From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,38fc011071df5a27 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-06-03 12:18:05 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newshosting.com!news-xfer1.atl.newshosting.com!uunet!dca.uu.net!ash.uu.net!nntp.TheWorld.com!not-for-mail From: Robert A Duff Newsgroups: comp.lang.ada Subject: Re: Ideas for Ada 200X Date: 03 Jun 2003 15:18:02 -0400 Organization: The World Public Access UNIX, Brookline, MA Message-ID: References: <6a90b886.0305262344.1d558079@posting.google.com> <3ED41344.7090105@spam.com> <3ED46D81.FF62C34F@0.0> <3ED46E07.4340CABC@0.0> <3ED4F3FD.A0EF7079@alfred-hilscher.de> <6vWcnTWjF83bD0qjXTWcpA@gbronline.com> NNTP-Posting-Host: shell01.theworld.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: pcls4.std.com 1054667882 29479 199.172.62.241 (3 Jun 2003 19:18:02 GMT) X-Complaints-To: abuse@TheWorld.com NNTP-Posting-Date: Tue, 3 Jun 2003 19:18:02 +0000 (UTC) User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 Xref: archiver1.google.com comp.lang.ada:38544 Date: 2003-06-03T15:18:02-04:00 List-Id: Bill Findlay writes: > > Number 6 applies only if there are non-inlined calls involved. > > They presumably don't normally have side effects (because that > > would usually be wrong), but the compiler doesn't *know* that. > > That is, currently the compiler can avoid evaluating X twice in > > "X := X + 1;" only if "X" contains no out-of-line function calls. > > Do volatile variables not come into play in defining eliminable CSEs > (probably not the right language-lawyer language, but YKWIM)? Yes, volatile and atomic come into play. Note that I said, "only if", not "if and only if". In order to do an optimization, the compiler has to prove that it doesn't matter. All kinds of things enter into that proof. > > Number 5 doesn't say anything that 1 and 6 don't say. > > I was going to quibble with that, saying that 5 requires an optimization > that is only allowed at the moment, but I see that is covered by your take > on "necessarily" in point 1. OK. > How would you see the semantics being explicated? The implicit access all > method, or the implicit in out parameter method, or something else? I suggest that 'in out' params are the closest things to the semantics you want. - Bob