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From: James Hogan <james.hogan@mips.com>
To: "Maciej W. Rozycki " <macro@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>, <linux-mips@linux-mips.org>
Subject: Re: [PATCH] MIPS: Use SLL by 0 for 32-bit truncation in `__read_64bit_c0_split'
Date: Wed, 8 Nov 2017 22:06:44 +0000	[thread overview]
Message-ID: <20171108220643.GP15260@jhogan-linux> (raw)
In-Reply-To: <alpine.DEB.2.00.1709291502060.12020@tp.orcam.me.uk>

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On Fri, Sep 29, 2017 at 04:26:31PM +0100, Maciej W. Rozycki wrote:
> Optimize `__read_64bit_c0_split' and reduce the instruction count by 1, 
> observing that a DSLL/DSRA pair by 32, is equivalent to SLL by 0, which 
> architecturally truncates the value requested to 32 bits on 64-bit MIPS 
> hardware regardless of whether the input operand is or is not a properly 
> sign-extended 32-bit value.
> 
> Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
> ---
>  Tested by compilation only to verify syntax correctnes as I do not know 
> if this execution path is actually used by any configuration (suggestions 
> welcome).  I believe it to be technically correct though, being 
> sufficiently straightforward to verify by proofreading, and an obvious 
> improvement.
> 
>  Therefore, please apply.

Thanks, Applied for 4.15.

Cheers
James

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WARNING: multiple messages have this Message-ID (diff)
From: James Hogan <james.hogan@mips.com>
To: "Maciej W. Rozycki " <macro@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org
Subject: Re: [PATCH] MIPS: Use SLL by 0 for 32-bit truncation in `__read_64bit_c0_split'
Date: Wed, 8 Nov 2017 22:06:44 +0000	[thread overview]
Message-ID: <20171108220643.GP15260@jhogan-linux> (raw)
Message-ID: <20171108220644.A2EgqAu7GP6L-0pUkBr86UjqXrq4XEt7J0I9agnunlI@z> (raw)
In-Reply-To: <alpine.DEB.2.00.1709291502060.12020@tp.orcam.me.uk>

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On Fri, Sep 29, 2017 at 04:26:31PM +0100, Maciej W. Rozycki wrote:
> Optimize `__read_64bit_c0_split' and reduce the instruction count by 1, 
> observing that a DSLL/DSRA pair by 32, is equivalent to SLL by 0, which 
> architecturally truncates the value requested to 32 bits on 64-bit MIPS 
> hardware regardless of whether the input operand is or is not a properly 
> sign-extended 32-bit value.
> 
> Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
> ---
>  Tested by compilation only to verify syntax correctnes as I do not know 
> if this execution path is actually used by any configuration (suggestions 
> welcome).  I believe it to be technically correct though, being 
> sufficiently straightforward to verify by proofreading, and an obvious 
> improvement.
> 
>  Therefore, please apply.

Thanks, Applied for 4.15.

Cheers
James

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  parent reply	other threads:[~2017-11-08 22:09 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-29 15:26 [PATCH] MIPS: Use SLL by 0 for 32-bit truncation in `__read_64bit_c0_split' Maciej W. Rozycki
2017-09-29 15:26 ` Maciej W. Rozycki
2017-09-29 19:59 ` James Hogan
2017-09-29 19:59   ` James Hogan
2017-09-29 22:39   ` Maciej W. Rozycki
2017-09-29 22:39     ` Maciej W. Rozycki
2017-11-08 22:06 ` James Hogan [this message]
2017-11-08 22:06   ` James Hogan

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