标准委员会关心的异乎寻常的架构 [英] Exotic architectures the standards committees care about

问题描述

我知道 C 和 C++ 标准保留了语言实现的许多方面，只是因为如果存在具有其他特征的架构，那么为它编写符合标准的编译器将非常困难或不可能.

I know that the C and C++ standards leave many aspects of the language implementation-defined just because if there is an architecture with other characteristics, it would be very difficult or impossible to write a standard conforming compiler for it.

我知道 40 年前，任何计算机都有自己独特的规格.但是，我不知道今天使用的任何架构:

I know that 40 years ago any computer had its own unique specification. However, I don't know of any architectures used today where:

• CHAR_BIT != 8
• signed 不是二进制补码(我听说 Java 有这个问题).
• 浮点不符合 IEEE 754(我的意思是不在 IEEE 754 二进制编码中").

• CHAR_BIT != 8
• signed is not two's complement (I heard Java had problems with this one).
• Floating point is not IEEE 754 compliant ( I meant "not in IEEE 754 binary encoding").

我问的原因是，我经常向人们解释说，C++ 不强制要求任何其他低级方面(如固定大小的类型)是件好事^†.这很好，因为与其他语言"不同，它使您的代码在正确使用时可移植(因为它可以移植到更多架构而无需模拟机器的低级方面，例如符号+幅度架构上的二进制补码算法).但我很难过自己无法指出任何具体的架构.

The reason I'm asking is that I often explain to people that it's good that C++ doesn't mandate any other low-level aspects like fixed sized types^†. It's good because unlike 'other languages' it makes your code portable when used correctly ( because it can be ported to more architectures without requiring emulation of low-level aspects of the machine, like e.g. two's complement arithmetic on sign+magnitude architecture). But I feel bad that I cannot point to any specific architecture myself.

所以问题是:哪些架构具有上述特性?

So the question is: what architectures exhibit the above properties?

† uint*_ts 是可选的.

推荐答案

看看这个

Unisys ClearPath Dorado 服务器

为尚未迁移所有 Univac 软件的用户提供向后兼容性.

offering backward compatibility for people who have not yet migrated all their Univac software.

关键点:

• 36 位字
• CHAR_BIT == 9
• 补码
• 72 位非 IEEE 浮点数
• 代码和数据的独立地址空间
• 字地址
• 没有专用的堆栈指针

虽然不知道他们是否提供 C++ 编译器，但他们可以.

Don't know if they offer a C++ compiler though, but they could.

现在他们的 C 手册最新版本的链接已经浮出水面:

And now a link to a recent edition of their C manual has surfaced:

Unisys C 编译器编程参考手册

第 4.5 节有一个包含 9、18、36 和 72 位的数据类型表.

Section 4.5 has a table of data types with 9, 18, 36, and 72 bits.

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