From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-x42f.google.com (mail-pf1-x42f.google.com [IPv6:2607:f8b0:4864:20::42f]) by sourceware.org (Postfix) with ESMTPS id 2E61B3858C52 for ; Sun, 27 Mar 2022 04:53:53 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 2E61B3858C52 Received: by mail-pf1-x42f.google.com with SMTP id w7so7105977pfu.11 for ; Sat, 26 Mar 2022 21:53:53 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:references:from:in-reply-to :content-transfer-encoding; bh=IhjeiyofWdUA/Esr8N9pZbmShDCViW3vbjes4NlADBQ=; b=SuWr6/M1jr2hQSDSnVsolXzvydDJP9NeWJP17L9OzGHoJBcmcMkMKHMsEmJEEJlCVq jMnbn0HNoB280F+uTiO7mNo2VzNbPXgOG2WBL99rB1TmQYACUBJNR7e810xYc9OORm2o LIADmiNoRzrOmnQxS8Kv2RLB0vi8KQoDbjurShlvGsJTTNPMdn+JuYyJ/Cs+/6dcV2E+ aTjrLEuqQX9CfFF3vDAdIgxU5JtGMggW6mXpYFp34cyAu6qf82+rqnGMG5zKKAmYDNe8 pkZDVcSRhzEs9F6hMW4VTzs4MIn73ynzcrAQUtMZlcsHsrdAPJbRxDBAA3jhuhy4J91f qExQ== X-Gm-Message-State: AOAM530+QGDtthbtJkeo1FIyyumbFdHrZZSzkjujcpqXGEq1Hq4MSTyd B2A46O9rO2wjNl9Zc51i7nsuDCRdF+fR1g== X-Google-Smtp-Source: ABdhPJzjiLXottNd6KhQMLBg5vlIb3U8xb0gyUBvTPmOjY3Ri8P5Yxy83O24S/GNsxwIn6FePymzrg== X-Received: by 2002:a63:8c2:0:b0:380:bfd8:9e10 with SMTP id 185-20020a6308c2000000b00380bfd89e10mr5611625pgi.422.1648356831666; Sat, 26 Mar 2022 21:53:51 -0700 (PDT) Received: from [172.31.0.204] (c-73-63-24-84.hsd1.ut.comcast.net. [73.63.24.84]) by smtp.gmail.com with ESMTPSA id k62-20020a17090a4cc400b001c7ea7f487asm6257658pjh.39.2022.03.26.21.53.51 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 26 Mar 2022 21:53:51 -0700 (PDT) Message-ID: <7891a681-4ec5-9659-68b2-57ce5e4e87d3@gmail.com> Date: Sat, 26 Mar 2022 22:53:50 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: Help with bisecting a test suite regression in GCC Content-Language: en-US To: gcc-help@gcc.gnu.org References: <11cb0554516ea651ca9d668d5748786ab675acef.camel@posteo.net> From: Jeff Law In-Reply-To: <11cb0554516ea651ca9d668d5748786ab675acef.camel@posteo.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-2.5 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gcc-help@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-help mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 27 Mar 2022 04:53:54 -0000 On 3/26/2022 4:41 PM, John Scott via Gcc-help wrote: > Hi, > > While working on upgrading the gcc-sh-elf Debian package from gcc 11 to > gcc 12, I think I've found a regression. I'm able to reproduce it with > an upstream bare-metal build. > > I've had a hard time figuring out how to bisect it. A naive run with > git bisect start > git bisect new . > git bisect old releases/gcc-11.2.0 > > fails with > The merge base 250f234988b6231669a720c52101d3686d645072 is new. > The property has changed between 250f234988b6231669a720c52101d3686d645072 and [7ca388565af176bd4efd4f8db1e5e9e11e98ef45]. > error: bisect run failed: 'git bisect--helper --bisect-state (null)' exited with error code -3 > > I'm not enough of a Git or GCC wizard to get further. Does anyone have > any advice so I can make an informative bug report? Bisection isn't really needed for a good bug report.  What's most important is to give complete sources, ideally a test which will exit with zero status for a success and call abort for failure. Compile the test with -save-temps and pass along the .i file so that we don't need your system header files.  Minimizing the amount of library bits your test needs is also helpful.  It's OK to use standard C library functions, but if you send us something linking against several libraries it's going to be harder for us to analyze what's really going on because we probably don't have those libraries. It's unlikely most of the developers are going to have SH hardware or even a setup that would let them run debian on qemu.  So if you've done any debugging to pinpoint what's happening at the assembly level, that's helpful.  We do have old gdb-sim simulators. So if your test is simple enough we may be able to debug it with that. jeff