使用SSE内在函数编译一个简单的c ++程序

问题描述

我是新的SSE说明，我试图从这个网站学习他们：

I am new to the SSE instructions and I was trying to learn them from this site:http://www.codeproject.com/Articles/4522/Introduction-to-SSE-Programming

我是在Ubuntu 10.10上使用GCC编译器与Intel Core i7 960 CPU

I am using the GCC compiler on Ubuntu 10.10 with an Intel Core i7 960 CPU

这是一个基于我尝试的文章的代码：

Here is a code based on the article which I attempted:

对于长度为ARRAY_SIZE的两个数组，它计算

For two arrays of length ARRAY_SIZE it calculates

fResult [i] = sqrt（fSource1 [i] * fSource1 [i ] + fSource2 [i] * fSource2 [i]）+ 0.5

以下是代码

#include <iostream>
#include <iomanip>
#include <ctime>
#include <stdlib.h>
#include <xmmintrin.h> // Contain the SSE compiler intrinsics
#include <malloc.h>
void myssefunction(
          float* pArray1,                   // [in] first source array
          float* pArray2,                   // [in] second source array
          float* pResult,                   // [out] result array
          int nSize)                        // [in] size of all arrays
{
    int nLoop = nSize/ 4;

    __m128 m1, m2, m3, m4;

    __m128* pSrc1 = (__m128*) pArray1;
    __m128* pSrc2 = (__m128*) pArray2;
    __m128* pDest = (__m128*) pResult;


    __m128 m0_5 = _mm_set_ps1(0.5f);        // m0_5[0, 1, 2, 3] = 0.5

    for ( int i = 0; i < nLoop; i++ )
    {
        m1 = _mm_mul_ps(*pSrc1, *pSrc1);        // m1 = *pSrc1 * *pSrc1
        m2 = _mm_mul_ps(*pSrc2, *pSrc2);        // m2 = *pSrc2 * *pSrc2
        m3 = _mm_add_ps(m1, m2);                // m3 = m1 + m2
        m4 = _mm_sqrt_ps(m3);                   // m4 = sqrt(m3)
        *pDest = _mm_add_ps(m4, m0_5);          // *pDest = m4 + 0.5

        pSrc1++;
        pSrc2++;
        pDest++;
    }
}

int main(int argc, char *argv[])
{
  int ARRAY_SIZE = atoi(argv[1]);
  float* m_fArray1 = (float*) _aligned_malloc(ARRAY_SIZE * sizeof(float), 16);
  float* m_fArray2 = (float*) _aligned_malloc(ARRAY_SIZE * sizeof(float), 16);
  float* m_fArray3 = (float*) _aligned_malloc(ARRAY_SIZE * sizeof(float), 16);

  for (int i = 0; i < ARRAY_SIZE; ++i)
    {
      m_fArray1[i] = ((float)rand())/RAND_MAX;
      m_fArray2[i] = ((float)rand())/RAND_MAX;
    }

  myssefunction(m_fArray1 , m_fArray2 , m_fArray3, ARRAY_SIZE);

  _aligned_free(m_fArray1);
   _aligned_free(m_fArray2);
   _aligned_free(m_fArray3);

  return 0;
}

我收到以下压缩错误

[Programming/SSE]$ g++ -g -Wall -msse sseintro.cpp
sseintro.cpp: In function ‘int main(int, char**)’:
sseintro.cpp:41: error: ‘_aligned_malloc’ was not declared in this scope
sseintro.cpp:53: error: ‘_aligned_free’ was not declared in this scope
[Programming/SSE]$

我在哪里搞乱？我缺少一些头文件？我似乎包含了所有相关的内容。

Where am I messing up? Am I missing some header files? I seem to have included all the relevant ones.

推荐答案

和是Microsoft主题。使用或在Linux上等。对于Mac OS X，您可以使用malloc，因为它总是16字节对齐。对于可移植SSE代码，您通常希望实现用于对齐内存分配的封装函数，例如

_aligned_malloc and _aligned_free are Microsoft-isms. Use posix_memalign or memalign on Linux et al. For Mac OS X you can just use malloc, as it is always 16 byte aligned. For portable SSE code you generally want to implement wrapper functions for aligned memory allocations, e.g.

void * malloc_simd(const size_t size)
{
#if defined WIN32           // WIN32
    return _aligned_malloc(size, 16);
#elif defined __linux__     // Linux
    return memalign(16, size);
#elif defined __MACH__      // Mac OS X
    return malloc(size);
#else                       // other (use valloc for page-aligned memory)
    return valloc(size);
#endif
}

实施 free_simd 作为练习留给读者。

Implementation of free_simd is left as an exercise for the reader.

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