220 35586 <3058817.kvbDme98ge@tjmaciei-mobl1> article Path: news.gmane.org!.POSTED!not-for-mail From: Thiago Macieira Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Rotational shift operator Date: Tue, 28 Nov 2017 17:33:24 -0800 Lines: 40 Approved: news@gmane.org Message-ID: <3058817.kvbDme98ge@tjmaciei-mobl1> References: <69593098-e2cc-487e-bd14-9001b27aa7c1@isocpp.org> <6888287.JoKhHhR3xM@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" X-Trace: blaine.gmane.org 1511919208 24920 195.159.176.226 (29 Nov 2017 01:33:28 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 29 Nov 2017 01:33:28 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCB4TK757YBRBZU47DIAKGQEFAT5Z6Q@isocpp.org Wed Nov 29 02:33:24 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qt0-f199.google.com ([209.85.216.199]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1eJrFY-0005wj-NT for gclcip-std-proposals@m.gmane.org; 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[2001:19f0:5:2221::1:3]) by mx.google.com with ESMTPS id y9si601652qtf.388.2017.11.28.17.33.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 28 Nov 2017 17:33:25 -0800 (PST) Received-SPF: pass (google.com: domain of thiago@macieira.org designates 2001:19f0:5:2221::1:3 as permitted sender) client-ip=2001:19f0:5:2221::1:3; Original-Received: from tjmaciei-mobl1.localnet (fmdmzpr03-ext.fm.intel.com [192.55.54.38]) by smtp.macieira.info (Postfix) with ESMTPSA id 52F562C5F for ; Tue, 28 Nov 2017 17:33:25 -0800 (PST) In-Reply-To: <6888287.JoKhHhR3xM@tjmaciei-mobl1> X-Original-Sender: thiago@macieira.org X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of thiago@macieira.org designates 2001:19f0:5:2221::1:3 as permitted sender) smtp.mailfrom=thiago@macieira.org Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:35586 Archived-At: On Tuesday, 28 November 2017 17:27:03 PST Thiago Macieira wrote: > What should, according to you, the following produce: > > 1U << functionThatReturns33(); > > Please answer bearing in mind that the SHL operation in assembly is only > specified to work with values less than 32. Any higher value may shift > everything, nothing, or shift by the modulo 32. Please answer in two cases: 1) regular context, the compiler could not inline functionThatReturns33() 2) constant expression context, the compiler can inline and did constant propagation in other words: $ cat a.cpp extern int functionThatReturns33(); unsigned u1 = 1U << functionThatReturns33(); $ cat b.cpp constexpr int constexpr33() { return 33; } int functionThatReturns33() { return constexpr33(); } constexpr unsigned u2 = 1U << constexpr33(); What are the values of u1 and u2, according to you? -- Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org Software Architect - Intel Open Source Technology Center -- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/3058817.kvbDme98ge%40tjmaciei-mobl1. .