CODEWITHSUNDEEP
x86ssesimd
paseena
paseena

Reputation: 4315

Is it possible to vectorize a multiplication in VC++ without SSE4?

I want to vectorize a multiplication operation. I tried using _mm_mul_epi32, but my CPU has only support for the "MMX, SSE (1,2,3,3S), EM64T" instruction.

Can someone please tell if I can try another function?

Upvotes: 4

Views: 351

Answers (1)

Paul R
Paul R

Reputation: 212929

It depends on the range of your multiplicands - it they fit within 16 bits then there are a number of 16 x 16 bit multiple SSE instructions available prior to SSE4 (e.g. mm_madd_epi16, mm_mulhi_epi16, mm_mullo_epi16, mm_mulhrs_epi16, etc).

If you need 32 bit operands but they are unsigned then you can use mm_mul_epu32.

Alternatively you may convert to float, and use _mm_mul_ps (integer <-> float conversion in SSE is quite efficient, and the cost may be justified if it gets you a 4x SIMD throughput improvement).

Upvotes: 4

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