From: Marcus Shawcroft <marcus.shawcroft@gmail.com>
To: Evandro Menezes <e.menezes@samsung.com>
Cc: "gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>,
Marcus Shawcroft <Marcus.Shawcroft@arm.com>,
Kyrill Tkachov <kyrylo.tkachov@arm.com>
Subject: Re: [PATCH][AArch64] Replace insn to zero up DF register
Date: Fri, 30 Oct 2015 10:26:00 -0000 [thread overview]
Message-ID: <CAFqB+Pwu_s+metkuMdXx84EVFXfXo3eSr-YSPRpk-81MsXuZnQ@mail.gmail.com> (raw)
In-Reply-To: <56257F53.2000905@samsung.com>
On 20 October 2015 at 00:40, Evandro Menezes <e.menezes@samsung.com> wrote:
> In the existing targets, it seems that it's always faster to zero up a DF
> register with "movi %d0, #0" instead of "fmov %d0, xzr".
>
> This patch modifies the respective pattern.
Hi Evandro,
This patch changes the generic, u architecture independent instruction
selection. The ARM ARM (C3.5.3) makes a specific recommendation about
the choice of instruction in this situation and the current
implementation in GCC follows that recommendation. Wilco has also
picked up on this issue he has the same patch internal to ARM along
with an ongoing discussion with ARM architecture folk regarding this
recommendation. I'm reluctant to take this patch right now on the
basis that it runs contrary to ARM ARM recommendation pending the
conclusion of Wilco's discussion with ARM architecture folk.
Cheers
/Marcus
next prev parent reply other threads:[~2015-10-30 10:24 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-19 23:41 Evandro Menezes
2015-10-19 23:52 ` Andrew Pinski
2015-10-20 0:33 ` Andrew Pinski
2015-10-20 14:46 ` Andrew Pinski
2015-10-28 18:49 ` Evandro Menezes
2015-10-30 10:26 ` Marcus Shawcroft [this message]
2015-11-09 22:59 ` Evandro Menezes
2015-12-03 21:01 ` Evandro Menezes
2015-11-19 22:01 ` Evandro Menezes
2015-12-16 21:30 ` Evandro Menezes
2016-01-13 0:06 ` Evandro Menezes
2016-01-22 13:52 Wilco Dijkstra
2016-01-27 23:14 ` Evandro Menezes
2016-02-26 12:37 ` Wilco Dijkstra
2016-02-26 22:43 ` Evandro Menezes
2016-02-29 18:07 ` Wilco Dijkstra
2016-02-29 23:11 ` Evandro Menezes
2016-03-01 19:02 ` Wilco Dijkstra
2016-03-01 19:08 ` Evandro Menezes
2016-03-09 21:36 ` Evandro Menezes
2016-03-10 13:23 ` James Greenhalgh
2016-03-10 16:27 ` Evandro Menezes
2016-03-10 16:32 ` Evandro Menezes
2016-03-10 16:37 ` James Greenhalgh
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