[v4,2/4] hash: optimize compare signature for NEON
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Commit Message
Upon a successful comparison, NEON sets all the bits in the lane to 1
We can skip shifting by simply masking with specific masks.
Signed-off-by: Yoan Picchi <yoan.picchi@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: Nathan Brown <nathan.brown@arm.com>
---
lib/hash/rte_cuckoo_hash.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
@@ -1871,19 +1871,17 @@ compare_signatures_dense(uint32_t *prim_hash_matches, uint32_t *sec_hash_matches
/* For match mask every bits indicates the match */
switch (sig_cmp_fn) {
case RTE_HASH_COMPARE_NEON: {
- uint16x8_t vmat, vsig, x;
- int16x8_t shift = {0, 1, 2, 3, 4, 5, 6, 7};
+ uint16x8_t vmat, x;
+ const uint16x8_t mask = {0x1, 0x2, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80};
+ const uint16x8_t vsig = vld1q_dup_u16((uint16_t const *)&sig);
- vsig = vld1q_dup_u16((uint16_t const *)&sig);
/* Compare all signatures in the primary bucket */
- vmat = vceqq_u16(vsig,
- vld1q_u16((uint16_t const *)prim_bkt->sig_current));
- x = vshlq_u16(vandq_u16(vmat, vdupq_n_u16(0x0001)), shift);
+ vmat = vceqq_u16(vsig, vld1q_u16((uint16_t const *)prim_bkt->sig_current));
+ x = vandq_u16(vmat, mask);
*prim_hash_matches = (uint32_t)(vaddvq_u16(x));
/* Compare all signatures in the secondary bucket */
- vmat = vceqq_u16(vsig,
- vld1q_u16((uint16_t const *)sec_bkt->sig_current));
- x = vshlq_u16(vandq_u16(vmat, vdupq_n_u16(0x0001)), shift);
+ vmat = vceqq_u16(vsig, vld1q_u16((uint16_t const *)sec_bkt->sig_current));
+ x = vandq_u16(vmat, mask);
*sec_hash_matches = (uint32_t)(vaddvq_u16(x));
}
break;