__lasx_xvmaddwev_q_d
LASX intrinsic · group: Integer Computation
Synopsis
__m256i __lasx_xvmaddwev_q_d (__m256i a, __m256i b, __m256i c)
#include <lasxintrin.h>
Instruction: xvmaddwev.q.d xr, xr, xr
CPU Flags: LASX
Description
Multiply the even-positioned signed 64-bit elements in b and the corresponding signed 64-bit elements in c, extending both to 128-bit, and add the product to the 128-bit elements in a.
Operation
for (int i = 0; i < 2; i++) {
dst.qword[i] =
(s128)(s64)b.dword[2 * i] * (s128)(s64)c.dword[2 * i] + (s128)a.qword[i];
}
// Expands to:
if (0) {
dst.qword[0] = (((s128)((s64)b.dword[0])) * ((s128)((s64)c.dword[0]))) +
((s128)a.qword[0]);
dst.qword[1] = (((s128)((s64)b.dword[2])) * ((s128)((s64)c.dword[2]))) +
((s128)a.qword[1]);
}
Tested on real machine.
Latency and Throughput
| CPU | µarch | Latency | Throughput (IPC) |
|---|---|---|---|
| 3C5000 | LA464 | 7 | 1.14 |
| 3A6000 | LA664 | 7 | 1.14 |
| 3C6000 | LA664 | 7 | 1.14 |