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@kaizen_nagoya(Dr. Kiyoshi Ogawa)

C++N4606 (237) 18.6.5 Hardware interference size[hardware.interference]p506

Last updated at Posted at 2018-04-29

#はじめに(Introduction)
C++N4606 Working Draft, Standard for Programming Language C++
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/#mailing2016-11
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/n4606.pdf

C++N4606は、ISO/IEC JTC1 SC22 WG21の作業原案(Working Draft)です。
公式のISO/IEC 14882原本ではありません。
ISO/IEC JTC1 SC22 WG21では、可能な限り作業文書を公開し、幅広い意見を求めています。
一連の記事はコード断片をコンパイルできる形にする方法を検討してコンパイル、リンク、実行して、規格案の原文と処理系(g++, Clang++)との違いを確認し、技術内容を検討し、ISO/IEC JTC1 SC22 WG21にフィードバックするために用います。
また、CERT C++, MISRA C++等のコーディング標準のコード断片をコンパイルする際の参考にさせていただこうと考えています。CERT C++, MISRA C++が標準化の動きとの時間的なずれがあれば確認できれば幸いです。また、boostライブラリとの関連、Linux OS, TOPPERSカーネル、g++(GCC), clang++(LLVM）との関係も調査中です。
何か、抜け漏れ、耳より情報がありましたらおしらせくださると幸いです。

##作業方針(sequence)
１）コンパイルエラーを収集する。
２）コンパイルエラーをなくす方法を検討する。
コンパイルエラーになる例を示すだけが目的のコードは、コンパイルエラーをなくすのではなく、コンパイルエラーの種類を収集するだけにする。
文法を示すのが目的のコード場合に、コンパイルエラーをなくすのに手間がかかる場合は、順次作業します。
３）リンクエラーをなくす方法を検討する。
文法を示すのが目的のコード場合に、リンクエラーをなくすのに手間がかかる場合は、順次作業します。
４）意味のある出力を作る。
コンパイル、リンクが通っても、意味のある出力を示そうとすると、コンパイル・リンクエラーが出て収拾できそうにない場合がある。順次作業します。

１）だけのものから４）まで進んだものと色々ある状態です。一歩でも前に進むご助言をお待ちしています。「検討事項」の欄に現状を記録するようにしています。

C++N4606符号断片編纂一覧(example code compile list)

C++N4606 Working Draft 2016, ISO/IEC 14882, C++ standard(1) Example code compile list
https://qiita.com/kaizen_nagoya/items/df5d62c35bd6ed1c3d43/

編纂器(Compiler)

###clang++ --version
clang version 6.0.0 (tags/RELEASE_600/final)
Target: x86_64-apple-darwin17.4.0

###g++-7 --version
g++-7 (Homebrew GCC 7.3.0_1) 7.3.0
Copyright (C) 2017 Free Software Foundation, Inc.

#(237) 18.6.5 Hardware interference size[hardware.interference]p506
##算譜(source code)

p506.cpp
// C++N4606 Committee Draft, Standard for Programming Language C++
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/n4606.pdf
#define msg "C++N4606(237) 18.6.5 Hardware interference size[hardware.interference]p506.cpp"
// Edited by Dr. Ogawa Kiyoshi. Compile procedure and results record.

#include <iostream>
#include <cstdlib>
#include <new>
#include <atomic>

struct keep_apart {
alignas(hardware_destructive_interference_size) atomic<int> cat;
alignas(hardware_destructive_interference_size) atomic<int> dog;
};
struct together {
atomic<int> dog;
int puppy;
};
struct kennel {
// Other data members...
alignas(sizeof(together)) together pack;
// Other data members...
};

int main() {
static_assert(sizeof(together) <= hardware_constructive_interference_size);
  std::cout<< msg << std::endl;
  return EXIT_SUCCESS;
}

##編纂・実行結果(compile and go)

