We have some intentional unaligned access in vector_algorithms.cpp. Some occurrences are marked:

There may be some unmarked occurrences as well.

I can think of a few fixing that

1. memcpy. The usual way, but it makes debug codegen slightly worse. #pragma intrinsic can partly mitigate debug codegen worsening.
2. __builtin_bit_cast. Perfect codegen, ugly construct:

   unsigned long long cast(void* p) {
      return __builtin_bit_cast(unsigned long long, *reinterpret_cast<unsigned char(*)[8]>(p));
   }
   

There's a bug reported by @frederick-vs-ja as DevCom-10974125, now Fixed - Pending Release. Workaround is to save the reinterpret_cast result to a variable.

3. __builtin_bit_cast wrappers std::_Bit_cast or std::bit_cast. Same as the previous, plus function call in debug. Avoids the bug.

The memcpy approach has already been used in some more recent parts, so if we prefer other approach, we may want to revisit that as well: