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 [63.128.21.124]) by sourceware.org (Postfix) with ESMTP id 8F5B03850432 for ; Mon, 28 Sep 2020 09:32:28 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 8F5B03850432 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-596-RggjIVj1MLCxTei3UBbpxQ-1; Mon, 28 Sep 2020 05:32:24 -0400 X-MC-Unique: RggjIVj1MLCxTei3UBbpxQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A9652186DD21; Mon, 28 Sep 2020 09:32:23 +0000 (UTC) Received: from localhost (unknown [10.33.36.3]) by smtp.corp.redhat.com (Postfix) with ESMTP id 536DC27CC1; Mon, 28 Sep 2020 09:32:20 +0000 (UTC) Date: Mon, 28 Sep 2020 10:32:19 +0100 From: Jonathan Wakely To: Patrick Palka Cc: gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org Subject: Re: [PATCH 2/4] libstdc++: Reduce the size of a subrange with empty sentinel type Message-ID: <20200928093219.GB3946@redhat.com> References: <20200928044854.46674-1-ppalka@redhat.com> <20200928044854.46674-2-ppalka@redhat.com> MIME-Version: 1.0 In-Reply-To: <20200928044854.46674-2-ppalka@redhat.com> X-Clacks-Overhead: GNU Terry Pratchett X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline X-Spam-Status: No, score=-13.8 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H5, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 28 Sep 2020 09:32:29 -0000 On 28/09/20 00:48 -0400, Patrick Palka via Libstdc++ wrote: >libstdc++-v3/ChangeLog: > > * include/bits/ranges_util.h (subrange::_M_end): Give it > [[no_unique_adcress]]. > * testsuite/std/ranges/subrange/sizeof.cc: New test. OK. > libstdc++-v3/include/bits/ranges_util.h | 2 +- > .../testsuite/std/ranges/subrange/sizeof.cc | 28 +++++++++++++++++++ > 2 files changed, 29 insertions(+), 1 deletion(-) > create mode 100644 libstdc++-v3/testsuite/std/ranges/subrange/sizeof.cc > >diff --git a/libstdc++-v3/include/bits/ranges_util.h b/libstdc++-v3/include/bits/ranges_util.h >index 694ae796399..a98658ff5c8 100644 >--- a/libstdc++-v3/include/bits/ranges_util.h >+++ b/libstdc++-v3/include/bits/ranges_util.h >@@ -208,7 +208,7 @@ namespace ranges > = _Kind == subrange_kind::sized && !sized_sentinel_for<_Sent, _It>; > > _It _M_begin = _It(); >- _Sent _M_end = _Sent(); >+ [[no_unique_address]] _Sent _M_end = _Sent(); > > template > struct _Size >diff --git a/libstdc++-v3/testsuite/std/ranges/subrange/sizeof.cc b/libstdc++-v3/testsuite/std/ranges/subrange/sizeof.cc >new file mode 100644 >index 00000000000..7e95e196c6c >--- /dev/null >+++ b/libstdc++-v3/testsuite/std/ranges/subrange/sizeof.cc >@@ -0,0 +1,28 @@ >+// Copyright (C) 2020 Free Software Foundation, Inc. >+// >+// This file is part of the GNU ISO C++ Library. This library is free >+// software; you can redistribute it and/or modify it under the >+// terms of the GNU General Public License as published by the >+// Free Software Foundation; either version 3, or (at your option) >+// any later version. >+ >+// This library is distributed in the hope that it will be useful, >+// but WITHOUT ANY WARRANTY; without even the implied warranty of >+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the >+// GNU General Public License for more details. >+ >+// You should have received a copy of the GNU General Public License along >+// with this library; see the file COPYING3. If not see >+// . >+ >+// { dg-options "-std=gnu++2a" } >+// { dg-do compile { target c++2a } } >+ >+#include >+#include >+ >+// Verify we optimize away the 'end' data member of a subrange with an empty >+// sentinel type. >+static_assert(sizeof(std::ranges::subrange, >+ std::default_sentinel_t>) >+ == sizeof(std::counted_iterator)); >-- >2.28.0.618.g9bc233ae1c >