From 620db4ca608987ed3e386fad2fd80fa3886e8154 Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Mon, 28 Sep 2020 11:55:04 -0400 Subject: [PATCH] libstdc++: Reduce the size of a subrange with empty sentinel type libstdc++-v3/ChangeLog: * include/bits/ranges_util.h (subrange::_M_end): Give it [[no_unique_address]]. * testsuite/std/ranges/subrange/sizeof.cc: New test. --- 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)); -- 2.30.2