添加SSE寄存器的组件 [英] adding the components of an SSE register

问题描述

我想添加一个SSE寄存器的四个组件来获得一个浮点数。这是我现在这样做：

  float a [4]; 
 _mm_storeu_ps（a，foo128）; 
 float x = a [0] + a [1] + a [2] + a [3]; 
  

是否有一个SSE指令可以直接实现这个？

HADDPS SSE3指令或其编译器固有的 _mm_hadd_ps ，

例如，请参阅 http：// msdn如果你有两个寄存器v1和v2：

/ p>

  v = _mm_hadd_ps（v1，v2）; 
 v = _mm_hadd_ps（v，v）; 
 
 
 
 
 $ b现在，v [0]包含了v1的分量之和，v [1]的v2组件。
 
I want to add the four components of an SSE register to get a single float. This is how I do it now:
float a[4];
_mm_storeu_ps(a, foo128);
float x = a[0] + a[1] + a[2] + a[3];
Is there an SSE instruction that directly achieves this?
解决方案
You could probably use the HADDPS SSE3 instruction, or its compiler intrinsic _mm_hadd_ps, 

For example, see http://msdn.microsoft.com/en-us/library/yd9wecaa(v=vs.80).aspx

If you have two registers v1 and v2 :
v = _mm_hadd_ps(v1, v2);
v = _mm_hadd_ps(v, v);
Now, v[0] contains the sum of v1's components, and v[1] contains the sum of v2's components.

                        
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