From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 127326 invoked by alias); 1 Feb 2017 21:37:31 -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 127313 invoked by uid 89); 1 Feb 2017 21:37:30 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.4 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,RCVD_IN_SORBS_SPAM,SPF_PASS autolearn=no version=3.3.2 spammy=cures, exclude, PR79286, benefited X-HELO: mail-pg0-f65.google.com Received: from mail-pg0-f65.google.com (HELO mail-pg0-f65.google.com) (74.125.83.65) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 01 Feb 2017 21:37:29 +0000 Received: by mail-pg0-f65.google.com with SMTP id 194so35280416pgd.0 for ; Wed, 01 Feb 2017 13:37:29 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=hniNn6uVipMWJXIHOoc+xhWU9O98mrnTj3LlbN2EZ3U=; b=rSEkDhafg/7t6pKyPSJ/wNY5FGAUI96UUwpiZlL7Y0kQ1g0pneeT2MaC+0VF392dbB gxZdcQtfz4y5Mw0NJvrVQR5hJRGRdhOzbpWbRDEdXlKQoWcTkYn25nc6i9M1I5OYvDC+ obh7bwDWbRIvFnLFyFBVQuA9aHXB8NR8VfyNDfbG3ohuKip/uctOoUjD9VSTIRuOZLAG Y3tQwidu3Uxp3N5BKVxc2Zn3FPA1IOvOti5Cu7Qe3YTIN++4wx+ddwh4++MNyh1VIcNQ m0HXkXUVuorVGaWQNV1tu33beJIn+g1s1O6hI+9cu78Httd5weGdztCudT6hUvncgV+n qdiA== X-Gm-Message-State: AIkVDXIBxpIEgop8UPmXSk8dLvppA1DPG1RgHnavXEIVH9ftV+mM/A14iFbVGEQx6XnLUg== X-Received: by 10.84.214.16 with SMTP id h16mr7511480pli.11.1485985047388; Wed, 01 Feb 2017 13:37:27 -0800 (PST) Received: from bubble.grove.modra.org (CPE-58-160-71-80.tyqh2.lon.bigpond.net.au. [58.160.71.80]) by smtp.gmail.com with ESMTPSA id a2sm52045525pfc.72.2017.02.01.13.37.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 01 Feb 2017 13:37:26 -0800 (PST) Received: by bubble.grove.modra.org (Postfix, from userid 1000) id B2EEDC318C; Thu, 2 Feb 2017 08:07:22 +1030 (ACDT) Date: Wed, 01 Feb 2017 21:37:00 -0000 From: Alan Modra To: gcc-patches@gcc.gnu.org Subject: Re: PR79286, ira combine_and_move_insns in loops Message-ID: <20170201213722.GB3731@bubble.grove.modra.org> References: <20170201134830.GA3731@bubble.grove.modra.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170201134830.GA3731@bubble.grove.modra.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-IsSubscribed: yes X-SW-Source: 2017-02/txt/msg00092.txt.bz2 On Thu, Feb 02, 2017 at 12:18:31AM +1030, Alan Modra wrote: > This patch cures PR79286 by restoring the REG_DEAD note test used > prior to r235660, but modified to only exclude insns that may trap. > I'd like to allow combine/move without a REG_DEAD note in loops > because insns in loops often lack such notes, and I recall seeing > quite a few cases at the time I wrote r235660 where loops benefited > from allowing the combine/move to happen. Ugh, the new testcase fails for x86 -m32 -Os, but not due to ira this time but rather reload. I haven't looked into what is going wrong in reload yet, but the net result is the same: The faulting mem read is moved before the printf call. There were no other testsuite regressions, apart from the random set of fails I have been getting for a long time on x86_64 for c-c++-common/ubsan/float-cast-overflow-10.c, c-c++-common/ubsan/float-cast-overflow-2.c, c-c++-common/ubsan/float-cast-overflow-8.c, and c-c++-common/ubsan/overflow-mul-4.c. What is the correct thing to do for a new testcase that fails like this? Add a dg-fail-if? Assuming I or someone else can't fix the reload fail. The new testcase -Os failure occurs on gcc-4.x, gcc-5 and gcc-6, but gcc-3.4 passes. -- Alan Modra Australia Development Lab, IBM