. This choice is not arbitrary. Most C/C++ implementations will probably push right-to-left, so that the first argument will always be at a fixed distance from the stack top. However, other languages/systems will have different calling conventions, and implementations usually offer special specifiers to adjust to them (_pascal, _cdecl, _fastcall, _stdcall, etc.) If C++ mandated an evaluation order, this means inefficiency for calling conventions which don't match it, just so that 5 people will get their degenerate code to work. ~Marc. --- [ 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://www.jamesd.demon.co.uk/csc/faq.html ]