c++ - __mm128 的向量不会 push_back()

Question

这个简单的 SSE 代码：

#include <vector>
#include <emmintrin.h>

int main() {
    std::vector<__m128> blah;
    blah.push_back(__m128());
}

在 MSVC 10 上崩溃，在0xffffffff.

可能出了什么问题？

Answer 1

A std::vector does not allocate specially aligned memory, which __m128 needs to store it's data. You will have to either swap out the allocator, or replace it with an array of 4 floats and then perform an unaligned load or copy out to an aligned location every time you access the vector.