Mercurial > hg > CbC > CbC_gcc

comparison libstdc++-v3/include/ext/aligned_buffer.h @ 145:1830386684a0

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
gcc-9.2.0
author anatofuz
date Thu, 13 Feb 2020 11:34:05 +0900
parents 84e7813d76e9
children
comparison
equal deleted inserted replaced
131:84e7813d76e9 145:1830386684a0
1 // Aligned memory buffer -*- C++ -*- 1 // Aligned memory buffer -*- C++ -*-
2 2
3 // Copyright (C) 2013-2018 Free Software Foundation, Inc. 3 // Copyright (C) 2013-2020 Free Software Foundation, Inc.
4 // 4 //
5 // This file is part of the GNU ISO C++ Library. This library is free 5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the 6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the 7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option) 8 // Free Software Foundation; either version 3, or (at your option)
47 struct __aligned_membuf 47 struct __aligned_membuf
48 { 48 {
49 // Target macro ADJUST_FIELD_ALIGN can produce different alignment for 49 // Target macro ADJUST_FIELD_ALIGN can produce different alignment for
50 // types when used as class members. __aligned_membuf is intended 50 // types when used as class members. __aligned_membuf is intended
51 // for use as a class member, so align the buffer as for a class member. 51 // for use as a class member, so align the buffer as for a class member.
52 // Since GCC 8 we could just use alignof(_Tp) instead, but older
53 // versions of non-GNU compilers might still need this trick.
52 struct _Tp2 { _Tp _M_t; }; 54 struct _Tp2 { _Tp _M_t; };
53 55
54 alignas(__alignof__(_Tp2::_M_t)) unsigned char _M_storage[sizeof(_Tp)]; 56 alignas(__alignof__(_Tp2::_M_t)) unsigned char _M_storage[sizeof(_Tp)];
55 57
56 __aligned_membuf() = default; 58 __aligned_membuf() = default;
84 // and <bits/hashtable_policy.h>, but ideally they would use __aligned_membuf 86 // and <bits/hashtable_policy.h>, but ideally they would use __aligned_membuf
85 // instead, as it has smaller size for some types on some targets. 87 // instead, as it has smaller size for some types on some targets.
86 // This type is still used to avoid an ABI change. 88 // This type is still used to avoid an ABI change.
87 template<typename _Tp> 89 template<typename _Tp>
88 struct __aligned_buffer 90 struct __aligned_buffer
89 : std::aligned_storage<sizeof(_Tp), std::alignment_of<_Tp>::value> 91 : std::aligned_storage<sizeof(_Tp), __alignof__(_Tp)>
90 { 92 {
91 typename 93 typename
92 std::aligned_storage<sizeof(_Tp), std::alignment_of<_Tp>::value>::type 94 std::aligned_storage<sizeof(_Tp), __alignof__(_Tp)>::type _M_storage;
93 _M_storage;
94 95
95 __aligned_buffer() = default; 96 __aligned_buffer() = default;
96 97
97 // Can be used to avoid value-initialization 98 // Can be used to avoid value-initialization
98 __aligned_buffer(std::nullptr_t) { } 99 __aligned_buffer(std::nullptr_t) { }