From: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
To: Evandro Menezes <e.menezes@samsung.com>,
GCC Patches <gcc-patches@gcc.gnu.org>
Cc: James Greenhalgh <James.Greenhalgh@arm.com>,
Andrew Pinski <pinskia@gmail.com>, nd <nd@arm.com>
Subject: Re: [AArch64] Emit division using the Newton series
Date: Fri, 01 Apr 2016 21:22:00 -0000 [thread overview]
Message-ID: <AM3PR08MB00884DBC29E8F0651E1ECEC6839A0@AM3PR08MB0088.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <56FED036.2070405@samsung.com>
Evandro Menezes wrote:
> > The division variant should use the same latency reduction trick I mentioned for sqrt.
>
> I don't think that it applies here, since it doesn't have to deal with
> special cases.
No it applies as it's exactly the same calculation: x * rsqrt(y) and x * recip(y). In both
cases you don't need the final result of rsqrt(y) or recip(y), avoiding a multiply.
Given these sequences are high latency this saving is actually quite important.
Wilco
next prev parent reply other threads:[~2016-04-01 21:22 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-17 21:14 Evandro Menezes
2016-03-23 16:24 ` Evandro Menezes
2016-03-23 16:25 ` Evandro Menezes
2016-03-31 22:23 ` Evandro Menezes
2016-04-01 13:58 ` Wilco Dijkstra
2016-04-01 19:47 ` Evandro Menezes
2016-04-01 21:22 ` Wilco Dijkstra [this message]
2016-04-01 21:56 ` Evandro Menezes
2016-04-01 22:46 ` Wilco Dijkstra
2016-04-01 22:52 ` Evandro Menezes
2016-04-04 19:06 ` Evandro Menezes
2016-04-12 18:15 ` Evandro Menezes
2016-04-21 18:44 ` Evandro Menezes
2016-04-27 14:16 ` James Greenhalgh
2016-04-27 14:44 ` Wilco Dijkstra
2016-04-27 15:43 ` Evandro Menezes
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