On 09/09/20 17:38 -0700, Thomas Rodgers wrote:
We would like to be able to use these things without having to pull in
the whole of <memory>.
* include/Makefile.am (bits_headers): Add new header.
* include/Makefile.in: Regenerate.
* include/bits/align.h: New file.
* include/std/memory (align): Move definition to bits/align.h.
(assume_aligned): Likewise.
---
libstdc++-v3/include/Makefile.am | 1 +
libstdc++-v3/include/Makefile.in | 1 +
libstdc++-v3/include/bits/align.h | 104 ++++++++++++++++++++++++++++++
libstdc++-v3/include/std/memory | 60 +----------------
4 files changed, 107 insertions(+), 59 deletions(-)
create mode 100644 libstdc++-v3/include/bits/align.h
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index bae97852348..eabec88219d 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -99,6 +99,7 @@ bits_srcdir = ${glibcxx_srcdir}/include/bits
bits_builddir = ./bits
bits_headers = \
${bits_srcdir}/algorithmfwd.h \
+ ${bits_srcdir}/align.h \
${bits_srcdir}/alloc_traits.h \
${bits_srcdir}/allocated_ptr.h \
${bits_srcdir}/allocator.h \
diff --git a/libstdc++-v3/include/bits/align.h
b/libstdc++-v3/include/bits/align.h
new file mode 100644
index 00000000000..593b337f897
--- /dev/null
+++ b/libstdc++-v3/include/bits/align.h
@@ -0,0 +1,104 @@
+// align implementation -*- C++ -*-
+
+// Copyright (C) 2008-2020 Free Software Foundation, Inc.
std::align was added in 2014 by
2f6ca9d31799133f80e446bd1faad5d9a67bac00 so that should be the first
date in the new file.
+//
+// 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.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file bits/align.h
+ * This is an internal header file, included by other library headers.
+ * Do not attempt to use it directly. @headername{memory}
+ */
+
+#ifndef _ALIGN_H
+#define _ALIGN_H 1
I'm a little worried this macro isn't unique enough and will clash
with something. Please use _GLIBCXX_ALIGN_H for the header guard
macro.
+
+#include <bits/c++config.h>
+
+#include <bit> // std::has_single_bit
+#include <stdint.h> // uintptr_t
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+/**
+ * @brief Fit aligned storage in buffer.
+ * @ingroup memory
+ *
+ * This function tries to fit @a __size bytes of storage with alignment
+ * @a __align into the buffer @a __ptr of size @a __space bytes. If such
+ * a buffer fits then @a __ptr is changed to point to the first byte of the
+ * aligned storage and @a __space is reduced by the bytes used for alignment.
+ *
+ * C++11 20.6.5 [ptr.align]
+ *
+ * @param __align A fundamental or extended alignment value.
+ * @param __size Size of the aligned storage required.
+ * @param __ptr Pointer to a buffer of @a __space bytes.
+ * @param __space Size of the buffer pointed to by @a __ptr.
+ * @return the updated pointer if the aligned storage fits, otherwise nullptr.
+ *
+ */
+inline void*
+align(size_t __align, size_t __size, void*& __ptr, size_t& __space) noexcept
+{
+#ifdef _GLIBCXX_USE_C99_STDINT_TR1
+ const auto __intptr = reinterpret_cast<uintptr_t>(__ptr);
+#else
+ // Cannot use std::uintptr_t so assume that std::size_t can be used instead.
+ static_assert(sizeof(size_t) >= sizeof(void*),
+ "std::size_t must be a suitable substitute for std::uintptr_t");
+ const auto __intptr = reinterpret_cast<unsigned long long>(__ptr);
Why on earth did I check that we can use size_t ... and then not use
size_t?! Not your problem though, that can be fixed separately.
OK for trunk with the copyright year and header guard changes, thanks!