cppgl17.sh
$ ./cppall.sh p506
$ clang++ p506.cpp -std=c++03 -Wall
p506.cpp:14:1: error: unknown type name 'alignas'
alignas(hardware_destructive_interference_size) atomic<int> cat;
^
p506.cpp:14:48: error: expected ';' at end of declaration list
alignas(hardware_destructive_interference_size) atomic<int> cat;
                                               ^
                                               ;
p506.cpp:15:1: error: unknown type name 'alignas'
alignas(hardware_destructive_interference_size) atomic<int> dog;
^
p506.cpp:15:9: error: duplicate member 'hardware_destructive_interference_size'
alignas(hardware_destructive_interference_size) atomic<int> dog;
        ^
p506.cpp:14:9: note: previous declaration is here
alignas(hardware_destructive_interference_size) atomic<int> cat;
        ^
p506.cpp:15:48: error: expected ';' at end of declaration list
alignas(hardware_destructive_interference_size) atomic<int> dog;
                                               ^
                                               ;
p506.cpp:23:9: error: expected parameter declarator
alignas(sizeof(together)) together pack;
        ^
p506.cpp:23:9: error: expected ')'
p506.cpp:23:8: note: to match this '('
alignas(sizeof(together)) together pack;
       ^
p506.cpp:23:1: error: C++ requires a type specifier for all declarations
alignas(sizeof(together)) together pack;
^
p506.cpp:23:26: error: expected ';' at end of declaration list
alignas(sizeof(together)) together pack;
                         ^
                         ;
p506.cpp:28:74: error: too few arguments provided to function-like macro invocation
static_assert(sizeof(together) <= hardware_constructive_interference_size);
                                                                         ^
/usr/local/Cellar/llvm/6.0.0/include/c++/v1/__config:805:12: note: macro 'static_assert' defined here
#   define static_assert(__b, __m) _Static_assert(__b, __m)
           ^
p506.cpp:28:1: error: use of undeclared identifier 'static_assert'
static_assert(sizeof(together) <= hardware_constructive_interference_size);
^
11 errors generated.
$ clang++ p506.cpp -std=c++11 -Wall
p506.cpp:14:9: error: use of undeclared identifier 'hardware_destructive_interference_size'
alignas(hardware_destructive_interference_size) atomic<int> cat;
        ^
p506.cpp:15:9: error: use of undeclared identifier 'hardware_destructive_interference_size'
alignas(hardware_destructive_interference_size) atomic<int> dog;
        ^
p506.cpp:28:35: error: use of undeclared identifier 'hardware_constructive_interference_size'
static_assert(sizeof(together) <= hardware_constructive_interference_size);
                                  ^
3 errors generated.
$ clang++ p506.cpp -std=c++17 -Wall
p506.cpp:14:9: error: use of undeclared identifier 'hardware_destructive_interference_size'
alignas(hardware_destructive_interference_size) atomic<int> cat;
        ^
p506.cpp:15:9: error: use of undeclared identifier 'hardware_destructive_interference_size'
alignas(hardware_destructive_interference_size) atomic<int> dog;
        ^
p506.cpp:28:35: error: use of undeclared identifier 'hardware_constructive_interference_size'
static_assert(sizeof(together) <= hardware_constructive_interference_size);
                                  ^
3 errors generated.

$ g++-7 p506.cpp -std=c++03  -Wall
In file included from /usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/atomic:38:0,
                 from p506.cpp:9:
/usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/bits/c++0x_warning.h:32:2: error: #error This file requires compiler and library support for the ISO C++ 2011 standard. This support must be enabled with the -std=c++11 or -std=gnu++11 compiler options.
 #error This file requires compiler and library support \
  ^~~~~
p506.cpp:28:1: warning: identifier 'static_assert' is a keyword in C++11 [-Wc++11-compat]
 static_assert(sizeof(together) <= hardware_constructive_interference_size);
 ^~~~~~~~~~~~~
p506.cpp:14:9: error: 'hardware_destructive_interference_size' has not been declared
 alignas(hardware_destructive_interference_size) atomic<int> cat;
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
p506.cpp:14:47: error: ISO C++ forbids declaration of 'alignas' with no type [-fpermissive]
 alignas(hardware_destructive_interference_size) atomic<int> cat;
                                               ^
p506.cpp:14:47: error: expected ';' at end of member declaration
p506.cpp:14:49: error: 'atomic' does not name a type; did you mean 'atoi'?
 alignas(hardware_destructive_interference_size) atomic<int> cat;
                                                 ^~~~~~
                                                 atoi
p506.cpp:15:9: error: 'hardware_destructive_interference_size' has not been declared
 alignas(hardware_destructive_interference_size) atomic<int> dog;
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
p506.cpp:15:47: error: ISO C++ forbids declaration of 'alignas' with no type [-fpermissive]
 alignas(hardware_destructive_interference_size) atomic<int> dog;
                                               ^
p506.cpp:15:47: error: expected ';' at end of member declaration
p506.cpp:15:1: error: 'int keep_apart::alignas(int)' cannot be overloaded
 alignas(hardware_destructive_interference_size) atomic<int> dog;
 ^~~~~~~
p506.cpp:14:1: error: with 'int keep_apart::alignas(int)'
 alignas(hardware_destructive_interference_size) atomic<int> cat;
 ^~~~~~~
p506.cpp:15:49: error: 'atomic' does not name a type; did you mean 'atoi'?
 alignas(hardware_destructive_interference_size) atomic<int> dog;
                                                 ^~~~~~
                                                 atoi
p506.cpp:18:1: error: 'atomic' does not name a type; did you mean 'atoi'?
 atomic<int> dog;
 ^~~~~~
 atoi
p506.cpp:23:9: error: expected identifier before 'sizeof'
 alignas(sizeof(together)) together pack;
         ^~~~~~
p506.cpp:23:9: error: expected ',' or '...' before 'sizeof'
p506.cpp:23:25: error: ISO C++ forbids declaration of 'alignas' with no type [-fpermissive]
 alignas(sizeof(together)) together pack;
                         ^
p506.cpp:23:25: error: expected ';' at end of member declaration
p506.cpp: In function 'int main()':
p506.cpp:28:35: error: 'hardware_constructive_interference_size' was not declared in this scope
 static_assert(sizeof(together) <= hardware_constructive_interference_size);
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
p506.cpp:28:1: error: 'static_assert' was not declared in this scope
 static_assert(sizeof(together) <= hardware_constructive_interference_size);
 ^~~~~~~~~~~~~

