What's the most efficient way to load and extract 32 bit integer values from a 128 bit SSE vector?

Question

I\'m trying to optimize my code using SSE intrinsics but am running into a problem where I don\'t know of a good way to extract the integer values from a vector after I\'ve

Answer 1

_mm_extract_epi32

The extract intrinsics is indeed the best option but if you need to support SSE2, I'd recommend this:

inline int get_x(const __m128i& vec){return _mm_cvtsi128_si32 (vec);}
inline int get_y(const __m128i& vec){return _mm_cvtsi128_si32 (_mm_shuffle_epi32(vec,0x55));}
inline int get_z(const __m128i& vec){return _mm_cvtsi128_si32 (_mm_shuffle_epi32(vec,0xAA));}
inline int get_w(const __m128i& vec){return _mm_cvtsi128_si32 (_mm_shuffle_epi32(vec,0xFF));}

I've found that if you reinterpret_cast/union the vector to any int[4] representation the compiler tends to flush things back to memory (which may not be that bad) and reads it back as an int, though I haven't looked at the assembly to see if the latest versions of the compilers generate better code.