在编写由LLVM后端编译的代码时，体系结构是否重要？(When writing code compiled by LLVM backend, does architecture matter?)

 我的问题实际上比标题更普遍： 
 
 在编写代码时，体系结构在什么时候会重要，最终将编译成LLVM中间代码，然后再从那里编译到机器语言？ 
 
 
 
 假设我正在写Rust（使用LLVM作为后端）。 我是否能够自动将我的Rust代码编译到LLVM可以定位的每个体系结构（假设该机器上有一个可以运行它的操作系统）？ 
 
 
 或者Rust的标准库还没有做成“ARM兼容”，所以我不能编译到ARM，即使LLVM的目标是ARM？ 
 
 
 如果我不使用任何标准库，我的整个程序只是一个马上返回的程序呢？ 难道即使没有任何库，Rust（或你有什么）不能编译到ARM（或你有什么），即使LLVM是以它为目标的吗？ 
 
 
 如果上述所有示例都编译得很好，那么我需要做些什么才能让我的代码 
   
     在某个体系结构 
   上 
   
     中断， 
   而不是编译到某个体系结构中？ 
 
 
 相同品种的奖金问题： 
 
 
 
 比方说，标准库使用OS系统调用（这肯定是）。 系统调用时，您是否必须关心架构？ 或者，操作系统（例如，Linux）也将架构抽象出来？ 
 
 
 谢谢。 

My question is actually more general than the title:
 
At what point does the architecture matter when writing code that will eventually be compiled to LLVM intermediary code, and then from there to the machine language?
 
 
 
Let's say I'm writing Rust (which uses LLVM as a backend). Am I automatically capable of compiling my Rust code to every architecture that LLVM can target (assuming there's an OS on that machine that can run it)?
 
 
Or could it be that the Rust standard library hasn't been made "ARM compatible" yet, so I couldn't compile to ARM even if the LLVM targets it?
 
 
What if I don't use any of the standard library, my entire program is just a program that returns right away? Could it be the case that even without any libraries, Rust (or what have you) can't compile to ARM (or what have you) even if the LLVM targets it?
 
 
If all the above examples compile just fine, what do I have to do to get my code to 
   
     break on one architecture 
    not compile to a certain architecture?
 
 
Bonus question of the same variety:
 
 
 
Let's say the standard library makes use of OS system calls (which is surely does). Do you have to care about architecture when making system calls? Or does the OS (Linux, for example) abstract away architecture as well?
 
 
Thanks.

原文：https://stackoverflow.com/questions/34306069