From: Evandro Menezes <e.menezes@samsung.com>
To: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Cc: "gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>, nd <nd@arm.com>
Subject: Re: [AArch64] Emit square root using the Newton series
Date: Thu, 10 Mar 2016 22:15:00 -0000 [thread overview]
Message-ID: <56E1F1FB.6070405@samsung.com> (raw)
In-Reply-To: <AM3PR08MB00886A32AE872304290F0B1483B40@AM3PR08MB0088.eurprd08.prod.outlook.com>
On 03/10/16 13:10, Wilco Dijkstra wrote:
> frsqrte s1, s0
> fmul s2, s1, s1
> frsqrts s2, s0, s2
> fcmp s0, 0.0
> fmul s1, s1, s2
> fmul s2, s1, s1
> fmul s1, s0, s1
> frsqrts s2, s0, s2
> fcsel s1, s0, s1, eq
> fmul s0, s1, s2
That's what I had in mind too, but around the approximation for x^-1/2
and using masks for vector cases thusly:
fcmne v3.4s, v0.4s, #0.0
frsqrte v1.4s, v0.4s
fmul v2.4s, v1.4s, v1.4s
frsqrts v2.4s, v0.4s, v2.4s
fmul v1.4s, v1.4s, v2.4s
fmul v2.4s, v1.4s, v1.4s
frsqrts v2.4s, v0.4s, v2.4s
fmul v1.4s, v1.4s, v2.4s
and v1.4s, v3.4s
fmul v0.4s, v1.4s, v0.4s
Thanks,
--
Evandro Menezes
next prev parent reply other threads:[~2016-03-10 22:15 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <AM3PR08MB00886499882773F3C8B9F71D83B30@AM3PR08MB0088.eurprd08.prod.outlook.com>
[not found] ` <011d01d17a26$31b3ade0$951b09a0$@samsung.com>
2016-03-10 16:52 ` Wilco Dijkstra
2016-03-10 16:58 ` Evandro Menezes
2016-03-10 19:10 ` Wilco Dijkstra
2016-03-10 22:15 ` Evandro Menezes [this message]
2016-03-11 1:06 ` Wilco Dijkstra
2016-03-14 16:39 ` Evandro Menezes
2016-03-14 19:13 ` Wilco Dijkstra
2016-03-16 21:44 ` Evandro Menezes
2016-03-17 22:50 Evandro Menezes
2016-03-24 20:30 ` [AArch64] " Evandro Menezes
2016-04-01 22:45 ` Evandro Menezes
2016-04-04 16:32 ` Evandro Menezes
[not found] ` <DB3PR08MB008902F0F0AFA3B1F1C91511839E0@DB3PR08MB0089.eurprd08.prod.outlook.com>
2016-04-05 22:30 ` Evandro Menezes
2016-04-12 18:15 ` Evandro Menezes
2016-04-21 18:44 ` Evandro Menezes
2016-04-27 14:24 ` James Greenhalgh
2016-04-27 15:45 ` Evandro Menezes
-- strict thread matches above, loose matches on Subject: below --
2015-12-08 21:35 Evandro Menezes
2015-12-09 14:05 ` Marcus Shawcroft
2015-12-09 16:31 ` Evandro Menezes
2015-12-09 16:52 ` Kyrill Tkachov
2015-12-09 16:59 ` Evandro Menezes
2015-12-09 17:03 ` Kyrill Tkachov
2015-12-09 17:16 ` Kyrill Tkachov
2015-12-09 18:50 ` Evandro Menezes
2015-12-10 10:30 ` Kyrill Tkachov
2016-02-23 0:50 ` Evandro Menezes
2016-02-26 15:00 ` James Greenhalgh
2016-02-26 23:42 ` Evandro Menezes
2016-02-26 23:46 ` Evandro Menezes
2016-02-16 20:56 ` Evandro Menezes
2016-03-04 0:22 ` Evandro Menezes
2016-03-08 22:08 ` Evandro Menezes
2016-03-08 22:18 ` Evandro Menezes
2016-03-08 22:20 ` Evandro Menezes
2016-03-16 19:45 ` Evandro Menezes
2016-03-17 14:55 ` James Greenhalgh
2016-03-17 16:25 ` Evandro Menezes
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