__lsx_vfrstp_h

LSX intrinsic · group: Misc

Synopsis

__m128i __lsx_vfrstp_h (__m128i a, __m128i b, __m128i c)
#include <lsxintrin.h>
Instruction: vfrstp.h vr, vr, vr
CPU Flags: LSX

Description

For each 128-bit lane, find the first negative 16-bit element in b. Write its index into the lane of a selected by the first element of the corresponding lane of c modulo 8, or write the maximum valid index plus one if no such element exists. Other elements of a remain unchanged.

Operation

for (int i = 0; i < 8; i++) {
  dst.half[i] = a.half[i];
}
int i;
for (i = 0; i < 8; i++) {
  if ((s16)b.half[i] < 0) {
    break;
  }
}
dst.half[c.half[0] % 8] = i;

Tested on real machine.

Latency and Throughput

CPU	µarch	Latency	Throughput (IPC)
3C5000	LA464	2	2
3A6000	LA664	2	2
3C6000	LA664	2	2
2K1000LA	LA264	2	1
2K3000	LA364E	1	1

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