From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from esa1.mentor.iphmx.com (esa1.mentor.iphmx.com [68.232.129.153]) by sourceware.org (Postfix) with ESMTPS id 66358385BF81 for ; Tue, 14 Jul 2020 17:24:11 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 66358385BF81 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=codesourcery.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=joseph_myers@mentor.com IronPort-SDR: BzIBXAkdZhrANcUjB9UQpOINKBiD7PgBDU1tIrGdHPOShsGmGdZSFsiIBGmi6qdfCnr4evNBIQ hmIxioP/bqMBbXGJdtIR9MI8fAqvQnzT1oRj+Hr8THjTbEPD20p5f1jrQ/qzthZ2AiC3xGgE+t KtF1jwHLrVE4HM3o2AurKqlF/RxN7w5J5OvMcbhATOYK0ZrDXOhAKqlp4NEeEU44IbqjeFm5WG Hk4ZOHNObYKbe6ZCpf+FFAlS3heNmmuX+h2RRHA8LrtwgehQtiYDIdcdatglSDxrw23LyLYU1h KXw= X-IronPort-AV: E=Sophos;i="5.75,352,1589270400"; d="scan'208";a="53049856" Received: from orw-gwy-02-in.mentorg.com ([192.94.38.167]) by esa1.mentor.iphmx.com with ESMTP; 14 Jul 2020 09:24:10 -0800 IronPort-SDR: x4jleMvDpq4E6VSGvuYlMsXTPWgTfSWXDKGg3SKRFIF6BpCpBmm68UFsGeuZXZJSYLuxJK78Hs pVYKggXTk0MutcddkSiCjb6T+3wDUTPMfEkmeh8bGET6uJnpf2RU0jshz/JAUOS1yQzs6oGHSQ Jm7CUlP4kaSDLurHlpNxFRgNl8tWjMnkDdgUSTVQwCk2ehygNlUxZAdd87RazvMaphhNQOErFv yDzTKgjSiZVSXneLce0yKcuPxlw77jZ51nGObyJV2fHBKOy7SJjc3ECvGu/BFFDxt+HmlSEgZQ fmQ= Date: Tue, 14 Jul 2020 17:24:05 +0000 From: Joseph Myers X-X-Sender: jsm28@digraph.polyomino.org.uk To: "Maciej W. Rozycki" CC: Andrew Waterman , Alistair Francis , Subject: Re: [PATCH v3 13/19] RISC-V: Add the RV32 libm-test-ulps In-Reply-To: Message-ID: References: <6f6f811cb3453c1de41c8cb542aace23162f90a0.1594568655.git.alistair.francis@wdc.com> <9616c122-ef62-5845-7d13-97577f8c0d57@redhat.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-Originating-IP: [137.202.0.90] X-ClientProxiedBy: SVR-IES-MBX-03.mgc.mentorg.com (139.181.222.3) To svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) X-Spam-Status: No, score=-3129.1 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS, KAM_DMARC_STATUS, SPF_HELO_PASS, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org 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: , X-List-Received-Date: Tue, 14 Jul 2020 17:24:12 -0000 On Tue, 14 Jul 2020, Maciej W. Rozycki via Libc-alpha wrote: > Well, yes. I just ran `make regen-ulps' consecutively with different > `test-wrapper*' variables each time so as to redirect execution either to > my HiFive Unleashed board or (user-mode) QEMU. I have double-checked the > logs now and no rebuild was made for subsequent runs, so the very same > executables and DSOs were used. So picking one function and setting its ulps back to the lower value, then rerunning the test on whichever of hardware and QEMU gave the higher value, should result in a test log showing a specific input to a specific function (in a specific rounding mode) for which the results on hardware and QEMU differ. After confirming the difference with a minimal test just making that one function call, it should be possible to trace the execution of the function, whether in a debugger or inserting printf calls, to find the exact instruction for which hardware and QEMU produce different results with the same inputs. -- Joseph S. Myers joseph@codesourcery.com