From: Bruce Richardson <bruce.richardson@intel.com>
To: Jieqiang Wang <jieqiang.wang@arm.com>
Cc: Yipeng Wang <yipeng1.wang@intel.com>,
Sameh Gobriel <sameh.gobriel@intel.com>,
Vladimir Medvedkin <vladimir.medvedkin@intel.com>,
Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>,
Dharmik Thakkar <dharmik.thakkar@arm.com>, <dev@dpdk.org>,
<nd@arm.com>, <stable@dpdk.org>,
Feifei Wang <feifei.wang2@arm.com>,
Ruifeng Wang <ruifeng.wang@arm.com>
Subject: Re: [PATCH v3] hash: fix SSE comparison
Date: Mon, 9 Oct 2023 15:33:23 +0100 [thread overview]
Message-ID: <ZSQPMz35BCZFJRXm@bricha3-MOBL.ger.corp.intel.com> (raw)
In-Reply-To: <20231007073634.3458294-1-jieqiang.wang@arm.com>
On Sat, Oct 07, 2023 at 03:36:34PM +0800, Jieqiang Wang wrote:
> __mm_cmpeq_epi16 returns 0xFFFF if the corresponding 16-bit elements are
> equal. In original SSE2 implementation for function compare_signatures,
> it utilizes _mm_movemask_epi8 to create mask from the MSB of each 8-bit
> element, while we should only care about the MSB of lower 8-bit in each
> 16-bit element.
> For example, if the comparison result is all equal, SSE2 path returns
> 0xFFFF while NEON and default scalar path return 0x5555.
> Although this bug is not causing any negative effects since the caller
> function solely examines the trailing zeros of each match mask, we
> recommend this fix to ensure consistency with NEON and default scalar
> code behaviors.
>
> Fixes: c7d93df552c2 ("hash: use partial-key hashing")
> Cc: stable@dpdk.org
>
> v2:
> 1. Utilize scalar mask instead of vector mask to save extra loads (Bruce)
>
> v3:
> 1. Fix coding style warnings
>
> Signed-off-by: Feifei Wang <feifei.wang2@arm.com>
> Signed-off-by: Jieqiang Wang <jieqiang.wang@arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
next prev parent reply other threads:[~2023-10-09 14:33 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-06 2:31 [PATCH] " Jieqiang Wang
2023-09-29 15:32 ` David Marchand
2023-10-02 10:39 ` Bruce Richardson
2023-10-07 6:41 ` 回复: " Jieqiang Wang
2023-10-07 7:15 ` [PATCH v2] " Jieqiang Wang
2023-10-07 7:36 ` [PATCH v3] " Jieqiang Wang
2023-10-09 14:33 ` Bruce Richardson [this message]
2023-10-10 9:50 ` David Marchand
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