linux-kernel - Re: [PATCH] scsi: FlashPoint: Replace arithmetic addition by bitwise OR

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Date:   Tue, 7 Feb 2023 23:18:04 +0530
From:   Deepak R Varma <drv@...lo.com>
To:     Khalid Aziz <khalid@...ehiking.org>
Cc:     jejb@...ux.ibm.com,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Saurabh Singh Sengar <ssengar@...rosoft.com>,
        Praveen Kumar <kumarpraveen@...ux.microsoft.com>
Subject: Re: [PATCH] scsi: FlashPoint: Replace arithmetic addition by bitwise
 OR

On Tue, Feb 07, 2023 at 08:28:22AM -0700, Khalid Aziz wrote:
> On 2/7/23 05:26, James Bottomley wrote:
> > On Tue, 2023-02-07 at 16:51 +0530, Deepak R Varma wrote:
> > > When adding two bit-field mask values, an OR operation offers higher
> > > performance over an arithmetic operation. So, convert such additions
> > > to an OR based expressions. Issue identified using orplus.cocci
> > > semantic patch script.
> > 
> > No it doesn't, at least not for constants, which is the entirety of
> > this patch: the compiler can find the value at compile time, so the
> > whole lot becomes a load immediate of a single value.  Whether the
> > compiler sees OR or + is immaterial to the compile time computation.
> > Perhaps Coccinelle should be fixed not to complain about this case?
> > 
> > James
> > 
> 
> Agreed. This would be lot of code changes for no benefit.

Hi Khalid,
I understand. Please disregard/drop the patch proposal.

Regards,
deepak.

> 
> --
> Khalid