From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-relay-internal-0.canonical.com (smtp-relay-internal-0.canonical.com [185.125.188.122]) by sourceware.org (Postfix) with ESMTPS id 286963858C39 for ; Mon, 22 Aug 2022 08:52:16 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 286963858C39 Received: from mail-oo1-f72.google.com (mail-oo1-f72.google.com [209.85.161.72]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-internal-0.canonical.com (Postfix) with ESMTPS id 438C43F145 for ; Mon, 22 Aug 2022 08:52:15 +0000 (UTC) Received: by mail-oo1-f72.google.com with SMTP id z27-20020a4a655b000000b0044ad2d0eeacso5472041oog.18 for ; Mon, 22 Aug 2022 01:52:15 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc; bh=pB1/gdIwOb84pEUXC2JcDFsx4Wq/rHbKIIe3ExtQneM=; b=EqRxAishtlloRzDDTwo4DmgEZ9AFx72l9RShDNClc4vOvlkBKlGgKSQYkFUbBzoxom ed1FWEh8m/Mn860Uys2Sru5zY1+BrgbpPgP9qWXLVLZe5ROrHzM/uXY7Gm99464pWUWx bptkxAXki3B+gRoMJ3yNgWmzyJTlXBeGAwEqLCrMUZ0+/5uqlPuKn1Gdit2pxZb9EvC2 bxfhnm2NAXqvjqmffQhMwRTrE1RMmqv9d7/UDjTwM8MD6DIvjiUzvRtM4Fc0ivOhYd+k cuBnmg2+SRvdyXwR3eIftLpN6V7PeWvZAYn9xeHnceAIA8NmAKjwWnd6MBInxz67Wg93 8Bkw== X-Gm-Message-State: ACgBeo12QDtiyQrtJJ68SEkDC5OFYJVCF0f84ORTn6yrUvgbfNiZFmjn +3pJvkzngXKqmGW9M9eXjcveGC8LNsihfY25nTr4o1JFBhGpOOtOT4u+IzxVTLbuAWHSKfwyjCM xuK8KSya9fiZoeWb7mGgh4nJyHBwN5CvV+5Zr/vP0ZwMsWFWKm396XA== X-Received: by 2002:a05:6870:42cf:b0:11d:39a3:92a4 with SMTP id z15-20020a05687042cf00b0011d39a392a4mr2525230oah.131.1661158334136; Mon, 22 Aug 2022 01:52:14 -0700 (PDT) X-Google-Smtp-Source: AA6agR7hUNvaBnxobznbWZKjxgSVLDPycZ2c9XhflXswrQlRElgeR6gFvUgPBEfX82ebfR+WOHtzyqTadlwxH5kxfv4= X-Received: by 2002:a05:6870:42cf:b0:11d:39a3:92a4 with SMTP id z15-20020a05687042cf00b0011d39a392a4mr2525220oah.131.1661158333897; Mon, 22 Aug 2022 01:52:13 -0700 (PDT) MIME-Version: 1.0 References: <20220821104446.46521-1-michael.hudson@canonical.com> <20220822020419.137775-1-michael.hudson@canonical.com> In-Reply-To: From: Michael Hudson-Doyle Date: Mon, 22 Aug 2022 20:52:03 +1200 Message-ID: Subject: Re: [PATCH v2] Avoid undefined behaviour in ibm128 implementation of llroundl To: Andreas Schwab Cc: Michael Hudson-Doyle via Libc-alpha X-Spam-Status: No, score=-4.9 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, HTML_MESSAGE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.29 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: Mon, 22 Aug 2022 08:52:18 -0000 On Mon, 22 Aug 2022, 20:34 Andreas Schwab, wrote: > On Aug 22 2022, Michael Hudson-Doyle via Libc-alpha wrote: > > > @@ -69,7 +70,7 @@ __llroundl (long double x) > > res = hi + lo; > > The overflow happens here. Changing the type of the LHS does not change > that. > IIRC it was one of the "res += 1"s lower down in the test case that was failing for me. But maybe a more thorough rewrite of this function is called for (if people still care about ibm128 I guess). Cheers, mwh -- > Andreas Schwab, SUSE Labs, schwab@suse.de > GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 > "And now for something completely different." >