$ g++-7 p506.cpp -std=c++11  -Wall
p506.cpp:14:9: error: 'hardware_destructive_interference_size' was not declared in this scope
 alignas(hardware_destructive_interference_size) atomic<int> cat;
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
p506.cpp:15:9: error: 'hardware_destructive_interference_size' was not declared in this scope
 alignas(hardware_destructive_interference_size) atomic<int> dog;
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
p506.cpp: In function 'int main()':
p506.cpp:28:35: error: 'hardware_constructive_interference_size' was not declared in this scope
 static_assert(sizeof(together) <= hardware_constructive_interference_size);
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

$ g++-7 p506.cpp -std=c++17  -Wall
p506.cpp:14:9: error: 'hardware_destructive_interference_size' was not declared in this scope
 alignas(hardware_destructive_interference_size) atomic<int> cat;
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
p506.cpp:15:9: error: 'hardware_destructive_interference_size' was not declared in this scope
 alignas(hardware_destructive_interference_size) atomic<int> dog;
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
p506.cpp: In function 'int main()':
p506.cpp:28:35: error: 'hardware_constructive_interference_size' was not declared in this scope
 static_assert(sizeof(together) <= hardware_constructive_interference_size);
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

#検討事項(agenda)
ヘッダで定義して要るとのこと要確認。
http://en.cppreference.com/w/cpp/thread/hardware_destructive_interference_size
役に立つまたは意味のある出力

#参考資料(reference)

N4606 Working Draft 2016, ISO/IEC 14882, C++ standardのコード断片をコンパイルするためにしていること
https://qiita.com/kaizen_nagoya/items/a8d7ee2f2e29e76c19c1

コンパイル用shell script C版(clangとgcc)とC++版(clang++とg++)
https://qiita.com/kaizen_nagoya/items/74220c0577a512c2d7da

Clang/Clang++(LLVM) gcc/g++(GNU) コンパイラ警告等比較
https://qiita.com/kaizen_nagoya/items/9a82b958cc3aeef0403f

Qiitaに投稿するCのStyle例(暫定)
https://qiita.com/kaizen_nagoya/items/946df1528a6a1ef2bc0d

MISRA C++ 5-0-16
https://qiita.com/kaizen_nagoya/items/7df2d4e05db724752a74

C++ Templates Part1 BASICS Chapter 3. Class Templates 3.2 Use of Class Template Stack stack1test.cpp
https://qiita.com/kaizen_nagoya/items/cd5fc49106fad5a4e9ed

ISO/IEC TS 17961:2013 C Secure Coding Rules(1) All list(to be confirmed)
https://qiita.com/kaizen_nagoya/items/54e056195c4f11b850a1

C言語（C++)に対する誤解、曲解、無理解、爽快。
https://qiita.com/kaizen_nagoya/items/3f3992c9722c1cee2e3a

C Puzzle Bookの有り難み5つ、C言語規格及びCコンパイラの特性を認識
https://qiita.com/kaizen_nagoya/items/d89a48c1536a02ecdec9

'wchar.h' file not found で困った clang++ macOS
https://qiita.com/kaizen_nagoya/items/de15cd46d657517fac11

Open POSIX Test Suiteの使い方を調べはじめました
https://qiita.com/kaizen_nagoya/items/644d5e407f5faf96e6dc

MISRA-C 2012 Referenceに掲載している文献の入手可能性を確認
https://qiita.com/kaizen_nagoya/items/96dc8b125e462d5575bb

どうやって MISRA Example Suiteをコンパイルするか
https://qiita.com/kaizen_nagoya/items/fbdbff5ff696e2ca7f00

MISRA C まとめ #include
https://qiita.com/kaizen_nagoya/items/f1a79a7cbd281607c7c9

「C++完全理解ガイド」の同意できること上位10
https://qiita.com/kaizen_nagoya/items/aa5744e0c4a8618c7671

#文書履歴(document history)
ver. 0.10 初稿 20180429

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