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 [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 363BA3858D28 for ; Thu, 26 Jan 2023 14:51:13 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 363BA3858D28 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=1674744672; 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=pVmtKm3BJb6/j3/cT7GRQG4cmz+qhkg4mV5g4aoWZ2Q=; b=ZnbjT0SD8pu/y8krTJUYlmc78/70Z89sQJ9S3gUEgwVRL1ggN4UNRLlirI7dNgZsUzXTdn BI3apIeY07xfvb296TkTc5osY8imkpkxjZWIhcVRe/Dm60MNho4jCPTrlcoWSrOTQyy+2c kbE4rgD3crb0jbEAzpkz360q+fRU8q0= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-472-YdLpZT39PWGc6AxSkpqZ_A-1; Thu, 26 Jan 2023 09:51:11 -0500 X-MC-Unique: YdLpZT39PWGc6AxSkpqZ_A-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 85231100F913; Thu, 26 Jan 2023 14:51:11 +0000 (UTC) Received: from tucnak.zalov.cz (unknown [10.39.192.223]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3E9E8C15BAE; Thu, 26 Jan 2023 14:51:11 +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 30QEp8jr549731 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Thu, 26 Jan 2023 15:51:08 +0100 Received: (from jakub@localhost) by tucnak.zalov.cz (8.17.1/8.17.1/Submit) id 30QEp7Vs548683; Thu, 26 Jan 2023 15:51:07 +0100 Date: Thu, 26 Jan 2023 15:51:07 +0100 From: Jakub Jelinek To: Patrick Palka Cc: Andrew Pinski , gcc-patches@gcc.gnu.org, jason@redhat.com Subject: Re: [PATCH] constexprify some tree variables Message-ID: Reply-To: Jakub Jelinek References: <1668794731-9349-1-git-send-email-apinski@marvell.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 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=-3.5 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 Thu, Jan 26, 2023 at 09:45:35AM -0500, Patrick Palka via Gcc-patches wrote: > > -extern const unsigned char tree_code_length[]; > > + > > +#define DEFTREECODE(SYM, NAME, TYPE, LENGTH) LENGTH, > > +#define END_OF_BASE_TREE_CODES 0, > > +constexpr unsigned char tree_code_length[] = { > > +#include "all-tree.def" > > +}; > > + > > +#undef DEFTREECODE > > +#undef END_OF_BASE_TREE_CODES > > IIUC defining these globals as non-inline constexpr gives them internal > linkage, and so each TU contains its own unique copy of these globals. > This bloats cc1plus by a tiny bit and is technically an ODR violation > because some inline functions such as tree_class_check also ODR-use > these variables and so each defn of tree_class_check will refer to a > "different" tree_code_class. Since inline variables are a C++17 > feature, I guess we could fix this by defining the globals the old way > before C++17 and as inline constexpr otherwise? Agreed, just use __cpp_inline_variables >= 201606L to select between the old and new ways. Jakub