Using STL vector with SIMD intrinsic data type

问题

As the title reads, I am trying to use STL vector with SIMD intrinsic data type. I know it is not a good practice due to the potential overhead of load/store, but I encountered a quite weird fault. Here is the code:

#include "immintrin.h"
#include <vector>
#include <stdio.h>

#define VL 8

int main () {
    std::vector<__m256> vec_1(10);
    std::vector<__m256> vec_2(10);

    float * tmp_1 = new float[VL];
    printf("vec_1[0]:\n");
    _mm256_storeu_ps(tmp_1, vec_1[0]); // seems to go as expected
    for (int i = 0; i < VL; ++i)
        printf("%f ", tmp_1[i]);
    printf("\n");
    delete tmp_1;

    float * tmp_2 = new float[VL];
    printf("vec_2[0]:\n");
    _mm256_storeu_ps(tmp_2, vec_2[0]); // segmentation fault
    for (int i = 0; i < VL; ++i)
        printf("%f ", tmp_2[i]);
    printf("\n");
    delete tmp_2;

    return 0;
}

I compiled it using g++ -O3 -g -std=c++11 -mavx2 test.cpp -o test. vec_1[0] is printed as expected (all zeros), but segmentation fault happens when it comes to vec_2[0]. I thought it was the alignment issue, but instead of _mm256_store_ps, I used _mm256_storeu_ps, which does not require alignment.

It is a Intel Haswell architecture with AVX2 extension. GCC version is 4.8.5.

Any possible clue is welcome.

来源：https://stackoverflow.com/questions/39608172/using-stl-vector-with-simd-intrinsic-data-type

标签

c++11