保留执行管道 [英] Preserving the Execution pipeline

问题描述

常常检查返回类型的错误。但是，将继续执行的代码可以以不同的方式指定。

  if（！ret）
 { 
 doNoErrorCode（）; 
} 
 exit（1）; 
  

或

  if（ret）
 {
 exit（1）; 
} 
 doNoErrorCode（）; 
 

单向重量级CPU可以使用简单的统计数据推测近邻/用于分支推测（-2，-1,0，+ 1，+ 2）的4位机制，其中零是未知的，2将被认为是真正的分支。

考虑到上面的简单技术，我的问题是关于如何构造代码。我假设在主要编译器和主要架构之间必须有一个约定。这是我的两个问题

1. 当代码不是经常访问的循环时，布尔值在管道填充时？


2. 关于分支的猜测必须以true或false或零开头（管道必须填充某些东西）。

这种行为在不同的CPU之间是不同的，编译器经常重新排序指令。
您可以在这些手册中找到所需的所有信息： http://agner.org/optimize/ 。





在我看来，发现的唯一方法是读取编译器生成的汇编代码。




Return types are frequently checked for errors. But, the code that will continue to execute may be specified in different ways.

if(!ret)
{
   doNoErrorCode();
}
exit(1);

or

if(ret)
{
   exit(1);
}
doNoErrorCode();

One way heavyweight CPU's can speculate about the branches taken in near proximity/locality using simple statistics - I studied a 4-bit mechanism for branch speculation (-2,-1,0,+1,+2) where zero is unknown and 2 will be considered a true branch.

Considering the simple technique above, my questions are about how to structure code. I assume that there must be a convention among major compilers and major architectures. These are my two questions

1. When the code isn't an often-visited loop which boolean value is biased for when the pipeline is being filled ?
2. Speculation about branching must begin at either true or false or zero ( the pipeline must be filled with something). Which is it likely to be ?

解决方案

The behavior varies among CPUs, and the compiler often reorders instructions. You will find all the information you need in these manuals: http://agner.org/optimize/.

In my opinion the only way to know what happens is to read the assembly code generated by the compiler.

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