From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
To: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>,
"linux-snps-arc@lists.infradead.org"
<linux-snps-arc@lists.infradead.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Alexey Brodkin" <Alexey.Brodkin@synopsys.com>
Subject: Re: [PATCH 4/5] ARC: add support for DSP-enabled userspace applications
Date: Wed, 4 Mar 2020 17:58:04 +0000 [thread overview]
Message-ID: <8f5af6bd-af31-8f2f-9565-f1f505e6ba11@synopsys.com> (raw)
In-Reply-To: <BY5PR12MB4034D0D8EDD029E90642012EDEE50@BY5PR12MB4034.namprd12.prod.outlook.com>
On 3/4/20 3:51 AM, Eugeniy Paltsev wrote:
>>> + "r" (_saveto), \
>>> + "r" (_readfrom), \
>>> + "I" (_aux), \
>>> + "I" (_offt) \
>>> + : \
>>
>> AEX with "I" constraint will likely be an 8 byte instructions always. Best to give
>> compiler wiggle room with "Ir"
>
> Could you please explain how "Ir" will work in this case?
> Does this mean that compiler can pass the value either as constant ('I') or
> via register ('r')?
Right. If the same compile-time const is used multiple times, say SR of same value
to a reg, if can decide to hoist the value in a register, if you provide it "r" or
"Ir", leading to shorter overall code.
-Vineet
WARNING: multiple messages have this Message-ID (diff)
From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
To: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>,
"linux-snps-arc@lists.infradead.org"
<linux-snps-arc@lists.infradead.org>
Cc: Alexey Brodkin <Alexey.Brodkin@synopsys.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/5] ARC: add support for DSP-enabled userspace applications
Date: Wed, 4 Mar 2020 17:58:04 +0000 [thread overview]
Message-ID: <8f5af6bd-af31-8f2f-9565-f1f505e6ba11@synopsys.com> (raw)
In-Reply-To: <BY5PR12MB4034D0D8EDD029E90642012EDEE50@BY5PR12MB4034.namprd12.prod.outlook.com>
On 3/4/20 3:51 AM, Eugeniy Paltsev wrote:
>>> + "r" (_saveto), \
>>> + "r" (_readfrom), \
>>> + "I" (_aux), \
>>> + "I" (_offt) \
>>> + : \
>>
>> AEX with "I" constraint will likely be an 8 byte instructions always. Best to give
>> compiler wiggle room with "Ir"
>
> Could you please explain how "Ir" will work in this case?
> Does this mean that compiler can pass the value either as constant ('I') or
> via register ('r')?
Right. If the same compile-time const is used multiple times, say SR of same value
to a reg, if can decide to hoist the value in a register, if you provide it "r" or
"Ir", leading to shorter overall code.
-Vineet
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next prev parent reply other threads:[~2020-03-04 17:58 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-27 18:03 [RFC 0/5] ARC: handle DSP presence in HW Eugeniy Paltsev
2019-12-27 18:03 ` Eugeniy Paltsev
2019-12-27 18:03 ` [PATCH 1/5] ARC: pt_regs: remove hardcoded registers offset Eugeniy Paltsev
2019-12-27 18:03 ` Eugeniy Paltsev
2019-12-28 21:06 ` Vineet Gupta
2019-12-28 21:06 ` Vineet Gupta
2019-12-27 18:03 ` [PATCH 2/5] ARC: add helpers to sanitize config options Eugeniy Paltsev
2019-12-27 18:03 ` Eugeniy Paltsev
2020-01-06 22:47 ` Vineet Gupta
2020-01-06 22:47 ` Vineet Gupta
2019-12-27 18:03 ` [PATCH 3/5] ARC: handle DSP presence in HW Eugeniy Paltsev
2019-12-27 18:03 ` Eugeniy Paltsev
2020-01-07 1:03 ` Vineet Gupta
2020-01-07 1:03 ` Vineet Gupta
2020-01-07 1:30 ` Vineet Gupta
2020-01-07 1:30 ` Vineet Gupta
2020-01-10 14:54 ` Eugeniy Paltsev
2020-01-10 14:54 ` Eugeniy Paltsev
2020-01-13 16:49 ` Vineet Gupta
2020-01-13 16:49 ` Vineet Gupta
2019-12-27 18:03 ` [PATCH 4/5] ARC: add support for DSP-enabled userspace applications Eugeniy Paltsev
2019-12-27 18:03 ` Eugeniy Paltsev
2020-01-07 18:25 ` Vineet Gupta
2020-01-07 18:25 ` Vineet Gupta
2020-01-09 19:01 ` Eugeniy Paltsev
2020-01-09 19:01 ` Eugeniy Paltsev
2020-01-09 22:46 ` Vineet Gupta
2020-01-09 22:46 ` Vineet Gupta
2020-03-04 11:51 ` Eugeniy Paltsev
2020-03-04 11:51 ` Eugeniy Paltsev
2020-03-04 17:58 ` Vineet Gupta [this message]
2020-03-04 17:58 ` Vineet Gupta
2019-12-27 18:03 ` [PATCH 5/5] ARC: allow userspace DSP applications to use AGU extensions Eugeniy Paltsev
2019-12-27 18:03 ` Eugeniy Paltsev
2020-01-07 18:30 ` Vineet Gupta
2020-01-07 18:30 ` Vineet Gupta
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