From: Andrew Pinski <pinskia@gmail.com>
To: Evandro Menezes <e.menezes@samsung.com>
Cc: GCC Patches <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: Tue, 20 Oct 2015 00:33:00 -0000 [thread overview]
Message-ID: <CA+=Sn1nUfBCsnFdh1WDGZCp6WYx63ns7naQUFDjECovYTWVZdQ@mail.gmail.com> (raw)
In-Reply-To: <CA+=Sn1kLDZAPBozErJtTt5HYnf3rmSyGsJhL2D8oW_v1vpCf6g@mail.gmail.com>
On Tue, Oct 20, 2015 at 7:51 AM, Andrew Pinski <pinskia@gmail.com> wrote:
> On Tue, Oct 20, 2015 at 7:40 AM, 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".
>
> I think for ThunderX 1, this change will not make a difference. So I
> am neutral on this change.
Actually depending on fmov is decoded in our pipeline, this change
might actually be worse. Currently fmov with an immediate is 1 cycle
while movi is two cycles. Let me double check how internally on how
it is decoded and if it is 1 cycle or two.
Thanks,
Andrew
>
> Thanks,
> Andrew
>
>>
>> This patch modifies the respective pattern.
>>
>> Please, commit if it's alright.
>>
>> Thank you,
>>
>> --
>> Evandro Menezes
>>
next prev parent reply other threads:[~2015-10-19 23:59 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 [this message]
2015-10-20 14:46 ` Andrew Pinski
2015-10-28 18:49 ` Evandro Menezes
2015-10-30 10:26 ` Marcus Shawcroft
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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