From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp12.migadu.com ([2001:41d0:2:c151::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by ms9.migadu.com with LMTPS id JoDVBXbPGGSA4QAASxT56A (envelope-from ) for ; Mon, 20 Mar 2023 22:26:14 +0100 Received: from aspmx2.migadu.com ([2001:41d0:2:c151::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp12.migadu.com with LMTPS id 0MzWBHbPGGQQNgAAauVa8A (envelope-from ) for ; Mon, 20 Mar 2023 22:26:14 +0100 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by aspmx2.migadu.com (Postfix) with ESMTPS id CB65338A5F for ; Mon, 20 Mar 2023 22:26:13 +0100 (CET) Authentication-Results: aspmx2.migadu.com; dkim=none; dmarc=none; spf=pass (aspmx2.migadu.com: domain of "guix-devel-bounces+larch=yhetil.org@gnu.org" designates 209.51.188.17 as permitted sender) smtp.mailfrom="guix-devel-bounces+larch=yhetil.org@gnu.org" ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1679347573; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=m3O0enwcNMp6ZAW710353eiew4uriJMgxlNfINN0DhE=; b=lmkvs5Ukt14cAzbTE9e6aaAbm0Pd/uK2XAvYzmcgdeud2GHxb0kCBlMr35NG9jZ9WKLymA fsgbUIMQB8388XWh9YJA5wQ81x7HdWpGiNiUTz/ZldymB+QKtMHdGs4lxa2VoC4Hd70XdO 8fWUeB16lVGAqAqBYTF66KjaYOqabHBgmJCIf0ui8llNWQi/hABrTALk2+y8oWyqRr0Tbm wdmwDqYQafSYSmk2kEImHYHg0HtKVRjpQ8/7KTSzWuN/H8giPZo3tUBphP9KoIbY5vBPcD 56TdV8rOk1ca2/fGmG/bHfFjRGxrk073TnVdpqMfVfJfZjApslCobMcX8Tyz5A== ARC-Authentication-Results: i=1; aspmx2.migadu.com; dkim=none; dmarc=none; spf=pass (aspmx2.migadu.com: domain of "guix-devel-bounces+larch=yhetil.org@gnu.org" designates 209.51.188.17 as permitted sender) smtp.mailfrom="guix-devel-bounces+larch=yhetil.org@gnu.org" ARC-Seal: i=1; s=key1; d=yhetil.org; t=1679347573; a=rsa-sha256; cv=none; b=SyeD4/p0QCKQLgZuPTWgZY5lOia+HR4uBbpj3MG+t5CEtgLmrm98PjW4ZfMl4pRW5tYEp4 +nkaIkYjtKAYoi0nwOPBNb0v8XgZwQ97k6ody/4uqLeh11nYjl5vuNe8WcYAdDLcgHVALl DSxkwoIyBU2hIKm1ZYYjmF6zybTkCiNOVG4HkYo51b2sgRpUHRDxxIh61hZlPBAbdR166K BGxu3+5ui+vZWEOGhWLgfOv3wrNoTOM6jh9VNszS61oerqSUyCbHm+TJgAQJwdqS/1KCo5 Oec6Ndl9kcs8DLoL7dovxlN5+MYadMM6T5t3+VFUvFJzeTb4vd2FyjmCfHsusA== Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1peN0n-0006WH-HD; Mon, 20 Mar 2023 17:25:49 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1peN0k-0006Ut-MD for guix-devel@gnu.org; Mon, 20 Mar 2023 17:25:46 -0400 Received: from hera.aquilenet.fr ([2a0c:e300::1]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1peN0i-00070T-MG for guix-devel@gnu.org; Mon, 20 Mar 2023 17:25:46 -0400 Received: from localhost (localhost [127.0.0.1]) by hera.aquilenet.fr (Postfix) with ESMTP id E3207C74; Mon, 20 Mar 2023 22:25:39 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at hera.aquilenet.fr Received: from hera.aquilenet.fr ([127.0.0.1]) by localhost (hera.aquilenet.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 0MC_-wywg65h; Mon, 20 Mar 2023 22:25:39 +0100 (CET) Received: from jurong (unknown [IPv6:2001:861:c4:f2f0::c64]) by hera.aquilenet.fr (Postfix) with ESMTPSA id 0445C6DF; Mon, 20 Mar 2023 22:25:38 +0100 (CET) Date: Mon, 20 Mar 2023 22:25:37 +0100 From: Andreas Enge To: Michael Schierl Cc: guix-devel@gnu.org Subject: Re: Procps in core-updates Message-ID: References: <83194a1d-4589-aed9-09a3-5d1495d06699@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <83194a1d-4589-aed9-09a3-5d1495d06699@gmx.de> Received-SPF: pass client-ip=2a0c:e300::1; envelope-from=andreas@enge.fr; helo=hera.aquilenet.fr X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: guix-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: X-Migadu-Queue-Id: CB65338A5F X-Spam-Score: -3.85 X-Migadu-Spam-Score: -3.85 X-Migadu-Scanner: scn0.migadu.com List-Help: List-Subscribe: , Errors-To: guix-devel-bounces+larch=yhetil.org@gnu.org Sender: guix-devel-bounces+larch=yhetil.org@gnu.org X-Migadu-Country: US X-Migadu-Flow: FLOW_IN X-TUID: nG0++gR5Tgm+ Am Mon, Mar 20, 2023 at 09:02:01PM +0100 schrieb Michael Schierl: > Seems that you accidentally attached the object file (binary) instead of > the assembly output. :-) Hm, I had accidentally written the assembly output to a .o file, and then apparently accidentally overwritten the file before attaching it :-( > > The weirdest thing is that actually the value is the integer 123. So it > > should be stored in any kind of register exactly. > 123 as a normalized binary floating point number would be > 1.921875 × 2⁶ > and you would have to represent the mantissa in binary (1.111011₂). > Still this should fit into most floating point registers easily. Exactly! 7 bits of mantissa would be enough. > But possibly the value computed by the algorithm of parsing the number > resulted in e.g. > 1.111011000000000000000000000000000000000000000000000001011₂ × 2⁶ I looked at the algorithm, it uses a Horner scheme ((1*10)+2)*10+3, so everything should fit in every step and be fine. I mentioned the problem to colleagues, who told me "this is the well-known GCC bug 323": https://gcc.gnu.org/bugzilla/show_bug.cgi?id=323 And they pointed me to even crazier things, errors even after casting floating point numbers to integers in cases where gcc "optimises" the code: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102930 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85957 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93681 Enjoy the output z = 0 z is one coming from int z = opaque(1) + 0x1p-60 == 1; printf("z = %d\n", z); if (z) puts("z is one"); ! It looks like a quantum computer, z is a superposition of 0 and 1 :) Andreas