From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 2424 invoked by alias); 26 Jun 2017 15:02:54 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 2403 invoked by uid 89); 26 Jun 2017 15:02:53 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE,SPF_PASS,URIBL_RED autolearn=ham version=3.3.2 spammy=Hx-languages-length:526 X-HELO: relay1.mentorg.com Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 26 Jun 2017 15:02:51 +0000 Received: from nat-ies.mentorg.com ([192.94.31.2] helo=svr-ies-mbx-01.mgc.mentorg.com) by relay1.mentorg.com with esmtp id 1dPVXM-0000sp-NK from joseph_myers@mentor.com ; Mon, 26 Jun 2017 08:02:48 -0700 Received: from digraph.polyomino.org.uk (137.202.0.87) by svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) with Microsoft SMTP Server (TLS) id 15.0.1263.5; Mon, 26 Jun 2017 16:02:40 +0100 Received: from jsm28 (helo=localhost) by digraph.polyomino.org.uk with local-esmtp (Exim 4.86_2) (envelope-from ) id 1dPVXA-0000Dn-8y; Mon, 26 Jun 2017 15:02:36 +0000 Date: Mon, 26 Jun 2017 15:02:00 -0000 From: Joseph Myers To: GCC Patches CC: Andrew Pinski Subject: Re: [PATCH] fold a * (a > 0 ? 1 : -1) to abs(a) and related optimizations In-Reply-To: Message-ID: References: User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-ClientProxiedBy: svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) To svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) X-SW-Source: 2017-06/txt/msg01931.txt.bz2 On Sat, 24 Jun 2017, Marc Glisse wrote: > * if X is NaN, we may get a qNaN with the wrong sign bit. We probably don't > care much though... The sign bit from a multiplication involving a NaN is not specified. *But* making any of these transformations with a qNaN loses the "invalid" exception from an ordered comparison involving a qNaN, so isn't valid in the case of (qNaNs respected and trapping-math). -- Joseph S. Myers joseph@codesourcery.com