From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 77FC9385840F for ; Fri, 24 Feb 2023 13:23:10 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 77FC9385840F Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1677244990; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references; bh=qs22gg/SlBOtm8eA/EYVLxu30jszN8iVVF3m6geCf2E=; b=gyW9ZxJ6QDRzKTnhCbuq6+KQn4v4jDXKfjNAJ2Lb0bghbmiV6KQyfKpYJVfI51JcnMggJV 6wjTl0pnP/cvPWrHHcIdzLyH1fl3DzuqW6tFsShUomfjBz6nbwT3M3Jdc6B6PRz0su1H/3 dCM/xklV5w4MVL+A9+5t9vsbCOG+7DI= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-641-3AHBNidFNyWqet2DR2Ay5Q-1; Fri, 24 Feb 2023 08:23:06 -0500 X-MC-Unique: 3AHBNidFNyWqet2DR2Ay5Q-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 039931C0512B; Fri, 24 Feb 2023 13:23:06 +0000 (UTC) Received: from tucnak.zalov.cz (unknown [10.39.192.62]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B70031121314; Fri, 24 Feb 2023 13:23:05 +0000 (UTC) Received: from tucnak.zalov.cz (localhost [127.0.0.1]) by tucnak.zalov.cz (8.17.1/8.17.1) with ESMTPS id 31ODMw8t871691 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Fri, 24 Feb 2023 14:22:58 +0100 Received: (from jakub@localhost) by tucnak.zalov.cz (8.17.1/8.17.1/Submit) id 31ODMv5x871690; Fri, 24 Feb 2023 14:22:57 +0100 Date: Fri, 24 Feb 2023 14:22:57 +0100 From: Jakub Jelinek To: Richard Biener Cc: Jonathan Wakely , gcc-patches@gcc.gnu.org Subject: Re: [PATCH 2/2] Avoid default-initializing auto_vec storage, fix vec Message-ID: Reply-To: Jakub Jelinek References: <20230224114444.7E2CE13246@imap2.suse-dmz.suse.de> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Spam-Status: No, score=-3.7 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Fri, Feb 24, 2023 at 12:15:04PM +0000, Richard Biener wrote: > > > Anyway, I wonder if you get the -Werror=stringop-overflow= errors during > > > bootstrap that I got with my version or not. > > Yes, I get this as well, not sure how to suppress it. I guess there's > no standard way to get at the address after some object without going > through uintptr obfuscation - and obviously we do not want to have > that (and if we optimize it away that doesn't help the diagnostic ...) As I wrote on IRC, incremental: --- gcc/vec.h 2023-02-24 11:54:49.859564268 +0100 +++ gcc/vec.h 2023-02-24 14:13:38.199163428 +0100 @@ -1553,7 +1553,8 @@ auto_vec () { m_auto.embedded_init (MAX (N, 2), 0, 1); - this->m_vec = &m_auto; + size_t off = (char *) &m_auto - (char *) this; + this->m_vec = (vec *) ((char *) this + off); } auto_vec (size_t s CXX_MEM_STAT_INFO) @@ -1565,7 +1566,8 @@ } m_auto.embedded_init (MAX (N, 2), 0, 1); - this->m_vec = &m_auto; + size_t off = (char *) &m_auto - (char *) this; + this->m_vec = (vec *) ((char *) this + off); } ~auto_vec () fixes the -Werror=stringop-overflow= errors for me during stage3, but haven't done full bootstrap. It is very ugly, but works. Jakub