替换已弃用的寄存器关键字C ++ 11 [英] Replacement for deprecated register keyword C++ 11

问题描述

我已阅读（此处），注册表关键字在C ++ 11中已弃用。因此，在较新版本的标准中是否存在与此存储类说明符相同的内容，或者是由编译器负责？

I have read (here, for example) that the register keyword is deprecated in C++ 11. As such, is there an equivalent to this storage-class specifier in the newer versions of the standard, or is it taken care by the compiler?

推荐答案

我们可以在 www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4193.html#809\">缺陷报告809：弃用注册表关键字，说明（强调我的）：

We can find the rationale for depreciating register in defect report 809: Deprecation of the register keyword which says (emphasis mine):

register关键字的功能非常少，不提供
通常被忽略。它应该是
在这个版本的标准中弃用，释放保留名称
在未来的标准中使用，很像汽车已被重用这个
时间同样无用。

The register keyword serves very little function, offering no more than a hint that a note says is typically ignored. It should be deprecated in this version of the standard, freeing the reserved name up for use in a future standard, much like auto has been re-used this time around for being similarly useless.

删除C ++ 17的注册表 在Lenexa会议上批准，但仍保留供将来使用。

The removal of register for C++17 was approved in the Lenexa meeting but it is still reserved for future use.

register关键字在2011 C ++标准中已弃用，其
效果已在语言中隐含。它仍保留为标准未来使用的
，是删除其残留的
规范的时间。

The register keyword was deprecated in the 2011 C++ standard, as its effect was already implicit in the language. It remains reserved for future use by the standard, and is time to remove its vestigial specification.

由于 as-if规则，编译器只需模拟 observable行为，因此优化器可以通过 as-if规则选择在寄存器中保存变量，如果它不会影响可观察的行为，并且可能在大多数情况下会做出更好的选择，因为它通常有更多信息。

Because of the as-if rule the compiler only has to emulate the observable behavior of the program and therefore the optimizer can via the as-if rule choose to keep a variable in a register if it won't effect observable behavior and presumably will in most cases make better choices since it usually has more information.

有关参考，请参阅 gcc 邮件列表中的registerC关键字的角色？，回复在帖子中说：

For reference also see role of "register" C keyword? from the gcc mailing list, one of the replies in the thread says:

register关键字在gcc中影响了寄存器分配
。

I don't think the "register" keyword ever affected register allocation in gcc. For that you have to go back to compilers of the 1970s.

注册关键字在gcc
扩展中仍然有用处：gcc uses它与asm组合实现寄存器
变量。

The register keyword does still have a use, though, in a gcc extension: gcc uses it in combination with asm to implement register variables.

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