Check XMM register for all zeroes

Question

Is there a way to check if all bits/bytes/words etc. in a __m128i variable are 0?
In my app I have to check if all integers packed in a in a __m128i variable are zeroes

Answer 1

_mm_testz_si128 is SSE4.1 which isn't supported on some CPUs (e.g. Intel Atom, AMD Phenom)

Here is an SSE2-compatible variant

inline bool isAllZeros(__m128i xmm) {
    return _mm_movemask_epi8(_mm_cmpeq_epi8(xmm, _mm_setzero_si128())) == 0xFFFF;
}

Answer 2

Like Paul R commented to my original post:

"You don't need to initialise a dummy argument for the second parameter of PTEST, i.e. instead of _mm_testz_si128(idata, _mm_set1_epi32(0xFFFF)) you can just test a value against itself."

ptest does the entire job with one instruction.

This helped.