Is Reinterpret_casting Between Hardware SIMD Vector Pointers and Corresponding Types Undefined Behavior?

Can reinterpret_cast between hardware SIMD vector pointer and the corresponding type cause undefined behavior?

No, it is not undefined behavior to reinterpret_cast between a hardware SIMD vector pointer and the corresponding type. This is because Intel's intrinsics define vector pointers like __m256 as being allowed to alias anything else, the same way ISO C defines char as being allowed to alias.

Does it violate strict aliasing rules?

No, it does not violate strict aliasing rules. This is because the vector pointer is defined with a may_alias attribute, which allows it to alias other types.

Is there only one defined way of intrinsic:

No, there is not only one defined way of intrinsic. You can also use intrinsics like _mm256_load_ps() and _mm256_store_ps() to load and store vector data from memory.

In summary, reinterpret_cast between hardware SIMD vector pointer and the corresponding type is allowed, does not violate strict aliasing rules, and can be done in multiple ways, depending on the specific requirements of your code.

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