矢量类库：解决使用 vec4d 时的问题

发布于 2025-01-13 00:26:24 字数 739 浏览 0 评论 0原文

这是一段导致我出现问题/错误的简化代码（Vec4d 来自 Agner Fog 库 VCL）

#define AVX256_ALIGNED_MALLOC(type,size) (type *)_aligned_malloc(size * sizeof(type),32)
#define AVX256_FREE(ptr) _aligned_free(ptr)

int N = 1024;
std::vector<double> A(N);
double* Aaligned = AVX256_ALIGNED_MALLOC(double, N);
memcpy(Aaligned, &A[0], N * sizeof(double));

int N4=N>>2;

for(size_t i = 4; i <N4-4; ++i)
{
    //....
    ... = ((Vec4d*)(Aaligned - 1))[i] + ((Vec4d*)(Aaligned))[i] + ((Vec4d*)(Aaligned + 1))[i];
}

AVX256_FREE(Aaligned);

如果我清楚我可以使用，

((Vec4d*)(Aaligned))[i]

您能否确认我不能使用

((Vec4d*)(Aaligned-1))[i]

或 ((Vec4d*)(Aaligned+1))[i] 有什么提示吗？非常感谢。吕克

原文

here a piece of simplified code that causes me a problem/error (Vec4d is coming from the Agner Fog library VCL)

#define AVX256_ALIGNED_MALLOC(type,size) (type *)_aligned_malloc(size * sizeof(type),32)
#define AVX256_FREE(ptr) _aligned_free(ptr)

int N = 1024;
std::vector<double> A(N);
double* Aaligned = AVX256_ALIGNED_MALLOC(double, N);
memcpy(Aaligned, &A[0], N * sizeof(double));

int N4=N>>2;

for(size_t i = 4; i <N4-4; ++i)
{
    //....
    ... = ((Vec4d*)(Aaligned - 1))[i] + ((Vec4d*)(Aaligned))[i] + ((Vec4d*)(Aaligned + 1))[i];
}

AVX256_FREE(Aaligned);

If it is clear to me that I'am allowed to use