From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS17314 8.43.84.0/22 X-Spam-Status: No, score=-3.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI,NICE_REPLY_A, PDS_RDNS_DYNAMIC_FP,RCVD_IN_DNSWL_MED,RDNS_DYNAMIC,SPF_HELO_PASS, SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (ip-8-43-85-97.sourceware.org [8.43.85.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id E19C81F8C6 for ; Fri, 30 Jul 2021 16:25:06 +0000 (UTC) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 10D50394CC3F for ; Fri, 30 Jul 2021 16:25:06 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 10D50394CC3F DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1627662306; bh=NqA3PtFzCy2AuGfkKBPyBQ2Y0MMsMYe0zbkXTWdrFHY=; h=Subject:To:References:Date:In-Reply-To:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=bSQVjvOiRaSME2fofWji/km0ef/irn3PAdx/0M2eWRNJM0cMY7d5atIC6yVCQ4Ssa so8Rk90rAm1TnL5L1rrOrAnLESSXEvtau6ItCVJLI2hEigi8QgajmqE7K6DhyHThP7 JGTH6VvOf54CGSCPQ6UqVqRgA5AZO+3mqJO5o5qE= Received: from mail-pj1-x1031.google.com (mail-pj1-x1031.google.com [IPv6:2607:f8b0:4864:20::1031]) by sourceware.org (Postfix) with ESMTPS id 308B33950C61 for ; Fri, 30 Jul 2021 16:22:23 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 308B33950C61 Received: by mail-pj1-x1031.google.com with SMTP id ca5so15896834pjb.5 for ; Fri, 30 Jul 2021 09:22:23 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=NqA3PtFzCy2AuGfkKBPyBQ2Y0MMsMYe0zbkXTWdrFHY=; b=dI9UKqncQMfoDYQ8km7Z6SJE1mnDoBxG2uBIs1TR3w0VBj9Yi1msakXyjuD9nti52A ZdDJkJQVKR67U1yNUw2OnpKIdpwCTUK8vnB8fUgiRfvjtBL7cEh7mE+9O8uA1gOmXyGN L+MT4kyFbcQ9k6/Nd/YAcHvCzNL8ps7ehpoMgZ1LPkHby4Fc0sNfgBe0p3hOqnZDb7Pd CTJ1NO9+wDSAZdQqzWU6sWiQNOkH6hnVY7x4gtcn002pQ9ENOn870Qu7cCzbF+4F6Tcf 9WGFiu1UTrk6htwUSwckcdK80iftXCIF8MDbEwcPOCkjGWmGEm2czDWQ3lPpMUub+AS7 K9fg== X-Gm-Message-State: AOAM533tSGu89GoboAt54VIAzsX0+5qJ1urZU2uItFHdAi0gaszQcsAB yXoirLcqGLeK7l9l5ZLOAFjTS005IB4= X-Google-Smtp-Source: ABdhPJwCxwIKJXkc5w1+l8dj/seXsTwaP7KcKZBsXn1k/g1WbWNbz/bfPTYqtnzKUtg69cPk3CnXnQ== X-Received: by 2002:a17:90a:c24b:: with SMTP id d11mr3922714pjx.91.1627662142092; Fri, 30 Jul 2021 09:22:22 -0700 (PDT) Received: from [192.168.1.24] (65-130-1-109.slkc.qwest.net. [65.130.1.109]) by smtp.gmail.com with ESMTPSA id z124sm3446580pgb.6.2021.07.30.09.22.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 30 Jul 2021 09:22:21 -0700 (PDT) Subject: Re: Failures building glibc with mainline GCC To: Aldy Hernandez , Joseph Myers References: Message-ID: Date: Fri, 30 Jul 2021 10:22:17 -0600 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Jeff Law via Libc-alpha Reply-To: Jeff Law Cc: "MacLeod, Andrew" , GCC Mailing List , Martin Sebor , libc-alpha@sourceware.org Errors-To: libc-alpha-bounces+e=80x24.org@sourceware.org Sender: "Libc-alpha" On 7/30/2021 10:19 AM, Aldy Hernandez via Libc-alpha wrote: > There's a new jump threader in GCC which is much more aggressive, and > may trigger latent problems with other warning passes, especially > -Warray-bounds, -Woverflow, and -Wuninitialized. > > Do your problems go away if you take out commit 2e96b5f14e? > > I have notes throughout the commit analyzing variants of the above > warnings (for example my addendum to gcc.c-torture/compile/pr83510.c). > So far, all the warnings I've seen are legitimate jump threading > opportunities that we are now doing, but which throw off the warning > passes. > > Before the inclusion of the new threader, I had warned that this could > happen. Perhaps we'll have to come up a way to reduce the false > positives. I should be able to get you testcases for at least some of these.  I strongly suspect it's the new threader.  First up will be the iconf stringop-overflow failures which should hit your inbox shortly. Jeff