From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5CA35C433DF for ; Tue, 23 Jun 2020 18:42:53 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 2BC6C20781 for ; Tue, 23 Jun 2020 18:42:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fwNZ1/tZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2BC6C20781 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:37278 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jnnsi-0000iu-D4 for qemu-devel@archiver.kernel.org; Tue, 23 Jun 2020 14:42:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44400) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jnnrV-0007nt-Sc for qemu-devel@nongnu.org; Tue, 23 Jun 2020 14:41:37 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:24356 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jnnrT-0001b0-84 for qemu-devel@nongnu.org; Tue, 23 Jun 2020 14:41:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1592937693; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=12a5z3buWkBG2zVwDiqHiOQMoVyyNxKToEo7rcgO9IE=; b=fwNZ1/tZ6KFahFtoquWv7Bqj3kl7z0w0BVmpKjLIqUBwrlaEU9SYeW4bVhv5e/HWDW4Cv8 +guoyqlR7PY2+BGAp6dFYQyckLXWX7zc/9lk3h0S56xEgLpE/9lxgiWy1+iiMrFWr7HckN tSPI/7+Xsy6Cqxal/DIIqiBvZ/XC5OE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-8-i2nv-lDdP_6qAtEDzKT7vQ-1; Tue, 23 Jun 2020 14:41:17 -0400 X-MC-Unique: i2nv-lDdP_6qAtEDzKT7vQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A1BE0800597 for ; Tue, 23 Jun 2020 18:41:16 +0000 (UTC) Received: from [10.3.114.107] (ovpn-114-107.phx2.redhat.com [10.3.114.107]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6F87A5D9D3; Tue, 23 Jun 2020 18:41:16 +0000 (UTC) Subject: Re: [PATCH] configure: disable -Wxor-used-as-pow To: Paolo Bonzini , qemu-devel@nongnu.org References: <20200623173726.20909-1-pbonzini@redhat.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Tue, 23 Jun 2020 13:41:15 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200623173726.20909-1-pbonzini@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=205.139.110.120; envelope-from=eblake@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/23 01:53:54 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 6/23/20 12:37 PM, Paolo Bonzini wrote: > Clang being clang and adding more pointless warnings. In a hardware > emulator there are going to be plenty of bitwise operations, and the > chance of someone writing ^ for pow and not being caught is basically > zero. Did this warning actually fire? My understanding (from a quick glance of https://reviews.llvm.org/D63423) is that it is supposed to catch instances of '2 ^ 16' where someone meant '1 << 16' instead of 18. I don't know if it is supposed to flag 'a ^ 16' (if it does, then it is indeed useless), or only when both lhs and rhs are constants and where lhs is 2 or 10, so my initial reaction is that without seeing an actual false positive, we are premature in disabling it. > > Signed-off-by: Paolo Bonzini > --- > configure | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/configure b/configure > index 8d9435a0e0..d42f060ee7 100755 > --- a/configure > +++ b/configure > @@ -2062,6 +2062,7 @@ add_to nowarn_flags -Wno-string-plus-int > add_to nowarn_flags -Wno-typedef-redefinition > add_to nowarn_flags -Wno-tautological-type-limit-compare > add_to nowarn_flags -Wno-psabi > +add_to nowarn_flags -Wno-xor-used-as-pow Pre-existing, but is it worth ordering flag additions in alphabetical order (the three preceding lines are in the wrong order if so). -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org