__lsx_vmaddwev_w_h
LSX intrinsic · group: Integer Computation
Synopsis
__m128i __lsx_vmaddwev_w_h (__m128i a, __m128i b, __m128i c)
#include <lsxintrin.h>
Instruction: vmaddwev.w.h vr, vr, vr
CPU Flags: LSX
Description
Multiply the even-positioned signed 16-bit elements in b and the corresponding signed 16-bit elements in c, extending both to 32-bit, and add the product to the 32-bit elements in a.
Operation
for (int i = 0; i < 4; i++) {
dst.word[i] =
(s32)(s16)b.half[2 * i] * (s32)(s16)c.half[2 * i] + (s32)a.word[i];
}
// Expands to:
if (0) {
dst.word[0] =
(((s32)((s16)b.half[0])) * ((s32)((s16)c.half[0]))) + ((s32)a.word[0]);
dst.word[1] =
(((s32)((s16)b.half[2])) * ((s32)((s16)c.half[2]))) + ((s32)a.word[1]);
dst.word[2] =
(((s32)((s16)b.half[4])) * ((s32)((s16)c.half[4]))) + ((s32)a.word[2]);
dst.word[3] =
(((s32)((s16)b.half[6])) * ((s32)((s16)c.half[6]))) + ((s32)a.word[3]);
}
Tested on real machine.
Latency and Throughput
| CPU | µarch | Latency | Throughput (IPC) |
|---|---|---|---|
| 3C5000 | LA464 | 4 | 2 |
| 3A6000 | LA664 | 4 | 2 |
| 3C6000 | LA664 | 4 | 2 |
| 2K1000LA | LA264 | 4 | 1 |
| 2K3000 | LA364E | 4 | 1 |