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: AS3215 2.6.0.0/16 X-Spam-Status: No, score=-3.9 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by dcvr.yhbt.net (Postfix) with ESMTP id CFDCD1F54E for ; Thu, 8 Sep 2022 18:16:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231386AbiIHSPl (ORCPT ); Thu, 8 Sep 2022 14:15:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47538 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230105AbiIHSPj (ORCPT ); Thu, 8 Sep 2022 14:15:39 -0400 Received: from cloud.peff.net (cloud.peff.net [104.130.231.41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 80F075F7D5 for ; Thu, 8 Sep 2022 11:15:35 -0700 (PDT) Received: (qmail 28243 invoked by uid 109); 8 Sep 2022 18:15:34 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with ESMTP; Thu, 08 Sep 2022 18:15:34 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 23318 invoked by uid 111); 8 Sep 2022 18:15:35 -0000 Received: from coredump.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.2) by peff.net (qpsmtpd/0.94) with (TLS_AES_256_GCM_SHA384 encrypted) ESMTPS; Thu, 08 Sep 2022 14:15:35 -0400 Authentication-Results: peff.net; auth=none Date: Thu, 8 Sep 2022 14:15:34 -0400 From: Jeff King To: Junio C Hamano Cc: git@vger.kernel.org, =?utf-8?B?w4Z2YXIgQXJuZmrDtnLDsA==?= Bjarmason Subject: Re: LSan curiosity in t1300 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Thu, Sep 08, 2022 at 11:03:05AM -0700, Junio C Hamano wrote: > > But if you run this in a debugger, you'll find that under -O2 the "key" > > variable has been optimized out! So LSan is producing the wrong result > > due to the optimization. It doesn't know that "key" is conceptually > > still reachable. > > Yikes. > > Is that related to the cause of the other patch from you, i.e. > wanting to get "registers" but unable to? If they manage to get the > value of the register that holds 'key', would this disappear, I > wonder? I don't think so. t1300 fails consistently for me with -O2, and it doesn't have the "register" message (and never came up as one of the racy losers). I think the "register" thing is mostly just a harmless warning that doesn't change the output, but simply confuses our "did lsan produce any logs" check. -Peff