__lasx_xvmulwod_w_hu

LASX intrinsic · group: Integer Computation

Synopsis

__m256i __lasx_xvmulwod_w_hu (__m256i a, __m256i b)
#include <lasxintrin.h>
Instruction: xvmulwod.w.hu xr, xr, xr
CPU Flags: LASX

Description

Multiply the odd-positioned unsigned 16-bit elements in a and the corresponding unsigned 16-bit elements in b, extending both to 32-bit, and save the 32-bit result in dst.

Operation

for (int i = 0; i < 8; i++) {
  dst.word[i] = (u32)(u16)a.half[2 * i + 1] * (u32)(u16)b.half[2 * i + 1];
}

// Expands to:

if (0) {
  dst.word[0] = ((u32)((u16)a.half[1])) * ((u32)((u16)b.half[1]));
  dst.word[1] = ((u32)((u16)a.half[3])) * ((u32)((u16)b.half[3]));
  dst.word[2] = ((u32)((u16)a.half[5])) * ((u32)((u16)b.half[5]));
  dst.word[3] = ((u32)((u16)a.half[7])) * ((u32)((u16)b.half[7]));
  dst.word[4] = ((u32)((u16)a.half[9])) * ((u32)((u16)b.half[9]));
  dst.word[5] = ((u32)((u16)a.half[11])) * ((u32)((u16)b.half[11]));
  dst.word[6] = ((u32)((u16)a.half[13])) * ((u32)((u16)b.half[13]));
  dst.word[7] = ((u32)((u16)a.half[15])) * ((u32)((u16)b.half[15]));
}

Tested on real machine.

Latency and Throughput

CPU	µarch	Latency	Throughput (IPC)
3C5000	LA464	4	2
3A6000	LA664	4	2
3C6000	LA664	4	2

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