SSE:将__m128转换为float

Question

我有以下C代码:

__m128 pSrc1 = _mm_set1_ps(4.0f);
__m128 pDest;
int i;
for (i=0;i<100;i++) {
       m1 = _mm_mul_ps(pSrc1, pSrc1);      
       m2 = _mm_mul_ps(pSrc1, pSrc1);        
       m3 = _mm_add_ps(m1, m2);             
       pDest = _mm_add_ps(m3, m3); 
}

float *arrq = (float*) pDest;

直到for循环结束的所有内容都有效.我现在要做的是将__m128类型转换回float.因为它存储了4个浮点数,我认为我很容易将其转换为浮动*.我究竟做错了什么？(这是一个测试代码,所以不要怀疑).我基本上尝试了所有可能的转换.谢谢你的帮助.

Answer 1

您需要使用_mm_store_ps它将它重新放回浮点数.码:

// result must be 16-byte aligned
float result [4];
_mm_store_ps (result, pDest);

// If result is not 16-byte aligned, use _mm_storeu_ps
// On modern CPUs this is just as fast as _mm_store_ps if
// result is 16-byte aligned, but works in all other cases as well
_mm_storeu_ps (result, pDest);